Geothermal energy from the Pannonian Basins System: An outcrop analogue study of exploration target horizons in Hungary

NASA Astrophysics Data System (ADS)

Götz, Annette E.; Sass, Ingo; Török, Ákos

2015-04-01

The characterization of geothermal reservoirs of deep sedimentary basins is supported by outcrop analogue studies since reservoir characteristics are strongly related to the sedimentary facies and thus influence the basic direction of geothermal field development and applied technology (Sass & Götz, 2012). Petro- and thermophysical rock properties are key parameters in geothermal reservoir characterization and the data gained from outcrop samples serve to understand the reservoir system. New data from the Meso- and Cenozoic sedimentary rocks of Budapest include carbonates and siliciclastics of Triassic, Eocene, Oligocene and Miocene age, exposed on the western side of the river Danube in the Buda Hills (Götz et al., 2014). Field and laboratory analyses revealed distinct horizons of different geothermal potential and thus, enable to identify and interpret corresponding exploration target horizons in geothermal prone depths in the Budapest region as well as in the Hungarian sub-basins of the Pannonian Basins System (Zala and Danube basins, Great Plain) exhibiting geothermal anomalies. References Götz, A.E., Török, Á., Sass, I., 2014. Geothermal reservoir characteristics of Meso- and Cenozoic sedimentary rocks of Budapest (Hungary). German Journal of Geosciences, 165, 487-493. Sass, I., Götz, A.E., 2012. Geothermal reservoir characterization: a thermofacies concept. Terra Nova, 24, 142-147.

Paleogeographic evolution of foldbelts adjacent to petroleum basins of Venezuela and Trinidad

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodman, E.D.; Koch, P.S.; Summa, L.L.

1996-08-01

The foldbelts of Venezuela and Trinidad have shaped the history of adjacent sedimentary basins. A set of paleogeographic maps on reconstructed bases depict the role of foldbelts in the development of the sedimentary basins of Venezuela. Some of the foldbelts are inverted, pre-Tertiary graben/passive margin systems. Other foldbelts are allochthonous nappes or parautochthons that override the Mesozoic passive margin hinge without inversion. The emergence of these foldbelts changed the course of existing river systems and provided a new source for sediments and maturation in adjacent deeps. The Merida Andes area was remobilized beginning in the Early Miocene as a zonemore » of lateral shear, along which the Bonaire Block has moved over 200 km to the northeast, dismembering the Maracaibo and Barinas basins. Late Miocene to Recent transpression and fault reactivation have driven rapid Andean uplift with thrust-related subsidence and maturation (e.g., SE Maracaibo foredeep). To the east, uplift and erosion of the Serrania del Interior (1) curtailed mid-Tertiary fluvial systems flowing northward from the igneous and sedimentary rocks of the Guyana Shield, deflecting them eastward, and (2) removed the thick early Miocene foredeep fill into a younger foredeep. Thus, the fold-thrust belts and sedimentary basins in this region are linked in their evolutionary histories.« less

Source-rock evaluation of outcrop samples from Vanuatu (Malakula, Espiritu Santo, Maewo, and Pentecost)

USGS Publications Warehouse

Buchbinder, Binyamin; Halley, Robert B.

1988-01-01

The samples collected for the present study represent only a portion of the sedimentary column in the various sedimentary basins of Vanuatu.  The characterize only the outer margins of the sedimentary basins and do not necessarily reflect the source-rock potential of the deeper (offshore) parts of the basins.

Petroleum geology of the Southern Bida Basin, Nigeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braide, S.P.

1990-05-01

The Southern Bida basin is located in central Nigeria and is a major sedimentary area with a 3.5-km-thick sedimentary fill. However, it is the least understood of Nigeria's sedimentary basins because serious oil and gas exploration has not been undertaken in the basin. The surrounding Precambrian basement rocks experienced severe deformation during the Late Panafrican phase (600 {plus minus} 150 m.y.), and developed megashears that were reactivated during the Late Campanian-Maestrichtian. The ensuing wrenchfault tectonics formed the basin. The sedimentary fill, which comprises the Lokoja Formation are chiefly, if not wholly, nonmarine clastics. These have been characterized into facies thatmore » rapidly change from basin margin to basin axis, and have undergone only relatively mild tectonic distortion. Subsurface relations of the Lokoja Formation are postulated from outcrop study. The potential source rocks are most likely within the basinal axis fill and have not been deeply buried based on vitrinite reflectance of <0.65%. These findings, with the largely nonmarine depositional environment, suggest gas and condensate are the most likely hydrocarbons. Alluvial fans and deltaic facies that interfinger with lacustrine facies provide excellent reservoir capabilities. Potential traps for hydrocarbon accumulation were formed by a northwest-southeast-trending Campanian-Maestrichtian wrench system with associated northeast-southwest-oriented normal faults. The traps include strata in alluvial fans, fractured uplifted basement blocks, and arched strata over uplifted blocks. However, the size of hydrocarbon accumulations could be limited to some extent by a lack of effective hydrocarbon seal, because the dominant seals in the formation are unconformities.« less

Major Perspectives of The Dfg-research Programm (schwerpunktprogramm) Dynamics of Sedimentary Systems Under Varying Stress Conditions By Example of The Central European Basin-system

NASA Astrophysics Data System (ADS)

Bayer, U.; Littke, R.; Gajewski, D.; Brink, H.-J.

In 2001 a major research program "Dynamics of Sedimentary Systems under Varying Stress Conditions" has been established by the German Science Foundation (DFG). The programme effectively will start early in 2002 and in some sense provides a continuation of the EUROPROBE project TESZ. However, it will focus mainly on post-Paleozoic processes. The following sub-themes for this programme capture a wide range of areas of interest, calling for interdisciplinary research: 1. Structure and evolution of the crust. This topic will be based on the three- dimensional structural interpretation, pre-stack migration, and modelling of geophysi- cal data such as seismic, gravimetric, magnetic, and magnetotelluric data. The deriva- tion of interval velocities and the prediction of lateral inhomogeneities will be essential for the interpretation of rheological properties on one hand and historical geodynamic processes on the other. 2. Basin dynamics in space and time. Methods of basin anal- ysis, seismic stratigraphy,sedimentology, sequence- and event stratigraphy should be used in combination with subsidence analysis and basin modelling to interpret facies distributions within the evolving accomodation space of a sedimentary basin. An ad- vanced interpretation of seismic lines using new modelling tools is of key interest to extract facies patterns and related petrophysical properties for the three dimensional space of a sedimentary basin. 3. Fluid- and salt dynamics. Salt dynamics is related to the recent and historic stress fields of a basin and greatly governs the sedimentation and erosion processes at the surface. In addition, the rheology of the upper crust and the temperature field within sedimentary basins greatly depends on salt doming. Fluid dynamics is coupled to the temperature and pressure field, but depends also on the permeability of sedimentary rocks which varies by more than 15 orders of magnitude. The origin of non-hydrocarbon gases (CO2, N2, H2S), each dominating over methane in specific provinces of the Central European Basin as well as in many other basins 1 worldwide, is of special interest. 4. Recent state and young processes. It is the inten- tion to develop an understanding of the most recent structural and sedimentological evolution as a response to processes intrinsic to the basin or related to external causes, including glaciation periods in the Quaternary. In particular, knowledge about recently active fault systems and salt doming will be of crucial importance for any future risk assessment, e.g. with respect to the protection of coast lines and landscapes. All above mentioned topics will benefit from the further development of modelling tools for non-linear transport processes, including compaction, porosity- and perme- ability evolution, temperature evolution, maturation of organic matter and clay miner- als, diagenesis, and fluid flow. 2

Research into Surface Wave Phenomena in Sedimentary Basins.

DTIC Science & Technology

1981-12-31

150 km of the southerly extension of the Overthrust Belt, 350 km of the Green River Basin paralleling the Uinta Mountains and 150 km across the Front...WEIDLINGER ASSOCIATES O300 SAND HiLL ROAD BUILDING 4, SUITE 245 MENLO PARK, CALIFORNIA 9462 RESEARCH INTO SURFACE WAVE PHENOMENA IN SEDIMENTARY BASINS BY...PARK, CALIFORNIA 94025 ! I RESEARCH INTO SURFACE WAVE PHENOMENA IN SEDIMENTARY BASINS I Dy G.L. Wojcik J. Isenberg F. Ma E. Richardson Prepared for

SILLi 1.0: a 1-D numerical tool quantifying the thermal effects of sill intrusions

NASA Astrophysics Data System (ADS)

Iyer, Karthik; Svensen, Henrik; Schmid, Daniel W.

2018-01-01

Igneous intrusions in sedimentary basins may have a profound effect on the thermal structure and physical properties of the hosting sedimentary rocks. These include mechanical effects such as deformation and uplift of sedimentary layers, generation of overpressure, mineral reactions and porosity evolution, and fracturing and vent formation following devolatilization reactions and the generation of CO2 and CH4. The gas generation and subsequent migration and venting may have contributed to several of the past climatic changes such as the end-Permian event and the Paleocene-Eocene Thermal Maximum. Additionally, the generation and expulsion of hydrocarbons and cracking of pre-existing oil reservoirs around a hot magmatic intrusion are of significant interest to the energy industry. In this paper, we present a user-friendly 1-D finite element method (FEM)-based tool, SILLi, which calculates the thermal effects of sill intrusions on the enclosing sedimentary stratigraphy. The model is accompanied by three case studies of sills emplaced in two different sedimentary basins, the Karoo Basin in South Africa and the Vøring Basin off the shore of Norway. An additional example includes emplacement of a dyke in a cooling pluton which forgoes sedimentation within a basin. Input data for the model are the present-day well log or sedimentary column with an Excel input file and include rock parameters such as thermal conductivity, total organic carbon (TOC) content, porosity and latent heats. The model accounts for sedimentation and burial based on a rate calculated by the sedimentary layer thickness and age. Erosion of the sedimentary column is also included to account for realistic basin evolution. Multiple sills can be emplaced within the system with varying ages. The emplacement of a sill occurs instantaneously. The model can be applied to volcanic sedimentary basins occurring globally. The model output includes the thermal evolution of the sedimentary column through time and the changes that take place following sill emplacement such as TOC changes, thermal maturity and the amount of organic and carbonate-derived CO2. The TOC and vitrinite results can be readily benchmarked within the tool to present-day values measured within the sedimentary column. This allows the user to determine the conditions required to obtain results that match observables and leads to a better understanding of metamorphic processes in sedimentary basins.

Extensional Tectonics and Sedimentary Architecture Using 3-D Seismic Data: An Example from Hydrocarbon-Bearing Mumbai Offshore Basin, West Coast of India

NASA Astrophysics Data System (ADS)

Mukhopadhyay, D. K.; Bhowmick, P. K.; Mishra, P.

2016-12-01

In offshore sedimentary basins, analysis of 3-D seismic data tied with well log data can be used to deduce robust isopach and structure contour maps of different stratigraphic formations. The isopach maps give depocenters whereas structure contour maps give structural relief at a specific time. Combination of these two types of data helps us decipher horst-graben structures, sedimentary basin architecture and tectono-stratigraphic relations through Tertiary time. Restoration of structural cross sections with back-stripping of successively older stratigraphic layers leads to better understand tectono-sedimentary evolution of a basin. The Mumbai (or Bombay) Offshore Basin is the largest basin off the west coast of India and includes Bombay High giant oil/gas field. Although this field was discovered in 1974 and still producing, the basin architecture vis-à-vis structural evolution are not well documented. We take the approach briefly outlined above to study in detail three large hydrocarbon-bearing structures located within the offshore basin. The Cretaceous Deccan basalt forms the basement and hosts prodigal thickness (> 8 km at some localities) of Tertiary sedimentary formations.A two stage deformation is envisaged. At the first stage horst and graben structures formed due to approximately E-W extensional tectonics. This is most spectacularly seen at the basement top level. The faults associated with this extension strike NNW. At the second stage of deformation a set of ENE-striking cross faults have developed leading to the formation of transpressional structures at places. High rate of early sedimentation obliterated horst-graben architecture to large extent. An interesting aspect emerges is that the all the large-scale structures have rather low structural relief. However, the areal extent of such structures are very large. Consequently, these structures hold commercial quantities of oil/gas.

Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

PubMed

Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

2015-01-01

A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front" character.

Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China

PubMed Central

Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

2015-01-01

A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a “small plain, big front” character. PMID:26075611

Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

NASA Astrophysics Data System (ADS)

Baker, P. A.; Fritz, S. C.; Silva, C. G.; Rigsby, C. A.; Absy, M. L.; Almeida, R. P.; Caputo, M.; Chiessi, C. M.; Cruz, F. W.; Dick, C. W.; Feakins, S. J.; Figueiredo, J.; Freeman, K. H.; Hoorn, C.; Jaramillo, C.; Kern, A. K.; Latrubesse, E. M.; Ledru, M. P.; Marzoli, A.; Myrbo, A.; Noren, A.; Piller, W. E.; Ramos, M. I. F.; Ribas, C. C.; Trnadade, R.; West, A. J.; Wahnfried, I.; Willard, D. A.

2015-12-01

This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

USGS Publications Warehouse

Baker, P.A.; Fritz, S.C.; Silva, C.G.; Rigsby, C.A.; Absy, M.L.; Almeida, R.P.; Caputo, Maria C.; Chiessi, C.M.; Cruz, F.W.; Dick, C.W.; Feakins, S.J.; Figueiredo, J.; Freeman, K.H.; Hoorn, C.; Jaramillo, C.A.; Kern, A.; Latrubesse, E.M.; Ledru, M.P.; Marzoli, A.; Myrbo, A.; Noren, A.; Piller, W.E.; Ramos, M.I.F.; Ribas, C.C.; Trinadade, R.; West, A.J.; Wahnfried, I.; Willard, Debra A.

2015-01-01

This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

Structural framework and hydrocarbon potential of Ross Sea, Antarctica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, A.K.; Davey, F.J.

The 400 to 1100-m deep continental shelf of the Ross Sea is underlain by three major sedimentary basins (Eastern basin, Central trough, and Victoria Land basin), which contain 5 to 6 km of sedimentary rock of Late Cretaceous(.) and younger age. An addition 6 to 7 km of older sedimentary and volcanic rocks lie within the Victoria Land basin. Eroded basement ridges of early Paleozoic(.) and older rocks similar to those of onshore Victoria Land separate the basins. The three basins formed initially in late Mesozoic time during an early period of rifting between East and West Antarctica. The Easternmore » basin is a 300-km wide, asymmetric basement trough that structurally opens into the Southern Ocean. A seaward-prograding sequence of late Oligocene and younger glacial deposits covers a deeper, layered sequence of Paleogene(.) and older age. The Central trough, a 100-km wide depression, is bounded by basement block faults and is filled with a nearly flat-lying sedimentary section. A prominent positive gravity anomaly, possibly caused by rift-related basement rocks, lies along the axis of the basin. The Victoria Land basin, unlike the other two basins, additionally contains a Paleogene(.) to Holocene rift zone, the Terror Rift. Rocks in the rift, near the axis of the 150-km wide basement half-graben, show extensive shallow faulting and magmatic intrusion of the sedimentary section. The active Terror rift and older basin structures extend at least 300 km along the base of the Transantarctic Mountains. Petroleum hydrocarbons have not been reported in the Ross Sea region, with possible exception of ethane gas found in Deep Sea Drilling Project cores from the Eastern basin. Model studies indicate that hydrocarbons could be generated at depths of 3.5 to 6 km within the sedimentary section. The best structures for hydrocarbon entrapment occur in the Victoria Land basin and associated Terror Rift.« less

Submarine landslides in Arctic sedimentation: Canada Basin

USGS Publications Warehouse

Mosher, David C.; Shimeld, John; Hutchinson, Deborah R.; Lebedova-Ivanova, N; Chapman, C.

2016-01-01

Canada Basin of the Arctic Ocean is the least studied ocean basin in the World. Marine seismic field programs were conducted over the past 6 years using Canadian and American icebreakers. These expeditions acquired more than 14,000 line-km of multibeam bathymetric and multi-channel seismic reflection data over abyssal plain, continental rise and slope regions of Canada Basin; areas where little or no seismic reflection data existed previously. Canada Basin is a turbidite-filled basin with flat-lying reflections correlateable over 100s of km. For the upper half of the sedimentary succession, evidence of sedimentary processes other than turbidity current deposition is rare. The Canadian Archipelago and Beaufort Sea margins host stacked mass transport deposits from which many of these turbidites appear to derive. The stratigraphic succession of the MacKenzie River fan is dominated by mass transport deposits; one such complex is in excess of 132,000 km2 in area and underlies much of the southern abyssal plain. The modern seafloor is also scarred with escarpments and mass failure deposits; evidence that submarine landsliding is an ongoing process. In its latest phase of development, Canada Basin is geomorphologically confined with stable oceanographic structure, resulting in restricted depositional/reworking processes. The sedimentary record, therefore, underscores the significance of mass-transport processes in providing sediments to oceanic abyssal plains as few other basins are able to do.

Hydrogeologic map of the Islamic Republic of Mauritania (phase V, deliverable 56), Synthesis of hydrologic data (phase V, deliverable 57), and chemical hydrologic map of the Islamic Republic of Mauritania (added value): Chapter C in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

USGS Publications Warehouse

Friedel, Michael J.; Finn, Carol A.; Horton, John D.

2015-01-01

A hydrogeologic study was conducted to support mineral-resource assessment activities in Mauritania, Africa. Airborne magnetic depth estimates reveal two primary groundwater basins: the porous coastal Continental Terminal Basin (fill deposits); and the interior, fractured interior Taoudeni Basin. In the Continental Terminal Basin, there is uniform vertical recharge and localized discharge that is coincident with groundwater pumping at Nouakchott. This pumping center induces eastward flow of groundwater from the Atlantic Ocean resulting in a salinity gradient that diminishes quality over 100 km. Groundwater also flows southward into the basin from Western Sahara. By contrast, an interbasin exchange occurs as fresh groundwater flows westward from the Taoudeni Basin. In the Taoudeni Basin, zones of local recharge occur in three areas: northwest at the edge of the Rgueïbat Shield; at the city of Tidjikja; and near the center of the basin. Groundwater also flows across international boundaries: northward into Western Sahara and westward into Mali. At the southern country boundary, the Senegal River serves as both a source and sink of fresh groundwater to the Continental Terminal and Taoudeni basins. Using a geographical information system, thirteen hydrogeologic units are identified based on lateral extent and distinct hydraulic properties for future groundwater model development. Combining this information with drilling productivity, groundwaterquality, and geophysical interpretations (fracturing and absence of subsurface dikes) three potential water-resource development targets were identified: sedimentary rocks of the Jurassic, Cretaceous, and Quaternary Periods; sedimentary rocks of Cambrian and Ordovician Periods; and sedimentary rocks of Neoproterozoic age.

Rapid extension in an Eocene volcanic arc: Structure and paleogeography of an intra-arc half graben in central Idaho

USGS Publications Warehouse

Janecke, S.U.; Hammond, B.F.; Snee, L.W.; Geissman, J.W.

1997-01-01

A study of extension, volcanism, and sedimentation in the middle Eocene Panther Creek half graben in central Idaho shows that it formed rapidly during an episode of voluminous volcanism. The east-southeast-tilted Panther Creek half graben developed across the northeast edge of the largest cauldron complex of the Challis volcanic field and along the northeast-trending Trans-Challis fault zone. Two normal fault systems bound the east side of the half graben. One fault system strikes northeast, parallel to the Trans-Challis fault zone, and the other strikes north to northwest. The geometry of the basin-fill deposits shows that movement on these two normal fault systems was synchronous and that both faults controlled the development of the Panther Creek half graben. Strikes of the synextension volcanic and sedimentary rocks are similar throughout the half graben, whereas dips decrease incrementally upsection from as much as 60?? to less than 10??. Previous K-Ar dates and a new 40Ar/39Ar plateau date from the youngest widespread tuff in the basin suggest that most of basin formation spanned 3 m.y. between about 47.7 Ma and 44.5 Ma. As much as 6.5 km of volcanic and sedimentary rocks were deposited during that time. Although rates of extension and subsidence were very high, intense volcanic activity continually filled the basin with ash-flow tuffs, outpacing subsidence and sedimentation, until the end of basin development. After the abrupt end of Challis volcanism, locally derived pebble to boulder conglomerate and massive, reworked ash accumulated in the half graben. These sedimentary rocks make up a small part of the basin fill in the Panther Creek half graben and were derived mainly from Proterozoic metasedimentary rocks uplifted in the footwall of the basin. The east-southeast tilt of the sedimentary rocks, their provenance and coarse grain size, and the presence of a gravity slide block derived from tilted volcanic rocks in the hanging wall attest to continued tectonism during conglomerate deposition. Provenance data from the sedimentary rocks imply that the highland in the footwall of the Panther Creek half graben was never thickly blanketed by synex-tension volcanic rocks, despite intense volcanic activity. Analysis of the Panther Creek half graben and other intra-arc rift basins supports previous interpretations that relative rates of volcanism and subsidence control the proportion of volcanic rocks deposited in intra-arc rifts.

Report of the Workshop on Geologic Applications of Remote Sensing to the Study of Sedimentary Basins

NASA Technical Reports Server (NTRS)

Lang, H. R. (Editor)

1985-01-01

The Workshop on Geologic Applications of Remote Sensing to the Study of Sedimentary Basins, held January 10 to 11, 1985 in Lakewood, Colorado, involved 43 geologists from industry, government, and academia. Disciplines represented ranged from vertebrate paleontology to geophysical modeling of continents. Deliberations focused on geologic problems related to the formation, stratigraphy, structure, and evolution of foreland basins in general, and to the Wind River/Bighorn Basin area of Wyoming in particular. Geological problems in the Wind River/Bighorn basin area that should be studied using state-of-the-art remote sensing methods were identified. These include: (1) establishing the stratigraphic sequence and mapping, correlating, and analyzing lithofacies of basin-filling strata in order to refine the chronology of basin sedimentation, and (2) mapping volcanic units, fracture patterns in basement rocks, and Tertiary-Holocene landforms in searches for surface manifestations of concealed structures in order to refine models of basin tectonics. Conventional geologic, topographic, geophysical, and borehole data should be utilized in these studies. Remote sensing methods developed in the Wind River/Bighorn Basin area should be applied in other basins.

The Devonian Marcellus Shale and Millboro Shale

USGS Publications Warehouse

Soeder, Daniel J.; Enomoto, Catherine B.; Chermak, John A.

2014-01-01

The recent development of unconventional oil and natural gas resources in the United States builds upon many decades of research, which included resource assessment and the development of well completion and extraction technology. The Eastern Gas Shales Project, funded by the U.S. Department of Energy in the 1980s, investigated the gas potential of organic-rich, Devonian black shales in the Appalachian, Michigan, and Illinois basins. One of these eastern shales is the Middle Devonian Marcellus Shale, which has been extensively developed for natural gas and natural gas liquids since 2007. The Marcellus is one of the basal units in a thick Devonian shale sedimentary sequence in the Appalachian basin. The Marcellus rests on the Onondaga Limestone throughout most of the basin, or on the time-equivalent Needmore Shale in the southeastern parts of the basin. Another basal unit, the Huntersville Chert, underlies the Marcellus in the southern part of the basin. The Devonian section is compressed to the south, and the Marcellus Shale, along with several overlying units, grades into the age-equivalent Millboro Shale in Virginia. The Marcellus-Millboro interval is far from a uniform slab of black rock. This field trip will examine a number of natural and engineered exposures in the vicinity of the West Virginia–Virginia state line, where participants will have the opportunity to view a variety of sedimentary facies within the shale itself, sedimentary structures, tectonic structures, fossils, overlying and underlying formations, volcaniclastic ash beds, and to view a basaltic intrusion.

Application of MSS/LANDSAT images to the structural study of recent sedimentary areas: Campos Sedimentary Basin, Rio de Janeiro, Brazil

NASA Technical Reports Server (NTRS)

Parada, N. D. J. (Principal Investigator); Barbosa, M. P.

1983-01-01

Visual and computer aided interpretation of MSS/LANDSAT data identified linear and circular features which represent the ""reflexes'' of the crystalline basement structures in the Cenozoic sediments of the emergent part of the Campos Sedimentary Basin.

A reassessment of the Archean-Mesoproterozoic tectonic development of the southeastern Chhattisgarh Basin, Central India through detailed aeromagnetic analysis

NASA Astrophysics Data System (ADS)

Sridhar, M.; Ramesh Babu, V.; Markandeyulu, A.; Raju, B. V. S. N.; Chaturvedi, A. K.; Roy, M. K.

2017-08-01

We constrained the geological framework over polydeformed Paleoproterozoic Sonakhan Greenstone Belt and addressed the tectonic evolution of Singhora basin in the fringes of Bastar Craton, central India by utilizing aeromagnetic data interpretation, 2.5D forward modelling and 3D magnetic susceptibility inversions. The Sonakhan Greenstone Belt exposes volcano-sedimentary sequences of the Sonakhan Group within NNW-SSE to NW-SE trending linear belts surrounded by granite gneisses, which are unconformably overlain by sedimentary rocks of Chhattisgarh Basin. The orientations of aeromagnetic anomalies are coincident with geological trends and appear to correlate with lithology and geologic structure. Regional magnetic anomalies and lineaments reveal both NNW-SSE and NE-SW trends. Prominent E-W trending linear, high amplitude magnetic anomalies are interpreted as the Trans-Chhattisgarh Aeromagnetic Lineament (TCAL). NW-SE trending aeromagnetic signatures related to Sonakhan Greenstone Belt extends below the Singhora sedimentary rocks and forms the basement in the west. The analysis suggests that TCAL is a block fault with northern block down-thrown and affected the basement rocks comprising the Sonakhan Greenstone Belt and Samblapur Granitoids. The episode of faulting represented by the TCAL is pre-Singhora sedimentation and played a vital role in basin evolution. The basement configuration image generated by estimates of depth to magnetic basement suggests a complex pattern of NNE-SSW to NE-SW trending depressions separated by a linear N-S trending basement ridge. It is inferred from the 3D magnetic susceptibility inversion that the thickness of sediments is more towards the eastern basin margin and the N-S ridge is a manifestation of post sedimentary faulting. Results of 2.5D modelling of a WNW-ESE profile across the Singhora Basin combined with results from 3D inversion suggest suggests the basin subsidence was controlled by NE-SW trending regional faults in an active system. The basin geometry evolved by E-W block faulting overprinted by NE-SW trending pre- to syn-depositional normal faults generating NE-SW depression, which are affected by N-S trend post-sedimentary faulting. Though the present work relates the basin evolution with the initiation of rift basin, it warrants further work to establish the deformation within the basin pertaining to the proximal thrust and uplift along the craton fringe.

Evidence of synsedimentary microbial activity and iron deposition in ferruginous crusts of the Late Cenomanian Utrillas Formation (Iberian Basin, central Spain)

NASA Astrophysics Data System (ADS)

García-Hidalgo, José F.; Elorza, Javier; Gil-Gil, Javier; Herrero, José M.; Segura, Manuel

2018-02-01

Ferruginous sandstones and crusts are prominent sedimentary features throughout the continental (braided)-coastal siliciclastic (estuarine-tidal) wedges of the Late Cenomanian Utrillas Formation in the Iberian Basin. Crust types recognized are: Ferruginous sandy crusts (Fsc) with oxides-oxyhydroxides (hematite and goethite) concentrated on sandstone tops presenting a fibro-radial internal structure reminding organic structures that penetrate different mineral phases, suggesting the existence of bacterial activity in crust development; Ferruginous muddy crusts (Fmc) consisting of wavy, laminated, microbial mats, being composed mainly of hematite. On the other hand, a more dispersed and broader mineralization included as Ferruginous sandstones with iron oxides and oxyhydroxides (hematite and goethite) representing a limited cement phase on these sediments. The presence of microbial remains, ferruginous minerals, Microbially-induced sedimentary structures, microbial laminites and vertebrate tracks preserved due to the presence of biofilms suggest firstly a direct evidence of syn-depositional microbial activity in these sediments; and, secondly, that iron accumulation and ferruginous crusts development occurred immediately after deposition of the host, still soft sediments. Ferruginous crusts cap sedimentary cycles and they represent the gradual development of hard substrate conditions, and the development of a discontinuity surface at the top of the parasequence sets, related to very low sedimentary rates; the overlying sediments record subsequent flooding of underlying shallower environments; crusts are, consequently, interpreted as boundaries for these higher-order cycles in the Iberian Basin.

Sedimentary exhalative (sedex) zinc-lead-silver deposit model

USGS Publications Warehouse

Emsbo, Poul; Seal, Robert R.; Breit, George N.; Diehl, Sharon F.; Shah, Anjana K.

2016-10-28

This report draws on previous syntheses and basic research studies of sedimentary exhalative (sedex) deposits to arrive at the defining criteria, both descriptive and genetic, for sedex-type deposits. Studies of the tectonic, sedimentary, and fluid evolution of modern and ancient sedimentary basins have also been used to select defining criteria. The focus here is on the geologic characteristics of sedex deposit-hosting basins that contain greater than 10 million metric tons of zinc and lead. The enormous size of sedex deposits strongly suggests that basin-scale geologic processes are involved in their formation. It follows that mass balance constraints of basinal processes can provide a conceptual underpinning for the evaluation of potential ore-forming mechanisms and the identification of geologic indicators for ore potential in specific sedimentary basins. Empirical data and a genetic understanding of the physicochemical, geologic, and mass balance conditions required for each of these elements are used to establish a hierarchy of quantifiable geologic criteria that can be used in U.S. Geological Survey national assessments.  In addition, this report also provides a comprehensive evaluation of environmental considerations associated with the mining of sedex deposits.

Imaging the Moho beneath Sedimentary Basins: A Comparative Study of Virtual Deep Seismic Sounding (VDSS) and P Wave Receiver Functions (PRF)

NASA Astrophysics Data System (ADS)

Liu, T.; Klemperer, S. L.; Yu, C.; Ning, J.

2017-12-01

In the past decades, P wave receiver functions (PRF) have been routinely used to image the Moho, although it is well known that PRFs are susceptible to contamination from sedimentary multiples. Recently, Virtual Deep Seismic Sounding (VDSS) emerged as a novel method to image the Moho. However, despite successful applications of VDSS on multiple datasets from different areas, how sedimentary basins affect the waveforms of post-critical SsPmp, the Moho reflection phase used in VDSS, is not widely understood. Here, motivated by a dataset collected in the Ordos plateau, which shows distinct effects of sedimentary basins on SsPmp and Pms waveforms, we use synthetic seismograms to study the effects of sedimentary basins on SsPmp and Pms, the phases used in VDSS and PRF respectively. The results show that when the sedimentary thickness is on the same order of magnitude as the dominant wavelength of the incident S wave, SsPmp amplitude decreases significantly with S velocity of the sedimentary layer, whereas increasing sedimentary thickness has little effect in SsPmp amplitude. Our explanation is that the low S velocity layer at the virtual source reduces the incident angle of S wave at the free surface, thus decreases the S-to-P reflection coefficient at the virtual source. In addition, transmission loss associated with the bottom of sedimentary basins also contributes to reducing SsPmp amplitude. This explains not only our observations from the Ordos plateau, but also observations from other areas where post-critical SsPmp is expected to be observable, but instead is too weak to be identified. As for Pms, we observe that increasing sedimentary thickness and decreasing sedimentary velocities both can cause interference between sedimentary multiples and Pms, rendering the Moho depths inferred from Pms arrival times unreliable. The reason is that although Pms amplitude does not vary with sedimentary thickness or velocities, as sedimentary velocities decrease and thickness grows, the sedimentary multiples will become stronger and arrive later, and will eventually interfere with Pms. In summary, although both VDSS and PRF are subject to sedimentary effects, when the sedimentary velocity is relatively high, we can still expect VDSS to give reasonable estimations of Moho depths, whereas PRF in such cases might be too noisy to use.

Geothermal resources of California sedimentary basins

USGS Publications Warehouse

Williams, C.F.; Grubb, F.V.; Galanis, S.P.

2004-01-01

The 2004 Department of Energy (DOE) Strategic Plan for geothermal energy calls for expanding the geothermal resource base of the United States to 40,000 MW of electric power generating potential. This will require advances in technologies for exploiting unconventional geothermal resources, including Enhanced Geothermal Systems (EGS) and geopressured geothermal. An investigation of thermal conditions in California sedimentary basins through new temperature and heat flow measurements reveals significant geothermal potential in some areas. In many of the basins, the combined cooling effects of recent tectonic and sedimentary processes result in relatively low (<60 mW/m2) heat flow and geothermal gradients. For example, temperatures in the upper 3 km of San Joaquin, Sacramento and Ventura basins are typically less than 125??C and do not reach 200??c by 5 km. By contrast, in the Cuyama, Santa Maria and western Los Angeles basins, heat flow exceeds 80 mW/m2 and temperatures near or above 200??C occur at 4 to 5 km depth, which represents thermal conditions equivalent to or hotter than those encountered at the Soultz EGS geothermal site in Europe. Although the extractable geothermal energy contained in these basins is not large relative to the major California producing geothermal fields at The Geysers or Salton Sea, the collocation in the Los Angeles basin of a substantial petroleum extraction infrastructure and a major metropolitan area may make it attractive for eventual geothermal development as EGS technology matures.

The Effect of Sedimentary Basins on Through-Passing Short-Period Surface Waves

NASA Astrophysics Data System (ADS)

Feng, L.; Ritzwoller, M. H.

2017-12-01

Surface waves propagating through sedimentary basins undergo elastic wave field complications that include multiple scattering, amplification, the formation of secondary wave fronts, and subsequent wave front healing. Unless these effects are accounted for accurately, they may introduce systematic bias to estimates of source characteristics, the inference of the anelastic structure of the Earth, and ground motion predictions for hazard assessment. Most studies of the effects of basins on surface waves have centered on waves inside the basins. In contrast, we investigate wave field effects downstream from sedimentary basins, with particular emphasis on continental basins and propagation paths, elastic structural heterogeneity, and Rayleigh waves at 10 s period. Based on wave field simulations through a recent 3D crustal and upper mantle model of East Asia, we demonstrate significant Rayleigh wave amplification downstream from sedimentary basins in eastern China such that Ms measurements obtained on the simulated wave field vary by more than a magnitude unit. We show that surface wave amplification caused by basins results predominantly from elastic focusing and that amplification effects produced through 3D basin models are reproduced using 2D membrane wave simulations through an appropriately defined phase velocity map. The principal characteristics of elastic focusing in both 2D and 3D simulations include (1) retardation of the wave front inside the basins; (2) deflection of the wave propagation direction; (3) formation of a high amplitude lineation directly downstream from the basin bracketed by two low amplitude zones; and (4) formation of a secondary wave front. Finally, by comparing the impact of elastic focusing with anelastic attenuation, we argue that on-continent sedimentary basins are expected to affect surface wave amplitudes more strongly through elastic focusing than through the anelastic attenuation.

Characteristics of Holocene sediments in the Gunsan Basin, central Yellow Sea

NASA Astrophysics Data System (ADS)

Woo, H. J.; Huh, S.; Jeong, K. S.; Lee, J. H.; Ham, A.; Kang, J.

2016-12-01

The Gunsan Basin, in the eastern part of the South Yellow Sea Basin, is filled by terrestrial sedimentary rocks, maximally up to 8 km deep on the basement of metamorphic rocks that constitutes the Yangtze Platform. The uppermost sedimentary layer (generally less than 1 km) appears to have formed experiencing the repeated marine environments since the middle Miocene. This study is to investigate the characteristics of Holocene sediments in the Gunsan Basin, based on interpretation of core sediments and high-resolution shallow (Sparker and Chirp) seismic profiles. The surface sediments in the basin consist of sand (56.6% on the average), silt (18.4%), and clay (25.0%) with a mean grain size of 1.5 to 7.8 Ø. Sand is prevalent (63.8 to 98.3%) in and around the Yellow Sea Trough lying in the eastern part of the basin. The sandy sediments are regarded as relict sediments deposited in the last glacial maximum (LGM). The sedimentary environments are classified, based on the acoustic and morphological characters of high-resolution shallow (Sparker and Chirp) seismic profiles, into mud zone, deformed zone, and sand ridges with sand waves zone from the west to the east in the Gunsan Basin. The deformed zone in the central Yellow Sea is a mixing area of sediments derived from China and Korea, where there are a number of paleochannels and erosional surfaces in the direction of northwest-southeast. The deformed zone represents non-deposition or erosion in the central Yellow Sea during the Holocene. Tidal sand ridges and sand waves are well developed along the coast of Korea. Modern sand ridges are generally moving in the northeast-southwest direction, which coincide with dominant tidal current direction. Fifteen piston cores were collected in the basin to investigate the general geological characters of the marine sedimentary sequence. In comparison with three cores in the southern basin, the sand contents tend to increase in the direction of east. 14C dates from three cores near border of Exclusive Economic Zone (EEZ) of Korea reveal that Holocene sediments have accumulated at the rate 6-18 cm/ka. The mud sediments sequentially change sandy mud to mud after the sea-level rise. In the Gunsan Basin, paleochannels played an important role in sedimentary processes during low sea-level periods of Quaternary.

Thermal history determined by fission-track dating for three sedimentary basins in California and Wyoming

USGS Publications Warehouse

Naeser, Nancy D.

1984-01-01

The use of fission-tracks is demonstrated in studies of time-temperature relationships in three sedimentary basins in the western United States; in the Tejon Oil Field area of the southern San Joaquin Valley, California; in the northeastern Green River basin, Wyoming, and in drill holes in the southern Powder River Basin, Wyoming.

The problem of genesis and systematic of sedimentary units of hydrocarbon reservoirs

NASA Astrophysics Data System (ADS)

Zhilina, E. N.; Chernova, O. S.

2017-12-01

The problem of identifying and ranking sedimentation, facies associations and their constituent parts - lithogenetic types of sedimentary rocks was considered. As a basis for paleo-sedimentary modelling, the author has developed a classification for terrigenous natural reservoirs,that for the first time links separate sedimentological units into a single hierarchical system. Hierarchy ranking levels are based on a compilation of global knowledge and experience in sediment geology, sedimentological study and systematization, and data from deep-well coresrepresentingJurassichydrocarbon-bearing formationsof the southeastern margin of the Western Siberian sedimentary basin.

The Bowser and Sustut Basins, Northern British Columbia, Canada: Insights From Analysis of Magnetic Anomaly Data.

NASA Astrophysics Data System (ADS)

Baker, J.; Lowe, C.

2005-12-01

The Bowser and Sustut basins occupy an area of more than 60,000 km2 in northern British Columbia, Canada. They comprise three, dominantly sedimentary, stratigraphic successions, in part overlapping in age: the Bowser Lake Group, the Skeena Group, and the Sustut Group. These three successions overlie arc volcanic and volcaniclastic strata of Stikinia, an allochtonous island arc terrane that accreted to the western margin of North America in the Early Jurassic to early Middle Jurassic. All three basin successions and underlying Stikinia were deformed during development of a thin-skinned fold and thrust belt (the Skeena Fold and Thrust Belt) in Cretaceous and possibly into earliest Tertiary time. Recently, the basins have been the focus of intense geological studies which have resulted in major revisions to the stratigraphic and structural framework of the basins and demonstrated that they have significantly higher petroleum potential than had been previously recognized. To advance these new findings further requires better imaging of the three-dimensional geometry and architecture of the basins. In this study we harness existing magnetic anomaly data to provide the first quantitative estimates of sedimentary thickness across the entire extents of both basins. Our results, which are in general in accord with geological interpretations, indicate that basin-fill is relatively thin and fairly uniform in the Sustut Basin (2.5-3 km), but highly variable in the Bowser Basin, ranging from less than 2 km to more than 6 km. Overall, sedimentary fill is thicker in the northern half of Bowser Basin compared to the south and is typically less than 2 km near the basins northern, western and southern margins. In addition, we demonstrate how a large, buried intrusion beneath the northeast part of Bowser Basin can account for an observed magnetic anomaly and explain the high coalification gradients and localized high maturation levels of the overlying sedimentary rocks. Neither of the latter can be adequately explained by the estimated burial depths. We delineate at least one regionally extensive fault that is more than 150 km long and that cuts basement of Bowser Basin. The fault may have facilitated migration of hydrocarbons sourced in the basement into Bowser Basin. We show how magnetic data can be used to refine isotopically-determined ages of the late Tertiary Maitland Volcanics that overlap the sedimentary fill and to demonstrate that the volcanism must have been episodic and not the result of a single eruptive event. Collectively, these findings provide new insights into the crustal architecture of northern British Columbia and important constraints for geodynamic models of the basins evolution and their resource potential.

Sedimentary record of late Paleozoic to Recent tectonism in central Asia — analysis of subsurface data from the Turan and south Kazak domains

NASA Astrophysics Data System (ADS)

Thomas, J. C.; Cobbold, P. R.; Shein, V. S.; Le Douaran, S.

1999-11-01

The Turan and south Kazak domains (TSK) are in central Asia, between the Caspian Sea and the Tien Shan. The area is covered by sediments, deposited since the Late Permian during a series of tectonic events closely related to the history of two oceanic domains, Paleotethys and Neotethys. Sedimentary basins on the TSK therefore provide constraints on the tectonic development of the southern margin of Eurasia since the Late Permian. Our study is based on structure-contour maps and isopach maps of five key stratigraphic markers, of Late Permian to Tertiary age. Isopach maps help locate major faults and delimit sedimentary basins, providing information on vertical motions and, in some instances, horizontal motions. Subsidence associated with extension appears to have dominated the TSK, from the Late Permian to the Eocene. The extension may have been of back-arc type in southern Eurasia, next to the active margin, where the Paleotethys and Neotethys successively subducted toward the north. Here, sedimentary basins are both wide and deep (up to 15 km). During the Mesozoic, two compressional events of regional significance occurred in association with accretion of continental blocks at the southern margin of Eurasia. The first one, at the end of the Triassic, led to strong selective inversion of basins over the Turan domain. The second one, during the Late Jurassic-Early Cretaceous, had weaker effects. Since the Oligocene, following collision of both India and Arabia with Eurasia, inversion has become more generalized and compressional basins have formed on the TSK. Throughout the entire history of development of the TSK, from the Late Permian to the Tertiary, structures of Paleozoic and early Mesozoic age have exerted a strong control on sedimentation and especially on the location of depocenters. The south Kazak domain has registered little subsidence, in comparison with the Turan domain, where some basins have become very deep.

Stratigraphy and tectonic history of the Tucson Basin, Pima County, Arizona, based on the Exxon state (32)-1 well

USGS Publications Warehouse

Houser, Brenda B.; Peters, Lisa; Esser, Richard P.; Gettings, Mark E.

2004-01-01

The Tucson Basin is a relatively large late Cenozoic extensional basin developed in the upper plate of the Catalina detachment fault in the southern Basin and Range Province, southeastern Arizona. In 1972, Exxon Company, U.S.A., drilled an exploration well (Exxon State (32)-1) near the center of the Tucson Basin that penetrated 3,658 m (12,001 ft) of sedimentary and volcanic rocks above granitoid basement. Detailed study of cuttings and geophysical logs of the Exxon State well has led to revision of the previously reported subsurface stratigraphy for the basin and provided new insight into its depositional and tectonic history. There is evidence that detachment faulting and uplift of the adjacent Catalina core complex on the north have affected the subsurface geometry of the basin. The gravity anomaly map of the Tucson Basin indicates that the locations of subbasins along the north-trending axis of the main basin coincide with the intersection of this axis with west-southwest projections of synforms in the adjacent core complex. In other words, the subbasins overlie synforms and the ridges between subbasins overlie antiforms. The Exxon State well was drilled near the center of one of the subbasins. The Exxon well was drilled to a total depth of 3,827 m (12,556 ft), and penetrated the following stratigraphic section: Pleistocene(?) to middle(?) Miocene upper basin-fill sedimentary rocks (0-908 m [0-2,980 ft]) lower basin-fill sedimentary rocks (908-1,880 m [2,980-6,170 ft]) lower Miocene and upper Oligocene Pantano Formation (1,880-2,516 m [6,170-8,256 ft]) upper Oligocene to Paleocene(?) volcanic and sedimentary rocks (2,516-3,056 m [8,256-10,026 ft]) Lower Cretaceous to Upper Jurassic Bisbee Group (3,056-3,658 m [10,026-12,001 ft]) pre-Late Jurassic granitoid plutonic rock (3,658-3,827 m [12,001- 12,556 ft]). Stratigraphy and Tectonic History of the Tucson Basin, Pima County, Arizona, Based on the Exxon State (32)-1 Well The 1,880 m (6,170 ft) of basin-fill sedimentary rocks consist of alluvial-fan, alluvial-plain, and playa facies. The uppermost unit, a 341-m-thick (1,120-ft) lower Pleistocene and upper Pliocene alluvial-fan deposit (named the Cienega Creek fan in this study), is an important aquifer in the Tucson basin. The facies change at the base of the alluvial fan may prove to be recognizable in well data throughout much of the basin. The well data show that a sharp boundary at 908 m (2,980 ft) separates relatively unconsolidated and undeformed upper basin fill from denser, significantly faulted lower basin fill, indicating that there were two stages of basin filling in the Tucson basin as in other basins of the region. The two stages apparently occurred during times of differing tectonic style in the region. In the Tucson area the Pantano Formation, which contains an andesite flow dated at about 25 Ma, fills a syntectonic basin in the hanging wall of the Catalina detachment fault, reflecting middle Tertiary extension on the fault. The formation in the well is 636 m thick (2,086 ft) and consists of alluvial-fan, playa, and lacustrine sedimentary facies, a lava flow, and rock- avalanche deposits. Analysis of the geophysical logs indicates that a K-Ar date of 23.4 Ma reported previously for the Pantano interval of the well was obtained on selected cuttings collected from a rock-avalanche deposit near the base of the unit and, thus, does not date the Pantano Formation. The middle Tertiary volcanic and sedimentary rocks have an aggregate thickness of 540 m (1,770 ft). We obtained a new 40Ar/ 39Ar age of 26.91+0.18 Ma on biotite sampled at a depth of 2,584-2,609 m (8,478-8,560 ft) from a 169-m-thick (554-ft) silicic tuff in this interval. The volcanic rocks probably correlate with other middle Tertiary volcanic rocks of the area, and the sedimentary rocks may correlate with the Cloudburst and Mineta Formations exposed on the flanks of the San Pedro Basin to the northeast. The Bisbee Group in the Exxon well is 602 m (1,975 f

A new interpretation of seismic tomography in the southern Dead Sea basin using neural network clustering techniques

NASA Astrophysics Data System (ADS)

Braeuer, Benjamin; Bauer, Klaus

2015-11-01

The Dead Sea is a prime location to study the structure and development of pull-apart basins. We analyzed tomographic models of Vp, Vs, and Vp/Vs using self-organizing map clustering techniques. The method allows us to identify major lithologies by their petrophysical signatures. Remapping the clusters into the subsurface reveals the distribution of basin sediments, prebasin sedimentary rocks, and crystalline basement. The Dead Sea basin shows an asymmetric structure with thickness variation from 5 km in the west to 13 km in the east. Most importantly, we identified a distinct, well-defined body under the eastern part of the basin down to 18 km depth. Considering its geometry and petrophysical signature, this unit is interpreted as a buried counterpart of the shallow prebasin sediments encountered outside of the basin and not as crystalline basement. The seismicity distribution supports our results, where events are concentrated along boundaries of the basin and the deep prebasin sedimentary body. Our results suggest that the Dead Sea basin is about 4 km deeper than assumed from previous studies.

Joint Interpretation of Magnetotelluric and Gravimetric Data from the South American Paraná Basin

NASA Astrophysics Data System (ADS)

Santos, E. B.; Santos, H. B.; Vitorello, I.; Pádua, M. B.

2013-05-01

The Paraná Basin is a large sedimentary basin in central-eastern South America that extends through Brazil, Paraguay, Uruguay and Argentina. Evolved completely over the South American continental crust, this Paleozoic basin is filled with sedimentary and volcanic rocks deposited from the Silurian to the Cretaceous, when a significant basaltic effusion covered almost the entire area of the basin. A series of superposed sedimentary and volcanic rock layers were laid down under the influence of different tectonic settings, probably originated from distant collisional dynamics of continental boards that led to the amalgamation of Gondwanaland. The current boundaries of the basin can be the result of issuing erosional or of tectonic origin, such as the building up of large arches and faults. To evaluate the deep structural architecture of the lithosphere under a sedimentary basin is a great challenge, requiring the integration of different geophysical and geological studies. In this paper, we present the resulting Paraná Basin lithospheric model, obtained from processing and inversion of broadband and long-period magnetotelluric soundings along an E-W profile across the central part of the basin, complemented by a qualitative joint interpretation of gravimetric data, in order to obtain a more precise geoelectric model of the deep structure of the region.

The South China - Indochina collision: a perspective from sedimentary basins analysis

NASA Astrophysics Data System (ADS)

Rossignol, Camille; Bourquin, Sylvie; Hallot, Erwan; Poujol, Marc; Roger, Françoise; Dabard, Marie-Pierre; Martini, Rossana; Villeneuve, Michel; Cornée, Jean-Jacques; Peyrotty, Giovan

2017-04-01

Sedimentary basins, through the sedimentary successions and the nature of the deposits, reflect the geology of the area from which the sediments were derived and thus provide valuable record of hinterland tectonism. As the collision between the South China and the Indochina blocks (i.e., the Indosinian orogeny) is still the object of a number of controversies regarding, for instance, its timing and the polarity of the subduction, the sedimentary basins associated with this mountain belt are likely to provide clues to reconstruct its geodynamic evolution. However, both the Sam Nua Basin (located to the south of the inner zones of the Indosinian orogeny and the Song Ma ophiolites) and the Song Da Basin (located to the north of the inner zones), northern Vietnam, are still lacking important information regarding the depositional environments and the ages of the main formations that they contain. Using sedimentological and dating analyses (foraminifers biostratigraphy and U-Pb dating on detrital zircon), we provide a new stratigraphic framework for these basins and propose a geodynamic evolution of the present-day northern Vietnam. During the Early Triassic, the Sam Nua Basin was mainly supplied by volcaniclastic sediments originating from an active volcanic activity. Geochemical investigations, combined with sedimentological and structural analyses, support an arc-related setting for this magmatism. This magmatic arc resulted from the subduction of a south dipping oceanic slab that once separated the South China from the Indochina blocks. During the Middle to the Late Triassic, the Sam Nua Basin underwent erosion that lead to the formation of a major unconformity, termed the Indosinian unconformity. This unconformity is interpreted to result from the erosion of the Indosinian mountain belt, built after the continental collision between the South China and the Indochina blocks. Later, during the Late Triassic, the Sam Nua Basin experienced the deposition of very coarse material, emplaced under continental setting and representing the product of the erosion of the Indosinian mountain belt. To the North, the Song Da Basin is characterized by strongly diachronous deposits over a basal unconformity developed at the expense of volcanic and volcaniclastic deposits related to the Emeishan Large Igneous Province. The sedimentary succession indicates a foreland setting during the Early to the Middle Triassic, which contrasts with the commonly assumed rift setting for these sediments. Thus, the Song Da Basin documents the formation of the Indosinian thrust belt, located immediately to the South of the basin.

Passive margins: U.S. Geological Survey Line 19 across the Georges Bank basin

USGS Publications Warehouse

Klitgord, Kim D.; Schlee, John S.; Grow, John A.; Bally, A.W.

1987-01-01

Georges Bank is a shallow part of the Atlantic continental shelf southeast of New England (Emery and Uchupi, 1972, 1984). This bank, however, is merely the upper surface of several sedimentary basins overlying a block-faulted basement of igneous and metamorphic crystalline rock. Sedimentary rock forms a seaward-thickening cover that has accumulated in one main depocenter and several ancillary depressions, adjacent to shallow basement platforms of paleozoic and older crystalline rock. Georges Bank basin contains a thickness of sedimentary rock greater than 10 km, whereas the basement platforms that flank the basin are areas of thin sediment accumulation (less than 5 km).

Diachronous evolution of volcano-sedimentary basins north of the Congo craton: Insights from U Pb ion microprobe dating of zircons from the Poli, Lom and Yaoundé Groups (Cameroon)

NASA Astrophysics Data System (ADS)

Toteu, Sadrack Félix; Penaye, Joseph; Deloule, Etienne; Van Schmus, William Randall; Tchameni, Rigobert

2006-04-01

Ion microprobe U-Pb dating of zircons from Neoproterozoic volcano-sedimentary sequences in Cameroon north of the Congo craton is presented. For the Poli basin, the depositional age is constrained between 700-665 Ma; detrital sources comprise ca. 920, 830, 780 and 736 Ma magmatic zircons. In the Lom basin, the depositional age is constrained between 613 and 600 Ma, and detrital sources include Archaean to Palaeoproterozoic, late Mesoproterozoic to early Neoproterozoic (1100-950 Ma), and Neoproterozoic (735, 644 and 613 Ma) zircons. The Yaoundé Group is probably younger than 625 Ma, and detrital sources include Palaeoproterozoic and Neoproterozoic zircons. The depositional age of the Mahan metavolcano-sedimentary sequence is post-820 Ma, and detrital sources include late Mesoproterozoic (1070 Ma) and early Neoproterozoic volcanic rocks (824 Ma). The following conclusions can be made from these data. (1) The three basins evolved during the Pan-African event but are significantly different in age and tectonic setting; the Poli is a pre- to syn-collisional basin developed upon, or in the vicinity of young magmatic arcs; the Lom basin is post-collisional and intracontinental and developed on old crust; the tectono-metamorphic evolution of the Yaoundé Group resulted from rapid tectonic burial and subsequent collision between the Congo craton and the Adamawa-Yade block. (2) Late Mesoproterozoic to early Neoproterozoic inheritance reflects the presence of magmatic event(s) of this age in west-central Africa.

Exhumation and stress history in the sedimentary cover during Laramide thick-skinned tectonics assessed by stylolite roughness analysis.

NASA Astrophysics Data System (ADS)

Beaudoin, Nicolas; Lacombe, Olivier; David, Marie-Eléonore; Koehn, Daniel; Coltier, Robin

2017-04-01

Basement-involvement in shortening in forelands has a strong impact on the overlying sedimentary cover. The basement influences namely the geometry of folds and structures, the stress evolution and the nature and pathways for fluid migrations. However, these influences are poorly documented in context where the basement/cover interface is shallow (<6 km). This contribution presents the reconstruction of paleostress and vertical burial history of the Palaeozoic sedimentary strata affected by the Sevier-Laramide deformation at the front of the Rocky Mountains, in the Bighorn Basin (Wyoming, USA). Stylolite populations have been considered as part of an extensive microstructure investigation including also fractures, striated microfaults and calcite twins in key major structures such as the Sheep Mountain Anticline, the Rattlesnake Mountain Anticline, and the Bighorn Mountains Arch. Stylolite recognized in the field are clearly related to successive stages of deformation of the sedimentary cover, including fold development. We further apply a newly developed roughness analysis of pressure-solution stylolites which grant access (1) to the magnitude of the vertical principal stress, hence the maximum burial depth of the strata based on sedimentary stylolites, (2) to the principal stress orientations and regimes based on tectonic stylolites and (3) ultimately to the complete stress tensor when sedimentary and tectonic stylolites can be considered coeval. This approach was then coupled to mechanical properties of main competent formations exposed in the basin. Results of stylolite paleopiezometry, compared and combined to existing paleostress estimates from calcite twins and to exhumation reconstruction from low-temperature thermochronology, unravel the potential of the method to refine the structural history at the structure- and basin-scale. On top of the advances this case study adds to the methodology, the quantified reconstruction of stress-exhumation evolution in such a broken-foreland context offers a unique opportunity to discuss how thick-skinned tectonics impacts stress distribution in the sedimentary cover.

Drilling the centre of the Thuringian Basin, Germany, to decipher potential interrelation between shallow and deep fluid systems

NASA Astrophysics Data System (ADS)

Kukowski, Nina; Totsche, Kai Uwe; Abratis, Michael; Habisreuther, Annett; Ward, Timothy; Influins Drilling-Team

2014-05-01

To shed light on the coupled dynamics of near surface and deep fluids in a sedimentary basin on various scales, ranging from the pore scale to the extent of an entire basin, is of paramount importance to understand the functioning of sedimentary basins fluid systems and therefore e.g. drinking water supply. It is also the fundamental goal of INFLUINS (INtegrated FLuid dynamics IN Sedimentary basins), a research initiative of several groups from Friedrich-Schiller University of Jena and their partners. This research association is focusing on the nearby Thuringian basin, a well confined, small intra-continental sedimentary basin in Germany, as a natural geo laboratory. In a multidisciplinary approach, embracing different fields of geophysics like seismic reflection profiling or airborne geomagnetics, structural geology, sedimentology, hydrogeology, hydrochemistry and hydrology, remote sensing, microbiology and mineralogy, among others, and including both, field-based, laboratory-based and computer-based research, an integral INFLUINS topic is the potential interaction of aquifers within the basin and at its rims. The Thuringian basin, which is composed of sedimentary rocks from the latest Paleozoic and mainly Triassic, is particularly suited to undertake such research as it is of relative small size, about 50 to 100 km, easily accessible, and quite well known from previous studies, and therefore also a perfect candidate for deep drilling. After the acquisition of 76 km seismic reflection data in spring 2011, to get as much relevant data as possible from a deep drilling at the cross point between two seismic profiles with a limited financial budget, an optimated core sampling and measuring strategy including partial coring, borehole geophysics and pump tests as well as a drill hole design, which enables for later continuation of drilling down to the basement, had been developed. Drilling Triassic rocks from Keuper to lower Buntsandstein was successfully realised down to a final depth of 1179 m from late June to mid-September 2013. Here, we give an introduction into the layout of INFLUINS deep drilling together with a summary of preliminary results, e.g. on the nature of the boundaries between Muschelkalk and Buntsandstein, and between upper and middle Buntsandstein, a complete core recovery of upper Buntsandstein saliniferous formations as well as unexpectedly low porosity and permeability of potential aquifers.

Space Station Views of African Sedimentary Basins-Analogs for Subsurface Patterns

NASA Technical Reports Server (NTRS)

Wilkinson, M. Justin

2007-01-01

Views of African sedimentary basins from the International Space Station (ISS) is presented. The images from ISS include: 1) Inland deltas; 2) Prediction; 3) Significance; 4) Exploration applications; and 5) Coastal megafans

Geochronology, Geochemistry and Tectonics of Subduction-Related Late Triassic Rift Basins in Northern Chile (24º-26ºS).

NASA Astrophysics Data System (ADS)

Espinoza, M. E.; Oliveros, V.; Celis, C.

2016-12-01

As plate-tectonic processes ultimately control the location, initiation, and evolution of sedimentary basins, the study of these is crucial to understand the geodynamic framework of a specific period. In northern Chile, Late Triassic depocenters crop out along the Coastal Cordillera and Precordillera. These basins have been typically associated to a continental rifting unrelated to subduction prior to the Andean orogeny. In this work, we characterize these basins and present field and analytical data suggesting the development of these basins during an active subduction system. U-Pb geochronology show the opening of these basins probably during the Anisian-Carnian (>233 Ma) with the deposition of highly mature sediments in fluvial systems, followed by the initiation of the volcanism and associated fluvial-alluvial redeposition. Furthermore, a continental (fluvial and lacustrine) deposition and its transition to shallow marine facies are recorded during the Norian to Raethian (212-200 Ma), contemporaneous with the development of acidic volcanic centers. The sedimentary provenance evidence a main detrital supply of Early Permian age ( 297-283 Ma) corresponding to volcanic and plutonic basement rocks and a minor supply close to 478 Ma related to the exhumed Famatinian arc to the east. Geochemical results from volcanic products present in the basins show a typical subduction signal (calc-alkaline trend, low HFS/LILE ratio and Nb-Ta negative anomalies), while petrography indicate a wide compositional variation more than a bimodal distribution. These basins present half-graben geometries with the recognition of structural highs separating local depocenters. Kinematic analyses carried in synrift extensional faults show a bimodal distribution of the maximum strain axes from a NE-SW to a subordinate NW-SE direction of elongation. This bimodality could be related to the co-existence of two competing strain directions associated to the breakup of Pangea and the presence of a subducting slab. These results integrates the magmatic, sedimentary and tectonic record pointing to a subduction-related extensional basin model developed over a continental substratum. The recognition of this ancient examples are important to understand an actual underrepresented basin setting.

Supercomputer analysis of sedimentary basins.

PubMed

Bethke, C M; Altaner, S P; Harrison, W J; Upson, C

1988-01-15

Geological processes of fluid transport and chemical reaction in sedimentary basins have formed many of the earth's energy and mineral resources. These processes can be analyzed on natural time and distance scales with the use of supercomputers. Numerical experiments are presented that give insights to the factors controlling subsurface pressures, temperatures, and reactions; the origin of ores; and the distribution and quality of hydrocarbon reservoirs. The results show that numerical analysis combined with stratigraphic, sea level, and plate tectonic histories provides a powerful tool for studying the evolution of sedimentary basins over geologic time.

Sedimentary sequence evolution in a Foredeep basin: Eastern Venezuela

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bejarano, C.; Funes, D.; Sarzalho, S.

1996-08-01

Well log-seismic sequence stratigraphy analysis in the Eastern Venezuela Foreland Basin leads to study of the evolution of sedimentary sequences onto the Cretaceous-Paleocene passive margin. This basin comprises two different foredeep sub-basins: The Guarico subbasin to the west, older, and the Maturin sub-basin to the east, younger. A foredeep switching between these two sub-basins is observed at 12.5 m.y. Seismic interpretation and well log sections across the study area show sedimentary sequences with transgressive sands and coastal onlaps to the east-southeast for the Guarico sub-basin, as well as truncations below the switching sequence (12.5 m.y.), and the Maturin sub-basin showsmore » apparent coastal onlaps to the west-northwest, as well as a marine onlap (deeper water) in the west, where it starts to establish. Sequence stratigraphy analysis of these sequences with well logs allowed the study of the evolution of stratigraphic section from Paleocene to middle Miocene (68.0-12.0 m.y.). On the basis of well log patterns, the sequences were divided in regressive-transgressive-regressive sedimentary cycles caused by changes in relative sea level. Facies distributions were analyzed and the sequences were divided into simple sequences or sub- sequences of a greater frequencies than third order depositional sequences.« less

Sedimentary rocks of the coast of Liberia

USGS Publications Warehouse

White, Richard William

1969-01-01

Two basins containing sedimentary rocks o# probable Cretaceous age have been recognized near the coast of Liberia in the area between Monrovia and Buchanan; geophysical evidence suggests that similar though larger basins exist on the adjacent continental shelf. The oldest sedimentary unit recognized, the Paynesville Sandstone of possible early to middle Paleozoic age, is intruded by dikes and sills of diabase of early Jurassic age and lies unconformably on crystalline rocks of late Precambrian age. Dips in the Paynesville Sandstone define a structural basin centered south of Roberts International Airport (formerly called Roberts Field) about 25 miles east of Monrovla. Wackes and conglomerates of Cretaceous age, herein named the Farmington River Formation, unconformably overlie the Paynesville Sandstone and constitute the sedimentary fill in the Roberts basin. The Bassa basin lies to the southeast of the Roberts basin and is separated from it by an upwarp of crystalline rocks. The basin is occupied by wackes and conglomerates of the Farmington River Formation, which apparently lie directly on the crystalline basement. Both basins are bounded on the northeast by northwest-trending dip-slip faults. The best potential for petroleum deposits that exists in Liberia is beneath the adjacent continental shelf and slope. Geophysical exploration and drilling will be required to evaluate this potential.

Sedimentation and tectonics in the southern Bida Basin, Nigeria: depositional response to varying tectonic context

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braide, S.P.

1990-05-01

The Upper Cretaceous Bida basin of central Nigeria is sandwiched between the Precambrian schist belts of the Northern Nigerian massif and the West African craton. Of interest is the southern part of the basin, which developed in continental settings, because the facies architecture of the sedimentary fill suggests a close relation between sedimentation dynamics and basin margin tectonics. This relationship is significant to an understanding of the basin's origin, which has been controversial. A simple sag and rift origin has been suggested, and consequently dominated the negative thinking on the hydrocarbon prospects of the basin which were considered poor. Thismore » detailed study of the facies indicates rapid basin-wide changes from various alluvial fan facies through flood-basin and deltaic facies to lacustrine facies. Paleogeographic reconstruction suggests lacustrine environments were widespread and elongate. Lacustrine environments occurred at the basin's axis and close to the margins. This suggests the depocenter must have migrated during the basin's depositional history and subsided rapidly to accommodate the 3.5-km-thick sedimentary fill. Although distinguishing pull-apart basins from rift basins, based solely on sedimentologic grounds, may be difficult, the temporal migration of the depocenter, as well as the basin architecture of upward coarsening cyclicity, show a strong tectonic and structural overprint that suggests a tectonic framework for the Southern Bida basin similar in origin to a pull-apart basin.« less

Cryogenic formation of brine and sedimentary mirabilite in submergent coastal lake basins, Canadian Arctic

NASA Astrophysics Data System (ADS)

Grasby, Stephen E.; Rod Smith, I.; Bell, Trevor; Forbes, Donald L.

2013-06-01

Two informally named basins (Mirabilite Basins 1 and 2) along a submergent coastline on Banks Island, Canadian Arctic Archipelago, host up to 1 m-thick accumulations of mirabilite (Na2SO4·10H2O) underlying stratified water bodies with basal anoxic brines. Unlike isostatically uplifting coastlines that trap seawater in coastal basins, these basins formed from freshwater lakes that were transgressed by seawater. The depth of the sill that separates the basins from the sea is shallow (1.15 m), such that seasonal sea ice formation down to 1.6 m isolates the basins from open water exchange through the winter. Freezing of seawater excludes salts, generating dense brines that sink to the basin bottom. Progressive freezing increases salinity of residual brines to the point of mirabilite saturation, and as a result sedimentary deposits of mirabilite accumulate on the basin floors. Brine formation also leads to density stratification and bottom water anoxia. We propose a model whereby summer melt of the ice cover forms a temporary freshwater lens, and rather than mixing with the underlying brines, it is exchanged with seawater once the ice plug that separates the basins from the open sea melts. This permits progressive brine development and density stratification within the basins.

Late Cenozoic tectonic activity of the Altyn Tagh range: Constraints from sedimentary records from the Western Qaidam Basin, NE Tibetan Plateau

NASA Astrophysics Data System (ADS)

Zhang, Tao; Fang, Xiaomin; Wang, Yadong; Song, Chunhui; Zhang, Weilin; Yan, Maodu; Han, Wenxia; Zhang, Dawen

2018-07-01

The Altyn Tagh range (ATR) is the northern geological boundary of the Tibetan Plateau and plays a key role in accommodating its Cenozoic lithospheric deformation. However, knowledge of the structural style and age of uplift of the ATR is limited and controversial. The Qaidam Basin, in the southeast side of the ATR, provides an outstanding field laboratory for understanding the history and mechanisms of ATR growth. This study presents a detailed sedimentological analysis of a 1040-m-thick late Cenozoic ( 17-5.0 Ma) sedimentary sequence from the western Qaidam Basin, together with the analysis of sedimentological data from nearby boreholes and sections. Our aims were to determine the spatiotemporal evolution of the sedimentary sequences in the study area and to explore their response to late Cenozoic tectonic activity in the ATR. The results show three major intervals of the sedimentary characteristics in the study area: >17-16 Ma, 10 Ma and <5 Ma, which are closely related to the development of unconformities and growth strata recorded by high-resolution seismic reflection profiles. Combining the results with a comprehensive provenance analysis and with published records of regional climate change and tectonic activity, we discuss the possible factors responsible for the variations in the sedimentary characteristics of the studied sections. We conclude that significant tectonic responses in the western Qaidam Basin during the late Cenozoic were caused by three stages of tectonic activity of the ATR, at >17-16 Ma, 16-10 Ma and 10 Ma, during which the ATR respectively experienced tectonic uplift, fast strike-slip motion and intense uplift.

MODTOHAFSD — A GUI based JAVA code for gravity analysis of strike limited sedimentary basins by means of growing bodies with exponential density contrast-depth variation: A space domain approach

NASA Astrophysics Data System (ADS)

Chakravarthi, V.; Sastry, S. Rajeswara; Ramamma, B.

2013-07-01

Based on the principles of modeling and inversion, two interpretation methods are developed in the space domain along with a GUI based JAVA code, MODTOHAFSD, to analyze the gravity anomalies of strike limited sedimentary basins using a prescribed exponential density contrast-depth function. A stack of vertical prisms all having equal widths, but each one possesses its own limited strike length and thickness, describes the structure of a sedimentary basin above the basement complex. The thicknesses of prisms represent the depths to the basement and are the unknown parameters to be estimated from the observed gravity anomalies. Forward modeling is realized in the space domain using a combination of analytical and numerical approaches. The algorithm estimates the initial depths of a sedimentary basin and improves them, iteratively, based on the differences between the observed and modeled gravity anomalies within the specified convergence criteria. The present code, works on Model-View-Controller (MVC) pattern, reads the Bouguer gravity anomalies, constructs/modifies regional gravity background in an interactive approach, estimates residual gravity anomalies and performs automatic modeling or inversion based on user specification for basement topography. Besides generating output in both ASCII and graphical forms, the code displays (i) the changes in the depth structure, (ii) nature of fit between the observed and modeled gravity anomalies, (iii) changes in misfit, and (iv) variation of density contrast with iteration in animated forms. The code is used to analyze both synthetic and real field gravity anomalies. The proposed technique yielded information that is consistent with the assumed parameters in case of synthetic structure and with available drilling depths in case of field example. The advantage of the code is that it can be used to analyze the gravity anomalies of sedimentary basins even when the profile along which the interpretation is intended fails to bisect the strike length.

Assessment of undiscovered conventional oil and gas resources of the Western Canada Sedimentary Basin, Canada, 2012

USGS Publications Warehouse

Higley, Debra K.

2013-01-01

The U.S. Geological Survey recently completed a geoscience-based assessment of undiscovered oil and gas resources of provinces within the Western Canada Sedimentary Basin. The Western Canada Sedimentary Basin primarily comprises the (1) Alberta Basin Province of Alberta, eastern British Columbia, and the southwestern Northwest Territories; (2) the Williston Basin Province of Saskatchewan, southeastern Alberta, and southern Manitoba; and (3) the Rocky Mountain Deformed Belt Province of western Alberta and eastern British Columbia. This report is part of the U.S. Geological Survey World Petroleum Resources Project assessment of priority geologic provinces of the world. The assessment was based on geoscience elements that define a total petroleum system (TPS) and associated assessment unit(s). These elements include petroleum source rocks (geochemical properties and petroleum generation, migration, and accumulation), reservoir description (reservoir presence, type, and quality), and petroleum traps (trap and seal types, and timing of trap and seal formation relative to petroleum migration). Using this framework, the Elk Point-Woodbend Composite TPS, Exshaw-Fernie-Mannville Composite TPS, and Middle through Upper Cretaceous Composite TPS were defined, and four conventional assessment units within the total petroleum systems were quantitatively assessed for undiscovered resources in the Western Canada Sedimentary Basin.

New Insights into the Provenance of the Southern Junggar Basin in the Jurassic from Heavy Mineral Analysis and Sedimentary Characteristics

NASA Astrophysics Data System (ADS)

Zhou, T. Q.; Wu, C.; Zhu, W.

2017-12-01

Being a vital component of foreland basin of Central-western China, Southern Junggar Basin has observed solid evidences of oil and gas in recent years without a considerable advancement. The key reason behind this is the lack of systematic study on sedimentary provenance analysis of the Southern Junggar basin. Three parts of the Southern Junggar basin, including the western segment (Sikeshu Sag), the central segment (Qigu Fault-Fold Belt) and the eastern segment (Fukang Fault Zone), possess varied provenance systems, giving rise to difficulties for oil-gas exploration. In this study, 3468 heavy minerals data as well as the sedimentary environment analysis of 10 profiles and 7 boreholes were used to investigate the provenances of the deposits in the southern Junggar basin . Based on this research, it reveals that: Sikeshu sag initially shaped the foreland basin prototype in the Triassic and its provenance area of the sediments from the Sikeshu sag has primarily been situated in zhongguai uplift-chepaizi uplift depositional systems located in the northwestern margin of the Junggar Basin. From the early Jurassic, the key sources were likely to be late Carboniferous to early Permain post-collisional volcanic rocks from the North Tian Shan block to Centrao Tian Shan. In the Xishanyao formation, Abundant lithic metamorphic, epidote and garnet that suggests the source rocks were possibly late Carboniferous subduction-related arc volcanic rocks of the Central Tian Shan. In the Toutunhe formation, Bogda Mountains began uplifting and gradually becoming the major provenance. Moreover, the sedimentary boundaries of Junggar basin have also shifted towards the North Tian Shan again. In the late Jurassic, the conglomerates of the Kalazha formation directly overlie the fine-grained red beds of Qigu formation, which throw light on the rapid tectonic uplift of the North Tian Shan. In the eastern segment, meandering river delta and shore-lacustrine environments were fully developed in Badaowan formation indicating that the provenance of sediments mainly derived from the Kelameili Mountains. During the late Jurassic, the rapid uplift of Bogda Mountains could result into the distinct difference in heavy mineral assemblages between the eastern segment and the central segments.

Porous media of the Red River Formation, Williston Basin, North Dakota: a possible Sedimentary Enhanced Geothermal System

NASA Astrophysics Data System (ADS)

Hartig, Caitlin M.

2018-01-01

Fracture-stimulated enhanced geothermal systems (EGS) can be developed in both crystalline rocks and sedimentary basins. The Red River Formation (Ordovician) is a viable site for development of a sedimentary EGS (SEGS) because the formation temperatures exceed 140 °C and the permeability is 0.1-38 mD; fracture stimulation can be utilized to improve permeability. The spatial variations of the properties of the Red River Formation were analyzed across the study area in order to understand the distribution of subsurface formation temperatures. Maps of the properties of the Red River Formation-including depth to the top of the formation, depth to the bottom of the formation, porosity, geothermal gradient, heat flow, and temperature-were produced by the Kriging interpolation method in ArcGIS. In the future, these results may be utilized to create a reservoir simulation model of an SEGS in the Red River Formation; the purpose of this model would be to ascertain the thermal response of the reservoir to fracture stimulation.

Sedimentary Record of the Back-Arc Basins of South-Central Mexico: an Evolution from Extensional Basin to Carbonate Platform.

NASA Astrophysics Data System (ADS)

Sierra-Rojas, M. I.; Molina-Garza, R. S.; Lawton, T. F.

2015-12-01

The Lower Cretaceous depositional systems of southwestern Oaxaquia, in south-central Mexico, were controlled by tectonic processes related to the instauration of a continental arc and the accretion of the Guerrero arc to mainland Mexico. The Atzompa Formation refers to a succession of conglomerate, sandstone, siltstone, and limestone that crop out in southwestern Mexico with Early Cretaceous fauna and detrital zircon maximum depositional ages. The sedimentary record shows a transition from early fluvial/alluvial to shallow marine depositional environments. The first stage corresponds to juvenile fluvial/alluvial setting followed by a deep lacustrine depositional environment, suggesting the early stages of an extensional basin. The second stage is characterized by anabranched deposits of axial fluvial systems flowing to the NE-SE, showing deposition during a period of rapid subsidence. The third and final stage is made of tidal deposits followed, in turn, by abrupt marine flooding of the basin and development of a Barremian-Aptian carbonate ramp. We interpret the Tentzo basin as a response to crustal extension in a back-arc setting, with high rates of sedimentation in the early stages of the basin (3-4 mm/m.y), slower rates during the development of starved fluvial to tidal systems and carbonate ramps, and at the top of the Atzompa Formation an abrupt deepening of the basin due to flexural subsidence related to terrane docking and attendant thrusting to the west. These events were recorded in the back-arc region of a continental convergent margin (Zicapa arc) where syn-sedimentary magmatism is indicated by Early Cretaceous detrital and volcanic clasts from alluvial fan facies west of the basin. Finally, and as a response to the accretion of the Guerrero superterrane to Oaxaquia during the Aptian, a carbonate platform facing toward the Gulf of Mexico was established in central to eastern Oaxaquia.

Alteration mineralogy and geochemistry as an exploration tool for detecting basement heat sources in sedimentary basins

NASA Astrophysics Data System (ADS)

Uysal, Tonguc; Gasparon, Massimo; van Zyl, Jacobus; Wyborn, Doone

2010-05-01

The Cooper Basin located in South Australia and Queensland hosts some of the hottest granites in the world at economic drilling depths (240°C at 3.5 km). Investigating the mechanism of heat-producing element enrichment in the Cooper Basin granite is crucial for understanding hot-dry rock geothermal systems and developing exploration strategies. Trace element (by ICP-MS) and stable isotope geochemistry of whole rock granite samples and hydrothermal phyllosilicate alteration minerals separated from the granite and overlying sandstones and mudstones of the Cooper Basin were examined in detail. Granite core samples from relatively shallow depths in Moomba 1 and Big Lake 1 are strongly altered with pervasive sericite (illite) and quartz precipitation, probably associated with intense micro-fracturing and veining. The intensity of hydrothermal alteration is less in deeper samples from Mcleod 1, Jolokia and Habanero 1. Highly altered granites from former holes are substantially enriched in lithophile elements, particularly in Cs, Rb, Be, Th, U and rare earth elements (REE) relative to the upper continental crust (UCC). U and Th contents with concentrations of up to 30 and 144 ppm, respectively, are 10 and 13 times higher than those of the UCC. Comparison of the trace element composition of the same samples dissolved by open beaker acid digestion and high-pressure acid bomb digestion (to dissolve zircon) shows that zircon is not the main repository of U and Th in the Cooper Basin granite. Instead, we propose that the enrichment of heat-producing elements was promoted by a regional hydrothermal event leading to the precipitation of U and Th- bearing minerals such as illite, K-feldspar and thorite. Crystallinity index (illite crystallinity) of the sericite indicates hydrothermal temperatures ranging from 250°C (in Moomba 1 and Big Lake 1) to 350°C (in McLeod 1 and Jolokia 1). In the overlying sedimentary rocks, crystallinity of authigenic illites translates to lower crystallisation temperatures (150-200°C). Normalised REE patterns of the mostly altered granite samples show a strong negative Ce anomaly, signifying oxidation of trivalent Ce to less soluble tetravalent Ce. Oxygen and hydrogen isotope compositions of illites from the granites and sedimentary rocks are very similar, with d18O = -1.8 per mill to +2.7 per mill; δD = -99 per mill to -121 per mill for granites and d18O = +2.3 per mill to +9.7 per mill, dD = -78 per mill to -119 per mill for sedimentary rocks. The calculated oxygen and hydrogen isotope compositions of fluids in equilibrium with the illites are depleted in 18O and deuterium, comparable to those of waters reported for most high-latitude sedimentary basins. Hence, stable isotope data of alteration minerals in the granite and the overlying sedimentary rocks suggest the operation of a hydrothermal system involving high latitude meteoric waters during extensional tectonism in the Cooper Basin region. Investigation of alteration mineralogy and geochemistry of relatively shallow sedimentary sections (generally intersected in previously drilled petroleum holes) represents a potentially strong tool to evaluate the presence of a geothermal heat source in the basement of sedimentary basins.

Hydrogeologic framework and estimates of groundwater storage for the Hualapai Valley, Detrital Valley, and Sacramento Valley basins, Mohave County, Arizona

USGS Publications Warehouse

Truini, Margot; Beard, L. Sue; Kennedy, Jeffrey; Anning, Dave W.

2013-01-01

We have investigated the hydrogeology of the Hualapai Valley, Detrital Valley, and Sacramento Valley basins of Mohave County in northwestern Arizona to develop a better understanding of groundwater storage within the basin fill aquifers. In our investigation we used geologic maps, well-log data, and geophysical surveys to delineate the sedimentary textures and lithology of the basin fill. We used gravity data to construct a basin geometry model that defines smaller subbasins within the larger basins, and airborne transient-electromagnetic modeled results along with well-log lithology data to infer the subsurface distribution of basin fill within the subbasins. Hydrogeologic units (HGUs) are delineated within the subbasins on the basis of the inferred lithology of saturated basin fill. We used the extent and size of HGUs to estimate groundwater storage to depths of 400 meters (m) below land surface (bls). The basin geometry model for the Hualapai Valley basin consists of three subbasins: the Kingman, Hualapai, and southern Gregg subbasins. In the Kingman subbasin, which is estimated to be 1,200 m deep, saturated basin fill consists of a mixture of fine- to coarse-grained sedimentary deposits. The Hualapai subbasin, which is the largest of the subbasins, contains a thick halite body from about 400 m to about 4,300 m bls. Saturated basin fill overlying the salt body consists predominately of fine-grained older playa deposits. In the southern Gregg subbasin, which is estimated to be 1,400 m deep, saturated basin fill is interpreted to consist primarily of fine- to coarse-grained sedimentary deposits. Groundwater storage to 400 m bls in the Hualapai Valley basin is estimated to be 14.1 cubic kilometers (km3). The basin geometry model for the Detrital Valley basin consists of three subbasins: northern Detrital, central Detrital, and southern Detrital subbasins. The northern and central Detrital subbasins are characterized by a predominance of playa evaporite and fine-grained clastic deposits; evaporite deposits in the northern Detrital subbasin include halite. The northern Detrital subbasin is estimated to be 600 m deep and the middle Detrital subbasin is estimated to be 700 m deep. The southern Detrital subbasin, which is estimated to be 1,500 m deep, is characterized by a mixture of fine- to coarse-grained basin fill deposits. Groundwater storage to 400 m bls in the Detrital Valley basin is estimated to be 9.8 km3. The basin geometry model for the Sacramento Valley basin consists of three subbasins: the Chloride, Golden Valley, and Dutch Flat subbasins. The Chloride subbasin, which is estimated to be 900 m deep, is characterized by fine- to coarse-grained basin fill deposits. In the Golden Valley subbasin, which is elongated north-south, and is estimated to be 1,300 m deep, basin fill includes fine-grained sedimentary deposits overlain by coarse-grained sedimentary deposits in much of the subbasin. The Dutch Flat subbasin is estimated to be 2,600 m deep, and well-log lithologic data suggest that the basin fill consists of interlayers of gravel, sand, and clay. Groundwater storage to 400 m bls in the Sacramento Valley basin is estimated to be 35.1 km3.

Complex Rayleigh Waves Produced by Shallow Sedimentary Basins and their Potential Effects on Mid-Rise Buildings

NASA Astrophysics Data System (ADS)

Kohler, M. D.; Castillo, J.; Massari, A.; Clayton, R. W.

2017-12-01

Earthquake-induced motions recorded by spatially dense seismic arrays in buildings located in the northern Los Angeles basin suggest the presence of complex, amplified surface wave effects on the seismic demand of mid-rise buildings. Several moderate earthquakes produced large-amplitude, seismic energy with slow shear-wave velocities that cannot be explained or accurately modeled by any published 3D seismic velocity models or by Vs30 values. Numerical experiments are conducted to determine if sedimentary basin features are responsible for these rarely modeled and poorly documented contributions to seismic demand computations. This is accomplished through a physics-based wave propagation examination of the effects of different sedimentary basin geometries on the nonlinear response of a mid-rise structural model based on an existing, instrumented building. Using two-dimensional finite-difference predictive modeling, we show that when an earthquake focal depth is near the vertical edge of an elongated and relatively shallow sedimentary basin, dramatically amplified and complex surface waves are generated as a result of the waveguide effect introduced by this velocity structure. In addition, for certain source-receiver distances and basin geometries, body waves convert to secondary Rayleigh waves that propagate both at the free-surface interface and along the depth interface of the basin that show up as multiple large-amplitude arrivals. This study is motivated by observations from the spatially dense, high-sample-rate acceleration data recorded by the Community Seismic Network, a community-hosted strong-motion network, currently consisting of hundreds of sensors located in the southern California area. The results provide quantitative insight into the causative relationship between a sedimentary basin shape and the generation of Rayleigh waves at depth, surface waves at the free surface, scattered seismic energy, and the sensitivity of building responses to each of these.

Gravity study of Libya;Evaluation and Integration with Geological Data

NASA Astrophysics Data System (ADS)

Ben Suleman, abdunnur; Saheel, Ahmed

2016-04-01

Libya is located on the Mediterranean foreland of the African Shield and covers an area of approximately 1.8 million square kilometers. Since Early Paleozoic time, Libya has been a site of deposition of large sheets of continental clastics and several transgressions and regressions by the seas with consequent accumulations of a wide variety of sedimentary rocks. Several tectonic cycles affected the area and shaped the geological setting of the country. However, the regional geology and the structural framework have been highly influenced by the Caledonian, Hercynian, and Alpine tectonic events. As a result, a total of seven sedimentary basins, namely Ghadames, Murzuq, Al Kufra, Al Butnan, Sirt, and the Offshore Pelagian Basin, were developed and were separated by intervening uplifts and platforms ( Gargaf, Tibesti, Nafusah and Cyrenaica platform). Apart from Sirt and the offshore basins, all the above mentioned basins are active since Early Paleozoic time and received several thousand feet of sediments. The capability of providing regional information on the structure of sedimentary basins makes gravity mapping, in conjunction with geological information, potentially powerful tools. In this study we used gravity mapping as our primary tool of investigation however, we also used all available geological information to better understand the regional tectonics. The gravity dataset that were used in the Gravity compilation project of Libya is not homogenous. As a result, some irregularities, apparent spikes or misties, and large shifts were obtained and were taken into consideration. Evaluation of gravity Maps of Libya and their integration with geological data provide a better understanding of the role that gravity mapping plays in the geological exploration of sedimentary basins. Results confirm the known Sirt Basin regional tectonic elements and the possible presence of NW-SE lateral wrench tectonics, crossing Ajdabiya Trough at the center of Sirt Basin. The residual gravity map supports new interpretation of the Sirwal Trough in Northern Cyrenaica. Results also indicate shallow crust along the present day coast line of Al Jabal Al Akhdar, steeply dipping toward the offshore. The depo-center of Ghadames Basin cannot be precisely defined due to the lack of gravity coverage. However, Murzuq Basin is well defined regionally, in spite of gravity gaps which make the overall coverage in the southern basins inadequate for precise interpretation.

Facies architecture and paleohydrology of a synrift succession in the Early Cretaceous Choyr Basin, southeastern Mongolia

USGS Publications Warehouse

Ito, M.; Matsukawa, M.; Saito, T.; Nichols, D.J.

2006-01-01

The Choyr Basin is one of several Early Cretaceous rift basins in southwestern Mongolia that developed in specific regions between north-south trending fold-and-thrust belts. The eastern margin of the basin is defined by high-angle normal and/or strike-slip faults that trend north-to-south and northeast-to-southwest and by the overall geometry of the basin, which is interpreted to be a half graben. The sedimentary succession of the Choyr Basin documents one of the various types of tectono-sedimentary processes that were active in the rift basins of East Asia during Early Cretaceous time. The sedimentary infill of the Choyr Basin is newly defined as the Khalzan Uul and Khuren Dukh formations based on detailed mapping of lateral and vertical variations in component lithofacies assemblages. These two formations are heterotopic deposits and constitute a third-order fluvio-lacustrine sequence that can be divided into transgressive and highstand systems tracts. The lower part of the transgressive systems tract (TST) is characterized by sandy alluvial-fan and braided-river systems on the hanging wall along the western basin margin, and by a gravelly alluvial-fan system on the footwall along the eastern basin margin. The alluvial-fan and braided-river deposits along the western basin margin are fossiliferous and are interpreted to have developed in association with a perennial fluvial system. In contrast, alluvial-fan deposits along the eastern basin margin do not contain any distinct faunas or floras and are interpreted to have been influenced by a high-discharge ephemeral fluvial system associated with fluctuations in wetting and drying paleohydrologic processes. The lower part of the TST deposit fines upward to siltstone-dominated flood-plain and ephemeral-lake deposits that constitute the upper part of the TST and the lower part of the highstand systems tract (HST). These mudstone deposits eventually reduced the topographic irregularities typical of the early stage of synrift basin development, with an associated decrease in topographic-slope gradients. Finally, a high-sinuosity meandering river system drained to the south during the late highstand stage in response to the northward migration of the depocenter. The upper HST deposits are also fossiliferous and are interpreted to have been influenced by a perennial fluvial system, although the average annual discharge of this system was probably less than 5 percent of that involved in the formation of the lower TST deposits along the western basin margin. ?? 2006 Elsevier Ltd. All rights reserved.

Crustal characteristic variation in the central Yamato Basin, Japan Sea back-arc basin, deduced from seismic survey results

NASA Astrophysics Data System (ADS)

Sato, Takeshi; No, Tetsuo; Miura, Seiichi; Kodaira, Shuichi

2018-02-01

The crustal structure of the Yamato Bank, the central Yamato Basin, and the continental shelf in the southern Japan Sea back-arc basin is obtained based on a seismic survey using ocean bottom seismographs and seismic shot to elucidate the back-arc basin formation processes. The central Yamato Basin can be divided into three domains based on the crustal structure: the deep basin, the seamount, and the transition domains. In the deep basin domain, the crust without the sedimentary layer is about 12-13 km thick. Very few units have P-wave velocity of 5.4-6.0 km/s, which corresponds to the continental upper crust. In the seamount and transition domains, the crust without the sedimentary layer is about 12-16 km thick. The P-wave velocities of the upper and lower crusts differs among the deep basin, the seamount, and the transition domains. These results indicate that the central Yamato Basin displays crustal variability in different domains. The crust of the deep basin domain is oceanic in nature and suggests advanced back-arc basin development. The seamount domain might have been affected by volcanic activity after basin opening. In the transition domain, the crust comprises mixed characters of continental and oceanic crust. This crustal variation might represent the influence of different processes in the central Yamato Basin, suggesting that crustal development was influenced not only by back-arc opening processes but also by later volcanic activity. In the Yamato Bank and continental shelf, the upper crust has thickness of about 17-18 km and P-wave velocities of 3.3-4.1 to 6.6 km/s. The Yamato Bank and the continental shelf suggest a continental crustal character.

Dynamic Passage of Topography Beneath the Southern Costa Rica Forearc seen with Seismic Stratigraphy

NASA Astrophysics Data System (ADS)

Edwards, J. H.; Kluesner, J. W.; Silver, E. A.

2014-12-01

3D seismic reflection data (CRISP) collected across the southern Costa Rica margin reveals that a thick, deforming sedimentary wedge underlies the younger slope sediments (Silver et al., this meeting). The older wedge material and younger slope sediments are separated by a high-amplitude regional unconformity. Seismic stratigraphy of the sedimentary strata overlying this regional unconformity reflects a dynamic deformation history of the margin. The younger slope sediments contain series of more localized unconformities, separating sedimentary units as thick as 1 km that reveal a dynamically changing set of inverted, overlapping basins. The geometry of these overlapping, inverted basins indicate sequential uplift events. The direction of basin thickening varies upsection, and these basins are cut by both thrust and normal faults and are deformed by folding. Structural development appears to be controlled by relief on the subducting plate interface, which induces uplift and subsidence and thereby controls the pattern of erosion and deposition. We interpret the evolution of these inverted stratigraphic packages as forming from subducting topography. Correlating these seismic-stratigraphic packages to recent drilling based on preliminary magnetostratigraphy from IODP site U1413 (Expedition 344 Scientists, 2013), allows us to date the passage of the subducting plate topography beginning ~2 Ma.

Response of groundwater level and surface-water/groundwater interaction to climate variability: Clarence-Moreton Basin, Australia

NASA Astrophysics Data System (ADS)

Cui, Tao; Raiber, Matthias; Pagendam, Dan; Gilfedder, Mat; Rassam, David

2018-03-01

Understanding the response of groundwater levels in alluvial and sedimentary basin aquifers to climatic variability and human water-resource developments is a key step in many hydrogeological investigations. This study presents an analysis of groundwater response to climate variability from 2000 to 2012 in the Queensland part of the sedimentary Clarence-Moreton Basin, Australia. It contributes to the baseline hydrogeological understanding by identifying the primary groundwater flow pattern, water-level response to climate extremes, and the resulting dynamics of surface-water/groundwater interaction. Groundwater-level measurements from thousands of bores over several decades were analysed using Kriging and nonparametric trend analysis, together with a newly developed three-dimensional geological model. Groundwater-level contours suggest that groundwater flow in the shallow aquifers shows local variations in the close vicinity of streams, notwithstanding general conformance with topographic relief. The trend analysis reveals that climate variability can be quickly reflected in the shallow aquifers of the Clarence-Moreton Basin although the alluvial aquifers have a quicker rainfall response than the sedimentary bedrock formations. The Lockyer Valley alluvium represents the most sensitively responding alluvium in the area, with the highest declining (-0.7 m/year) and ascending (2.1 m/year) Sen's slope rates during and after the drought period, respectively. Different surface-water/groundwater interaction characteristics were observed in different catchments by studying groundwater-level fluctuations along hydrogeologic cross-sections. The findings of this study lay a foundation for future water-resource management in the study area.

Sedimentary geology of the middle Carboniferous of the Donbas region (Dniepr-Donets Basin, Ukraine).

PubMed

van Hinsbergen, Douwe J J; Abels, Hemmo A; Bosch, Wolter; Boekhout, Flora; Kitchka, Alexander; Hamers, Maartje; van der Meer, Douwe G; Geluk, Mark; Stephenson, Randell A

2015-03-20

The Paleozoic Dniepr-Donets Basin in Belarus, Ukraine, and Russia forms a major hydrocarbon province. Although well- and seismic data have established a 20 km thick stratigraphy, field-studies of its sediments are scarce. The inverted Donbas segment (Ukraine) exposes the middle Carboniferous part of the basin's stratigraphy. Here, we provide detailed sedimentological data from 13 sections that cover 1.5 of the total of 5 km of the Bashkirian and Moscovian stages and assess the paleoenvironment and paleo-current directions. Middle Carboniferous deposition occurred in a shelf environment, with coal deposition, subordinate fluvial facies, and abundant lower and middle shoreface facies, comprising an intercalated package of potential source and reservoir rocks. Sedimentary facies indicate a paleodepth range from below storm wave base to near-coastal swamp environments. Sedimentation and subsidence were hence in pace, with subtle facies changes likely representing relative sea-level changes. Paleocurrent directions are remarkably consistently southeastward in time and space in the different sedimentary facies across the Donbas Fold Belt, illustrating a dominant sedimentary infill along the basin axis, with little basin margin influence. This suggests that the middle Carboniferous stratigraphy of the Dniepr-Donets basin to the northwest probably contains significant amounts of fluvial sandstones, important for assessing hydrocarbon reservoir potential.

Sedimentary geology of the middle Carboniferous of the Donbas region (Dniepr-Donets basin, Ukraine)

PubMed Central

van Hinsbergen, Douwe J. J.; Abels, Hemmo A.; Bosch, Wolter; Boekhout, Flora; Kitchka, Alexander; Hamers, Maartje; van der Meer, Douwe G.; Geluk, Mark; Stephenson, Randell A.

2015-01-01

The Paleozoic Dniepr-Donets Basin in Belarus, Ukraine, and Russia forms a major hydrocarbon province. Although well- and seismic data have established a 20 km thick stratigraphy, field-studies of its sediments are scarce. The inverted Donbas segment (Ukraine) exposes the middle Carboniferous part of the basin's stratigraphy. Here, we provide detailed sedimentological data from 13 sections that cover 1.5 of the total of 5 km of the Bashkirian and Moscovian stages and assess the paleoenvironment and paleo-current directions. Middle Carboniferous deposition occurred in a shelf environment, with coal deposition, subordinate fluvial facies, and abundant lower and middle shoreface facies, comprising an intercalated package of potential source and reservoir rocks. Sedimentary facies indicate a paleodepth range from below storm wave base to near-coastal swamp environments. Sedimentation and subsidence were hence in pace, with subtle facies changes likely representing relative sea-level changes. Paleocurrent directions are remarkably consistently southeastward in time and space in the different sedimentary facies across the Donbas Fold Belt, illustrating a dominant sedimentary infill along the basin axis, with little basin margin influence. This suggests that the middle Carboniferous stratigraphy of the Dniepr-Donets basin to the northwest probably contains significant amounts of fluvial sandstones, important for assessing hydrocarbon reservoir potential. PMID:25791400

The integration of gravity, magnetic and seismic data in delineating the sedimentary basins of northern Sinai and deducing their structural controls

NASA Astrophysics Data System (ADS)

Selim, El Sayed Ibrahim

2016-01-01

The Sinai Peninsula is a part of the Sinai sub-plate that located between the southeast Nubian-Arabian shield and the southeastern Mediterranean northward. The main objectives of this investigation are to deduce the main sedimentary basin and its subdivisions, identify the subsurface structural framework that affects the study area and determine the thickness of sedimentary cover of the basement surface. The total intensity magnetic map, Bouguer gravity map and seismic data were used to achieve the study aims. Structural interpretation of the gravity and magnetic data were done by applying advanced processing techniques. These techniques include; Reduce to the pole (RTP), Power spectrum, Tile derivative and Analytical Signal techniques were applied on gravity and magnetic data. Two dimensional gravity and magnetic modeling and interpretation of seismic sections were done to determine the thickness of sedimentary cover of the study area. The integration of our interpretation suggests that, the northern Sinai area consists of elongated troughs that contain many high structural trends. Four major structural trends have been identified, that, reflecting the influence of district regional tectonic movements. These trends are: (1) NE-SW trend; (2) NNW-SSE trend; (3) ENE-WSW trend and (4) WNW-ESE trend. There are also many minor trends, E-W, NW-SE and N-S structural trends. The main sedimentary basin of North Sinai is divided into four sub-basins; (1) Northern Maghara; (2) Northeastern Sinai; (3) Northwestern Sinai and (4) Central Sinai basin. The sedimentary cover ranges between 2 km and 7 km in the northern part of the study area.

The Nordkapp Basin, Norway: Development of salt and sediment interplays for hydrocarbon exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lerche, I.; Toerudbakken, B.O.

1996-12-31

Investigation of a particular salt diapir in the Nordkapp Basin, Barents Sea has revealed the following sequence of events: (1) salt started to rise when approximately 1.5 {+-} 0.3 km of sedimentary cover was present (Carboniferous/Permian time); (2) salt reached the sediment surface when about 3.5 {+-} 0.7 km of sediment had been deposited (Triassic time); (3) the mushroom cap on the salt stock top developed over a period of about 75--100 Ma (i.e. during the time when about another km of sediment had been deposited) (Triassic through Base Cretaceous time); (4) the mushroom cap started to dip down significantlymore » ({approximately}1 km) into the sediments around Cretaceous to Tertiary erosion time; (5) oil generation started in the deep sediments of the Carboniferous around the time that salt reached the surface (Triassic time) and continues to the present day at sedimentary depths between about 4 to 7 km (currently Triassic and deeper sediments); (6)gas generation started around mushroom cap development time and continues to the present day at sedimentary depths greater than about 6--7 km (Permian/Carboniferous); (7) the salt stock is currently 3--4 km wide, considerably less than the mushroom cap which is 9 km wide and 1 km thick. The relative timing of mushroom cap development, bed upturning, and hydrocarbon generation makes the salt diapir an attractive exploration target, with suggested reservoir trapping under the downturned mushroom cap on the deep basin side of the salt. In addition, rough estimates of rim syncline fill suggest the basin had an original salt thickness of 2.4--3.3 km, depending upon the amount of salt removed at the Tertiary erosion event.« less

Comparing The North-east German Basin With The Polish Basin, Influenced By Major Crustal Fractures

NASA Astrophysics Data System (ADS)

Lamarche, J.; Scheck, M.; Otto, V.; Bayer, U.; Lewerenz, B.

The North-East German Basin (NEGB) and the Polish Basin (PB) are two intraplate sedimentary basins in Central Europe, the development of which was controlled by deep crustal structures: the Elbe Fault System and the Teisseyre-Tornquist Zone, re- spectively. 3D structural models performed separately for each basin led to indepen- dent interpretations showing major similarities, but also significant differences. The outlook of the comparison between the NEGB and the PB is to lead to a joined 3D structural model, which allows reconstructing the synthetic geodynamic evolution of the area. The NEGB and PB are NW-SE-oriented. Both were initiated during Late Carboniferous and Lower Permian, when the post-Variscan rifting affected the com- posite Palaeozoic basement of Central Europe. During Triassic to Cretaceous times, both basins evolved due to thermal subsidence and pulses of tectonic subsidence. At the end of Cretaceous, the basins were tectonically inverted. The sedimentary succes- sions of the NEGB and PB are comparable. Particularly, the Zechstein salt induced comparable sedimentary structures and provided a decoupling level between pre- and post-Zechstein rocks during the Late Cretaceous tectonic inversion in both basins. At the crustal scale, both basins are presently limited to the SW by the NW-SE-oriented Elbe Fault System, that correlates with a positive gravity anomaly. Finally, both basins show a N-S differentiation regarding the detailed subsidence history, the structural set- ting and the salt pattern. In spite of the very similar tectonic evolution of the NEGB and the PB, their large-scale geometry and inversion-related structures are different. The NEGB is asymmetric with a shallow northern slope and a steep bounding fault at the SW margin (Elbe Fault System). In the NEGB, the Late Cretaceous tectonic inversion resulted in asymmetric uplift of the SW' border along the Elbe Fault Sys- tem, and in decreasing deformation in the cover towards North. In contrast, the PB is a symmetric basin, that developed above the Teisseyre-Tornquist Zone. The tectonic inversion resulted in a rather symmetric swell, uplifted along the axis of the former basin. The occurrence and rejuvenation of the deep-seated Teisseyre-Tornquist Zone is held responsible for the symmetry of the PB during its development and later inver- sion, whereas the reactivation of the Elbe Fault Zone induced asymmetric deformation in the Mesozoic cover at the SW margin of the NEGB.

A study of uranium favorability of Cenozoic sedimentary rocks, Basin and Range Province, Arizona: Part I, General geology and chronology of pre-late Miocene Cenozoic sedimentary rocks

USGS Publications Warehouse

Scarborough, Robert Bryan; Wilt, Jan Carol

1979-01-01

This study focuses attention on Cenozoic sedimentary rocks in the Basin and Range Province of Arizona. The known occurrences of uranium and anomalous radioactivity in these rocks are associated with sediments that accumulated in a low energy environment characterized by fine-grained clastics, including important tuffaceous materials, and carbonate rocks. Most uranium occurrences, in these rocks appear to be stratabound. Emphasis was placed on those sedimentary materials that pre-date the late Cenozoic Basin and Range disturbance. They are deformed and crop out on pedimented range blocks and along the province interface with the Transition Zone. Three tentative age groups are recognized: Group I - Oligocene, pre-22 m.y., Group II - early Miocene - 22 m.y. - 16 m.y., and Group III - middle Miocene - 16 m.y. to 13--10 m.y. Regionally, these three groups contain both coarse to fine-grained red clastics and low energy lighter colored 'lacustrine' phases. Each of the three groups has been the object of uranium exploration. Group II, the early Miocene strata, embraces the Anderson Mine - Artillery region host rocks and also the New River - Cave Creek early Miocene beds-along the boundary with the Transition Zone. These three groups of rocks have been tectonically deformed to the extent that original basins of deposition cannot yet be reconstructed. However, they were considerably more extensive in size than the late Cenozoic basins the origin of which deformed the former. Group II rocks are judged to be of prime interest because of: (1) the development and preservation of organic matter in varying lithologies, (2) apparent contemporaneity with silicic volcanic centers, (3) influence of Precambrian crystalline rocks, and (4) relative outcrop continuity near the stable Transition Zone. The Transition Zone, especially along its boundary with the Basin and Range Province, needs additional geologic investigation, especially as regards the depositional continuity of Group II sediment s.

Reactive Transport Modeling Investigation of High Dissolved Sulfide Concentrations in Sedimentary Basin Rocks

NASA Astrophysics Data System (ADS)

Xie, M.; Mayer, U. K.; MacQuarrie, K. T. B.

2017-12-01

Water with total dissolved sulfide in excess of 1 mmol L-1is widely found in groundwater at intermediate depths in sedimentary basins, including regions of the Michigan basin in southeastern Ontario, Canada. Conversely, at deeper and shallower depths, relatively low total dissolved sulfide concentrations have been reported. The mechanisms responsible for the occurrence of these brackish sulfide-containing waters are not fully understood. Anaerobic microbial sulfate reduction is a common process resulting in the formation of high sulfide concentrations. Sulfate reduction rates depend on many factors including the concentration of sulfate, the abundance of organic substances, redox conditions, temperature, salinity and the species of sulfate reducing bacteria (SRB). A sedimentary basin-specific conceptual model considering the effect of salinity on the rate of sulfate reduction was developed and implemented in the reactive transport model MIN3P-THCm. Generic 2D basin-scale simulations were undertaken to provide a potential explanation for the dissolved sulfide distribution observed in the Michigan basin. The model is 440 km in the horizontal dimension and 4 km in depth, and contains fourteen sedimentary rock units including shales, sandstones, limestones, dolostone and evaporites. The main processes considered are non-isothermal density dependent flow, kinetically-controlled mineral dissolution/precipitation and its feedback on hydraulic properties, cation exchange, redox reactions, biogenic sulfate reduction, and hydromechanical coupling due to glaciation-deglaciation events. Two scenarios were investigated focusing on conditions during an interglacial period and the transient evolution during a glaciation-deglaciation cycle. Inter-glaciation simulations illustrate that the presence of high salinity brines strongly suppress biogenic sulfate reduction. The transient simulations show that glaciation-deglaciation cycles can have an impact on the maximum depth of elevated sulfide concentrations due to freshwater ingress and enhanced mixing. In all simulations the highest concentrations of total sulfide occur at depths of approximately 150 m, while concentrations at depths greater than 300 m typically remain below 0.03 mmol L-1, comparing well with observational data.

Methane on the Move: natural greenhouse gas emissions over geological time

NASA Astrophysics Data System (ADS)

Horsfield, B.; di Primio, R.; Kroeger, K. F.; Schicks, J. M.

2008-12-01

The mass of organic carbon in sedimentary basins amounts to a staggering 1016 tons, dwarfing the mass contained in coal, oil, gas and all living systems by ten thousand-fold. The changing fate of this giant mass during subsidence and uplift, via chemical, physical and biological processes, is known to ultimately control fossil energy resource occurrence worldwide. But what has been overlooked and/or ignored until now is its enormous capacity for driving global climate: only a tiny degree of leakage, particularly when focussed through the clathrate cycle, can result in high greenhouse gas emissions. Understanding the workings of sedimentary basins in time and space is fundamental to gaining insights into Earth's climate. Here we shall present an integrated framework based on petroleum system modelling that will ultimately quantify methane migration and emission from one hundred of the world's most prolific petroliferous sedimentary basins. Timing of hydrocarbon generation from globally occurring prolific Jurassic and Cretaceous source rocks is regarded to be the key factor in quantifying gas release. Combined thermogenic and biogenic methane fluxes are the base for prediction of gas hydrate formation through time and space, by application of kinetics developed in the laboratory to geological scenarios. Results are calibrated in basin scale by emission structure evaluation (mud volcanoes, carbonate mounds, pockmarks) and on a global scale by proxy data from sedimentary archives and local atmospheric data. Identifying potential climate feedback processes over a geological time line that spans the Cenozoic requires a comprehensive understanding of source-sink relationships by coupling these feedstock fluxes with gas hydrate stability considerations, deep biosphere activity, ocean and atmosphere modelling

Preliminary three-dimensional geohydrologic framework of the San Antonio Creek Groundwater Basin, Santa Barbara County, California

NASA Astrophysics Data System (ADS)

Cromwell, G.; Sweetkind, D. S.; O'leary, D. R.

2017-12-01

The San Antonio Creek Groundwater Basin is a rural agricultural area that is heavily dependent on groundwater to meet local water demands. The U.S. Geological Survey (USGS) is working cooperatively with Santa Barbara County and Vandenberg Air Force Base to assess the quantity and quality of the groundwater resources within the basin. As part of this assessment, an integrated hydrologic model that will help stakeholders to effectively manage the water resources in the basin is being developed. The integrated hydrologic model includes a conceptual model of the subsurface geology consisting of stratigraphy and variations in lithology throughout the basin. The San Antonio Creek Groundwater Basin is a relatively narrow, east-west oriented valley that is structurally controlled by an eastward-plunging syncline. Basin-fill material beneath the valley floor consists of relatively coarse-grained, permeable, marine and non-marine sedimentary deposits, which are underlain by fine-grained, low-permeability, marine sedimentary rocks. To characterize the system, surficial and subsurface geohydrologic data were compiled from geologic maps, existing regional geologic models, and lithology and geophysical logs from boreholes, including two USGS multiple-well sites drilled as part of this study. Geohydrologic unit picks and lithologic variations are incorporated into a three-dimensional framework model of the basin. This basin (model) includes six geohydrologic units that follow the structure and stratigraphy of the area: 1) Bedrock - low-permeability marine sedimentary rocks; 2) Careaga Formation - fine to coarse grained near-shore sandstone; 3) Paso Robles Formation, lower portion - sandy-gravely deposits with clay and limestone; 4) Paso Robles Formation, middle portion - clayey-silty deposits; 5) Paso Robles Formation, upper portion - sandy-gravely deposits; and 6) recent Quaternary deposits. Hydrologic data show that the upper and lower portions of the Paso Robles Formation are the primary grou­ndwater-bearing units within the basin, and that the fine-grained layer within this Formation locally restricts vertical groundwater flow.

Evolution of a Miocene sag basin in the Alboran Sea

NASA Astrophysics Data System (ADS)

Do Couto, D.; Gorini, C.; Jolivet, L.; Letouzey, J.; Smit, J.; d'Acremont, E.; Auxietre, J. L.; Le Pourhiet, L.; Estrada, F.; Elabassi, M.; Ammar, A.; Jabour, H.; Vendeville, B.

2012-04-01

The Alboran domain represents the westernmost termination of the peri-Mediterranean Alpine orogen. Its arcuate shape, delimited to the North by the Betic range and to the South by the Rif range, is the result of subduction, collision and slab migration processes. During the Neogene, several sedimentary basins formed on the Betics metamorphic basement, mainly due to the extensional collapse of the previously thickened crust of the Betic-Rif belt. The major sedimentary depocentre, the Western Alboran Basin (WAB), is surrounded by the Gibraltar arc, the volcanic Djibouti mounts and the Alboran ridge, and is partly affected by shale tectonics and associated mud volcanism. High-quality 2-D seismic profiles acquired along the Moroccan margin during the last decade reveal a complete history of the basin. Our study deals with the analysis of seismic profiles oriented parallel and orthogonal to the Mediterranean Moroccan margin. The stratigraphy was calibrated using well data from offshore Spain and Morocco. Our study focuses particularly on the tectono-stratigraphic reconstruction of the basin. The formation of the WAB began in the Early Miocene (Aquitanian - Burdigalian). A massive unit of Early Miocene to Lower Langhian shales and olistostromes forms a thick mobile décollement layer that controls and accommodates deformation of the basin fill. From the Upper Langhian to the Upper Tortonian, the basin is filled by a thick sequence of siliciclastic deposits. Stratigraphic geometries identified on seismic data clearly indicate that deformation of the basin fill started during deposition of Upper Langhian to the Upper Tortonian clastics. Shale tectonic deformation was re-activated recently, during the Messinian desiccation of the Mediterranean Sea (and the following catastrophic Pliocene reflooding) or during the Quaternary contourite deposition The sedimentary layers gently dip towards the basin centre and "onlaps" onto the basin margin, especially onto the basement high that bounds the basin toward the East. The contacts observed between the sediment and the basement reflectors are purely stratigraphic. These observations confirm that the geometry is essentially that of a sag basin. We discuss all these stratigraphic observations in the scope of the geodynamic evolution of the eastern and western Alboran basin and the extension recorded onshore during the basin development time interval.

Aquifers of the Denver Basin, Colorado

USGS Publications Warehouse

Topper, R.

2004-01-01

Development of the Denver Basin for water supply has been ongoing since the late 1800s. The Denver Basin aquifer system consists of the water-yielding strata of Tertiary and Cretaceous sedimentary rocks within four overlying formations. The four statutory aquifers contained in these formations are named the Dawson, Denver, Arapahoe, and Laramie-Fox Hills. For water rights administrative purposes, the outcrop/subcrop of the Laramie-Fox Hills aquifer defines the margins of the Basin. Initial estimates of the total recoverable groundwater reserves in storage, under this 6700-mi2 area, were 295 million acre-ft. Recent geologic evidence indicates that the aquifers are very heterogeneous and their composition varies significantly with distance from the source area of the sediments. As a result, available recoverable reserves may be one-third less than previously estimated. There is no legal protection for pressure levels in the aquifer, and water managers are becoming increasingly concerned about the rapid water level declines (30 ft/yr). Approximately 33,700 wells of record have been completed in the sedimentary rock aquifers of the Denver Basin for municipal, industrial, agricultural, and domestic uses.

Compaction of basin sediments as a function of time-temperature history

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmoker, J.W.; Gautier, D.L.

1989-03-01

Processes that affect burial diagenesis are dependent on time-temperature history (thermal maturity). Therefore, the porosity loss of sedimentary rocks during burial may often be better treated as a function of time-temperature history than of depth. Loss of porosity in the subsurface for sandstones, carbonates, and shales can be represented by a power function /phi/ = A(M)/sup B/, where /phi/ is porosity, A and B are constants for a given sedimentary rock population of homogeneous properties, and M is a measure of thermal maturity such as vitrinite reflectance (R/sub 0/) or Lopatin's time-temperature index (TTI). Regression lines of carbonate porosity andmore » of sandstone porosity upon thermal maturity form an envelope whose axis is approximated by /phi/ = 7.5(R/sub 0/)/sup /minus/1.18/ or, equivalently, by /phi/ = 30(TTI)/sup /minus/0.33/. These equations are preliminary generic relations of use for the regional modeling of both carbonate and sandstone compaction in sedimentary basins. The dependence of porosity upon time-temperature history incorporates the hypothesis that porosity-reducing processes operate continuously in sedimentary basins and, consequently, that compaction of basin sediments continues as long as porosity exists. Calculations indicate that subsidence due to loss of porosity through time (with depth held constant) can produce a second-stage passively formed basin in which many hundreds of meters of sediments can accumulate and which conforms with the structure of the original underlying basin. Such sediment accumulation results from the thermal maturation of thick sequences of sedimentary rocks rather than from global sea level change or tectonic subsidence.« less

Geology and evolution of the Northern Kara Sea Shelf

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradov, A.

1991-08-01

The interpretation of regional multichannel seismic reflection profiles collected during 1988-1987 yields the following features of the geology of the Northern Kara Sea Shelf (NKSS). Two regional deep sedimentary basins are clearly distinguished within the NKSS. They have rather complex inner structures and contain sediments 14.0-16.0 km thick. The basin are separated from each other by a relatively narrow, linear zone of basement high which extends from Uedineniya Island on the south to Vize Island on the north, where basement depth is 1.5-4.0 km. The sedimentary sections of the basins are composed of four lithological-stratigraphical sequences separated by unconformities whichmore » correlate well with regional unconformities in adjacent land areas. The initial stages of sedimentary basin development within the NKSS date back to the late Riphean-Vendian; probably they were associated with intracontinental rifting, when up to 4 km of sediments were deposited. During the most of the Phanerozoic, regional subsidence dominated; however, the rates of subsidence were different in the western and in the eastern basins, and varied in time for each basin. The subsidence was interrupted for relatively short periods when the region was affected by uplifts and erosion which resulted in formation of regional unconformities. The seismic data gave no evidence of Caledonian or any other Phanerozoic folding within the NKSS, which is in contrast with widespread assumptions. The results show that the geological structure and evolution of the NKSS differ greatly from those of adjacent Barents and Southern Kara Sea shelves.« less

Neotectonic reactivation of shear zones and implications for faulting style and geometry in the continental margin of NE Brazil

NASA Astrophysics Data System (ADS)

Bezerra, F. H. R.; Rossetti, D. F.; Oliveira, R. G.; Medeiros, W. E.; Neves, B. B. Brito; Balsamo, F.; Nogueira, F. C. C.; Dantas, E. L.; Andrades Filho, C.; Góes, A. M.

2014-02-01

The eastern continental margin of South America comprises a series of rift basins developed during the breakup of Pangea in the Jurassic-Cretaceous. We integrated high resolution aeromagnetic, structural and stratigraphic data in order to evaluate the role of reactivation of ductile, Neoproterozoic shear zones in the deposition and deformation of post-rift sedimentary deposits in one of these basins, the Paraíba Basin in northeastern Brazil. This basin corresponds to the last part of the South American continent to be separated from Africa during the Pangea breakup. Sediment deposition in this basin occurred in the Albian-Maastrichtian, Eocene-Miocene, and in the late Quaternary. However, our investigation concentrates on the Miocene-Quaternary, which we consider the neotectonic period because it encompasses the last stress field. This consisted of an E-W-oriented compression and a N-S-oriented extension. The basement of the basin forms a slightly seaward-tilted ramp capped by a late Cretaceous to Quaternary sedimentary cover ~ 100-400 m thick. Aeromagnetic lineaments mark the major steeply-dipping, ductile E-W- to NE-striking shear zones in this basement. The ductile shear zones mainly reactivated as strike-slip, normal and oblique-slip faults, resulting in a series of Miocene-Quaternary depocenters controlled by NE-, E-W-, and a few NW-striking faults. Faulting produced subsidence and uplift that are largely responsible for the present-day morphology of the valleys and tablelands in this margin. We conclude that Precambrian shear zone reactivation controlled geometry and orientation, as well as deformation of sedimentary deposits, until the Neogene-Quaternary.

Quantifying Channelized Submarine Depositional Systems From Bed to Basin Scale

DTIC Science & Technology

2004-09-01

Union of South Africa and South West Africa . Memoirs of the Geological Survey of South Africa , 39:177, 1944. C.D. Winker and J.R. Booth. Sedimentary ...overbank locations. Sedimentary structures, textures and facies preserved in core recovered from the Late Pliocene section of Fisk Basin are consistent...France or Tanqua, Karoo Basin, South Africa in Pickering et al. (1995)) falling well short of the desirable continuous regional exposure. As a result of

Lithostratigraphie, sédimentologie et évolution de deux bassins molassiques intramontagneux de la chaine Pan-Africaine: la Série pourprée de l'Ahnet, Nord-Ouest du Hoggar, Algérie

NASA Astrophysics Data System (ADS)

Ait-Kaci Ahmed, Ali; Moussine-Pouchkine, Alexis

The study of two of the intermontane molassic basins of the 'Série pourprée de l'Ahnet' shows that they developed independently both in time and space. The characteristics of their thick sedimentary infillings are quite different. The Ouallen basin is filled by essentially fine-grained sediments which were deposited in continental then marine or lacustrine environments; these sediments thicen from east to west. The In Semmen basin is characterised by coarser sediments which were deposited from south to north, in alluvial fan, fluvial, deltaic and slope environments. This basin is also characterised by an episode of carbonate sedimentation leading to the formation of a remarkable thin layer of carbonate, covering the entire sedimentary area, and perhaps related to a volcanic rhyolitic event. The history of the two basins is also marked by obvious tectonic events simultaneous with the sedimentation and related to the recurrent faulting of major Pan-African faults. These led to the formation of very coarse fanglomerates located near the fault scarps, and are probably responsible for the shape and the evolution of the basins.

Tectono-sedimentary evolution of the Neuquén basin (Argentina) between 39°S and 41°S during the Neogene

NASA Astrophysics Data System (ADS)

Huyghe, D.; Bonnel, C.; Nivière, B.; Messager, G.; Dhont, D.; Fasentieux, B.; Hervouët, Y.; Xavier, J.-P.

2012-04-01

Sedimentary rocks deposited in foreland basins are of primary interest, because they record the interactions between the growth of the orogenic wedge, the isostatic readjustment of the lithosphere, the variations of base-level and earth surface process. The Neuquén basin (32°S - 41°S) is a triangular shape foreland basin located on the eastern flank of the Andes. Its filling began during the late Triassic, first as back arc basin context and as compressive foreland basin since the upper Cretaceous. The structural inheritance is thus important and old basement structures, like the Huincul Ridge, generate significant variations of both deformation and shortening. Its Mesozoic history is well constrained due to its hydrocarbon potential. In comparison, its Cenozoic history remains poorly documented. The modern configuration of this basin results from several successive compressive tectonic phases. The last one is dated from the Miocene (Quechua phase) and has conditioned the segmentation of the foreland basin in several intra-mountainous sub-basins, whose sedimentary filling could reach several hundred meters. In this work, we document the relative chronology of the geological events and the sedimentary processes that have governed the Cenozoic history of the southern part of the Neuquen basin, to discriminate the relative rules of climatic and structural controlling factors on the evolution of the depocentres. Several NNW-SSE oriented intra-mountainous basins exist in this part of the Andes (Collon Cura basin and Catan Lil basin). On the contrary the associated foreland basin (Picun Leufu basin) is relatively underformed and is bounded to the North by the Huincul ridge and the North Patagonian massif to the South. Fifteen sedimentary sections have been studied along the Rio Limay River in the southern border of the basin, from the range to the external part of the foreland. The sedimentation is discontinuous in time and important retrogradations of the depocentres are observed from the outer part of the foreland to the intra-mountainous basins. Tertiary sedimentation begins at the end of the Oligocene until the end of the middle Miocene in the Picun Leufu basin. During the paroxysm of the Quechua tectonic phase, (middle Miocene to Pliocene) the Picun Leufu basin is characterised by a sedimentary hiatus of ~10 Ma that illustrates the closure of the Collon Cura basin and a migration to the internal zone of the range of the depocentres. The filling of the Collon Cura basin is characterised by a continental fining upward sequence of a thickness of several hundred meters. This sedimentation begins with lacustrine and alluvial plain paleoenvironments with some syn-eruptive events (ignimbrites) and ends with continental conglomerates and paleosoils. A first reconnexion with the foreland basin occurs at the beginning of the Pliocene, with the deposition of an alluvial fan. Since the end of the Pliocene another anticline grew in the Picun Leufu basin and controlled the deposition of more recent alluvial fans with the arrival of coarse conglomerates (Pampa Curaco and Bayo Messa Formations). The modern drainage network is established during the Pleistocene in the Collon Cura and Picun Leufu basins, which are since only characterised by the construction of erosional surfaces (terraces) and the apparition of the Rio Limay system on the Miocene and Cretaceous deposits.

The interplay of fractures and sedimentary architecture: Natural gas from reservoirs in the Molina sandstones, Piceance Basin, Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenz, J.C.

1997-03-01

The Molina Member of the Wasatch Formation produces natural gas from several fields along the Colorado River in the Piceance Basin, northwestern Colorado. The Molina Member is a distinctive sandstone that was deposited in a unique fluvial environment of shallow-water floods. This is recorded by the dominance of plane-parallel bedding in many of the sandstones. The Molina sandstones crop out on the western edge of the basin, and have been projected into the subsurface and across the basin to correlate with thinner sandy units of the Wasatch Formation at the eastern side of the basin. Detailed study, however, has shownmore » that the sedimentary characteristics of the type-section Molina sandstones are incompatible with a model in which the eastern sandstones are its distal facies equivalent. Rather, the eastern sandstones represent separate and unrelated sedimentary systems that prograded into the basin from nearby source-area highlands. Therefore, only the subsurface {open_quotes}Molina{close_quotes} reservoirs that are in close proximity to the western edge of the basin are continuous with the type-section sandstones. Reservoirs in the Grand Valley and Rulison gas fields were deposited in separate fluvial systems. These sandstones contain more typical fluvial sedimentary structures such as crossbeds and lateral accretion surfaces. Natural fractures play an important role in enhancing the conductivity and permeability of the Molina and related sandstones of the Wasatch Formation.« less

Timing of porosity destruction related to pressure-solution in limestones

NASA Astrophysics Data System (ADS)

Beaudoin, Nicolas; Koehn, Daniel; Aharonov, Einat; Boyce, Adrian; Billi, Andrea; Hamilton, Andrea

2017-04-01

Among effects that affect sedimentary rocks during diagenesis, pressure-solution has a very strong impact on the physical properties of rocks such as porosity and permeability. Intergranular pressure-solution results in rough or wavy surfaces called stylolites, which are very common in sedimentary basins, especially in limestone. According to the opening of the system, dissolved material can precipitate locally, leading to the destruction of the porosity around the stylolite. That can namely occur during the development of sedimentary stylolites, when no fracture of fault can allow dissolved material to flow away before precipitating again. This contribution aims at unravelling the depth at which the material dissolved during compaction precipitated in the open porosity, adding new data to discuss when pressure-solution starts to be an efficient mechanism of deformation in limestone during strata burial in sedimentary basins. We report the results of the study of cements that fill the fractures developed at the tips of stylolites in a sample of dolostone from the Jurassic Calcare Massiccio formation, coming from the Umbria-Marche area (Italy). The fractures developed from stylolite-induced stress, and the filling cements' oxygen and carbon isotopic values range between 10.6‰ to -6.1‰ PDB and -8.2‰ to -0.6‰ PDB, respectively. Considering a closed system, we use fractionation equations to convert δ18O values into temperature, which shows that the material put in solution during pressure-solution precipitated at a temperature ranging from 18°C to 39°C. Temperature range and geothermal gradient estimates suggest that the mechanism of pressure-solution actually was primarily active at depth as low as 1 km. In the studied sample, up to 18% of the original volume has been dissolved on stylolites, and that volume loss would have occurred in the first 2 km of the burial history. This natural example feeds the growing body of evidence that stylolites can start developing at a very low depth level. Our results suggest that the porosity in sedimentary rocks can be destroyed very early during burial, both by dissolution and by precipitation, which make the pressure-solution mechanism's impact on fluid flow in basin likely to be underestimated.

Magnetotelluric and aeromagnetic investigations for assessment of groundwater resources in Parnaiba basin in Piaui State of North-East Brazil

NASA Astrophysics Data System (ADS)

Chandrasekhar, E.; Fontes, Sergio L.; Flexor, Jean M.; Rajaram, Mita; Anand, S. P.

2009-06-01

In an attempt to locate the presence of possible groundwater resource regions in the semi-arid North-East Brazil, an integrated survey including aeromagnetic and magnetotelluric (MT) studies have been undertaken in the Guaribas region and only MT survey in the Caracol region. In the Guaribas region the aeromagnetic data, its analytic signal and Euler solutions reveal several subsurface small-scale faults and intrusives that are conducive to be potential groundwater resource regions. A total of about 22 broad-band magnetotelluric (MT) soundings in the period range of 0.006-300 s along two profiles on the marginal arcs of the intra-cratonic sedimentary Parnaíba basin in North-East Brazil have been made across the regional geological strike, the Senador Pompeu Lineament (SPL). SPL trends N40°E and marks a basement high reflecting an irregularity in the original basin geometry. While one of the MT profiles traverses across the SPL, the other lies only in the aeromagnetically surveyed sedimentary region. Two-dimensional inversion of MT data of both profiles shows that the sedimentary basin is conductive (100-150 Ω m) and shows as a thin graben with an average thickness of about 2-3 km beneath both profiles. The basin is located to be at shallow depths (from surface to about 500 m). Based on the facts that the study region falls on sedimentary region having low-to-very low permeability and also in accordance with the subsurface lithology around the study region, the mapped sedimentary basin largely manifests the zone of potential sedimentary aquifer having moderate resistivity of 50-250 Ω m and is located at relatively shallow depths. The identified aquifer zone is believed to have links with the Parnaiba River flowing at a distance of about 300 km NW from the study region. We discuss interpretation of our results of MT and aeromagnetic data sets in the light of hydrological features of the study region.

Tectonic evolution of the Anadyr Basin, northeastern Eurasia, and its petroleum resource potential

NASA Astrophysics Data System (ADS)

Antipov, M. P.; Bondarenko, G. E.; Bordovskaya, T. O.; Shipilov, E. V.

2009-09-01

The published data on the sedimentation conditions, structure, and tectonic evolution of the Anadyr Basin in the Mesozoic and Cenozoic are reviewed. These data are re-examined in the context of modern tectonic concepts concerning the evolution of the northwestern Circum-Pacific Belt. The re-examination allows us not only to specify the regional geology and tectonic history, but also to forecast of the petroleum resource potential of the sedimentary cover based on a new concept. The sedimentary cover formation in the Anadyr Basin is inseparably linked with the regional tectonic evolution. The considered portion of the Chukchi Peninsula developed in the Late Mesozoic at the junction of the ocean-type South Anyui Basin, the Asian continental margin, and convergent zones of various ages extending along the Asia-Pacific interface. Strike-slip faulting and pulses of extension dominated in the Cenozoic largely in connection with oroclinal bending of structural elements pertaining to northeastern Eurasia and northwestern North America against the background of accretion of terranes along the zone of convergence with the Pacific oceanic plates. Three main stages are recognized in the formation of the sedimentary cover in the Anadyr Basin. (1) The lower portion of the cover was formed in the Late Cretaceous-Early Eocene under conditions of alternating settings of passive and active continental margins. The Cenomanian-lower Eocene transitional sedimentary complex is located largely in the southern Anadyr Basin (Main River and Lagoonal troughs). (2) In the middle Eocene and Oligocene, sedimentation proceeded against the background of extension and rifting in the northern part of the paleobasin and compression in its southern part. The compression was caused by northward migration of the foredeep in front of the accretionary Koryak Orogen. The maximum thickness of the Eocene-Oligocene sedimentary complex is noted mainly in the southern part of the basin and in the Central and East Anadyr troughs. (3) The middle Miocene resumption of sedimentation was largely related to strike-slip faulting and rifting. In the Miocene to Quaternary, sedimentation was the most intense in the central and northern parts of the Anadyr Basin, as well as in local strike-slip fault-line depressions of the Central Trough. Geological and geophysical data corroborate thrusting in the southern Anadyr Basin. The amplitude of thrusting over the Main River Trough reaches a few tens of kilometers. The vertical thickness of the tectonically screened Paleogene and Neogene rocks in the southern Main River Trough exceeds 10 km. The quantitative forecast of hydrocarbon emigration from Cretaceous and Paleogene source rocks testifies to the disbalance between hydrocarbons emigrated and accumulated in traps of petroleum fields discovered in the Anadyr Basin. The southern portion of the Anadyr Basin is the most promising for the discovery of new petroleum fields in the Upper Cretaceous, Eocene, and Upper Oligocene-Miocene porous and fracture-porous reservoir rocks in subthrust structural and lithological traps.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narr, W.; Currie, J.B.

The occurrence of natural fracture systems in subsurface rock can be predicted if careful evaluation is made of the ecologic processes that affect sedimentary strata during their cycle of burial, diagenesis, uplift, and erosional unloading. Variations in the state of stress within rock arise, for example, from changes in temperature, pore pressure, weight of overburden, or tectonic loading. Hence geologic processes acting on a sedimentary unit should be analyzed for their several contributions to the state of stress, and this information used to compute a stress history. From this stress history, predictions may be made as to when in themore » burial cycle to expect fracture (joint) formation, what type of fractures (extension or shear) may occur, and which geologic factors are most favorable to development of fractures. A stress history is computed for strata of the naturally fractured Altamont oil field in Utah's Uinta basin. Calculations suggest that fractures formed in extension, that the well-cemented rocks are those most likely to be fractured, that fractures began to develop only after stata were uplifted and denuded of overburden. Geologic evidence on fracture genesis and development is in accord with the stress history prediction. Stress history can be useful in evaluating a sedimentary basin for naturally fractured reservoir exploration plays.« less

Permo-Carboniferous sedimentary basins related to the distribution of planetary cryptoblemes

USGS Publications Warehouse

Windolph, J.F.

1997-01-01

Massive/high velocity solar, galactic, and cosmic debris impacting the Earths surface may account for the enormous energy required for the formation of Permo-Carboniferous sedimentary basins and related mountain building orogenies. Analysis of satellite immagry, sea floor sonar, geophysical data, and geotectonic fabrics show a strong correlation throughout geologic time between sedimentary basin origin and planetary cryptoblemes. Cryptoblemes are subtile, multi-ringed, radial centric impact shock signatures covering the entire terrestrial surface and ocean floors, having a geometry and distribution strikingly similar to the surfaces of the lunar planetary bodies in the solar system. Investigations of Permo-Carboniferous basins show an intensely overprinted pattern of cryptoblemes coinciding with partial obliteration and elliptical compression of pre-existing basins and accompanying shock patterns. Large distorted cryptoblemes may incorporate thin skin deformation, localized sediment diagenesis, regional metamorphism, and juxtaposed exotic terrains. These data, related to basin morphogenic symmetry, suggest that large episodic impact events are the primary cause of tectonogenic features, geologic boundary formation and mass extinction episodes on the planet Earth. Plate tectonics may be only a slow moving, low energy secondary effect defined and set in motion by megacosmic accretion events. Permo-Carboniferous sediments of note are preserved or accumulated in relatively small rectangular to arcuate rift valleys and synclinal down warps, such as the Narraganset basin of Massachusetts, USA, and Paganzo basin in Argentina, S.A. These deposits and depocenters may originate from dynamic reinforcement/cancellation impact effects, as can be seen in the Basin Range of Nevada and Utah, USA. Large circular to oval sedimentary basins commonly include internal ring structures indicating post depositional subsidence and rebound adjustments with growth faulting, notable in the Illinois basin USA and Ordos basin in China. Recent impact events on the planet Jupiter, July 1994, lend increasing support towards an impact orogenic geologic paradigm on the planet Earth.

Summary of the geology and resources of uranium in the San Juan Basin and adjacent region, New Mexico, Arizona, Utah, and Colorado

USGS Publications Warehouse

Ridgley, Jennie L.; Green, M.W.; Pierson, C.T.; Finch, W.I.; Lupe, R.D.

1978-01-01

The San Juan Basin and adjacent region lie predominantly in the southeastern part of the uranium-rich Colorado Plateau of New Mexico, Arizona, Utah, and Colorado. Underlying the province are rocks of the Precambrian basement complex composed mainly of igneous and metamorphic rocks; a thickness of about 3,600 meters of generally horizontal Paleozoic, Mesozoic, and Cenozoic sedimentary rocks; and a variety of Upper Cretaceous and Cenozoic igneous rocks. Sedimentary rocks of the sequence are commonly eroded and well exposed near the present basin margins where Tertiary tectonic activity has uplifted, folded, and faulted the sequence into its present geologic configuration of basins, platforms, monoclines, and other related structural features. Sedimentary rocks of Jurassic age in the southern part of the San Juan Basin contain the largest uranium deposits in the United States, and offer the promise of additional uranium deposits. Elsewhere in the basin and the adjacent Colorado Plateau, reserves and resources of uranium are known primarily in Triassic, Jurassic, and Cretaceous strata. Only scattered occurrences of uranium are known in Paleozoic

A refined model of sedimentary rock cover in the southeastern part of the Congo basin from GOCE gravity and vertical gravity gradient observations

NASA Astrophysics Data System (ADS)

Martinec, Zdeněk; Fullea, Javier

2015-03-01

We aim to interpret the vertical gravity and vertical gravity gradient of the GOCE-GRACE combined gravity model over the southeastern part of the Congo basin to refine the published model of sedimentary rock cover. We use the GOCO03S gravity model and evaluate its spherical harmonic representation at or near the Earth's surface. In this case, the gradiometry signals are enhanced as compared to the original measured GOCE gradients at satellite height and better emphasize the spatial pattern of sedimentary geology. To avoid aliasing, the omission error of the modelled gravity induced by the sedimentary rocks is adjusted to that of the GOCO03S gravity model. The mass-density Green's functions derived for the a priori structure of the sediments show a slightly greater sensitivity to the GOCO03S vertical gravity gradient than to the vertical gravity. Hence, the refinement of the sedimentary model is carried out for the vertical gravity gradient over the basin, such that a few anomalous values of the GOCO03S-derived vertical gravity gradient are adjusted by refining the model. We apply the 5-parameter Helmert's transformation, defined by 2 translations, 1 rotation and 2 scale parameters that are searched for by the steepest descent method. The refined sedimentary model is only slightly changed with respect to the original map, but it significantly improves the fit of the vertical gravity and vertical gravity gradient over the basin. However, there are still spatial features in the gravity and gradiometric data that remain unfitted by the refined model. These may be due to lateral density variation that is not contained in the model, a density contrast at the Moho discontinuity, lithospheric density stratifications or mantle convection. In a second step, the refined sedimentary model is used to find the vertical density stratification of sedimentary rocks. Although the gravity data can be interpreted by a constant sedimentary density, such a model does not correspond to the gravitational compaction of sedimentary rocks. Therefore, the density model is extended by including a linear increase in density with depth. Subsequent L2 and L∞ norm minimization procedures are applied to find the density parameters by adjusting both the vertical gravity and the vertical gravity gradient. We found that including the vertical gravity gradient in the interpretation of the GOCO03S-derived data reduces the non-uniqueness of the inverse gradiometric problem for density determination. The density structure of the sedimentary formations that provide the optimum predictions of the GOCO03S-derived gravity and vertical gradient of gravity consists of a surface density contrast with respect to surrounding rocks of 0.24-0.28 g/cm3 and its decrease with depth of 0.05-0.25 g/cm3 per 10 km. Moreover, the case where the sedimentary rocks are gravitationally completely compacted in the deepest parts of the basin is supported by L∞ norm minimization. However, this minimization also allows a remaining density contrast at the deepest parts of the sedimentary basin of about 0.1 g/cm3.

Compaction and sedimentary basin analysis on Mars

NASA Astrophysics Data System (ADS)

Gabasova, Leila R.; Kite, Edwin S.

2018-03-01

Many of the sedimentary basins of Mars show patterns of faults and off-horizontal layers that, if correctly understood, could serve as a key to basin history. Sediment compaction is a possible cause of these patterns. We quantified the possible role of differential sediment compaction for two Martian sedimentary basins: the sediment fill of Gunjur crater (which shows concentric graben), and the sediment fill of Gale crater (which shows outward-dipping layers). We assume that basement topography for these craters is similar to the present-day topography of complex craters that lack sediment infill. For Gunjur, we find that differential compaction produces maximum strains consistent with the locations of observed graben. For Gale, we were able to approximately reproduce the observed layer orientations measured from orbiter image-based digital terrain models, but only with a >3 km-thick donut-shaped past overburden. It is not immediately obvious what geologic processes could produce this shape.

HVDC Ground Electrodes and Tectonic Setting

NASA Astrophysics Data System (ADS)

Freire, P. F.; Pereira, S. Y.

2017-12-01

Ground electrodes in HVDC transmission are huge grounding systems for the DC part of the converter substation, about 1 km wide, sized to inject in the ground DC currents up to 3.5 kA. This work presents an analysis of how the tectonic setting at converter substation location is determinant for the search of the best electrode location (Site Selection) and on its design and performance. It will briefly present the author experience on HVDC electrode design, summarized as follows: Itaipu - Foz do Iguaçu electrodes (transmitter side) located in the middle of Paraná Sedimentary Basin, and Ibiúna electrodes (receiving side) on the border of the basin, 6 km from the geological strike, where the crystalline basement outcrops in São Paulo state; Madeira River - North electrodes (transmitting side) located on the Northwest border of South Amazon Craton, where the crystalline basement is below a shallow sediments layer, and South electrodes (receiving side) located within Paraná Sedimentary Basin; Chile - electrodes located on the Andean forearc, where the Nazca Plate plunges under the South American Plate; Kenya - Ethiopia - electrodes located in the African Rift; Belo Monte - North electrodes (transmitter side) located within the Amazonian Sedimentary Basin, about 35 km of its South border, and South electrodes (receiving side) within Paraná Sedimentary Basin (bipole 1) and on crystalline metamorphic terrain "Brasília Belt" (bipole 2). This diversity of geological conditions results on ground electrodes of different topologies and dimensions, with quite different electrical and thermal performances. A brief study of the geology of the converter stations regions, the so-called Desktop Study, allows for the preview of several important parameters for the site selection and design of the electrodes, such as localization, type, size and estimate of the interference area, which are important predictors of the investment to be made and indications of the design to be developed.

Provenance and accommodation pathways of late Quaternary sediments in the deep-water northern Ionian Basin, southern Italy

NASA Astrophysics Data System (ADS)

Perri, Francesco; Critelli, Salvatore; Dominici, Rocco; Muto, Francesco; Tripodi, Vincenzo; Ceramicola, Silvia

2012-12-01

The northern Calabria along the southeastern coast of Italy provides a favorable setting in which to study complete transects from continental to deep-marine environments. The present northern Ionian Calabrian Basin is a wedge-top basin within the modern foreland-basin system of southern Italy. The Ionian margin of northern Calabria consists of a moderately developed fluvial systems, the Crati and Neto rivers, and diverse smaller coastal drainages draining both the Calabria continental block (i.e., Sila Massif) and the southern Apennines thrust belt (i.e., Pollino Massif). The main-channel sand of the Crati and Neto rivers is quartzofeldspathic with abundant metamorphic and plutonic lithic fragments (granodiorite, granite, gneiss, phyllite and sedimentary lithic fragments). Sedimentary lithic fragments were derived from Jurassic sedimentary successions of the Longobucco Group. The mud samples contain mostly phyllosilicates, quartz, calcite, feldspars and dolomite. Traces of gypsum are present in some samples. The I-S mixed layers, 10 Å-minerals (illite and micas), chlorite and kaolinite are the most abundant phyllosilicates, whereas smectite and chlorite/smectite mixed layers are in small amounts. The geochemical signatures of the muds reflect a provenance characterized by both felsic and mafic rocks with a significant input from carbonate rocks. Furthermore, the degree of source-area weathering was most probably of low intensity rather than moderately intense because CIA values for the studied mud samples are low. Extrapolation of the mean erosion budget from 1 to 25 Ma suggests that at least 5 to 8 km of crust have been removed from the Calabrian orogenic belt and deposited in the marine basins. The Calabrian microplate played an important role in the dynamic evolution of southern Italian fossil and modern basins, representing the key tectonic element of the entire orogenic belt.

Nature and tectonic implications of uneven sedimentary filling of the South China Sea oceanic basin

NASA Astrophysics Data System (ADS)

Yin, Shaoru; Li, Jiabiao; Ding, Weiwei; Fang, Yinxia

2017-04-01

The IODP Expedition 349 in 2014, for the first time, illustrated significant differences of sediment rate and lithology in the central South China Sea (SCS) oceanic basin. Based on seismic reflection profiles tied to IODP349 drilling data, we investigated characteristics of sedimentary filling of the whole SCS oceanic basin, and examined their implications for tectonics. Results show that sediments fill the SCS oceanic basin mainly in three depositional patterns. Firstly, during the Oligocene to middle Miocene, sediments amassed almost solely and then connected like a band parallel to the continent in a low average sediment rate (<10 m/Myr) in the northern oceanic basin. These sediments were deposited mainly in the form of submarine fans and mass transport deposits. Sediments were predominately supplied by the Red and Pearl Rivers and the Dongsha Islands. The sedimentary characteristics likely reflect the latest early Miocene end of seafloor spreading of the SCS and the first-phase rapid uplift of the Tibetan Plateau. Secondly, during the late Miocene, deposition mainly occurred in the Northwest Sub-basin and extended southeastward with a middle average sediment rate ( 30 m/Myr). Sediments were mostly transported by the Red River and Xisha Trough and deposited in the form of submarine fans. The abnormal increase of sediment rate in the Northwest Sub-basin reflects late Miocene slip reversal of the Red River Fault. Finally, since the Pliocene, sediments gradually propagated northeastward in the Southwestern Sub-basin, and accumulated rapidly in the southeastern and northeastern basin, especially in the northern Manila Trench during the Quaternary, in an average sediment rate about 60-80 m/Myr. These sediments were transported mainly by submarine canyons and settled in the form of submarine fans and canyon-overbank deposition. Sediments came from four major sources, including Taiwan, Dongsha Islands, Mekong River, and northern Palawan. The Pliocene to Quaternary explosion of uneven sedimentary filling in the SCS oceanic basin points to the combined action of local and regional tectonics, including the two-phase rapid uplift of the Tibetan Plateau, the Pliocene to Quaternary increased northwestward movement of the Philippine Sea plate and Dongsha event. This study exhibits hitherto most completed observation of sedimentary filling of the SCS oceanic basin and provides new geophysical evidences for the local and regional important tectonics.

Seismic responses and controlling factors of Miocene deepwater gravity-flow deposits in Block A, Lower Congo Basin

NASA Astrophysics Data System (ADS)

Wang, Linlin; Wang, Zhenqi; Yu, Shui; Ngia, Ngong Roger

2016-08-01

The Miocene deepwater gravity-flow sedimentary system in Block A of the southwestern part of the Lower Congo Basin was identified and interpreted using high-resolution 3-D seismic, drilling and logging data to reveal development characteristics and main controlling factors. Five types of deepwater gravity-flow sedimentary units have been identified in the Miocene section of Block A, including mass transport, deepwater channel, levee, abandoned channel and sedimentary lobe deposits. Each type of sedimentary unit has distinct external features, internal structures and lateral characteristics in seismic profiles. Mass transport deposits (MTDs) in particular correspond to chaotic low-amplitude reflections in contact with mutants on both sides. The cross section of deepwater channel deposits in the seismic profile is in U- or V-shape. The channel deposits change in ascending order from low-amplitude, poor-continuity, chaotic filling reflections at the bottom, to high-amplitude, moderate to poor continuity, chaotic or sub-parallel reflections in the middle section and to moderate-weak amplitude, good continuity, parallel or sub-parallel reflections in the upper section. The sedimentary lobes are laterally lobate, which corresponds to high-amplitude, good-continuity, moundy reflection signatures in the seismic profile. Due to sediment flux, faults, and inherited terrain, few mass transport deposits occur in the northeastern part of the study area. The front of MTDs is mainly composed of channel-levee complex deposits, while abandoned-channel and lobe-deposits are usually developed in high-curvature channel sections and the channel terminals, respectively. The distribution of deepwater channel, levee, abandoned channel and sedimentary lobe deposits is predominantly controlled by relative sea level fluctuations and to a lesser extent by tectonism and inherited terrain.

On the Application of an Enthalpy Method to the Evolution of Fluvial Deltas Under Sea-Level Changes

NASA Astrophysics Data System (ADS)

Anderson, W.; Lorenzo-Trueba, J.; Voller, V. R.

2017-12-01

Fluvial deltas are composites of two primary sedimentary environments: a depositional fluvial region and an offshore region. The fluvial region is defined by two geomorphic moving boundaries: an alluvial-bedrock transition (ABT), which separates the sediment prism from the non-erodible bedrock basement, and the shoreline (SH), where the delta meets the ocean. The trajectories of these boundaries in time and space define the evolution of the shape of the sedimentary prism, and are often used as stratigraphic indicators, particularly in seismic studies, of changes in relative sea level and the identification of stratigraphic sequences. In order to better understand the relative role of sea-level variations, tectonics, and sediment supply on the evolution of these boundaries, we develop a forward stratigraphic model that captures the dynamic behavior of the fluvial surface and treats the SH and ABT as moving boundaries (i.e., internal boundaries whose location must be determined as part of the solution to the overall morphological evolution problem). This forward model extends a numerical technique from heat transfer (i.e., enthalpy method), previously applied to the evolution of sedimentary basins, to account for sea-level changes. The mathematics of the approach are verified by comparing predictions from the numerical model with both existing and newly developed closed form analytical solutions. Model results support previous work, which suggests that the migration of the ABT can respond very differently to the sea-level signal. This response depends on factors such as sediment supply and delta length, which can vary greatly between basins. These results can have important implications for the reconstruction of past sea-level changes from the stratigraphic record of sedimentary basins.

Aeromagnetic anomalies over faulted strata

USGS Publications Warehouse

Grauch, V.J.S.; Hudson, Mark R.

2011-01-01

High-resolution aeromagnetic surveys are now an industry standard and they commonly detect anomalies that are attributed to faults within sedimentary basins. However, detailed studies identifying geologic sources of magnetic anomalies in sedimentary environments are rare in the literature. Opportunities to study these sources have come from well-exposed sedimentary basins of the Rio Grande rift in New Mexico and Colorado. High-resolution aeromagnetic data from these areas reveal numerous, curvilinear, low-amplitude (2–15 nT at 100-m terrain clearance) anomalies that consistently correspond to intrasedimentary normal faults (Figure 1). Detailed geophysical and rock-property studies provide evidence for the magnetic sources at several exposures of these faults in the central Rio Grande rift (summarized in Grauch and Hudson, 2007, and Hudson et al., 2008). A key result is that the aeromagnetic anomalies arise from the juxtaposition of magnetically differing strata at the faults as opposed to chemical processes acting at the fault zone. The studies also provide (1) guidelines for understanding and estimating the geophysical parameters controlling aeromagnetic anomalies at faulted strata (Grauch and Hudson), and (2) observations on key geologic factors that are favorable for developing similar sedimentary sources of aeromagnetic anomalies elsewhere (Hudson et al.).

Areal distribution of sedimentary facies determined from seismic facies analysis and models of modern depositional systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seramur, K.C.; Powell, R.D.; Carpenter, P.J.

1988-02-01

Seismic facies analysis was applied to 3.5-kHz single-channel analog reflection profiles of the sediment fill within Muir Inlet, Glacier Bay, southeast Alaska. Nine sedimentary facies have been interpreted from seven seismic facies identified on the profiles. The interpretations are based on reflection characteristics and structural features of the seismic facies. The following reflection characteristics and structural features are used: reflector spacing, amplitude and continuity of reflections, internal reflection configurations, attitude of reflection terminations at a facies boundary, body geometry of a facies, and the architectural associations of seismic facies within each basin. The depositional systems are reconstructed by determining themore » paleotopography, bedding patterns, sedimentary facies, and modes of deposition within the basin. Muir Inlet is a recently deglaciated fjord for which successive glacier terminus positions and consequent rates of glacial retreat are known. In this environment the depositional processes and sediment characteristics vary with distance from a glacier terminus, such that during a retreat a record of these variations is preserved in the aggrading sediment fill. Sedimentary facies within the basins of lower Muir Inlet are correlated with observed depositional processes near the present glacier terminus in the upper inlet. The areal distribution of sedimentary facies within the basins is interpreted using the seismic facies architecture and inferences from known sediment characteristics proximal to present glacier termini.« less

Sedimentary Evolution of Marginal Ganga Foreland Basin during the Late Pleistocene

NASA Astrophysics Data System (ADS)

Ghosh, R.; Srivastava, P.; Shukla, U. K.

2017-12-01

Ganga foreland basin, an asymmetrical basin, was formed as result of plate-plate collision during middle Miocene. A major thrust event occurred during 500 ka when upper Siwalik sediments were uplifted and the modern Ganga foreland basin shifted towards craton, making a more wide and deep basin. The more distal part of this basin, south of axial river Yamuna, records fluvial sedimentary packages that helps to understand dynamics of peripheral bulge during the late Quaternary. Sedimentary architecture in conjunction with chemical index of alteration (CIA), paleocurrent direction and optically stimulated dating (OSL) from 19 stratigraphic sections helped reconstructing the variations in depositional environments vis-à-vis climate change and peripheral bulge tectonics. Three major units (i) paleosol; (ii) cratonic gravel; (iii) interfluve succession were identified. The lower unit-I showing CIA values close to 70-80 and micro-morphological features of moderately well-developed pedogenic unit that shows development of calcrete, rhizoliths, and mineralized organic matter in abundance. This is a regional paleosols unit and OSL age bracketed 200 ka. This is unconformably overlain by unit-II, a channelized gravel composed of sub-angular to sub-rounded clasts of granite, quartz, quartzite, limestone and calcrete. The gravel have low CIA value up to 55, rich in vertebrate fossil assemblages and mean paleocurrent vector direction is NE, which suggesting deposition by a fan of a river draining craton into foreland. This unit is dated between 100 ka and 54 ka. The top unit-III, interfluve succession of 10-15 m thick is composed of dark and light bands of sheet like deposit of silty clay to clayey silt comprises sand lenses of red to grey color and displaying top most OSL age is 12 ka. The basal mature paleosol signifies a humid climate developed under low subsidence rate at >100 ka. After a hiatus represented by pedogenic surface deposition of unit-II (gravel) suggests uplift and increased relief in the peripheral bulge region resulting into large flux of coarse sediments from craton. This was accompanied by humid climate and braided rivers forming a craton derived north propagating fans. Similar depositional setup at the base Siwalik is termed as peripheral bulge unconformity.

Genesis of copper-lead mineralization in the regionally zoned Agnigundala Sulfide Belt, Cuddapah Basin, Andhra Pradesh, India

NASA Astrophysics Data System (ADS)

Bhattacharya, H. N.; Bandyopadhyay, Sandip

2018-03-01

Shallow marine sandstone-shale-carbonate sedimentary rocks of the Paleoproterozoic northern Cuddapah basin host copper (Nallakonda deposit), copper-lead (Dhukonda deposit), and lead mineralization (Bandalamottu deposit) which together constitute the Agnigundala Sulfide Belt. The Cu sulfide mineralization in sandstone is both stratabound and disseminated, and Pb sulfide mineralization occurs as stratabound fracture filling veins and/or replacement veins within dolomite. Systematic mineralogical and sulfur, carbon, and oxygen isotope studies of the three deposits indicate a common ore-fluid that deposited copper at Nallakonda, copper-lead at Dhukonda, and lead at Bandalamottu under progressive cooling during migration through sediments. The ore-fluid was of low temperature (< 200 °C) and oxidized. Thermochemical reduction of basinal water sulfate produced sulfide for ore deposition. It is envisaged that basal red-bed and evaporite-bearing rift-related continental to shallow marine sediments might have acted as the source for the metals. Rift-related faults developed during sedimentation in the basin might have punctured the ore-fluid pool in the lower sedimentary succession and also acted as conduits for their upward migration. The ore-bearing horizons have participated in deformations during basin inversion without any recognizable remobilization.

Analysis of petroleum potential of Philippine sedimentary basins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saldivar-Sali, A.; Harrison, J.; Flower, L.

1986-07-01

An extensive reevaluation of the petroleum potential of all sedimentary basins in the Philippine Archipelago was recently completed using World Bank funds. The study was conducted jointly by the technical staff of the Bureau of Energy Development (BED)/Philippine National Oil Company (PNOC) and senior consultants from Robertson Research, and Flower, Doery, Buchan Pty. Ltd., from 1983 to 1986. The joint team spent 2 1/2 years on the study and produced detailed reports and atlases, which constitute the most comprehensive basin analysis and petroleum potential assessment of the 13 major basins in the Philippines. Voluminous data available at the start ofmore » the project were supplemented by a countrywide aeromagnetic survey (216,000 km) and 9200 km of new marine seismic in 15 different areas. These surveys were also funded by the World Bank. The integration of all relevant geoscientific disciplines resulted in a better understanding of the geologic evolution of each basin and its bearing on the generation, migration, and entrapment of hydrocarbons. Many similarities and common characteristics were noted in the evolution and sedimentation of some basins. Play concepts have been developed and proposed for each basin, many of which are new plays that were not the objectives of previous exploration. The degree of exploration in these basins varies, and clearly, exploration activity has not reached a mature stage in any basin. Even where wells are numerous, many of them are old and shallow and of limited geologic value. Elsewhere, particularly offshore, there are large areas where no wells have been drilled. In conclusion, the bilateral cooperation between the Philippine government and the World Bank, particularly when exploration activity in the private sector was at a low level, proved most timely and beneficial.« less

Sources of Minor and Rare-Earth Elements in Hydrothermal Edifices of Near-Continental Rifts with Sedimentary Cover: Evidence from the Guaymas Basin, Southern Trough

NASA Astrophysics Data System (ADS)

Lein, A. Yu.; Dara, O. M.; Bogdanova, O. Yu.; Novikov, G. V.; Ulyanova, N. V.; Lisitsyn, A. P.

2018-03-01

The mineralogy and geochemistry of a fragment of an active hydrothermal edifice from the Hydrothermal Hill of the Southern Trough valley of the Guaymas Basin in the Gulf of California were studied. The sample was collected from a depth of 1995 m by the Pisces manned submersible on cruise 12 of the R/V Akademik Mstislav Keldysh, Institute of Oceanology, Russian Academy of Sciences. The fragment and the edifice itself consists of two accrete pipes: ore (pyrrhotite) and barren (carbonate) combined in a single edifice by an outer barite-opal zone. The ore edifice is located in the rift zone of the Guaymas Basin with a thick sedimentary cover and is depleted in metals in comparison with ores from rift zones of the open ocean, which are not blocked by sedimentary deposits. This is explained by loss of metals at the boundary between hot sills and sedimentary rocks and by the processes of interaction of hydrothermal solutions with sedimentary deposits. The sedimentary series faciitates long-term preservation of endogenous heat and the ore formation process. Ore edifices of the Guaymas Basin are mostly composed of pyrrhotite, have a specific set of major elements, microelements and REEs, and contain naphthenic hydrocarbons. They may be search signs of hidden polymetallic deposits, considered to be the roots of ore occurrences localized under the surface of the bottom in young active rifts with high spreading and sedimentation rates, i.e., in near-continental areas of rifts of the humid zone with avalanche sedimentation.

Low-angle faulting in strike-slip dominated settings: Seismic evidence from the Maritimes Basin, Canada

NASA Astrophysics Data System (ADS)

Pinet, Nicolas; Dietrich, Jim; Duchesne, Mathieu J.; Hinds, Steve J.; Brake, Virginia

2018-07-01

The Maritimes Basin is an upper Paleozoic sedimentary basin centered in the Gulf of St. Lawrence (Canada). Early phases of basin formation included the development of partly connected sub-basins bounded by high-angle faults, in an overall strike-slip setting. Interpretation of reprocessed seismic reflection data indicates that a low-angle detachment contributed to the formation of a highly asymmetric sub-basin. This detachment was rotated toward a lower angle and succeeded by high-angle faults that sole into the detachment or cut it. This model bears similarities to other highly extended terranes and appears to be applicable to strike-slip and/or transtensional settings.

Cenozoic sedimentation in the Mumbai Offshore Basin: Implications for tectonic evolution of the western continental margin of India

NASA Astrophysics Data System (ADS)

Nair, Nisha; Pandey, Dhananjai K.

2018-02-01

Interpretation of multichannel seismic reflection data along the Mumbai Offshore Basin (MOB) revealed the tectonic processes that led to the development of sedimentary basins during Cenozoic evolution. Structural interpretation along three selected MCS profiles from MOB revealed seven major sedimentary sequences (∼3.0 s TWT, thick) and the associated complex fault patterns. These stratigraphic sequences are interpreted to host detritus of syn- to post rift events during rift-drift process. The acoustic basement appeared to be faulted with interspaced intrusive bodies. The sections also depicted the presence of slumping of sediments, subsidence, marginal basins, rollover anticlines, mud diapirs etc accompanied by normal to thrust faults related to recent tectonics. Presence of upthrusts in the slope region marks the locations of local compression during collision. Forward gravity modeling constrained with results from seismic and drill results, revealed that the crustal structure beneath the MOB has undergone an extensional type tectonics intruded with intrusive bodies. Results from the seismo-gravity modeling in association with litholog data from drilled wells from the western continental margin of India (WCMI) are presented here.

Chapter 27: Geology and petroleum potential of the north and east margins of the Siberian Craton, north of the Arctic Circle

USGS Publications Warehouse

Klett, T.R.; Wandrey, C.J.; Pitman, Janet K.

2011-01-01

The Siberian Craton consists of crystalline rocks and superimposed Precambrian sedimentary rocks deposited in rift basins. Palaeozoic rocks, mainly carbonates, were deposited along the margins of the craton to form an outwardly younger concentric pattern that underlies an outward-thickening Mesozoic sedimentary section. The north and east margins of the Siberian Craton subsequently became foreland basins created by compressional deformation during collision with other tectonic plates. The Tunguska Basin developed as a Palaeozoic rift/sag basin over Proterozoic rifts. The geological provinces along the north and east margins of the Siberian Craton are immature with respect to exploration, so exploration-history analysis alone cannot be used for assessing undiscovered petroleum resources. Therefore, other areas from around the world having greater petroleum exploration maturity and similar geological characteristics, and which have been previously assessed, were used as analogues to aid in this assessment. The analogues included those of foreland basins and rift/sag basins that were later subjected to compression. The US Geological Survey estimated the mean undiscovered, technically recoverable conventional petroleum resources to be approximately 28 billion barrels of oil equivalent, including approximately 8 billion barrels of crude oil, 103 trillion cubic feet of natural gas and 3 billion barrels of natural gas liquids. ?? 2011 The Geological Society of London.

Mössbauer spectroscopic study of the test well (DND) located in Jaisalmer Basin of Rajasthan, India

NASA Astrophysics Data System (ADS)

Ganwani, Girish; Meena, Samay Singh; Ram, Sahi; Bhatia, Beena; Tripathi, R. P.

2018-05-01

The Jaisalmer basin represents mainly the westerly dipping flank of Indus shelf. The palynological and geochemical studies have predicted good quality of hydrocarbons in this basin. The cretaceous and Jurassic sediments are believed to contain source rock in this basin. In present preliminary study, Mössbauer spectroscopic investigation has been done on sedimentary samples collected from different depths of upper cretaceous sedimentary sequence of well DND-1 drilled in Jaisalmer basin. The iron is found mainly in carbonate and clay. The relatively small presence of Fe2+ in comparison to Fe3+ in clay is an indication of poor reducing environment in sediments, which can be attributed to poor maturity of source rocks in upper cretaceous sediments of this basin.

Influence of inherited structures on the growth of basement-cored ranges, basin inversion and foreland basin development in the Central Andes, from apatite fission-track and apatite Helium thermochronology.

NASA Astrophysics Data System (ADS)

Zapata, S.; Sobel, E. R.; Del Papa, C.; Jelinek, A. R.; Muruaga, C.

2017-12-01

The Central Andes in NW of Argentina is part of a long-lived subduction zone, active since the Paleozoic. This region experienced several tectonic cycles; each of which created an unique set of structures and may have reactivated preexisting structures. These inherited structures may exert a first-order control over the different foreland deformational styles observed along the strike in the Central Andes. Our study area is located between 26°S and 28°S on the transition between the broken foreland (Santa Barbara system), which expresses a combination of thin-skin and thick-skin styles, and the Sierras Pampeanas, which is deform in a thick-skin style. The Cumbres Calchaquies range and the associated Choromoro Basin are located in the northern part of the study area, and are the southern expression of the Santa Barbara system. Published thermochronology data suggest that the rocks from the basement experienced Late Cretaceous and Late Miocene exhumation; the associated sedimentary rocks within the Choromoro basin experienced Paleogene and Late Miocene deformational phases. In contrast, the Sierra Aconquija range, located immediately south on the transition to the Sierras Pampeanas (thick skin) foreland basin, exhibit larger amounts of Miocene exhumation and lack of Cretaceous exhumation; the associated sedimentary rocks from the Tucuman basin have not been deformed since the Cretaceous. Our goal is to understand the evolution of the structural blocks and the structures responsible for the along strike changes in foreland basin deformational styles and their relation with inherited structures from previous tectonic cycles. We are obtaining new apatite U-Th/He and fission track data to reconstruct the thermal history of the basement, accompanied by U-Pb geochronology and stratigraphy to constrain the evolution of the associated sedimentary basins. Preliminary results combined with published data suggest that inherited structures within the study area have evolved through different tectonic cycles, controlling the thicknes and the geometry of the sediments within the Mesozoic rift basin, the Miocene amount of exhumation in the basement-cored ranges and the deformation style of the associated foreland basins.

Geophysical Studies Based on Gravity and Seismic Data of Tule Desert, Meadow Valley Wash, and California Wash Basins, Southern Nevada

USGS Publications Warehouse

Scheirer, Daniel S.; Page, William R.; Miller, John J.

2006-01-01

Gravity and seismic data from Tule Desert, Meadow Valley Wash, and California Wash, Nevada, provide insight into the subsurface geometry of these three basins that lie adjacent to rapidly developing areas of Clark County, Nevada. Each of the basins is the product of Tertiary extension accommodated with the general form of north-south oriented, asymmetrically-faulted half-grabens. Geophysical inversion of gravity observations indicates that Tule Desert and Meadow Valley Wash basins are segmented into subbasins by shallow, buried basement highs. In this study, basement refers to pre-Cenozoic bedrock units that underlie basins filled with Cenozoic sedimentary and volcanic units. In Tule Desert, a small, buried basement high inferred from gravity data appears to be a horst whose placement is consistent with seismic reflection and magnetotelluric observations. Meadow Valley Wash consists of three subbasins separated by basement highs at structural zones that accommodated different styles of extension of the adjacent subbasins, an interpretation consistent with geologic mapping of fault traces oblique to the predominant north-south fault orientation of Tertiary extension in this area. California Wash is a single structural basin. The three seismic reflection lines analyzed in this study image the sedimentary basin fill, and they allow identification of faults that offset basin deposits and underlying basement. The degree of faulting and folding of the basin-fill deposits increases with depth. Pre-Cenozoic units are observed in some of the seismic reflection lines, but their reflections are generally of poor quality or are absent. Factors that degrade seismic reflector quality in this area are rough land topography due to erosion, deformed sedimentary units at the land surface, rock layers that dip out of the plane of the seismic profile, and the presence of volcanic units that obscure underlying reflectors. Geophysical methods illustrate that basin geometry is more complicated than would be inferred from extrapolation of surface topography and geology, and these methods aid in defining a three-dimensional framework to understand groundwater storage and flow in southern Nevada.

Prediction of hydrocarbons in sedimentary basins

USGS Publications Warehouse

Harff, J.E.; Davis, J.C.; Eiserbeck, W.

1993-01-01

To estimate the undiscovered hydrocarbon potential of sedimentary basins, quantitative play assessments specific for each location in a region may be obtained using geostatistical methods combined with the theory of classification of geological objects, a methodology referred to as regionalization. The technique relies on process modeling and measured borehole data as well as probabilistic methods to exploit the relationship between geology (the "predictor") and known hydrocarbon productivity (the "target") to define prospective stratigraphic intervals within a basin. It is demonstrated in case studies from the oil-producing region of the western Kansas Pennsylvanian Shelf and the gas-bearing Rotliegend sediments of the Northeast German Basin. ?? 1993 International Association for Mathematical Geology.

Geochemistry of shale and sedimentary pyrite as a proxy for gold fertility in the Selwyn basin area, Yukon

NASA Astrophysics Data System (ADS)

Sack, Patrick J.; Large, Ross R.; Gregory, Daniel D.

2018-01-01

Selwyn basin area strata contain sedimentary pyrite with Au above background levels when analyzed by laser ablation-inductively coupled mass spectrometry. Hyland Group rocks contain framboidal pyrite contents of 670 ppb Au, 1223 ppm As, and 5.3 ppm Te; the mean of all types of sedimentary pyrite in the Hyland Group is 391 ppb Au, 1489 ppm As, and 3.8 ppm Te. These levels are similar to sedimentary pyrite in host lithologies from major orogenic gold districts in New Zealand and Australia. Comparison of whole rock and pyrite data show that rocks deposited in continental slope settings with significant terrigenous input contain pyrite that is consistently enriched in Au, As, Te, Co, and Cu. Although data are limited, whole rock samples of stratigraphic units containing Au-rich pyrite also contain high Au, indicating that most of the Au is within sedimentary pyrite. Based on geologic characteristics and comparison of pyrite chemistry data with whole rock chemistry, Selwyn basin area strata have the necessary ingredients to form orogenic gold deposits: Au-enriched source rocks, metamorphic conditions permissive of forming a metamorphic ore fluid, and abundant structural preparation for channeling fluids and depositing ore.

Petroleum prospects for offshore sedimentary basins in the eastern Papua New Guinea and Solomon Islands regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruns, T.R.; Vedder, J.G.

Intra-arc basins in the Buka-Bougainville region of Papua New Guinea and in the Solomon Islands contain thick sedimentary sequences that may be prospective for petroleum. The Queen Emma basin, between Bougainville and New Ireland, contains as much as 8 km of deformed Oligocene and younger strata. The Central Solomons Trough, which underlies New Georgia Sound, is a composite intra-arc basin that contains late Oligocene and younger strata as much as 7 km thick. Farther east, beneath Indispensable Strait, the down-faulted Indispensable basin locally contains as much as 5.4 km of Miocene( ) and younger strata, and the offshore part ofmore » Mbokokimbo basin off eastern Guadalcanal includes 6 km or more of late Miocene and younger strata. All of these basins have some of the attributes necessary to generate and trap petroleum. Structural and stratigraphic traps are common, including faulted anticlines, sedimentary wedges, and carbonate reefs and reef-derived deposits on submarine ridges and along the basin margins. The thickness of the basin deposits ensures that some strata are buried deeply enough to be within the thermal regime required for hydrocarbon generation. However, little source or reservoir rock information is available because of the lack of detailed surface and subsurface stratigraphy. Moreover, much of the basin sediment is likely to consist of volcaniclastic material, derived from uplifted volcanogenic rocks surrounding the basins, and may be poor in source and reservoir rocks. Until additional stratigraphic information is available, analysis of the petroleum potential of these basins is a matter of conjecture.« less

Sedimentary and tectonic evolution of Plio Pleistocene alluvial and lacustrine deposits of Fucino Basin (central Italy)

NASA Astrophysics Data System (ADS)

Cavinato, Gian Paolo; Carusi, Claudio; Dall'Asta, Massimo; Miccadei, Enrico; Piacentini, Tommaso

2002-04-01

The Fucino Basin was the greatest lake of the central Italy, which was completely drained at the end of 19th century. The basin is an intramontane half-graben filled by Plio-Quaternary alluvial and lacustrine deposits located in the central part of the Apennines chain, which was formed in Upper Pliocene and in Quaternary time by the extensional tectonic activity. The analysis of the geological surface data allows the definition of several stratigraphic units grouped in Lower Units and Upper Units. The Lower Units (Upper Pliocene) are exposed along the northern and north-eastern basin margins. They consist of open to marginal lacustrine deposits, breccia deposits and fluvial deposits. The Upper Units (Lower Pliocene-Holocene) consist of interbedded marginal lacustrine deposits and fluvial deposits; thick coarse-grained fan-delta deposits are interfingered at the foot of the main relief with fluvial-lacustrine deposits. Most of the thickness of the lacustrine sequences (more than 1000-m thick) is buried below the central part of the Fucino Plain. The basin is bounded by E-W, WSW-ENE and NW-SE fault systems: Velino-Magnola Fault (E-W) and Tremonti-Celano-Aielli Fault (WSW-ENE) and S. Potito-Celano Fault (NW-SE) in the north; the Trasacco Fault, the Pescina-Celano Fault and the Serrone Fault (NW-SE) in the south-east. The geometry and kinematic indicators of these faults indicate normal or oblique movements. The study of industrial seismic profiles across the Fucino Basin gives a clear picture of the subsurface basin geometry; the basin shows triangular-shaped basin-fill geometry, with the maximum deposits thickness toward the main east boundary fault zones that dip south-westward (Serrone Fault, Trasacco Fault, Pescina-Celano Fault). On the basis of geological surface data, borehole stratigraphy and seismic data analysis, it is possible to recognize and to correlate sedimentary and seismic facies. The bottom of the basin is well recognized in the seismic lines available from the good and continuous signals of the top of Meso-Cenozoic carbonate rocks. The shape of sedimentary bodies indicates that the filling of the basin was mainly controlled by normal slip along the NW-SE boundary faults. In fact, the continental deposits are frequently in on-lap contact over the carbonate substratum; several disconformable contacts occurred during the sedimentary evolution of the basin. The main faults (with antithetic and synthetic fault planes) displace the whole sedimentary sequence up to the surface indicating a recent faults' activity (1915 Avezzano earthquake, Ms=7.0). The stratigraphic and tectonic setting of the Fucino Basin and neighboring areas indicates that the extensional tectonic events have had an important role in driving the structural-sedimentary evolution of the Plio-Quaternary deposits. The geometry of the depositional bodies, of the fault planes and their relationships indicate that the Fucino Basin was formed as a half-graben type structure during Plio-Quaternary extensional events. Some internal complexities are probably related to the fold-and-thrust structures of the Apenninic orogeny formed in Messinian time, in this area, and to a different activity timing of the E-W and WSW-ENE fault systems and the NW-SE fault systems. We believe, based on the similarity of the surface characteristics, that the structural setting of the Fucino Basin can be extrapolated to the other great intramontane basins in Central Italy (e.g. Rieti, L'Aquila, Sulmona, Sora, Isernia basins).

The chronostratigraphic framework of the South-Pyrenean Maastrichtian succession reappraised: Implications for basin development and end-Cretaceous dinosaur faunal turnover

NASA Astrophysics Data System (ADS)

Fondevilla, Víctor; Dinarès-Turell, Jaume; Oms, Oriol

2016-05-01

The evolution of the end-Cretaceous terrestrial ecosystems and faunas outside of North America is largely restricted to the European Archipelago. The information scattered in this last area can only be integrated in a chronostratigraphic framework on the basis of robust age constraints and stratigraphy. Therefore, we have revisited the puzzling age calibration of the sedimentary infilling from the Isona sector in the Tremp syncline (South-Central Pyrenees), an area renowned for its rich Maastrichtian dinosaur fossil record. Aiming to shed light to existing controversial age determinations, we carried out a new magnetostratigraphic study along the ~ 420 m long Orcau and Nerets sections of that area. Our results reveal that most of the succession correlates to the early Maastrichtian (mostly chron C31r) in accordance to ages proposed by recent planktonic foraminifera biostratigraphy. The resulting chronostratigraphic framework of the entire Maastrichtian basin recorded in the Tremp syncline shows that a significant sedimentary hiatus of about 3 My characterizes most of the late Maastrichtian in the study area. This hiatus, related to an abrupt migration of the basin depocenter, is temporally close to similar hiatuses, decreases in sedimentary rates and facies shifts recorded in other southwestern European areas. The present chronologic framework sets the basis for a thorough assessment of end-Cretaceous terrestrial faunal turnover and extinction patterns, and the establishment of a more rigorous Pyrenean basin evolution analysis.

Potassium metasomatism of volcanic and sedimentary rocks in rift basins, calderas and detachment terranes

NASA Technical Reports Server (NTRS)

Chapin, C. E.; drographic basins.

1985-01-01

The chemical, mineralogical, and oxygen-isotopic changes accompanying K-metasomatism are described. The similarities with diagenetic reactions in both deep marine and alkaline, saline-lake environments are noted. The common occurrence of K-metasomatism in upper-plate rocks of detachment terranes indicates that the early stage of severe regional extension causes crustal downwarping and, in arid to semi-arid regions, development of closed hydrographic basins.

BasinVis 1.0: A MATLAB®-based program for sedimentary basin subsidence analysis and visualization

NASA Astrophysics Data System (ADS)

Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

2016-06-01

Stratigraphic and structural mapping is important to understand the internal structure of sedimentary basins. Subsidence analysis provides significant insights for basin evolution. We designed a new software package to process and visualize stratigraphic setting and subsidence evolution of sedimentary basins from well data. BasinVis 1.0 is implemented in MATLAB®, a multi-paradigm numerical computing environment, and employs two numerical methods: interpolation and subsidence analysis. Five different interpolation methods (linear, natural, cubic spline, Kriging, and thin-plate spline) are provided in this program for surface modeling. The subsidence analysis consists of decompaction and backstripping techniques. BasinVis 1.0 incorporates five main processing steps; (1) setup (study area and stratigraphic units), (2) loading well data, (3) stratigraphic setting visualization, (4) subsidence parameter input, and (5) subsidence analysis and visualization. For in-depth analysis, our software provides cross-section and dip-slip fault backstripping tools. The graphical user interface guides users through the workflow and provides tools to analyze and export the results. Interpolation and subsidence results are cached to minimize redundant computations and improve the interactivity of the program. All 2D and 3D visualizations are created by using MATLAB plotting functions, which enables users to fine-tune the results using the full range of available plot options in MATLAB. We demonstrate all functions in a case study of Miocene sediment in the central Vienna Basin.

Integrated Potential-field Studies in Support of Energy Resource Assessment in Frontier Areas of Alaska

NASA Astrophysics Data System (ADS)

Phillips, J. D.; Saltus, R. W.; Potter, C. J.; Stanley, R. G.; Till, A. B.

2008-05-01

In frontier areas of Alaska, potential-field studies play an important role in characterizing the geologic structure of sedimentary basins having potential for undiscovered oil and gas resources. Two such areas are the Yukon Flats basin in the east-central interior of Alaska, and the coastal plain of the Arctic National Wildlife Refuge (ANWR) in northeastern Alaska. The Yukon Flats basin is a potential source of hydrocarbon resources for local consumption and possible export. Knowledge of the subsurface configuration of the basin is restricted to a few seismic reflection profiles covering a limited area and one well. The seismic profiles were reprocessed and reinterpreted in preparation for an assessment of the oil and gas resources of the basin. The assessment effort required knowledge of the basin configuration away from the seismic profiles, as well as an understanding of the nature of the underlying basement. To extend the interpretation of the basin thickness across the entire area of the basin, an iterative Jachens-Moring gravity inversion was performed on gridded quasi-isostatic residual gravity anomaly data. The inversion was constrained to agree with the interpreted basement surface along the seismic profiles. In addition to the main sedimentary depocenter interpreted from the seismic data as having over 8 km of fill, the gravity inversion indicated a depocenter with over 7 km of fill in the Crooked Creek sub-basin. Results for the Crooked Creek sub-basin are consistent with magnetic and magnetotelluric modeling, but they await confirmation by drilling or seismic profiling. Whether hydrocarbon source rocks are present in the pre-Cenozoic basement beneath Yukon Flats is difficult to determine because extensive surficial deposits obscure the bedrock geology, and no deep boreholes penetrate basement. The color and texture patterns in a red-green-blue composite image consisting of reduced-to-the-pole aeromagnetic data (red), magnetic potential (blue), and basement gravity (green) highlight domains with common geophysical characteristics and, by inference, lithology. The observed patterns suggest that much of the basin is underlain by Devonian to Jurassic oceanic rocks that probably have little or no potential for hydrocarbon generation. The coastal plain surficial deposits in the northern part of ANWR conceal another frontier basin with hydrocarbon potential. Proprietary aeromagnetic and gravity data were used, along with seismic reflection profiles, to construct a structural and stratigraphic model of this highly deformed sedimentary basin for use in an energy resource assessment. Matched-filtering techniques were used to separate short-wavelength magnetic and gravity anomalies attributed to sources near the top of the sedimentary section from longer-wavelength anomalies attributed to deeper basin and basement sources. Models along the seismic reflection lines indicate that the primary sources of the short-wavelength anomalies are folded and faulted sedimentary beds truncated at the Pleistocene erosion surface. In map view, the aeromagnetic and gravity anomalies produced by the sedimentary units were used to identify possible structural trapping features and geometries, but they also indicated that these features may be significantly disrupted by faulting.

Palaeoredox conditions and sequence stratigraphy of the Cretaceous storm-dominated, mixed siliciclastic-carbonate ramp in the Eastern Cordillera Basin (Colombia): Evidence from sedimentary geochemical proxies and facies analysis

NASA Astrophysics Data System (ADS)

Rivera, Huber A.; Le Roux, Jacobus P.; Sánchez, L. Katherine; Mariño-Martínez, Jorge E.; Salazar, Christian; Barragán, J. Carolina

2018-10-01

The Cretaceous black shales of Colombia are among the most important successions in the north of South America and have attracted the attention of many geoscientists and exploration companies over the last few decades, because of their high hydrocarbon potential and the presence of emerald deposits. However, many uncertainties still remain with regard to their tectonic setting, sequence stratigraphy, depositional environments, palaeoxygenation conditions, and organic matter preservation. In order to develop a more integrated picture of these different processes and conditions, we conducted a detailed sedimentological, inorganic geochemical (U, V, Ni, Zn, Mn, Fe, Ti, Mo, Cu, Cr, Cd, Ba) and sequence stratigraphic analysis of the Cretaceous black shales in the Magdalena-Tablazo Sub-Basin (Eastern Cordillera Basin) of Colombia. Eleven lithofacies and five lithofacies associations of a storm-dominated, siliciclastic-carbonate ramp were identified, which range from basin to shallow inner ramp environments. These facies were grouped into six third-order stratigraphic sequences showing high-order cycles of marine transgression with constrained regressive pulses during the late Valanginian to early Coniacian. The black shales succession represents deposition under anoxic bottom water with some intervals representing dysoxic-suboxic conditions. The evolution of the sedimentary environments and their palaeoxygenation history reflect tectonic and eustatic sea-level controls that 1) produced a variable orientation and position of the coastline throughout the Cretaceous; 2) conditioned the low-gradient ramp geometry (<0.3°) and 3) modified the oxygenation conditions in the Magdalena-Tablazo Sub-Basin. An improved understanding of the sedimentary setting during deposition of the Cretaceous black shales in the Magdalena-Tablazo Sub-Basin assists in highlighting the interplay between the mechanism of sedimentation and continuum anoxic conditions prevailing in a basin, as well the important role of nutrient input from continental runoff as a trigger of high productivity and extended anoxia conditions.

Active transtensional intracontinental basins: Walker Lane in the western Great Basin

USGS Publications Warehouse

Jayko, Angela S.; Bursik, Marcus

2012-01-01

The geometry and dimensions of sedimentary basins within the Walker Lane are a result of Plio-Pleistocene transtensive deformation and partial detachment of the Sierra Nevada crustal block from the North American plate. Distinct morpho-tectonic domains lie within this active transtensive zone. The northeast end of the Walker Lane is partly buried by active volcanism of the southern Cascades, and adjacent basins are filled or poorly developed. To the south, the basin sizes are moderate, 25–45km × 15–10 km, with narrow 8-12km wide mountain ranges mainly oriented N-S to NNE. These basins form subparallel arrays in discrete zones trending about 300° and have documented clockwise rotation. This is succeeded to the south by a releasing stepover domain ∼85-100km wide, where the basins are elongated E-W to ENE, small (∼15-30km long, 5-15km wide), and locally occupied by active volcanic centers. The southernmost part of the Walker Lane is structurally integrated, with high to extreme relief. Adjacent basins are elongate, 50-200km long and ∼5 -20km wide. Variations in transtensive basin orientations in the Walker Lane are largely attributable to variations in strain partitioning. Large basins in the Walker Lane have 2-6km displacement across basin bounding faults with up to 3 km of clastic accumulation based on gravity and drill hole data. The sedimentary deposits of the basins may include interbedded volcanic deposits with bimodal basaltic and rhyolitic associations. The basins may include lacustrine deposits that record a wide range of water chemistry from cold fresh water conditions to saline-evaporative

The Argyre Region as a Prime Target for in situ Astrobiological Exploration of Mars.

PubMed

Fairén, Alberto G; Dohm, James M; Rodríguez, J Alexis P; Uceda, Esther R; Kargel, Jeffrey; Soare, Richard; Cleaves, H James; Oehler, Dorothy; Schulze-Makuch, Dirk; Essefi, Elhoucine; Banks, Maria E; Komatsu, Goro; Fink, Wolfgang; Robbins, Stuart; Yan, Jianguo; Miyamoto, Hideaki; Maruyama, Shigenori; Baker, Victor R

2016-02-01

At the time before ∼3.5 Ga that life originated and began to spread on Earth, Mars was a wetter and more geologically dynamic planet than it is today. The Argyre basin, in the southern cratered highlands of Mars, formed from a giant impact at ∼3.93 Ga, which generated an enormous basin approximately 1800 km in diameter. The early post-impact environment of the Argyre basin possibly contained many of the ingredients that are thought to be necessary for life: abundant and long-lived liquid water, biogenic elements, and energy sources, all of which would have supported a regional environment favorable for the origin and the persistence of life. We discuss the astrobiological significance of some landscape features and terrain types in the Argyre region that are promising and accessible sites for astrobiological exploration. These include (i) deposits related to the hydrothermal activity associated with the Argyre impact event, subsequent impacts, and those associated with the migration of heated water along Argyre-induced basement structures; (ii) constructs along the floor of the basin that could mark venting of volatiles, possibly related to the development of mud volcanoes; (iii) features interpreted as ice-cored mounds (open-system pingos), whose origin and development could be the result of deeply seated groundwater upwelling to the surface; (iv) sedimentary deposits related to the formation of glaciers along the basin's margins, such as evidenced by the ridges interpreted to be eskers on the basin floor; (v) sedimentary deposits related to the formation of lakes in both the primary Argyre basin and other smaller impact-derived basins along the margin, including those in the highly degraded rim materials; and (vi) crater-wall gullies, whose morphology points to a structural origin and discharge of (wet) flows.

Analysis of Site Effect in the Izmit Basin of Turkey by Wave Propagation Simulation Using the Spectral Element Method: Preliminary Results

NASA Astrophysics Data System (ADS)

Firtana Elcomert, K.; Kocaoglu, A. H.

2013-12-01

Sedimentary basins generally cause significant ground motion amplification during an earthquake. Along with the resonance controlled by the impedance contrast between the sedimentary cover and bedrock, surface waves generated within the basin make the waveforms more complex and longer in duration. When a dense network of weak and/or strong motion sensors is available, site effect or more specifically sedimentary basin amplification can be directly estimated experimentally provided that significant earthquakes occur during the period of study. Alternatively, site effect can be investigated through simulation of ground motion. The objective of this study is to investigate the 2-D and/or 3-D site effect in the Izmit Basin located in the eastern Marmara region of Turkey, using the currently available bedrock topography and shear-wave velocity data. The Izmit Basin was formed in Plio-Quaternary period and is known to be controlled by the northern branch of the North Anatolian Fault Zone. A thorough analysis of seismic hazard is important since the city of Izmit and its metropolitan area is located in this region. This work presents some of the preliminary results obtained from 2-D and 3-D seismic wave propagation simulations using the spectral element method, which is based on high order polynomial approximation of the weak formulation of the wave equation. In this study, the numerical simulations were carried out with SPECFEM2D/3D program. Comparison of seismograms recorded on the top of sedimentary layer with those recorded on the bedrock show more complex waveforms with higher amplitudes on seismograms recorded at the free surface. Furthermore, modeling clearly reveals that observed seismograms include surface waves whose excitation is clearly related with the basin geometry.

Subglacial sedimentary basin characterization of Wilkes Land, East Antarctica via applied aerogeophysical inverse methods

NASA Astrophysics Data System (ADS)

Frederick, B. C.; Gooch, B. T.; Richter, T.; Young, D. A.; Blankenship, D. D.; Aitken, A.; Siegert, M. J.

2013-12-01

Topography, sediment distribution and heat flux are all key boundary conditions governing the stability of the East Antarctic ice sheet (EAIS). Recent scientific scrutiny has been focused on several large, deep, interior EAIS basins including the submarine basal topography characterizing the Aurora Subglacial Basin (ASB). Numerical ice sheet models require accurate deformable sediment distribution and lithologic character constraints to estimate overall flow velocities and potential instability. To date, such estimates across the ASB have been derived from low-resolution satellite data or historic aerogeophysical surveys conducted prior to the advent of GPS. These rough basal condition estimates have led to poorly-constrained ice sheet stability models for this remote 200,000 sq km expanse of the ASB. Here we present a significantly improved quantitative model characterizing the subglacial lithology and sediment in the ASB region. The product of comprehensive ICECAP (2008-2013) aerogeophysical data processing, this sedimentary basin model details the expanse and thickness of probable Wilkes Land subglacial sedimentary deposits and density contrast boundaries indicative of distinct subglacial lithologic units. As part of the process, BEDMAP2 subglacial topographic results were improved through the additional incorporation of ice-penetrating radar data collected during ICECAP field seasons 2010-2013. Detailed potential field data pre-processing was completed as well as a comprehensive evaluation of crustal density contrasts based on the gravity power spectrum, a subsequent high pass data filter was also applied to remove longer crustal wavelengths from the gravity dataset prior to inversion. Gridded BEDMAP2+ ice and bed radar surfaces were then utilized to establish bounding density models for the 3D gravity inversion process to yield probable sedimentary basin anomalies. Gravity inversion results were iteratively evaluated against radar along-track RMS deviation and gravity and magnetic depth to basement results. This geophysical data processing methodology provides a substantial improvement over prior Wilkes Land sedimentary basin estimates yielding a higher resolution model based upon iteration of several aerogeophysical datasets concurrently. This more detailed subglacial sedimentary basin model for Wilkes Land, East Antarctica will not only contribute to vast improvements on EAIS ice sheet model constraints, but will also provide significant quantifiable controls for subglacial hydrologic and geothermal flux estimates that are also sizable contributors to the cold-based, deep interior basal ice dynamics dominant in the Wilkes Land region.

Seismic interpretation and thrust tectonics of the Amadeus Basin, central Australia, along the BMR regional seismic line

NASA Astrophysics Data System (ADS)

Shaw, Russell D.; Korsch, Russell J.; Wright, C.; Goleby, B. R.

At the northern margin of the Amadeus Basin the monoclinal upturn (the MacDonnell Homocline) is interpreted to be the result of rotation and limited back-thrusting of the sedimentary sequence in front of a southerly-directed, imbricate basement thrust-wedge. This thrust complex is linked at depth to the crust-cutting Redbank Thrust Zone. In the northern part of the basin immediately to the south, regional seismic reflection profiling across the Missionary Plain shows a sub-horizontal, north-dipping, parautochthonous sedimentary sequence between about 8.5 km and 12.0 km thick. This sedimentary sequence shows upturning only at the northern and southern extremities, and represents an unusual, relatively undeformed region between converging thrust systems. In this intervening region, the crust appears to have been tilted downwards and northwards in response to the upthrusting to the north. Still farther to the south, the vertical uplift of the southern hanging wall of the Gardiner Thrust is about 6 km. Seismic reflection profiling in the region immediately south of the Gardiner Thrust indicates repetition of the sedimentary sequence. At the far end of the profile, in the Kernot Range, an imbricate thrust system fans ahead of a ramp-flat thrust pair. This thrust system (the Kernot Range Thrust System) occurs immediately north of an aeromagnetic domain boundary which marks the southern limit of a central ridge region characterized by thin Palaeozoic sedimentary cover and shallow depths to magnetic basement. A planar seismic event, imaged to a depth of at least 18 km, may correspond to the same boundary and is interpreted as a pre-basin Proterozoic thrust. Overall, the structure in the shallow sedimentary section in the central-southern region of the Amadeus Basin indicates that north-directed thrusting during the Dovonian-Carboniferous Alice Springs Orogeny was thin-skinned. During this orogeny an earlier thrust system, formed during the Petermann Ranges Orogeny and precursor orogenies in the Late Proterozoic, was reactivated with Proterozoic salt deposits localising the decollement zone. The Alice Springs Orogeny also reactivated a major mid Proterozoic province boundary in the basement to the north of the basin, resulting in major thrust movement at the northern basin margin.

Maps showing sedimentary basins, surface thermal maturity, and indications of petroleum in the Central Alaska Province

USGS Publications Warehouse

Troutman, Sandra M.; Stanley, Richard G.

2003-01-01

This publication includes two maps (at 1:2,500,000 scale) and a pamphlet that describe sedimentary basins, surface thermal maturity, and 95 reported occurrences of petroleum in natural seeps, wells, and rock outcrops in central Alaska. No commercial petroleum production has been obtained from central Alaska, in contrast to the prolific deposits of oil and gas that have been found and developed in northern Alaska and the Cook Inlet region. Nevertheless, confirmed indications of petroleum in central Alaska include (1) natural seeps of methane gas on the Yukon Delta; (2) occurrences of methane gas in wells in the Bethel, Kotzebue, Nenana, Northway, and Yukon Flats basins; (3) oil and methane gas in seeps and wells in Norton Sound; (4) small quantities of liquid and solid hydrocarbons associated with mercury ore in the Kuskokwim Mountains; (5) oil shale and numerous occurrences of bitumen in the Kandik area; and (6) tasmanite, a form of oil shale, in the uplands north of Yukon Flats.

Vast geologic basins attract Indonesian oil exploration. Pt. 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soeparjadi, R.A.; Slocum, R.C.

1973-10-01

This concluding article of a 3-part series describes key geologic features that make Indonesia's S. and E. Kalimantan, Irian Jaya, and S. China Sea areas prime targets for continuing oil and gas exploration. Thick sedimentary basins in E. Kalimantan contain Indonesia'a largest offshore oilfield and other important developments. New reef discoveries in Irian Jaya highlight an extensive exploration effort. Continued drilling in the huge S. China Sea is assured by near commercial shows in recent wildcats. While many thousands of square miles still do not claim a significant discovery, proven successes such as Kalimantan's Attaka field (Indonesia's largest offshore producer)more » and Irian Jaya's new 23,600 bopd Kasim 3 well provide ample incentive for intensive oil searches. Near commercial recoveries of both gas and oil in Indonesia's huge S. China Sea and the recent testing of a 6,000 bopd oil well in nearby Malaysian waters spur interest in the area's W. Natuna and Miri-Seria sedimentary basins.« less

Thermal evolution of sedimentary basins in Alaska

USGS Publications Warehouse

Johnsson, Mark J.; Howell, D.G.

1996-01-01

The complex tectonic collage of Alaska is reflected in the conjunction of rocks of widely varying thermal maturity. Indicators of the level of thermal maturity of rocks exposed at the surface, such as vitrinite reflectance and conodont color alteration index, can help constrain the tectonic evolution of such complex regions and, when combined with petrographic, modern heat flow, thermogeochronologic, and isotopic data, allow for the detailed evaluation of a region?s burial and uplift history. We have collected and assembled nearly 10,000 vitrinite-reflectance and conodont-color-alteration index values from the literature, previous U.S. Geological Survey investigations, and our own studies in Alaska. This database allows for the first synthesis of thermal maturity on a broadly regional scale. Post-accretionary sedimentary basins in Alaska show wide variability in terms of thermal maturity. The Tertiary interior basins, as well as some of the forearc and backarc basins associated with the Aleutian Arc, are presently at their greatest depth of burial, with immature rocks exposed at the surface. Other basins, such as some backarc basins on the Alaska Peninsula, show higher thermal maturities, indicating modest uplift, perhaps in conjunction with higher geothermal gradients related to the arc itself. Cretaceous ?flysch? basins, such as the Yukon-Koyukuk basin, are at much higher thermal maturity, reflecting great amounts of uplift perhaps associated with compressional regimes generated through terrane accretion. Many sedimentary basins in Alaska, such as the Yukon-Koyukuk and Colville basins, show higher thermal maturity at basin margins, perhaps reflecting greater uplift of the margins in response to isostatic unloading, owing to erosion of the hinterland adjacent to the basin or to compressional stresses adjacent to basin margins.

Thermal regimes of Malaysian sedimentary basins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdul Halim, M.F.

1994-07-01

Properly corrected and calibrated thermal data are important in estimating source-rock maturation, diagenetics, evolution of reservoirs, pressure regimes, and hydrodynamics. Geothermal gradient, thermal conductivity, and heat flow have been determined for the sedimentary succession penetrated by exploratory wells in Malaysia. Geothermal gradient and heat-flow maps show that the highest average values are in the Malay Basin. The values in the Sarawak basin are intermediate between those of the Malay basin and the Sabah Basin, which contains the lowest average values. Temperature data were analyzed from more than 400 wells. An important parameter that was studied in detail is the circulationmore » time. The correct circulation time is essential in determining the correct geothermal gradient of a well. It was found that the most suitable circulation time for the Sabah Basin is 20 hr, 30 hr for the Sarawak Basin and 40 hr for the Malay Basin. Values of thermal conductivity, determined from measurement and calibrated calculations, were grouped according to depositional units and cycles in each basin.« less

Spatial and Temporal Strain Distribution Along the Central Red Sea Rift - A Study of the Hamd-Jizil Basin in Saudi Arabia

NASA Astrophysics Data System (ADS)

Szymanski, E.; Stockli, D.; Johnson, P.; Kattan, F. H.; Al Shamari, A.

2006-12-01

Numerous models exploring the rupturing modes and mechanisms of continental lithosphere are based on geological evidence from the Red Sea/Gulf of Suez rift system. Individually, the Red Sea basin is the prototype for many models of orthogonal continental rifting. Despite being a classic example of continental extension, many temporal and spatial strain distribution aspects, as well as the dynamic evolution of the rift architecture of the Red Sea, remain poorly constrained. Critical data come mostly from the Gulf of Suez and the Egyptian and Yemeni margins of the Red Sea; the rift flanks in Sudan and Saudi Arabia have remained largely unstudied, leaving a large information gap along the central portions of the rift system. Improving continental lithosphere rupture models requires an absolute understanding of the timing and magnitude of strain partitioning along the full rift flank. This study focuses on the development of extensional structures, syn- extensional sedimentary deposits, and rift-related Tertiary basaltic volcanism along the central flank of the rift system in Saudi Arabia. Geo- and thermochronometric techniques are used to elucidate the evolution of inboard and outboard strain markers manifested by structurally-controlled extensional basins that parallel the trend of the main Red Sea rift. Constraints on the dynamics of rift flank deformation are achieved through the collection of thermochronometric transects that traverse both the entire Arabian shield and individual normal faults that bound inland basins. Preliminary results show inland basins as asymmetric half-grabens filled by tilted Cenozoic sedimentary strata and separated by exhumed basement fault blocks. The most prominent extensional basin is the NW-trending Hamd-Jizil basin, located north of Madinah, measuring ~200 km along strike and up to 20 km in width. The Hamd-Jizil basin is structurally characterized by two half-grabens exposing a series of syn-rift siliciclastic sedimentary sections below Tertiary basalts. In certain areas, thick basalt sequences provide basin infill and appear faulted by a younger series of normal faults. Work continues on the production of further geo- and thermochronologic data for the Tertiary basalt sequences as well as the entire rift flank region.

Geologic evolution and sequence stratigraphy of the offshore Pelotas Basin, southeast Brazil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abreu, V.S.

1996-01-01

The Brazilian marginal basins have been studied since the beginning of the 70s. At least nine large basins are distributed along the entire Eastern continental margin. The sedimentary infill of these basins consists of lower Cretaceous (continental/lacustrine) rift section underlying marine upper Cretaceous (carbonate platforms) and marine upper Cretaceous/Tertiary sections, corresponding to the drift phase. The sedimentary deposits are a direct result of the Jurassic to lower Cretaceous break-up of the Pangea. This study will focus on the geologic evolution and sequence stratigraphic analysis of the Pelotas basin (offshore), located in the Southeast portion of the Brazilian continental margin betweenmore » 28[degrees] and 34[degrees] S, covering approximately 50,000 Km[sup 2]. During the early Cretaceous, when the break-up of the continent began in the south, thick basaltic layers were deposited in the Pelotas basin. These basalts form a thick and broad wedge of dipping seaward reflections interpreted as a transitional crust. During Albian to Turonian times, due to thermal subsidence, an extensive clastic/carbonate platform was developed, in an early drift stage. The sedimentation from the upper Cretaceous to Tertiary was characterized by a predominance of siliciclastics in the southeast margin, marking an accentuate deepening of the basin, showing several cycles related to eustatic fluctuations. Studies have addressed the problems of hydrocarbon exploration in deep water setting within a sequence stratigraphic framework. Thus Pelotas basin can provide a useful analogue for exploration efforts worldwide in offshore passive margins.« less

Geologic evolution and sequence stratigraphy of the offshore Pelotas Basin, southeast Brazil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abreu, V.S.

1996-12-31

The Brazilian marginal basins have been studied since the beginning of the 70s. At least nine large basins are distributed along the entire Eastern continental margin. The sedimentary infill of these basins consists of lower Cretaceous (continental/lacustrine) rift section underlying marine upper Cretaceous (carbonate platforms) and marine upper Cretaceous/Tertiary sections, corresponding to the drift phase. The sedimentary deposits are a direct result of the Jurassic to lower Cretaceous break-up of the Pangea. This study will focus on the geologic evolution and sequence stratigraphic analysis of the Pelotas basin (offshore), located in the Southeast portion of the Brazilian continental margin betweenmore » 28{degrees} and 34{degrees} S, covering approximately 50,000 Km{sup 2}. During the early Cretaceous, when the break-up of the continent began in the south, thick basaltic layers were deposited in the Pelotas basin. These basalts form a thick and broad wedge of dipping seaward reflections interpreted as a transitional crust. During Albian to Turonian times, due to thermal subsidence, an extensive clastic/carbonate platform was developed, in an early drift stage. The sedimentation from the upper Cretaceous to Tertiary was characterized by a predominance of siliciclastics in the southeast margin, marking an accentuate deepening of the basin, showing several cycles related to eustatic fluctuations. Studies have addressed the problems of hydrocarbon exploration in deep water setting within a sequence stratigraphic framework. Thus Pelotas basin can provide a useful analogue for exploration efforts worldwide in offshore passive margins.« less

Pliocene transpressional modification of depositional basins by convergent thrusting adjacent to the "Big Bend" of the San Andreas fault: An example from Lockwood Valley, southern California

USGS Publications Warehouse

Kellogg, K.S.; Minor, S.A.

2005-01-01

The "Big Bend" of the San Andreas fault in the western Transverse Ranges of southern California is a left stepping flexure in the dextral fault system and has long been recognized as a zone of relatively high transpression compared to adjacent regions. The Lockwood Valley region, just south of the Big Bend, underwent a profound change in early Pliocene time (???5 Ma) from basin deposition to contraction, accompanied by widespread folding and thrusting. This change followed the recently determined initiation of opening of the northern Gulf of California and movement along the southern San Andreas fault at about 6.1 Ma, with the concomitant formation of the Big Bend. Lockwood Valley occupies a 6-km-wide, fault-bounded structural basin in which converging blocks of Paleoproterozoic and Cretaceous crystalline basement and upper Oligocene and lower Miocene sedimentary rocks (Plush Ranch Formation) were thrust over Miocene and Pliocene basin-fill sedimentary rocks (in ascending order, Caliente Formation, Lockwood Clay, and Quatal Formation). All the pre-Quatal sedimentary rocks and most of the Pliocene Quatal Formation were deposited during a mid-Tertiary period of regional transtension in a crustal block that underwent little clockwise vertical-axis rotation as compared to crustal blocks to the south. Ensuing Pliocene and Quaternary transpression in the Big Bend region began during deposition of the poorly dated Quatal Formation and was marked by four converging thrust systems, which decreased the areal extent of the sedimentary basin and formed the present Lockwood Valley structural basin. None of the thrusts appears presently active. Estimated shortening across the center of the basin was about 30 percent. The fortnerly defined eastern Big Pine fault, now interpreted to be two separate, oppositely directed, contractional reverse or thrust faults, marks the northwestern structural boundary of Lockwood Valley. The complex geometry of the Lockwood Valley basin is similar to other Tertiary structural basins in southern California, such those that underlie Cuyama Valley, the Ridge basin, and the east Ventura basin.

Aptian sedimentation in the Recôncavo-Tucano-Jatobá Rift System and its tectonic and paleogeographic significance

NASA Astrophysics Data System (ADS)

Freitas, Bernardo T.; Almeida, Renato P.; Carrera, Simone C.; Figueiredo, Felipe T.; Turra, Bruno B.; Varejão, Filipe G.; Assine, Mario L.

2017-12-01

This study, based on detailed sedimentologic and stratigraphic analysis of the Aptian succession preserved in the Recôncavo-Tucano-Jatobá Rift System (RTJ), present new elements for biostratigraphic correlation and paleogeographic reconstruction in the mid-Cretaceous South Atlantic realm, supporting novel interpretations on the tectonic and sedimentary evolution related to the W-Gondwana breakup. The Aptian sedimentary succession in the RTJ has been referred to as Marizal Formation, and interpreted as post-rift deposits. Detailed sedimentologic and stratigraphic studies of these deposits enabled the recognition and individualization of two distinctive sedimentary units that can be traced in the entire RTJ. These units are here described and named Banzaê and Cícero Dantas members of the Marizal Formation. Their contact is locally marked by the fossiliferous successions of the here proposed Amargosa Bed, lying at the top of the Banzaê Member. Both members of the Marizal Formation record large river systems captured by the Tucano Basin with the local development of eolian dune fields and fault-bounded alluvial fans. The Amargosa Bed represents a regional-scale base level change preserved between the Aptian fluvial successions along the RTJ. Hence, the studied sedimentary record presents important implications for the timing and direction of marine ingressions affecting NE-Brazil interior basins during the Aptian. A remarkable contrast in preserved fluvial architecture between the Banzaê Member, characterized by connected channel bodies, and the Cícero Dantas Member, characterized by isolated channel bodies within overbank fines, is here reported. The main interpreted control for the observed contrast in fluvial stratigraphy is sedimentary yield variation. The interval is also subject to the interpretation of a regional shift in the mechanism responsible for the subsidence of the basins formed during the Cretaceous break-up of the Central South Atlantic. This view is challenged by our results which reveal that basin forming extension continued throughout the Aptian. As a conclusion, the detailed stratigraphy of the Marizal Formation forward alternative geodynamic interpretations for the Aptian successions in northeastern Brazil, bringing new elements to the mid-Cretaceous biogeographical, paleogeographical and tectonic reconstructions of western Gondwana.

Palaeoenvironmental significance of organic facies variation across the Lower Toarcian in the northeastern sector of the Lusitanian Basin, Portugal

NASA Astrophysics Data System (ADS)

Rodrigues, Bruno; Duarte, Luís V.; Graciano Mendonça Filho, João; Guilherme Santos, Luiz

2015-04-01

The Pliensbachain - Toarcian is particularly well represented in the Lusitanian Basin (central western Portugal), dominated by benthic and necktonic marl-limestone succession, well dated by ammonites. In this general context, and besides all aspects related to the Toarcian Oceanic Anoxic Event (T-OAE), the Polymorphum (=Tenuicostatum) - Levisoni (= Serpentinum) ammonite zone boundary marks one of the most sedimentological changes occurred in the whole basin (Duarte, 1997). Among all well known available sections for this interval (e.g. Peniche and Rabaçal), the Alcabideque section shows at the base of Levisoni Zone a singular record of brownish marls very poor in macrofauna (the "Chocolate Marls"), unit that is exclusive of northern part of the basin (see Pittet et al., 2014). With the aim to improve the understand about the sedimentary vertical changes occurred between the late Pliensbachian (Emaciatum Zone) and the base of Levisoni Zone, and to clarify the palaeoenvironment of such unit, we developed an organic facies analysis, including palynofacies and organic geochemistry [total organic carbon (TOC), sulfur and biomarkers]. Results confirm that sediments are particularly poor in organic matter, with the highest TOC value reaching 0.41 wt.% around the top of Polymorphum Zone. In the studied succession (around 20 m thick) the organic content is represented mainly by components from palynomorph (essentially sporomorphs) and phytoclast (both opaque and non-opaque) groups (>85%). A strong change occurs at the base of Chocolate Marls, through a clear increase of sporomorphs under the form of tetrads and agglomerates and the lowest occurrence (<2%) of amorphous organic matter, after a peak of this group and marine palynomorphs recorded at the top of Polymorphum Zone. This continental influence occurred at the base of Levisoni Zone is also confirmed by the η-alkanes distribution profile and several biomarkers such as isoprenoides, terpanes and steranes. With these data we emphasize the special sedimentation occurred in the Lusitanian Basin across the T-OAE, clarifying the sedimentary nature and the palaeoenvironmental significance of the "Chocolate Marls", clearly associated with a drop in the sea level. This evidence agrees with the general interpretation presented by previous works about the sedimentary evolution of the whole Lower Toarcian of the western Iberian margin. References Duarte, L. V. 1997. Facies analysis and sequential evolution of the Toarcian-Lower Aalenian series in the Lusitanian Basin (Portugal). Com. Inst. Geol. e Mineiro, 83: 65-94. Pittet, B., Suan, G., Lenoir, F., Duarte, L.V. & Mattioli, E. 2014. Carbon isotope evidence for sedimentary discontinuities in the lower Toarcian of the Lusitanian Basin (Portugal): Sea level change at the onset of the Oceanic Anoxic Event. Sedimentary Geology, 303: 1-14.

Two-dimensional simulation of clastic and carbonate sedimentation, consolidation, subsidence, fluid flow, heat flow and solute transport during the formation of sedimentary basins

NASA Astrophysics Data System (ADS)

Bitzer, Klaus

1999-05-01

Geological processes that create sedimentary basins or act during their formation can be simulated using the public domain computer code `BASIN'. For a given set of geological initial and boundary conditions the sedimentary basin evolution is calculated in a forward modeling approach. The basin is represented in a two-dimensional vertical cross section with individual layers. The stratigraphic, tectonic, hydrodynamic and thermal evolution is calculated beginning at an initial state, and subsequent changes of basin geometry are calculated from sedimentation rates, compaction and pore fluid mobilization, isostatic compensation, fault movement and subsidence. The sedimentologic, hydraulic and thermal parameters are stored at discrete time steps allowing the temporal evolution of the basin to be analyzed. A maximum flexibility in terms of geological conditions is achieved by using individual program modules representing geological processes which can be switched on and off depending on the data available for a specific simulation experiment. The code incorporates a module for clastic and carbonate sedimentation, taking into account the impact of clastic sediment supply on carbonate production. A maximum of four different sediment types, which may be mixed during sedimentation, can be defined. Compaction and fluid flow are coupled through the consolidation equation and the nonlinear form of the equation of state for porosity, allowing nonequilibrium compaction and overpressuring to be calculated. Instead of empirical porosity-effective stress equations, a physically consistent consolidation model is applied which incorporates a porosity dependent sediment compressibility. Transient solute transport and heat flow are calculated as well, applying calculated fluid flow rates from the hydraulic model. As a measure for hydrocarbon generation, the Time-Temperature Index (TTI) is calculated. Three postprocessing programs are available to provide graphic output in PostScript format: BASINVIEW is used to display the distribution of parameters in the simulated cross-section of the basin for defined time steps. It is used in conjunction with the Ghostview software, which is freeware and available on most computer systems. AIBASIN provides PostScript output for Adobe Illustrator®, taking advantage of the layer-concept which facilitates further graphic manipulation. BASELINE is used to display parameter distribution at a defined well or to visualize the temporal evolution of individual elements located in the simulated sedimentary basin. The modular structure of the BASIN code allows additional processes to be included. A module to simulate reactive transport and diagenetic reactions is planned for future versions. The program has been applied to existing sedimentary basins, and it has also shown a high potential for classroom instruction, giving the possibility to create hypothetical basins and to interpret basin evolution in terms of sequence stratigraphy or petroleum potential.

Hot, deep origin of petroleum: deep basin evidence and application

USGS Publications Warehouse

Price, Leigh C.

1978-01-01

Use of the model of a hot deep origin of oil places rigid constraints on the migration and entrapment of crude oil. Specifically, oil originating from depth migrates vertically up faults and is emplaced in traps at shallower depths. Review of petroleum-producing basins worldwide shows oil occurrence in these basins conforms to the restraints of and therefore supports the hypothesis. Most of the world's oil is found in the very deepest sedimentary basins, and production over or adjacent to the deep basin is cut by or directly updip from faults dipping into the basin deep. Generally the greater the fault throw the greater the reserves. Fault-block highs next to deep sedimentary troughs are the best target areas by the present concept. Traps along major basin-forming faults are quite prospective. The structural style of a basin governs the distribution, types, and amounts of hydrocarbons expected and hence the exploration strategy. Production in delta depocenters (Niger) is in structures cut by or updip from major growth faults, and structures not associated with such faults are barren. Production in block fault basins is on horsts next to deep sedimentary troughs (Sirte, North Sea). In basins whose sediment thickness, structure and geologic history are known to a moderate degree, the main oil occurrences can be specifically predicted by analysis of fault systems and possible hydrocarbon migration routes. Use of the concept permits the identification of significant targets which have either been downgraded or ignored in the past, such as production in or just updip from thrust belts, stratigraphic traps over the deep basin associated with major faulting, production over the basin deep, and regional stratigraphic trapping updip from established production along major fault zones.

3D stratigraphic modeling of the Congo turbidite system since 210 ka: an investigation of factors controlling sedimentation

NASA Astrophysics Data System (ADS)

Laurent, Dimitri; Picot, Marie; Marsset, Tania; Droz, Laurence; Rabineau, Marina; Granjeon, Didier; Molliex, Stéphane

2017-04-01

The geometry and internal functioning of turbidite systems are relatively well-constrained today. However, the respective role of autogenic (topographic compensation, dynamics of turbidity currents…) and allogenic factors (tectonics, sea-level, climate) governing their architectural evolution is still under debate. The geometry of the Quaternary Congo Fan is characterized by successive sedimentary prograding/retrograding cycles bounded by upfan avulsions, reflecting a periodic control of sedimentation (Picot et al., 2016). Multi-proxy studies revealed a strong interplay between autogenic control and climate forcing as evidenced by changes in fluvial sediment supplies consistent with arid and humid periods in the Congo River Basin. In the light of these results, the aim of this study is to investigate the relative impact of internal and external forcing factors controlling, both in time and space, the formation and evolution of depocenters of the Congo Deep-Sea Fan since 210 ka. This work represents the first attempt to model in 3D the stratigraphic architecture of the Congo turbidite system using DionisosFlow (IFP-EN), a diffusion process-based software. It allows the simulation of sediment transport and the 3D geometry reproduction of sedimentary units based on physical processes such as sea level changes, tectonics, sediment supply and transport. According to the modeling results, the role of topographic compensation in the deep-sea fan geometry is secondary compared to climate changes in the drainage basin. It appears that a periodic variation of sediment discharge and water flow is necessary to simulate the timing and volume of prograding/retrograding sedimentary cycles and more particularly the upfan avulsion events. The best-fit simulations show that the overriding factor for such changes corresponds to the expansion of the vegetation cover in the catchment basin associated to the Milankovitch cycle of precession which controlled the West African Monsoon intensity. These external forcing factors are responsible for the evolution of the capacity of turbidity currents by directly acting on the river runoff magnitude and the sediment budget according to the balance between mechanical and chemical erosion. If the sediment supply is the key parameter for the large scale sedimentary cycles, a steep increase of the sand/mud ratio leads to the development of sub-cycles characterized by middle fan avulsions. We identified these events as related to abrupt destabilizations of river mouth bars linked to periodic Congo River floods. Finally, the local slope gradient only plays a role in the maximal length of the turbidity currents and deposition in the most distal part of the basin. To conclude, the stratigraphic modeling allows us to propose an evolutionary "source to sink" model of the Quaternary Congo Fan, emphasizing the interconnection through time between drainage basin responses to climate change and sedimentary transfers in the deep-water environment. Picot, M. et al., 2016. Controls on turbidite sedimentation: Insights from a quantitative approach of submarine channel and lobe architecture (Late Quaternary Congo Fan). Marine and Petroleum Geology, 72, 423-446. Keywords: Congo, sedimentary basin, Quaternary, turbidite system, sedimentary cycles, geophysical data, stratigraphic modeling, DionisosFlow

Ground-water hydrology of the Willamette basin, Oregon

USGS Publications Warehouse

Conlon, Terrence D.; Wozniak, Karl C.; Woodcock, Douglas; Herrera, Nora B.; Fisher, Bruce J.; Morgan, David S.; Lee, Karl K.; Hinkle, Stephen R.

2005-01-01

The Willamette Basin encompasses a drainage of 12,000 square miles and is home to approximately 70 percent of Oregon's population. Agriculture and population are concentrated in the lowland, a broad, relatively flat area between the Coast and Cascade Ranges. Annual rainfall is high, with about 80 percent of precipitation falling from October through March and less than 5 percent falling in July and August, the peak growing season. Population growth and an increase in cultivation of crops needing irrigation have produced a growing seasonal demand for water. Because many streams are administratively closed to new appropriations in summer, ground water is the most likely source for meeting future water demand. This report describes the current understanding of the regional ground-water flow system, and addresses the effects of ground-water development. This study defines seven regional hydrogeologic units in the Willamette Basin. The highly permeable High Cascade unit consists of young volcanic material found at the surface along the crest of the Cascade Range. Four sedimentary hydrogeologic units fill the lowland between the Cascade and Coast Ranges. Young, highly permeable coarse-grained sediments of the upper sedimentary unit have a limited extent in the floodplains of the major streams and in part of the Portland Basin. Extending over much of the lowland where the upper sedimentary unit does not occur, silts and clays of the Willamette silt unit act as a confining unit. The middle sedimentary unit, consisting of permeable coarse-grained material, occurs beneath the Willamette silt and upper sedimentary units and at the surface as terraces in the lowland. Beneath these units is the lower sedimentary unit, which consists of predominantly fine-grained sediments. In the northern part of the basin, lavas of the Columbia River basalt unit occur at the surface in uplands and beneath the basin-fill sedimentary units. The Columbia River basalt unit contains multiple productive water-bearing zones. A basement confining unit of older marine and volcanic rocks of low permeability underlies the basin and occurs at land surface in the Coast Range and western part of the Cascade Range. Most recharge in the basin is from infiltration of precipitation, and the spatial distribution of recharge mimics the distribution of precipitation, which increases with elevation. Basinwide annual mean recharge is estimated to be 22 inches. Rain and snowmelt easily recharge into the permeable High Cascade unit and discharge within the High Cascade area. Most recharge in the Coast Range and western part of the Cascade Range follows short flowpaths through the upper part of the low permeability material and discharges to streams within the mountains. Consequently, recharge in the Coast and Ranges is not available as lateral ground-water flow into the lowland, where most ground-water use occurs. Within the lowland, annual mean recharge is 16 inches and most recharge occurs from November to April, when rainfall is large and evapotranspiration is small. From May to October recharge is negligible because precipitation is small and evapotranspiration is large. Discharge of ground water is mainly to streams. Ground-water discharge is a relatively large component of flow in streams that drain the High Cascade unit and parts of the Portland Basin where permeable units are at the surface. In streams that do not head in the High Cascade area, streamflow is generally dominated by runoff of precipitation. Ground-water in the permeable units in the lowland discharges to the major streams where there is a good hydraulic connection between aquifers and streams. Ground-water discharge to smaller streams, which flow on the less permeable Willamette silt unit, is small and mostly from the Willamette silt unit. Most ground-water withdrawals occur within the lowland. Irrigation is the largest use of ground water, accounting for 240,000 acre feet of withdrawals, or 81 p

Using hydrogeologic data to evaluate geothermal potential in the eastern Great Basin

USGS Publications Warehouse

Masbruch, Melissa D.; Heilweil, Victor M.; Brooks, Lynette E.

2012-01-01

In support of a larger study to evaluate geothermal resource development of high-permeability stratigraphic units in sedimentary basins, this paper integrates groundwater and thermal data to evaluate heat and fluid flow within the eastern Great Basin. Previously published information from a hydrogeologic framework, a potentiometric-surface map, and groundwater budgets was compared to a surficial heat-flow map. Comparisons between regional groundwater flow patterns and surficial heat flow indicate a strong spatial relation between regional groundwater movement and surficial heat distribution. Combining aquifer geometry and heat-flow maps, a selected group of subareas within the eastern Great Basin are identified that have high surficial heat flow and are underlain by a sequence of thick basin-fill deposits and permeable carbonate aquifers. These regions may have potential for future geothermal resources development.

Seismic stratigraphy of sedimentary cover in Amerasian Basin based on the results of Russian High Arctic expeditions

NASA Astrophysics Data System (ADS)

Poselov, Viktor; Kireev, Artem; Smirnov, Oleg; Butsenko, Viktor; Zholondz, Sergey; Savin, Vasily

2016-04-01

Massive amount of multichannel seismic (MCS) data were obtained by Russian High Arct ic expeditions "Arctica-2011", "Acrtica-2012" and "Arctica-2014". More than 40 MCS lines are located in the Amerasian basin and help to substantiate the seismic stratigraphy model of its sedimentary cover. The proposed seismic stratigraphy model was successively determined for the Cenozoic and pre-Cenozoic parts of the sedimentary section and was based on correlation of the Russian MCS data and seismic data documented by boreholes. Cenozoic part of the sedimentary cover is based on correlation of the Russian MCS data and AWI91090 section calibrated by ACEX-2004 boreholes on the Lomonosov Ridge. Two major unconformities are traced. The upper regional unconformity (RU) is associated with a major pre-Miocene hiatus. Another major hiatus is recorded in the borehole section between the Campanian and the Upper Paleocene units. It is recognized as the post-Campanian unconformity (pCU) in the seismic sections. Formation of the regional unconformities is associated with a fundamental change in depositional environment. Formation of RU was initiated by opening of the Fram Strait gateway at the Paleogene/Neogene boundary. Post-Campanian unconformity is linked with the initial stage of the Eurasian Basin opening between the Cretaceous and the Paleogene. Cenozoic sedimentary units are continuously traced from the East-Siberian and Chukchi sea shelves across the transit zone to the Amerasian basin. Paleogene unit (between pCU and RU) is formed under the neritic depositional environment and it is characterized by an extremely small thickness on the Lomonosov Ridge (less than 200 m), on the Mendeleev Rise and in the Podvodnikov Basin (not more than 300-400 m). Neogene unit (above RU) consists of hemipelagic deposits and occupies the essential part of thickness of the Cenozoic section in Podvodnikov and Makarov Basins. Interval velocities in the Paleogene unit vary within 2.8-3.2 km/s, in the Neogene unit they vary within 1.8-2.7 km/s. Pre-Cenozoic part of the sedimentary cover is based on tracing major unconformities from boreholes on the Chukchi shelf (Crackerjack, Klondike, Popcorn) to the North-Chuckchi Trough and further to the Mendeleev Rise as well as to the Vilkitsky Trough and the adjacent Podvodnikov Basin. Three regional unconformities are correlated: Jurassic (JU - top of the Upper Ellesmerian unit), Lower Cretaceous (LCU) and Brookian (BU - base of the Lower Brookian unit). Above the acoustic basement the pre-Cenozoic section is mainly represented by terrigenous units. Two major unconformities: RU and pCU are allocated on all MCS lines intersecting the Mendeleev Rise along its entire extent. BU is traced nearly everywhere along the rise excepting certain acoustic basement highs. All unconformities are also traced from the Mendeleev Rise to the continental structure of the Chuckchi Borderland. Sedimentary sequence between pCU and JU which underlies deposits of the Upper Ellesmerian unit is recorded as a synrift unit of the entire area of the Podvodnikov Basin. MCS data show a natural prolongation of the sedimentary cover from the shelf to the Podvodnikov Basin without any breaks and tectonic movements. Interval velocities in the Upper Cretaceous unit (between pCU and BU) vary within 3.2-3.9 km/s, in the pre-Upper Cretaceous units (between BU and the acoustic basement) vary within 4.1-4.8 km/s.

Mineralogy of selected sedimentary interbeds at or near the Idaho National Engineering Laboratory, Idaho

USGS Publications Warehouse

Reed, Michael F.; Bartholomay, Roy C.

1994-01-01

The U.S. Geological Survey (USGS) Project Office at the Idaho National Engineering Laboratory (INEL), in cooperation with the U.S. Department of Energy and Idaho State University, analyzed 66 samples from sedimentary interbed cores during a 38-month period beginning in October 1990 to determine bulk and clay mineralogy. These cores had been collected from 19 sites in the Big Lost River Basin, 2 sites in the Birch Creek Basin, and 1 site in the Mud Lake Basin, and were archived at the USGS lithologic core library at the INEL. Mineralogy data indicate that the core samples from the Big Lost River Basin have larger mean and median percentages of quartz, total feldspar, and total clay minerals, but smaller mean and median percentages of calcite than the core samples from the Birch Creek Basin. Core samples from the Mud Lake Basin have abundant quartz, total feldspar, calcite, and total clay minerals.

Site Effect Analysis in the Izmit Basin of Turkey: Preliminary Results from the Wave Propagation Simulation using the Spectral Element Method

NASA Astrophysics Data System (ADS)

Firtana Elcomert, Karolin; Kocaoglu, Argun

2014-05-01

Sedimentary basins affect the propagation characteristics of the seismic waves and cause significant ground motion amplification during an earthquake. While the impedance contrast between the sedimentary layer and bedrock predominantly controls the resonance frequencies and their amplitudes (seismic amplification), surface waves generated within the basin, make the waveforms more complex and longer in duration. When a dense network of weak and/or strong motion sensors is available, site effect or more specifically sedimentary basin amplification can be directly estimated experimentally provided that significant earthquakes occur during the period of study. Alternatively, site effect can be investigated through simulation of ground motion. The objective of this study is to investigate the 2-D site effect in the Izmit Basin located in the eastern Marmara region of Turkey, using the currently available bedrock topography and shear-wave velocity data. The Izmit Basin was formed in Plio-Quaternary period and is known to be a pull-apart basin controlled by the northern branch of the North Anatolian Fault Zone (Şengör et al. 2005). A thorough analysis of seismic hazard is important since the city of Izmit and its metropolitan area is located in this region. Using a spectral element code, SPECFEM2D (Komatitsch et al. 1998), this work presents some of the preliminary results of the 2-D seismic wave propagation simulations for the Izmit basin. The spectral-element method allows accurate and efficient simulation of seismic wave propagation due to its advantages over the other numerical modeling techniques by means of representation of the wavefield and the computational mesh. The preliminary results of this study suggest that seismic wave propagation simulations give some insight into the site amplification phenomena in the Izmit basin. Comparison of seismograms recorded on the top of sedimentary layer with those recorded on the bedrock show more complex waveforms with higher amplitudes on seismograms recorded at the free surface. Furthermore, modeling reveals that observed seismograms include surface waves whose excitation is clearly related to the basin geometry.

Evidence of the Zanclean megaflood in the eastern Mediterranean Basin.

PubMed

Micallef, Aaron; Camerlenghi, Angelo; Garcia-Castellanos, Daniel; Cunarro Otero, Daniel; Gutscher, Marc-André; Barreca, Giovanni; Spatola, Daniele; Facchin, Lorenzo; Geletti, Riccardo; Krastel, Sebastian; Gross, Felix; Urlaub, Morelia

2018-01-18

The Messinian salinity crisis (MSC) - the most abrupt, global-scale environmental change since the end of the Cretaceous - is widely associated with partial desiccation of the Mediterranean Sea. A major open question is the way normal marine conditions were abruptly restored at the end of the MSC. Here we use geological and geophysical data to identify an extensive, buried and chaotic sedimentary body deposited in the western Ionian Basin after the massive Messinian salts and before the Plio-Quaternary open-marine sedimentary sequence. We show that this body is consistent with the passage of a megaflood from the western to the eastern Mediterranean Sea via a south-eastern Sicilian gateway. Our findings provide evidence for a large amplitude drawdown in the Ionian Basin during the MSC, support the scenario of a Mediterranean-wide catastrophic flood at the end of the MSC, and suggest that the identified sedimentary body is the largest known megaflood deposit on Earth.

Is There any Relationship Between the Santa Elena Depression and Chicxulub Impact Crater, Northwestern Yucatan Peninsula, Mexico?

NASA Astrophysics Data System (ADS)

Lefticariu, L.

2005-05-01

The Terminal Cretaceous Chicxulub Impact Crater had a strong control on the depositional and diagenetic history of the northern Yucatan Platform during most of the Cenozoic Era. The Chicxulub Sedimentary Basin (henceforth Basin), which approximately coincides with the impact crater, is circumscribed by a concentration of karstic sinkholes known as the Ring of Cenotes. Santa Elena Depression (henceforth Depression) is the name proposed for the bowl-shaped buried feature, first contoured by geophysical studies, immediately south of the Basin, in the area where the Ticul 1 and UNAM 5 wells were drilled. Lithologic, petrographic, and biostratigraphic data on PEMEX, UNAM, and ICDP cores show that: 1) Cenozoic deposits are much thicker inside the Basin than inside the Depression, 2) in general, the Cenozoic formations from inside the Depression are the thickest among those outside the Basin, 3) variably dolomitized pelagic or outer-platform wackestone or mudstone occur both inside the Basin and Depression, 4) the age of the deeper-water sedimentary carbonate rocks is Paleocene-Eocene inside the Basin and Paleocene?-Early Eocene inside the Depression, 5) the oldest formations that crop out are of Middle Eocene age at the edge of the Basin and Early-Middle Eocene age inside the Depression, 6) saline lake deposits, that consist chiefly of anhydrite, gypsum, and fine carbonate, and also contain quartz, chert, clay, zeolite, potassium feldspar, pyrite, and fragments of wood, are present in the Cenozoic section of the UNAM 5 core between 282 and 198 m below the present land surface, 7) the dolomite, subaerial exposure features (subaerial crusts, vugs, karst, dedolomite), and vug-filling cement from the Eocene formations are more abundant inside the Depression than inside the Basin. The depositional environments that are proposed for explaining the Cenozoic facies succession within the Santa Elena Depression are: 1) deeper marine water (Paleocene?-Early Eocene), 2) relatively isolated saline lake (Middle Eocene), and 3) shallow marine water (Middle-Late Eocene?). In places, the deeper-water facies are similar to those within the Chicxulub Sedimentary Basin. The shallow-water facies is similar to those occurring outside the Basin. In general, quartz and silicates are rare in the Cenozoic sedimentary carbonate of the northwestern Yucatan Peninsula. Therefore, their presence in the UNAM 5 core could be attributed to either impact breccia reworking or silicic volcanic processes. Quartz, chert, zeolite, and clay also are common in the suevite breccia of both Yax-1 and UNAM 5 cores. The fact that the Santa Elena Depression was a distinct sedimentary basin during much of the Paleogene could be explained by any or a combination of the following hypotheses: 1) In spite of being located outside the cenote ring, the Depression is a sub-basin of the larger and deeper Chicxulub Sedimentary Basin and is therefore located within the Chicxulub Impact Crater, 2) the Depression coincides with an impact crater distinct from the Chicxulub Impact Crater, 3) the Depression formed after the Chicxulub bolide impact due to slumping, crater wall failure, or larger-scale tectonic processes. The lack of conclusive evidence for multiple impact breccia layers in the northwestern Yucatan Peninsula, corroborated with the presence on top of the impact breccia from UNAM 5 core of deeper-water limestone similar to that of Late Paleocene-Early Eocene age from Yax-1 core, would be more consistent with either the first or third hypothesis.

Giant fields of the late 80s associated with type [open quotes]A[close quotes] subduction in South America

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duval, B.; Cramez, C.; Figuera, J.

1993-02-01

About 10 billion bbl of recoverable oil have been found in these three fields for which the petroleum generating subsystem is very similar. The potential source rocks are the organic sediments associated with the major downlap surface of the post-Pangea continental encroachment sedimentary cycle, i.e., MFS 91, 5 Ma (La Luna formation). However, the concentrating physico-chemical petroleum subsystem is quite different. The El Furrial/Musipan field is associated with a Tertiary foredeep basin overlying a generating Atlantic type passive margin. On the other hand, Cusiana and Ceuta fields are associated with a Tertiary foredeep basin developed over a generating back-arc basin.more » The different stacking of sedimentary basins controls the migration/entrapment petroleum subsystem. In El Furrial/Musipan, decollement surfaces and their associated thrusts are predominant whereas, in Ceuta and Cusiana the majority of compressional structures are created by tectonic inversions. These tectonic settings create different petroleum systems: (a) supercharged with low impedance and lateral drainage in El Furrial/Musipan, (b) normally charged with high impedance and vertically drained in Ceuta and Cusiana area. Each case requires appropriated exploration approaches.« less

Sedimentology of the lower Karoo Supergroup fluvial strata in the Tuli Basin, South Africa

NASA Astrophysics Data System (ADS)

Bordy, Emese M.; Catuneanu, Octavian

2002-11-01

The Karoo Supergroup in the Tuli Basin (South Africa) consists of a sedimentary sequence (˜450-500 m) composed of four stratigraphic units, namely the informal Basal, Middle and Upper Units, and the formal Clarens Formation. The units were deposited in continental settings from approximately Late Carboniferous to Middle Jurassic. This paper focuses on the ˜60-m-thick Basal Unit, which was examined in terms of sedimentary facies and palaeo-environments based on evidence provided by primary sedimentary structures, palaeo-flow measurements, palaeontological findings, borehole data (59 core descriptions) and stratigraphic relations. Three main facies associations have been identified: (i) gravelstone (breccias and conglomerate-breccias), (ii) sandstone and (iii) fine-grained sedimentary rocks. The coarser facies are interpreted as colluvial fan deposits, possibly associated with glaciogenic diamictites. The sandstone facies association is mainly attributed to channel fills of low sinuosity, braided fluvial systems. The coal-bearing finer-grained facies are interpreted as overbank and thaw-lake deposits, and represent the lower energy correlatives of the sandy channel fills. Sediment aggradation in this fluvio-lacustrine system took place under cold climatic conditions, with floating lake ice likely associated with lacustrine environments. Palaeo-current indicators suggest that the highly weathered, quartz-vein-rich metamorphic rock source of the Basal Unit was situated east-northeast of the study area. The accumulation of the Basal Unit took place within the back-bulge depozone of the Karoo foreland system. In addition to flexural subsidence, the amount of accommodation in this tectonic setting was also possibly modified by extensional tectonism in the later stages of the basin development. Based on sedimentological and biostratigraphic evidence, the coal-bearing fine-grained facies association displays strong similarities with the Vryheid Formation of the main Karoo Basin to the south. The lowermost non-fossiliferous breccias have been correlated before with the Dwyka Group in the main Karoo, and hence the Basal Unit may be regarded as the distal equivalent of the Dwyka and Ecca groups to the south.

Provenance and detrital zircon geochronologic evolution of lower Brookian foreland basin deposits of the western Brooks Range, Alaska, and implications for early Brookian tectonism

USGS Publications Warehouse

Moore, Thomas; O'Sullivan, Paul B.; Potter, Christopher J.; Donelick, Raymond A.

2015-01-01

The Upper Jurassic and Lower Cretaceous part of the Brookian sequence of northern Alaska consists of syntectonic deposits shed from the north-directed, early Brookian orogenic belt. We employ sandstone petrography, detrital zircon U-Pb age analysis, and zircon fission-track double-dating methods to investigate these deposits in a succession of thin regional thrust sheets in the western Brooks Range and in the adjacent Colville foreland basin to determine sediment provenance, sedimentary dispersal patterns, and to reconstruct the evolution of the Brookian orogen. The oldest and structurally highest deposits are allochthonous Upper Jurassic volcanic arc–derived sandstones that rest on accreted ophiolitic and/or subduction assemblage mafic igneous rocks. These strata contain a nearly unimodal Late Jurassic zircon population and are interpreted to be a fragment of a forearc basin that was emplaced onto the Brooks Range during arc-continent collision. Synorogenic deposits found at structurally lower levels contain decreasing amounts of ophiolite and arc debris, Jurassic zircons, and increasing amounts of continentally derived sedimentary detritus accompanied by broadly distributed late Paleozoic and Triassic (359–200 Ma), early Paleozoic (542–359 Ma), and Paleoproterozoic (2000–1750 Ma) zircon populations. The zircon populations display fission-track evidence of cooling during the Brookian event and evidence of an earlier episode of cooling in the late Paleozoic and Triassic. Surprisingly, there is little evidence for erosion of the continental basement of Arctic Alaska, its Paleozoic sedimentary cover, or its hinterland metamorphic rocks in early foreland basin strata at any structural and/or stratigraphic level in the western Brooks Range. Detritus from exhumation of these sources did not arrive in the foreland basin until the middle or late Albian in the central part of the Colville Basin.These observations indicate that two primary provenance areas provided detritus to the early Brookian foreland basin of the western Brooks Range: (1) local sources in the oceanic Angayucham terrane, which forms the upper plate of the orogen, and (2) a sedimentary source region outside of northern Alaska. Pre-Jurassic zircons and continental grain types suggest the latter detritus was derived from a thick succession of Triassic turbidites in the Russian Far East that were originally shed from source areas in the Uralian-Taimyr orogen and deposited in the South Anyui Ocean, interpreted here as an early Mesozoic remnant basin. Structural thickening and northward emplacement onto the continental margin of Chukotka during the Brookian structural event are proposed to have led to development of a highland source area located in eastern Chukotka, Wrangel Island, and Herald Arch region. The abundance of detritus from this source area in most of the samples argues that the Colville Basin and ancestral foreland basins were supplied by longitudinal sediment dispersal systems that extended eastward along the Brooks Range orogen and were tectonically recycled into the active foredeep as the thrust front propagated toward the foreland. Movement of clastic sedimentary material from eastern Chukotka, Wrangel Island, and Herald Arch into Brookian foreland basins in northern Alaska confirms the interpretations of previous workers that the Brookian deformational belt extends into the Russian Far East and demonstrates that the Arctic Alaska–Chukotka microplate was a unified geologic entity by the Early Cretaceous.

Palynostratigraphy of the Erkovtsy field of brown coal (the Zeya-Bureya sedimentary basin)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kezina, T.V.; Litvinenko, N.D.

2007-08-15

The Erkovtsy brown coal field in the northwestern Zeya-Bureya sedimentary basin (129-130{sup o}E, 46-47{sup o}N) is structurally confined to southern flank of the Mesozoic-Cenozoic Belogor'e depression. The verified stratigraphic scheme of the coalfield sedimentary sequence is substantiated by palynological data on core samples from 18 boreholes sampled in the course of detailed prospecting and by paleobotanical analysis of sections in the Yuzhnyi sector of the coalfield (data of 1998 by M.A. Akhmetiev and S.P. Manchester). Sections of the Erkovtsy, Arkhara-Boguchan, and Raichikha brown-coal mines are correlated. Stratigraphic subdivisions distinguished in the studied sedimentary succession are the middle and upper Tsagayanmore » subformations (the latter incorporating the Kivda Beds), Raichikha, Mukhino, Buzuli, and Sazanka formations.« less

Early Triassic environmental dynamics and microbial development during the Smithian-Spathian transition (Lower Weber Canyon, Utah, USA)

NASA Astrophysics Data System (ADS)

Grosjean, Anne-Sabine; Vennin, Emmanuelle; Olivier, Nicolas; Caravaca, Gwénaël; Thomazo, Christophe; Fara, Emmanuel; Escarguel, Gilles; Bylund, Kevin G.; Jenks, James F.; Stephen, Daniel A.; Brayard, Arnaud

2018-01-01

The Early Triassic biotic recovery following the end-Permian mass extinction is well documented in the Smithian-Spathian Thaynes Group of the western USA basin. This sedimentary succession is commonly interpreted as recording harsh conditions of various shallow marine environments where microbial structures flourished. However, recent studies questioned the relevance of the classical view of long-lasting deleterious post-crisis conditions and suggested a rapid diversification of some marine ecosystems during the Early Triassic. Using field and microfacies analyses, we investigate a well-preserved Early Triassic marine sedimentary succession in Lower Weber Canyon (Utah, USA). The identification of microbial structures and their depositional settings provide insights on factors controlling their morphologies and distribution. The Lower Weber Canyon sediments record the vertical evolution of depositional environments from a middle Smithian microbial and dolosiliciclastic peritidal system to a late Smithian-early Spathian bioclastic, muddy mid ramp. The microbial deposits are interpreted as Microbially Induced Sedimentary Structures (MISS) that developed either (1) in a subtidal mid ramp where microbial wrinkles and chips are associated with megaripples characterizing hydrodynamic conditions of lower flow regime, or (2) in protected areas of inter- to subtidal inner ramp where they formed laminae and domal structures. Integrated with other published data, our investigations highlight that the distribution of these microbial structures was influenced by the combined effects of bathymetry, hydrodynamic conditions, lithology of the substrat physico-chemical characteristics of the depositional environment and by the regional relative sea-level fluctuations. Thus, we suggest that local environmental factors and basin dynamics primarily controlled the modalities of microbial development and preservation during the Early Triassic in the western USA basin.

Coseismic and blind fault of the 2015 Pishan Mw 6.5 earthquake: Implications for the sedimentary-tectonic framework of the western Kunlun Mountains, northern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Lu, Renqi; Xu, Xiwei; He, Dengfa; Liu, Bo; Tan, Xibin; Wang, Xiaoshan

2016-04-01

On 3 July 2015, the Mw 6.5 Pishan earthquake occurred in the western Kunlun Mountains front, at the northern margin of the Tibetan Plateau. To reveal the sedimentary-tectonic framework of the seismically active structure, three high-resolution seismic reflection profiles and well drilling data were collected for seismic interpretation. The western Kunlun Mountains and Tarim Basin have two gypseous detachments and one basement detachment that control the tectonic framework and structural deformation. The upper gypseous detachment (D1) is in the lower Paleocene, and the middle gypseous detachment (D2) is in the Middle to Lower Cambrian. A Neogene shallow thrust system is developing above D1 and includes the Zepu fault (F2) and Mazar Tagh fault (F3). A deep thrust system is developing between D1 and D2 and forms a large-scale structural wedge beneath the western Kunlun Mountains front. The Pishan Mw 6.5 earthquake was triggered on a frontal blind fault of this deep thrust system. The lower detachment is in the Proterozoic basement (D3), which extends into the Tarim Basin and develops another deep thrust (F4) beneath the F3 belt. D1, D2, D3, and the Tiekelike fault (F1) merge together at depth. Crustal shortening of the western Kunlun Mountains front continues for approximately 54 km. Two tectonic evolutionary stages have occurred since the Miocene according to sedimentary unconformity, axial analysis, and fault interpretation. The results of this study indicate a regime of episodic growth of the western Kunlun Mountains and Tarim Basin during the Cenozoic.

Uncertainty quantification of overpressure buildup through inverse modeling of compaction processes in sedimentary basins

NASA Astrophysics Data System (ADS)

Colombo, Ivo; Porta, Giovanni M.; Ruffo, Paolo; Guadagnini, Alberto

2017-03-01

This study illustrates a procedure conducive to a preliminary risk analysis of overpressure development in sedimentary basins characterized by alternating depositional events of sandstone and shale layers. The approach rests on two key elements: (1) forward modeling of fluid flow and compaction, and (2) application of a model-complexity reduction technique based on a generalized polynomial chaos expansion (gPCE). The forward model considers a one-dimensional vertical compaction processes. The gPCE model is then used in an inverse modeling context to obtain efficient model parameter estimation and uncertainty quantification. The methodology is applied to two field settings considered in previous literature works, i.e. the Venture Field (Scotian Shelf, Canada) and the Navarin Basin (Bering Sea, Alaska, USA), relying on available porosity and pressure information for model calibration. It is found that the best result is obtained when porosity and pressure data are considered jointly in the model calibration procedure. Uncertainty propagation from unknown input parameters to model outputs, such as pore pressure vertical distribution, is investigated and quantified. This modeling strategy enables one to quantify the relative importance of key phenomena governing the feedback between sediment compaction and fluid flow processes and driving the buildup of fluid overpressure in stratified sedimentary basins characterized by the presence of low-permeability layers. The results here illustrated (1) allow for diagnosis of the critical role played by the parameters of quantitative formulations linking porosity and permeability in compacted shales and (2) provide an explicit and detailed quantification of the effects of their uncertainty in field settings.

Inversion of the Erlian Basin (NE China) in the early Late Cretaceous: Implications for the collision of the Okhotomorsk Block with East Asia

NASA Astrophysics Data System (ADS)

Guo, Zhi-Xin; Shi, Yuan-Peng; Yang, Yong-Tai; Jiang, Shuan-Qi; Li, Lin-Bo; Zhao, Zhi-Gang

2018-04-01

A significant transition in tectonic regime from extension to compression occurred throughout East Asia during the mid-Cretaceous and has stimulated much attention. However, the timing and driving mechanisms of the transition remain disputed. The Erlian Basin, a giant late Mesozoic intracontinental petroliferous basin located in the Inner Mongolia, Northeast China, contains important sedimentary and structural records related to the mid-Cretaceous compressional event. The stratigraphical, sedimentological and structural analyses reveal that a NW-SE compressional inversion occurred in the Erlian Basin between the depositions of the Lower Cretaceous Saihan and Upper Cretaceous Erlian formations, causing intense folding of the Saihan Formation and underlying strata, and the northwestward migration of the depocenters of the Erlian Formation. Based on the newly obtained detrital zircon U-Pb data and previously published paleomagnetism- and fossil-based ages, the Saihan and Erlian formations are suggested as latest Aptian-Albian and post-early Cenomanian in age, respectively, implying that the inversion in the Erlian Basin occurred in the early Late Cretaceous (Cenomanian time). Apatite fission-track thermochronological data record an early Late Cretaceous cooling/exhuming event in the basin, corresponding well with the aforementioned sedimentary, structural and chronological analyses. Combining with the tectono-sedimentary evolutions of the neighboring basins of the Erlian Basin, we suggest that the early Late Cretaceous inversional event in the Erlian Basin and the large scale tectonic transition in East Asia shared the common driving mechanism, probably resulting from the Okhotomorsk Block-East Asia collisional event at about 100-89 Ma.

Transient hydrodynamics within intercratonic sedimentary basins during glacial cycles

NASA Astrophysics Data System (ADS)

Bense, V. F.; Person, M. A.

2008-12-01

The hydrodynamic consequences of a glaciation/deglaciation cycle within an intercratonic sedimentary basin on subsurface transport processes is assessed using numerical models. In our analysis we consider the effects of mechanical ice sheet loading, permafrost formation, variable density fluids, and lithospheric flexure on solute/isotope transport, groundwater residence times, and transient hydraulic head distributions. The simulations are intended to apply, in a generic sense, to intercratonic sedimentary basins that would have been near the southern limit of the Laurentide Ice Sheet during the last glacial maximum (˜20 ka B.P.), such as the Williston, Michigan, and Illinois basins. We show that in such basins fluid flow and recharge rates are strongly elevated during glaciation as compared to nonglacial periods. Furthermore, our results illustrate that steady state hydrodynamic conditions in these basins are probably never reached during a 32.5 ka cycle of advance and retreat of a wet-based ice sheet. Present-day hydrogeological conditions across formerly glaciated areas are likely to still reflect the impact of the last glaciation and associated processes that ended locally more than 10 ka B.P. Our results reveal characteristic spatial patterns of underpressure and overpressure that occur in aquitards and aquifers, respectively, as a result of recent glaciation. The calculated emplacement of low salinity, isotopically light glacial meltwater along basin margins is roughly consistent with observations from formerly glaciated basins in North America. The modeling presented in this study will help to improve the management of groundwater resources in formerly glaciated basins as well as to evaluate the viability on geological timescales of nuclear waste repositories located at high latitudes.

Unravelling the stratigraphy and sedimentation history of the uppermost Cretaceous to Eocene sediments of the Kuching Zone in West Sarawak (Malaysia), Borneo

NASA Astrophysics Data System (ADS)

Breitfeld, H. Tim; Hall, Robert; Galin, Thomson; BouDagher-Fadel, Marcelle K.

2018-07-01

The Kuching Zone in West Sarawak consists of two different sedimentary basins, the Kayan and Ketungau Basins. The sedimentary successions in the basins are part of the Kuching Supergroup that extends into Kalimantan. The uppermost Cretaceous (Maastrichtian) to Lower Eocene Kayan Group forms the sedimentary deposits directly above a major unconformity, the Pedawan Unconformity, which marks the cessation of subduction-related magmatism beneath SW Borneo and the Schwaner Mountains, due to termination of the Paleo-Pacific subduction. The successions consist of the Kayan and Penrissen Sandstones and are dominated by fluvial channels, alluvial fans and floodplain deposits with some deltaic to tidally-influenced sections in the Kayan Sandstone. In the late Early or early Middle Eocene, sedimentation in this basin ceased and a new basin, the Ketungau Basin, developed to the east. This change is marked by the Kayan Unconformity. Sedimentation resumed in the Middle Eocene (Lutetian) with the marginal marine, tidal to deltaic Ngili Sandstone and Silantek Formation. Upsequence, the Silantek Formation is dominated by floodplain and subsidiary fluvial deposits. The Bako-Mintu Sandstone, a potential lateral equivalent of the Silantek Formation, is formed of major fluvial channels. The top of the Ketungau Group in West Sarawak is formed by the fluvially-dominated Tutoop Sandstone. This shows a transition of the Ketungau Group in time towards terrestrial/fluvially-dominated deposits. Paleocurrent measurements show river systems were complex, but reveal a dominant southern source. This suggests uplift of southern Borneo initiated in the region of the present-day Schwaner Mountains from the latest Cretaceous onwards. Additional sources were local sources in the West Borneo province, Mesozoic melanges to the east and potentially the Malay Peninsula. The Ketungau Group also includes reworked deposits of the Kayan Group. The sediments of the Kuching Supergroup are predominantly horizontal or dip with low angles and form large open synclines. Steep dips are usually restricted to faults, such as the Lupar Line.

Simulation of groundwater flow and the interaction of groundwater and surface water in the Willamette Basin and Central Willamette subbasin, Oregon

USGS Publications Warehouse

Herrera, Nora B.; Burns, Erick R.; Conlon, Terrence D.

2014-01-01

Full appropriation of tributary streamflow during summer, a growing population, and agricultural needs are increasing the demand for groundwater in the Willamette Basin. Greater groundwater use could diminish streamflow and create seasonal and long-term declines in groundwater levels. The U.S. Geological Survey (USGS) and the Oregon Water Resources Department (OWRD) cooperated in a study to develop a conceptual and quantitative understanding of the groundwater-flow system of the Willamette Basin with an emphasis on the Central Willamette subbasin. This final report from the cooperative study describes numerical models of the regional and local groundwater-flow systems and evaluates the effects of pumping on groundwater and surface‑water resources. The models described in this report can be used to evaluate spatial and temporal effects of pumping on groundwater, base flow, and stream capture. The regional model covers about 6,700 square miles of the 12,000-square mile Willamette and Sandy River drainage basins in northwestern Oregon—referred to as the Willamette Basin in this report. The Willamette Basin is a topographic and structural trough that lies between the Coast Range and the Cascade Range and is divided into five sedimentary subbasins underlain and separated by basalts of the Columbia River Basalt Group (Columbia River basalt) that crop out as local uplands. From north to south, these five subbasins are the Portland subbasin, the Tualatin subbasin, the Central Willamette subbasin, the Stayton subbasin, and the Southern Willamette subbasin. Recharge in the Willamette Basin is primarily from precipitation in the uplands of the Cascade Range, Coast Range, and western Cascades areas. Groundwater moves downward and laterally through sedimentary or basalt units until it discharges locally to wells, evapotranspiration, or streams. Mean annual groundwater withdrawal for water years 1995 and 1996 was about 400 cubic feet per second; irrigation withdrawals accounted for about 80 percent of that total. The upper 180 feet of productive aquifers in the Central Willamette and Southern Willamette subbasins produced about 70 percent of the total pumped volume. In this study, the USGS constructed a three-dimensional numerical finite-difference groundwater-flow model of the Willamette Basin representing the six hydrogeologic units, defined in previous investigations, as six model layers. From youngest to oldest, and [generally] uppermost to lowermost they are the: upper sedimentary unit, Willamette silt unit, middle sedimentary unit, lower sedimentary unit, Columbia River basalt unit, and basement confining unit. The high Cascade unit is not included in the groundwater-flow model because it is not present within the model boundaries. Geographic boundaries are simulated as no-flow (no water flowing in or out of the model), except where the Columbia River is simulated as a constant hydraulic head boundary. Streams are designated as head-dependent-flux boundaries, in which the flux depends on the elevation of the stream surface. Groundwater recharge from precipitation was estimated using the Precipitation-Runoff Modeling System (PRMS), a watershed model that accounts for evapotranspiration from the unsaturated zone. Evapotranspiration from the saturated zone was not considered an important component of groundwater discharge. Well pumping was simulated as specified flux and included public supply, irrigation, and industrial pumping. Hydraulic conductivity values were estimated from previous studies through aquifer slug and permeameter tests, specific capacity data, core analysis, and modeling. Upper, middle and lower sedimentary unit horizontal hydraulic conductivity values were differentiated between the Portland subbasin and the Tualatin, Central Willamette, and Southern Willamette subbasins based on preliminary model results.

A contribution to regional stratigraphic correlations of the Afro-Brazilian depression - The Dom João Stage (Brotas Group and equivalent units - Late Jurassic) in Northeastern Brazilian sedimentary basins

NASA Astrophysics Data System (ADS)

Kuchle, Juliano; Scherer, Claiton Marlon dos Santos; Born, Christian Correa; Alvarenga, Renata dos Santos; Adegas, Felipe

2011-04-01

The Dom João Stage comprises an interval with variable thickness between 100 and 1200 m, composed of fluvial, eolian and lacustrine deposits of Late Jurassic age, based mainly on the lacustrine ostracod fauna (although the top deposits may extend into the Early Cretaceous). These deposits comprise the so-called Afro-Brazilian Depression, initially characterized as containing the Brotas Group of the Recôncavo Basin (which includes the Aliança and the Sergi Formations) and subsequently extended into the Tucano, Jatobá, Camamu, Almada, Sergipe, Alagoas and Araripe Basins in northeastern Brazil, encompassing the study area of this paper. The large occurrence area of the Dom João Stage gives rise to discussions about the depositional connectivity between the basins, and the real extension of sedimentation. In the first studies of this stratigraphic interval, the Dom João Stage was strictly associated with the rift phase, as an initial stage (decades of 1960-70), but subsequent analyses considered the Dom João as an intracratonic basin or pre-rift phase - without any relation to the active mechanics of a tectonic syn-rift phase (decades of 1980-2000). The present work developed an evolutionary stratigraphic and tectonic model, based on the characterization of depositional sequences, internal flooding surfaces, depositional systems arrangement and paleoflow directions. Several outcrops on the onshore basins were used to build composite sections of each basin, comprising facies, architectural elements, depositional systems, stratigraphic and lithostratigraphic frameworks, and paleocurrents. In addition to that, over a hundred onshore and offshore exploration wells were used (only 21 of which are showed) to map the depositional sequences and generate correlation sections. These show the characteristics and relations of the Dom João Stage in each studied basin, and they were also extended to the Gabon Basin. The results indicate that there were two main phases during the Dom João Stage, in which distinctive sedimentary environments were developed, reflecting depositional system arrangements, paleoflow directions were diverse, and continuous or compartmented basins were developed.

3D modeling of seismic waves propagation in the Israeli continental shelf: soft sediments, buried canyons and their effects.

NASA Astrophysics Data System (ADS)

Tsesarsky, M.; Volk, O.; Shani-Kadmiel, S.; Gvirtzman, Z.

2016-12-01

Sedimentary wedges underlay many coastal areas, specifically along passive continental margins. Although a large portion of the world`s population is concentrated along coastal areas, relatively few studies investigated the seismic hazard related to internal structure of these wedges. This is particularly important, when the passive margin is located in proximity to active plate boundaries. Sedimentry wedges have low angles compared to fault bounded basins, hence commonly treated using 1D methods. In various locations the sedimentary wedges are transected by deep buried canyons typically filled with sediments softer than their surrounding bedrock. Such structures are found is the Mediterranean coast of Israel. Here, a sedimentary wedge and buried canyons underlay some of the country's most densely populated regions. Seismic sources can be found both at sea and on land at epicentral distances ranging from 50 to 200 km. Although this region has a proven seismic record, it has, like many other parts of the world, limited instrumental coverage and long return periods. This makes assessment of ground motions in a future earthquake difficult and highlights the importance of non-instrumental methods. We employ numerical modeling (SW4 FD code) to study seismic ground motions and their amplification atop the sedimentary wedge and canyons. This goal is a part of a larger objective aiming at developing a systematic approach for distinction between individual contributions of basin structures to the highly complex overall basin response. We show that the sedimentary wedge and buried canyon both exhibit a unique response and modeling them as one-dimensional structures could significantly underestimate seismic hazard. The sedimentary wedge exhibit amplification ratios, relative to a horizontally layered model, up to a factor of 2. This is mainly due to the amplification of Rayleigh waves traveling into the wedge from its thin side. The buried canyon structure shows a simple, "easy to use" response with considerably high PGV values and amplification ratios of up to 3 along its axis. This response is due to a geometrical focusing effect caused by the convex shape of the canyon's floor. The canyon's response is significant even where the canyon is buried deep under the surface.

Relating sedimentary processes in the Bagnold Dunes to the development of crater basin aeolian stratification

NASA Astrophysics Data System (ADS)

Ewing, R. C.; Lapotre, M. G. A.; Lewis, K. W.; Day, M. D.; Stein, N.; Rubin, D. M.; Sullivan, R. J., Jr.; Banham, S.; Thomas, N. M.; Lamb, M. P.; Gupta, S.; Fischer, W. W.

2017-12-01

Wind-blown sand dunes are ubiquitous on the surface of Mars and are a recognized component of the martian stratigraphic record. Our current knowledge of the aeolian sedimentary processes that determine dune morphology, drive dune dynamics, and create aeolian cross-stratification are based upon orbital studies of ripple and dune morphodynamics, rover observations of stratification on Mars, Earth analogs, and experimental and theoretical studies of sand movement under martian conditions. Exploration of the Bagnold Dunes by the Curiosity Rover in Gale Crater, Mars provided the first opportunity to make in situ observations of martian dunes from the grain-to-dune scale. We used the suite of cameras on Curiosity, including Navigation Camera, Mast Camera, and Mars Hand Lens Imager. We measured grainsize and identified sedimentary processes similar to processes on terrestrial dunes, such as grainfall, grainflow, and impact ripples. Impact ripple grainsize had a median of 0.103 mm. Measurements of grainflow slopes indicate a relaxation angle of 29° and grainfall slopes indicate critical angles of at least 32°. Dissimilar to terrestrial dunes, large, meter-scale ripples form on all slopes of the dunes. The ripples form both sinuous and linear crestlines, have symmetric and asymmetric profiles, range in height between 12cm and 28cm, and host grainfall, grainflow, and impact ripples. The largest ripples are interpreted to integrate the annual wind cycle within the crater, whereas smaller large ripples and impact ripples form or reorient to shorter term wind cycling. Assessment of sedimentary processes in combination with dune type across the Bagnold Dunes shows that dune-field pattern development in response to a complex crater-basin wind regime dictates the distribution of geomorphic processes. From a stratigraphic perspective, zones of highest potential accumulation correlate with zones of wind convergence, which produce complex winds and dune field patterns thereby limiting the potential distribution of types of aeolian stratification preserved within crater basins.

Near-vertical seismic reflection image using a novel acquisition technique across the Vrancea Zone and Foscani Basin, south-eastern Carpathians (Romania)

NASA Astrophysics Data System (ADS)

Panea, I.; Stephenson, R.; Knapp, C.; Mocanu, V.; Drijkoningen, G.; Matenco, L.; Knapp, J.; Prodehl, K.

2005-12-01

The DACIA PLAN (Danube and Carpathian Integrated Action on Process in the Lithosphere and Neotectonics) deep seismic sounding survey was performed in August-September 2001 in south-eastern Romania, at the same time as the regional deep refraction seismic survey VRANCEA 2001. The main goal of the experiment was to obtain new information on the deep structure of the external Carpathians nappes and the architecture of Tertiary/Quaternary basins developed within and adjacent to the seismically-active Vrancea zone, including the Focsani Basin. The seismic reflection line had a WNW-ESE orientation, running from internal East Carpathians units, across the mountainous south-eastern Carpathians, and the foreland Focsani Basin towards the Danube Delta. There were 131 shot points along the profile, with about 1 km spacing, and data were recorded with stand-alone RefTek-125s (also known as "Texans"), supplied by the University Texas at El Paso and the PASSCAL Institute. The entire line was recorded in three deployments, using about 340 receivers in the first deployment and 640 receivers in each of the other two deployments. The resulting deep seismic reflection stacks, processed to 20 s along the entire profile and to 10 s in the eastern Focsani Basin, are presented here. The regional architecture of the latter, interpreted in the context of abundant independent constraint from exploration seismic and subsurface data, is well imaged. Image quality within and beneath the thrust belt is of much poorer quality. Nevertheless, there is good evidence to suggest that a thick (˜10 km) sedimentary basin having the structure of a graben and of indeterminate age underlies the westernmost part of the Focsani Basin, in the depth range 10-25 km. Most of the crustal depth seismicity observed in the Vrancea zone (as opposed to the more intense upper mantle seismicity) appears to be associated with this sedimentary basin. The sedimentary successions within this basin and other horizons visible further to the west, beneath the Carpathian nappes, suggest that the geometry of the Neogene and recent uplift observed in the Vrancea zone, likely coupled with contemporaneous rapid subsidence in the foreland, is detached from deeper levels of the crust at about 10 km depth. The Moho lies at a depth of about 40 km along the profile, its poor expression in the reflection stack being strengthened by independent estimates from the refraction data. Given the apparent thickness of the (meta)sedimentary supracrustal units, the crystalline crust beneath this area is quite thin (< 20 km) supporting the hypothesis that there may have been delamination of (lower) continental crust in this area involved in the evolution of the seismic Vrancea zone.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGettigan, C.K.; Hunt, D.G.

Colombia, where petroleum development began in 1908, is still yielding giant and supergiant discoveries. Recent successes result from improvements in exploration technology, in infrastructure, and in terms of participation offered by the Colombian government. Colombia has 13 sedimentary basins covering an area of 700,000 sq km out of a total country area of 1,350,000 sq km, including the continental shelf. This article highlights four of the seven basins currently productive in Colombia, providing an overview of geology and recent exploration activity.

Basin-scale hydrogeologic modeling

NASA Astrophysics Data System (ADS)

Person, Mark; Raffensperger, Jeff P.; Ge, Shemin; Garven, Grant

1996-02-01

Mathematical modeling of coupled groundwater flow, heat transfer, and chemical mass transport at the sedimentary basin scale has been increasingly used by Earth scientists studying a wide range of geologic processes including the formation of excess pore pressures, infiltration-driven metamorphism, heat flow anomalies, nuclear waste isolation, hydrothermal ore genesis, sediment diagenesis, basin tectonics, and petroleum generation and migration. These models have provided important insights into the rates and pathways of groundwater migration through basins, the relative importance of different driving mechanisms for fluid flow, and the nature of coupling between the hydraulic, thermal, chemical, and stress regimes. The mathematical descriptions of basin transport processes, the analytical and numerical solution methods employed, and the application of modeling to sedimentary basins around the world are the subject of this review paper. The special considerations made to represent coupled transport processes at the basin scale are emphasized. Future modeling efforts will probably utilize three-dimensional descriptions of transport processes, incorporate greater information regarding natural geological heterogeneity, further explore coupled processes, and involve greater field applications.

Eocene Unification of Peruvian and Bolivian Altiplano Basin Depocenters

NASA Astrophysics Data System (ADS)

Saylor, J.; Sundell, K. E.; Perez, N.; Karsky, N.; Lapen, T. J.; Cárdenas, J.

2017-12-01

Paleogene evolution of the Altiplano basin has been characterized as a flexural foreland basin which developed in response to magmatic and thrust loading along its western margin. Research focused in southern Peru and Bolivia points to broadly synchronous foredeep deposition in a basin assumed to be have been contiguous from at least 14°-23°S. We investigated Paleogene strata exposed on the southwestern margin of Lake Titicaca near the Peru/Bolivia border in order to establish sediment dispersal systems, sediment sources, and the chronology of deposition. A data set of >1,000 paleocurrent measurements throughout the section consistently indicates a western sediment source. The results of detrital zircon mixture modeling are consistent with derivation from Cretaceous volcanic sources, and Cretaceous and Ordovician sedimentary strata exposed in the Western Cordillera. These results confirm previous models in which sedimentary sources for the Altiplano basin are dominated by the Western Cordillera throughout the Paleogene. The detrital zircon signatures from strata in this stratigraphic section where paleocurrent orientation is well constrained provide a benchmark for future research seeking to determine sediment sources for the Altiplano basin. However, refined chronologies based on detrital zircon U-Pb maximum depositional ages (MDAs) point to development of at least two Paleocene depocenters in Peru and Bolivia separated by a zone of nondeposition or erosion in southern Peru. The basal Muñani Formation in southern Peru yields MDAs of 36.9-40.2 Ma, which requires revision of the previously determined middle Paleocene onset of deposition. The Muñani Formation overlies the Vilquechico Group which has been biostratigraphically determined to range from Campanian-Maastrichtian (or possibly Paleocene, 60 Ma). The revised chronology for the Muñani Formation requires a disconformity of at least 20 Myr during which deposition continued in both the Peruvian and Bolivian depocenters of the Paleogene Altiplano foreland basin. This requires that the Altiplano basin initiated as separate basins, and only unified at 36-40 Ma.

Transition from alkaline to calc-alkaline volcanism during evolution of the Paleoproterozoic Francevillian basin of eastern Gabon (Western Central Africa)

NASA Astrophysics Data System (ADS)

Thiéblemont, Denis; Bouton, Pascal; Préat, Alain; Goujou, Jean-Christian; Tegyey, Monique; Weber, Francis; Ebang Obiang, Michel; Joron, Jean Louis; Treuil, Michel

2014-11-01

We report new geochemical data for the volcanic and subvolcanic rocks associated with the evolution of the Francevillian basin of eastern Gabon during Paleoproterozoic times (c. 2.1-2 Ga). Filling of this basin has proceeded through four main sedimentary or volcano-sedimentary episodes, namely FA, FB, FC and FD. Volcanism started during the FB episode being present only in the northern part of the basin (Okondja sub-basin). This volcanism is ultramafic to trachytic in composition and displays a rather constant alkaline geochemical signature. This signature is typical of a within-plate environment, consistent with the rift-setting generally postulated for the Francevillian basin during the FB period. Following FB, the FC unit is 10-20 m-thick silicic horizon (jasper) attesting for a massive input of silica in the basin. Following FC, the FD unit is a c. 200-400 m-thick volcano-sedimentary sequence including felsic tuffs and epiclastic rocks. The geochemical signatures of these rocks are totally distinct from those of the FB alkaline lavas. High Th/Ta and La/Ta ratios attest for a calc-alkaline signature and slight fractionation between heavy rare-earth suggests melting at a rather low pressure. Such characteristics are comparable to those of felsic lavas associated with the Taupo zone of New Zealand, a modern ensialic back-arc basin. Following FD, the FE detrital unit is defined only in the Okondja region, probably associated with a late-stage collapse of the northern part of the basin. It is suggested that the alkaline to calc-alkaline volcanic transition reflects the evolution of the Francevillian basin from a diverging to a converging setting, in response to the onset of converging movements in the Eburnean Belt of Central Africa.

Seismic valve as the main mechanism for sedimentary fluid entrapment within extensional basin: example of the Lodève Permian Basin (Hérault, South of France).

NASA Astrophysics Data System (ADS)

Laurent, D.; Lopez, M.; Chauvet, A.; Imbert, P.; Sauvage, A. C.; Martine, B.; Thomas, M.

2014-12-01

During syn-sedimentary burial in basin, interstitial fluids initially trapped within the sedimentary pile are easily moving under overpressure gradient. Indeed, they have a significant role on deformation during basin evolution, particularly on fault reactivation. The Lodève Permian Basin (Hérault, France) is an exhumed half graben with exceptional outcrop conditions providing access to barite-sulfides mineralized systems and hydrocarbon trapped into rollover faults of the basin. Architectural studies shows a cyclic infilling of fault zone and associated S0-parallel veins according to three main fluid events during dextral/normal faulting. Contrasting fluid entrapment conditions are deduced from textural analysis, fluid inclusion microthermometry and sulfide isotope geothermometer: (i) the first stage is characterized by an implosion breccia cemented by silicifications and barite during abrupt pressure drop within fault zone; (ii) the second stage consists in succession of barite ribbons precipitated under overpressure fluctuations, derived from fault-valve action, with reactivation planes formed by sulphide-rich micro-shearing structures showing normal movement; and (iii) the third stage is associated to the formation of dextral strike-slip pull-apart infilling by large barite crystals and contemporary hydrocarbons under suprahydrostatic pressure values. Microthermometry, sulfide and strontium isotopic compositions of the barite-sulfides veins indicate that all stages were formed by mixing between deep basinal fluids at 230°C, derived from cinerite dewatering, and formation water from overlying sedimentary cover channelized trough fault planes. We conclude to a polyphase history of fluid trapping during Permian synrift formation of the basin: (i) a first event, associated with the dextral strike-slip motion on faults, leads to a first sealing of the fault zone; (ii) periodic reactivations of fault planes and bedding-controlled shearing form the main mineralized ore bodies by the single action of fluid overpressure fluctuations, undergoing changes in local stress distribution and (iii) a final tectonic activation of fault linked to last basinal fluid and hydrocarbon migration during which shear stress restoration on fault plane is faster than fluid pressure build-up.

Overpressures in the Uinta Basin, Utah: Analysis using a three-dimensional basin evolution model

NASA Astrophysics Data System (ADS)

McPherson, Brian J. O. L.; Bredehoeft, John D.

2001-04-01

High pore fluid pressures, approaching lithostatic, are observed in the deepest sections of the Uinta basin, Utah. Geologic observations and previous modeling studies suggest that the most likely cause of observed overpressures is hydrocarbon generation. We studied Uinta overpressures by developing and applying a three-dimensional, numerical model of the evolution of the basin. The model was developed from a public domain computer code, with addition of a new mesh generator that builds the basin through time, coupling the structural, thermal, and hydrodynamic evolution. Also included in the model are in situ hydrocarbon generation and multiphase migration. The modeling study affirmed oil generation as an overpressure mechanism, but also elucidated the relative roles of multiphase fluid interaction, oil density and viscosity, and sedimentary compaction. An important result is that overpressures by oil generation create conditions for rock fracturing, and associated fracture permeability may regulate or control the propensity to maintain overpressures.

Structure of the Espanola Basin, Rio Grande Rift, New Mexico, from SAGE seismic and gravity data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferguson, J.F.; Baldridge, W.S.; Braile, L.W.

1995-04-01

Seismic and gravity data, acquired by the SAGE program over the past twelve years, are used to define the geometry of the Espanola basin and the extent of pre-Tertiary sedimentary rocks. The Paleozoic and Mesozoic units have been thinned and removed during Laramide uplift in an area now obscured by the younger rift basin. The Espanola basin is generally a shallow, asymmetric transitional structure between deeper, better developed basins to the northeast and southwest. The gravity data indicate the presence of three narrow, but deep, structural lows arrayed along the Embudo/Pajarito fault system. These sub-basins seem to be younger thanmore » the faults on the basin margins. This apparent focussing of deformation in the later history of the basin may be a response to changes in regional stress or more local accommodation of the rift extension. Future work is planned to develop seismic data over one of these sub-basins, the Velarde graben, and to better define the gravity map in order to facilitate three-dimensional modeling.« less

Accretionary prism-forearc interactions as reflected in the sedimentary fill of southern Thrace Basin (Lemnos Island, NE Greece)

NASA Astrophysics Data System (ADS)

Maravelis, A. G.; Pantopoulos, G.; Tserolas, P.; Zelilidis, A.

2015-06-01

Architecture of the well-exposed ancient forearc basin successions of northeast Aegean Sea, Greece, provides useful insights into the interplay between arc magmatism, accretionary prism exhumation, and sedimentary deposition in forearc basins. The upper Eocene-lower Oligocene basin fill of the southern Thrace forearc basin reflects the active influence of the uplifted accretionary prism. Deep-marine sediments predominate the basin fill that eventually shoals upwards into shallow-marine sediments. This trend is related to tectonically driven uplift and compression. Field, stratigraphic, sedimentological, petrographic, geochemical, and provenance data on the lower Oligocene shallow-marine deposits revealed the accretionary prism (i.e. Pindic Cordillera or Biga Peninsula) as the major contributor of sediments into the forearc region. Field investigations in these shallow-marine deposits revealed the occurrence of conglomerates with: (1) mafic and ultramafic igneous rock clasts, (2) low-grade metamorphic rock fragments, and (3) sedimentary rocks. The absence of felsic volcanic fragments rules out influence of a felsic source rock. Geochemical analysis indicates that the studied rocks were accumulated in an active tectonic setting with a sediment source of mainly mafic composition, and palaeodispersal analysis revealed a NE-NNE palaeocurrent trend, towards the Rhodopian magmatic arc. Thus, these combined provenance results make the accretionary prism the most suitable candidate for the detritus forming these shallow-marine deposits.

Warm Eocene climate enhanced petroleum generation from Cretaceous source rocks - a potential climate feedback mechanism?

NASA Astrophysics Data System (ADS)

Kroeger, K. F.; Funnell, R. H.

2012-04-01

Surface and deep sea temperatures from late Paleocene to early Eocene until the Early Eocene climatic Optimum increased by 5 - 10° C. This change was associated with a negative δ13C trend which implies major changes in global carbon cycling and enrichment of surface systems in isotopically light carbon. The degree of change in sedimentary δ13C requires emission of >10,000 gigatonnes of isotopically light carbon into the ocean. We reveal a relationship between global warming and increased petroleum generation in sedimentary basins operating on 100 kyr to Myr time scales that may explain the observed isotope shift. We use TEX86-based surface temperature data1 to predict how change in surface temperature influences the temperature evolution and resultant petroleum generation in four southwest Pacific sedimentary basins. Models predict an up to 50% increase in oil and gas expulsion rates in response to the increase in temperatures from late Paleocene to early Eocene in the region. Such an increase in petroleum generation would have significantly increased leakage of light hydrocarbons and oil degeneration products into surface systems. We propose that our modelling results are representative of a large number of sedimentary basins world-wide and that early Eocene warming has led to a synchronization of periods of maximum petroleum generation and enhanced generation in otherwise unproductive basins through extension of the volume of source rock within the oil and gas window. Extrapolating our modelling results to hundreds of sedimentary basins worldwide suggests that globally increased leakage could have led to the release of an amount of CH4, CO2 and light petroleum components into surface systems compatible with the observed changes in δ13C. We further suggest that this is a significant feedback effect, enhancing early Eocene climate warming. 1Bijl, P. K., S. Schouten, A. Sluijs, G.-J. Reichart, J. C. Zachos, and H. Brinkhuis (2009), Early Palaeogene temperature evolution of the southwest Pacific Ocean, Nature, 461, 776-779.

Areal distribution of sedimentary facies determined from seismic facies analysis and models of modern depositional systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seramur, K.C.; Powell, R.D.; Carpenter, P.J.

1988-01-01

Seismic facies analysis was applied to 3.5-kHz single-channel analog reflection profiles of the sediment fill within Muir Inlet, Glacier Bay, southeast Alaska. Nine sedimentary facies have been interpreted from seven seismic facies identified on the profiles. The interpretations are based on reflection characteristics and structural features of the seismic facies. The following reflection characteristics and structural features are used: reflector spacing, amplitude and continuity of reflections, internal reflection configurations, attitude of reflection terminations at a facies boundary, body geometry of a facies, and the architectural associations of seismic facies within each basin. The depositional systems are reconstructed by determining themore » paleotopography, bedding patterns, sedimentary facies, and modes of deposition within the basin. Muir Inlet is a recently deglaciated fjord for which successive glacier terminus positions and consequent rates of glacial retreat are known. In this environment the depositional processes and sediment characteristics vary with distance from a glacier terminus, such that during a retreat a record of these variations is preserved in the aggrading sediment fill. Sedimentary facies within the basins of lower Muir Inlet are correlated with observed depositional processes near the present glacier terminus in the upper inlet.« less

3.3 Ga SHRIMP U-Pb zircon age of a felsic metavolcanic rock from the Mundo Novo greenstone belt in the São Francisco craton, Bahia (NE Brazil)

NASA Astrophysics Data System (ADS)

Peucat, J. J.; Mascarenhas, J. F.; Barbosa, J. S. F.; de Souza, S. L.; Marinho, M. M.; Fanning, C. M.; Leite, C. M. M.

2002-07-01

Felsic metavolcanics associated with supracrustal rocks provide U-Pb zircon and Sm-Nd TDM ages of approximately 3.3 Ga, which establish an Archean age of the Mundo Novo greenstone belt. A granodioritic gneiss from the Mairi complex, located on the eastern boundary of the Mundo Novo greenstone belt, exhibits a zircon evaporation minimum age of 3.04 Ga and a Nd model age of 3.2 Ga. These results constrain the occurrence of at least three major geological units in this area: the Archean Mundo Novo greenstone belt, the Archean Mairi gneisses, and the adjoining Paleoproterozoic (<2.1 Ga) Jacobina sedimentary basin. The Jacobina basin follows the same trend as the Archean structure, extending southward to the Contendas-Mirante belt, in which a similar Archean-Paleoproterozoic association appears. We postulate that during the Paleoproterozoic in the eastern margin of the Gavião block, these Archean greenstone belts constituted a zone of weakness along which a late-stage orogenic sedimentary basin developed.

Contrasting sedimentary processes along a convergent margin: the Lesser Antilles arc system

NASA Astrophysics Data System (ADS)

Picard, Michel; Schneider, Jean-Luc; Boudon, Georges

2006-12-01

Sedimentation processes occurring in an active convergent setting are well illustrated in the Lesser Antilles island arc. The margin is related to westward subduction of the North and/or the South America plates beneath the Caribbean plate. From east to west, the arc can be subdivided into several tectono-sedimentary depositional domains: the accretionary prism, the fore-arc basin, the arc platform and inter-arc basin, and the Grenada back-arc basin. The Grenada back-arc basin, the fore-arc basin (Tobago Trough) and the accretionary prism on the east side of the volcanic arc constitute traps for particles derived from the arc platform and the South American continent. The arc is volcanically active, and provides large volumes of volcaniclastic sediments which accumulate mainly in the Grenada basin by volcaniclastic gravity flows (volcanic debris avalanches, debris flows, turbiditic flows) and minor amounts by fallout. By contrast, the eastern side of the margin is fed by ash fallout and minor volcaniclastic turbidites. In this area, the dominant component of the sediments is pelagic in origin, or derived from South America (siliciclastic turbidites). Insular shelves are the locations of carbonate sedimentation, such as large platforms which develop in the Limestone Caribbees in the northern part of the margin. Reworking of carbonate material by turbidity currents also delivers lesser amounts to eastern basins of the margin. This contrasting sedimentation on both sides of the arc platform along the margin is controlled by several interacting factors including basin morphology, volcanic productivity, wind and deep-sea current patterns, and sea-level changes. Basin morphology appears to be the most dominant factor. The western slopes of the arc platform are steeper than the eastern ones, thus favouring gravity flow processes.

Synthesis and revision of groups within the Newark Supergroup, eastern North America

USGS Publications Warehouse

Weems, R.E.; Olsen, P.E.

1997-01-01

The Newark Supergroup currently includes nine stratigraphic groups, each of which applies to part or all of the rock column of only one or a few basins. Because the group nomenclature within the Newark Supergroup is neither inclusive nor parallel in its concepts, nearly half of the strata within the Newark Supergroup lacks any group placement. A new system is proposed herein that (1) establishes unambiguous group boundaries, (2) places all Newark Supergroup strata into groups, (3) reduces the number of group names from nine to three, (4) creates parallelism between groups and three major successive tectonic events that created the rift basins containing the Newark Supergroup, and (5) coincidentally provides isochronous or nearly isochronous group boundaries. These proposed groups are (1) the Chatham Group (Middle Triassic to basal Lower Jurassic sedimentary rocks), (2) the Meriden Group (Lower Jurassic extrusive volcanic and sedimentary rocks), and (3) the Agawam Group (new name) (Lower Jurassic sedimentary rocks above all early Mesozoic igneous intrusive and extrusive rocks). This new rock classification system makes use of the fact that a discrete interval of synchronous or nearly synchronous volcanism and plutonism occurred throughout the early Mesozoic rift system of eastern North America. The presence or absence of volcanic rocks provides a powerful stratigraphic tool for establishing regional groups and group boundaries. The presence of sedimentary rocks injected by diabase dikes and sills, in the absence of extrusive volcanic rocks, places Newark Supergroup rocks in the Chatham Group. The presence of extrusive volcanic rocks, interbedded with sedimentary rocks injected by diabase dikes and sills, places Newark Supergroup rocks in the Meriden Group. The presence of sedimentary rocks lacking both extrusive volcanic rocks and diabase dikes and sills, places Newark Supergroup rocks in the Agawam Group. Application of this new regional group stratigraphy to the early Mesozoic rift basins requires revision of the stratigraphy of several basins to make formation boundaries match group boundaries.

Tectonic Evolution of the Çayirhan Neogene Basin (Ankara), Central Turkey

NASA Astrophysics Data System (ADS)

Behzad, Bezhan; Koral, Hayrettin; İşb&idot; l, Duygu; Karaaǧa; ç, Serdal

2016-04-01

Çayırhan (Ankara) is located at crossroads of the Western Anatolian extensional region, analogous to the Basin and Range Province, and suture zone of the Neotethys-Ocean, which is locus of the North Anatolian Transform since the Late Miocene. To the north of Çayırhan (Ankara), a Neogene sedimentary basin comprises Lower-Middle Miocene and Upper Miocene age formations, characterized by swamp, fluvial and lacustrine settings respectively. This sequence is folded and transected by neotectonic faults. The Sekli thrust fault is older than the Lower-Middle Miocene age formations. The Davutoǧlan fault is younger than the Lower-Middle Miocene formations and is contemporaneous to the Upper Miocene formation. The Çatalkaya fault is younger than the Upper Miocene formation. The sedimentary and tectonic features provide information on mode, timing and evolution of this Neogene age sedimentary basin in Central Turkey. It is concluded that the region underwent a period of uplift and erosion under the influence of contractional tectonics prior to the Early-Middle Miocene, before becoming a semi-closed basin under influence of transtensional tectonics during the Early-Middle Miocene and under influence of predominantly extensional tectonics during the post-Late Miocene times. Keywords: Tectonics, Extension, Transtension, Stratigraphy, Neotectonic features.

Arctic Ocean Sedimentary Cover Structure, Based on 2D MCS Seismic Data.

NASA Astrophysics Data System (ADS)

Kireev, A.; Kaminsky, V.; Poselov, V.; Poselova, L.; Kaminsky, D.

2016-12-01

In 2016 the Russian Federation has submitted its partial revised Submission for establishment of the OLCS (outer limit of the continental shelf) in the Arctic Ocean. In order to prepare the Submission, in 2005 - 2014 the Russian organizations carried out a wide range of geological and geophysical studies, so that today over 23000 km of MCS lines and 4000 km of deep seismic sounding are accomplished. For correct time/depth conversion of seismic sections obtained with a short streamer in difficult ice conditions wide-angle reflection/refraction seismic sonobuoy soundings were used. All of these seismic data were used to refine the stratigraphy model, to identify sedimentary complexes and to estimate the total thickness of the sedimentary cover. Seismic stratigraphy model was successively determined for the Cenozoic and pre-Cenozoic parts of the sedimentary section and was based on correlation of the Russian MCS data and seismic data documented by boreholes. Cenozoic part of the sedimentary cover is based on correlation of the Russian MCS data and AWI91090 section calibrated by ACEX-2004 boreholes on the Lomonosov Ridge for Amerasia basin and by correlation of onlap contacts onto oceanic crust with defined magnetic anomalies for Eurasia basin. Pre-Cenozoic part of the sedimentary cover is based on tracing major unconformities from boreholes on the Chukchi shelf (Crackerjack, Klondike, Popcorn) to the North-Chuckchi Trough and further to the Mendeleev Rise as well as to the Vilkitsky Trough and the adjacent Podvodnikov Basin. Six main unconformities were traced: regional unconformity (RU), Eocene unconformity (EoU) (for Eurasia basin only), post-Campanian unconformity (pCU), Brookian (BU - base of the Lower Brookian unit), Lower Cretaceous (LCU) and Jurassic (JU - top of the Upper Ellesmerian unit). The final step in our research was to generalize all seismic surveys (top of acoustic basement correlation data) and bathymetry data in the sedimentary cover thickness map of the Arctic Ocean and adjacent Eurasian shelf, on which the structural prolongation of the shallow shelf into deep-water is obviously seen.

Post-magmatic tectonic deformation of the outer Izu-Bonin-Mariana forearc system: initial results of IODP Expedition 352

NASA Astrophysics Data System (ADS)

Kurz, Walter; Ferré, Eric C.; Robertson, Alastair; Avery, Aaron; Christeson, Gail L.; Morgan, Sally; Kutterorf, Steffen; Sager, William W.; Carvallo, Claire; Shervais, John; Party IODP Expedition 352, Scientific

2015-04-01

IODP Expedition 352 was designed to drill through the entire volcanic sequence of the Bonin forearc. Four sites were drilled, two on the outer fore arc and two on the upper trench slope. Site survey seismic data, combined with borehole data, indicate that tectonic deformation in the outer IBM fore arc is mainly post-magmatic. Post-magmatic extension resulted in the formation of asymmetric sedimentary basins such as, for example, the half-grabens at sites 352-U1439 and 352-U1442 located on the upper trench slope. Along their eastern margins these basins are bounded by west-dipping normal faults. Sedimentation was mainly syn-tectonic. The lowermost sequence of the sedimentary units was tilted eastward by ~20°. These tilted bedding planes were subsequently covered by sub-horizontally deposited sedimentary beds. Based on biostratigraphic constraints, the minimum age of the oldest sediments is ~ 35 Ma; the timing of the sedimentary unconformities lies between ~ 27 and 32 Ma. At sites 352-U1440 and 352-U1441, located on the outer forearc, post-magmatic deformation resulted mainly in strike-slip faults possibly bounding the sedimentary basins. The sedimentary units within these basins were not significantly affected by post-sedimentary tectonic tilting. Biostratigraphic ages indicate that the minimum age of the basement-cover contact lies between ~29.5 and 32 Ma. Overall, the post-magmatic tectonic structures observed during Expedition 352 reveal a multiphase tectonic evolution of the outer IBM fore arc. At sites 352-U1439 and 352-U1442, shear with dominant reverse to oblique reverse displacement was localized along distinct subhorizontal cataclastic shear zones as well as steeply dipping slickensides and shear fractures. These structures, forming within a contractional tectonic regime, were either re-activated as or cross-cut by normal-faults as well as strike-slip faults. Extension was also accommodated by steeply dipping to subvertical mineralized veins and extensional fractures. Faults observed at sites 352-U1440 and 352-U1441 show mainly strike-slip. The sediments overlying the igneous basement, of maximum Late Eocene to Recent age, document ash and aeolian input, together with mass wasting of the fault-bounded sediment ponds.

Extensional deformation of the Guadalquivir Basin: rate of WSW-ward tectonic displacement from Upper Tortonian sedimentary rocks

NASA Astrophysics Data System (ADS)

Roldán, Francisco J.; Azañón, Jose Miguel; Rodríguez-Fernández, Jose; María Mateos, Rosa

2016-04-01

The Guadalquivir Basin (Upper Tortonian-Quaternary sedimentary infilling) has been considered the foreland basin of the Betic Orogen built up during its collision with the Sudiberian margin. The basin is currently restricted to its westernmost sector, in the Cadiz Gulf, because the Neogene-Quaternary uplift of the Betic Cordillera has produced the emersion of their central and eastern parts. The upper Tortonian chronostratigraphic unit is the oldest one and it was indistinctly deposited on the South Iberian paleomargin and the External units from the Betic Cordillera. However, these rocks are undeformed on the Sudiberian paleomargin while they are deeply affected by brittle deformation on the External Betic Zone. Outcrops of Upper Tortonian sedimentary rocks on External Betic Zone are severely fragmented showing allocthonous characters with regard to those located on the Sudiberian paleomargin. This post- Upper Tortonian deformation is not well known in the External Zones of the Cordillera where the most prominent feature is the ubiquity of a highly deformed tecto-sedimentary unit outcropping at the basement of the Guadalquivir sedimentary infilling. This tecto-sedimentary unit belongs to the Mass Wasting Extensional Complex (Rodríguez-Fernández, 2014) formed during the collision and westward migration of the Internal Zone of the Betic Cordillera (15-8,5 Ma). In the present work, we show an ensemble of tectonic, geophysical and cartographic data in order to characterize the post-Upper Tortonian deformation. For this, seismic reflection profiles have been interpreted with the help of hidrocarbon boreholes to define the thickness of the Upper Tortonian sedimentary sequence. All these data provide an estimation of the geometrical and kinematic characteristics of the extensional faults, direction of movement and rate of displacement of these rocks during Messinian/Pliocene times. References Rodríguez-Fernández, J., Roldan, F. J., J.M. Azañón y Garcia-Cortes, A. 2013. EL colapso gravitacional del frente orogénico alpino en el Dominio Subbético durante el Mioceno medio-superior: El Complejo Extensional Subbético. Boletín Geológico y Minero, 124 (3): 477-504

Basin formation and Neogene sedimentation in a backarc setting, Halmahera, eastern Indonesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, R.; Nichols, G.J.

1991-03-01

It has been proposed that basins in backarc setting form in association with subduction by thinning of continental crust, backarc spreading in oceanic crust, compression, or trapping of pieces of oceanic plate behind an arc. The Halmahera basin in eastern Indonesia developed in a backarc setting but does not fall into these categories; it formed by subsidence of thickened crust made up of imbricated Mesozoic-Paleogene arc and ophiolite rocks. Halmahera lies at the western edge of the Philippine Sea Plate in a complex zone of convergence between the Eurasian margin, the oceanic plates of the West Pacific, and the Australian/Indianmore » Plate to the south. The basement is an imbricated complex of Mesozoic to Paleogene ophiolite, arc, and arc-related rocks. During the Miocene this basement complex formed an area of thickened crust upon which carbonate reef and reef-associated sediments were deposited. The authors interpret this shallow marine region to be similar to many of the oceanic plateaus and ridges found within the Philippine Sea Plate today. In the Late Miocene, convergence between the Philippine Sea Plate and the Eurasian margin resulted in the formation of the Halmahera Trench to the west of this region of thickened crust. Subduction of the Molucca Sea Plate caused the development of a volcanic island arc. Subsidence in the backarc area produced a broad sedimentary basin filled by clastics eroded from the arc and from uplifted basement and cover rocks. The basin was asymmetric with the thickest sedimentary fill on the western side, against the volcanic arc. The Halmahera basin was modified in the Plio-Pleistocene by east-west compression as the Molucca Sea Plate was eliminated by subduction.« less

Fluid flow and sediment transport in evolving sedimentary basins

NASA Astrophysics Data System (ADS)

Swenson, John Bradley

This thesis consists of three studies that focus on groundwater flow and sediment transport in evolving sedimentary basins. The first study considers the subsurface hydrodynamic response to basin-scale transgression and regression and its implications for stratiform ore genesis. I demonstrate that the transgressive sequence focuses marginward-directed, compaction-driven discharge within a basal aquifer during progradation and deposition of the overlying regressive sequence, isolates the basal aquifer from overlying flow systems, and serves as a chemical sink for metal-bearing brines. In the second study, I develop a new theory for the shoreline response to subsidence, sediment supply, and sea level. In this theory, sediment transport in a fluvio-deltaic basin is formally equivalent to heat transfer in a two-phase (liquid and isothermal solid) system: the fluvial system is analogous to a conduction-dominated liquid phase, the shoreline is the melting front, and the water depth at the delta toe is equivalent to the latent heat of fusion. A natural consequence of this theory is that sediment-starved basins do not possess an equilibrium state. In contrast to existing theories, I do not observe either strong phase shifting or attenuation of the shoreline response to low-frequency eustatic forcing; rather, shoreline tracks sea level over a spectrum of forcing frequencies, and its response to low-frequency forcing is amplified relative to the high-frequency response. For the third study, I use a set of dimensionless numbers from the previous study as a mathematical framework for providing a unified treatment of existing stratigraphic theories. In the limit of low-amplitude eustatic forcing, my study suggests that strong phase shifting between shoreline and sea level is a consequence of specifying the sedimentation rate at the shoreline; basins free of this constraint do not develop strong phase shifts.

Linkages Between Cretaceous Forearc and Retroarc Basin Development in Southern Tibet

NASA Astrophysics Data System (ADS)

Orme, D. A.; Laskowski, A. K.

2015-12-01

Integrated provenance and subsidence analysis of forearc and retroarc foreland basin strata were used to reconstruct the evolution of the southern margin of Eurasia during the Early to Late Cretaceous. The Cretaceous-Eocene Xigaze forearc basin, preserved along ~600 km of the southern Lhasa terrane, formed between the Gangdese magmatic arc and accretionary complex as subduction of Neo-Tethyan oceanic lithosphere accommodated the northward motion and subsequent collision of the Indian plate. Petrographic similarities between Xigaze forearc basin strata and Cretaceous-Eocene sedimentary rocks of the northern Lhasa terrane, interpreted as a retroarc foreland basin, were previously interpreted to record N-S trending river systems connecting the retro- and forearc regions during Cretaceous time. New sandstone petrographic and U-Pb detrital zircon provenance analysis of Xigaze forearc basin strata support this hypothesis. Qualitative and statistical provenance analysis using cumulative distribution functions and Kolmogorov-Smirnov (K-S) tests show that the forearc basin was derived from either the same source region as or recycled from the foreland basin. Quartz-rich sandstones with abundant carbonate sedimentary lithic grains and rounded, cobble limestone clasts suggests a more distal source than the proximal Gangdese arc. Therefore, we interpret that the northern Lhasa terrane was a significant source of Xigaze forearc detritus and track spatial and temporal variability in the connection between the retro- and forearc basin systems during the Late Cretaceous. A tectonic subsidence curve for the Xigaze forearc basin shows a steep and "kinked" shape similar to other ancient and active forearc basins. Initial subsidence was likely driven by thermal relaxation of the forearc ophiolite after emplacement while additional periods of rapid subsidence likely result from periods of high flux magmatism in the Gangdese arc and changes in plate convergence rate. Comparison of the subsidence history of the Xigaze forearc basin with the Cretaceous-Eocene retroarc foreland basin reveals coeval periods of rapid subsidence, specifically during the Aptian-Turonian, suggesting that the upper-plate was in an overall state of extension.

The tectono-sedimentary evolution of the Sivas ophiolite: Implications for pre to post-obduction processes in Anatolia

NASA Astrophysics Data System (ADS)

Legeay, Etienne; Mohn, Geoffroy; Callot, Jean-Paul; Ringenbach, Jean-Claude; Müntener, Othmar; Kavak, Kaan

2016-04-01

The Eastern Mediterranean in general and Turkey in particular preserve the remnants of several Neo-Tethysian oceanic basins consumed by north-dipping subductions during the Late Cretaceous prior to collision in the Paleogene. The Sivas basin, belonging to the Late Mesozoic to Cenozoic Central Anatolian basins, is located in a key position at the junction between 1) To the North, the Izmir-Ankara-Erzincan suture zone (IAESZ), 2) To the West, the Kırsehir block, 3) To the South, the Inner-Tauride suture zone (ITSZ). The obduction of ophiolite thrust sheets occurred during Campanian along the IAESZ, and ITSZ. We focus our study on the southern boundary of the Sivas basin, where an ophiolite sequence is capped by Late Cretaceous to Paleocene post-obduction sediments. We present new field observations, new U-Pb zircon dating on magmatic rocks and geochemistry analyses to unravel the pre-obduction nature and origin of the ophiolitic basement and to describe the post-obduction tectono-sedimentary evolution. The pre-obduction evolution show that: (i) the Southern Sivas ophiolite is characterized by highly serpentinized peridotites, with minor magmatic intrusions, (ii) the top of the ophiolite is marked by detachment faulting with ophicalcites, (iii) the U-Pb zircon ages of the magmatic intrusions are constrained at ˜90 Ma, (iv) geochemical data suggest a 'subduction signature' for the magmatic rocks. The, post-obduction evolution is characterized by the emplacement of Maastrichtian and Paleocene sediments carbonate platforms located on ophiolitic highs, associated to volcanoclastics turbidites in the trench northward in the Sivas Basin. These results show that the southern Sivas ophiolite represents magma starved system sharing similarities with present-day (ultra-)slow-spreading systems. This ophiolite belongs to the ITSZ, in contrast to ophiolites located 40km northward from the IAESZ. To resolve the complex paleogeographic framework of East-Anatolia during the Cenozoic, we integrated information from ophiolite related sedimentary data and propose a new interpretation of the Eastern Anatolian paleogeography based on forearc basin geometry, consistent with the development of adjacent supra-ophiolitic basins (Ulukisla, Darende and Hekimhan).

Active Microbial Methane Production and Organic Matter Degradation in a Devonian Black Shale

NASA Astrophysics Data System (ADS)

Martini, A. M.; Petsch, S. T.; Nuesslein, K.; McIntosh, J. C.

2003-12-01

Microorganisms employ many novel strategies to derive energy and obtain nutrients, and in doing so alter the chemistry of their environments in ways that are significant for formation and transformation of geologic materials. One such strategy is natural gas generation in sedimentary basins. Previous research has shown that stable isotopic signatures of CH4, CO2 and H2O in formation waters of gas-producing black shales indicate a microbial origin for several economically viable natural gas reserves. However, these signatures leave several intriguing issues unaddressed, including the identity of the organisms and their metabolic roles and impacts on mineral, isotopic and biomarker signatures. We hypothesize that the extreme reducing conditions required for sedimentary basin methanogenesis are simply the end product of a cascade of microbial processes, initiated by anaerobic respiration of shale organic matter through NO3, SO4 and/or Fe(III) reduction, secondary processing of anaerobe biomass by fermentative organisms yielding volatile fatty acids and H2, and ultimately CO2 reduction and/or acetate fermentation to produce CH4. This research holds importance for the several aspects of the geochemical carbon cycle. It describes anaerobic hydrocarbon degradation leading to methanogenesis in a sedimentary basin; in many instances this activity has generated economically viable reserves of natural gas. It also provides a benchmark detailing how post-depositional microbial activity in rocks may confound and overprint ancient biosignatures. Interpretation of past environmental conditions depends on molecular and isotopic signatures contained in ancient sedimentary rocks, separated from signatures of metabolically similar modern microbiota living in sedimentary basins. In addition, this research sheds light on an unrecognized and thus unconstrained source of reduced gases to Earth's atmosphere, important for understanding the rates and controls on carbon cycling through geologic time.

The Itajaí foreland basin: a tectono-sedimentary record of the Ediacaran period, Southern Brazil

NASA Astrophysics Data System (ADS)

Basei, M. A. S.; Drukas, C. O.; Nutman, A. P.; Wemmer, K.; Dunyi, L.; Santos, P. R.; Passarelli, C. R.; Campos Neto, M. C.; Siga, O.; Osako, L.

2011-04-01

The Itajaí Basin located in the southern border of the Luís Alves Microplate is considered as a peripheral foreland basin related to the Dom Feliciano Belt. It presents an excellent record of the Ediacaran period, and its upper parts display the best Brazilian example of Precambrian turbiditic deposits. The basal succession of Itajaí Group is represented by sandstones and conglomerates (Baú Formation) deposited in alluvial and deltaic-fan systems. The marine upper sequences correspond to the Ribeirão Carvalho (channelized and non-channelized proximal silty-argillaceous rhythmic turbidites), Ribeirão Neisse (arkosic sandstones and siltites), and Ribeirão do Bode (distal silty turbidites) formations. The Apiúna Formation felsic volcanic rocks crosscut the sedimentary succession. The Cambrian Subida leucosyenogranite represents the last felsic magmatic activity to affect the Itajaí Basin. The Brusque Group and the Florianópolis Batholith are proposed as source areas for the sediments of the upper sequence. For the lower continental units the source areas are the Santa Catarina, São Miguel and Camboriú complexes. The lack of any oceanic crust in the Itajaí Basin suggests that the marine units were deposited in a restricted, internal sea. The sedimentation started around 600 Ma and ended before 560 Ma as indicated by the emplacement of rhyolitic domes. The Itajaí Basin is temporally and tectonically correlated with the Camaquã Basin in Rio Grande do Sul and the Arroyo del Soldado/Piriápolis Basin in Uruguay. It also has several tectono-sedimentary characteristics in common with the African-equivalent Nama Basin.

Imaging the Subsurface of the Thuringian Basin (Germany) on Different Spatial Scales

NASA Astrophysics Data System (ADS)

Goepel, A.; Krause, M.; Methe, P.; Kukowski, N.

2014-12-01

Understanding the coupled dynamics of near surface and deep fluid flow patterns is essential to characterize the properties of sedimentary basins, to identify the processes of compaction, diagenesis, and transport of mass and energy. The multidisciplinary project INFLUINS (Integrated FLUid dynamics IN Sedimentary basins) aims for investigating the behavior of fluids in the Thuringian Basin, a small intra-continental sedimentary basin in Germany, at different spatial scales, ranging from the pore scale to the extent of the entire basin. As hydraulic properties often significantly vary with spatial scales, e.g. seismic data using different frequencies are required to gain information about the spatial variability of elastic and hydraulic subsurface properties. For the Thuringian Basin, we use seismic and borehole data acquired in the framework of INFLUINS. Basin-wide structural imaging data are available from 2D reflection seismic profiles as well as 2.5D and 3D seismic travel time tomography. Further, core material from a 1,179 m deep drill hole completed in 2013 is available for laboratory seismic experiments on mm- to cm-scale. The data are complemented with logging data along the entire drill hole. This campaign yielded e.g. sonic and density logs allowing the estimation of in-situ P-velocity and acoustic impedance with a spatial resolution on the cm-scale and provides improved information about petrologic and stratigraphic variability at different scales. Joint interpretation of basin scale structural and elastic properties data with laboratory scale data from ultrasound experiments using core samples enables a detailed and realistic imaging of the subsurface properties on different spatial scales. Combining seismic travel time tomography with stratigraphic interpretation provides useful information of variations in the elastic properties for certain geological units and therefore gives indications for changes in hydraulic properties.

Characterisation of the sedimentary processes responsible for the filling and excavation of two intra mountainous basins (Agua Amarga and Collon Cura) in the Andes of Neuquén (Argentina) during the Neogene

NASA Astrophysics Data System (ADS)

Bonnel, C.; Huyghe, D.; Nivière, B.; Messager, G.; Dhont, D.; Fasentieux, B.; Hervouët, Y.; Xavier, J.-P.

2012-04-01

Intramontane basins constitute potential good recorders of orogenic systems deformation history through the documentation of their remnant sedimentary filling and observation of syntectonic growth strata. In this work, we focus on the Neuquén basin, located on the eastern flank of the Andes between 32°S and 41°S latitude. It has been structured since the late Triassic, first as back arc basin and as compressive foreland basin since the upper Cretaceous. Most of the sedimentary filling is composed of Mesozoic sediments, which have been importantly studied because of their hydrocarbon potential. On the contrary, Cenozoic tectonic and sedimentologic evolutions remain poorly documented in regard to the Mesozoic. The structural inheritance is very important and strongly influences the deformation and shortening rates from the North to the South of the basin. Thus, the northern part exhibits a classical configuration from the western high Andes, to younger fold and thrust belts and piggy-back basins to the East. On the contrary, no fold and thrust belt exist in the southern part of the basin and the deformation is restricted to the internal domain. Nevertheless, contemporaneous intramontane basins (the Agua Amarga to the North and the Collon Cura basin to the South) existed in these two parts of the basin and seem to have followed a similar evolution despite of a different structural context. To the North, the partial closing of the Agua Amarga basin by the growth of the Chuihuidos anticlines during the Miocene is characterised by the deposition of a fining upward continental sequence of ~250 m thick, from lacustrine environment at the base to alluvial and fluviatile environments in the upper part of the section. In the Collon Cura, the sedimentary filling, due to the rising of the Piedra del Aguila basement massif, reach at maximum 500 m and consist in fluvial tuffaceous material in the lower part to paleosoils and coarse conglomeratic fluvial deposits in the upper part. To the North, excavation of the Agua Amarga basin happened after regressive erosion on the external flank of the Chuihuidos anticlines and generated the deposition of an alluvial fan of 50 km length and maximum thickness of 140 m. Concerning the South, the paleolandscape conditioned the deposition of a very long (~ 20 km) but very narrow (few tens of kilometres) alluvial fan. The excavation is the consequence of the elevation cessation of the Piedra del Aguila basement.

Strong motion from surface waves in deep sedimentary basins

USGS Publications Warehouse

Joyner, W.B.

2000-01-01

It is widely recognized that long-period surface waves generated by conversion of body waves at the boundaries of deep sedimentary basins make an important contribution to strong ground motion. The factors controlling the amplitude of such motion, however, are not widely understood. A study of pseudovelocity response spectra of strong-motion records from the Los Angeles Basin shows that late-arriving surface waves with group velocities of about 1 km/sec dominate the ground motion for periods of 3 sec and longer. The rate of amplitude decay for these waves is less than for the body waves and depends significantly on period, with smaller decay for longer periods. The amplitude can be modeled by the equation log y = f(M, RE) + c + bRB where y is the pseudovelocity response, f(M, RE) is an attenuation relation based on a general strong-motion data set, M is moment magnitude, RE is the distance from the source to the edge of the basin, RB is the distance from the edge of the basin to the recording site, and b and c are parameters fit to the data. The equation gives values larger by as much as a factor of 3 than given by the attenuation relationships based on general strong-motion data sets for the same source-site distance. It is clear that surface waves need to be taken into account in the design of long-period structures in deep sedimentary basins. The ground-motion levels specified by the earthquake provisions of current building codes, in California at least, accommodate the long-period ground motions from basin-edge-generated surface waves for periods of 5 sec and less and earthquakes with moment magnitudes of 7.5 or less located more than 20 km outside the basin. There may be problems at longer periods and for earthquakes located closer to the basin edge. The results of this study suggest that anelastic attenuation may need to be included in attempts to model long-period motion in deep sedimentary basins. To obtain better data on surface waves in the future, operators of strong-motion networks should take special care for the faithful recording of the long-period components of ground motion. It will also be necessary to insure that at least some selected recorders, once triggered, continue to operate for a time sufficient for the surface waves to traverse the basin. With velocities of about 1 km/sec, that time will be as long as 100 sec for a basin the size of the Los Angeles Basin.

Assessment of Deep Seated Geothermal Reservoirs in Selected European Sedimentary Environments

NASA Astrophysics Data System (ADS)

Ungemach, Pierre; Antics, Miklos

2014-05-01

Europe at large enjoys a variety of sedimentary environments. They most often host dependable geothermal reservoirs thus favouring the farming of hot fluids, within the low to medium enthalpy range, among which geothermal district heating (GDH) and combined heat and power (CHP) undertakings hold a dominant share. Three selected reservoir settings, addressing carbonate and clastic deposits, the Central part of the Paris Basin, the Southern Germany Molasse Basin in the Münich area and the Netherland Basin respectively will be presented and the exploratory, modeling and development strategies discussed accordingly. Whereas 2D (reprocessed) and 3D seismics have become a standard in matching the distinctive (reef facies, an echelon faulting, carbonate platform layering) features of a deep buried karst and a key to drilling success in the Molasse Basin, thus emphasizing a leading exploratory rationale, the Netherland and Paris Basin instead benefit from a mature data base inherited from extensive hydrocarbon exploration campaigns, with concerns focused on reservoir modeling and sustainable management issues. As a result the lessons learned from the foregoing have enabled to build up a nucleus of expertise in the whole chain from resource identification to reservoir assessment and market penetration. The seismic risk, indeed a sensitive though somewhat emotional issue, which is requiring special attention and due microseismic monitoring from the geothermal community will also be commented.

Staff - Robert J. Gillis | Alaska Division of Geological & Geophysical

Science.gov Websites

the hydrocarbon potential of Alaska's sedimentary basins and reconstruct their geologic histories. My : Sedimentary Geology, Special Volume 182, p. 87-100. http://dx.doi.org/10.1016/j.sedgeo.2005.07.013 Selected

Sequence stratigraphy, sedimentary systems and petroleum plays in a low-accommodation basin: Middle to upper members of the Lower Jurassic Sangonghe Formation, Central Junggar Basin, Northwestern China

NASA Astrophysics Data System (ADS)

Feng, Youliang; Jiang, Shu; Wang, Chunfang

2015-06-01

The Lower Jurassic Junggar Basin is a low-accommodation basin in northwestern China. Because of low subsidence rates and a warm, wet climate, deposits of the Central subbasin of the Junggar Basin formed from fluvial, deltaic, shallow lake facies. Sequence stratigraphy and sedimentary systems of the Lower Jurassic members of the Sangonghe Formation (J1s) were evaluated by observing cores, interpreting wireline logs and examining seismic profiles. Two third-order sequences were recognized in the strata. The distribution of the sedimentary systems in the systems tracts shows that tectonic movement, paleorelief, paleoclimate and changes in lake level controlled the architecture of individual sequences. During the development of the lowstand systems tract (LST), the intense structural movement of the basin resulted in a significant fall in the water level in the lake, accompanied by rapid accommodation decrease. Braided rivers and their deltaic systems were also developed in the Central Junggar Basin. Sediments carried by braided rivers were deposited on upward slopes of the paleorelief, and braid-delta fronts were deposited on downward slopes. During the transgressive systems tract (TST), the tectonic movement of the basin was quiescent and the climate was warm and humid. Lake levels rose and accommodation increased quickly, shoal lines moved landward, and shore- to shallow-lake deposits, sublacustrine fans and deep-lake facies were deposited in shallow- to deep-lake environments. During the highstand systems tract (HST), the accommodation no longer increased but sediment supply continued, far exceeding accommodation. HST deposits slowly formed in shallow-lake to meandering river delta-front environments. Relatively low rates of structural subsidence and low accommodation resulted in coarse-grained successions that were fining upward. Deposits were controlled by structural movement and paleorelief within the LST to TST deposits in the Central subbasin. Fine- to medium-grained coarsening-upward successions developed during the HST. The sand bodies of braid-delta fronts on the downward slopes of the paleorelief in the LST and the sublacustrine fans in the TST became reservoirs for hydrocarbon accumulation. Petroleum plays have only been found in the Sangonghe Formation (J1s) located on structural ridges that consist of sand bodies comprising these sequences. Favorable conditions for petroleum plays in HST1-LST2 occur where the sand bodies have been fractured by faults and sealed by denudation and pinch-out lines, then overlain by deep lake mudstone in TST2. The favorable condition of the sand bodies within TST2 occurs where isolated sand bodies have been fractured by faults.

National Uranium Resource Evaluation: Wells Quadrangle, Nevada, Idaho, and Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Proffitt, J.L.; Mayerson, D.L.; Parker, D.P.

1982-08-01

The Wells 2/sup 0/ Quadrangle, Nevada, Idaho, and Utah, was evaluated using National Uranium Resource Evaluation criteria to delineate areas favorable for uranium deposits. Our investigation has resulted in the delineation of areas that contain Tertiary sedimentary rocks favorable for hydroallogenic deposits in the Mountain City area (Favorable Area A) and in the Oxley Peak area north of Wells (Favorable Area B). Environments considered to be unfavorable for uranium deposits include Tertiary felsic volcanic, felsic plutonic, intermediate to mafic volcanic, Paleozoic and Mesozoic sedimentary rocks, Precambrian rocks, and most Tertiary sedimentary rocks located outside the favorable areas. Present-day basins aremore » unevaluated environments because of a paucity of adequate outcrop and subsurface data. However, the scarce data indicate that some characteristics favorable for uranium deposits are present in the Susie Creek-Tule Valley-Wild Horse basin, the Contact-Granite Range-Tijuana John stocks area, the Charleston Reservoir area, and the Wells-Marys River basin.« less

Sedimentary architecture and depositional controls of a Pliocene river-dominated delta in the semi-isolated Dacian Basin, Black Sea

NASA Astrophysics Data System (ADS)

Jorissen, Elisabeth L.; de Leeuw, Arjan; van Baak, Christiaan G. C.; Mandic, Oleg; Stoica, Marius; Abels, Hemmo A.; Krijgsman, Wout

2018-06-01

Sedimentological facies models for (semi-)isolated basins are less well developed than those for marine environments, but are critical for our understanding of both present-day and ancient deltaic sediment records in restricted depositional environments. This study considers an 835 m thick sedimentary succession of mid-Pliocene age, which accumulated in the Dacian Basin, a former embayment of the Black Sea. Detailed sedimentological and palaeontological analyses reveal a regression from distal prodelta deposits with brackish water faunas to delta-top deposits with freshwater faunas. Sediments contain frequent hyperpycnal plumes and an enrichment in terrestrial organic material, ichnofossils and in situ brackish and freshwater faunas. Deltaic progradation created thin, sharply-based sand bodies formed by multiple terminal distributary channels, covering a wide depositional area. The system experienced frequent delta-lobe switching, resulting in numerous thin parasequences. Parasequences are overlain by erosive reddish oxidized sand beds, enriched in broken, abraded brackish and freshwater shells. These beds were formed after sediment starvation, on top of abandoned delta lobes during each flooding event. A robust magnetostratigraphic time frame allowed for comparison between the observed sedimentary cyclicity and the amplitude and frequency of astronomical forcing cycles. Our results indicate that parasequence frequencies are significantly higher than the number of time equivalent astronomical cycles. This suggests that delta-lobe switching was due to autogenic processes. We consider the observed facies architecture typical for a delta prograding on a low-gradient slope into a shallow, brackish, protected, semi-isolated basin. Furthermore, in the absence of significant wave and tidal influence, sediment progradation in such a protected depositional setting shaped a delta, strongly river-dominated.

Tectonics, basin analysis and organic geochemical attributes of Permian through Mesozoic deposits and their derivative oils of the Turpan-Hami basin, northwestern China

NASA Astrophysics Data System (ADS)

Greene, Todd Jeremy

The Turpan-Hami basin is a major physiographic and geologic feature of northwest China, yet considerable uncertainty exists as to the timing of its inception, its late Paleozoic and Mesozoic tectonic history, and the relationship of its petroleum systems to those of the nearby Junggar basin. Mesozoic sedimentary fades, regional unconformities, sediment dispersal patterns, and sediment compositions within the Turpan-Hami and southern Junggar basins suggest that these basins were initially separated between Early Triassic and Early Jurassic time. Prior to separation, Upper Permian profundal lacustrine and fan-delta fades and Triassic coarse-grained braided-fluvial/alluvial fades were deposited across a contiguous Junggar-Turpan-Hami basin. Permian through Triassic fades were derived mainly from the Tian Shan to the south as indicated by northward-directed paleocurrent directions and geochemical provenance of granitoid cobbles. Lower through Middle Jurassic strata begin to reflect ponded coal-forming, lake-plain environments within the Turpan-Hami basin. A sharp change in sedimentary-lithic-rich Lower Jurassic sandstone followed by a return to lithic volcanic-rich Middle Jurassic sandstone points to the initial uplift and unroofing of the largely andesitic Bogda Shan range, which first shed its sedimentary cover as it emerged to become the partition between the Turpan-Hami and southern Junggar basins. In Turpan-Hami, source rock age is one of three major statistically significant discriminators of effective source rocks in the basin. A newly developed biomarker parameter appears to track conifer evolution and can distinguish Permian rocks and their correlative oils from Jurassic coals and mudrocks, and their derivative oils. Source fades is a second key control on petroleum occurrence and character. By erecting rock-to-oil correlation models, the biomarker parameters separate oil families into end-member groups: Group 1 oils---Lower/Middle Jurassic peatland/swamp fades, Group 2 oils---Lower/Middle Jurassic marginal lacustrine fades, and Group 3 oils---Upper Permian lacusbine fades. Burial history exercises a third major control on petroleum in the Turpan-Hami basin. While relatively uninterrupted deep burial in the Tabei Depression exhausted Upper Permian source rocks and brought Lower/Middle Jurassic rocks well into the oil generative window, Late Jurassic uplift in the Tainan Depression eroded much of the Lower/Middle Jurassic section and preserved Upper Permian sourced oils as biodegraded, relict, heavy oils.* *This dissertation includes a CD that is multimedia (contains text and other applications that are not available in a printed format). The CD requires the following applications: Adobe Acrobat, UNIX.

Derivation of S and Pb in phanerozoic intrusion-related metal deposits from neoproterozoic sedimentary pyrite, Great Basin, United States

USGS Publications Warehouse

Vikre, Peter G.; Poulson, S.R.; Koenig, Alan E.

2011-01-01

The thick (≤8 km), regionally extensive section of Neoproterozoic siliciclastic strata (terrigenous detrital succession, TDS) in the central and eastern Great Basin contains sedimentary pyrite characterized by mostly high δ34S values (−11.6 to 40.8‰, >70% exceed 10‰; 51 analyses) derived from reduction of seawater sulfate, and by markedly radiogenic Pb isotopes (207Pb/204Pb >19.2; 15 analyses) acquired from clastic detritus eroded from Precambrian cratonal rocks to the east-southeast. In the overlying Paleozoic section, Pb-Zn-Cu-Ag-Au deposits associated with Jurassic, Cretaceous, and Tertiary granitic intrusions (intrusion-related metal deposits) contain galena and other sulfide minerals with S and Pb isotope compositions similar to those of TDS sedimentary pyrite, consistent with derivation of deposit S and Pb from TDS pyrite. Minor element abundances in TDS pyrite (e.g., Pb, Zn, Cu, Ag, and Au) compared to sedimentary and hydrothermal pyrite elsewhere are not noticeably elevated, implying that enrichment in source minerals is not a precondition for intrusion-related metal deposits.Three mechanisms for transferring components of TDS sedimentary pyrite to intrusion-related metal deposits are qualitatively evaluated. One mechanism involves (1) decomposition of TDS pyrite in thermal aureoles of intruding magmas, and (2) aqueous transport and precipitation in thermal or fluid mixing gradients of isotopically heavy S, radiogenic Pb, and possibly other sedimentary pyrite and detrital mineral components, as sulfide minerals in intrusion-related metal deposits. A second mechanism invokes mixing and S isotope exchange in thermal aureoles of Pb and S exsolved from magma and derived from decomposition of sedimentary pyrite. A third mechanism entails melting of TDS strata or assimilation of TDS strata by crustal or mantle magmas. TDS-derived or assimilated magmas ascend, decompress, and exsolve a mixture of TDS volatiles, including isotopically heavy S and radiogenic Pb from sedimentary pyrite, and volatiles acquired from deeper crustal or mantle sources.In the central and eastern Great Basin, the wide distribution and high density of small to mid-sized vein, replacement, and skarn intrusion-related metal deposits in lower Paleozoic rocks that contain TDS sedimentary pyrite S and Pb reflect (1) prolific Jurassic, Cretaceous, and Tertiary magmatism, (2) a regional, substrate reservoir of S and Pb in permeable and homogeneous siliciclastic strata, and (3) relatively small scale concentration of substrate and magmatic components. Large intrusion-related metal deposits in the central and eastern Great Basin acquired S and most Pb from thicker lithospheric sections.

Early Archaean collapse basins, a habitat for early bacterial life.

NASA Astrophysics Data System (ADS)

Nijman, W.

For a better definition of the sedimentary environment in which early life may have flourished during the early Archaean, understanding of the basin geometry in terms of shape, depth, and fill is a prerequisite. The basin fill is the easiest to approach, namely from the well exposed, low-grade metamorphic 3.4 - 3.5 Ga rock successions in the greenstone belts of the east Pilbara (Coppin Gap Greenstone Belt and North Pole Dome) in West Australia and of the Barberton Greenstone Belt (Buck Ridge volcano-sedimentary complex) in South Africa. They consist of mafic to ultramafic volcanic rocks, largely pillow basalts, with distinct intercalations of intermediate to felsic intrusive and volcanic rocks and of silicious sediments. The, partly volcaniclastic, silicious sediments of the Buck Ridge and North Pole volcano-sedimentary complexes form a regressive-transgressive sequence. They were deposited close to base level, and experienced occasional emersion. Both North Pole Chert and the chert of the Kittys Gap volcano-sedimentary complex in the Coppin Gap Greenstone Belt preserve the flat-and-channel architecture of a shallow tidal environment. Thickness and facies distribution appear to be genetically linked to systems, i.e. arrays, of syn-depositionally active, extensional faults. Structures at the rear, front and bottoms of these fault arrays, and the fault vergence from the basin margin towards the centre characterize the basins as due to surficial crustal collapse. Observations in the Pilbara craton point to a non-linear plan view and persistence for the basin-defining fault patterns over up to 50 Ma, during which several of these fault arrays became superposed. The faults linked high-crustal level felsic intrusions within the overall mafic rock suite via porphyry pipes, black chert veins and inferred hydrothermal circulations with the overlying felsic lavas, and more importantly, with the cherty sediments. Where such veins surfaced, high-energy breccias, and in the case of the North Pole Chert huge barite growths, are juxtaposed with the otherwise generally low-energy sediments. Such localities are interpreted as sites of hydrothermal vents. Within this large-scale geological context, many environments on the micro-scale were habitable for life, such as hydrothermal vents and their vicinities, volcanic rock surfaces, subsurface sediments and sediment surfaces. These early collapse basins, hosting this bacterial life, are only partially comparable to Earthly analogues. A resemblance with Venus' coronae and the chaos terranes on Mars is suggested. This study forms part of an international project on Earth's Earliest Sedimentary Basins, supported by the Dutch Foundation Dr. Schürmannfonds. 2

Lithogeochemical character of near-surface bedrock in the New England coastal basins

USGS Publications Warehouse

Robinson, Gilpin R.; Ayotte, Joseph D.; Montgomery, Denise L.; DeSimone, Leslie A.

2002-01-01

This geographic information system (GIS) data layer shows the generalized lithologic and geochemical, termed lithogeochemical, character of near-surface bedrock in the New England Coastal Basin (NECB) study area of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) Program. The area encompasses 23,000 square miles in western and central Maine, eastern Massachusetts, most of Rhode Island, eastern New Hampshire and a small part of eastern Connecticut. The NECB study area includes the Kennebec, Androscoggin, Saco, Merrimack, Charles, and Blackstone River Basins, as well as all of Cape Cod. Bedrock units in the NECB study area are classified into lithogeochemical units based on the relative reactivity of their constituent minerals to dissolution and the presence of carbonate or sulfide minerals. The 38 lithogeochemical units are generalized into 7 major groups: (1) carbonate-bearing metasedimentary rocks; (2) primarily noncalcareous, clastic sedimentary rocks with restricted deposition in discrete fault-bounded sedimentary basins of Mississipian or younger age; (3) primarily noncalcareous, clastic sedimentary rocks at or above biotite-grade of regional metamorphism; (4) mafic igneous rocks and their metamorphic equivalents; (5) ultramafic rocks; (6) felsic igneous rocks and their metamorphic equivalents; and (7) unconsolidated and poorly consolidated sediments.

Determination of Cenozoic sedimentary structures using integrated geophysical surveys: A case study in the Barkol Basin, Xinjiang, China

NASA Astrophysics Data System (ADS)

Sun, Kai; Chen, Chao; Du, Jinsong; Wang, Limin; Lei, Binhua

2018-01-01

Thickness estimation of sedimentary basin is a complex geological problem, especially in an orogenic environment. Intense and multiple tectonic movements and climate changes result in inhomogeneity of sedimentary layers and basement configurations, which making sedimentary structure modelling difficult. In this study, integrated geophysical methods, including gravity, magnetotelluric (MT) sounding and electrical resistivity tomography (ERT), were used to estimate basement relief to understand the geological structure and evolution of the eastern Barkol Basin in China. This basin formed with the uplift of the eastern Tianshan during the Cenozoic. Gravity anomaly map revealed the framework of the entire area, and ERT as well as MT sections reflected the geoelectric features of the Cenozoic two-layer distribution. Therefore, gravity data, constrained by MT, ERT and boreholes, were utilized to estimate the spatial distribution of the Quaternary layer. The gravity effect of the Quaternary layer related to the Tertiary layer was later subtracted to obtain the residual anomaly for inversion. For the Tertiary layer, the study area was divided into several parts because of lateral difference of density contrasts. Gravity data were interpreted to determine the density contrast constrained by the MT results. The basement relief can be verified by geological investigation, including the uplift process and regional tectonic setting. The agreement between geophysical survey and prior information from geology emphasizes the importance of integrated geophysical survey as a complementary means of geological studies in this region.

The Lusi eruption and implications for understanding fossil piercement structures in sedimentary basins

NASA Astrophysics Data System (ADS)

Svensen, Henrik; Mazzini, Adriano; Planke, Sverre; Hadi, Soffian

2016-04-01

The Lusi eruption started in northeast Java, Indonesia, on May 29th 2006, and it has been erupting rocks, mud, water, and gas ever since. We have been doing field work and research on Lusi ever since the eruption commenced. This work was initially motivated from studying the initiation of a mud volcano. However, the longevity of the eruption has made it possible to describe and monitor the lifespan of this unique piercement structure. . One of the first-order questions regarding the eruption is how it should be classified and if there are any other modern or fossil analogues that can place Lusi in a relevant geological context. During the initial stages of eruption, Lusi was classified as a mud volcano, but following geochemical studies the eruption did not show the typical CH4-dominated gas composition of other mud volcanoes and the temperature was also too high. Moreover, mud volcano eruptions normally last a few days, but Lusi never stopped during the past decade. In particular, the crater fluid geochemistry suggests a connection to the neighboring volcanic complex. Lusi represent a sedimentary hosted hydrothermal system. This opens up new possibilities for understanding fossil hydrothermal systems in sedimentary basins, such as hydrothermal vent complexes and breccia-pipes found in sedimentary basins affected by the formation of Large igneous provinces. We will present examples from the Karoo Basin (South Africa) and the Vøring Basin (offshore Norway) and discuss how Lusi can be used to refine existing formation models. Finally, by comparing Lusi to fossil hydrothermal systems we may get insight into the processes operating at depth where the Lusi system interacts with the igneous rocks of the neighbouring volcanic arc.

Sediment basin modeling through GOCE gradients controlled by thermo-isostatic constraints

NASA Astrophysics Data System (ADS)

Pivetta, Tommaso; Braitenberg, Carla

2015-04-01

Exploration of geodynamic and tectonic structures through gravity methods has experienced an increased interest in the recent years thank's to the possibilities offered by satellite gravimetry (e.g. GOCE). The main problem with potential field methods is the non-uniqueness of the underground density distributions that satisfy the observed gravity field. In terrestrial areas with scarce geological and geophysical information, valid constraints to the density model could be obtained from the application of geodynamic models. In this contribution we present the study of the gravity signals associated to the thermo-isostatic McKenzie-model (McKenzie, 1978) that predicts the development of sedimentary basins from the stretching of lithosphere. This model seems to be particularly intriguing for gravity studies as we could obtain estimates of densities and thicknesses of crust and mantle before and after a rifting event and gain important information about the time evolution of the sedimentary basin. The McKenzie-model distinguishes the rifting process into two distinct phases: a syn-rift phase that occurs instantly and is responsible of the basin formation, the thinning of lithosphere and the upwelling of hot asthenosphere. Then a second phase (post-rift), that is time dependent, and predicts further subsidence caused by the cooling of mantle and asthenosphere and subsequently increase in rock density. From the application of the McKenzie-model we have derived density underground distributions for two scenarios: the first scenario involves the lithosphere density distribution immediately after the stretching event; the second refers to the density model when thermal equilibrium between stretched and unstretched lithospheres is achieved. Calculations of gravity anomalies and gravity gradient anomalies are performed at 5km height and at the GOCE mean orbit quota (250km). We have found different gravity signals for syn-rift (gravimetric maximum) and post-rift (gravimetric minimum) scenarios and that satellite measurements are sufficiently precise to discriminate between them. The McKenzie-model is then applied to a real basin in Africa, the Benue Trough, which is an aborted rift that seems to be particularly adapt to be studied with satellite gravity techniques. McKenzie D., 1978, Some remarks on the development of sedimentary basins, Earth and Planetary Science Letters, 40, 25-32

Walled Sedimentary Basins of China: Perpetrators or Victims of Plateau Growth?

NASA Astrophysics Data System (ADS)

Carroll, A. R.; Graham, S. A.; Smith, M. E.

2004-12-01

Western China and adjacent areas of central Asia are characterized by low relief, internally drained sedimentary basins that are divided by actively uplifting mountain ranges. The margins of these basins often show evidence for extensive contractional deformation, yet their interiors are surprisingly stable. Basins such as the Tarim and Junggar also exhibit long and apparently continuous histories of closed drainage in the same approximate location (over 250 my in the case of Junggar). In contrast to traditional foreland basins, these basins are not uniquely associated with a specific thrust belt, nor do they show evidence for underlying decollements. We therefore propose the new term "walled basin", in recognition of the essential role of peripheral orogenic walls in creating and maintaining closed drainage and impounding sediments. Walled basins in Asia currently are restricted to areas that receive less than 40 cm/yr precipitation, suggesting that aridity plays a role in preventing fluvial breach of the basin walls (cf., Sobel et al., 2003). Entrapment of sediment within the closed Qaidam basin in the northeast Tibetan plateau has been implicated as a potential mechanism of plateau growth, based on the observations that the basin retains mass within the orogen and creates level topography. However, we propose that the Qaidam instead represents a walled basin that has been elevated due to underplating of the plateau, and is fated to eventual destruction as deformation continues. Several lines of reasoning support this conclusion. First, DEM analysis shows that modern drainage divides for the Qaidam and other walled basins never rise more than 1-2 km above the basin floors, limiting the amount of possible topgraphic infill. Second, the Tarim and Junggar basins presently remain well below 2000 m and probably have never been higher, despite receiving large influxes of detritus from adjacent ranges. Third, the Qaidam basin, like the Tarim and Junggar basins, has an older history of nonmarine fill that dates back at least to the Jurassic, and therefore its existence predates the Himalayan orogeny. Fourth, mid-Tertiary and older fill of the Qaidam basin has already been deformed, indicating an ongoing history of structural shortening. Finally, closed geomorphic basins within the southern Tibetan plateau are all much smaller than the Qaidam. This suggests that brittle deformation associated with progressive south to north underplating has disrupted preexisting sedimentary basins that were originally more prominent than they are now.

Inferring lateral density variations in Great Geneva Basin, western Switzerland from wells and gravity data.

NASA Astrophysics Data System (ADS)

Carrier, Aurore; Lupi, Matteo; Clerc, Nicolas; Rusillon, Elme; Do Couto, Damien

2017-04-01

In the framework of sustainable energy development Switzerland supports the growth of renewable energies. SIG (Services Industriels de Genève) and the Canton of Geneva intend to develop the use of hydrothermal energy in western Switzerland. As a Mesozoïc-formed sedimentary basin, the Great Geneva Basin (GGB) shares geological and petrophysical similarities with the Munich area (Baviera, Germany) and Paris Basin (France). The latter already provide significant amounts of geothermal energy for district heating. The prospection phase has been launched in 2014 by SIG and aims at identifying relevant geological units and defining their geometries. Lower Cretaceous and Tertiary geological units have first been targeted as potential layers. At the depth we find these units (and according to the normal geothermal gradient), low enthalpy geothermal resources are rather expected. In this framework, our study aims at constraining and refining lateral and vertical heterogeneities of Quaternary to Cretaceous sedimentary layers in GGB. Linear velocity law is inverted at wells and then interpolated to the whole basin for each geological layer. Using time pickings from available data and Quaternary information from previous studies time to depth conversion is performed. Thickness map of every geological unit is then produced. Tertiary thickness ranges from 0 m at the NW border of the GGB at the foothill of the Jura Mountains to 3000 m in the SE of the GGB at the border with the French Alps. These observations are consistent with field and well observations. The produced thickness map will be used as a geometry support for gravity data inversion and then density lateral variations estimation. Unconstrained, and a priori constrained inversion has been performed in GGB using Gauss-Newton algorithms. Velocity versus density relationships will then enable to refine velocity law interpolation. Our procedure allowed us to reduce the uncertainty of key target formation and represents an important step towards the development of geothermal energy in the Great Geneva Basin.

Modeling of wind gap formation and development of sedimentary basins during fold growth: application to the Zagros Fold Belt, Iran.

NASA Astrophysics Data System (ADS)

Collignon, Marine; Yamato, Philippe; Castelltort, Sébastien; Kaus, Boris

2016-04-01

Mountain building and landscape evolution are controlled by the interactions between river dynamics and tectonic forces. Such interactions have been largely studied but a quantitative evaluation of tectonic/geomorphic feedbacks remains required for understanding sediments routing within orogens and fold-and-thrust belts. Here, we employ numerical simulations to assess the conditions of uplift and river incision necessary to deflect an antecedent drainage network during the growth of one or several folds. We propose that a partitioning of the river network into internal (endorheic) and longitudinal drainage arises as a result of lithological differences within the deforming crustal sedimentary cover. We show with examples from the Zagros Fold Belt (ZFB) that drainage patterns can be linked to the incision ratio R between successive lithological layers, corresponding to the ratio between their relative erodibilities or incision coefficients. Transverse drainage networks develop for uplift rates smaller than 0.8 mm.yr-1 and -10 < R < 10. Intermediate drainage network are obtained for uplift rates up to 2 mm.yr-1 and incision ratios of 20. Parallel drainage networks and formation of sedimentary basins occur for large values of incision ratio (R >20) and uplift rates between 1 and 2 mm.yr-1. These results have implications for predicting the distribution of sediment depocenters in fold-and-thrust belts, which can be of direct economic interest for hydrocarbon exploration.

Buried paleo-sedimentary basins in the north-eastern Black Sea-Azov Sea area and tectonic implications (DOBRE-2)

NASA Astrophysics Data System (ADS)

Starostenko, Vitaly; Stephenson, Randell; Janik, Tomasz; Tolkunov, Anatoly

2014-05-01

A number of independent but inter-related projects carried out under the auspices of various national and international programmes in Ukraine including DARIUS were aimed at imaging the upper lithosphere, crustal and sedimentary basin architecture in the north-eastern Black Sea, southern Crimea and Kerch peninsulas and the Azov Sea. This region marks the transition from relatively undisturbed Precambrian European cratonic crust and lithosphere north of the Azov Sea to areas of significant Phanerozoic tectonics and basin development, in both extensional as well as compressional environments, to the south, including the eastern Black Sea rift, which is the main sedimentary basin of the study area. The wide-angle reflection and refraction (WARR) profile DOBRE-2, a Ukrainian national project with international participation (see below), overlapping some 115 km of the southern end of the DOBREfraction'99 profile (that crosses the intracratonic Donbas Foldbelt) in the north and running to the eastern Black Sea basin in the south, utilised on- and offshore recording and energy sources. It maps crustal velocity structure across the craton margin and documents, among other things, that the Moho deepens from 40 km to ~47 km to the southwest below the Azov Sea and Crimean-Caucasus deformed zone. A regional CDP seismic profile coincident with DOBRE-2, crossing the Azov Sea, Kerch Peninsula and the north-eastern Black Sea southwest to the Ukraine-Turkey border, acquired by Ukrgeofisika (the Ukrainian national geophysical company) reveals in its inferred structural relationships the ages of Cretaceous and younger extensional and subsequent basin inversion tectonic events as well as the 2D geometry of basement displacement associated with post mid-Eocene inversion. A direct comparison of the results of the WARR velocity model and the near-vertical reflection structural image has been made by converting the former into the time domain. The results dramatically demonstrate that there are major, rift-like, sedimentary basins underlying the area of the Azov Sea and the inverted north-eastern margin of the Black Sea. It can be speculated that one of these basins may represent the previously unknown western prolongation of the Jurassic-aged Greater Caucasus back-arc basin and that the other may be the legacy of earlier - Late Palaeozoic-Triassic - extensional tectonics in this area. Individuals (in alphabetical order) from each institution involved scientifically in DOBRE-2 (listed alphabetically according to country) include: H. Thybo (Department of Geography and Geology, University of Copenhagen, Denmark); A. Dannowski and E. Flüh (IFM-GEOMAR, Kiel, Germany); W. Czuba, A. Guterch and P. Środa (Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland); M. Grad (Institute of Geophysics, University of Warsaw, Warsaw, Poland); D. Gryn, K. Kolomiyets, O. Legostaeva, D. Lysynchuk, V. Omelchenko and O. Rusakov (Institute of Geophysics, National Academy of Sciences of Ukraine, Kyiv); M. Pobedash, N. Polyvach, G. Sydorenko and Z. Voitsytskyi (Ukrgeofisika, Kyiv, Ukraine); as well as the named co-authors of this presentation.

The Sedimentary Architecture of the Hatton Basin from New 2D Seismic Reflection and Gravity Data

NASA Astrophysics Data System (ADS)

Bérdi, L.; Prada, M.; O'Reilly, B.; Haughton, P.; Shannon, P.; Martínez-Loriente, S.

2017-12-01

The Hatton Basin is located at the western European Atlantic Margin, approximately 600 km west of Scotland and Ireland. It is bounded by the Rockall Bank to the east and by the Hatton High to the west. Little is known about its structure and evolution within the context of the North Atlantic opening. Here we present a preliminary interpretation of the large-scale sedimentary structure of the Hatton basin from new 2D regional long-streamer seismic reflection data and DSDP information. Gravity data and previous knowledge on the crustal structure of the basin are used to investigate its formation processes.First interpretations of the seismic data suggest the presence of three megasequences referred to as Ha (Early Pliocene to Holocene), Hb (Late Eocene to Late Miocene) and Hc (Paleocene to middle Eocene), which are bounded by regional unconformities C10 (intra-Early Pliocene), C30 (intra-Late Eocene) and C40 (base Cenozoic) respectively. The C20 (intra-Early Miocene) surface is absent in the basin but is locally identified to the south of the study area. The mapped regional reflectors are recognized throughout the European North Atlantic.Below the Cenozoic succession, the presence of Mesozoic and/or older rocks in the basin is proposed based on the seismic character of the reflectors and the apparent rotated fault blocks. In the lowest Cenozoic megasequence (Hc), a prograding sedimentary wedge system was identified at the basin margins that implies a relative sea level fall during this period. In Late Paleocene‒Early Eocene times, the basin was affected by extensive magmatism that resulted in the emplacement of volcanic intrusives and extrusives of basaltic origin. The deposition of megasequence Hb was controlled by strong bottom current activity as a consequence of rapid subsidence and deep marine conditions. The transition from sequence Hb to Ha is marked by the C10 unconformity, which records the late Cenozoic uplift and erosion of Ireland and Britain. Megasequence Ha is locally eroded and is characterized by contourite, debris flow and mass transport deposits. This publication has emanated from research supported in part by a research grant from Science Foundation Ireland (SFI) under Grant Number 13/RC/2092 and co-funded under the European Regional Development Fund and by PIPCO RSG and its member companies.

The immature thrust belt of the northern front of the Tianshan

NASA Astrophysics Data System (ADS)

Chen, Ke; Gumiaux, Charles; Augier, Romain; Chen, Yan; Wang, Qingchen

2010-05-01

The modern Tianshan (central Asia), which extends east-west on about 2500 km long with an average of more than 2000 m in altitude, is considered as a direct consequence of the reactivation of a Paleozoic belt due to the India - Asia collision. At first order, the finite structure of this range obviously displays a significant uprising of Paleozoic "basement" rocks - as a crustal-scale ‘pop-up' - surrounded by two Cenozoic foreland basins. In order to characterize the coupling history of this Cenozoic orogeny with its northern foreland basin (Junggar basin), a detailed structural field work has been carried out on the northern piedmont of Tianshan. From Wusu to Urumqi, on about 250 km long, the thrusting of the Paleozoic basement on the Mesozoic or Cenozoic sedimentary series of the basin is remarkably exposed along several river valleys. In contrast, in other sections, the Triassic to Jurassic sedimentary series can be followed from the basin to the range where they unconformably overlie on the Carboniferous basement. These series are only gently folded along the "range front". These features imply that, at regional-scale, the Cenozoic reactivation of the Tianshan has not produced important deformation along its contact with the juxtaposed Junggar basin. The shortening ascribed to the Cenozoic intra-continental collision would either be localized in the range, mostly accommodated by reactivated Paleozoic structures or faults in the basement units, or in the distal parts of the Junggar basin, by folds and faults within the Cenozoic sedimentary series. Alternative hypothesis would be that the Tianshan uplift and the movements associated with along its northern front structures, which are traditionally assigned to its Cenozoic reactivation, might be reduced. Such characteristic significantly differs from other well-known orogenic ranges, such as the Canadian Rocky Mountains, the Appalachians, the Pyrenees which display highly folded foreland basins and thrust belts with rather well developed range front structures. This suggests that the Tianshan intra-continental range is rather "young" and still at a primary stage of its orogenic evolution. In other words, its front may be considered as an immature thrust belt. If considering the available tomographic data across the Tianshan, its actual uplift may probably be produced by an asymmetric intracontinental deformation mechanism, i.e. a deeper subduction of the Tarim plate below the Tianshan (to the south), with respect to the one of Junggar plate to the north of the range. Consequently, the Tianshan range offers an excellent natural laboratory to study the processes of the on-going orogeny-foreland basin coupling, ancient structures reactivation as well as initiation and development of range front structures.

Age and provenance of Triassic to Cenozoic sediments of West and Central Sarawak, Malaysia

NASA Astrophysics Data System (ADS)

Breitfeld, H. Tim; Galin, Thomson; Hall, Robert

2015-04-01

Sarawak is located on the northern edge of Sundaland in NW Borneo. West and Central Sarawak include parts of the Kuching and Sibu Zones. These contain remnants of several sedimentary basins with ages from Triassic to Cenozoic. New light mineral, heavy mineral and U-Pb detrital zircon ages show differences in provenance reflecting the tectonic evolution of the region. The oldest clastic sediments are Triassic (Sadong Formation and its deep marine equivalent Kuching Formation). They were sourced by a Triassic (Carnian to Norian) volcanic arc and reworked Paleoproterozoic detritus derived from Cathaysialand. The Upper Jurassic to Cretaceous Pedawan Formation is interpreted as forearc basin fill with distinctive zircon populations indicating subduction beneath present-day West Sarawak which initiated in the Late Jurassic. Subsequent subduction until the early Late Cretaceous formed the Schwaner Mountains magmatic arc. After collision of SW Borneo and other microcontinental fragments with Sundaland in the early Late Cretaceous, deep marine sedimentation (Pedawan Formation) ceased, and there was uplift forming the regional Pedawan-Kayan unconformity. Two episodes of extension followed and were responsible for basin development on land in West Sarawak from the latest Cretaceous onwards, probably in a pull-apart setting. The first episode is associated with sediments of the Kayan Group, deposited in the Latest Cretaceous (Maastrichtian) to Eocene, and the second episode with Upper Eocene sediments of the Ketungau Basin. Zircon ages indicate volcanic activity throughout the Early Cenozoic in NW Borneo, and inherited zircon ages indicate reworking of Triassic and Cretaceous rocks. A large deep marine basin, the Rajang Basin, was north of the Lupar Line Fault in Central Sarawak (Sibu Zone) from the Late Cretaceous to the Late Eocene. Zircons from sediments of the Rajang Basin indicate they have similar ages and provenance to contemporaneous terrestrial sediments of the Kayan Group and Ketungau Basin to the south, suggesting a narrow steep continental Sundaland margin at the position of the Lupar Line, and a large-scale sedimentary connection between the terrestrial and deep marine basins in the Late Cretaceous to Late Eocene. A recent reconstruction for the proto-South China Sea proposed an isolated so-called Semitau terrane colliding with SW Borneo and Sundaland in the Late Eocene. Our data show that the area of the Kuching and Sibu Zones were connected with SW Borneo and Sundaland from the Cretaceous onwards. The Cretaceous and Cenozoic sedimentary basins were sourced by alternations of Schwaner Mountains and Malay Tin Belt rocks. Our new age and provenance data cannot be explained by an isolated Semitau terrane and a Late Eocene collision.

Evolution of a Permo-Triassic sedimentary melange, Grindstone terrane, east-central Oregon

USGS Publications Warehouse

Blome, C.D.; Nestell, M.K.

1991-01-01

Perceives the Grindstone rocks to be a sedimentary melange composed of Paleozoic limestone slide and slump blocks that became detached from a carbonate shelf fringing a volcanic knoll or edifice in Late Permian to Middle Triassic time and were intermixed with Permian and Triassic slope to basinal clastic and volcaniclastic rocks in a forearc basin setting. Paleogeographic affinities of the Grindstone limestone faunas and volcaniclastic debris in the limestone and clastic rocks all indicate deposition in promixity to an island-arc system near the North American craton. -from Authors

Florida: A Jurassic transform plate boundary

USGS Publications Warehouse

Klitgord, Kim D.; Popenoe, Peter; Schouten, Hans

1984-01-01

Magnetic, gravity, seismic, and deep drill hole data integrated with plate tectonic reconstructions substantiate the existence of a transform plate boundary across southern Florida during the Jurassic. On the basis of this integrated suite of data the pre-Cretaceous Florida-Bahamas region can be divided into the pre-Jurassic North American plate, Jurassic marginal rift basins, and a broad Jurassic transform zone including stranded blocks of pre-Mesozoic continental crust. Major tectonic units include the Suwannee basin in northern Florida containing Paleozoic sedimentary rocks, a central Florida basement complex of Paleozoic age crystalline rock, the west Florida platform composed of stranded blocks of continental crust, the south Georgia rift containing Triassic sedimentary rocks which overlie block-faulted Suwannee basin sedimentary rocks, the Late Triassic-Jurassic age Apalachicola rift basin, and the Jurassic age south Florida, Bahamas, and Blake Plateau marginal rift basins. The major tectonic units are bounded by basement hinge zones and fracture zones (FZ). The basement hinge zone represents the block-faulted edge of the North American plate, separating Paleozoic and older crustal rocks from Jurassic rifted crust beneath the marginal basins. Fracture zones separate Mesozoic marginal sedimentary basins and include the Blake Spur FZ, Jacksonville FZ, Bahamas FZ, and Cuba FZ, bounding the Blake Plateau, Bahamas, south Florida, and southeastern Gulf of Mexico basins. The Bahamas FZ is the most important of all these features because its northwest extension coincides with the Gulf basin marginal fault zone, forming the southern edge of the North American plate during the Jurassic. The limited space between the North American and the South American/African plates requires that the Jurassic transform zone, connecting the Central Atlantic and the Gulf of Mexico spreading systems, was located between the Bahamas and Cuba FZ's in the region of southern Florida. Our plate reconstructions combined with chronostratigraphic and lithostratigraphic information for the Gulf of Mexico, southern Florida, and the Bahamas indicate that the gulf was sealed off from the Atlantic waters until Callovian time by an elevated Florida-Bahamas region. Restricted influx of waters started in Callovian as a plate reorganization, and increased plate separation between North America and South America/Africa produced waterways into the Gulf of Mexico from the Pacific and possibly from the Atlantic.

New approaches in the indirect quantification of thermal rock properties in sedimentary basins: the well-log perspective

NASA Astrophysics Data System (ADS)

Fuchs, Sven; Balling, Niels; Förster, Andrea

2016-04-01

Numerical temperature models generated for geodynamic studies as well as for geothermal energy solutions heavily depend on rock thermal properties. Best practice for the determination of those parameters is the measurement of rock samples in the laboratory. Given the necessity to enlarge databases of subsurface rock parameters beyond drill core measurements an approach for the indirect determination of these parameters is developed, for rocks as well a for geological formations. We present new and universally applicable prediction equations for thermal conductivity, thermal diffusivity and specific heat capacity in sedimentary rocks derived from data provided by standard geophysical well logs. The approach is based on a data set of synthetic sedimentary rocks (clastic rocks, carbonates and evaporates) composed of mineral assemblages with variable contents of 15 major rock-forming minerals and porosities varying between 0 and 30%. Petrophysical properties are assigned to both the rock-forming minerals and the pore-filling fluids. Using multivariate statistics, relationships then were explored between each thermal property and well-logged petrophysical parameters (density, sonic interval transit time, hydrogen index, volume fraction of shale and photoelectric absorption index) on a regression sub set of data (70% of data) (Fuchs et al., 2015). Prediction quality was quantified on the remaining test sub set (30% of data). The combination of three to five well-log parameters results in predictions on the order of <15% for thermal conductivity and thermal diffusivity, and of <10% for specific heat capacity. Comparison of predicted and benchmark laboratory thermal conductivity from deep boreholes of the Norwegian-Danish Basin, the North German Basin, and the Molasse Basin results in 3 to 5% larger uncertainties with regard to the test data set. With regard to temperature models, the use of calculated TC borehole profiles approximate measured temperature logs with an error of <3°C along a 4 km deep profile. A benchmark comparison for thermal diffusivity and specific heat capacity is pending. Fuchs, Sven; Balling, Niels; Förster, Andrea (2015): Calculation of thermal conductivity, thermal diffusivity and specific heat capacity of sedimentary rocks using petrophysical well logs, Geophysical Journal International 203, 1977-2000, doi: 10.1093/gji/ggv403

Mesozoic architecture of a tract of the European-Iberian continental margin: Insights from preserved submarine palaeotopography in the Longobucco Basin (Calabria, Southern Italy)

NASA Astrophysics Data System (ADS)

Santantonio, Massimo; Fabbi, Simone; Aldega, Luca

2016-01-01

The sedimentary successions exposed in northeast Calabria document the Jurassic-Early Cretaceous tectonic-sedimentary evolution of a former segment of the European-Iberian continental margin. They are juxtaposed today to units representing the deformation of the African and Adriatic plates margins as a product of Apenninic crustal shortening. A complex pattern of unconformities reveals a multi-stage tectonic evolution during the Early Jurassic, which affected the facies and geometries of siliciclastic and carbonate successions deposited in syn- and post-rift environments ranging from fluvial to deep marine. Late Sinemurian/Early Pliensbachian normal faulting resulted in exposure of the Hercynian basement at the sea-floor, which was onlapped by marine basin-fill units. Shallow-water carbonate aprons and reefs developed in response to the production of new accommodation space, fringing the newborn islands which represent structural highs made of Paleozoic crystalline and metamorphic rock. Their drowning and fragmentation in the Toarcian led to the development of thin caps of Rosso Ammonitico facies. Coeval to these deposits, a thick (> 1 km) hemipelagic/siliciclastic succession was sedimented in neighboring hanging wall basins, which would ultimately merge with the structural high successions. Footwall blocks of the Early Jurassic rift, made of Paleozoic basement and basin-margin border faults with their onlapping basin-fill formations, are found today at the hanging wall of Miocene thrusts, overlying younger (Middle/Late Jurassic to Late Paleogene) folded basinal sediments. This paper makes use of selected case examples to describe the richly diverse set of features, ranging from paleontology to sedimentology, to structural geology, which are associated with the field identification of basin-margin unconformities. Our data provide key constraints for restoring the pre-orogenic architecture of a continental margin facing a branch of the Liguria-Piedmont ocean in the Western Tethys, and for estimating displacements and slip rates along synsedimentary faults.

Archean foreland basin tectonics in the Witwatersrand, South Africa

NASA Technical Reports Server (NTRS)

Burke, K.; Kidd, W. S. F.; Kusky, T. M.

1986-01-01

The Witwatersrand Basin of South Africa is the best-known of Archean sedimentary basins and contains some of the largest gold reserves in the world. Sediments in the basin include a lower flysch-type sequence and an upper molassic facies, both of which contain abundant silicic volcanic detritus. The strata are thicker and more proximal on the northwestern side of the basin which is, at least locally, bound by thrust faults. These features indicate that the Witwatersrand strata may have been deposited in a foreland basin and a regional geologic synthesis suggests that this basin developed initially on the cratonward side of an Andean-type arc. Remarkably similar Phanerozoic basins may be found in the southern Andes above zones of shallow subduction. It is suggested that the continental collision between the Kaapvaal and Zimbabwe Cratons at about 2.7 Ga caused further subsidence and deposition in the Witwatersrand Basin. Regional uplift during this later phase of development placed the basin on the cratonward edge of a collision-related plateau, now represented by the Limpopo Province. Similarities are seen between this phase of Witwatersrand Basin evolution and that of active basins north of the Tibetan Plateau. The geologic evidence does not agree with earlier suggestions that the Witwatersrand strata were deposited in a rift or half-graben.

Tectonics vs. Climate efficiency in triggering detrital input in sedimentary basins: the Po Plain-Venetian-Adriatic Foreland Basin (Northern Italy)

NASA Astrophysics Data System (ADS)

Amadori, Chiara; Di Giulio, Andrea; Toscani, Giovanni; Lombardi, Stefano; Milanesi, Riccardo; Panara, Yuri; Fantoni, Roberto

2017-04-01

The relative efficiency of tectonics respect to climate in triggering erosion of mountain belts is a classical but still open debate in geosciences. The fact that data both from tectonically active and inactive mountain regions in different latitudes, record a worldwide increase of sediment input to sedimentary basins during the last million years concomitantly with the cooling of global climate and its evolution toward the modern high amplitude oscillating conditions pushed some authors to conclude that Pliocene-Pleistocene climate has been more efficient than tectonics in triggering mountain erosion. Po Plain-Venetian-Adriatic Foreland System, made by the relatively independent Po Plain-Northern Adriatic Basin and Venetian-Friulian Basin, provides an ideal case of study to test this hypothesis and possibly quantify the difference between the efficiency of the two. In fact it is a relatively closed basin (i.e. without significant sediment escape) with a fairly continuous sedimentation (i.e. with a quite continuous sedimentary record) completely surrounded by collisional belts (Alps, Northern Apennines and Dinarides) that experienced only very weak tectonic activity since Calabrian time, i.e. when climate cooling and cyclicity increased the most. We present a quantitative reconstruction of the sediment flow delivered from the surrounding mountain belts to the different part of the basin during Pliocene-Pleistocene time. This flow was obtained through the 3D reconstruction of the Venetian-Friulian and Po Plain Northern Adriatic Basins architecture, performed by means of the seismic-based interpretation and time-to-depth conversion of six chronologically constrained surfaces (seismic and well log data from courtesy of ENI); moreover, a 3D decompaction of the sediment volume bounded by each couple of surfaces has been included in the workflow, in order to avoid compaction-related bias. The obtained results show in both Basins a rapid four-folds increase of the sediment input occurred since mid-Pleistocene time respect to Pliocene-Gelasian times. Even if the absolute amount of sediment arriving in the two basins is quite different, reflecting the different extension of their source regions, this increase occurred concomitantly with both the strong decrease of tectonic activity in the surrounding belts and the onset of major glaciations in the Alpine range. Therefore we argue that a cool, highly oscillating climate, causing glacial-interglacial cycles is approximately 4 times more efficient than tectonics in promoting the erosion of mountain belts and the related detrital input in the surrounding sedimentary basins.

Basin in the West Candor Chasma Layered Deposits

NASA Image and Video Library

2013-08-21

This basin in Ceti Mensa, as seen by by NASA Mars Reconnaissance Orbiter, exposes concentric rings in the sedimentary layers. Dark sand ripples and textures in the bedrock suggesting wind scouring are also apparent.

Sedimentary and Paleoceanographic Responses to the South China Sea Basin Evolution

NASA Astrophysics Data System (ADS)

Jian, Z.; Liu, Z.; Jin, H.; Larsen, H. C.; Alvarez Zarikian, C. A.; Stock, J. M.; Sun, Z.; Klaus, A.

2017-12-01

As the largest marginal sea of the western Pacific, the South China Sea (SCS) has experienced a complete Wilson cycle, which had inevitably exerted a profound impact on the sedimentary environment and ocean circulation. Based on the results of four ODP/IODP expeditions to the SCS since 1999, together with other research data in this region, this study aims to explore the sedimentary and paleoceanographic responses to the tectonic events and basin evolution in the SCS. The early history of the SCS from land to deep sea was revealed by foraminiferal fauna: (1) The SCS evolved from continental shelf to an upper bathyal environment around the Oligocene/Eocene boundary, and significantly deepened at the turn of Oligocene/Miocene; (2) The early Oligocene SCS was deep but its shelf was narrow, evidenced by the Para-Tethys type deep-sea agglutinated benthic foraminifers and abundant transported shallow-water species at ODP Site 1148. Along with the SCS basin formation and the development of this semi-closed basin, the deep-sea benthic foraminiferal δ13C decreased when the Antarctic ice sheet began to reestablish at 14 Ma, the Indonesian Seaway and the southern SCS deep-water channel were closed at 10 Ma, the Luzon arc collided with Taiwan at 6.5 Ma, and the Bashi Strait was restricted at 1.2 Ma. Nd isotopes of shark teeth at ODP Site 1148 also support these inferences. An early to middle Miocene succession of red clay was found at all sites deeper than 3500 m water depth, which may be correlated to a basin-wide event related to deep circulation of oxygenated water from the western Pacific. After the earliest late Miocene carbonate crash, the red clay disappeared while the large carbonate platforms were drowned and remarkably shrank in the SCS. Late Miocene sediments display a succession of hemi-pelagic and turbidite deposits, indicating that the deep basin entered its modern state below the CCD. Frequent turbidites ended when Pliocene growth of deep-sea manganese-nodules reoccurred in the SCS. The data show that the SCS can serve as a natural laboratory to study the relationship between paleoceanographic changes and tectonic events.

New insights from DEM's into form, process and causality in Distributive Fluvial Systems

NASA Astrophysics Data System (ADS)

Scuderi, Louis; Weissmann, Gary; Hartley, Adrian; Kindilien, Peter

2014-05-01

Recent developments in platforms and sensors, as well as advances in our ability to access these rich data sources in near real time presents geoscientists with both opportunities and problems. We currently record raster and point cloud data about the physical world at unprecedented rates with extremely high spatial and spectral resolution. Yet the ability to extract scientifically useful knowledge from such immense data sets has lagged considerably. The interrelated fields of database creation, data mining and modern geostatistics all focus on such interdisciplinary data analysis problems. In recent years these fields have made great advances in analyzing the complex real-world data such as that captured in Digital Elevation Models (DEM's) and satellite imagery and by LIDAR and other geospatially referenced data sets. However, even considering the vast increase in the use of these data sets in the past decade these methods have enjoyed only a relatively modest penetration into the geosciences when compared to data analysis in other scientific disciplines. In part, a great deal of the current research weakness is due to the lack of a unifying conceptual approach and the failure to appreciate the value of highly structured and synthesized compilations of data, organized in user-friendly formats. We report on the application of these new technologies and database approaches to global scale parameterization of Distributive Fluvial Systems (DFS) within continental sedimentary basins and illustrate the value of well-constructed databases and tool-rich analysis environments for understanding form, process and causality in these systems. We analyzed the characteristics of aggradational fluvial systems in more than 700 modern continental sedimentary basins and the links between DFS within these systems and their contributing drainage basins. Our studies show that in sedimentary basins, distributive fluvial and alluvial systems dominate the depositional environment. Consequently, we have found that studies of modern tributary drainage systems in degradational settings are likely insufficient for understanding the geomorphology expressed within these basins and ultimately for understanding the basin-scale architecture of dominantly distributive fluvial deposits preserved in the rock record.

Structural investigations in the Massif-Central, France

NASA Technical Reports Server (NTRS)

Scanvic, J. Y.

1974-01-01

This survey covered the French Massif-Central (where crystalline and volcanic rocks outcrop) and its surrounding sedimentaries, Bassin de Paris, Bassin d'Aquitaine and Rhodanian valley. One objective was the mapping of fracturing and the surveying of its relationship with known ore deposits. During this survey it was found that ERTS imagery outlines lithology in some sedimentary basins. On the other hand, in a basement area, under temperature climate conditions, lithology is rarely expressed. These observations can be related to the fact that band 5 gives excellent results above sedimentary basins in France and generally band 7 is the most useful in a basement area. Several examples show clearly the value of ERTS imagery for mapping linear features and circular structures. All the main fractures are identified with the exception of new ones found both in sedimentaries and basement areas. Other interesting findings concern sun elevation which, stereoscopic effect not being possible, simulates relief in a better way under certain conditions.

Strong ground motion prediction using virtual earthquakes.

PubMed

Denolle, M A; Dunham, E M; Prieto, G A; Beroza, G C

2014-01-24

Sedimentary basins increase the damaging effects of earthquakes by trapping and amplifying seismic waves. Simulations of seismic wave propagation in sedimentary basins capture this effect; however, there exists no method to validate these results for earthquakes that have not yet occurred. We present a new approach for ground motion prediction that uses the ambient seismic field. We apply our method to a suite of magnitude 7 scenario earthquakes on the southern San Andreas fault and compare our ground motion predictions with simulations. Both methods find strong amplification and coupling of source and structure effects, but they predict substantially different shaking patterns across the Los Angeles Basin. The virtual earthquake approach provides a new approach for predicting long-period strong ground motion.

The Mesozoic palaeo-relief and immature front belt of northern Tianshan

NASA Astrophysics Data System (ADS)

Chen, K.; Gumiaux, C.; Augier, R.; Chen, Y.; Wang, Q.

2012-04-01

The modern Tianshan (central Asia) extends east-west on about 2500 km long with an average of more than 2000 m in altitude. At first order, the finite structure of this range obviously displays a crust-scale 'pop-up' of Palaeozoic rocks surrounded by two Cenozoic foreland basins. Up to now, this range is regarded as a direct consequence of the Neogene to recent reactivation of a Palaeozoic belt due to the India - Asia collision. This study focuses on the structure of the northern front area of Tianshan and is mainly based on field structural works. In particular, relationships in between sedimentary cover and basement units allow discussing the tectonic and morphological evolution of the northern Tianshan during Mesozoic and Cenozoic times. The study area is about 250 km long, from Wusu to Urumqi, along the northern piedmont of the Tianshan. Continental sedimentary series of the basin as well as structure of the cover/basement interface can well be observed along several incised valleys. Sedimentological observations argue for a limited transport distance for Lower and Uppermost Jurassic deposits that are preserved within intra-mountainous basins or within the foreland basin, along the range front. Moreover, some of the studied geological sections show that Triassic to Jurassic sedimentary series can be continuously followed from the basin to the range where they unconformably overlie the Carboniferous basement. Such onlap type structures of the Jurassic series, on top of the Palaeozoic rock units, can also be observed at more local-scale (~a few 100 m). At different scales, our observations thus clearly evidence i) the existence of a substantial relief during Mesozoic times and ii) very limited deformation, after Mesozoic, along some segments of the northern range front. Yet, thrusting of the Palaeozoic basement on the Mesozoic or Cenozoic sedimentary series of the basin is also well exposed along some other river valleys. As a consequence, the northern front of Tianshan displays as very uncylindrical with rapid lateral transitions from one type to the other. This study shows that the Cenozoic reactivation of the Tianshan range has not yielded important deformation along its contact with the juxtaposed Junggar basin, into the studied segment. Besides, the topography of the current northern Tianshan area can not be considered as the unique consequence of Cenozoic reactivation. Finally, from a compilation of structural field observations with available seismic geophysical data, regional cross sections show only moderate shortening in the deformed belt of the northern piedmont of Tianshan. Structure of the fold-and-thrust belt looks controlled by several basement thrusts faults separating rigid blocks. This study suggests that the northern front of the intra-continental Tianshan range may be considered as an immature thrust belt and is still at an early developing stage of its orogenic evolution.

Active shortening and intermontane basin formation in the central Puna Plateau: Salar de Pocitos, NW Argentina (24° 37S, 67° 03W)

NASA Astrophysics Data System (ADS)

Strecker, M. R.; Bookhagen, B.; Alonso, R.

2012-12-01

With average elevations of about 3.7 km, the semi-arid to arid Puna Plateau is a first-order morphotectonic province of the southern central Andes and is an integral part of the world's second largest orogenic plateau. With few exceptions, this region consists of internally drained, partly coalesced sedimentary basins that are mainly bordered by 5- to 6-km high reverse-fault bounded basement ranges or volcanic edifices. The basins contain continental evaporites, volcanic and clastic deposits, typically between 3 and 5 km thick, and record protracted sedimentation since the Eo-Oligocene. While these basins and ranges are related to contraction, extensional tectonics associated with mafic volcanism characterizes the eastern and southern sectors of the Puna Plateau, while the eastern flanks of the plateau and the adjacent foreland are subjected to shortening. The changeover from contraction to extension in the Puna appears to have been diachronous. Along the SE plateau margin the changeover based on previously published age dating took place between 7 and 5 Ma, while areas in the central and northern Puna document shortening until 6 and 9 Ma, respectively. In the latter two areas, however, evidence for extension comparable to the eastern and southeastern plateau is scarce. This is compatible with our new observations from the Salar de Pocitos area in the western interior of the plateau, which has been characterized by protracted shortening from the Tertiary to the present-day. The N-S oriented Salar de Pocitos basin (435 km2) is the vestige of a formerly contiguous sedimentary basin that extended to the Salar de Arizaro in the west. Unlike many other basins in this region, the Pocitos basin is bordered by the limb of an anticline developed in Tertiary sedimentary rocks on the west, while the east side comprises the reverse-faulted range front of Sierra Qda. Honda. To the north the basin is closed by transverse-oriented late Miocene volcanic edifices, and to the south it is delimited by structural blocks. Evidence for sustained contractional tectonic activity exists along the western basin margin. Fanning of dipping strata, inclined gravel-covered pediment surfaces, and wind gaps associated with gravel derived from the Cerro Macón ~15 km to the west document late Tertiary to Pleistocene growth of the basin-bounding, approximately N-S oriented and N-plunging anticline. Late Pleistocene and Holocene lake shorelines and lacustrine deposits are also tilted eastward along the same structure. In addition, Interferometric Synthetic Aperture Radar (InSAR) measurements of deformed lake terraces in the Pocitos basin clearly document that the fold is growing and that the basin continues to be asymmetrically deformed. Taken together, the results of previous observations and our study emphasize that (1) a plateau-wide kinematic changeover from shortening to extension does not exist; (2) the kinematic changeover was rather disparate in space and time; and (3) internal sectors of the plateau continue to be shortened and the plateau margin and regions in the adjacent broken foreland have not developed through progressive eastward propagation of deformation.

Denan Depression controlled by northeast-directed Olongbulak Thrust Zone in northeastern Qaidam basin: Implications for growth of northern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Yu, Xiangjiang; Guo, Zhaojie; Zhang, Qiquan; Cheng, Xiang; Du, Wei; Wang, Zhendong; Bian, Qing

2017-10-01

The Denan Depression is a unique depression in the northeastern Qaidam basin, with a maximum Cenozoic sedimentary thickness of 5 km. Detailed field work, interpretation of seismic profiles and analyzation of well data were conducted to define the Cenozoic tectonic evolution of the northeastern Qaidam basin. All geological evidences indicate that the Denan Depression is controlled by the northeast-directed Olongbulak Thrust at its southern boundary. The Denan Depression grew in concert with the development of the northeast-directed Olongbulak Thrust at least since it began to accept the Xiaganchaigou Formation, supporting the early Cenozoic growth of the northern Tibetan Plateau. Surface and subsurface data both point to enhanced tectonic activity since the Quaternary in the northeastern Qaidam basin, leading to a more individual Denan Depression relative to the main Qaidam basin. The northern boundary of the Denan Depression is a passive boundary, and no foreland developed at the northern slope of the Denan Depression.

Sedimentary architecture of a Plio-Pleistocene proto-back-arc basin: Wanganui Basin, New Zealand

NASA Astrophysics Data System (ADS)

Proust, Jean-Noël; Lamarche, Geoffroy; Nodder, Scott; Kamp, Peter J. J.

2005-11-01

The sedimentary architecture of active margin basins, including back-arc basins, is known only from a few end-members that barely illustrate the natural diversity of such basins. Documenting more of these basins types is the key to refining our understanding of the tectonic evolution of continental margins. This paper documents the sedimentary architecture of an incipient back-arc basin 200 km behind the active Hikurangi subduction margin, North Island, New Zealand. The Wanganui Basin (WB) is a rapidly subsiding, Plio-Pleistocene sedimentary basin located at the southern termination of the extensional back-arc basin of the active Central Volcanic Region (TVZ). The WB is asymmetric with a steep, thrust-faulted, outer (arc-ward) margin and a gentle inner (craton-ward) margin. It contains a 4-km-thick succession of Plio-Pleistocene sediments, mostly lying offshore, composed of shelf platform sediments. It lacks the late molasse-like deposits derived from erosion of a subaerial volcanic arc and basement observed in classical back-arc basins. Detailed seismic stratigraphic interpretations from an extensive offshore seismic reflection data grid show that the sediment fill comprises two basin-scale mega-sequences: (1) a Pliocene (3.8 to 1.35 Ma), sub-parallel, regressive "pre-growth" sequence that overtops the uplifted craton-ward margin above the reverse Taranaki Fault, and (2) a Pleistocene (1.35 Ma to present), divergent, transgressive, "syn-growth" sequence that onlaps: (i) the craton-ward high to the west, and (ii) uplifted basement blocks associated with the high-angle reverse faults of the arc-ward margin to the east. Along strike, the sediments offlap first progressively southward (mega-sequence 1) and then southeastward (mega-sequence 2), with sediment transport funnelled between the craton- and arc-ward highs, towards the Hikurangi Trough through the Cook Strait. The change in offlap direction corresponds to the onset of arc-ward thrust faulting and the rise of the Axial Ranges at ca 1.75 Ma, resulting in 5100-5700 m of differential subsidence across the fault system. Sedimentation has propagated south- to southeast-ward over the last 4 Myrs at the tip of successive back-arc graben, volcanic arcs and the associated thermally uplifted parts of the North Island, following the southward migration of the Hikurangi subduction margin. Subsidence occurred by mantle flow-driven flexure, the result of active down-drag of the lithosphere by locking of the Hikurangi subduction interface and sediment loading. The WB is considered to be a proto-back-arc basin that represents the intermediate stage of evolution of an epicratonic shelf platform, impacted by active margin processes.

Assessment of the petroleum, coal and geothermal resources of the economic community of West African States (ECOWAS) Region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattick, Robert E.; Spencer, Frank D.; Zihlman, Frederick N.

1982-01-01

Approximately 85 percent of the land area of the ECOWAS (Economic Community of West African States) region is covered by basement rocks (igneous and highly metamorphosed rocks) or relatively thin layers of Paleozoic, Upper Precambrian, and Continental Intercalaire sedimentary rocks. These areas have little or no petroleum potential. The ECOWAS region can be divided into 13 sedimentary basins on the basis of analysis of the geologic framework of Africa. These 13 basins can be further grouped into 8 categories on the basis of similarities in stratigraphy, geologic history, and probable hydrocarbon potential. The author has attempted to summarize the petroleummore » potential within the geologic framework of the region. The coal discoveries can be summarized as follows: the Carboniferous section in the Niger Basin; the Paleocene-Maestrichtian, Maestrichtian, and Eocene sections in the Niger Delta and Benin; the Maestrichtian section in the Senegal Basin; and the Pleistocene section in Sierra Leone. The only proved commercial deposits are the Paleocene-Maestrichtian and Maestrichtian subbituminous coal beds of the Niger Delta. Some of the lignite deposits of the Niger Delta and Senegal Basin, however, may be exploitable in the future. Published literature contains limited data on heat-flow values in the ECOWAS region. It is inferred, however, from the few values available and the regional geology that the development of geothermal resources, in general, would be uneconomical. Exceptions may include a geopressured zone in the Niger Delta and areas of recent tectonic activity in the Benue Trough and Cameroon. Development of the latter areas under present economic conditions is not feasible.« less

Large-Scale Multiphase Flow Modeling of Hydrocarbon Migration and Fluid Sequestration in Faulted Cenozoic Sedimentary Basins, Southern California

NASA Astrophysics Data System (ADS)

Jung, B.; Garven, G.; Boles, J. R.

2011-12-01

Major fault systems play a first-order role in controlling fluid migration in the Earth's crust, and also in the genesis/preservation of hydrocarbon reservoirs in young sedimentary basins undergoing deformation, and therefore understanding the geohydrology of faults is essential for the successful exploration of energy resources. For actively deforming systems like the Santa Barbara Basin and Los Angeles Basin, we have found it useful to develop computational geohydrologic models to study the various coupled and nonlinear processes affecting multiphase fluid migration, including relative permeability, anisotropy, heterogeneity, capillarity, pore pressure, and phase saturation that affect hydrocarbon mobility within fault systems and to search the possible hydrogeologic conditions that enable the natural sequestration of prolific hydrocarbon reservoirs in these young basins. Subsurface geology, reservoir data (fluid pressure-temperature-chemistry), structural reconstructions, and seismic profiles provide important constraints for model geometry and parameter testing, and provide critical insight on how large-scale faults and aquifer networks influence the distribution and the hydrodynamics of liquid and gas-phase hydrocarbon migration. For example, pore pressure changes at a methane seepage site on the seafloor have been carefully analyzed to estimate large-scale fault permeability, which helps to constrain basin-scale natural gas migration models for the Santa Barbara Basin. We have developed our own 2-D multiphase finite element/finite IMPES numerical model, and successfully modeled hydrocarbon gas/liquid movement for intensely faulted and heterogeneous basin profiles of the Los Angeles Basin. Our simulations suggest that hydrocarbon reservoirs that are today aligned with the Newport-Inglewood Fault Zone were formed by massive hydrocarbon flows from deeply buried source beds in the central synclinal region during post-Miocene time. Fault permeability, capillarity forces between the fault and juxtaposition of aquifers/aquitards, source oil saturation, and rate of generation control the efficiency of a petroleum trap and carbon sequestration. This research is focused on natural processes in real geologic systems, but our results will also contribute to an understanding of the subsurface behavior of injected anthropogenic greenhouse gases, especially when targeted storage sites may be influenced by regional faults, which are ubiquitous in the Earth's crust.

The hydrocarbon cycle and its role in hyperthermals, ocean anoxic events and mass extinctions

NASA Astrophysics Data System (ADS)

Dahlgren, Torbjørn

2016-04-01

Release of light isotopic carbon, ocean oxygen deficiency and extinction characterizes the Paleocene-Eocene Thermal Maximum (PETM). The PETM carbon isotope excursion (CIE) has been linked to gas hydrate decomposition and/or methane release due to igneous intrusions in sedimentary basins. In reviewing the published geological and geochemical data it became apparent that the majority of observations are in fact compatible with a different source(s) of the light isotopic carbon, namely, that of fluids trapped in sedimentary basins. Here I make a connection between the drilled paleo-accumulations of oil and gas in the Barents Sea, their burial and tectonic history, and published data of the PETM that may be reinterpreted as to reflect large scale leakage of oil and gas accumulations. I focus on oil, as leaked oil has a preservation potential in the sedimentary record. In contrast, gas from either leaked gas accumulations or exsolution from pore waters has little preservation potential other than contributing to the CIE. Sedimentary records compatible with leaked oil is present in the Arctic Ocean and Spitsbergen as fluorescent bitumen/amorphous organic matter (AOM) with carbon isotope ratios and biomarker signatures similar to those recorded in Barents Sea oil samples. Bitumen/AOM-rich immature sediments are also found in the North Sea and unresolved complex organic matter compatible with highly weathered oil has been found as far south as Walvis Ridge, offshore Namibia. Large scale fluid leakage from sedimentary basins can also explain the increase in radiogenic Osmium and Rhenium that mimic the CIE. Also biological evidence such as the extinction of North Atlantic benthic foraminifera lineages, the A. Augustum bloom and the occurrence of malformed micro/nanno-fossils may be linked to large scale leakage of oil and diagenetically altered porewaters. The leaked oil and gas was partially re-cycled into an organic rich shale (source rock) suggesting a 'hydrocarbon cycle' exists. Based on previously noted similarities between the PETM, the Toarcian OAE and the Triassic-Jurassic and Permian-Triassic events, it is inferred that also these may have been associated with catastrophic leakage of hydrocarbons trapped in sedimentary basins.

Present and past denudation rates in the central Tianshan (Central Asia): impact of the Quaternary glaciations?

NASA Astrophysics Data System (ADS)

Charreau, J.; Puchol, N.; Blard, P.; Braucher, R.; Leanni, L.; Bourles, D. L.; Graveleau, F.; Dominguez, S.

2012-12-01

Denudation controls the mass transfer from the uplifting highlands to the lowlands basin. It impacts the isostatic compensation and hence tectonics, the rheology and may drives the Earth climate through its potential impact on atmospheric CO2. Denudation is therefore a key factor governing the evolution of the Earth's surface. Quantitative records of past denudation rates over geological time scales are thus of major importance to untangle the complex interactions between tectonics, climate and surface processes. This is particularly true at the Plio-pleistocene transition where the onset of Quaternary glaciations may have enhanced worldwide denudation rates. The Tianshan stands out as a key area to better address these problems. This range owes its impressive present high topography to the recent deformation due to the India-Asia collision and is moreover sandwiched between two large intracontinental endorheic basins where the total material eroded from the uplifting range may be deciphered from the sedimentary archive. Moreover, here, potential changes in the sediment volume are insensitive to global sea-level variations. Accurate reconstruction of past denudation rate require well-dated sedimentary archives. Over past decades, several magnetostratigraphic studies were carried out in the piedmonts, where remarkable sedimentary sections are exposed in deep rivers entrenchment which expose the thick conglomeratic Xiyu formation, initially assigned to be Plio-pleistocene in age. This led several authors to conclude that, in this region, the sediment fluxes rapidly increaseed at the onset of glaciations. However, absolute magnetostratigraphic dating unambiguously show that this formation is highly diachronous and, therefore, can't owe its origin to a climate change. Given the strong lateral facies variations, reconstruction of past denudation rates from the sedimentary archive require detailed chronostratigraphy and a knowledge of the basin geometry, both almost impossible to achieve. To reconstruct the denudation rates from the sedimentary archives, we have developed an approach based on the analyses of in situ produced cosmogenic isotope (10Be) in sediment. A pioneer study was carried out in the magnetostratigraphically dated Kuitun section. This work showed a possible transient increase in denudation rate in the drainage basin from 4 to 2Ma. Because our study was limited to one single basin and suffered from large uncertainties, it is unclear yet if this change can be related to the onset of glaciations or local tectonic activity. A critical step is to understand how the material is transferred to the basin and what are the main factors controlling the spatial distribution of present-day denudation. Therefore, we have analyzed the 10Be concentrations of 35 samples from modern river sediments located in the Northern and Southern Tianshan piedmonts. Those results will be discussed in the light of a comprehensive morphologic analyses of all the drainage basins, taking into account the influence of tectonics and climate. Finally, the derivation of paleo-denudation rate from cosmogenic isotopes must rely on independent constrained of the watershed paleotopography. Therefore, we will also presents high-resolution oxygen and carbon isotopic records of paleosol carbonates, sampled from the Kuitun section. From these records we conclude that the Kuitun He drainage basin have remained at relatively unchanged elevations for the past 10 Ma.

An Overview of Geologic Carbon Sequestration Potential in California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cameron Downey; John Clinkenbeard

2005-10-01

As part of the West Coast Regional Carbon Sequestration Partnership (WESTCARB), the California Geological Survey (CGS) conducted an assessment of geologic carbon sequestration potential in California. An inventory of sedimentary basins was screened for preliminary suitability for carbon sequestration. Criteria included porous and permeable strata, seals, and depth sufficient for critical state carbon dioxide (CO{sub 2}) injection. Of 104 basins inventoried, 27 met the criteria for further assessment. Petrophysical and fluid data from oil and gas reservoirs was used to characterize both saline aquifers and hydrocarbon reservoirs. Where available, well log or geophysical information was used to prepare basin-wide mapsmore » showing depth-to-basement and gross sand distribution. California's Cenozoic marine basins were determined to possess the most potential for geologic sequestration. These basins contain thick sedimentary sections, multiple saline aquifers and oil and gas reservoirs, widespread shale seals, and significant petrophysical data from oil and gas operations. Potential sequestration areas include the San Joaquin, Sacramento, Ventura, Los Angeles, and Eel River basins, followed by the smaller Salinas, La Honda, Cuyama, Livermore, Orinda, and Sonoma marine basins. California's terrestrial basins are generally too shallow for carbon sequestration. However, the Salton Trough and several smaller basins may offer opportunities for localized carbon sequestration.« less

Depositional environment and sedimentary of the basinal sediments in the Eibiswalder Bucht (Radl Formation and Lower Eibiswald Beds), Miocene Western Styrian Basin, Austria

NASA Astrophysics Data System (ADS)

Stingl, K.

1994-12-01

The Eibiswald Bucht is a small subbasin of the Western Styrian Basin exposing sediments of Lower Miocene age. In the past the entire sequence exposed in the Eibiswalder Bucht has been interpreted as being of fluvial/lacustrine origin; here, results are presented of detailed sedimentological investigations that lead to a revision of this concept. The lowermost siliciclastic sedimentary unit of the Eibiswalder Bucht sequence is the Radl Formation. It is overlain by the Eibiswald Beds, which are subdivided into the Lower, Middle and Upper Eibiswald Beds. The Radl Formation and the Lower Eibiswald Beds are interpreted as a fan delta complex deposited along NNW-SSE striking faults. Based on the sedimentary facies this fan delta can be subdivided into a subaerial alluvial fan facies group, a proximal delta facies group and a distal delta/prodelta facies group. The Radl Formation comprises the alluvial fan and proximal delta facies groups, the Lower Eibiswald Beds the distal delta/prodelta facies group. The alluvial fan and the proximal delta consist of diverse deposits of gravelly flows. The distal delta/prodelta consists of wave-reworked, bioturbated, low density turbidites intercalated with minor gravelly mass flows. The prodelta can be regarded as as the basin facies of the small and shallow Eibiswalder Bucht, where marine conditions prevailed. The basin was probably in part connected with the Eastern Styrian Basin, the contemporary depositional environment of the Styrian Schlier (mainly turbiditic marine offshore sediments in the Eastern Styrian Basin). Analysis of the clast composition, in conjunction with the paleotransport direction of the coarse delta mass flows of the Radl Formation, shows that the source rocks were exclusively crystalline rocks ranging from greenschists to eclogites.

Oil exploration and development in Marib/Al Jawf basin, Yemen Arab Republic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maycock, I.D.

1988-02-01

In 1981, Yemen Hunt Oil Company (YHOC) negotiated a production-sharing agreement covering 12,600 km/sup 2/ in the northeast part of the Yemen Arab Republic. A reconnaissance seismic program of 1864 km acquired in 1982 revealed the presence of a major half graben, designated the Marib/Al Jawf basin by YHOC. A sedimentary section up to 18,000 ft thick has been recognized. Geologic field mapping identified Jurassic carbonates covered by Cretaceous sands overlying Permian glaciolacustrine sediments, Paleozoic sandstones, or Precambrian basement. The first well, Alif-1, drilled in 1984, aimed at a possible Jurassic carbonate objective, encountered hydrocarbon-bearing sands in the Jurassic-Cretaceous transitionmore » between 5000 and 6000 ft. Appraisal and development drilling followed. The Alif field is believed to contain in excess of 400 million bbl of recoverable oil. Subsequent wildcat drilling has located additional accumulations while further amplifying basin stratigraphy. Rapid basin development took place in the Late Jurassic culminating with the deposition of Tithonian salt. The evaporites provide an excellent seal for hydrocarbons apparently sourced from restricted basin shales and trapped in rapidly deposited clastics.« less

AMT measurements compared with gravimetry and magnetometry for structural study of a sedimentary basin: Letlhakeng-Botlhapatlou groundwater project, Botswana

NASA Astrophysics Data System (ADS)

Bourgeois, B.; Mathieu, F.; Vachette, C.; Vaubourg, P.

1994-02-01

Within the framework of hydrogeological studies for additional water supply to the main towns of Botswana, the BRGM company has carried out a multimethod geophysical survey of a large sedimentary basin in the Kalahari desert, for the purpose of assessing its water resources. On a regional scale, gravimetry, magnetometry and audio-magnetotellurics (AMT) were used to determine the structure of the basin, which is intensely faulted into horsts and grabens. Next, a number of favourable areas were selected for detailed profiling with horizontal portable loop EM (HLEM) and DC electrical arrays to locate accurately the fractured zones at the edges of grabens, the targets for exploratory drillholes. The AMT method proved to be the most effective for mapping the basement of the basin, thanks to the good resistivity contrast between the resistive basement and its conductive cover, and to the regional constancy of sedimentary organisation of the cover. The presence of the uniformly resistive Kalahari Sands at the top of the cover was also very favourable, protecting AMT data from troublesome "static" effects. These good conditions enabled a fast and innovative quantitative interpretation of AMT soundings, determined by borehole calibration and based on the reading of the apparent resistivity at a single frequency (10 Hz).

Morphology, sedimentary features and evolution of a large palaeo submarine canyon in Qiongdongnan basin, Northern South China Sea

NASA Astrophysics Data System (ADS)

Li, Xiangquan; Fairweather, Luke; Wu, Shiguo; Ren, Jianye; Zhang, Hongjie; Quan, Xiayun; Jiang, Tao; Zhang, Cheng; Su, Ming; He, Yunlong; Wang, Dawei

2013-01-01

The large Miocene-aged palaeo canyon that extents through the Qiongdongnan basin (QDNB) and Yinggehai basin (YGHB) of Northern South China Sea has been of considerable interest both economically and scientifically over the past decade. Stemmed from this, significant research has been employed into understanding the mechanism for its existence, incision, and sedimentary fill, yet debate remains. In the first case the canyon itself is actually quite anomalous. Alone from the size (over 570 km in length and more than 8 km in width (Yuan et al., 2009)), which is considerably more than most ancient deep-water channels (REFS), the canyon's sedimentary fill is also distinctly different. Some explanations have been given to explain the canyon's origin and existence, these include increased sediment supply from the Red River which is genetically linked to uplift of the Tibetan Plateau, lowstand turbidite and mass-transport activity, reactivation and dextral displacement of the Red River Fault zone inducing erosive gravity-flows, regional tilt of the QDNB and YGHB, paleo-seafloor morphology and seal-level fluctuations. With the application of new data obtained from interpretations of a large number of 2D seismic profiles, core and well log data, and tectonic and sedimentary analysis this contribution aims to: (1) Present models to explain the Canyon's sedimentary fill and basin plain deposits, which provided significant understanding of processes pre-, syn- and post-incision and; (2) review the plausibility and likelihood of each of the controlling mechanisms, hoping to shed light on this controversial aspect. We conclude that the final erosive event that shaped the canyon is dated at 5.5 Ma. The Canyon's unusual fill is a product of variation in the interaction between turbidity currents and MTD that blocked the canyon's axis, and the reduction in gravity flow energy through time; and therefore the complete succession represents one major erosive and cut event at 5.5 Ma and thereafter multi-gravity currents fills unlike in most slope channel-fills.

Sill Emplacement and Forced Folding in the Canterbury Basin, offshore SE New Zealand

NASA Astrophysics Data System (ADS)

Reeves, Jennifer; Magee, Craig; Jackson, Christopher

2017-04-01

Sill-complexes are common in sedimentary basins worldwide. The geometry of sill-complexes and their associated deformation can be used to unravel tectono-magmatic events. For example, intruding magma may uplift the overburden and the free surface to produce forced folds that are typically either dome-shaped or flat-topped. These four-way dip closures can form suitable hydrocarbon traps and dating of onlapping of sedimentary strata allows the timing of emplacement, relative to hydrocarbon generation and migration to be assessed. Furthermore, these forced folds directly overlie the forcing intrusion and their volume is commonly assumed to equal that of the emplaced magma. This relationship between folds, which may be expressed that the Earth's surface, and magma volume is fundamental for volcano predication due to the use of ground deformation as a proxy for the location and magnitude of future eruptions. However, recent studies have demonstrated that fluidization of weak host rock can accommodate magma during non-brittle emplacement, producing little or no overburden deformation. Assessing the mechanics of intrusion-induced forced folding is therefore critical to a variety of Earth Science disciplines. Here, we use 3D seismic reflection data map four sills at a high-resolution within the underexplored Canterbury Basin, offshore SE New Zealand. We demonstrate that: (i) despite similar emplacement levels, forced folds are only developed above two of the sills, with no apparent uplift above the other two sills; (ii) onlap of sedimentary onto forced folds and associated hydrothermal vents indicates two episodes of sill emplacement in the Whaingaroan (34.6-31.8 Ma) and Opoitian (5.33-3.7 Ma); and (iii) intra-fold thickness is variable, with lower intervals within the folds displaying a flat-topped geometry overlain by sedimentary strata displaying dome-shaped folding. We discuss the formation of these forced folds as assess the role of non-brittle and inelastic deformation on the geometry and growth of forced folds.

Framework for the assessment of interaction between CO2 geological storage and other sedimentary basin resources.

PubMed

Michael, K; Whittaker, S; Varma, S; Bekele, E; Langhi, L; Hodgkinson, J; Harris, B

2016-02-01

Sedimentary basins around the world considered suitable for carbon storage usually contain other natural resources such as petroleum, coal, geothermal energy and groundwater. Storing carbon dioxide in geological formations in the basins adds to the competition for access to the subsurface and the use of pore space where other resource-based industries also operate. Managing potential impacts that industrial-scale injection of carbon dioxide may have on other resource development must be focused to prevent potential conflicts and enhance synergies where possible. Such a sustainable coexistence of various resource developments can be accomplished by implementing a Framework for Basin Resource Management strategy (FBRM). The FBRM strategy utilizes the concept of an Area of Review (AOR) for guiding development and regulation of CO2 geological storage projects and for assessing their potential impact on other resources. The AOR is determined by the expected physical distribution of the CO2 plume in the subsurface and the modelled extent of reservoir pressure increase resulting from the injection of the CO2. This information is used to define the region to be characterised and monitored for a CO2 injection project. The geological characterisation and risk- and performance-based monitoring will be most comprehensive within the region of the reservoir containing the carbon dioxide plume and should consider geological features and wells continuously above the plume through to its surface projection; this region defines where increases in reservoir pressure will be greatest and where potential for unplanned migration of carbon dioxide is highest. Beyond the expanse of the carbon dioxide plume, geological characterisation and monitoring should focus only on identified features that could be a potential migration conduit for either formation water or carbon dioxide.

Geologic Criteria for the Assessment of Sedimentary Exhalative (Sedex) Zn-Pb-Ag Deposits

USGS Publications Warehouse

Emsbo, Poul

2009-01-01

Sedex deposits account for more than 50 percent of the world's zinc and lead reserves and furnish more than 25 percent of the world's production of these two metals. This report draws on previous syntheses as well as on topical studies of deposits in sedex basins to determine the characteristics and processes that produced sedex deposits. This analysis also uses studies of the tectonic, sedimentary, and fluid evolution of modern and ancient sedimentary basins and mass balance constraints to identify the hydrothermal processes that are required to produce sedex deposits. This report demonstrates how a genetic model can be translated into geologic criteria that can be used in the U.S. Geological Survey National Assessments for sedex zinc-lead-silver deposits to define permissive tracts, assess the relative prospectivity of permissive tracts, and map favorability within permissive tracts.

The Mesozoic-Cenozoic igneous intrusions and related sediment-dominated hydrothermal activities in the South Yellow Sea Basin, the Western Pacific continental margin

NASA Astrophysics Data System (ADS)

Yumao, Pang; Xunhua, Zhang; Guolin, Xiao; Luning, Shang; Xingwei, Guo; Zhenhe, Wen

2018-04-01

Various igneous complexes were identified in multi-channel seismic reflection profiles from the South Yellow Sea Basin. It is not rare that magmatic intrusions in sedimentary basins cause strong thermal perturbations and hydrothermal activities. Some intrusion-related hydrothermal vent complexes have been identified and they are considered to originate from the deep sedimentary contact aureole around igneous intrusions and terminate in upper vents structures, and are linked by a vertical conduit system. The upper vent complexes are usually eye-shaped, dome-shaped, fault-related, crater-shaped or pock-shaped in seismic profiles. A schematic model was proposed to illustrate the structures of different types of hydrothermal vent complexes. A conceptual conduit model composed of an upper pipe-like part and a lower branching part was also derived. Hydrothermal vent complexes mainly developed during the Middle-Late Cretaceous, which is coeval with, or shortly after the intrusion. The back-arc basin evolution of the area which is related to the subduction of the Paleo-Pacific plate during the Mesozoic-Cenozoic may be the principal factor for voluminous igneous complexes and vent complexes in this area. It is significant to study the characteristics of igneous complexes and related hydrothermal vent complexes, which will have implications for the future study of this area.

Results and implications of new regional seismic lines in the Malay Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leslie, W.; Ho, W.K.; Ghani, M.A.

1994-07-01

Regional seismic data, which was previously acquired between 1968 and 1971 by early operators in the Malay Basin, has limitations because the sophisticated modern-day acquisition and processing techniques were not available. These old data do not permit confident mapping below 3 s (TWT), equivalent to approximately 3000 m subsea, but aeromagnetic data indicate that the total sedimentary thickness exceeds 13,000 m. Hence, existing regional seismic data with a record length of 5 s (TWT) is neither adequate to map deeper play opportunities nor able to aid in understanding the geological history of the basin. New plays at deeper levels maymore » exist. (1) Geochemical modeling results now predict the top of the oil generation window at depths greater than previously thought. (2) Existing gas fields occur in the upper section in areas of thickest sedimentary fill but underlying targets have not been tested. (3) Past exploration has been focused on oil and not gas in deeper structures. Because of Malaysia's rapid development and its dedication to the protection of the environment, gas is becoming an increasingly important energy source. Hence, ample internal markets for additional gas discoveries are being created. A better understanding of the Malay Basin geological history will assist in locating these potential plays. To do this, Petronas acquired approximately 3000 line km of high-quality regional seismic data to further exploration efforts in this prospective region.« less

Basement geology of the National Petroleum Reserve Alaska (NPRA), Northern Alaska

USGS Publications Warehouse

Saltus, R.W.; Hudson, T.L.; Phillips, J.D.; Kulander, C.; Dumoulin, Julie A.; Potter, C.

2002-01-01

Gravity, aeromagnetic, seismic, and borehole information enable mapping of crustal basement characteristics within the National Petroleum Reserve Alaska (NPRA). In general, the pre-Mississippian basement of the southern portion of the NPRA is different from that in the north in that it is deeper and thinner, is made up of dense magnetic rocks, is cut by more normal faults, and underlies thicker accumulations of Mississippian to Triassic Ellesmerian sequence sedimentary rocks. Mafic igneous rocks within the basement and locally within the deeper Ellesmerian sequence sedimentary section could explain the observed density and magnetic variations. Because these variations spatially overlap thicker Ellesmerian sequence sediment accumulations, they may have developed, at least in part, during Mississippian to Triassic extension and basin formation. If this period of extension, and postulated mafic magmatism, was accompanied by higher heat flow, then early Ellesmerian sequence clastic sediments may have become mature for hydrocarbon generation (Magoon and Bird, 1988). This could have produced an early petroleum system in the Colville basin.

Influence of Fault-Controlled Topography on Fluvio-Deltaic Sedimentary Systems in Eberswalde Crater, Mars

NASA Technical Reports Server (NTRS)

Rice, Melissa S.; Gupta, Sanjeev; Bell, James F., III; Warner, Nicholas H.

2011-01-01

Eberswalde crater was selected as a candidate landing site for the Mars Science Laboratory (MSL) mission based on the presence of a fan-shaped sedimentary deposit interpreted as a delta. We have identified and mapped five other candidate fluvio -deltaic systems in the crater, using images and digital terrain models (DTMs) derived from the Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX). All of these systems consist of the same three stratigraphic units: (1) an upper layered unit, conformable with (2) a subpolygonally fractured unit, unconformably overlying (3) a pitted unit. We have also mapped a system of NNE-trending scarps interpreted as dip-slip faults that pre-date the fluvial -lacustrine deposits. The post-impact regional faulting may have generated the large-scale topography within the crater, which consists of a Western Basin, an Eastern Basin, and a central high. This topography subsequently provided depositional sinks for sediment entering the crater and controlled the geomorphic pattern of delta development.

RECONNAISSANCE ASSESSMENT OF CO2 SEQUESTRATION POTENTIAL IN THE TRIASSIC AGE RIFT BASIN TREND OF SOUTH CAROLINA, GEORGIA, AND NORTHERN FLORIDA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blount, G.; Millings, M.

2011-08-01

A reconnaissance assessment of the carbon dioxide (CO{sub 2}) sequestration potential within the Triassic age rift trend sediments of South Carolina, Georgia and the northern Florida Rift trend was performed for the Office of Fossil Energy, National Energy Technology Laboratory (NETL). This rift trend also extends into eastern Alabama, and has been termed the South Georgia Rift by previous authors, but is termed the South Carolina, Georgia, northern Florida, and eastern Alabama Rift (SGFAR) trend in this report to better describe the extent of the trend. The objectives of the study were to: (1) integrate all pertinent geologic information (literaturemore » reviews, drilling logs, seismic data, etc.) to create an understanding of the structural aspects of the basin trend (basin trend location and configuration, and the thickness of the sedimentary rock fill), (2) estimate the rough CO{sub 2} storage capacity (using conservative inputs), and (3) assess the general viability of the basins as sites of large-scale CO{sub 2} sequestration (determine if additional studies are appropriate). The CO{sub 2} estimates for the trend include South Carolina, Georgia, and northern Florida only. The study determined that the basins within the SGFAR trend have sufficient sedimentary fill to have a large potential storage capacity for CO{sub 2}. The deeper basins appear to have sedimentary fill of over 15,000 feet. Much of this fill is likely to be alluvial and fluvial sedimentary rock with higher porosity and permeability. This report estimates an order of magnitude potential capacity of approximately 137 billion metric tons for supercritical CO{sub 2}. The pore space within the basins represent hundreds of years of potential storage for supercritical CO{sub 2} and CO{sub 2} stored in aqueous form. There are many sources of CO{sub 2} within the region that could use the trend for geologic storage. Thirty one coal fired power plants are located within 100 miles of the deepest portions of these basins. There are also several cement and ammonia plants near the basins. Sixteen coal fired power plants are present on or adjacent to the basins which could support a low pipeline transportation cost. The current geological information is not sufficient to quantify specific storage reservoirs, seals, or traps. There is insufficient hydrogeologic information to quantify the saline nature of the water present within all of the basins. Water data in the Dunbarton Basin of the Savannah River Site indicates dissolved solids concentrations of greater than 10,000 parts per million (not potential drinking water). Additional reservoir characterization is needed to take advantage of the SGFAR trend for anthropogenic CO{sub 2} storage. The authors of this report believe it would be appropriate to study the reservoir potential in the deeper basins that are in close proximity to the current larger coal fired power plants (Albany-Arabi, Camilla-Ocilla, Alamo-Ehrhardt, and Jedburg basin).« less

The evolution of a Late Cretaceous-Cenozoic intraplate basin (Duaringa Basin), eastern Australia: evidence for the negative inversion of a pre-existing fold-thrust belt

NASA Astrophysics Data System (ADS)

Babaahmadi, Abbas; Sliwa, Renate; Esterle, Joan; Rosenbaum, Gideon

2017-12-01

The Duaringa Basin in eastern Australia is a Late Cretaceous?-early Cenozoic sedimentary basin that developed simultaneously with the opening of the Tasman and Coral Seas. The basin occurs on the top of an earlier (Permian-Triassic) fold-thrust belt, but the negative inversion of this fold-thrust belt, and its contribution to the development of the Duaringa Basin, are not well understood. Here, we present geophysical datasets, including recently surveyed 2D seismic reflection lines, aeromagnetic and Bouguer gravity data. These data provide new insights into the structural style in the Duaringa Basin, showing that the NNW-striking, NE-dipping, deep-seated Duaringa Fault is the main boundary fault that controlled sedimentation in the Duaringa Basin. The major activity of the Duaringa Fault is observed in the southern part of the basin, where it has undergone the highest amount of displacement, resulting in the deepest and oldest depocentre. The results reveal that the Duaringa Basin developed in response to the partial negative inversion of the pre-existing Permian-Triassic fold-thrust belt, which has similar orientation to the extensional faults. The Duaringa Fault is the negative inverted part of a single Triassic thrust, known as the Banana Thrust. Furthermore, small syn-depositional normal faults at the base of the basin likely developed due to the reactivation of pre-existing foliations, accommodation faults, and joints associated with Permian-Triassic folds. In contrast to equivalent offshore basins, the Duaringa Basin lacks a complex structural style and thick syn-rift sediments, possibly because of the weakening of extensional stresses away from the developing Tasman Sea.

Utilizing borehole electrical images to interpret lithofacies of fan-delta: A case study of Lower Triassic Baikouquan Formation in Mahu Depression, Junggar Basin, China

NASA Astrophysics Data System (ADS)

Yuan, Rui; Zhang, Changmin; Tang, Yong; Qu, Jianhua; Guo, Xudong; Sun, Yuqiu; Zhu, Rui; Zhou, Yuanquan (Nancy)

2017-11-01

Large-scale conglomerate fan-delta aprons were typical deposits on the slope of Mahu Depression during the Early Triassic. Without outcrops, it is difficult to study the lithofacies only by examining the limited cores from the main oil-bearing interval of the Baikouquan Formation. Borehole electrical imaging log provides abundant high-resolution geologic information that is obtainable only from real rocks previously. Referring to the lithology and sedimentary structure of cores, a case study of fan-deltas in the Lower Triassic Baikouquan Formation of the Mahu Depression presents a methodology for interpreting the complicated lithofacies utilizing borehole electrical images. Eleven types of lithologies and five types of sedimentary structures are summarized in borehole electrical images. The sediments are fining upward from gravel to silt and clay in the Baikouquan Formation. Fine-pebbles and granules are the main deposits in T1b1 and T1b2, but sandstones, siltstones and mudstones are more developed in T1b3. The main sedimentary textures are massive beddings, cross beddings and scour-and-fill structures. Parallel and horizontal beddings are more developed in T1b3 relatively. On integrated analysis of the lithology and sedimentary structure, eight lithofacies from electrical images, referred to as image lithofacies, is established for the fan-deltas. Granules to coarse-pebbles within massive beddings, granules to coarse-pebbles within cross and parallel beddings, siltstones within horizontal and massive beddings are the most developed lithofacies respectively in T1b1, T1b2 and T1b3. It indicates a gradual rise of the lake level of Mahu depression during the Early Triassic, with the fan-delta aprons retrograding towards to the margin of the basin. Therefore, the borehole electrical imaging log compensate for the limitation of cores of the Baikouquan Formation, providing an effective new approach to interpret the lithofacies of fan-delta.

Investigations of young (< 2.94 Ma) Hadar Formation deposits and their implication for basin development in southern Afar, Ethiopia

NASA Astrophysics Data System (ADS)

DiMaggio, E.; Arrowsmith, R.; Campisano, C. J.; Johnson, R. A.; Deino, A. L.; Warren, M.; Fisseha, S.; Cohen, A. S.

2014-12-01

Sedimentary deposits in Pliocene extensional rift basins in the Afar Depression, Ethiopia chronicle the evolution and paleoenvironmental context of early humans. In the lower Awash Valley, the long-studied Hadar Basin still lacks constraints on basin development during the onset and termination of Hadar Formation (~3.8 - 2.94 Ma) sedimentation. Here we present new mapping and analysis of tephra deposits from a 26 meter-thick section of sediments exposed in the central Ledi-Geraru project area at Gulfaytu, including 20 m of sediments and tephras conformably overlying a 2.94 Ma tephra marker bed (BKT-2U) that previously served as the uppermost dated tephra of the Hadar Formation. Within the overlying 20 meters of primarily lacustrine strata, we identified eight post-BKT-2U tuffs; four were suitable for geochemical characterization, and one yielded an 40Ar/39Ar age of 2.931 ± 0.034 Ma. Based on regional sedimentation rates and the tephra 40Ar/39Ar age, we infer that the newly mapped Hadar Formation at Gulfaytu represents ca. 20 kyr of post-BKT-2 sedimentation. An erosional surface marked by a conglomerate truncates the strata at Gulfaytu, and shows similarities to the well-documented Busidima unconformity surface to the southwest, suggesting that structural changes after 2.93 Ma also affected basin conditions in central Ledi-Geraru. Furthermore, subsurface geophysical investigations support a model whereby deposition rates and the stratigraphic thickness of paleo-Lake Hadar sediments are greatest in the central Ledi-Geraru, ~20 km northeast of the well-exposed lacustrine-dominated sediments of the Hadar Formation. In addition to preserving a record of post-BKT-2 strata, the central Ledi Geraru hosts the thickest subsurface lacustrine sedimentary record within the Hadar Basin hitherto described, making central Ledi-Geraru an ideal location for collecting a continuous core by the Hominin Sites and Paleolakes Drilling Project (HSPDP).

Cenozoic evolution of the Socotra Island: opening of the Gulf of Aden

NASA Astrophysics Data System (ADS)

Razin, P.; Robin, C.; Serra Kiel, J.; Leroy, S.; Bellahsen, N.; Khanbari, K.

2009-12-01

A complete stratigraphic and geological map revision of the Tertiary of Socotra Island is undertaken in order to better characterize the geometry and the tecto-sedimentary evolution of the southern margin of the Gulf of Aden, and compare them with those of the conjugate northern margin in Oman. An increase of the rate of subsidence is recorded during the Late Eocene and is associated with a transgressive peak within carbonate platform deposits (Aydim Fm.). At the scale of the Arabian plate, the extent of this platform is reduced to the future rift area. This evolution of the platform system shows a modification of the sedimentary profiles, controlled by the beginning of the rifting. The syn-rift deposits of the Early Oligocene correspond to sub-reef carbonate platform facies (Ashawq Fm.). First, the throw of synsedimentary faults and the movements linked with differential subsidence are widely compensated by carbonate production which manages to maintain a platform profile. These movements are recorded by thickness variations, significant lateral variations in the platform facies and by a local inversion of sedimentary polarities controlled by the tilting of faulted blocks. Like on the northern margin, an acceleration of the extension process leads, during the Late Oligocene, to a collapse of the platform and to the creation of deep sub-basins with carbonate gravity-flow sedimentation. Marginal reef platforms keep growing at this stage on the structural highs and feed gravity-flow sedimentary systems. The sedimentation rate stays then relatively low in the basin, forming a complex topography of the margin, marked by a segmentation into numerous sub-basins more or less connected and separated by submarine escarpments marked by wedges of breccia deposits along active normal faults. In different points, these faults are sealed by sedimentary deposits characterized by progressive unconformities and onlap geometries on the fault escarpments. These geometries show the relatively short length of the phase of « stretching » of the continental crust. Around the end of the Early Miocene, the progradation of conglomerate fan-delta deposits locally results in the fill of the basins and shows a major phase of uplift. It is very rapidly followed by a new phase of subsidence which allows the preservation of thick fan-delta and equivalent reef platform complex unconformably overlying different units of the syn-rift and pre-rift sequences, or even the exhumed Proterozoic basement. This tectonic-sedimentary phase is interpreted as synchronous to the continental breakup and the onset of the OCT at the foot of the margin. The analogy with the phase of development of «sag basins» on the Atlantic margins has to be analyzed. This major uplift at the transition syn-rift/post-rift seems to be expressed symmetrically on both margins. These syn-OCT deposits are then uplifted and affected by late tilting events. However, the most recent deposits, probably Late Miocene to plio-Quaternary in age, have only been affected by small uplifts, unlike those of the Dhofar on the northern margin

Modeling of Wave Propagation in the Osaka Sedimentary Basin during the 2013 Awaji Island Earthquake (Mw5.8)

NASA Astrophysics Data System (ADS)

Asano, K.; Sekiguchi, H.; Iwata, T.; Yoshimi, M.; Hayashida, T.; Saomoto, H.; Horikawa, H.

2013-12-01

The three-dimensional velocity structure model for the Osaka sedimentary basin, southwest Japan is developed and improved based on many kinds of geophysical explorations for decades (e.g., Kagawa et al., 1993; Horikawa et al., 2003; Iwata et al., 2008). Recently, our project (Sekiguchi et al., 2013) developed a new three-dimensional velocity model for strong motion prediction of the Uemachi fault earthquake in the Osaka basin considering both geophysical and geological information by adding newly obtained exploration data such as reflection surveys, microtremor surveys, and receiver function analysis (hereafter we call UMC2013 model) . On April 13, 2013, an inland earthquake of Mw5.8 occurred in Awaji Island, which is close to the southwestern boundary of the aftershock area of the 1995 Kobe earthquake. The strong ground motions are densely observed at more than 100 stations in the basin. The ground motion lasted longer than four minutes in the Osaka urban area where its bedrock depth is about 1-2 km. This long-duration ground motions are mainly due to the surface waves excited in this sedimentary basin whereas the magnitude of this earthquake is moderate and the rupture duration is expected to be less than 5 s. In this study, we modeled long-period (more than 2s) ground motions during this earthquake to check the performance of the present UMC2013 model and to obtain a better constraint on the attenuation factor of sedimentary part of the basin. The seismic wave propagation in the region including the source and the Osaka basin is modeled by the finite difference method using the staggered grid solving the elasto-dynamic equations. The domain of 90km×85km×25.5km is modeled and discretized with a grid spacing of 50 m. Since the minimum S-wave velocity of the UMC2013 model is about 250 m/s, this calculation is valid up to the period of about 1 s. The effect of attenuation is included in the form of Q(f)=Q0(T0/T) proposed by Graves (1996). A PML is implemented in the side and bottom of the domain. It is parallelized by the MPI and OpenMP. We computed for 120000 steps with a time step of 0.0025 s, which equals to 300s from the origin time. The source is represented by a point source having the focal mechanism determined by the F-net, NIED and the duration of its source time function is set to 3.1s referring to the waveform fitting at the rock stations outside the basin. In the previous studies for the Osaka basin (Horikawa et al., 2003; Kawabe and Kamae, 2006; Iwaki and Iwata, 2011), Q0 at a reference period T0 is given by a function of S-wave velocity; Q0=αVs. We fixed T0 at 5s, and tested Q0 value changing α from 0.1 to 1.0. Comparing the envelope of synthetic velocity waveforms with that of observed waveforms in the basin, α of 0.3 fits to the observation well, whereas the difference from 0.2 to 0.5 is not significant. The simulation explains the characteristics of observed seismic waves propagating inside the basin in terms of duration and amplitude at most stations. The response velocity spectra and dominant period would be demonstrated to see the areal performance of present velocity model (UMC2013), and we will discuss how later phases generates and propagates based on the simulated wave field. Acknowledgements: We used strong motion data from K-NET/KiK-net, JMA, Osaka Prefectural Government, BRI, and CEORKA.

Paleomagnetism of baked sedimentary rocks in the Newark and Culpeper basins: Evidence for the J1 cusp and significant Late Triassic apparent polar wander from the Mesozoic basins of North America

NASA Astrophysics Data System (ADS)

Kodama, Kenneth P.; Cioppa, Maria T.; Sherwood, Elizabeth; Warnock, Andrew C.

1994-08-01

A paleomagnetic study of 14 sites in the baked sedimentary rocks of the Newark basin Passaic Formation in southeastern Pennsylvania reveals two types of magnetic behavior. Dark gray-colored, baked sedimentary rocks have peak unblocking temperatures of 640°C, high magnetic intensities, and shallow, normal polarity, northeasterly directions. Light gray-colored rocks have peak unblocking temperatures of less than 580°C, low magnetic intensities, and intermediate inclination, normal polarity, northwesterly directions. The low unblocking temperature magnetizations are secondary magnetizations which have declinations similar to but are shallower than the B remagnetization observed by Witte and Kent (1991) throughout the Newark basin. The discrepancy may be due to "underprinting" by an unresolved primary magnetization. The low unblocking temperature magnetization was probably acquired by growth of secondary magnetite during a hydrothermal event, as postulated by Sutter (1988), based on geochronologic data. The high unblocking temperature magnetization is significantly prefolding. Both the low-peak unblocking temperature magnetization and the high-peak unblocking temperature magnetization suggest a 15° counterclockwise block rotation of the Sassamansville syncline. If this rotation is removed from the high unblocking temperature sites collected around the fold, a stronger passage of the fold test results. Six sites were also collected from baked sediments and one site from diabase in northern Virginia's Culpeper basin, since Sutter's geochronological work indicated that the intrusives in the Culpeper basin are coeval to the Newark basin intrusives. Virtual geomagnetic poles (VGPs), based on the tilt-corrected, high-temperature Newark basin magnetizations, were compared with the VGPs calculated from the site means of a high-temperature magnetization isolated from baked sedimentary rocks in the Culpeper basin and to the magnetizations reported by Raymond (1982) from dikes and sills. In this comparison the in situ Culpeper poles agreed with the prefolding Newark poles significantly better than the prefolding Culpeper poles. This result indicates that Culpeper intrusives erupted into already tilted sedimentary rocks. The paleomagnetic pole determined from the combined Culpeper baked sediments, dikes, and sills (in situ coordinates) and the Newark basin baked sediments (tilt-corrected coordinates) lies at 60°N, 69°E and is of 201 Ma age. This latest Triassic/earliest Jurassic pole, when combined with the Newark basin Carnian results (Witte and Kent, 1989) and Norian results (Witte et al., 1991) corrected for a counterclockwise block rotation (Kodama et al., 1994), provides a record of significant polar wander from eastern North America's Mesozoic basins for the Late Triassic. This is consistent with observations made for a similar time period from rocks on the Colorado Plateau (Bazard and Butler, 1991). Comparison of the Newark/Culpeper pole to similar age poles from the Kayenta (Bazard and Butler, 1991) and Moenave Formations (Ekstrand and Butler, 1989) only requires small amounts (5°) of Colorado Plateau rotation. The pole also provides the first well-dated evidence of the Jl cusp in North American apparent polar wander from rocks not located on the Colorado Plateau, thus giving strong support for the usefulness of paleomagnetic Euler pole analysis of apparent polar wander.

Sedimentary facies and depositional environments of early Mesozoic Newark Supergroup basins, eastern North America

USGS Publications Warehouse

Smoot, J.P.

1991-01-01

The early Mesozoic Newark Supergroup consists of continental sedimentary rocks and basalt flows that occupy a NE-trending belt of elongate basins exposed in eastern North America. The basins were filled over a period of 30-40 m.y. spanning the Late Triassic to Early Jurassic, prior to the opening of the north Atlantic Ocean. The sedimentary rocks are here divided into four principal lithofacies. The alluvial-fan facies includes deposits dominated by: (1) debris flows; (2) shallow braided streams; (3) deeper braided streams (with trough crossbeds); or (4) intense bioturbation or hyperconcentrated flows (tabular, unstratified muddy sandstone). The fluvial facies include deposits of: (1) shallow, ephemeral braided streams; (2) deeper, flashflooding, braided streams (with poor sorting and crossbeds); (3) perennial braided rivers; (4) meandering rivers; (5) meandering streams (with high suspended loads); (6) overbank areas or local flood-plain lakes; or (7) local streams and/or colluvium. The lacustrine facies includes deposits of: (1) deep perennial lakes; (2) shallow perennial lakes; (3) shallow ephemeral lakes; (4) playa dry mudflats; (5) salt-encrusted saline mudflats; or (6) vegetated mudflats. The lake margin clastic facies includes deposits of: (1) birdfoot deltas; (2) stacked Gilbert-type deltas; (3) sheet deltas; (4) wave-reworked alluvial fans; or (5) wave-sorted sand sheets. Coal deposits are present in the lake margin clastic and the lacustrine facies of Carnian age (Late Triassic) only in basins of south-central Virginia and North and South Carolina. Eolian deposits are known only from the basins in Nova Scotia and Connecticut. Evaporites (and their pseudomorphs) occur mainly in the northern basins as deposits of saline soils and less commonly of saline lakes, and some evaporite and alkaline minerals present in the Mesozoic rocks may be a result of later diagenesis. These relationships suggest climatic variations across paleolatitudes, more humid to the south where coal beds are preserved, and more arid in the north where evaporites and eolian deposits are common. Fluctuations in paleoclimate that caused lake levels to rise and fall in hydrologically closed basins are preserved as lacustrine cycles of various scales, including major shifts in the Late Triassic from a wet Carnian to an arid Norian. In contrast, fluvial deposits were mainly formed in response to the tectonic evolution of the basins, but to some extent also reflect climatic changes. The Newark Supergroup illustrates the complexity of rift-basin sedimentation and the problems that may arise from using a single modern analog for sedimentary deposition spanning millions of years. It also shows that a tremendous wealth of depositional, climatic, and tectonic information is preserved in ancient rift-basin deposits which can be recovered if the depositional processes of modern rift-basin deposits are understood. ?? 1991.

Stratigraphic framework and evolution of the Cretaceous continental sequences of the Bauru, Sanfranciscana, and Parecis basins, Brazil

NASA Astrophysics Data System (ADS)

Batezelli, Alessandro; Ladeira, Francisco Sergio Bernardes

2016-01-01

With the breakup of the supercontinent Gondwana, the South American Plate has undergone an intense process of tectonic restructuring that led to the genesis of the interior basins that encompassed continental sedimentary sequences. The Brazilian Bauru, Sanfranciscana and Parecis basins during Late Cretaceous have had their evolution linked to this process of structuring and therefore have very similar sedimentary characteristics. The purpose of this study is to establish a detailed understanding of alluvial sedimentary processes and architecture within a stratigraphic sequence framework using the concept of the stratigraphic base level or the ratio between the accommodation space and sediment supply. The integration of the stratigraphic and facies data contributed to defining the stratigraphic architecture of the Bauru, Sanfranciscana and Parecis Basins, supporting a model for continental sequences that depicts qualitative changes in the sedimentation rate (S) and accommodation space (A) that occurred during the Cretaceous. This study discusses the origin of the unconformity surfaces (K-0, K-1 and K-1A) that separate Sequences 1, 2A and 2B and the sedimentary characteristics of the Bauru, Sanfranciscana and Parecis Basins from the Aptian to the Maastrichtian, comparing the results with other Cretaceous Brazilian basins. The lower Cretaceous Sequence 1 (Caiuá and Areado groups) is interpreted as a low-accommodation systems tract compound by fluvial and aeolian systems. The upper Cretaceous lacustrine, braided river-dominated alluvial fan and aeolian systems display characteristics of the evolution from high-to low-accommodation systems tracts (Sequences 2A and 2B). Unconformity K-0 is related to the origin of the Bauru Basin itself in the Early Cretaceous. In Sanfranciscana and Parecis basins, the unconformity K-0 marks the contact between aeolian deposits from Lower Cretaceous and Upper Cretaceous alluvial systems (Sequences 1 and 2). Unconformity K-1, which was generated in the Late Cretaceous, is related to an increase of the A/S ratio, whereas Unconformity K-1A is the result of the decrease in the A/S ratio. Unconformity K-1A bound Sequence 2A (lacustrine and fluvial systems) and Sequence 2B (alluvial deposits) in Bauru Basin whereas in the Sanfranciscana and Parecis basins this unconformity marks the transition from alluvial system to aeolian system (Sequences 2A and 2B). Changes in depositional style in both basins correspond to two distinct tectonic moments occurring within the South American plate. The first associated with post-volcanic thermal subsidence of the Early Cretaceous (Serra Geral and Tapirapuã volcanismos), and the second moment associated with the uplift occurred in the Late Cretaceous (Alto Paranaíba, Vilhena and Serra Formosa Arcs).

Importance of lithology in defining natural background concentrations of Cr, Cu, Ni, Pb and Zn in sedimentary soils, northeastern Brazil.

PubMed

Gloaguen, Thomas Vincent; Passe, José João

2017-11-01

The sedimentary basins of Recôncavo and Tucano, Bahia, represent the most important Brazilian Phanerozoic continental basin system, formed during fracturing of Gondwana. The northern basin of Tucano has a semiarid climate (Bsh) while the southern basin of Recôncavo has a tropical rainforest climate (Af). The aim of this study was to determine the distribution of trace metals in soils derived from various sedimentary rocks and climates. Soils were collected at 30 sites in 5 geological units at 0-20 cm and 60-80 cm deep under native vegetation. Physical and chemical attributes (particle size distribution, pH, Al, exchangeable bases, organic matter) were determined, as well as the pseudo-total concentrations (EPA 3050 b) and the total concentrations (X-ray fluorescence) of Cr, Cu, Ni, Pb and Zn. The concentrations of metals were overall correlated to soil texture, according to lithologic origin. Shales resulted in Vertisols 30.4 (Zn), 27.2 (Ni), 16.9 (Cu), 7.5 (Cr) and 2.5 (Pb) times more concentrated than Arenosols derived from the sandstones. High Cr and Ni values in clay soils from shales were attributed to diffuse contamination by erosion of mafic rocks of the Greenstone Belt River Itapicuru (from 3 km northwest of the study area) during the late Jurassic. Tropical rainforest climate resulted in a slight enrichment of Pb and Cr, and Ni had the higher mobility during soil formation (enrichment factor up to 6.01). In conclusion, the geological environment is a much more controlling factor than pedogenesis in the concentration of metals in sedimentary soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Empirical relations of rock properties of outcrop and core samples from the Northwest German Basin for geothermal drilling

NASA Astrophysics Data System (ADS)

Reyer, D.; Philipp, S. L.

2014-09-01

Information about geomechanical and physical rock properties, particularly uniaxial compressive strength (UCS), are needed for geomechanical model development and updating with logging-while-drilling methods to minimise costs and risks of the drilling process. The following parameters with importance at different stages of geothermal exploitation and drilling are presented for typical sedimentary and volcanic rocks of the Northwest German Basin (NWGB): physical (P wave velocities, porosity, and bulk and grain density) and geomechanical parameters (UCS, static Young's modulus, destruction work and indirect tensile strength both perpendicular and parallel to bedding) for 35 rock samples from quarries and 14 core samples of sandstones and carbonate rocks. With regression analyses (linear- and non-linear) empirical relations are developed to predict UCS values from all other parameters. Analyses focus on sedimentary rocks and were repeated separately for clastic rock samples or carbonate rock samples as well as for outcrop samples or core samples. Empirical relations have high statistical significance for Young's modulus, tensile strength and destruction work; for physical properties, there is a wider scatter of data and prediction of UCS is less precise. For most relations, properties of core samples plot within the scatter of outcrop samples and lie within the 90% prediction bands of developed regression functions. The results indicate the applicability of empirical relations that are based on outcrop data on questions related to drilling operations when the database contains a sufficient number of samples with varying rock properties. The presented equations may help to predict UCS values for sedimentary rocks at depth, and thus develop suitable geomechanical models for the adaptation of the drilling strategy on rock mechanical conditions in the NWGB.

Supercritical bedforms and sedimentary structures from field and core studies, Middle Eocene deep-marine base-of-slope environment, Ainsa Basin, Spanish Pyrenees

NASA Astrophysics Data System (ADS)

Cornard, Pauline; Pickering, Kevin

2017-04-01

In recent years, many researchers have focussed on supercritical- and subcritical-flow deposits using flume-tank experiments (e.g., Cartigny el al., 2011; Postma et al., 2014; Postma and Cartigny, 2014), or from direct observations on presently active deep-water systems (e.g., Hughes et al., 2012). Using outcrop and core examples from a base-of-slope environment in the Middle Eocene Ainsa Basin, Spanish Pyrenees, and with published experimental work, a range of deposits are interpreted as upper-flow regime sedimentary structures. This contribution focusses on the interpretation of several supercritical bedforms (antidunes and chutes-and-pools) observed on the field and upper-flow regime sedimentary structures recognized in cores. The spatial distribution of supercritical-flow deposits obtained from an analysis of field outcrops and core sedimentary logs are evaluated in relation to the depositional environment (channel axis, off-axis, margin and interfan). The frequency distributions of the bed thicknesses are also analysed in relation to supercritical versus subcritical bed-thickness distributions.

Structure of the Tucson Basin, Arizona from gravity and aeromagnetic data

USGS Publications Warehouse

Rystrom, Victoria Louise

2003-01-01

Interpretation of gravity and high-resolution aeromagnetic data reveal the three-dimensional geometry of the Tuscson Basin, Arizona and the lithology of its basement. Limited drill hole and seismic data indicate that the maximum depth to the crystalline basement is approximately 3600 meters and that the sedimentary sequences in the upper ~2000 m of the basin were deposited during the most recent extensional episode that commenced about 13 Ma. The negative density contrasts between these upper Neogene and Quaternary sedimentary sequences and the adjacent country rock produce a Bouguer residual gravity low, whose steep gradients clearly define the lateral extent of the upper ~2000m of the basin. The aeromagnetic maps show large positive anomalies associated with deeply buried, late Cretaceous-early Tertiary and mid-Tertiary igneous rocks at and below the surface of the basin. These magnetic anomalies provide insight into the older (>13 Ma) and deeper structures of the basin. Simultaneous 2.5-dimensional modeling of both gravity and magnetic anomalies constrained by geologic and seismic data delineates the thickness of the basin and the dips of the buried faults that bound the basin. This geologic-based forward modeling approach to using geophysical data is shown to result in more information about the geologic and tectonic history of the basin as well as more accurate depth to basement determinations than using generalized geophysical inversion techniques.

North European Transect

NASA Astrophysics Data System (ADS)

Korja, Annakaisa; Heikkinen, Pekka J.; Roslov, Yuri; Ivanova, Nina; Verba, Marc; Sakoulina, Tamara

2010-05-01

A nearly continuous, 3600 km long, NE-running North European Transect (NET) is combined from the existing deep seismic reflection data sets in the Baltic Sea (BABEL, 1600 km), Northern Finland (FIRE 4-4A, 580 km) and Barents Sea (1-AR, 1440 km;). The reflective image of the deep crust is highly dependent on the thickness of the sedimentary cover. The cover is few hundred meters in the Baltic sea, few tens of meters in the land areas and few kilometers in the Barents Sea area. In the Barents Sea area, the seismic image is dominated by the layered structure of the sedimentary basins and the middle and lower crust are poorly imaged. Therefore the Moho boundary in the Barents Sea has been determined from wide-angle reflections. Geologically the transect covers the transition from Phanerozoic Europe to Precambrian Europe and back to the Phanerozoic Barents Sea Shelf. It displays how Northern Europe grew around Baltica in several tectonic episodes involving the formation and destruction of Columbia/Hudsonland, Rodinia and Pangea supercontinents. The paleo plateboundaries are traversed by subvertical transparent zones suggesting transpressional and trantensional environments. The BABEL lines image how the core of Baltica was formed by sequential accretion of microcontinents and arc terranes at the old continental margin during the Svecofennian Orogeny ~1.9-1.8 Ga .When Baltica joined the Columbia supercontinent, new terranes were added to its southern edge in the Sveocbaltic Orogeny (~1.8 Ga). During the dispersal of the Columbia, the Baltic Sea failed rift was formed, rapakivi granitoids were intruded and sedimentary basins were developed. An extended plate margin structure has been imposed on the Rodinian (Sveconorwegian) and Pangean additions (Variscan-Caledonian). Major crustal thinning takes place along a series of subvertical faults across the Trans-European Suture Zone marking the transition from Phanerozoic to Proterozoic Europe. The FIRE lines in Northen Finland image a collage of older continental fragments and intervening basins that have been welded together in Svecofennian and Lapland-Kola orogenies. The Lapland-Kola orogen record the collision of Baltica and Laurentia during the compilation of the Columbia supercontinent. The collisional structures were overprinted by extension associated with the dispersal of Columbia. The Russian Arctic line 1-AR focuses on the Phanerozoic sedimentary cover of the Barents Sea Basin. The line images the transition from Paleoproterozoic Baltica to Neoproterozoic Barentsia. As part of the Rodinia supercontinent formation, Baltica collided with Barentsia resulting in Timanide orogeny. During the break-up of Rodinia an aborted rift was formed within the Barentsia. Later peripheral tectonic events modified the interior parts of Barentsia that acted first as a back arc basin and later as a foreland basin to the Uralian and Caledonian orogen during the formation of the Pangea supercontinent.

Structuring and evolution of Neogene transcurrent basins in the Tellian foreland domain, north-eastern Tunisia

NASA Astrophysics Data System (ADS)

Melki, Fetheddine; Zouaghi, Taher; Harrab, Salah; Sainz, Antonio Casas; Bédir, Mourad; Zargouni, Fouad

2011-07-01

The Neogene sedimentary basins (Serravallian to Quaternary) of the Tellian tectonic foreland in north-eastern Tunisia formed within the overall NE-SW sinistral strike-slip tectonic framework of the Ras El Korane-Thibar and El Alia-Teboursouk fault systems. From stratigraphic logs, structural cross sections and interpretation of 2D seismic lines and boreholes, the pre-Neogene basement can be interpreted to be structured according to Eocene (NW-SE) compressional and Oligocene extensional phases. This basement comprises structural highs (anticlines and horsts) and subsiding areas (synclines, half-grabens and grabens) formed during the Neogene. The subsiding areas are delineated by faults striking N030E, N-S and N140E, defining (i) narrow, strongly subsiding synclines, (ii) lozenge-shaped basins and (iii) trapezoidal basins. The architecture of their fill results from the sedimentary balance between tectonics and eustatism. Halokinesis and clay diapirism (driven by Triassic and Neogene evaporites and clays) also played an important role in basin evolution, contributing to the formation of domes and diapirs along active faults.

An evaluation of the suitability of ERTS data for the purposes of petroleum exploration. [Anadarko Basin of Texas and Oklahoma

NASA Technical Reports Server (NTRS)

Collins, R. J.; Mccown, F. P.; Stonis, L. P.; Petzel, G.; Everett, J. R.

1974-01-01

This experiment was designed to determine the types and amounts of information valuable to petroleum exploration extractable from ERTS data and the cost of obtaining the information using traditional or conventional means. It was desired that an evaluation of this new petroleum exploration tool be made in a geologically well known area in order to assess its usefulness in an unknown area. The Anadarko Basin lies in western Oklahoma and the panhandle of Texas. It was chosen as a test site because there is a great deal of published information available on the surface and subsurface geology of the area, and there are many known structures that act as traps for hydrocarbons. This basin is similar to several other large epicontinental sedimentary basins. It was found that ERTS imagery is an excellent tool for reconnaissance exploration of large sedimentary basins or new exploration provinces. For the first time, small and medium size oil companies can rapidly and effectively analyze exploration provinces as a whole.

The Paleozoic - Mesozoic Mekele Sedimentary Basin in Ethiopia: An example of an exhumed IntraCONtinental Sag (ICONS) basin

NASA Astrophysics Data System (ADS)

Alemu, Tadesse; Abdelsalam, Mohamed G.; Dawit, Enkurie L.; Atnafu, Balemwal; Mickus, Kevin L.

2018-07-01

We investigated the evolution of the Mekele Sedimentary Basin (MSB) in northern Ethiopia using geologic field and gravity data. The depth to Moho and lithospheric structure beneath the basin was imaged using two-dimensional (2D) radially-averaged power spectral analysis, Lithoflex three-dimensional (3D) forward and inverse modeling, and 2D forward modeling of the Bouguer gravity anomalies. Previous studies proposed that the basin was formed as part of a multi-branched rift system related to the breakup of Gondwana. Our results show that the MSB: (1) is circular to elliptical in map view and saucer shaped in cross sectional view, (2) is filled with terrestrial and shallow marine sedimentary rocks, (3) does not significantly structurally control the sedimentation and the major faults are post-depositional, (4) is characterized by a concentric gravity minima, (5) is underlain by an unstretched crust (∼40 km thick) and thicker lithosphere (∼120 km thick). These features compare positively with a group of basins known as IntraCONtinental Sags (ICONS), especially those ICONS formed over accretionary orogenic terranes. Since the MSB is located above the Neoproterozoic accretionary orogenic terranes of the Arabian-Nubian Shield (ANS), we propose that the formation of the MSB to be related to cooling and thickening of a juvenile sub-continental lithospheric mantle beneath the ANS, which most probably provided negative buoyancy, and hence subsidence in the MSB, leading to its formation as an ICONS. The MSB could be used as an outcrop analog for information about the internal facies architecture of ICONS because it is completely exhumed due to tectonic uplift on the western flank of the Afar Depression.

Coal-bed gas resources of the Rocky Mountain region

USGS Publications Warehouse

Schenk, C.J.; Nuccio, V.F.; Flores, R.M.; Johnson, R.C.; Roberts, S.B.; Collett, T.S.

2001-01-01

The Rocky Mountain region contains several sedimentary provinces with extensive coal deposits and significant accumulations of coal-bed gas. This summary includes coal-bed gas resources in the Powder River Basin (Wyoming and Montana), Wind River Basin (Wyoming), Southwest Wyoming (Greater Green River Basin of Wyoming, Colorado, and Utah), Uinta-Piceance Basin (Colorado and Utah), Raton Basin (Colorado and New Mexico), and San Juan Basin (Colorado and New Mexico). Other provinces in the Rocky Mountain region may contain significant coal-bed gas resources, but these resource estimates are not available at this time.

Petroleum geology and resource assessment of the Timan-Pechora Basin, USSR, and the adjacent Barents-northern Kara shelf

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ulmishek, G.

1982-06-01

The regions discussed contain thick sequences of sedimentary rocks ranging in age from early Paleozoic to Late Cretaceous and, occasionally, Cenozoic. Over 50 oil and gas fields, including two giants, are found in the Timan-Pechora Basin. The Barents-northern Kara shelf is still in the earliest stage of exploration. This report considers (1) tectonic regionalization of the Timan-Pechora Basin and major structures in each region; (2) facies characteristics of the sedimentary cover and the history of geological development; (3) the main hydrogeological features; (4) producing regions of each basin and the major oil and gas fields; (5) specificity of oil-gas generationmore » and formation of fields; and (6) geology and conditions for expected productivity of the Barents-northern Kara shelf. Initial recoverable petroleum resources of the Timan-Pechora basin are estimated at 0.86 x 10/sup 9/ t (6.4 x 10/sup 9/ bbl) of oil and 1.7 x 10/sup 12/ m/sup 3/ (60 TCF) of gas, of which 0.41 x 10/sup 9/ t (3.0 x 10/sup 9/ bbl) of oil and 1.2 x 10/sup 12/ m/sup 3/ (42 TCF) of gas are yet to be discovered. Potential recoverable resources of the Barents-northern Kara shelf are estimated at 3.2 x 10/sup 9/ t (23.7 x 10/sup 9/ bbl) of oil and 10.2 x 10/sup 12/ m/sup 3/ (360 TCF) of gas.« less

Architecture of buried reverse fault zone in the sedimentary basin: A case study from the Hong-Che Fault Zone of the Junggar Basin

NASA Astrophysics Data System (ADS)

Liu, Yin; Wu, Kongyou; Wang, Xi; Liu, Bo; Guo, Jianxun; Du, Yannan

2017-12-01

It is widely accepted that the faults can act as the conduits or the barrier for oil and gas migration. Years of studies suggested that the internal architecture of a fault zone is complicated and composed of distinct components with different physical features, which can highly influence the migration of oil and gas along the fault. The field observation is the most useful methods of observing the fault zone architecture, however, in the petroleum exploration, what should be concerned is the buried faults in the sedimentary basin. Meanwhile, most of the studies put more attention on the strike-slip or normal faults, but the architecture of the reverse faults attracts less attention. In order to solve these questions, the Hong-Che Fault Zone in the northwest margin of the Junggar Basin, Xinjiang Province, is chosen for an example. Combining with the seismic data, well logs and drill core data, we put forward a comprehensive method to recognize the internal architectures of buried faults. High-precision seismic data reflect that the fault zone shows up as a disturbed seismic reflection belt. Four types of well logs, which are sensitive to the fractures, and a comprehensive discriminated parameter, named fault zone index are used in identifying the fault zone architecture. Drill core provides a direct way to identify different components of the fault zone, the fault core is composed of breccia, gouge, and serpentinized or foliated fault rocks and the damage zone develops multiphase of fractures, which are usually cemented. Based on the recognition results, we found that there is an obvious positive relationship between the width of the fault zone and the displacement, and the power-law relationship also exists between the width of the fault core and damage zone. The width of the damage zone in the hanging wall is not apparently larger than that in the footwall in the reverse fault, showing different characteristics with the normal fault. This study provides a comprehensive method in identifying the architecture of buried faults in the sedimentary basin and would be helpful in evaluating the fault sealing behavior.

Magnetic Basement Depth Inversion in the Space Domain

NASA Astrophysics Data System (ADS)

Nunes, Tiago Mane; Barbosa, Valéria Cristina F.; Silva, João Batista C.

2008-10-01

We present a total-field anomaly inversion method to determine both the basement relief and the magnetization direction (inclination and declination) of a 2D sedimentary basin presuming negligible sediment magnetization. Our method assumes that the magnetic intensity contrast is constant and known. We use a nonspectral approach based on approximating the vertical cross section of the sedimentary basin by a polygon, whose uppermost vertices are forced to coincide with the basin outcrop, which are presumably known. For fixed values of the x coordinates our method estimates the z coordinates of the unknown polygon vertices. To obtain the magnetization direction we assume that besides the total-field anomaly, information about the basement’s outcrops at the basin borders and the basement depths at a few points is available. To obtain stable depth-to-basement estimates we impose overall smoothness and positivity constraints on the parameter estimates. Tests on synthetic data showed that the simultaneous estimation of the irregular basement relief and the magnetization direction yields good estimates for the relief despite the mild instability in the magnetization direction. The inversion of aeromagnetic data from the onshore Almada Basin, Brazil, revealed a shallow, eastward-dipping basement basin.

Sedimentary Cover of the Central Arctic

NASA Astrophysics Data System (ADS)

Kireev, Artem; Poselov, Viktor; Butsenko, Viktor; Smirnov, Oleg

2017-04-01

Partial revised Submission of the Russian Federation for establishment of the OLCS (outer limit of the continental shelf) in the Arctic Ocean is made to include in the extended continental shelf of the Russian Federation, in accordance with article 76 of the Convention, the seabed and its subsoil in the central Arctic Ocean which is natural prolongation of the Russian land territory. To submit partial revised Submission in 2016, in 2005 - 2014 the Russian organizations carried out a wide range of geophysical studies, so that today over 23000 km of MCS lines, over hundreds of wide-angle reflection/refraction seismic sonobuoy soundings and 4000 km of deep seismic sounding are accomplished. All of these MCS and seismic soundings data were used to establish the seismic stratigraphy model of the Arctic region. Stratigraphy model of the sedimentary cover was successively determined for the Cenozoic and pre-Cenozoic parts of the section and was based on correlation of the Russian MCS data and seismic data documented by existing boreholes. Interpretation of the Cenozoic part of the sedimentary cover was based on correlation of the Russian MCS data and AWI91090 section calibrated by ACEX-2004 boreholes on the Lomonosov Ridge for Amerasia basin and by correlation of onlap contacts onto oceanic crust with defined magnetic anomalies for Eurasia basin, while interpretation of the Pre-Cenozoic part of the sedimentary cover was based on correlation with MCS and boreholes data from Chukchi sea shelf. Six main unconformities were traced: regional unconformity (RU), Eocene unconformity (EoU) (for Eurasia basin only), post-Campanian unconformity (pCU), Brookian (BU - base of the Lower Brookian unit), Lower Cretaceous (LCU) and Jurassic (JU - top of the Upper Ellesmerian unit). The final step in our research was to estimate the total thickness of the sedimentary cover of the Arctic Ocean and adjacent Eurasian shelf using top of acoustic basement correlation data and bathymetry data. Structural prolongation of the shallow shelf into deep-water could be observed on this sedimentary map.

Quantitative characterisation of sedimentary grains

NASA Astrophysics Data System (ADS)

Tunwal, Mohit; Mulchrone, Kieran F.; Meere, Patrick A.

2016-04-01

Analysis of sedimentary texture helps in determining the formation, transportation and deposition processes of sedimentary rocks. Grain size analysis is traditionally quantitative, whereas grain shape analysis is largely qualitative. A semi-automated approach to quantitatively analyse shape and size of sand sized sedimentary grains is presented. Grain boundaries are manually traced from thin section microphotographs in the case of lithified samples and are automatically identified in the case of loose sediments. Shape and size paramters can then be estimated using a software package written on the Mathematica platform. While automated methodology already exists for loose sediment analysis, the available techniques for the case of lithified samples are limited to cases of high definition thin section microphotographs showing clear contrast between framework grains and matrix. Along with the size of grain, shape parameters such as roundness, angularity, circularity, irregularity and fractal dimension are measured. A new grain shape parameter developed using Fourier descriptors has also been developed. To test this new approach theoretical examples were analysed and produce high quality results supporting the accuracy of the algorithm. Furthermore sandstone samples from known aeolian and fluvial environments from the Dingle Basin, County Kerry, Ireland were collected and analysed. Modern loose sediments from glacial till from County Cork, Ireland and aeolian sediments from Rajasthan, India have also been collected and analysed. A graphical summary of the data is presented and allows for quantitative distinction between samples extracted from different sedimentary environments.

When did the Penglai orogeny begin on Taiwan?: Geochronological and petrographic constraints on the exhumed mountain belts and foreland-basin sequences

NASA Astrophysics Data System (ADS)

Chen, W. S.; Syu, S. J.; Yeh, J. J.

2017-12-01

Foreland basin receives large amounts of synorogenic infill that is eroded from the adjacent exhumed mountain belt, and therefore provides the important information on exhumation evolution. Furthermore, a complete stratigraphic sequence of Taiwan mountain belt consists of five units of Miocene sedimentary rocks (the Western Foothills and the uppermost sequence on the proto-Taiwan mountain belt), Oligocene argillite (the Hsuehshan Range), Eocene quartzite (the Hsuehshan Range), Eocene-Miocene slate and schist (Backbone Range), and Cretaceous schist (Backbone Range) from top to bottom. Based on the progressive unroofing history, the initiation of foreland basin received sedimentary lithic sediments from the uppermost sequence of proto-Taiwan mountain belt, afterwards, and receiving low- to medium-grade metamorphic lithic sediments in ascending order of argillite, quartzite, slate, and schist clasts. Therefore, the sedimentary lithics from mountain belt were deposited which represents the onset of the mountain uplift. In this study, the first appearance of sedimentary lithic sediments occurs in the Hengchun Peninsula at the middle Miocene (ca. 12-10 Ma). Thus, sandstone petrography of the late Miocene formation (10-5.3 Ma) shows a predominantly recycled sedimentary and low-grade metamorphic sources, including sandstone, argillite and quartzite lithic sediments of 10-25% which records erosion to slightly deeper metamorphic terrane on the mountain belt. Based on the results of previous thermogeochronological studies of the Yuli belt, it suggests that the middle Miocene occurred mountain uplift. The occurrence of low-grade metamorphic lithic sediments in the Hengchun Peninsula during late Miocene is coincident with the cooling ages of uplift and denuded Yuli schist belt at the eastern limb of Backbone Range.

Heat flow, deep formation temperature and thermal structure of the Tarim Basin, northwest China

NASA Astrophysics Data System (ADS)

Liu, Shaowen; Lei, Xiao; Feng, Changge; Li, Xianglan

2016-04-01

Geothermal regime of a sedimentary basin not only provides constraint on understanding the basin formation and evolution, but also offers fundamental parameters for hydrocarbon resources assessment. As one of three Precambrian blocks in China, the Tarim craton is also a current hydrocarbon exploration target where the largest sedimentary basin (Tarim Basin) develops with great potential. Although considerable advancement of geothermal regime of this basin has been made during the past decades, nearly all the temperature data in previous studies are from the exploration borehole formation testing temperatures. Recently, we have conducted the steady-state temperature logging in the Tarim basin, and measured abundant rock thermal properties, enabling us to re-visit the thermal regime of this area with more confidence. Our results show that the present-day geothermal gradients for the Tarim Basin vary from 23 K/km to 27 K/km, with a mean of 22 K/km; the values of heat flow range from 40 mW/m2 to 49 mW/m2, with a mean of 43 mW/m2. These new data confirmed that the Tarim Basin has relatively low heat flow and shares similar geothermal regime with other Precambrian cratons in the world. In addition, the new temperatures from the steady-state logs are larger than the bottom hole temperatures (BHT) as 22 degree Celsius, indicating the thermal non-equilibrium for the BHTs used in previous studies. Spatial distribution of the estimated formation temperatures-at-depth of 1~5km within the basin is similar and mainly controlled by crystalline basement pattern. Generally, the temperatures at the depth of 1km range from 29 to 41 degree Celsius, with a mean of 35 degree Celsius; while the temperatures at 3km vary from 63 to 100 degree Celsius, and the mean is 82 degree Celsius; at 5km below the surface, the temperatures fall into a range between 90 and 160 degree Celsius, with a mean of 129 degree Celsius. We further proposed the long-term low geothermal background and large burial depth are the favorable conditions for hydrocarbon generation and preservation. As far as heat budget of the Tarim Basin is concerned, the radiogenic heat from the sedimentary cover accounts only for 20 percent of the surface heat flow (~9 mW/m2), while the mantle heat flow is estimated to be low as 6~15 mW/m2; this indicates the dominant contribution of crustal radiogenic heat to the observed heat flow. Any variations in surface heat flow for the Tarim Basin can be due only to changes in crustal heat production. Thermal contrast between the Tarim Basin and Tibet Plateau, represented by a difference in surface heat flow and deep crustal temperature, is remarkable. This inherited thermal contrast can be traced as far as before the India-Asia collision. Moreover, the lithosphere beneath the Tarim Basin is sufficiently strong to resist the gravitational potential energy difference and tectonic forces from Tibet. The observed thermal and rheological contrast accounts for the differential Cenozoic deformation in the Tarim Basin and adjacent areas.

Hydrogeologic framework and selected components of the groundwater budget for the upper Umatilla River Basin, Oregon

USGS Publications Warehouse

Herrera, Nora B.; Ely, Kate; Mehta, Smita; Stonewall, Adam J.; Risley, John C.; Hinkle, Stephen R.; Conlon, Terrence D.

2017-05-31

Executive SummaryThis report presents a summary of the hydrogeology of the upper Umatilla River Basin, Oregon, based on characterization of the hydrogeologic framework, horizontal and vertical directions of groundwater flow, trends in groundwater levels, and components of the groundwater budget. The conceptual model of the groundwater flow system integrates available data and information on the groundwater resources of the upper Umatilla River Basin and provides insights regarding key hydrologic processes, such as the interaction between the groundwater and surface water systems and the hydrologic budget.The conceptual groundwater model developed for the study area divides the groundwater flow system into five hydrogeologic units: a sedimentary unit, three Columbia River basalt units, and a basement rock unit. The sedimentary unit, which is not widely used as a source of groundwater in the upper basin, is present primarily in the lowlands and consists of conglomerate, loess, silt and sand deposits, and recent alluvium. The Columbia River Basalt Group is a series of Miocene flood basalts that are present throughout the study area. The basalt is uplifted in the southeastern half of the study area, and either underlies the sedimentary unit, or is exposed at the surface. The interflow zones of the flood basalts are the primary aquifers in the study area. Beneath the flood basalts are basement rocks composed of Paleogene to Pre-Tertiary sedimentary, volcanic, igneous, and metamorphic rocks that are not used as a source of groundwater in the upper Umatilla River Basin.The major components of the groundwater budget in the upper Umatilla River Basin are (1) groundwater recharge, (2) groundwater discharge to surface water and wells, (3) subsurface flow into and out of the basin, and (4) changes in groundwater storage.Recharge from precipitation occurs primarily in the upland areas of the Blue Mountains. Mean annual recharge from infiltration of precipitation for the upper Umatilla River Basin during 1951–2010 is about 9.6 inches per year (in/yr). Annual recharge from precipitation for water year 2010 ranged from 3 in. in the lowland area to about 30 in. in the Blue Mountains. Using Kahle and others (2011) data and methods from the Columbia Plateau regional model, average annual recharge from irrigation is estimated to be about 2.2 in/yr for the 13 square miles of irrigated land in the upper Umatilla River Basin.Groundwater discharges to streams throughout the year and is a large component of annual streamflow in the upper Umatilla River Basin. Upward vertical hydraulic gradients near the Umatilla River indicate the potential for groundwater discharge. Groundwater discharge to the Umatilla River generally occurs in the upper part of the basin, upstream from the main stem.Groundwater development in the upper Umatilla River Basin began sometime after 1950 (Davies-Smith and others, 1988; Gonthier and Bolke, 1991). By water year 2010, groundwater use in the upper Umatilla River Basin was approximately 11,214 acre-feet (acre-ft). Total groundwater withdrawals for the study area were estimated at 7,575 acre-ft for irrigation, 3,173 acre-ft for municipal use, and 466 acre-ft for domestic use.Total groundwater flow into or from the study area depends locally on geology and hydraulic head distribution. Estimates of subsurface flow were calculated using the U.S. Geological Survey Columbia Plateau regional groundwater flow model. Net flux values range from 25,000 to 27,700 acre-ft per year and indicate that groundwater is moving out of the upper Umatilla River Basin into the lower Umatilla River Basin.Water level changes depend on storage changes within an aquifer, and storage changes depend on the storage properties of the aquifer, as well as recharge to or discharge from the aquifer. Groundwater level data in the upper Umatilla River Basin are mostly available from wells in Columbia River basalt units, which indicate areas of long-term water level declines in the Grande Ronde basalt unit near Pendleton and Athena, Oregon. Groundwater levels in the Wanapum basalt unit do not show long-term declines in the upper Umatilla River Basin. Because of pumping, some areas in the upper Umatilla River Basin have shown a decrease, or reversal, in the upward vertical head gradient.Key data needs are improvement of the spatial and temporal distribution of water-level data collection and continued monitoring of streamflow gaging sites. Additionally, refinement of recharge estimates would enhance understanding of the processes that provide the groundwater resources in the upper Umatilla River Basin.

Surface sediment remobilization triggered by earthquakes in the Nankai forearc region

NASA Astrophysics Data System (ADS)

Okutsu, N.; Ashi, J.; Yamaguchi, A.; Irino, T.; Ikehara, K.; Kanamatsu, T.; Suganuma, Y.; Murayama, M.

2017-12-01

Submarine landslides triggered by earthquakes generate turbidity currents (e.g. Piper et al., 1988; 1999). Recently several studies report that the remobilization of the surface sediment triggered by earthquakes can also generate turbidity currents. However, studies that proposed such process are still limited (e.g. Ikehara et al., 2016; Mchugh et al., 2016; Moernaut et al., 2017). The purpose of this study is to examine those sedimentary processes in the Nankai forearc region, SW Japan using sedimentary records. We collected 46 cm-long multiple core (MC01) and a 6.7 m-long piston core (PC03) from the small basin during the R/V Shinsei Maru KS-14-8 cruise. The small confined basin, which is our study site, block the paths of direct sediment supply from river-submarine canyon system. The sampling site is located at the ENE-WSW elongated basin between the accretionary prism and the forearc basin off Kumano without direct sediment supply from river-submarine canyon system. The basin exhibits a confined basin that captures almost of sediments supplied from outside. Core samples are mainly composed of silty clay or very fine sand. Cs-137 measurement conducted on a MC01 core shows constantly high value at the upper 17 cm section and no detection below it. Moreover, the sedimentary structure is similar to fine-grained turbidite described by Stow and Shanmgam (1980), we interpret the upper 17 cm of MC01 as muddy turbidite. Grain size distribution and magnetic susceptibility also agree to this interpretation. Rapid sediment deposition after 1950 is assumed and the most likely event is the 2004 off Kii peninsula earthquakes (Mw=6.6-7.4). By calculation from extent of provenance area, which are estimated by paleocurrent analysis and bathymetric map, and thickness of turbidite layer we conclude that surface 1 cm of slope sediments may be remobilized by the 2004 earthquakes. Muddy turbidites are also identified in a PC03 core. The radiocarbon age gap of 170 years obtained around 2 mbsf of PC03 core also indicates similar sedimentary process. However, we also obtained large age gap in a thick turbidite layer, indicating remobilization of deeper sediments by landslide. Our results revealed that the studied basin recorded various scales and styles of sediment remobilizations by earthquake shakings.

Evolving Concepts and Teaching Approaches In Tectonics and Sedimentation.

ERIC Educational Resources Information Center

Graham, Stephan Alan

1983-01-01

Discusses five recent advances in sedimentary tectonics, noting how they are incorporated into college curricula. Advances discussed include basin type, tectonic setting, facies analysis (in conjunction with basin type/setting), stratigraphic analysis of reflection seismic data, and quantitative analysis of subsidence histories of sedimentary…

Multilayered aquifer modeling in the coastal sedimentary basin of Togo

NASA Astrophysics Data System (ADS)

Gnazou, M. D. T.; Sabi, B. E.; Lavalade, J. L.; Schwartz, J.; Akakpo, W.; Tozo, A.

2017-01-01

This work is a follow up to the hydrogeological synthesis done in 2012 on the coastal sedimentary basin of Togo. That synthesis notably emphasized the lack of piezometric monitoring in the last thirty years. This has kept us from learning about the dynamics and evolution of the resource in the context of rapidly increasing demand. We are therefore presenting a model for understanding flows, and its main objectives are to provide an initial management tool that should evolve with time as new data (piezometric monitoring, pumping tests, etc.) become available, and to determine what new information can be obtained that will help policy makers to manage the resource better. The results of steady state flow calibration have shown that the aquifer of the Continental Terminal overexploited in the West, can still be exploited in the East of the basin, the Maastrichtian on the whole basin. On the other hand, exploitation of Paleocene aquifers should be done with care.

Simulations of Ground Motion in Southern California based upon the Spectral-Element Method

NASA Astrophysics Data System (ADS)

Tromp, J.; Komatitsch, D.; Liu, Q.

2003-12-01

We use the spectral-element method to simulate ground motion generated by recent well-recorded small earthquakes in Southern California. Simulations are performed using a new sedimentary basin model that is constrained by hundreds of petroleum industry well logs and more than twenty thousand kilometers of seismic reflection profiles. The numerical simulations account for 3D variations of seismic wave speeds and density, topography and bathymetry, and attenuation. Simulations for several small recent events demonstrate that the combination of a detailed sedimentary basin model and an accurate numerical technique facilitates the simulation of ground motion at periods of 2 seconds and longer inside the Los Angeles basin and 6 seconds and longer elsewhere. Peak ground displacement, velocity and acceleration maps illustrate that significant amplification occurs in the basin. Centroid-Moment Tensor mechanisms are obtained based upon Pnl and surface waveforms and numerically calculated 3D Frechet derivatives. We use a combination of waveform and waveform-envelope misfit criteria, and facilitate pure double-couple or zero-trace moment-tensor inversions.

Diversity and distribution of fungal communities in the marine sediments of Kongsfjorden, Svalbard (High Arctic)

NASA Astrophysics Data System (ADS)

Zhang, Tao; Fei Wang, Neng; Qin Zhang, Yu; Yu Liu, Hong; Yan Yu, Li

2015-10-01

This study assessed the diversity and distribution of fungal communities in eight marine sediments of Kongsfjorden (Svalbard, High Arctic) using 454 pyrosequencing with fungal-specific primers targeting the internal transcribed spacer (ITS) region of the ribosomal rRNA gene. Sedimentary fungal communities showed high diversity with 42,219 reads belonging to 113 operational taxonomic units (OTUs). Of these OTUs, 62 belonged to the Ascomycota, 26 to Basidiomycota, 2 to Chytridiomycota, 1 to Zygomycota, 1 to Glomeromycota, and 21 to unknown fungi. The major known orders included Hypocreales and Saccharomycetales. The common fungal genera were Pichia, Fusarium, Alternaria, and Malassezia. Interestingly, most fungi occurring in these Arctic sediments may originate from the terrestrial habitats and different basins in Kongsfjorden (i.e., inner basin, central basin, and outer basin) harbor different sedimentary fungal communities. These results suggest the existence of diverse fungal communities in the Arctic marine sediments, which may serve as a useful community model for further ecological and evolutionary study of fungi in the Arctic.

Cordilleran hingeline: Late Precambrian rifted margin of the North American craton and its impact on the depositional and structural history, Utah and Nevada

NASA Astrophysics Data System (ADS)

Picha, Frank; Gibson, Richard I.

1985-07-01

The structural pattern set by late Precambrian rifting and fragmentation of the North American continent is apparent in both sedimentary and tectonic trends in western Utah and eastern Nevada. The late Precambrian cratonic margin (Cordilleran hingeline) displays several prominent structural features, such as the Wasatch and Ancient Ephraim faults, Fillmore arch and northeast-trending lineaments, which were repeatedly reactivated as structural uplifts, ramps, strike-slip faults, and extensional detachments. The renewed activity affected, among others, the geometry of the late Paleozoic Ancestral Rocky Mountain uplifts and basins, the extent of the Jurassic Arapien basin, the sedimentary pattern of the Cretaceous foreland basin, the geometry of the Sevier orogenic belt, and the extent and type of Basin-and-Range extensional tectonics. The rifted cratonic margin has thus remained a major influence on regional structures long after rifting has ceased. *Present address: Everest Geotech, 10101 Southwest Freeway, Houston, Texas 77074

High resolution seismic stratigraphy and sedimentological signature of the Late Quaternary deposits in the northern Western Basin (Ross Sea, Antarctica)

NASA Astrophysics Data System (ADS)

Corradi, N.; Finocchiaro, F.; Ivaldi, R.; Melis, R.; Pittà, A.

2003-04-01

The northern Western Basin is a sector of the continental shelf of the Western Ross Sea that is considered to be the natural northward extension of the Drygalski Basin by many authors. The literature provides a general model of the evolution of the basin and the recent papers propose a seismic stratigraphy for the post-Miocene sedimentation. However, the sedimentary processes during the Late Quaternary and, in particular, the Last Glacial Maximum (LGM) are still little understood (Brambati et al., 2001). In this paper we present the preliminary results of the very high-resolution seismic surveys (Sub Bottom Profiler, Huntec Deep Tow Boomer and Sparker) and their calibration with the sediment samples collected during the three Marine Geology Campaigns of the PNRA (XIII, XIV and XVII), with the scientific objective of the research to investigate the role of the East Antarctic Ice Sheet (EAIS) in the morphogenesis and deposition of the Late Quaternary sedimentary series.

Giant rhinoceros Paraceratherium and other vertebrates from Oligocene and middle Miocene deposits of the Kağızman-Tuzluca Basin, Eastern Turkey.

PubMed

Sen, Sevket; Antoine, Pierre-Olivier; Varol, Baki; Ayyildiz, Turhan; Sözeri, Koray

2011-05-01

A recent fieldwork in the Kağızman-Tuzluca Basin in northeastern Turkey led us to the discovery of three vertebrate localities which yielded some limb bones of the giant rhino Paraceratherium, a crocodile tooth, and some small mammals, respectively. These discoveries allowed, for the first time to date some parts of the sedimentary units of this basin. This study also shows that the dispersal area of Paraceratherium is wider than it was known before. Eastern Turkey has several Cenozoic sedimentary basins formed during the collision of the Arabian and Eurasian plates. They are poorly documented for vertebrate paleontology. Consequently, the timing of tectonic activities, which led to the formation of the East Anatolian accretionary complex, is not constrained enough with a solid chronological framework. This study provides the first biostratigraphic evidences for the infill under the control of the compressive tectonic regime, which built the East Anatolian Plateau.

The Middle Miocene of the Fore-Carpathian Basin (Poland, Ukraine and Moldova)

NASA Astrophysics Data System (ADS)

Wysocka, Anna; Radwański, Andrzej; Górka, Marcin; Bąbel, Maciej; Radwańska, Urszula; Złotnik, Michał

2016-09-01

Studies of Miocene sediments in the Fore-Carpathian Basin, conducted by geologists from the University of Warsaw have provided new insights on the distribution of the facies infilling the basin, particularly in the forebulge and back-bulge zones. The origin of the large-scale sand bodies, evaporitic deposits and large-scale organic buildups is discussed, described and verified. These deposits originated in variable, shallow marine settings, differing in their water chemistry and the dynamics of sedimentary processes, and are unique with regard to the fossil assemblages they yield. Many years of taxonomic, biostratigraphic, palaeoecologic and ecotaphonomic investigations have resulted in the identification of the fossil assemblages of these sediments, their age, sedimentary settings and post-mortem conditions. Detailed studies were focused on corals, polychaetes, most classes of molluscs, crustaceans, echinoderms, and fishes.

Extreme events in the sedimentary record of maar Lake Pavin: Implications for natural hazards assessment in the French Massif Central

NASA Astrophysics Data System (ADS)

Chassiot, Léo; Chapron, Emmanuel; Di Giovanni, Christian; Albéric, Patrick; Lajeunesse, Patrick; Lehours, Anne-Catherine; Meybeck, Michel

2016-06-01

A set of sedimentary cores, high resolution swath bathymetry and subbottom profiler data provides new insights on sedimentary processes in meromictic maar Lake Pavin, France. Three sedimentary environments (i.e., littoral, plateau and basin) have been identified in the lake from sediment composition using bulk organic geochemistry and the analysis of hydroacoustic images. Various forms of rapidly deposited layers (RDLs) have been identified and radiocarbon dated. An up to date stratigraphy of sedimentary events matching coeval RDLs across the lake is presented and illustrates a wide range of natural hazards linked to Lake Pavin during the last 2000 years. In AD 600, a sudden lake outburst triggered a slump deposit along with a 9 m lake-level drop that drove shifts in sedimentary organic matter composition. Outside the lake, outburst flood deposits have been described downstream and provide sedimentary evidence for this event. The lake-level drop also favored the generation of gravity reworking processes, as shown by (1) a regional earthquake-triggered large slope failure on the plateau connected to a mass-wasting deposit in the basin dated to AD 1300, and (2) a succession of turbidites in AD 1825 and AD 1860 contemporaneous to two historic earthquakes, suggesting that this lake is sensitive to earthquakes with a minimum epicentral intensity of V. Finally, past observations of lake water color changes in AD 1783 and AD 1936, similar to reports in other meromictic lakes, match iron-rich deposits identified in maar lake sediments and suggest that Lake Pavin could have undergone limnic eruptions.

Preface

NASA Astrophysics Data System (ADS)

Mohriak, Webster; Talwani, Manik

In compiling this volume, we have aimed to develop and enhance our current understanding of the structural evolution and sedimentation processes along divergent continental margins. To counteract the unfortunate situation of a lack of modem seismic and potential fields data on circum-Atlantic passive margins in the literature, we have linked new data from oil companies with that of research institutions. To update the data offered in most volumes used as reference works for the study of continental margins, now upwards of 20 years old, and to remedy the dispersal of important, more recent contributions in specialized journals, we present a current synthesis of materials in one volume focused on the deeper geology of the sedimentary basins along continental margins. In the early 1990s, as oil companies and other institutions developed tools to probe deeper into the architecture of passive margin sedimentary basins, a great amount of data based on regional deep seismic profiles evolved rapidly from its specialized niche as geophysical interpretation of the Earth's interior to widespread use by those same companies and institutions. At the same time, these findings demonstrated that some breakthroughs in data acquisition, processing and interpretation initially achieved by research institutions could almost instantaneously be globalized throughout different research groups, thereby influencing the thinking of geoscientists worldwide.

Oil exploration and development in Marib/Al Jawf basin, Yemen Arab Republic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maycock, I.D.

1986-07-01

In 1981, Yemen Hunt Oil Company (YHOC) negotiated a production-sharing agreement covering 12,600 km/sup 2/ in the northeast part of the Yemen Arab Republic. A reconnaissance seismic program of 1864 km acquired in 1982 revealed the presence of a major half graben, designated the Marib/Al Jawf basin by YHOC. A sedimentary section up to 18,000 ft thick has been recognized. Geologic field mapping identified Jurassic carbonates covered by Cretaceous sands overlying Permian glaciolacustrine sediments, Paleozoic sandstones, or Precambrian basement. The first well drilled in 1984, aimed at a possible Jurassic carbonate objective, encountered hydrocarbon-bearing sands in the Jurassic-Cretaceous transition betweenmore » 5000 and 6000 ft. A successful appraisal drilling program has demonstrated satisfactory lateral reservoir continuity. Further wildcat drilling demonstrates macro-unit correlation within the eastern part of the basin. Rapid basin development apparently commenced in the late Kimmeridgian, culminating with the deposition of Tithonian evaporites. Available geochemical analysis indicates sourcing from restricted-basin sediments. Excellent traps, reservoirs, and source beds underlying the Tithonian evaporites indicate that a significant new petroliferous province is present.« less

Classification and sedimentary characteristics of lacustrine hyperpycnal channels: Triassic outcrops in the south Ordos Basin, central China

NASA Astrophysics Data System (ADS)

Xian, Benzhong; Wang, Junhui; Gong, Chenglin; Yin, Yu; Chao, Chuzhi; Liu, Jianping; Zhang, Guodong; Yan, Qi

2018-06-01

Subaquatic channels are known as active conduits for the delivery of terrigenous sediments into related marine and lacustrine basins, as well as important targets for hydrocarbon exploration. Compared to submarine channels, lacustrine subaqueous channels created by hyperpycnal flows are understudied. Using well-exposed outcrops collected from three different locations in the southern Ordos Basin, central China, morphologies and architecture of a channelized hyperpycnal system were studied and classified. Six facies associations represent sedimentary processes from strong erosion by bedload dominated hyperpycnal flows, to transitional deposition jointly controlled by bedload and suspended-load dominated hyperpycnal flows, finally to deposition from suspended-load dominated hyperpycnal flows. On the basis of channel morphologies, infilling sediments and sedimentary processes, the documented channels can be classified into four main categories, which are erosional, bedload dominated, suspended-load dominated, and depositional channels. In very proximal and very distal locations, erosional channels and depositional channels serve as two end-members, while in middle areas, bedload-dominated channels and suspended-load dominated channels are transitional types. Erosional channels, as a response to strong erosion from bedload dominated hyperpycnal flows on upper slope, were mainly filled by mud interbedded with thin sand beds. As flow energy decreases, bedload dominated channels develop on middle slopes, which are characterized mainly by under- to balanced sediment infillings with cross-bedded sandstones and/or minor massive sandstones. Compared to bedload dominated channels, suspended-load dominated channels mainly develop in deeper water, and were filled mainly by massive or planar-laminated sandstones. Depositional channels, as a response to suspended-load dominated hyperpycnal flows in deep-water areas, are characterized by thin-medium bed classical turbidites with Bouma sequences and thin- to thick massive sandstones. Such evolution patterns of hyperpycnal channel systems are ascribed to the progressive decrease in flow capacity of hyperpycnal flows, and provide an adequate explanation for the basinward channelization behavior of hyperpycnal systems.

Geodynamic evolution and sedimentary infill of the northern Levant Basin: A source to sink-perspective

NASA Astrophysics Data System (ADS)

Hawie, N.

2013-12-01

Nicolas Hawie a,b,c (nicolas.hawie@upmc.fr) Didier Granjeon c (didier.granjeon@ifpen.fr) Christian Gorini a,b (christian.gorini@upmc.fr) Remy Deschamps c (remy.deschamps@ifpen.fr) Fadi H. Nader c (fadi-henri.nader@ifpen.fr) Carla Müller Delphine Desmares f (delphine.desmares@upmc.fr) Lucien Montadert e (lucien.montadert@beicip.com) François Baudin a (francois.baudin@upmc.fr) a UMR 7193 Institut des Sciences de la Terre de Paris, Université Pierre et Marie Curie/ Univ. Paris 06, case 117. 4, place Jussieu 75252 Paris Cedex 05, France b iSTEP, UMR 7193, CNRS, F-75005, Paris, France c IFP Energies nouvelles, 1-4 avenue du Bois Préau 92852 Rueil Malmaison Cedex, France d UMR 7207, Centre de Recherche sur la Paleobiodiversité et les Paleoenvironnements. Université Pierre et Marie Curie, Tour 46-56 5ème. 4, place Jussieu 75252 Paris Cedex 05, France e Beicip Franlab, 232 Av. Napoléon Bonaparte, 95502 Rueil-Malmaison, France Sedimentological and biostratigraphic investigations onshore Lebanon coupled with 2D offshore reflection seismic data allowed proposing a new Mesozoic-Present tectono-stratigraphic framework for the northern Levant Margin and Basin. The seismic interpretation supported by in-depth facies analysis permitted to depict the potential depositional environments offshore Lebanon as no well has yet been drilled. The Levant region has been affected by successive geodynamic events that modified the architecture of its margin and basin from a Late Triassic to Middle Jurassic rift into a Late Cretaceous subduction followed by collision and Miocene-Present strike slip motion. The interplay between major geodynamic events as well as sea level fluctuations impacted on the sedimentary infill of the basin. During Jurassic and Cretaceous, the Levant Margin is dominated by the aggradation of a carbonate platform while deepwater mixed-systems prevailed in the basin. During the Oligo-Miocene, three major sedimentary pathways are expected to drive important quantities of clastic material into the Levant Basin: (1) the marginal canyons along the Levant Margin, (2) the Latakia region and the Palmyrides Basin (Syria) and (3) the Red Sea area and Nile Delta. Regional drainage system analysis was performed to estimate the contribution to the infill of the basin of the different sediment sources, and in particular, to estimate erosion of Nubian siliciclastic material, granitic Red Sea rift shoulders and Arabian Shield. A numerical stratigraphic forward model, Dionisos, was used to test these source-to-sink assumptions; a sensitivity analysis was then performed to understand better the impact of the different geodynamic and stratigraphic scenarios on the architecture and sedimentary infill of the Levant Basin, and thus on the expected petroleum systems of this frontier basin

The evolution of the Danube gateway between Central and Eastern Paratethys (SE Europe): Insight from numerical modelling of the causes and effects of connectivity between basins and its expression in the sedimentary record

NASA Astrophysics Data System (ADS)

Leever, K. A.; Matenco, L.; Garcia-Castellanos, D.; Cloetingh, S. A. P. L.

2011-04-01

The Pannonian and Dacic Basins in SE Europe are presently connected by the Danube River across the South Carpathians, to which they are in a back-arc and foreland position respectively. Part of the Paratethys realm during the Neogene, open water communication between the basins was interrupted by the Late Miocene uplift of the Carpathians. Different mechanisms have been proposed for the formation of the Danube gateway: capture of the upstream lake or an upstream river or incision of an antecedent river. Estimates on its age range from Late Miocene to Quaternary. A related issue is the effect of the large Mediterranean sea level fall related to the Messinian Salinity Crisis on the Paratethys subbasins, specifically the "isolated" Pannonian Basin. In a synthetic numerical modelling study, using a pseudo-3D code integrating tectonics, surface processes and isostasy, we addressed the causes and effects of changes in connectivity between two large sedimentary basins separated by an elevated barrier. Specifically, we aimed to find the expression of connectivity events in the sedimentary record in general and the consequences for the evolution of the Pannonian-Dacic area in particular. We studied a range of parameters including the geometry and uplift rate of the barrier, downstream sea level change and lithosphere rigidity. We found that changes in connectivity are expressed in the sedimentary record through their effect on base level in the upstream basin and supply in the downstream basin. The most important factors controlling the response are the elevation difference between the basins and the upstream accommodation space at the time of reconnection. The most pronounced effect of reconnection through lake capture is predicted for a large elevation difference and limited upstream accommodation space. Downstream increase in sediment supply is dependent on the latter rather than the reconnection event itself. Of the parameters we tested, the rigidity of the lithosphere was found to be of major importance by its control on sediment loaded subsidence and generation of accommodation space. A downstream sea level change is unlikely to induce capture, but may affect the upstream lake level by enhancing incision in a pre-existing gateway. In the Pannonian-Dacic region, the mechanically weak, continuously subsiding Pannonian lithosphere allowed accommodation of significant volumes of continental sedimentation and as a consequence, transfer of excess sediment to the downstream Dacic Basin was only gradual. The Messinian sea level fall in the Dacic Basin could have been recorded in the Pannonian Basin only if a connection between the basins already existed. More detailed modelling of river incision taking into account lateral differences in erodibility in the South Carpathians will be required to give better time constraints on the formation of the Danube Gateway.

Sedimentary Basin Structure of the Hadar Formation's Lacustrine-Dominated Depocenter (Ledi-Geraru, Afar, Ethiopia) and its Relevance for Investigating Hominin Paleoenvironments

NASA Astrophysics Data System (ADS)

Dimaggio, E. N.; Campisano, C. J.; Arrowsmith, J. R.; Dupont-Nivet, G.; Johnson, R. A.; Warren, M. B.

2008-12-01

Sedimentary sequences preserved in East African rift basins record the long-term response of past depositional environments to climatic and tectonic forcing. Motivations for recent field investigations at the Ledi-Geraru site, part of the greater Hadar sedimentary basin in the Afar region of Ethiopia, stem from a need to characterize local basin structure and expand and refine interpretations of the complex mid-late Pliocene history of local and regional-scale landscape change during a time of critical importance for understanding hominin evolution. Detailed geologic mapping (1:7,000), measured stratigraphic sections, and seismic reflection surveys provide the datasets necessary for basin evaluation. The Ledi-Geraru sedimentary sequence (>250m thick) exposes nearly the entirety of the hominin-bearing Hadar Formation of west- central Afar. Both primary unmodified lake deposits and intervals modified by subsequent subaerial exposure and pedogenesis are well-exposed. The lacustrine-dominated signature is indicated by the prevalence of laminated silty clays that contain leaf impressions, fish scales, and gastropod shells, undisturbed laminated diatomite and clays, and pedogenically modified diatomaceous silts. The sequence is generally flat lying, with low bedding dips ranging from 0-2° NNW to <1° NNE and minor NNW trending faults with <5 m vertical offset. Whereas coeval fluvio-lacustrine sediments associated with hominin and archaeological sites west of Ledi-Geraru (e.g., Hadar and Gona) are marked by comparatively slow and episodic sedimentation, sedimentation rates in the Ledi-Geraru sequence are extremely high and consistent, on the order of ~0.9-1.0mm/yr. Laterally extensive tephra marker beds and paleomagnetic records provide excellent age control for sedimentation rate estimates and correlation to nearby fossil-rich sequences. As the Hadar basin sediments preserve a rich paleoanthropologic and archaeological record, this work provides the geologic framework necessary for a proposed (2011) continental drilling effort to obtain a near-continuous, ultra-high resolution terrestrial record of past climate variability from multiple paleo-lake basins in East Africa, including the Ledi-Geraru. A seismic reflection survey was completed there in spring 2008, below the planned drilling site. Gently east-dipping coherent reflections interpreted to be from the Ledi-Geraru sedimentary sequence are imaged in the seismic data to at least 0.2 to 0.3 s (two-way travel time). Preliminary average velocities of about 2000 m/s suggest a sequence thickness of 200-300 m. Furthermore, there is no indication of large-offset faults or of buried basalt ridges that would disrupt or reduce the stratigraphic column available for coring. The anticipated cores from Ledi-Geraru should yield a high-resolution chronostratigraphic framework and paleoenvironmental record from >3.5 to 2.9Ma. Combined geologic and seismic evaluations of depositional sequences are central for evaluating the geometry, tectonic evolution, and stratigraphic history of basins and facilitate interpretations of the space-time progression of evolving paleosurfaces.

Tectono-sedimentary analysis using the anisotropy of magnetic susceptibility: a study of the terrestrial and freshwater Neogene of the Orava Basin

NASA Astrophysics Data System (ADS)

Łoziński, Maciej; Ziółkowski, Piotr; Wysocka, Anna

2017-10-01

The Orava Basin is an intramontane depression filled with presumably fine-grained sediments deposited in river, floodplain, swamp and lake settings. The basin infilling constitutes a crucial record of the neoalpine evolution of the Inner/Outer Carpathian boundary area since the Neogene, when the Jurassic-Paleogene basement became consolidated, uplifted and eroded. The combination of sedimentological and structural studies with anisotropy of magnetic susceptibility (AMS) measurements provided an effective tool for recognition of terrestrial environments and deformations of the basin infilling. The lithofacies-oriented sampling and statistical approach to the large dataset of AMS specimens were utilized to define 12 AMS facies based on anisotropy degree (P) and shape (T). The AMS facies allowed a distinction of sedimentary facies ambiguous for classical methods, especially floodplain and lacustrine sediments, as well as revealing their various vulnerabilities to tectonic modification of AMS. A spatial analysis of facies showed that tuffites along with lacustrine and swamp deposits were generally restricted to marginal and southern parts of the basin. Significant deformations were noticed at basin margins and within two intrabasinal tectonic zones, which indicated the tectonic activity of the Pieniny Klippen Belt after the Middle Miocene. The large southern area of the basin recorded consistent N-NE trending compression during basin inversion. This regional tectonic rearrangement resulted in a partial removal of the southernmost basin deposits and shaped the basin's present-day extent.

The Upstream and Downstream impact of Milankovitch cycles in continental nonmarine sedimentary records

NASA Astrophysics Data System (ADS)

Valero, Luis; Garcés, Miguel; Huerta, Pedro; Cabrera, Lluís

2016-04-01

Discerning the effects of climate in the stratigraphic record is crucial for the comprehension of past climate changes. The signature of climate in sedimentary sequences is often assessed by the identification of Milankovitch cycles, as they can be recognized due to their (quasi) periodic behaviour. The integration of diverse stratigraphic disciplines is required in order to understand the different processes involved in the expression of the orbital cycles in the sedimentary records. New advances in Stratigraphy disclose the different variables that affect the sedimentation along the sediment routing systems. These variables can be summarized as the relationship between accommodation and sediment supply (AS/SS), because they account for the shifts of the total mass balance of a basin. Based in these indicators we propose a synthetic model for the understanding of the expression of climate in continental basins. Sedimentation in internally drained lake basins is particularly sensitive to net precipitation/evaporation variations. Rapid base level oscillations modify the AS/SS ratio sufficiently as to mask possible sediment flux variations associated to the changing discharge. On the other hand, basins lacking a central lacustrine system do not experience climatically-driven accommodation changes, and thus are more sensitive to archive sediment pulses. Small basins lacking carbonate facies are the ideal candidates to archive the impact of orbital forcing in the landscapes, as their small-scale sediment transfer systems are unable to buffer the upstream signal. Sedimentation models that include the relationship between accommodation and sediment supply, the effects of density and type of vegetation, and its coupled response with climate are needed to enhance their reliability.

Why is there a large submarine landslide in the Jan Mayen Ridge, north Norway?

NASA Astrophysics Data System (ADS)

Kawamura, Kiichiro; Sverre Laberg, Jan

2013-04-01

This paper deals with the formation process/mechanism of a large submarine landslide in the Jan Mayen Ridge. The Jan Mayen Ridge, being a continental sliver, is ~250 km long in N-S direction with a flat plateau of ~800 m in water depth standing on an abyssal plane of 2500-3000 m in water depth. There is only a large submarine landslide scar of ~50 km wide in the central east side. In the central east side, the internal geologic architecture is characterized by an Eocene-Oligocene sedimentary sequence, which tilts eastward. This sedimentary sequence is cut by large normal faults, that have formed by the spread of the Norwegina-Greenland Sea since 20 Ma. The wasted mass of the large submarine landslide could slip down along the bedding plane and/or the normal faults dipping to east. Thus, the slide form a big spoon-shaped basin. The slide scar was collapsed retrogressively to make a small spoon-shaped basin on the upper part of the big basin. There are long channels from the retrogressive slide scars to the lower basin. The retrogressive slides would continue to discharge progressively gravity flows to make the long channels on the basin after the large submarine landslide occurred. On contrary to the slide region, the sedimentary sequence has a large anticline in an east foot of the ridge in other regions. This anticline could be an obstruction to a large submarine landslide. Thus, the geologic architecture plays an important role in the formation mechanism of a large submarine landslides in the Jan Mayen Ridge.

Determining Crustal Structure beneath the New Madrid Seismic Zone and Adjacent Areas: Application of a Reverberation-removal Filter

NASA Astrophysics Data System (ADS)

Liu, L.; Gao, S. S.; Liu, K. H.

2015-12-01

The New Madrid Seismic Zone (NMSZ) and some of the adjacent areas are covered by a low-velocity sedimentary sequence, giving rise to strong reverberations in the P-to-S receiver functions (RFs) and making it difficult to reliably determine crustal thickness and Poisson's ratio using the conventional H-k stacking technique. Here we apply a newly developed technique (Yu et al., 2015; doi: 10.1002/2014JB011610) to effectively remove or reduce the reverberations from the sedimentary layer to obtain more reliable results. Stacking of a total of 38528 radial RFs recorded by 343 stations in the study area shows systematic spatial variations in crustal thickness (H), Vp/Vs ratio and amplitude (R; relative to the direction P) of the converted Moho phases. Our results indicate that the upper Mississippi Embayment (ME), a broad southwest-plunging trough with the thickest sedimentary layer in the study area, is characterized by a thin crustal thickness (~32 km), while adjacent areas have relatively thicker crust (>40 km). This area also possesses relatively large Vp/Vs (>1.85) values, suggesting possible intrusion of mantle-derived mafic rocks. Most part of the Ozark Uplift is characterized by relatively small Vp/Vs (<1.79) values which indicate an overall felsic crust. In contrast to the NMSZ which is part of the Reelfoot rift, the southern Illinois Basin, which is an intracontinental sag basin, is characterized by a crust of about 45 km which is a few km thicker than the surrounding areas, and a normal Vp/Vs, suggesting sharp differences in crustal structure between rift and sag basins.

Vertical plate motions from ancient buried landscapes: Constraints on Icelandic plume evolution

NASA Astrophysics Data System (ADS)

Stucky de Quay, G.

2016-12-01

Convection in the Earth's mantle is strongly time-dependent (Ra 106-108). In regions that are dynamically supported, uplift and subsidence histories might therefore contain information about evolution of mantle convection. We examine uplift and subsidence histories of sedimentary basins fringing NW Europe, close to the Icelandic plume, where it has been shown short-term vertical motions disrupt post-rift thermal subsidence. These sedimentary basins contain ancient (59-53 Ma) buried fluvial landscapes which developed during inception of the Icelandic plume. Stratigraphic and seismic reflection data indicate that these terrestrial landscapes were incised by 100s of meters in only a few million years and were then rapidly submerged. We extracted a landscape buried beneath 1.5 km of sedimentary rock in the Bressay region, offshore eastern Scotland. This landscape was mapped using a three-dimensional 9000 km2 seismic dataset and seven exploration wells. First, the buried landscape was mapped using every inline and cross line (horizontal resolution 12 m). Second, the landscape was depth converted and decompacted using check-shot data. Third, drainage patterns were reconstructed by calculating flow directions across the mapped landscape. River profiles were extracted from these drainage patterns and contain three knickzones analogous to those documented in an older buried landscape in the Faereo-Shetland Basin, 400 km to the west. Fourth, we reinterpreted dinocyst records to determine the age of our landscape, allowing us to constrain erosion rates. Finally, our drainage inventory was inverted for uplift rate as a function of space and time. Results indicate three uplift events occurred between 55-57 Ma, resulting in a total cumulative uplift of 400 m. We combine these results with estimates of uplift in nearby regions to constrain the behavior of the incipient Icelandic plume both in a temporal and spatial context.

A new age model for the early-middle Miocene in the North Alpine Foreland Basin

NASA Astrophysics Data System (ADS)

Reichenbacher, Bettina; Krijgsman, Wout; Pippèrr, Martina; Sant, Karin; Kirscher, Uwe

2016-04-01

The establishment of high-resolution age models for sedimentary successions is crucial for numerous research questions in the geosciences and related disciplines. Such models provide an absolute chronology that permits precise dating of depositional episodes and related processes such as mountain uplift or climate change. Recently, our work in the Miocene sediments of the North Alpine Foreland Basin (NAFB) has revealed a significantly younger age (16.6 Myr) for sediments that were thought to have been deposited 18 Myr ago. This implies that a fundamentally revised new age model is needed for the entire suite of lower-middle Miocene sedimentary rocks in the NAFB (20 to 15-Myr). Our new data also indicate that previously published reconstructions of early-middle Miocene palaeogeography, sedimentation dynamics, mountain uplift and climate change in the NAFB all require a critical review and revision. Further, the time-span addressed is of special interest, since it encompasses the onset of a global warming phase. However, it appears that a fundamentally revised new age model for the entire suite of lower-middle Miocene sedimentary rocks in the NAFB can only be achieved based on a 500 m deep drilling in the NAFB for which we currently seek collaboration partners to develop a grant application to the International Continental Deep Drilling Program (ICDP). Reference: Reichenbacher, B., W. Krijgsman, Y. Lataster, M. Pippèrr, C. G. C. Van Baak, L. Chang, D. Kälin, J. Jost, G. Doppler, D. Jung, J. Prieto, H. Abdul Aziz, M. Böhme, J. Garnish, U. Kirscher, and V. Bachtadse. 2013. A new magnetostratigraphic framework for the Lower Miocene (Burdigalian/Ottnangian, Karpatian) in the North Alpine Foreland Basin. Swiss Journal of Geosciences 106:309-334.

PUMa - modelling the groundwater flow in Baltic Sedimentary Basin

NASA Astrophysics Data System (ADS)

Kalvane, G.; Marnica, A.; Bethers, U.

2012-04-01

In 2009-2012 at University of Latvia and Latvia University of Agriculture project "Establishment of interdisciplinary scientist group and modelling system for groundwater research" is implemented financed by the European Social Fund. The aim of the project is to develop groundwater research in Latvia by establishing interdisciplinary research group and modelling system covering groundwater flow in the Baltic Sedimentary Basin. Researchers from fields like geology, chemistry, mathematical modelling, physics and environmental engineering are involved in the project. The modelling system is used as a platform for addressing scientific problems such as: (1) large-scale groundwater flow in Baltic Sedimentary Basin and impact of human activities on it; (2) the evolution of groundwater flow since the last glaciation and subglacial groundwater recharge; (3) the effects of climate changes on shallow groundwater and interaction of hydrographical network and groundwater; (4) new programming approaches for groundwater modelling. Within the frame of the project most accessible geological information such as description of geological wells, geological maps and results of seismic profiling in Latvia as well as Estonia and Lithuania are collected and integrated into modelling system. For example data form more then 40 thousands wells are directly used to automatically generate the geological structure of the model. Additionally a groundwater sampling campaign is undertaken. Contents of CFC, stabile isotopes of O and H and radiocarbon are the most significant parameters of groundwater that are established in unprecedented scale for Latvia. The most important modelling results will be published in web as a data set. Project number: 2009/0212/1DP/1.1.1.2.0/09/APIA/VIAA/060. Project web-site: www.puma.lu.lv

Petroleum system of Northwest Java basin based on gravity data analysis

NASA Astrophysics Data System (ADS)

Widianto, E.

2018-01-01

Energy management in the upstream oil and gas sector becomes very important for the country’s energy security. The renewal of energy resources and reserves becomes necessary and is a must. In the oil and gas industry, gravity data is usually used only for regional surveys, but with the development of instrumentation technology and gravity software development, this method can be used for assessing oil and gas survey stages from exploration to production. This study was conducted to evaluate aspects of petroleum system and exploration play concept in the part of Northwest Java Basin, covering source rock deposition regions (source kitchen area, migration direction), development of reservoirs, structural and stratigraphic trap, based on gravity data. This study uses data from Bouguer gravity anomaly map by filtering process to produce a residual map depicting sedimentation basin configuration. The mapping generated 20 sedimentary basins in Java Island with the total hydrocarbon resources of 113 BBOE (Billion Barrel of Oil Equivalent). The petroleum system analysis was conducted in the Northwest Basin section. The final map produced illustrates the condition of petroleum system and play concept that can be used as exploration direction, expectedly reducing the risk of drilling failure.

Petrography and chemistry of the bed sediments of the Red River in China and Vietnam: Provenance and chemical weathering

NASA Astrophysics Data System (ADS)

Borges, Joniell; Huh, Youngsook

2007-02-01

The Red (Hong) River straddles southwestern China and northern Vietnam and drains the eastern Indo-Asian collision zone. We collected bed sediments from its tributaries and main channel and report the petrographic point counts of framework grains and major oxide compositions as well as organic and inorganic carbon contents. The Q:F:Rf ratios and Q:F:(L-L c) ratios of the bed-load indicate quartz-poor, mineralogically immature sediments of recycled orogen provenance. The weathering indices based on major oxides — the chemical index of alteration (CIA) and the weathering index of Parker — are also consistent with the recycled sedimentary nature of the bed sediments. Using geographic information system (GIS) we calculated for each sample basin such parameters as temperature, precipitation, potential evapotranspiration, runoff, basin length, area, relief, and areal exposure of igneous, metamorphic and sedimentary rocks. Statistically meaningful correlations are obtained between the two weathering indices, between CIA and sedimentary to metamorphic rock fragments ratio, S / (S + M), and between CIA and sedimentary rock cover, but otherwise correlations are poor. The bed sediments preserve signatures of their provenance, but the effect of weathering is not clearly seen. Subtle differences in the bed sediments are observed between the Red and the Himalayan rivers (Indus, Ganges, and Brahmaputra) as well as between sub-basins within the Red River system and are attributed mainly to differences in lithology.

Verification and Improvement of the Three-Dimensional Basin Velocity Structure Model in the Osaka Sedimentary Basin, Japan Using Interstation Green's Functions and H/V Spectral Ratios of Microtremors

NASA Astrophysics Data System (ADS)

Asano, K.; Iwata, T.; Sekiguchi, H.; Somei, K.; Nishimura, T.; Miyakoshi, K.; Aoi, S.; Kunugi, T.

2012-12-01

The Osaka sedimentary basin is filled by the Plio-Pleistocene Osaka group, terrace deposits, and alluvium deposits with thickness of 1 to 2 km over the bedrock, and it is surrounded by active fault systems. The Uemachi active fault system underlies the Osaka urban area. In order to predict the strong ground motions for future events of the Uemachi fault and others, the precise basin velocity structure model is indispensable as well as the detailed source fault model. The velocity structure of the Osaka basin has been extensively investigated by using various techniques such as gravity anomaly measurements, reflection surveys, boring explorations, and microtremor measurements. Based on these surveys and ground motion simulations for observed events, the three-dimensional velocity structure models of the Osaka basin have been developed and improved for decades (e.g., Kagawa et al., 1993; Horikawa et al., 2003; Iwata et al., 2008; Iwaki and Iwata, 2011). Now we are trying to verify the velocity structure model of the Osaka basin and to improve it incorporating new data sets. We have conducted two kinds of observations in the Osaka basin. The first observation is continuous microtremor observation. We have temporarily installed three-component velocity sensors at 15 sites covering the Osaka basin to record microtremors continuously for more than one year. The seismic interferometry technique (e.g. Shapiro and Campillo, 2004) is applied to retrieve interstation Green's function for analyzing the wave propagation characteristics inside the sedimentary basin. Both Rayleigh- and Love-wave type signals are identified in 0.1-0.5 Hz from observed interstation Green's functions. The group velocities of Rayleigh and Love waves propagating between two stations are estimated from them using the multiple filter analysis method, and they are compared with the theoretical group-velocities of the model. For example, estimated Love-wave group velocity along a line inside the basin is as low as 350 m/s in 0.2-0.5 Hz. The second observation is a set of short-time (30~60 min) single-station microtremor observations to obtain H/V spectral ratios at sites. We observed microtremor at 100 strong motion stations of Osaka prefecture government, JMA, K-NET, KiK-net, and other institutes. The peak period of H/V ranges from about 1 to 7 s, and it depends on the bedrock depth at the observation site as previously pointed by Miyakoshi et al. (1997). Though the basin velocity model explains the characteristics of observed H/V spectral ratios at most sites, we found discrepancies between observed and predicted H/V peak periods at north part of Osaka bay area and hill area in southeastern part of the basin. By combining the observed constraints from the group velocities, waveform characteristics of interstation Green's functions, and H/V spectral ratios, we will improve the S-wave velocity structure model inside the Osaka basin.

Evolution of sedimentary architecture in retro-foreland basin: Aquitaine basin example from Paleocene to lower Eocene.

NASA Astrophysics Data System (ADS)

Ortega, Carole; Lasseur, Eric; Guillocheau, François; Serrano, Olivier; Malet, David

2017-04-01

The Aquitaine basin located in south western Europe, is a Pyrenean retro-foreland basin. Two main phases of compression are recorded in this retro-foreland basin during the Pyrenean orogeny. A first upper Cretaceous phase corresponding to the early stage of the orogeny, and a second one usually related to a Pyrenean paroxysmal phase during the middle Eocene. During Paleocene to lower Eocene deformations are less pronounced, interpreted as a tectonically quiet period. The aim of the study is to better constrain the sedimentary system of the Aquitaine basin during this period of Paleocene-lower Eocene, in order to discuss the evolution of the sedimentary architecture in response of the Pyrenean compression. This work is based on a compilation of a large set of subsurface data (wells logs, seismic lines and cores logs) represented by isopachs and facies map. Three main cycles were identified during this structural quiet period: (1) The Danian cycle, is recorded by the aggradation of carbonate reef-rimmed platform. This platform is characterized by proximal facies (oncoid carbonate and mudstone with thalassinoides) to the north, which leads to distal deposit facies southern (pelagic carbonate with globigerina and slump facies) and present a significant thickness variation linked to the platform-slope-basin morphology. (2) The upper Selandian-Thanetian cycle follows a non-depositional/erosional surface associated with a Selandian hiatus. The base of this cycle marked the transition between the last reef rimmed platform and a carbonate ramp. The transgressive cycle is characterized by proximal lagoon facies to the north that leads southward to distal hemipelagic facies interfingered by turbiditic Lowstand System Tracks (LST). The location of these LST is strongly controlled by inherited Danian topography. The regressive cycle ends with a major regression associated with an erosional surface. This surface is linked with a network of canyons in the north, an important terrigeneous LST and a massive erosional surface in deep basin. We correlated this upper Thanetian major regression with a flexural deformation of the basin. In this context, the importance of terrigeneous LST could be explained by the erosion of the East Pyrenean range. (3) The lower Ypresian records the installation of mixed terrigenous-carbonated system. While the East-West progradation of siliciclastic deltas is drained into foreland basin, a carbonates condensation are developed on structural ridges, attesting the structural activation of foreland basin during lower Ypresian. This study shows that Danian to middle Thanetian time represents a quiet tectonic period in the retro-foreland basin. During the upper Thanetian period, the compressive deformation is increasing, marked by the emersion of the northern platform, a massive LST in distal environment and a rise of terrigenous input in flexural basin (LST). This deformation associated with the Pyrenean compression continues during the Ypresian and highlights the paroxysm of the Pyrenean orogeny. This work is included in the Gaia project founded by TIGF, BRGM and Agence de l'Eau Adour/Garonne whose aim at constrain the nature and dynamics of deep Upper cretaceous and Tertiary aquifers of the Aquitaine basin.

Tectonics of Chukchi Sea Shelf sedimentary basins and its influence on petroleum systems

NASA Astrophysics Data System (ADS)

Agasheva, Mariia; Antonina, Stoupakova; Anna, Suslova; Yury, Karpov

2016-04-01

The Chukchi Sea Shelf placed in the East Arctic offshore of Russia between East Siberian Sea Shelf and North Slope Alaska. The Chukchi margin is considered as high petroleum potential play. The major problem is absence of core material from drilling wells in Russian part of Chukchi Shelf, hence strong complex geological and geophysical analyses such as seismic stratigraphy interpretation should be provided. In addition, similarity to North Slope and Beaufort Basins (North Chukchi) and Hope Basin (South Chukchi) allow to infer the resembling sedimentary succession and petroleum systems. The Chukchi Sea Shelf include North and South Chukchi Basins, which are separated by Wrangel-Herald Arch and characterized by different opening time. The North Chukchi basin is formed as a general part of Canada Basin opened in Early Cretaceous. The South Chukchi Basin is characterized by a transtensional origin of the basin, this deformation related to motion on the Kobuk Fault [1]. Because seismic reflections follow chronostratigraphic correlations, it is possible to achieve stratigraphic interpretation. The main seismic horizons were indicated as: PU, JU, LCU, BU, mBU marking each regional unconformities. Reconstruction of main tectonic events of basin is important for building correct geological model. Since there are no drilling wells in the North and South Chukchi basins, source rocks could not be proven. Referring to the North Chukchi basin, source rocks equivalents of Lower Cretaceous Pebble Shale Formation, Lower Jurassic Kingdak shales and Upper Triassic Shublik Formation (North Slope) is possible exhibited [2]. In the South Chukchi, it is possible that Cretaceous source rocks could be mature for hydrocarbon generation. Erosions and uplifts that could effect on hydrocarbon preservation was substantially in Lower Jurassic and Early Cretaceous periods. Most of the structures may be connected with fault and stratigraphy traps. The structure formed at Wrangel-Herald Arch to North-Chukchi through similar to well-known structure in Norwegian part of Barents Sea - Loppa High. In South Chukchi basin, the seismic wave shows interesting structures akin to diaper fold. Inversion-related anticlines and stratigraphic pinch-outs traps could presence in Cretaceous-Cenozoic cross section. As a result, we gathered and analyzed source rocks and reservoir analogs and gained improved sedimentary models in Eastern Russian Shelfs (Laptev, East Siberian and Chukchi Seas). Appropriate tectonic conditions, proven by well testing source rocks in North Slope and high thickness of basins suggest a success of hydrocarbon exploration in Russian part of Chukchi Sea Shelf. [1] Verzhbitsky V. E., S. D. Sokolov, E. M. Frantzen, A. Little, M. I. Tuchkova, and L.I. Lobkovsky, 2012, The South Chukchi Sedimentary Basin (Chukchi Sea, Russian Arctic): Age, structural pattern,and hydrocarbon potential, in D. Gao, ed., Tectonics and sedimentation: Implications for petroleum systems: AAPG Memoir 100, p.267-290. [2] Peters K. E., Magoon L. B., Bird K. J., Valin Z. C., Keller M. A. North Slope, Alaska: Source rock distribution, richness, thermal maturity, and petroleum charge AAPG Bulletin, V. 90, No. 2 (February 2006), 2006, P. 261-292.

Reflection Response of the Parnaíba Basin (NE Brazil) from Seismic Ambient Noise Autocorrelation Functions

NASA Astrophysics Data System (ADS)

Julià, Jordi; Schimmel, Martin; Cedraz, Victória

2017-04-01

Reflected-wave interferometry relies on the recording of transient seismic signals from random wavefields located beneath recording stations. Under vertical incidence, the recordings contain the full transmission response, which includes the direct wave as well as multiple reverberations from seismic discontinuities located between the wavefields and the receiver. It has been shown that, under those assumptions, the reflection response of the medium can be recovered from the autocorrelation function (ACF) of the transmission response at a given receiver, as if the wavefields had originated themselves at the free surface. This passive approach to seismic reflection profiling has the obvious advantage of being low-cost and non-invasive when compared to its active-source counterpart, and it has been successfully utilized in other sedimentary basins worldwide. In this paper we evaluate the ability of the autocorrelation of ambient seismic noise recorded in the Parnaíba basin - a large Paleozoic basin in NE Brazil - to recover the reflection response of the basin. The dataset was acquired by the Universidade Federal do Rio Grande do Norte during 2015 and 2016 under the Parnaíba Basin Analysis Project (PBAP), a multi-disciplinary and multi-institutional effort funded by BP Energy do Brasil aimed at improving our current understanding of the architecture of this cratonic basin. The dataset consists of about 1 year of continuous ground motion data from 10 short-period, 3-component stations located in the central portion of the basin. The stations were co-located with an existing (active-source) seismic reflection profile that was shot in 2012, making a linear array of about 100 km in aperture and about 10 km inter-station spacing. To develop the autocorrelation at a given station we considered the vertical component of ground motion only, which should result in the P-wave response. The vertical recordings were first split into 10 min-long windows, demeaned, de-trended, re-sampled, and band-pass filtered between 8 and 16 Hz before autocorrelation, and then stacked with phase-weighting to enhance coherency of the retrieved signal. The ACFs show coherent signal is recovered at lag times between 0.5 and 2 s, which we interpret as P- and S-wave energy reflected on top of an intra-sedimentary discontinuity. Our results are consistent, to first-order, with a previously developed active-source reflection response of the basin.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiercelin, J.J.; Lezzar, K.E.; Richert, J.P.

Oil is known from lacustrine basins of the east African rift. The geology of such basins is complex and different depending on location in the eastern and western branches. The western branch has little volcanism, leading to long-lived basins, such as Lake Tanganyika, whereas a large quantity of volcanics results in the eastern branch characterized by ephemeral basins, as the Baringo-Bogoria basin in Kenya. The Baringo-Bogoria basin is a north-south half graben formed in the middle Pleistocene and presently occupied by the hypersaline Lake Bogoria and the freshwater Lake Baringo. Lake Bogoria is fed by hot springs and ephemeral streamsmore » controlled by grid faults bounding the basin to the west. The sedimentary fill is formed by cycles of organic oozes having a good petroleum potential and evaporites. On the other hand, and as a consequence of the grid faults, Lake Baringo is fed by permanent streams bringing into the basin large quantities of terrigenous sediments. Lake Tanganyika is a meromictic lake 1470 m deep and 700 km long, of middle Miocene age. It is subdivided into seven asymmetric half grabens separated by transverse ridges. The sedimentary fill is thick and formed by organic oozes having a very good petroleum potential. In contrast to Bogoria, the lateral distribution of organic matter is characterized by considerable heterogeneity due to the existence of structural blocks or to redepositional processes.« less

Geology and petroleum resources of Venezuela

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klemme, H.D.

1986-05-01

Venezuela occupies a peripheral position to the Guiana shield and craton in northern South America. The larger sedimentary basins of the Venezuelan craton zone are marginal cratonic basins (Lanos-Barinas), resulting from Tertiary Andean eastward movements, and basins formed by collisional, extensional, and transformed movement of the American portion of Tethys (eastern Venezuela-Trinidad). The smaller sedimentary basins of Venezuela are Tertiary transverse-wrench basins in the disturbed intermontane zone peripheral to the cratonic basins (Maracaibo, Falcon, parts of the Gulf of Venezuela, Carioca, and parts of Tobago-Margarita). Venezuela accounts for 75% of the recoverable oil and 55% of the gas discovered inmore » South America. These deposits occur primarily in two basins (East Venezuela and Maracaibo - where one complex, the Bolivar Coastal and lake pools, represents 40% of South American discovered oil). The East Venezuela basin contains the Orinico heavy oil belt, currently assessed at 1 to 2 trillion bbl of oil in place. Source rocks for Venezuelan hydrocarbons are middle Cretaceous calcareous bituminous shales and marls (40% of discovered hydrocarbons), lower Tertiary deltaic and transitional shales, Paleocene-Eocene (40%), and Oligocene-Miocene deltaic and coastal shales (20%). A key factor in high recovery of hydrocarbons appears to be preservation of middle Cretaceous and lower Tertiary source rocks during maturation and migration. Reservoirs are dominantly (> 90%) clastic sediments (sandstones) within, above, or updip from source sequences. Cap rocks are interbedded and overlying shale.« less

Genesis of Miocene litho-stratigraphic trap and hydrocarbon accumulation in the Qiongdongnan Basin, northern South China Sea

NASA Astrophysics Data System (ADS)

Fan, Caiwei; Jiang, Tao; Liu, Kun; Tan, Jiancai; Li, Hu; Li, Anqi

2018-12-01

In recent years, several large gas fields have been discovered in western Qiongdongnan Basin. It is important and necessary to illustrate their sedimentary characteristics and hydrocarbon migration so that more gas fields could be discovered in the future. Previous regional tectonic-sedimentary researchers show that large-scale source rock of the Yacheng Formation developed in the Ledong and Lingshui sags due to the Red River Fault pull-apart strike slip in early Oligocene. The main targets for hydrocarbon exploration in this area are the Miocene deep water reservoirs. In late Miocene, the Huangliu Formation reservoirs are composed of the early channels which were sourced by river systems in Hainan uplift and the consequent channels were sourced by Qiupen River in Kunsong uplift. Both axial channels exhibit unique spatial distribution patterns and geometries. The other kind of reservoir developed in the middle Miocene Meishan Formation, which compose of slope break-controlled submarine fan. They can be further classified into three types—slope channelized fan, basin floor fan, and bottom current reworked fan. The various fans have different reservoir quality. These two kinds of reservoirs contribute to four types of litho-stratigraphic traps under the actions of sedimentation and subsidence. The overpressure caused by hydrocarbon generation can fracture deeper strata and result in regional fractured network for hydrocarbon migration. Therefore, free gas driven by overpressure and buoyancy force can be migrated into Miocene litho-stratigraphic traps to accumulate. The revealed genesis of Miocene lithologic trap and hydrocarbon accumulation in the Qiongdongnan Basin would greatly contribute to the further hydrocarbon exploration in northern South China Sea and can be helpful for other deep water areas around the world.

Stress Map 2.0: Updating the Stress Map of the Western Canadian Sedimentary Basin

NASA Astrophysics Data System (ADS)

Mallyon, D.; Schmitt, D. R.; Currie, C. A.; Gu, Y. J.; Heidbach, O.

2015-12-01

The greatest horizontal compression in much of the Western Canada Sedimentary Basin appears to uniformly trend NE-SW. Beyond this, major gaps remain in our knowledge of stress magnitudes and even faulting regimes. This lack of quantitative information impedes a proper understanding of seismic events that appear to be linked to hydraulic fracturing stimulations. Apart from this immediate concern, such seismicity could impact long term green-house gas sequestration and geothermal energy development. As part of the Helmholtz-Alberta geothermal collaboration, we are developing a program to update this crustal stress state information. The program consists of more immediate studies related to conventional analysis of borehole image logs, core fractures, and transient pressure records as can be made available. Data sets analyzed to date include logs to 3.5 km depth from areas experiencing induced seismicity, from 2.5 km depth within the Precambrian craton in NE Alberta, and to 400 m depth within a large carbonate platform. All these data largely confirm the NE-SW stress directions. In some cases, the configurations of drilling induced tensile fractures and borehole breakouts allow the faulting regime to be constrained. The addition of new seismometers to the region is also allowing for the refinement of earthquake focal mechanisms. Finally, a dramatic contrast in lithosphere thickness, composition and geothermal gradient exists at the contact between the Cordillera and the North American craton; therefore, lithosphere-scale numerical models are also being developed to quantify the relative contribution of geodynamic processes, such as mantle flow and contact geometry, to the observed stress regime within the basin.

Mechanisms Of Saucer-Shaped Sill Emplacement: Insight From Experimental Modeling

NASA Astrophysics Data System (ADS)

Galland, O.; Planke, S.; Malthe-Sørenssen, A.; Polteau, S.; Svensen, H.; Podladchikov, Y. Y.

2006-12-01

It has been recently demonstrated that magma intrusions in sedimentary basins had a strong impact on petroleum systems. Most of these intrusions are sills, and especially saucer-shaped sills. These features can be observed in many sedimentary basins (i.e. the Karoo basin, South Africa; the Norwegian and North Sea; the Tunguska basin, Siberia; the Neuquén basin in Argentina). The occurrence of such features in so various settings suggests that their emplacement results from fundamental processes. However, the mechanisms that govern their formation remain poorly constrained. Experiments were conducted to simulate the emplacement of saucer-shaped magma intrusions in sedimentary basins. The model rock and magma were fine-grained silica flour and molten vegetable oil, respectively. This modeling technique allows simultaneous simulation of magma emplacement and brittle deformation at a basin scale. For our purpose, we performed our experiments without external deformation. During the experiments, the oil was injected horizontally at constant flow rate within the silica flour. Then the oil initially emplaced in a sill, whereas the surface of the model inflated into a smooth dome. Subsequently, the oil propagated upwards along inclined sheets, finally reaching the surface at the edge of the dome. The resulting geometries of the intrusions were saucer-shaped sills. Then the oil solidified, and the model was cut in serial cross-sections through which the structures of the intrusive body and of the overburden can be observed. In order to constraint the processes governing the emplacement of such features, we performed a parametric study based on a set of experiments in which we systematically varied parameters such as the depth of emplacement and the injection flow rate of the oil. Our results showed that saucer diameters are larger at deeper level of emplacement. Opposite trend was obtained with varying injection flow rates. Based on our results, we conducted a detailed physical analysis that resulted in the definition of a dimensionless parameter that governs the emplacement of saucers.

Geological evaluation of Radarsat data: Plans and preliminary results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berger, Z.; Irving, R.E.L.; Thompson, M.D.

1996-01-01

Radarsat, the Canadian synthetic aperture radar satellite to be launched in September 1995, is anticipated to become the prime active imaging system for geological mapping of tropical areas and other humid areas. Radarsat will provide adequate spatial resolution, stereo capabilities and relatively low incidence angles to reduce the geometric distortions of geological structures due to layover effects. As part of the Radarsat User Development Program of the Canadian Space Agency, it has been proposed to conduct an evaluation program of the terrain surface mapping capabilities of Radarsat and its application to hydrocarbon exploration, coal development, geological hazard mapping and environmentalmore » monitoring. The evaluation program will be carried out in three test sites: (1) Western Canadian Basin (a mature exploration area in Alberta with a range of geology/topography), (2) Andean Foothills (frontier tropical sedimentary basins in Columbia representing prototype active exploration areas), and (3) Philippine volcanic region (frontier tropical earthquake-prone geohazard area of Philippine wrench fault system on Luzon Island, in a typical structural setting of the sedimentary basins of southeast Asia). The paper will include the project plans, illustrate the structural setting and the relationships between surface and subsurface structures for each of the three test sites, and present a preliminary evaluation of simulated and actual Radarsat data as compared to data from ERS-1, airborne SAR, Landsat Thematic Mapper and SPOT. The preliminary application of Radarsat for exploration will be discussed.« less

Geological evaluation of Radarsat data: Plans and preliminary results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berger, Z.; Irving, R.E.L.; Thompson, M.D.

1996-12-31

Radarsat, the Canadian synthetic aperture radar satellite to be launched in September 1995, is anticipated to become the prime active imaging system for geological mapping of tropical areas and other humid areas. Radarsat will provide adequate spatial resolution, stereo capabilities and relatively low incidence angles to reduce the geometric distortions of geological structures due to layover effects. As part of the Radarsat User Development Program of the Canadian Space Agency, it has been proposed to conduct an evaluation program of the terrain surface mapping capabilities of Radarsat and its application to hydrocarbon exploration, coal development, geological hazard mapping and environmentalmore » monitoring. The evaluation program will be carried out in three test sites: (1) Western Canadian Basin (a mature exploration area in Alberta with a range of geology/topography), (2) Andean Foothills (frontier tropical sedimentary basins in Columbia representing prototype active exploration areas), and (3) Philippine volcanic region (frontier tropical earthquake-prone geohazard area of Philippine wrench fault system on Luzon Island, in a typical structural setting of the sedimentary basins of southeast Asia). The paper will include the project plans, illustrate the structural setting and the relationships between surface and subsurface structures for each of the three test sites, and present a preliminary evaluation of simulated and actual Radarsat data as compared to data from ERS-1, airborne SAR, Landsat Thematic Mapper and SPOT. The preliminary application of Radarsat for exploration will be discussed.« less

Tectonic implications of Mesozoic magmatism to initiation of Cenozoic basin development within the passive South China Sea margin

NASA Astrophysics Data System (ADS)

Mai, Hue Anh; Chan, Yu Lu; Yeh, Meng Wan; Lee, Tung Yi

2018-04-01

The South China Sea (SCS) is one of the classical example of a non-volcanic passive margin situated within three tectonic plates of the Eurasian, Indo-Australian and Philippine Sea plate. The development of SCS resulted from interaction of various types of plate boundaries, and complex tectonic assemblage of micro blocks and accretionary prisms. Numerous models were proposed for the formation of SCS, yet none can fully satisfy different aspects of tectonic forces. Temporal and geographical reconstruction of Cretaceous and Cenozoic magmatism with the isochrones of major basins was conducted. Our reconstruction indicated the SE margin of Asia had gone through two crustal thinning events. The sites for rifting development are controlled by localized thermal weakening of magmatism. NW-SE extension setting during Late Cretaceous revealed by magmatism distribution and sedimentary basins allow us to allocate the retreated subduction of Pacific plate to the cause of first crustal thinning event. A magmatic gap between 75 and 65 Ma prior to the initiation of first basin rifting suggested a significant modification of geodynamic setting occurred. The Tainan basin, Pearl River Mouth basin, and Liyue basins started to develop since 65 Ma where the youngest Late Cretaceous magmatism concentrated. Sporadic bimodal volcanism between 65 and 40 Ma indicates further continental extension prior to the opening of SCS. The E-W extension of Malay basin and West Natuna began since late Eocene followed by N-S rifting of SCS as Neotethys subducted. The SCS ridge developed between Pearl River Mouth basin and Liyue basin where 40 Ma volcanic activities concentrated. The interaction of two continental stretching events by Pacific followed by Neotethys subduction with localized magmatic thermal weakening is the cause for the non-volcanic nature of SCS.

Revised stratigraphy and reinterpretation of the Miocene Pohang basinfill, SE Korea: sequence development in response to tectonism and eustasy in a back-arc basin margin

NASA Astrophysics Data System (ADS)

Sohn, Y. K.; Rhee, C. W.; Shon, H.

2001-09-01

The Miocene Pohang Basin is a pull-apart basin formed along the eastern continental margin of Korea (ECMK) during the back-arc opening of the East Sea (Sea of Japan). The basin is filled by more than 1 km thick, nonmarine to deep-marine strata. These strata show extreme vertical and lateral lithofacies changes and have caused decades-long controversies on their nature and stratigraphy. Previous sedimentological studies suggest that the basinfill was deposited by a series of contemporaneously developed depositional systems, including fan delta, prodelta, slope apron, and basin plain. Detailed mapping and magnetotelluric surveying show, however, that the basinfill is composed of several packages of strata (sequences) that are bounded by distinct and laterally persistent stratigraphic discontinuities (sequence boundaries). This suggests that the depositional systems in the Pohang Basin developed sequentially rather than contemporaneously. Six packages of strata are identified in the basin: a nonmarine to shallow marine (transgressive) sequence (Sequence 1), a Gilbert-type-delta conglomerate (Sequence 2), and alternations of submarine conglomerates and hemipelagic mudstones (Sequences 3-6). The conglomerates and hemipelagic mudstones of the latter four sequences are interpreted to represent lowstand depositional systems (slope apron, submarine fan, and high-gradient delta) and condensed intervals, respectively. Compilation of geochronologic, paleomagnetic, and biostratigraphic data suggests that Sequence 1 formed during the gradual subsidence of the ECMK prior to 17 Ma, whereas Sequence 2 formed in response to abrupt downfaulting of the Pohang Basin at about 17 Ma. Both sequences are interpreted to have developed in response to the early Miocene back-arc-opening tectonism of the East Sea. On the other hand, Sequences 3-6 formed between 17 and about 10.5 Ma. The Pohang Basin was subject to only minor tectonism during this period and could record global sea-level fluctuations. We suggest that the four alternations of conglomerates (lowstand systems) and hemipelagic mudstones (condensed intervals) resulted most probably from the 3rd-order glacioeustatic cycles during the middle Miocene. This finding implies that the signatures of global sea-level fluctuations can be deciphered from a tectonically active sedimentary basin if the timing of regional tectonic development is well constrained, and the global sea-level chart of Haq et al. ( Haq, B.W., Hardenbol, J., Vail, P.R., 1987, Chronology of fluctuating sea levels since the Triassic. Science 235, 1156-1167; Haq, B.U., Hardenbol, J., Vail, P.R., 1988. Mesozoic and Cenozoic chronostratigraphy and eustatic cycles. In: Wilgus, C.K., Hastings, B.S., Posamentier, H., Van Wagoner, J., Ross, C.A., Kendall, C.G.S.C. (Eds.), Sea-Level Changes: an Integrated Approach: Soc. Econ. Paleont. Mineral. Spec. Publ. 42, pp. 71-108) may serve as a guide to basinfill interpretation even in tectonically active sedimentary basins.

Structural evolution and petroleum productivity of the Baltic basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ulmishek, G.F.

The Baltic basin is an oval depression located in the western part of the Russian craton; it occupies the eastern Baltic Sea and adjacent onshore areas. The basin contains more than 5,000 m of sedimentary rocks ranging from latest Proterozoic to Tertiary in age. These rocks consist of four tectonostratigraphic sequences deposited during major tectonic episodes of basin evolution. Principal unconformities separate the sequences. The basin is underlain by a rift probably filled with Upper Proterozoic rocks. Vendian and Lower Cambrian rocks (Baikalian sequence) form two northeast-trending depressions. The principal stage of the basin development was during deposition of amore » thick Middle Cambrian-Lower Devonian (Caledonian) sequence. This stage was terminated by the most intense deformations in the basin history. The Middle Devonian-Carboniferous (Hercynian) and Permian-Tertiary (Kimmerian-Alpine) tectonic and depositional cycles only slightly modified the basin geometry and left intact the main structural framework of underlying rocks. The petroleum productivity of the basin is related to the Caledonian tectonostratigraphic sequence that contains both source rocks and reservoirs. However, maturation of source rocks, migration of oil, and formation of fields took place mostly during deposition of the Hercynian sequence.« less

Tectonic evolution of the Arizaro basin of the Puna plateau, NW Argentina: Implications for plateau-scale processes

NASA Astrophysics Data System (ADS)

Boyd, John D.

Sedimentary basins of the Altiplano-Puna Plateau within the Andean Plateau in South America contain the record of retro-arc foreland basin evolution during the Cenozoic. The deformation of these basins is characterized by high angle reverse faults and thrusts deforming crystalline basement and sedimentary covers. The mechanism/s responsible for deformation within the region are not fully understood in detail. The relative abundance of intercalated tuffs within these basins and those within the bounding Eastern Cordillera enables the spatial-temporal pattern of deformation across the orogen to be constrained. This study uses the systematic combination of structural, geochronologic and sedimentalogical techniques applied to Cenozoic sedimentary rocks within the Arizaro Basin to investigate the timing of deformation across within the region in order to test two end member models for basin deformation in response to lithospheric processes. The first model attributes the deformation of the basins to internal deformation within an orogenic wedge as part of the taper building process required prior to propagation eastward towards the foreland basin system. The second model attributes basin deformation to isostatic adjustments resulting from small-scale lithospheric foundering. Detailed geologic mapping of the Arizaro Basin reveals a complex interplay of coeval thick-skinned and thin-skinned deformation, which deforms the thick Miocene succession of fluvial-lacustrine strata in both a brittle and ductile manner. Zircon U-Pb analyses of intercalated tuffs from the Vizcachera Formation reveal that approximately three km of the section was deposited between the Early Miocene (ca. 18.3) and the Middle Miocene (ca. 13.9). One tuff in the uppermost Vizcachera Formation constrains the lower limit of timing of deformation for the Arizaro Basin to be 13.9 +/- 0.7 Ma. When combined with published geochronological data across the Puna Plateau and Eastern Cordillera, the new data presented in this study constrains timing of deformation within the basin and the greater Arizaro area to the Middle Miocene. This study also indicates that the spatial-temporal patterns of deformation are likely the result of a combination of both models mentioned above with critical taper theory dominating early deformation associated with basin formation and small-scale lithospheric foundering dominating the later deformation in the Middle Miocene. Deformation at the wedge tip continues in the Eastern Cordillera seemingly without interruption, suggesting that the effects of the isostatic pull-down associated with small-scale lithospheric foundering is localized and does not significantly affect the taper of the orogenic wedge as a whole. Thus, allowing the normal cycle of orogenic wedge propagation to occur, uninhibited.

Structural and sedimentary evolution of the Malay Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ismail, M.T.; Rudolph, K.W.; Abdullah, S.A.

1994-07-01

The Malay Basin is a back-arc basin that formed via Eocene ( ) through Oligocene extension. This early extensional episode is characterized by large east-west and northwest-southeast-trending normal fault systems with associated block rotation. Extensional subbasins are filled with a thick succession of alluvial and fluvial sediments that show increasing lacustrine influence toward the central basin dep. In the early Miocene, the basin entered a passive sag phase in which depositional relief decreased, and there is the first evidence of widespread marine influence. Lower Miocene sediments consist of cyclic offshore marine, tidal-estuarine, and coastal plain fluvial sediments with very widemore » facies tracts. The middle Miocene is dominated by increasing compressional inversion, in which preexisting extensional lows were folded into east-west anticlines. This compression continues well into the Pliocene-Pleistocene, especially in the northwest portion of the basin and is accompanied by an increase in basin-wide subsidence. There is significant thinning over the crest of the growing anticlines and an angular unconformity near the top of the middle Miocene in the southeast portion of the basin. Middle Miocene sedimentary facies are similar to those seen in the lower Miocene, but are influenced by the contemporaneous compressional folding and normal faulting. Based on this study, there is no evidence of through-going wrench-fault deformation in the Malay Basin. Instead, localized strike-slip faulting is a subsidiary phenomenon associated with the extensional and compressional tectonic episodes.« less

Sedimentary architecture of a sub-lacustrine debris fan: Eocene Dongying Depression, Bohai Bay Basin, east China

NASA Astrophysics Data System (ADS)

Liu, Jianping; Xian, Benzhong; Wang, Junhui; Ji, Youliang; Lu, Zhiyong; Liu, Saijun

2017-12-01

The sedimentary architectures of submarine/sublacustrine fans are controlled by sedimentary processes, geomorphology and sediment composition in sediment gravity flows. To advance understanding of sedimentary architecture of debris fans formed predominantly by debris flows in deep-water environments, a sub-lacustrine fan (Y11 fan) within a lacustrine succession has been identified and studied through the integration of core data, well logging data and 3D seismic data in the Eocene Dongying Depression, Bohai Bay Basin, east China. Six types of resedimented lithofacies can be recognized, which are further grouped into five broad lithofacies associations. Quantification of gravity flow processes on the Y11 fan is suggested by quantitative lithofacies analysis, which demonstrates that the fan is dominated by debris flows, while turbidity currents and sandy slumps are less important. The distribution, geometry and sedimentary architecture are documented using well data and 3D seismic data. A well-developed depositional lobe with a high aspect ratio is identified based on a sandstone isopach map. Canyons and/or channels are absent, which is probably due to the unsteady sediment supply from delta-front collapse. Distributary tongue-shaped debris flow deposits can be observed at different stages of fan growth, suggesting a lobe constructed by debrite tongue complexes. Within each stage of the tongue complexes, architectural elements are interpreted by wireline log motifs showing amalgamated debrite tongues, which constitute the primary fan elements. Based on lateral lithofacies distribution and vertical sequence analysis, it is proposed that lakefloor erosion, entrainment and dilution in the flow direction lead to an organized distribution of sandy debrites, muddy debrites and turbidites on individual debrite tongues. Plastic rheology of debris flows combined with fault-related topography are considered the major factors that control sediment distribution and fan architecture. An important implication of this study is that a deep-water depositional model for debrite-dominated systems was proposed, which may be applicable to other similar deep-water environments.

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

USGS Publications Warehouse

Shimeld, John; Li, Qingmou; Chian, Deping; Lebedeva-Ivanova, Nina; Jackson, Ruth; Mosher, David; Hutchinson, Deborah R.

2016-01-01

The Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is encoded in seismic wide-angle reflections and refractions recorded with expendable sonobuoys between 2007 and 2011. Velocity–depth samples within the sedimentary succession are extracted from published analyses for 142 of these records obtained at irregularly spaced stations across an area of 1.9E + 06 km2. The samples are modelled at regional, subregional and station-specific scales using an exponential function of inverse velocity versus depth with regionally representative parameters determined through numerical regression. With this approach, smooth, non-oscillatory velocity–depth profiles can be generated for any desired location in the study area, even where the measurement density is low. Practical application is demonstrated with a map of sedimentary thickness, derived from seismic reflection horizons interpreted in the time domain and depth converted using the velocity–depth profiles for each seismic trace. A thickness of 12–13 km is present beneath both the upper Mackenzie fan and the middle slope off of Alaska, but the sedimentary prism thins more gradually outboard of the latter region. Mapping of the observed-to-predicted velocities reveals coherent geospatial trends associated with five subregions: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. Comparison of the subregional velocity–depth models with published borehole data, and interpretation of the station-specific best-fitting model parameters, suggests that sandstone is not a predominant lithology in any of the five subregions. However, the bulk sand-to-shale ratio likely increases towards the Mackenzie fan, and the model for this subregion compares favourably with borehole data for Miocene turbidites in the eastern Gulf of Mexico. The station-specific results also indicate that Quaternary sediments coarsen towards the Beaufort-Mackenzie and Banks Island margins in a manner that is consistent with the variable history of Laurentide Ice Sheet advance documented for these margins. Lithological factors do not fully account for the elevated velocity–depth trends that are associated with the southwestern Canada Basin and the Alpha-Mendeleev magnetic domain. Accelerated porosity reduction due to elevated palaeo-heat flow is inferred for these regions, which may be related to the underlying crustal types or possibly volcanic intrusion of the sedimentary succession. Beyond exploring the variation of an important physical property in the Arctic Ocean basin, this study provides comparative reference for global studies of seismic velocity, burial history, sedimentary compaction, seismic inversion and overpressure prediction, particularly in mudrock-dominated successions.

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

NASA Astrophysics Data System (ADS)

Shimeld, John; Li, Qingmou; Chian, Deping; Lebedeva-Ivanova, Nina; Jackson, Ruth; Mosher, David; Hutchinson, Deborah

2016-01-01

The Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is encoded in seismic wide-angle reflections and refractions recorded with expendable sonobuoys between 2007 and 2011. Velocity-depth samples within the sedimentary succession are extracted from published analyses for 142 of these records obtained at irregularly spaced stations across an area of 1.9E + 06 km2. The samples are modelled at regional, subregional and station-specific scales using an exponential function of inverse velocity versus depth with regionally representative parameters determined through numerical regression. With this approach, smooth, non-oscillatory velocity-depth profiles can be generated for any desired location in the study area, even where the measurement density is low. Practical application is demonstrated with a map of sedimentary thickness, derived from seismic reflection horizons interpreted in the time domain and depth converted using the velocity-depth profiles for each seismic trace. A thickness of 12-13 km is present beneath both the upper Mackenzie fan and the middle slope off of Alaska, but the sedimentary prism thins more gradually outboard of the latter region. Mapping of the observed-to-predicted velocities reveals coherent geospatial trends associated with five subregions: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. Comparison of the subregional velocity-depth models with published borehole data, and interpretation of the station-specific best-fitting model parameters, suggests that sandstone is not a predominant lithology in any of the five subregions. However, the bulk sand-to-shale ratio likely increases towards the Mackenzie fan, and the model for this subregion compares favourably with borehole data for Miocene turbidites in the eastern Gulf of Mexico. The station-specific results also indicate that Quaternary sediments coarsen towards the Beaufort-Mackenzie and Banks Island margins in a manner that is consistent with the variable history of Laurentide Ice Sheet advance documented for these margins. Lithological factors do not fully account for the elevated velocity-depth trends that are associated with the southwestern Canada Basin and the Alpha-Mendeleev magnetic domain. Accelerated porosity reduction due to elevated palaeo-heat flow is inferred for these regions, which may be related to the underlying crustal types or possibly volcanic intrusion of the sedimentary succession. Beyond exploring the variation of an important physical property in the Arctic Ocean basin, this study provides comparative reference for global studies of seismic velocity, burial history, sedimentary compaction, seismic inversion and overpressure prediction, particularly in mudrock-dominated successions.

Late Miocene/Pliocene Ostracod Biostratigraphy from South Carpathian Foredeep, Romania (Badislava-Topolog Area)

NASA Astrophysics Data System (ADS)

Floroiu, Alina; Stoica, Marius; Vasiliev, Iuliana; Krijgsman, Wout

2016-04-01

The Paratethys epicontinental sea has been an essential paleogeographic feature defining the Eurasian interior since Oligocene. By the end of the Miocene, ongoing tectonic activity in the region determined severe restrictions of the connection of the large former Paratethys sea resulting in the formation of several smaller subbasins: the Pannonian basin, the Dacian basin, the Black Sea and the Caspian Sea. In the western part of the Dacian Basin, the thick and continuous Mio-Pliocene sedimentary successions of the Getic Depression of Romania provide an exceptional opportunity to study the paleoecological changes in the Eastern Paratethys during the time when the Mediterranean and Black Sea experienced important sea level changes related to the Messinian Salinity Crisis. These sedimentary successions were the basis of high-resolution magnetobiostratigraphic studies that allow a detailed correlation to the Geological Time Scale. Here, we present the main characteristics of the ostracod assemblages of the Late Miocene/Pliocene sedimentary succession from Badislava-Topolog section covering the Eastern Paratethys regional Maeotian and Pontian, stages that are, at moment, under ongoing formal stratigraphic definition process. The Mio-Pliocene is exposed in the central part of the Getic Depression, especially Topolog-Arges area, where it riches up to 500 m in thickness being incorporated into a large monocline structure with 15o-20o plungeto the south. The Upper Maeotian deposits from the area have developed mainly in fluviatile-deltaic facies with frequent continental intercalations. The ostracod assemblage is represented by rare fresh water ostracods of Candona, Pseudocandona and Ilyocypris genera, capable to populate unstable environments like flood-plains, lakes and rivers with temporary existence. The scarce Maeotian ostracod fauna from this marginal section differs essentially from the more diversified one of the same age recorded in areas that evolved in basinal conditions. The top of the Maeotian sequence is marked by an erosional surface. The overlaying Pontian has a transgressive character being represented only by the Late Pontian (Bosphorian) fining-upward sedimentary sequence that starts with coarse to medium-grained pebbles and sands in the lower part, passing to predominant pelitic deposits to the upper part. These Bosphorian, fine-grained sedimentary rocks provided a rich ostracods fauna represented mainly by species of Pontoniella, Camptocypria, Caspiocypris, Cypria, Amplocypris, Bakunella Tyrrhneocythere, Amnicythere, Loxoconcha and Amnicythere. There are no indications for the presence of the Lower and Middle Pontian (Odessian and Portaferrian) substages in the investigated area, the Upper Pontian deposits discordantly overlying the Upper Maeotian sediments. The transition to the Dacian stage (Lower Pliocene) is more gradual, some of Pontian species passing to the Lower Dacian (Getian) where they are in association with typical Dacian ostracods.

Interpretation of Gravimetric and Aeromagnetic Data of the Tecoripa Chart in Southeast Sonora, Mexico.

NASA Astrophysics Data System (ADS)

Martínez-Retama, S.; Montaño-Del Cid, M. A.

2015-12-01

The Tecoripa chart H12-D64 is located southeast of the state of Sonora, México, south of Arizona. The geology is represented by sedimentary rocks of the Ordovician and Triassic, volcanic rocks of the Upper Cretaceous and Tertiary, intrusive rocks from the Upper Cretaceous- Tertiary and sedimentary rocks of the Cenozoic. In this paper a gravimetric study was conducted to determine the configuration and depth of the basement and to develop a structural model of the subsurface. For this purpose a consistent gravimetric survey in 3 profiles was conducted. To complement this study, gravimetric data obtained by INEGI (96 gravimetric stations spaced every 4000 m) that correspond to a regional survey was also used. The two sets of data were corrected and processed with the WinGLink software. The profiles were then modeled using the Talwani method. 4 Profiles corresponding to the gravimetric survey and 5 data profiles from INEGI were modeled. Aeromagnetic data from the total field of Tecoripa chart were also processed. The digital information was integrated and processed by generating a data grid. Processes applied to data consisted of reduction to the pole, regional-residual separation and upward continuations. In general, the obtained structural models show intrusive bodies associated with well-defined high gravimetric and magnetic and low gravimetric and magnetic are associated with basins and sedimentary rocks. The obtained geological models show the basement represented by volcanic rocks of the Tarahumara Formation from the Upper Cretaceous which are in contact with sedimentary rocks from the Barranca Group from Upper Cretaceous and limestones from the Middle Ordovician. Both volcanic and sedimentary rocks are intruded by granodiorite- granite with ages of the Tertiary-Oligocene. Based on the superficial geology as well as in the configuration of the basement and the obtained structural model the existence of faults with NW-SE orientation that originate Horst and Graben type structures can be inferred. The basins have depths of 2,000 to 4,000m with sedimentary fillings from the Báucarit Formation and Quaternary sediments.

Sedimentation as a Control for Large Submarine Landslides: Mechanical Modeling and Analysis of the Santa Barbara Basin

NASA Astrophysics Data System (ADS)

Stoecklin, A.; Friedli, B.; Puzrin, A. M.

2017-11-01

The volume of submarine landslides is a key controlling factor for their damage potential. Particularly large landslides are found in active sedimentary regions. However, the mechanism controlling their volume, and in particular their thickness, remains unclear. Here we present a mechanism that explains how rapid sedimentation can lead to localized slope failure at a preferential depth and set the conditions for the emergence of large-scale slope-parallel landslides. We account for the contractive shearing behavior of the sediments, which locally accelerates the development of overpressures in the pore fluid, even on very mild slopes. When applied to the Santa Barbara basin, the mechanism offers an explanation for the regional variation in landslide thickness and their sedimentation-controlled recurrence. Although earthquakes are the most likely trigger for these mass movements, our results suggest that the sedimentation process controls the geometry of their source region. The mechanism introduced here is generally applicable and can provide initial conditions for subsequent landslide triggering, runout, and tsunami-source analyses in sedimentary regions.

Low-Temperature Hydrothermal Resource Potential

DOE Data Explorer

Katherine Young

2016-06-30

Compilation of data (spreadsheet and shapefiles) for several low-temperature resource types, including isolated springs and wells, delineated area convection systems, sedimentary basins and coastal plains sedimentary systems. For each system, we include estimates of the accessible resource base, mean extractable resource and beneficial heat. Data compiled from USGS and other sources. The paper (submitted to GRC 2016) describing the methodology and analysis is also included.

A case study on pseudo 3-D Chirp sub-bottom profiler (SBP) survey for the detection of a fault trace in shallow sedimentary layers at gas hydrate site in the Ulleung Basin, East Sea

NASA Astrophysics Data System (ADS)

Kim, Young-Jun; Koo, Nam-Hyung; Cheong, Snons; Kim, Jung-Ki; Chun, Jong-Hwa; Shin, Sung-Ryul; Riedel, Michael; Lee, Ho-Young

2016-10-01

A pseudo 3-D Chirp sub-bottom profiler (SBP) survey was conducted to define the extension of a fault that was previously identified on low-resolution 2-D seismic data with an emphasis on the shallow sedimentary layers and to determine if the fault extends to the seafloor. The geophysical survey was conducted as part of an environmental impact assessment for a proposed gas hydrate production test in the Ulleung Basin, East Sea. The Chirp SBP raw data were acquired over an area of 1 km × 1 km with an average line spacing of 20 m. To produce a 3-D Chirp SBP volume, we developed an optimal processing sequence that was divided into two steps. The first phase of 2-D data processing included a sweep signature estimation, correlation, deconvolution, swell effect correction, and migration. The second phase of 3-D data processing was composed of a bin design, bin gathering of the final processed 2-D data set, amplitude normalization, and residual statics correction. The 3-D Chirp SBP volume provides enhanced imaging especially due to the residual static processing using a moving average method and shows better continuity of the sedimentary layers and consistency of the reflection events than the individual 2-D lines. Deformation of the seafloor as a result of the fault was detected, and the fault offset increases in the deeper sedimentary layers. We also determined that the fault strikes northwest-southeast. However, the shallow sub-seafloor sediments have high porosities and therefore do not exhibit brittle fault-behavior but rather deform continuously due to fault movement.

Capability of ERTS-1 imagery to investigate geological and structural features in a sedimentary basin (Bassin Parisien, France)

NASA Technical Reports Server (NTRS)

Cavelier, C.; Scanvic, J. Y.; Weecksteen, G.; Zizerman, A.

1973-01-01

A preliminary study of the MSS imagery of a sedimentary basin whose structure is regular is reported. Crops and natural vegetation are distributed all over the site located under temperate climate. Ground data available concern plant species geology and tectonic and are correlated with results from ERTS 1 imagery. This comparison shows a good correlation. The main geological units are detected or enhanced by way of agricultural land use and/or natural vegetation. Alluvial deposits are outlined by vegetation grass land and poplar trees. Some spatial relationship of geostructures, suspected until now, are identified or extended in associating results from different spectral bands.

Holocene depocenter migration and sediment accumulation in Delaware Bay: A submerging marginal marine sedimentary basin

USGS Publications Warehouse

Fletcher, C. H.; Knebel, H.J.; Kraft, J.C.

1992-01-01

The Holocene transgression of the Delaware Bay estuary and adjacent Atlantic coast results from the combined effect of regional crustal subsidence and eustasy. Together, the estuary and ocean coast constitute a small sedimentary basin whose principal depocenter has migrated with the transgression. A millenial time series of isopach and paleogeographic reconstructions for the migrating depocenter outlines the basin-wide pattern of sediment distribution and accumulation. Upland sediments entering the basin through the estuarine turbidity maximum accumulate in tidal wetland or open water sedimentary environments. Wind-wave activity at the edge of the tidal wetlands erodes the aggraded Holocene section and builds migrating washover barriers. Along the Atlantic and estuary coasts of Delaware, the area of the upland environment decreases from 2.0 billion m2 to 730 million m2 during the transgression. The area of the tidal wetland environment increases from 140 million to 270 million m2, and due to the widening of the estuary the area of open water increases from 190 million to 1.21 billion m2. Gross uncorrected rates of sediment accumulation for the tidal wetlands decrease from 0.64 mm/yr at 6 ka to 0.48 mm/yr at 1 ka. In the open water environments uncorrected rates decrease from 0.50 mm/yr to 0.04 mm/yr over the same period. We also present data on total sediment volumes within the tidal wetland and open water environments at specific intervals during the Holocene. 

Petroleum geology of the major producing basins of Algeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Attar, A.; Chaouch, A.

1988-08-01

The South Atlas flexure divides Algeria into two contrasting geologic provinces: (1) the Saharan Atlas and offshore region in the north, both of which are part of the Mediterranean basin, and (2) the Saharan platform on the south, part of the North African craton. The limits of the various sedimentary basins on the Saharan platform are tied to late Paleozoic (Hercynian) crustal reactivation. Comparable structurally controlled basins in northern Algeria are the products of Mesozoic-Recent tectonism. The spatial and temporal distribution of hydrocarbons in the Algerian Sahara can be understood in terms of the geologic evolution of the region. Analysismore » of areas of proven hydrocarbon reserves permits the following generalizations. (1) There is a concentration of oil and gas fields northeast of a northwest-southeast-trending line connecting Hassi R'Mel with In Amenas. Production is also established in the Sbaa basin and in northern Algeria, where recent discoveries have been made in, respectively, upper Paleozoic and Mesozoic reservoirs. (2) Hydrocarbon are present throughout the entire sedimentary column, but major production currently is restricted to the lower Paleozoic (Cambrian-Ordovician and Lower Devonian) and Triassic reservoirs.« less

Hydrogeologic framework of fractured sedimentary rock, Newark Basin, New Jersey

USGS Publications Warehouse

Lacombe, Pierre J.; Burton, William C.

2010-01-01

The hydrogeologic framework of fractured sedimentary bedrock at the former Naval Air Warfare Center (NAWC), Trenton, New Jersey, a trichloroethylene (TCE)-contaminated site in the Newark Basin, is developed using an understanding of the geologic history of the strata, gamma-ray logs, and rock cores. NAWC is the newest field research site established as part of the U.S. Geological Survey Toxic Substances Hydrology Program, Department of Defense (DoD) Strategic Environmental Research and Development Program, and DoD Environmental Security Technology Certification Program to investigate contaminant remediation in fractured rock. Sedimentary bedrock at the NAWC research site comprises the Skunk Hollow, Byram, and Ewing Creek Members of the Lockatong Formation and Raven Rock Member of the Stockton Formation. Muds of the Lockatong Formation that were deposited in Van Houten cycles during the Triassic have lithified to form the bedrock that is typical of much of the Newark Basin. Four lithotypes formed from the sediments include black, carbon-rich laminated mudstone, dark-gray laminated mudstone, light-gray massive mudstone, and red massive mudstone. Diagenesis, tectonic compression, off-loading, and weathering have altered the rocks to give some strata greater hydraulic conductivity than other strata. Each stratum in the Lockatong Formation is 0.3 to 8 m thick, strikes N65 degrees E, and dips 25 degrees to 70 degrees NW. The black, carbon-rich laminated mudstone tends to fracture easily, has a relatively high hydraulic conductivity and is associated with high natural gamma-ray count rates. The dark-gray laminated mudstone is less fractured and has a lower hydraulic conductivity than the black carbon-rich laminated mudstone. The light-gray and the red massive mudstones are highly indurated and tend to have the least fractures and a low hydraulic conductivity. The differences in gamma-ray count rates for different mudstones allow gamma-ray logs to be used to correlate and delineate the lithostratigraphy from multiple wells. Gamma-ray logs and rock cores were correlated to develop a 13-layer gamma-ray stratigraphy and 41-layer lithostratigraphy throughout the fractured sedimentary rock research site. Detailed hydrogeologic framework shows that black carbon-rich laminated mudstones are the most hydraulically conductive. Water-quality and aquifer-test data indicate that groundwater flow is greatest and TCE contamination is highest in the black, carbon- and clay-rich laminated mudstones. Large-scale groundwater flow at the NAWC research site can be modeled as highly anisotropic with the highest component of permeability occurring along bedding planes.

The role of the thermal convection of fluids in the formation of unconformity-type uranium deposits: the Athabasca Basin, Canada

NASA Astrophysics Data System (ADS)

Pek, A. A.; Malkovsky, V. I.

2017-05-01

In the global production of uranium, 18% belong to the unconformity-type Canadian deposits localized in the Athabasca Basin. These deposits, which are unique in terms of their ore quality, were primarily studied by Canadian and French scientists. They have elaborated the diagenetic-hydrothermal hypothesis of ore formation, which suggests that (1) the deposits were formed within a sedimentary basin near an unconformity surface dividing the folded Archean-Proterozoic metamorphic basement and a gently dipping sedimentary cover, which is not affected by metamorphism; (2) the spatial accommodation of the deposits is controlled by the rejuvenated faults in the basement at their exit into the overlying sedimentary sequence; the ore bodies are localized above and below the unconformity surface; (3) the occurrence of graphite-bearing rocks is an important factor in controlling the local structural mineralization; (4) the ore bodies are the products of uranium precipitation on a reducing barrier. The mechanism that drives the circulation of ore-forming hydrothermal solutions has remained one of the main unclear questions in the general genetic concept. The ore was deposited above the surface of the unconformity due to the upflow discharge of the solution from the fault zones into the overlying conglomerate and sandstone. The ore formation below this surface is a result of the downflow migration of the solutions along the fault zones from sandstone into the basement rocks. A thermal convective system with the conjugated convection cells in the basement and sedimentary fill of the basin may be a possible explanation of why the hydrotherms circulate in the opposite directions. The results of our computations in the model setting of the free thermal convection of fluids are consistent with the conceptual reasoning about the conditions of the formation of unique uranium deposits in the Athabasca Basin. The calculated rates of the focused solution circulation through the fault zones in the upflow and downflow branches of a convection cell allow us to evaluate the time of ore formation up to the first hundreds of thousands years.

Re-Os geochronology of a Mesoproterozoic sedimentary succession, Taoudeni basin, Mauritania: Implications for basin-wide correlations and Re-Os organic-rich sediments systematics

NASA Astrophysics Data System (ADS)

Rooney, Alan D.; Selby, David; Houzay, Jean-Pierre; Renne, Paul R.

2010-01-01

The exceptionally well-preserved sedimentary rocks of the Taoudeni basin, NW Africa represent one of the world's most widespread (> 1 M km 2) Proterozoic successions. Hitherto, the sedimentary rocks were considered to be Mid Tonian based on Rb-Sr illite and glauconite geochronology of the Atar Group. However, new Re-Os organic-rich sediment (ORS) geochronology from two drill cores indicates that the Proterozoic Atar Group is ˜ 200 Ma older (1107 ± 12 Ma, 1109 ± 22 Ma and 1105 ± 37 Ma). The Re-Os geochronology suggests that the Rb-Sr geochronology records the age of diagenetic events possibly associated with the Pan African collision. The new Re-Os geochronology data provide absolute age constraints for recent carbon isotope chemostratigraphy which suggests that the Atar Group is Mesoproterozoic and not Neoproterozoic. The new Re-Os ORS geochronology supports previous studies that suggest that rapid hydrocarbon generation (flash pyrolysis) from contact metamorphism of a dolerite sill does not significantly disturb the Re-Os ORS systematics. Modelled contact conditions suggest that the Re-Os ORS systematics remain undisturbed at ˜ 650 °C at the sill/shale contact and ≥ 280 °C 20 m from the sill/shale contact. Moreover, the Re-Os geochronology indicates that the West African craton has a depositional history that predates 1100 Ma and that ORS can be correlated on a basin-wide scale. In addition, the Re-Os depositional ages for the ORS of the Taoudeni basin are comparable to those of ORS from the São Francisco craton, suggesting that these cratons are correlatable. This postulate is further supported by identical Os i values for the Atar Group and the Vazante Group of the São Francisco craton.

Site response and attenuation in the Puget Lowland, Washington State

USGS Publications Warehouse

Pratt, T.L.; Brocher, T.M.

2006-01-01

Simple spectral ratio (SSR) and horizontal-to-vertical (HN) site-response estimates at 47 sites in the Puget Lowland of Washington State document significant attenuation of 1.5- to 20-Hz shear waves within sedimentary basins there. Amplitudes of the horizontal components of shear-wave arrivals from three local earthquakes were used to compute SSRs with respect to the average of two bedrock sites and H/V spectral ratios with respect to the vertical component of the shear-wave arrivals at each site. SSR site-response curves at thick basin sites show peak amplifications of 2 to 6 at frequencies of 3 to 6 Hz, and decreasing spectra amplification with increasing frequency above 6 Hz. SSRs at nonbasin sites show a variety of shapes and larger resonance peaks. We attribute the spectral decay at frequencies above the amplification peak at basin sites to attenuation within the basin strata. Computing the frequency-independent, depth-dependent attenuation factor (Qs,int) from the SSR spectral decay between 2 and 20 Hz gives values of 5 to 40 for shallow sedimentary deposits and about 250 for the deepest sedimentary strata (7 km depth). H/V site responses show less spectral decay than the SSR responses but contain many of the same resonance peaks. We hypothesize that the H/V method yields a flatter response across the frequency spectrum than SSRs because the H/V reference signal (vertical component of the shear-wave arrivals) has undergone a degree of attenuation similar to the horizontal component recordings. Correcting the SSR site responses for attenuation within the basins by removing the spectral decay improves agreement between SSR and H/V estimates.

Volcano-sedimentary characteristics in the Abu Treifiya Basin, Cairo-Suez District, Egypt: Example of dynamics and fluidization over sedimentary and volcaniclastic beds by emplacement of syn-volcanic basaltic rocks

NASA Astrophysics Data System (ADS)

Khalaf, E. A.; Abdel Motelib, A.; Hammed, M. S.; El Manawi, A. H.

2015-12-01

This paper describes the Neogene lava-sediment mingling from the Abu Treifiya Basin, Cairo-Suez district, Egypt. The lava-sediment interactions as peperites have been identified for the first time at the study area and can be used as paleoenvironmental indicators. The identification of peperite reflects contemporaneous time relationship between volcanism and sedimentation and this finding is of primary importance to address the evolutional reconstruction of the Abu Treifiya Basin. Characterization of the facies architecture and textural framework of peperites was carried out through detailed description and interpretation of their outcrops. The peperites and sedimentary rocks are up to 350 m thick and form a distinct stratigraphic framework of diverse lithology that is widespread over several kilometers at the study area. Lateral and vertical facies of the peperites vary from sediment intercalated with the extrusive/intrusive basaltic rocks forming peperitic breccias to lava-sediment contacts at a large to small scales, respectively. Peperites encompass five main facies types ascribed to: (i) carbonate sediments-hosted fluidal and blocky peperites, (ii) lava flow-hosted blocky peperites, (iii) volcaniclastics-hosted fluidal and blocky peperites, (iv) sandstone/siltstone rocks-hosted blocky peperites, and (iv) debris-flows-hosted blocky peperites. Soft sediment deformation structures, vesiculated sediments, sediments filled-vesicles, and fractures in lava flows indicate that lava flows mingled with unconsolidated wet sediments. All the peperites in this study could be described as blocky or fluidal, but mixtures of different clast shapes occur regardless of the host sediment. The presence of fluidal and blocky juvenile clasts elucidates different eruptive styles, reflecting a ductile and brittle fragmentation. The gradual variation from fluidal to blocky peperite texture, producing the vertical grading is affected by influencing factors, e.g., the viscosity, magma temperature, confining pressure, sediment fluidization, and vapor film at the magma-sediment interactions. Peperites in the study area record deposition within a shallow marine and fluvio-lacustrine environment accumulated in a rift-related basin developed during pre- to syn-rift phase, respectively. The facies transitions (peperites) in this area resulted from the explosive and sediment depositional processes, which were mingled separately by volcanism under contrast geological conditions. The development of such contrast in the depositional sequences reflects variation in the accommodation to sediment supply in the same accumulation space inside the depocenters during the rifting of the Abu Treifiya Basin. Hydrothermal mineralizations comprising quartz and carbonate are restricted to peperites and lava flows.

The origin of brines and salts in Chilean salars: a hydrochemical review

NASA Astrophysics Data System (ADS)

Risacher, François; Alonso, Hugo; Salazar, Carlos

2003-11-01

Northern Chile is characterized by a succession of north-south-trending ranges and basins occupied by numerous saline lakes and salt crusts, collectively called salars. Fossil salt crusts are found to the west in the extremely arid Central Valley, while active salars receiving permanent inflows fill many intravolcanic basins to the east in the semiarid Cordillera. Sea salts and desert dust are blown eastward over the Cordillera, where they constitute an appreciable fraction of the solute load of very dilute waters (salt content<0.1 g/l). The weathering of volcanic rocks contributes most components to inflow waters with salt content ranging from 0.1 to 0.6 g/l. However, the average salt content of all inflows is much higher: about 3.2 g/l. Chemical composition, Cl/Br ratio, and 18O- 2H isotope contents point to the mixing of very dilute meteoric waters with present lake brines for the origin of saline inflows. Ancient gypsum in deep sedimentary formations seems to be the only evaporitic mineral recycled in present salars. Saline lakes and subsurface brines are under steady-state regime. The average residence time of conservative components ranges from a few years to some thousands years, which indicates a permanent leakage of the brines through bottom sediments. The infiltrating brines are recycled in the hydrologic system where they mix with dilute meteoric waters. High heat flow is the likely driving force that moves the deep waters in this magmatic arc region. Active Chilean salars cannot be considered as terminal lakes nor, strictly speaking, as closed basin lakes. Almost all incoming salts leave the basin and are transported elsewhere. Moreover, the dissolution of fossil salt crusts in some active salars also carries away important fluxes of components in percolating brines. Evaporative concentration of inflow waters leads to sulfate-rich or calcium-rich, near-neutral brines. Alkaline brines are almost completely lacking. The alkalinity/calcium ratio of inflow waters is lowered by the oxidation of native sulfur (reducing alkalinity) and the deposition of eolian gypsum (increasing Ca concentration). Theoretically, SO 4-rich inflow waters and their derived SO 4-rich brines should be found in the intravolcanic basins of the Cordillera because of the ubiquity of native sulfur, while Ca-rich brines should prevail in sedimentary basins where Ca-rich minerals are abundant. This relation is perfectly observed in the salar de Atacama, the largest in Chile. However, several salars located within the volcanic Cordillera belong to the Ca-rich group. Inflows and brines may have acquired their Ca-rich composition in Pleistocene time when their drainage basins were mainly sedimentary. Later on, recent lava flows and ignimbrites covered the sedimentary formations. Underground waters may have kept their early sedimentary signature by continuous recycling. However, the weathering of volcanic rocks tend to slowly shift the water compositions from the Ca-rich to the SO 4-rich type.

Radiogenic heat production in sedimentary rocks of the Gulf of Mexico Basin, south Texas

USGS Publications Warehouse

McKenna, T.E.; Sharp, J.M.

1998-01-01

Radiogenic heat production within the sedimentary section of the Gulf of Mexico basin is a significant source of heat. Radiogenic heat should be included in thermal models of this basin (and perhaps other sedimentary basins). We calculate that radiogenic heat may contribute up to 26% of the overall surface heat-flow density for an area in south Texas. Based on measurements of the radioactive decay rate of ??-particles, potassium concentration, and bulk density, we calculate radiogenic heat production for Stuart City (Lower Cretaceous) limestones, Wilcox (Eocene) sandstones and mudrocks, and Frio (Oligocene) sandstones and mudrocks from south Texas. Heat production rates range from a low of 0.07 ?? 0.01 ??W/m3 in clean Stuart City limestones to 2.21 ?? 0.24??W/m3 in Frio mudrocks. Mean heat production rates for Wilcox sandstones, Frio sandstones, Wilcox mudrocks, and Frio mudrocks are 0.88, 1.19, 1.50, and 1.72 ??W/m3, respectively. In general, the mudrocks produce about 30-40% more heat than stratigraphically equivalent sandstones. Frio rocks produce about 15% more heat than Wilcox rocks per unit volume of clastic rock (sandstone/mudrock). A one-dimensional heat-conduction model indicates that this radiogenic heat source has a significant effect on subsurface temperatures. If a thermal model were calibrated to observed temperatures by optimizing basal heat-flow density and ignoring sediment heat production, the extrapolated present-day temperature of a deeply buried source rock would be overestimated.Radiogenic heat production within the sedimentary section of the Gulf of Mexico basin is a significant source of heat. Radiogenic heat should be included in thermal models of this basin (and perhaps other sedimentary basins). We calculate that radiogenic heat may contribute up to 26% of the overall surface heat-flow density for an area in south Texas. Based on measurements of the radioactive decay rate of ??-particles, potassium concentration, and bulk density, we calculate radiogenic heat production for Stuart City (Lower Cretaceous) limestones, Wilcox (Eocene) sandstones and mudrocks, and Frio (Oligocene) sandstones and mudrocks from south Texas. Heat production rates range from a low of 0.07??0.01 ??W/m3 in clean Stuart City limestones to 2.21??0.24 ??W/m3 in Frio mudrocks. Mean heat production rates for Wilcox sandstones, Frio sandstones, Wilcox mudrocks, and Frio mudrocks are 0.88, 1.19, 1.50, and 1.72 ??W/m3, respectively. In general, the mudrocks produce about 30-40% more heat than stratigraphically equivalent sandstones. Frio rocks produce about 15% more heat than Wilcox rocks per unit volume of clastic rock (sandstone/mudrock). A one-dimensional heat-conduction model indicates that this radiogenic heat source has a significant effect on subsurface temperatures. If a thermal model were calibrated to observed temperatures by optimizing basal heat-flow density and ignoring sediment heat production, the extrapolated present-day temperature of a deeply buried source rock would be overestimated.

Summary of 2012 reconnaissance field studies related to the petroleum geology of the Nenana Basin, interior Alaska

USGS Publications Warehouse

Wartes, Marwan A.; Gillis, Robert J.; Herriott, Trystan M.; Stanley, Richard G.; Helmold, Kenneth P.; Peterson, C. Shaun; Benowitz, Jeffrey A.

2013-01-01

The Alaska Division of Geological & Geophysical Surveys (DGGS) recently initiated a multi-year review of the hydrocarbon potential of frontier sedimentary basins in Alaska (Swenson and others, 2012). In collaboration with the Alaska Division of Oil & Gas and the U.S. Geological Survey we conducted reconnaissance field studies in two basins with recognized natural gas potential—the Susitna basin and the Nenana basin (LePain and others, 2012). This paper summarizes our initial work on the Nenana basin; a brief summary of our work in the Susitna basin can be found in Gillis and others (in press). During early May 2012, we conducted ten days of helicopter-supported fieldwork and reconnaissance sampling along the northern Alaska Range foothills and Yukon–Tanana upland near Fairbanks (fig. 1). The goal of this work was to improve our understanding of the geologic development of the Nenana basin and to collect a suite of samples to better evaluate hydrocarbon potential. Most laboratory analyses have not yet been completed, so this preliminary report serves as a summary of field data and sets the framework for future, more comprehensive analysis to be presented in later publications.

The Indosinian orogeny: A perspective from sedimentary archives of north Vietnam

NASA Astrophysics Data System (ADS)

Rossignol, Camille; Bourquin, Sylvie; Hallot, Erwan; Poujol, Marc; Dabard, Marie-Pierre; Martini, Rossana; Villeneuve, Michel; Cornée, Jean-Jacques; Brayard, Arnaud; Roger, Françoise

2018-06-01

The Triassic stratigraphic framework for the Song Da and the Sam Nua basins, north Vietnam, suffers important discrepancies regarding both the depositional environments and ages of the main formations they contain. Using sedimentological analyses and dating (foraminifer biostratigraphy and U-Pb dating on detrital zircon), we provide an improved stratigraphic framework for both basins. A striking feature in the Song Da Basin, located on the southern margin of the South China Block, is the diachronous deposition, over a basal unconformity, of terrestrial and marine deposits. The sedimentary succession of the Song Da Basin points to a foreland setting during the late Early to the Middle Triassic, which contrasts with the commonly interpreted rift setting. On the northern margin of the Indochina Block, the Sam Nua basin recorded the activity of a proximal magmatic arc during the late Permian up to the Anisian. This arc resulted from the subduction of a southward dipping oceanic slab that separated the South China block from the Indochina block. During the Middle to the Late Triassic, the Song Da and Sam Nua basins underwent erosion that led to the formation of a major unconformity, resulting from the erosion of the Middle Triassic Indosinian mountain belt, built after an ongoing continental collision between the South China and the Indochina blocks. Later, during the Late Triassic, as syn- to post-orogenic foreland basins in a terrestrial setting, the Song Da and Sam Nua basins experienced the deposition of very coarse detrital material representing products of the mountain belt erosion.

High resolution evolution of post-rift terrigenous sediment yields in the Provence Basin (Western Mediterranean): relation with climate and tectonics

NASA Astrophysics Data System (ADS)

Leroux, Estelle; Rabineau, Marina; Aslanian, Daniel; Gorini, Christian; Molliex, Stéphane; Bache, François; Robin, Cécile; Droz, Laurence; Moulin, Maryline; Poort, Jeffrey; Rubino, Jean-Loup; Suc, Jean-Pierre

2017-04-01

The correlation of stratigraphic markers between the shelf, the slope and the deep basin have enabled us to provide a complete and quantitative view of sediments fluxes for the last 6 Ma on the entire Gulf of Lions margin. Messinian units and Pliocene and Pleistocene chronostratigraphic markers have been correlated from the shelf to the deep basin and the total sediment thickness from the basement (20 Ma) to the present-day seafloor has also been mapped. After Time/Depth conversion and decompaction of each stratigraphic interval, sedimentary volumes were calculated. Sediment flux evolution shows that a dramatic terrigenous peak occurred during the Messinian Salinity Crisis. The Pliocene-Pleistocene average flux appears to have been three times higher than that of the Miocene, which seems in agreement with published measurements from the World's ocean. This study also highlights the Mid-Pleistocene Revolution around 0.9 Ma, which resulted in an almost doubling of sedimentary detrital fluxes in the Provencal Basin. These results are discussed in relation with world-wide climate and alpine tectonics.

Tectonic controls on the hydrocarbon habitats of the Barito, Kutei, and Tarakan Basins, Eastern Kalimantan, Indonesia: major dissimilarities in adjoining basins

NASA Astrophysics Data System (ADS)

Satyana, Awang Harun; Nugroho, Djoko; Surantoko, Imanhardjo

1999-04-01

The Barito, Kutei, and Tarakan Basins are located in the eastern half of Kalimantan (Borneo) Island, Indonesia. The basins are distinguished by their different tectonic styles during Tertiary and Pleistocene times. In the Barito Basin, the deformation is a consequence of two distinct, separate, regimes. Firstly, an initial transtensional regime during which sinistral shear resulted in the formation of a series of wrench-related rifts, and secondly, a subsequent transpressional regime involving convergent uplift, reactivating old structures and resulting in wrenching, reverse faulting and folding within the basin. Presently, NNE-SSW and E-W trending structures are concentrated in the northeastern and northern parts of the basin, respectively. In the northeastern part, the structures become increasingly imbricated towards the Meratus Mountains and involve the basement. The western and southern parts of the Barito Basin are only weakly deformed. In the Kutei Basin, the present day dominant structural trend is a series of tightly folded, NNE-SSW trending anticlines and synclines forming the Samarinda Anticlinorium which is dominant in the eastern part of the basin. Deformation is less intense offshore. Middle Miocene to Recent structural growth is suggested by depositional thinning over the structures. The western basin area is uplifted, large structures are evident in several places. The origin of the Kutei structures is still in question and proposed mechanisms include vertical diapirism, gravitational gliding, inversion through regional wrenching, detachment folds over inverted structures, and inverted delta growth-fault system. In the Tarakan Basin, the present structural grain is typified by NNE-SSW normal faults which are mostly developed in the marginal and offshore areas. These structures formed on older NW-SE trending folds and are normal to the direction of the basin sedimentary thickening suggesting that they developed contemporaneously with deposition, as growth-faults, and may be the direct result of sedimentary loading by successive deltaic deposits. Older structures were formed in the onshore basin, characterized by the N-S trending folds resulting from the collision of the Central Range terranes to the west of the basin. Hydrocarbon accumulations in the three basins are strongly controlled by their tectonic styles. In the Barito Basin, all fields are located in west-verging faulted anticlines. The history of tectonic inversion and convergent uplift of the Meratus Mountains, isostatically, have caused the generation, migration, and trapping of hydrocarbons. In the Kutei Basin, the onshore Samarinda Anticlinorium and the offshore Mahakam Foldbelt are prolific petroleum provinces, within which most Indonesian giant fields are located. In the offshore, very gentle folds also play a role as hydrocarbon traps, in association with stratigraphic entrapment. These structures have recently become primary targets for exploratory drilling. In the Tarakan Basin, the prominent NW-SE anticlines, fragmented by NE-SW growth-faults, have proved to be petroleum traps. The main producing pools are located in the downthrown blocks of the faults. Diverse tectonic styles within the producing basins of Kalimantan compel separate exploration approaches to each basin. To discover new opportunities in exploration, it is important to understand the structural evolution of neighbouring basins.

Genesis of the largest Amazonian wetland in northern Brazil inferred by morphology and gravity anomalies

NASA Astrophysics Data System (ADS)

Rossetti, Dilce de Fátima; Cassola Molina, Eder; Cremon, Édipo Henrique

2016-08-01

The Pantanal Setentrional (PS) is the second largest wetland in Brazil, occurring in a region of northern Amazonia previously regarded as part of the intracratonic Solimões Basin. However, while Paleozoic to Neogene strata are recorded in this basin, the PS constitutes a broad region with an expressive record of only Late Pleistocene and Holocene deposits. The hypothesis investigated in the present work is if these younger deposits were formed within a sedimentary basin having a geological history separated from the Solimões Basin. Due to the location in a remote region of low accessibility, the sedimentary fill of the PS wetland remains largely unknown in subsurface. In the present work, we combine geomorphological and gravity data acquired on a global basis by several satellite gravity missions to approach the geological context of this region. The results revealed a wetland characterized in surface by a low-lying terrain with wedge shape and concave-up geometry that is in sharp contact with highland areas of Precambrian rocks of the Guiana Shield. Such contact is defined by a series of mainly NE- or NW-trending straight lineaments that eventually extend into both the Guiana Shield and the PS wetland. Also of relevance is that a great part of the PS wetland sedimentary cover consists of dominantly sandy deposits preserved as residual paleo-landforms with triangular shapes previously related to megafan depositional systems. These are distributed radially at the northern margin of the PS, with axis toward basement rocks and fringes toward the wetland's center, the latter containing the largest megafan landform. The analysis of gravity anomaly data revealed a main NNE-trending chain ∼500 km in length defined by high gravity values (i.e., up to 60 mGal); these are bounded by negative anomalies as low as -90 mGal. The chain with positive gravity anomaly marks the center of a subsiding area having a geological evolution that differs from the adjacent intracratonic Solimões Basin. Deep rifting associated with the rise of high-density material from the mantle in replacement of low-density continental crust is hypothesized as the most likely load-driving mechanism responsible for the subsidence of the PS sedimentary basin. Alternatively, this might be a shallow basin formed during the Late Quaternary due to mild subsidence of a high-density basement. This process would have been caused by tectonic reactivations of NE-trending strike-slip faults along a zone of low elastic thickness of the lithosphere that characterizes this region of South American platform.

3.5-D model of sediment age and grain size for the Northern Gulf of Aqaba-Elat (Red Sea) using submarine cores

NASA Astrophysics Data System (ADS)

Kanari, Mor; Ben-Avraham, Zvi; Tibor, Gideon; Goodman Tchernov, Beverly N.; Bookman, Revital; Taha, Nimer; Marco, Shmuel

2016-04-01

The Northern Gulf of Aqaba-Elat (NGAE) is the northeast extension of the Red Sea, located at the southernmost part of the Dead Sea Fault, at the transition zone between the deep en-echelon submarine basins of the Red Sea and the shallow continental basins of the Arava Valley (Israel and Jordan). We aim to characterize the top sedimentary cover across the NGAE in order to check the effect of tectonics on the sedimentary column, using high resolution grain size data and radiocarbon dating of core sediments. We analyzed 11 piston cores and 9 short cores: high resolution grain-size and radiocarbon age determinations were used to compile a 3.5-D (3.5 dimensional) model of age-depth-grain size for the top 3-5 meters of the NGAE. Two general trends of the grain size spatial distribution are observed: grains are coarsest at the NE corner of the NGAE (Aqaba coastline) and grow finer with the distance to the west on the shelf and with the distance from shore to the south. Long- and short-term accumulation rates were compiled for the entire NGAE, demonstrating a distinct E-W trend on the shelf and a NNE-SSW trend in the deep basin. The 3.5-D age-depth-grain size model conforms to- and validates the tectonic structure of the shelf detailed by previous authors. We suggest that the impact of tectonic structure of the shelf is highly significant in terms of spatial variations across the shelf, both in age of the sediment and its grain size characteristics. The temporal-spatial distribution of the grain size in the deep basin of the NGAE reveals a correlation between sediment age, dominant grain size and active tectonics: fine-grain, old sediment in the margins (Late Pleistocene, as old as >40 ka on the west margin; Early Holocene, as old as 7.5 ka, on the east margin), and Late Pleistocene sediment farther south from the dominant active diagonal fault which underlies the Elat Canyon. Young coarse sediment is present in the middle of the basin, where most of the active sediment transportation (and tectonic activity) take place. The dominant sedimentary activity follows the migration of the active tectonic fault segments from east to west between 40 ka to present. We observe focusing of turbidites to the location of the dominant active tectonic fault. A spatial/temporal evolutionary model is presented for the sedimentary processes of the NGAE since 40 ka to present, suggesting three phases of development: (a) Late Pleistocene 40 to 12 ka; (b) Early to Mid-Holocene 12 to 5-4 ka; (c) Late Holocene 5-4 ka to present.

Core evidence of paleoseismic events in Paleogene deposits of the Shulu Sag in the Bohai Bay Basin, east China, and their petroleum geologic significance

NASA Astrophysics Data System (ADS)

Zheng, Lijing; Jiang, Zaixing; Liu, Hui; Kong, Xiangxin; Li, Haipeng; Jiang, Xiaolong

2015-10-01

The Shulu Sag, located in the southwestern corner of the Jizhong Depression, Bohai Bay Basin of east China, is a NE-SW trending, elongate Cenozoic half-graben basin. The lowermost part of the third member of the Shahejie Formation in this basin is characterized by continental rudstone and calcilutite to calcisiltite facies. Based on core observation and regional geologic analysis, seismites are recognized in these lacustrine deposits, which include soft-sediment deformation structures (sedimentary dikes, hydraulic shattering, diapir structures, convolute lamination, load-flame structures, ball-and-pillow structures, loop bedding, and subsidence structures), synsedimentary faults, and seismoturbidites. In addition, mixed-source rudstones, consisting of the Paleozoic carbonate clasts and in situ calcilutite clasts in the lowermost submember of Shahejie 3, appear in the seismites, suggesting an earthquake origin. A complete representative vertical sequence in the lowermost part of the third member found in well ST1H located in the central part of the Shulu Sag shows, from the base to the top: underlying undeformed layers, synsedimentary faults, liquefied carbonate rocks, allogenetic seismoturbidites, and overlying undeformed layers. Seismites are widely distributed around this well and there are multiple sets of stacked seismites separated by undeformed sediment. The nearby NW-trending Taijiazhuang fault whose fault growth index is from 1.1 to 1.8 and the NNE-trending Xinhe fault with a fault growth index of 1.3-1.9 may be the source of the instability to create the seismites. These deformed sedimentary layers are favorable for the accumulation of oil and gas; for example, sedimentary dikes can cut through many layers and serve as conduits for fluid migration. Sedimentary faults and fractures induced by earthquakes can act as oil and gas migration channels or store petroleum products as well. Seismoturbidites and mixed-source rudstones are excellent reservoirs due to their abundant primary or dissolved pores.

Do river channels decrease in width downstream on Distributive Fluvial Systems? An evaluation of modern mega-fans

NASA Astrophysics Data System (ADS)

Espinoza, T. N.; Scuderi, L. A.; Weissmann, G. S.; Hartley, A. J.

2014-12-01

Recent studies on aggradational continental sedimentary basins globally show that fluvial deposits in most modern sedimentary basins are dominated Distributive Fluvial Systems (DFS). DFS's are identified by: (1) pattern of channels and floodplain deposits that radiate outward from an apex located where the river enters the sedimentary basin, (2) deposition where an alluvial system becomes unconfined upon entering the sedimentary basin, (3) broadly fan shaped deposit that is convex upward across the DFS and concave upward down-fan, and (4) if the DFS is incised, an intersection point above which the alluvial system is held in an incised valley and below which it distributes sediment across an active depositional lobe. Several papers about DFS hypothesized that rivers on DFS decrease in size down-fan. We are testing this hypothesis through evaluation of LANDSAT and STRM data from large DFS described by Hartley et al (2010). We use ArcGIS to: (1) open the images and merge them together if there are more than one image corresponding to the DFS being studied, (2) use a Maximum Likelihood Analysis in six classes to segment different features on the DFS (e.g. exposed sands, water, vegetation, and other fan environments), (3) isolate the classes that correspond to the active channel belt (e.g., exposed sand bars and water), (4) divide the active channel belt into 1000 m long sections, (5) determine the area of active channel belt in each section, and (6) calculate the average width of the river in each section (e.g., W = area/1000m). We present our result for each DFS river on a graph that shows the change in width downstream. Our final product will be a dataset that contains width versus distance down-fan from the apex for as many of the large DFS from Hartley et al (2010) as possible. If the hypothesis is supported, the decrease in width could have a substantial predictive significance on sandstone geometry in fluvial successions.

2 - 4 million years of sedimentary processes in the Labrador Sea: implication for North Atlantic stratigraphy

NASA Astrophysics Data System (ADS)

Mosher, D. C.; Saint-Ange, F.; Campbell, C.; Piper, D. J.

2012-12-01

Marine sedimentary records from the western North Atlantic show that a significant portion of sediment deposited since the Pliocene originated from the Canadian Shield. In the Labrador Sea, previous studies have shown that bottom currents .strongly influenced sedimentation during the Pliocene, while during the Quaternary, intensification of turbidity current flows related to meltwater events were a dominant factor in supplying sediment to the basin and in the development of the North Atlantic Mid-Ocean Channel (NAMOC). Despite understanding this general pattern of sediment flux, details regarding the transfer of sediment from the Labrador Shelf to deep water and from the Labrador Sea to the North Atlantic remain poorly understood. Our study focuses on sedimentary processes occurring along the Labrador margin since the Pliocene and their consequences on the margin architecture, connection to the NAMOC, and role in sediment flux from the Labrador basin to the Sohm Abyssal Plain. Piston core and high resolution seismic data reveal that during the Pliocene to mid Pleistocene, widespread slope failures led to mass transport deposition along the entire Labrador continental slope. After the mid Pleistocene, sedimentation along the margin was dominated by the combined effects of glaciation and active bottom currents. On the shelf, prograded sedimentary wedges filled troughs and agraded till sheets form intervening banks. On the slope, stacked glaciogenic fans developed seaward of transverse troughs between 400 and 2800 mbsl. On the lower slope, seismic data show thick sediment drifts capped by glacio-marine mud. This unit is draped by well stratified sediment and marks a switch from a contourite dominated regime to a turbidite dominated regime. This shift occurred around 0.5 - 0.8 ka and correlates to the intensification of glaciations. Late Pleistocene sediments on the upper slope consist of stratified sediments related to proglacial plume fall-out. Coarse grained sediments, other than ice rafted detritus, by-passed the upper and middle slope and were transported to the lower slope and deep ocean. Seismic profiles and multibeam data along the Labrador Slope show a complex network of channels, with wide flat-bottomed channels off Saglek Bank to narrow channels off Cartwright Bank. The channels merge around 3000 mbsl to form single wide (~20 km) channels that eventually intersect, or flow parallel to the NAMOC. Rapid development of the NAMOC from the mid to late Pleistocene affected depositional patterns for sediment sourced from the Labrador margin. Downslope-transported sediment from the Labrador margin mostly tends to fill the basin or feed into NAMOC through tributary systems, whereas sediments derived from Hudson Strait feed the NAMOC and eventually the Sohm Abyssal plain. Sediment transported southward by the Western Boundary Undercurrent and Labrador Current likely reflect input along the margin, from Hudson Strait to Orphan Basin. Turbidite spill-over deposits are observed onlapping the continental margin of Labrador and Newfoundland as far south as Newfoundland Ridge.

Low-Temperature Hydrothermal Resource Potential Estimate

DOE Data Explorer

Katherine Young

2016-06-30

Compilation of data (spreadsheet and shapefiles) for several low-temperature resource types, including isolated springs and wells, delineated area convection systems, sedimentary basins and coastal plains sedimentary systems. For each system, we include estimates of the accessible resource base, mean extractable resource and beneficial heat. Data compiled from USGS and other sources. The paper (submitted to GRC 2016) describing the methodology and analysis is also included.

Estimates of chemical compaction and maximum burial depth from bedding parallel stylolites

NASA Astrophysics Data System (ADS)

Gasparrini, Marta; Beaudoin, Nicolas; Lacombe, Olivier; David, Marie-Eleonore; Youssef, Souhail; Koehn, Daniel

2017-04-01

Chemical compaction is a diagenetic process affecting sedimentary series during burial that develops rough dissolution surfaces named Bedding Parallel Stylolites (BPS). BPS are related to the dissolution of important rock volumes and can lead to porosity reduction around them due to post-dissolution cementation. Our understanding of the effect of chemical compaction on rock volume and porosity evolution during basin burial is however too tight yet to be fully taken into account in basin models and thermal or fluid-flow simulations. This contribution presents a novel and multidisciplinary approach to quantify chemical compaction and to estimate maximum paleodepth of burial, applied to the Dogger carbonate reservoirs from the Paris Basin sub-surface. This succession experienced a relatively simple burial history (nearly continuous burial from Upper Jurassic to Upper Cretaceous, followed by a main uplift phase), and mainly underwent normal overburden (inducing development of BPS), escaping major tectonic stress episodes. We considered one core from the depocentre and one from the eastern margin of the basin in the same stratigraphic interval (Bathonian Sup. - Callovian Inf.; restricted lagoonal setting), and analysed the macro- and micro-facies to distinguish five main depositional environments. Type and abundance of BPS were continuously recorded along the logs and treated statistically to obtain preliminary rules relying the occurrence of the BPS as a function of the contrasting facies and burial histories. The treatment of high resolution 2D images allowed the identification and separation of the BPS to evaluate total stylolitization density and insoluble thickness as an indirect measure of the dissolved volume, with respect to the morphology of the BPS considered. Based on the morphology of the BPS roughness, we used roughness signal analysis method to reconstruct the vertical paleo-stress (paleo-depth) recorded by the BPS during chemical compaction. The comparison between amount of compaction and dissolved volume as a function of the macro- and micro-facies, as well as estimates of maximum paleodepth of burial, deepen our knowledge of the factors controlling BPS development, the total thickness of carbonate dissolved and the occurrence of induced cementation in sedimentary basins.

Tectonostratigraphic reconstruction Cretaceous volcano-sedimentary in the northwestern Andes: from extensional tectonics to arc accretion.

NASA Astrophysics Data System (ADS)

Zapata, S.; Patino, A. M.; Cardona, A.; Mejia, D.; Leon, S.; Jaramillo, J. S.; Valencia, V.; Parra, M.; Hincapie, S.

2014-12-01

Active continental margins characterized by continuous convergence experienced overimposed tectonic configurations that allowed the formation of volcanic arcs, back arc basins, transtensional divergent tectonics or the accretion of exotic volcanic terranes. Such record, particularly the extensional phases, can be partially destroyed and obscure by multiple deformational events, the accretion of exotic terranes and strike slip fragmentation along the margin. The tectonic evolution of the northern Andes during the Mesozoic is the result of post Pangea extension followed by the installation of a long-lived Jurassic volcanic arc (209 - 136 ma) that apparently stops between 136 Ma and 110 Ma. The Quebradagrande Complex has been define as a single Lower Cretaceous volcano-sedimentary unit exposed in the western flank of the Central Cordillera of the Colombian Andes that growth after the Late Jurassic to Early Cretaceous magmatic hiatus. The origin of this unit have been related either to an oceanic volcanic arc or a marginal basin environment. The existence of such contrasting models reflect the regional perspective followed in published studies and the paucity of detail analysis of the volcano-sedimentary sequences.We integrate multiple approaches including structural mapping, stratigraphy, geochemistry, U-Pb provenance and geochronology to improve the understanding of this unit and track the earlier phases of accumulation that are mask on the overimposed tectonic history. Our preliminary results suggest the existence of different volcano-sedimentary units that accumulated between 100 Ma and 82 Ma.The older Lower Cretaceous sequences was deposited over Triassic metamorphic continental crust and include a upward basin deepening record characterized by thick fan delta conglomerates, followed by distal turbidites and a syn-sedimentary volcanic record at 100 ma. The other sequence include a 85 - 82 Ma fringing arc that was also formed close to the continental margin or associated with a continental terrane.This two volcano-sedimentary domains were finally juxtaposed due to the collision with an allochthonous oceanic arc that collide with the Continental margin in the Late Cretaceous marking the initiation of the Andean Orogeny.

Development and Exploitation of Low Enthalpy Geothermal Systems, Example of "The Dogger" in the Paris Basin, France

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rojas, J.; Menjoz, A.; Martin, J.C.

1987-01-20

A feature of French geothermal engineering is the development of industrial projects in normal gradient, non-convective areas. The economic feasibility of exploiting wells producing between 150 and 350 m{sup 3}/h at temperatures from 55° to 85° from depths of 1,500 to 2,000 meters, in sedimentary basins with normal gradient, for direct heat production has been proved by 50 plants providing heating for over 500,000 people during the last few years. This opens new possibilities for geothermal energy development the world over, in particular for areas where heat consumption is higher than 2,500 Tons oil equivalent (Toe)/year over several square kilometers.more » The recent and rapid development of geothermal projects in France, in particular in the Paris Basin has provided much more information on the characteristics of the Jurassic Dogger, which is the unit tapped by geothermal doublets (one production and one injection well). Detailed study of the Dogger reservoir in the Paris Basin is one of the main objectives of the IMRG research and development program drawn up in 1983. The preliminary results presented here are oriented towards (1) improved knowledge of the potential geothermal resources, and (2) analysis of optimum development conditions. 1 tab., 7 refs., 9 figs.« less

Formation and tectonic evolution of the Pattani Basin, Gulf of Thailand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bustin, R.M.; Chonchawalit, A.

The stratigraphic and structural evolution of the Pattani Basin, the most prolific petroleum basin in Thailand, reflects the extensional tectonic regime of continental Southeast Asia. E-W extension resulting from the northward collision of India with Eurasia since the Early Tertiary resulted in the formation of a series of N-S-trending sedimentary basins, which include the Pattani Basin. The sedimentary succession in the Pattani Basin is divisible into synrift and postrift sequences. Deposition of the synrift sequence accompanied rifting and extension, with episodic block faulting and rapid subsidence. The synrift sequence comprises three stratigraphic units: (1) Upper Eocene to Lower Olikgocene alluvial-fan,more » braided-river, and floodplain deposits; (2) Upper oligocene to Lowe Miocene floodplain and channel deposits; and (3) a Lower Miocene regressive package consisting of marine to nonmarine sediments. Post-rift succession comprises: (1) a Lower to Middle Miocene regressive package of shallow marine sediments through floodplain and channel deposits; (2) an upper Lower Miocene transgressive sequence; and (3) and Upper Miocene to Pleistocene transgressive succession. The post-rift phase is characterized by slower subsidence and decreased sediment influx. The present-day shallow-marine condition in the Gulf of Thailand is the continuation of this latest transgressive phase. The subsidence and thermal history of the Pattani Basin is consistent with a nonuniform lithospheric-stretching model. The amount of extension as well as surface heat flow generally increases from the margin to the basin center. The crustal stretching factor ({beta}) varies form 1.3 at the basin margin to 2.8 in the center. The subcrustal stretching factor ({delta}) ranges from 1.3 at the basin margin to more than 3.0 in the basin center. 31 refs., 13 figs., 4 tabs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keese, G.O.

Nearly half of the total area of the Republic of Ghana is covered by sedimentary rocks. These rocks are found mainly in four different parts of the country: Tano basin, Keta basin, Voltaian basin, and the continental shelf. Because oil seeps in saturated superficial sands were found in the Tano basin, efforts to find oil in Ghana started as far back as 1896 in this basin, which is located at the extreme southwestern part of Ghana and has an area of 1165 km/sup 2/ (450 mi/sup 2/). The Keta basin, located at the extreme southeastern part of Ghana, has anmore » area of 2200 km/sup 2/ (850 mi/sup 2/). The continental shelf of Ghana is at the southern part of the country and has an area of 27,562 km/sup 2/ (10,640 mi/sup 2/). The possibility of finding oil and/or gas at the extreme western part of the continental shelf cannot be overemphasized. The expansive Voltaian sedimentary basin, located in the central part of Ghana, covers an area of about 103,600 km/sup 2/ (40,000 mi/sup 2/). Although no trace of hydrocarbon was found in the only well that has been drilled so far in this basin, the presence of traces of bitumen in some parts of the basin indicates that, despite of its age, the basin might prove to be an oil province. The recent discovery of oil in the Ivory Coast means that it is possible to find oil or gas in Ghana, inasmuch as Ghana's petroleum potential is closely associated with that of the Ivory Coast basin, which extends for 560 km (300 mi) along the entire Ivory Coast and persists eastward into Ghana for an additional 320 km (200 mi), terminating in the area directly west of Accra.« less

Architecture and tectono-stratigraphic evolution of the intramontane Baza Basin (Bétics, SE-Spain): Constraints from seismic imaging

NASA Astrophysics Data System (ADS)

Haberland, Christian; Gibert, Luis; Jurado, María José; Stiller, Manfred; Baumann-Wilke, Maria; Scott, Gary; Mertz, Dieter F.

2017-07-01

The Baza basin is a large Neogene intramontane basin in the Bétic Cordillera of southern Spain that formed during the Tortonian (late Miocene). The Bétic Cordillera was produced by NW-SE oblique convergence between the Eurasian and African Plates. Three seismic reflection lines (each 18 km long; vibroseis method) were acquired across the Baza basin to reveal the architecture of the sedimentary infill and faulting during basin formation. We applied rather conventional CDP data processing followed by first arrival P-wave tomography to provide complementary structural information and establish velocity models for the post-stack migration. These images show a highly asymmetric structure for the Basin with sediments thickening westward, reaching a maximum observed thickness of > 2200 m near the governing Baza Fault zone (BFZ). Three major seismic units (including several subunits) on top of the acoustic basement could be identified. We use stratigraphic information from the uplifted block of the BFZ and other outcrops at the basin edges together with available information from neighboring Bétic basins to tentatively correlate the seismic units to the known stratigraphy in the area. Until new drilling or surface outcrop data is not available, this interpretation is preliminary. The seismic units could be associated to Tortonian marine deposits, and latest Miocene to Pleistocene continental fluvio-lacustrine sediments. Individual strands of the BFZ truncate the basin sediments. Strong fault reflections imaged in two lines are the product of the large impedance contrast between sedimentary fill and basement. In the central part of the Basin several basement faults document strong deformation related to the early stages of basin formation. Some of these faults can be traced up to the shallowest imaged depth levels indicating activity until recent times.

New vitrinite reflectance data for the Wind River Basin, Wyoming

USGS Publications Warehouse

Pawlewicz, Mark J.; Finn, Thomas M.

2013-01-01

The Wind River Basin is a large Laramide (Late Cretaceous through Eocene) structural and sedimentary basin that encompasses about 7,400 square miles in central Wyoming. The basin is bounded by the Washakie Range and Owl Creek and southern Bighorn Mountains on the north, the Casper arch on the east and northeast, and the Granite Mountains on the south, and Wind River Range on the west. The purpose of this report is to present new vitrinite reflectance data collected mainly from Cretaceous marine shales in the Wind River Basin to better characterize their thermal maturity and hydrocarbon potential.

New age constraints on the palaeoenvironmental evolution of the late Paleozoic back-arc basin along the western Gondwana margin of southern Peru

NASA Astrophysics Data System (ADS)

Boekhout, F.; Reitsma, M. J.; Spikings, R.; Rodriguez, R.; Ulianov, A.; Gerdes, A.; Schaltegger, U.

2018-03-01

The tectonic evolution of the western Gondwana margin during Pangaea amalgation is recorded in variations in the Permo-Carboniferous back-arc basin sedimentation of Peru. This study provides the first radiometric age constraints on the volcanic and sedimentary sequences of south-central eastern Peru up to the western-most tip of Bolivia, and now permits the correlation of lateral facies variations to the late Paleozoic pre-Andean orogenic cycle. The two phases of Gondwanide magmatism and metamorphism at c. 315 Ma and c. 260 Ma are reflected in two major changes in this sedimentary environment. Our detrital U-Pb zircon ages demonstrate that the timing of Ambo Formation deposition corroborates the Late Mississipian age estimates. The transition from the Ambo to the Tarma Formation around the Middle Pennsylvanian Early Gondwanide Orogeny (c. 315 Ma) represents a relative deepening of the basin. Throughout the shallow marine deposits of the Tarma Formation evidence for contemporaneous volcanism becomes gradually more pronounced and culminates around 312 - 309 Ma. Continuous basin subsidence resulted in a buildup of platform carbonates of the Copacabana Formation. Our data highlights the presence of a previously unrecognized phase of deposition of mainly fluvial sandstones and localized volcanism (281-270 Ma), which we named ´Oqoruro Formation'. This sedimentary succession was previously miss-assigned to the so-called Mitu Group, which has recently been dated to start deposition in the Middle Triassic (∼245-240 Ma). The emersion of this marine basin coincides with the onset of a major plutonic pulse related to the Late Gondwanide Orogeny (c. 260). Exhumation lead to the consequent retreat of the epeiric sea to the present-day sub-Andean region, and the coeval accumulation of the fluvial Oqoruro Formation in south eastern Peru. These late Paleozoic palaeoenvironmental changes in the back-arc basins along the western Gondwana margin of southern reflect changes in tectonic plate reorganization in a long-lived Paleozoic accretionary orogeny.

Mongolian Oil Shale, hosted in Mesozoic Sedimentary Basins

NASA Astrophysics Data System (ADS)

Bat-Orshikh, E.; Lee, I.; Norov, B.; Batsaikhan, M.

2016-12-01

Mongolia contains several Mesozoic sedimentary basins, which filled >2000 m thick non-marine successions. Late Triassic-Middle Jurassic foreland basins were formed under compression tectonic conditions, whereas Late Jurassic-Early Cretaceous rift valleys were formed through extension tectonics. Also, large areas of China were affected by these tectonic events. The sedimentary basins in China host prolific petroleum and oil shale resources. Similarly, Mongolian basins contain hundreds meter thick oil shale as well as oil fields. However, petroleum system and oil shale geology of Mongolia remain not well known due to lack of survey. Mongolian oil shale deposits and occurrences, hosted in Middle Jurassic and Lower Cretaceous units, are classified into thirteen oil shale-bearing basins, of which oil shale resources were estimated to be 787 Bt. Jurassic oil shale has been identified in central Mongolia, while Lower Cretaceous oil shale is distributed in eastern Mongolia. Lithologically, Jurassic and Cretaceous oil shale-bearing units (up to 700 m thick) are similar, composed mainly of alternating beds of oil shale, dolomotic marl, siltstone and sandstone, representing lacustrine facies. Both Jurassic and Cretaceous oil shales are characterized by Type I kerogen with high TOC contents, up to 35.6% and low sulfur contents ranging from 0.1% to 1.5%. Moreover, S2 values of oil shales are up to 146 kg/t. The numbers indicate that the oil shales are high quality, oil prone source rocks. The Tmax values of samples range from 410 to 447, suggesting immature to early oil window maturity levels. PI values are consistent with this interpretation, ranging from 0.01 to 0.03. According to bulk geochemistry data, Jurassic and Cretaceous oil shales are identical, high quality petroleum source rocks. However, previous studies indicate that known oil fields in Eastern Mongolia were originated from Lower Cretaceous oil shales. Thus, further detailed studies on Jurassic oil shale and its petroleum potential are required.

Geological timing and duration of methane seepage in different sedimentary and tectonic settings in the Lower Congo Basin

NASA Astrophysics Data System (ADS)

Wenau, S.; Spiess, V.

2016-12-01

Methane seepage sites have been investigated in the Lower Congo Basin using seismo-acoustic methods in combination with geological and geochemical sampling. Pockmarks were observed in different areas of the Lower Congo Basin that are affected by different styles of salt-tectonic deformation and sedimentary input. At the salt front in the southern part of the basin, methane seepage shifts continuously westwards as previously undeformed sediments are affected by westward moving salt. Older seepage sites to the East are cut off from methane supply in the process of continuing salt-tectonic deformation. The initiation of gas accumulation and seepage directly at the deformation front is expected in the late Miocene due to salt-induced uplift. In the northern part of the basin on the lower slope, methane seepage is focused along salt-tectonic faults connecting Pliocene fan deposits to the seafloor, breaching the hemipelagic seal. These sites show indications for continuing seepage for the last 640 kyrs. Such long term seepage activity may be due to the lack of polygonal faults in the hemipelagic seal, focusing gas migration on fewer, salt-tectonic faults. Westward of the salt front, seepage features include the Regab pockmark where a potential reservoir in an Early Pleistocene channel flank is connected to the seafloor feature via a seismic chimney. Seepage activity in this area is also documented to be continuous over geologic time scales by seafloor and sub-seafloor seepage indications such as chimneys, pockmarks and buried seepage features. The Lower Congo Basin thus documents the longevity of seepage processes in the context of various tectonic and sedimentary regimes on a passive continental margin. Indications of the duration of seepage activity at individual sites may be used for methane budgeting in combination with emission rates estimated for typical seepage sites.

Sedimentary and tectonic evolution of the southern Qiangtang basin: Implications for the Lhasa-Qiangtang collision timing

NASA Astrophysics Data System (ADS)

Ma, Anlin; Hu, Xiumian; Garzanti, Eduardo; Han, Zhong; Lai, Wen

2017-07-01

The Mesozoic stratigraphic record of the southern Qiangtang basin in central Tibet records the evolution and closure of the Bangong-Nujiang ocean to the south. The Jurassic succession includes Toarcian-Aalenian shallow-marine limestones (Quse Formation), Aalenian-Bajocian feldspatho-litho-quartzose to feldspatho-quartzo-lithic sandstones (shallow-marine Sewa Formation and deep-sea Gaaco Formation), and Bathonian outer platform to shoal limestones (Buqu Formation). This succession is truncated by an angular unconformity, overlain by upper Bathonian to lower Callovian fan-delta conglomerates and litho-quartzose to quartzo-lithic sandstones (Biluoco Formation) and Callovian shoal to outer platform limestones (Suowa Formation). Sandstone petrography coupled with detrital-zircon U-Pb and Hf isotope analysis indicate that the Sewa and Gaaco formations contain intermediate to felsic volcanic detritus and youngest detrital zircons (183-170 Ma) with ɛHf(t) ranging widely from +13 to -25, pointing to continental-arc provenance from igneous rocks with mixed mantle and continental-crust contributions. An arc-trench system thus developed toward the end of the Early Jurassic, with the southern Qiangtang basin representing the fore-arc basin. Above the angular unconformity, the Biluoco Formation documents a change to dominant sedimentary detritus including old detrital zircons (mainly >500 Ma ages in the lower part of the unit) with age spectra similar to those from Paleozoic strata in the central Qiangtang area. A major tectonic event with intense folding and thrusting thus took place in late Bathonian time (166 ± 1 Ma), when the Qiangtang block collided with another microcontinental block possibly the Lhasa block.

Calculation of thermal conductivity, thermal diffusivity and specific heat capacity of sedimentary rocks using petrophysical well logs

NASA Astrophysics Data System (ADS)

Fuchs, Sven; Balling, Niels; Förster, Andrea

2015-12-01

In this study, equations are developed that predict for synthetic sedimentary rocks (clastics, carbonates and evapourates) thermal properties comprising thermal conductivity, specific heat capacity and thermal diffusivity. The rock groups are composed of mineral assemblages with variable contents of 15 major rock-forming minerals and porosities of 0-30 per cent. Petrophysical properties and their well-logging-tool-characteristic readings were assigned to these rock-forming minerals and to pore-filling fluids. Relationships are explored between each thermal property and other petrophysical properties (density, sonic interval transit time, hydrogen index, volume fraction of shale and photoelectric absorption index) using multivariate statistics. The application of these relations allows computing continuous borehole profiles for each rock thermal property. The uncertainties in the prediction of each property vary depending on the selected well-log combination. Best prediction is in the range of 2-8 per cent for the specific heat capacity, of 5-10 per cent for the thermal conductivity, and of 8-15 for the thermal diffusivity, respectively. Well-log derived thermal conductivity is validated by laboratory data measured on cores from deep boreholes of the Danish Basin, the North German Basin, and the Molasse Basin. Additional validation of thermal conductivity was performed by comparing predicted and measured temperature logs. The maximum deviation between these logs is <3 °C. The thermal-conductivity calculation allowed an evaluation of the depth range in which the palaeoclimatic effect on the subsurface temperature field can be observed in the North German Basin. This effect reduces the surface heat-flow density by 25 mW m-2.

Modeling the effects of source and path heterogeneity on ground motions of great earthquakes on the Cascadia Subduction Zone Using 3D simulations

USGS Publications Warehouse

Delorey, Andrew; Frankel, Arthur; Liu, Pengcheng; Stephenson, William J.

2014-01-01

We ran finite‐difference earthquake simulations for great subduction zone earthquakes in Cascadia to model the effects of source and path heterogeneity for the purpose of improving strong‐motion predictions. We developed a rupture model for large subduction zone earthquakes based on a k−2 slip spectrum and scale‐dependent rise times by representing the slip distribution as the sum of normal modes of a vibrating membrane.Finite source and path effects were important in determining the distribution of strong motions through the locations of the hypocenter, subevents, and crustal structures like sedimentary basins. Some regions in Cascadia appear to be at greater risk than others during an event due to the geometry of the Cascadia fault zone relative to the coast and populated regions. The southern Oregon coast appears to have increased risk because it is closer to the locked zone of the Cascadia fault than other coastal areas and is also in the path of directivity amplification from any rupture propagating north to south in that part of the subduction zone, and the basins in the Puget Sound area are efficiently amplified by both north and south propagating ruptures off the coast of western Washington. We find that the median spectral accelerations at 5 s period from the simulations are similar to that of the Zhao et al. (2006) ground‐motion prediction equation, although our simulations predict higher amplitudes near the region of greatest slip and in the sedimentary basins, such as the Seattle basin.

Seismic amplification within the Seattle Basin, Washington State: Insights from SHIPS seismic tomography experiments

USGS Publications Warehouse

Snelson, C.M.; Brocher, T.M.; Miller, K.C.; Pratt, T.L.; Trehu, A.M.

2007-01-01

Recent observations indicate that the Seattle sedimentary basin, underlying Seattle and other urban centers in the Puget Lowland, Washington, amplifies long-period (1-5 sec) weak ground motions by factors of 10 or more. We computed east-trending P- and S-wave velocity models across the Seattle basin from Seismic Hazard Investigations of Puget Sound (SHIPS) experiments to better characterize the seismic hazard the basin poses. The 3D tomographic models, which resolve features to a depth of 10 km, for the first time define the P- and S-wave velocity structure of the eastern end of the basin. The basin, which contains sedimentary rocks of Eocene to Holocene, is broadly symmetric in east-west section and reaches a maximum thickness of 6 km along our profile beneath north Seattle. A comparison of our velocity model with coincident amplification curves for weak ground motions produced by the 1999 Chi-Chi earthquake suggests that the distribution of Quaternary deposits and reduced velocity gradients in the upper part of the basement east of Seattle have significance in forecasting variations in seismic-wave amplification across the basin. Specifically, eastward increases in the amplification of 0.2- to 5-Hz energy correlate with locally thicker unconsolidated deposits and a change from Crescent Formation basement to pre-Tertiary Cascadia basement. These models define the extent of the Seattle basin, the Seattle fault, and the geometry of the basement contact, giving insight into the tectonic evolution of the Seattle basin and its influence on ground shaking.

Origin and time-space distribution of hydrothermal systems in east-central Australian sedimentary basins: Constraints from illite geochronology and isotope geochemistry.

NASA Astrophysics Data System (ADS)

Uysal, I. Tonguç

2016-04-01

Some well-known precious mineral deposits and hydrocarbon resources occur extensively in east-central Australian sedimentary Basins. The metal occurrences are abundant in northwestern and eastern part of Queensland, whereas no significant deposits are known in large areas further south, which may, however, be hidden beneath the Jurassic-Cretaceous sedimentary basins. Important hydrocarbon resources exist within the Jurassic-Cretaceous sedimentary rocks at relatively shallow depths, of which the distribution represent zones of high paleo-geothermal gradients. This study examines the time-space distribution in relation to the regional tectonic history of concealed metal deposits and areas of high paleo-geothermal gradient leading to hydrocarbon maturation. To this end, authigenic illitic clay minerals representing various locations and stratigraphic depths in east-central Australia were investigated, of which the Rb-Sr and Ar-Ar geochronology and stable isotope geochemistry assist in delineating zones of hydrothermal systems responsible for hydro-carbon maturation/migration and potentially ore deposition. The Late Carboniferous - Early Permian crustal extension that affected large areas of eastern Australia and led to the epithermal mineralisations (e.g., the Drummond Basin) is also recorded in northern South Australia and southwest Queensland. A Late Triassic - Early Jurassic tectonic event being responsible for coal maturation and gas generation in the Bowen Basin and the epithermal mineralisation in the North Arm goldfield in SE Queensland likewise affected the areas much further west in Queensland. Some illites from the basement in outback Queensland and fault gouges from the Demon Fault in NE New South Wales yield younger Rb-Sr and Ar-Ar ages indicating the effect of hydrothermal processes as a result of a Middle-Upper Jurassic tectonic event. The majority of illite samples from the crystalline basement rocks, Permian Cooper Basin, and Jurassic-Cretaceous Eromanga Basin from all over east-central Australia give Cretaceous ages (~130 to ~60 Ma) reflecting episodic hydrothermal events restricted to certain tectonic zones. The Cretaceous events were responsible for the hydro-carbon generation/maturation in the Cooper, Eromanga, and Gunnedah Basins and deposition of some Au and basemetal resources in the eastern part of Queensland. The stable isotope composition of the Late Triassic - Early Jurassic illites in eastern Queensland and all mid-late Cretaceous illites from outback and eastern Australia is distinctively different with low 18O and D values indicating meteoric-hydrothermal systems due to extensional tectonics. Results of this study suggest that illite geochronology and geochemistry is a powerful tool in delineation of concealed hydrothermal systems that were responsible for ore generation and hydrocarbon/maturation and migration.

Paleocurrents of the Middle-Upper Jurassic strata in the Paradox Basin, Colorado, inferred from anisotropy of magnetic susceptibility (AMS)

NASA Astrophysics Data System (ADS)

Ejembi, J. I.; Ferre, E. C.; Potter-McIntyre, S. L.

2017-12-01

The Middle-Upper Jurassic sedimentary strata in the southwestern Colorado Plateau recorded pervasive eolian to fluvio-lacustrine deposition in the Paradox Basin. While paleocurrents preserved in the Entrada Sandstone, an eolian deposition in the Middle Jurassic, has been well constrained and show a northwesterly to northeasterly migration of ergs from the south onto the Colorado Plateau, there is yet no clear resolution of the paleocurrents preserved in the Wanakah Formation and Tidwell Member of the Morrison Formation, both of which are important sedimentary sequences in the paleogeographic framework of the Colorado Plateau. New U-Pb detrital zircon geochronology of sandstones from these sequences suggests that an abrupt change in provenance occurred in the early Late Jurassic, with sediments largely sourced from eroding highlands in central Colorado. We measured the anisotropy of magnetic susceptibility (AMS) of sediments in oriented sandstone samples from these three successive sequences; first, to determine the paleocurrents from the orientations of the AMS fabrics in order to delineate the source area and sediments dispersal pattern and second, to determine the depositional mechanisms of the sediments. Preliminary AMS data from two study sites show consistency and clustering of the AMS axes in all the sedimentary sequences. The orientations of the Kmin - Kint planes in the Entrada Sandstone sample point to a NNE-NNW paleocurrent directions, which is in agreement with earlier studies. The orientations of the Kmin - Kint planes in the Wanakah Formation and Tidwell Member samples show W-SW trending paleocurrent directions, corroborating our hypothesis of a shift in provenance to the eroding Ancestral Front Range Mountain, located northeast of the Paradox Basin, during the Late Jurassic. Isothermal remanence magnetization (IRM) of the samples indicate that the primary AMS carriers are detrital, syndepositional ferromagnetic minerals. Thus, we contend that AMS can be successfully deployed in constraining paleocurrents in lacustrine sedimentary strata, which lacks traditional sedimentary structures for paleocurrent analyses.

Acoustic stratigraphy of Bear Lake, Utah-Idaho: late Quaternary sedimentation patterns in a simple half-graben

USGS Publications Warehouse

Colman, Steven M.

2006-01-01

A 277-km network of high-resolution seismic-reflection profiles, supplemented with a sidescan-sonar mosaic of the lake floor, was collected in Bear Lake, Utah–Idaho, in order to explore the sedimentary framework of the lake's paleoclimate record. The acoustic stratigraphy is tied to a 120 m deep, continuously cored drill hole in the lake. Based on the age model for the drill core, the oldest continuously mapped acoustic reflector in the data set has an age of about 100 ka, although older sediments were locally imaged. The acoustic stratigraphy of the sediments below the lake indicates that the basin developed primarily as a simple half-graben, with a steep normal-fault margin on the east and a flexural margin on the west. As expected for a basin controlled by a listric master fault, seismic reflections steepen and diverge toward the fault, bounding eastward-thickening sediment wedges. Secondary normal faults west of the master fault were imaged beneath the lake and many of these faults show progressively increasing offset with depth and age. Several faults cut the youngest sediments in the lake as well as the modern lake floor. The relative simplicity of the sedimentary sequence is interrupted in the northwestern part of the basin by a unit that is interpreted as a large (4 × 10 km) paleodelta of the Bear River. The delta overlies a horizon with an age of about 97 ka, outcrops at the lake floor and is onlapped by much of the uppermost sequence of lake sediments. A feature interpreted as a wave-cut bench occurs in many places on the western side of the lake. The base of this bench occurs at a depth (22–24 m) similar to that (20–25 m) of the distal surface of the paleodelta. Pinch-outs of sedimentary units are common in relatively shallow water on the gentle western margin of the basin and little Holocene sediment has accumulated in water depths of less than 30 m. On the steep eastern margin of the basin, sediments commonly onlap the hanging wall of the East Bear Lake Fault. However, no major erosional or depositional features suggestive of shoreline processes were observed on acoustic profiles in water deeper than about 20–25 m.

Excitation of secondary Love and Rayleigh waves in athree-dimensional sedimentary basin evaluated by the direct boundary element method with normal modes

NASA Astrophysics Data System (ADS)

Hatayama, Ken; Fujiwara, Hiroyuki

1998-05-01

This paper aims to present a new method to calculate surface waves in 3-D sedimentary basin models, based on the direct boundary element method (BEM) with vertical boundaries and normal modes, and to evaluate the excitation of secondary surface waves observed remarkably in basins. Many authors have so far developed numerical techniques to calculate the total 3-D wavefield. However, the calculation of the total wavefield does not match our purpose, because the secondary surface waves excited on the basin boundaries will be contaminated by other undesirable waves. In this paper, we prove that, in principle, it is possible to extract surface waves excited on part of the basin boundaries from the total 3-D wavefield with a formulation that uses the reflection and transmission operators defined in the space domain. In realizing this extraction in the BEM algorithm, we encounter the problem arising from the lateral and vertical truncations of boundary surfaces extending infinitely in the half-space. To compensate the truncations, we first introduce an approximate algorithm using 2.5-D and 1-D wavefields for reference media, where a 2.5-D wavefield means a 3-D wavefield with a 2-D subsurface structure, and we then demonstrate the extraction. Finally, we calculate the secondary surface waves excited on the arc shape (horizontal section) of a vertical basin boundary subject to incident SH and SV plane waves propagating perpendicularly to the chord of the arc. As a result, we find that in the SH-incident case the Love waves are predominantly excited, rather than the Rayleigh waves and that in the SV-wave incident case the Love waves as well as the Rayleigh waves are excited. This suggests that the Love waves are more detectable than the Rayleigh waves in the horizontal components of observed recordings.

Early metal pollution in southwestern Europe: the former littoral lagoon of El Almarjal (Cartagena mining district, S.E. Spain).A sedimentary archive more than 8000 years old.

PubMed

Manteca, José-Ignacio; Ros-Sala, Milagros; Ramallo-Asensio, Sebastián; Navarro-Hervás, Francisca; Rodríguez-Estrella, Tomás; Cerezo-Andreo, Felipe; Ortiz-Menéndez, José-Eugenio; de-Torres, Trinidad; Martínez-Andreu, Miguel

2017-04-01

A borehole drilling campaign has allowed the study of a former littoral lagoon located next to the harbour city of Cartagena in South-East Spain (close to the Sierra de Cartagena polymetallic ore deposits). This lagoon, which developed during the Holocene, was first a shallow sedimentary marine environment and later evolved into a swampy semi-endorheic basin named "Almarjal" (after the Arab term from the fourteenth century). The lagoon eventually dried out and at present forms part of the substratum of the modern sector of the city urban area. The basin representative sediments are sapropelic black silty facies forming a continuous sedimentary archive, accounting for more than 8000 years of depositional phenomena. The geochemical study of these sediments, together with their absolute calibrated dating by 14 C, allows definition of successive stages of mining and metallurgical activities in the area. In turn, this information provides a more comprehensive perspective regarding metal pollution, particularly lead contamination during different periods of the Recent Prehistory and the Classical Age. The results indicate that the beginning of contamination by lead and other heavy metals occurred as early as 4500 years ago, when the Final Chalcolithic period was taking place in the South-East of the Iberian Peninsula. This finding provides further insights regarding the debate on the origins of lead mining and metallurgy in SE Spain.

Contemporary suspended sediment dynamics within two partly glacierized mountain drainage basins in western Norway (Erdalen and Bødalen, inner Nordfjord)

NASA Astrophysics Data System (ADS)

Beylich, Achim A.; Laute, Katja; Storms, Joep E. A.

2017-06-01

This paper focuses on environmental controls, spatiotemporal variability and rates of contemporary fluvial suspended sediment transport in the neighboring, partly glacierized and steep Erdalen (79.5 km2) and Bødalen (60.1 km2) drainage basins in the fjord landscape of the inner Nordfjord in western Norway. Field work, including extended samplings and measurements, was conducted since 2004 in Erdalen and since 2008 in Bødalen. The distinct intra- and inter-annual temporal variability of suspended sediment transport found is mostly controlled by meteorological events, with most suspended sediment transport occurring during pluvial events in autumn (September-November), followed by mostly thermally determined glacier melt in summer (July-August), and by mostly thermally determined snowmelt in spring (April-June). Extreme rainfall events (> 70 mm d- 1) in autumn can trigger significant debris-flow activity that can cause significant transfers of suspended sediments from ice-free surface areas with sedimentary covers into main stream channels and is particularly important for fluvial suspended sediment transport. In years with occurring relevant debris-flow activity the total annual drainage-basin wide suspended sediment yields are strongly determined by these single extreme events. The proportion of glacier coverage, followed by steepness of slopes, and degree of vegetation cover in ice-free surface areas with sedimentary covers are the main controls for the detected spatial variability of suspended sediment yields. The contemporary sediment supply from glacierized surface areas and the Jostedalsbreen ice cap through different defined outlet glaciers shows a high spatial variability. The fact that the mean annual suspended sediment yield of Bødalen is with 31.3 t km- 2 yr- 1 almost twice as high as the mean annual suspended sediment yield of Erdalen (16.4 t km- 2 yr- 1) is to a large extent explained by the higher proportion of glacier coverage in Bødalen (38% of the drainage basin surface area) as compared to Erdalen (18% of the drainage basin surface area) and by a significantly higher sediment yield from the glacierized area of the Bødalen drainage basin compared to the glacierized surface area in Erdalen. When looking at the total annual mass of suspended sediments being fluvially exported from both entire drainage basin systems, the total amount of suspended sediments coming from the ice-free drainage basin surface areas altogether dominates over the total amount of suspended sediments coming from the glacierized surface area of both drainage basins. Drainage-basin wide annual suspended sediment yields are rather low when compared with yields of other partly glacierized drainage basin systems in Norway and in other cold climate environments worldwide, which is mainly due to the high resistance of the predominant gneisses towards glacial erosion and weathering, the altogether only small amounts of sediments being available within the entire drainage basin systems, the stable and nearly closed vegetation cover in the ice-free surface areas with sedimentary covers, and the efficiency of proglacial lakes in trapping sediments supplied by defined outlet glaciers. Both contemporary and long-term suspended sediment yields are altogether supply-limited. Contemporary suspended sediment transport accounts for nearly two-thirds of the total fluvial transport and, accordingly, plays an important role within the sedimentary budgets of the entire Erdalen and Bødalen drainage basins.

Application of high resolution aeromagnetic data for basement topography mapping of Siluko and environs, southwestern Nigeria

NASA Astrophysics Data System (ADS)

Osinowo, Olawale O.; Akanji, Adesoji O.; Olayinka, Abel I.

2014-11-01

The discovery of hydrocarbon in commercial quantity in the Niger Delta, southern Nigeria, has since the early fifties shifted the attention of exploration/active geological studies from the Dahomey basin and the adjacent basement terrain in south-western Nigeria towards the south and this has left some gaps in information required for the discovery and exploitation of the economic potential of the region. This study mapped the Siluko transition zone in south-western Nigeria in terms of structures, geometry and basement topography with the object of providing requisite geological information that will engender interest in the exploration and exploitation of the numerous economic potentials of south-western part of Nigeria. Acquired high resolution aeromagnetic data were filtered, processed and enhanced, the resultant data were subjected to qualitative and quantitative magnetic interpretation, depth weighting analyses and modelling to generate the subsurface basement topography across the study area. The obtained results indicate regions of high and low magnetic anomalies with residual magnetic intensity values ranging from -100.8 nT to 100.9 nT. Euler Deconvolution indicates generally undulating basement topography with depth range of 125-1812 m. The basement relief is generally gentle and flat lying within the basement terrain with depth ranging from 125 to 500 m. However the sedimentary terrain is undulating and generally steeps south, down the basin with depth range of 300-1812 m. A basement topography model of the magnetic data constrained by Euler solutions correlate positively with the geology of the study area and indicates a generally increasing sedimentary deposits' thickness southward toward the western part of Dahomey basin. The revealed basement topography and structures as well as the delineated direction of continuous increase in thickness of sedimentary deposit provide insight to the controlling factor responsible for tar sand deposit and bitumen/oil shows associated with the study area. The results also point to the southern and south-western part of the basin as the appropriate direction to focus at for meaningful hydrocarbon potential development.

Development of the Archaean Mallina Basin, Pilbara Craton, northwestern Australia; a study of detrital and inherited zircon ages

NASA Astrophysics Data System (ADS)

Smithies, R. H.; Nelson, D. R.; Pike, G.

2001-06-01

SHRIMP U-Pb zircon dates are combined with an examination of the age distribution patterns and provenance of both detrital zircons and of zircon xenocrysts in granites to investigate the development of the Archaean Mallina Basin, in the granite-greenstone terrain of the Pilbara Craton, northwestern Australia. The oldest dated components of the basin are c. 3010 Ma volcaniclastic rocks in the western part of the area. New data indicate that siliciclastic turbidites that dominate the southern and eastern part of the basin were deposited at or after c. 2970 Ma but before c. 2955 Ma. Linking both the detrital zircon populations as well as zircon xenocrysts from granites that intruded the Mallina Basin to well-dated areas of the Pilbara granite-greenstone terrane indicates that the sediment was derived from the south, north, northwest, and east. The basin probably evolved primarily in an intracontinental setting between two elevated land masses to the southeast and northwest. Most of the rocks within the basin were folded before intrusion of granites, the oldest of which has been dated at 2954±4 Ma. Evidence of a second depositional cycle is provided by a maximum depositional age of 2941±9 Ma, indicated by a detrital zircon population from a sample of wacke from the southeast part of the Mallina Basin. This second depositional phase may have been related to renewed extension, and recycling of sedimentary rocks within the basin.

Effect of hydro mechanical coupling on natural fracture network formation in sedimentary basins

NASA Astrophysics Data System (ADS)

Ouraga, Zady; Guy, Nicolas; Pouya, Amade

2018-05-01

In sedimentary basin context, numerous phenomena, depending on the geological time span, can result in natural fracture network formation. In this paper, fracture network and dynamic fracture spacing triggered by significant sedimentation rate are studied considering mode I fracture propagation using a coupled hydro-mechanical numerical methods. The focus is put on synthetic geological structure under a constant sedimentation rate on its top. This model contains vertical fracture network initially closed and homogeneously distributed. The fractures are modelled with cohesive zone model undergoing damage and the flow is described by Poiseuille's law. The effect of the behaviour of the rock is studied and the analysis leads to a pattern of fracture network and fracture spacing in the geological layer.

Map showing depth to bedrock of the Tacoma and part of the Centralia 30' x 60' quadrangles, Washington

USGS Publications Warehouse

Buchanan-Banks, Jane M.; Collins, Donley S.

1994-01-01

The heavily populated Puget Sound region in the State of Washington has experienced moderate to large earthquakes in the recent past (Nuttli, 1952; Mullineaux and others, 1967). Maps showing thickness of unconsolidated sedimentary deposits are useful aids in delineating areas where damage to engineered structures can result from increased shaking resulting from these earthquakes. Basins containing thick deposits of unconsolidated materials can amplify earthquakes waves and cause far more damage to structures than the same waves passing through bedrock (Singh and others, 1988; Algermissen and others, 1985). Configurations of deep sedimentary basins can also cause reflection and magnification of earthquake waves in ways still not fully understood and presently under investigation (Frankel and Vidale, 1992).

Active faults of the Baikal depression

USGS Publications Warehouse

Levi, K.G.; Miroshnichenko, A.I.; San'kov, V. A.; Babushkin, S.M.; Larkin, G.V.; Badardinov, A.A.; Wong, H.K.; Colman, S.; Delvaux, D.

1997-01-01

The Baikal depression occupies a central position in the system of the basins of the Baikal Rift Zone and corresponds to the nucleus from which the continental lithosphere began to open. For different reasons, the internal structure of the Lake Baikal basin remained unknown for a long time. In this article, we present for the first time a synthesis of the data concerning the structure of the sedimentary section beneath Lake Baikal, which were obtained by complex seismic and structural investigations, conducted mainly from 1989 to 1992. We make a brief description of the most interesting seismic profiles which provide a rough idea of a sedimentary unit structure, present a detailed structural interpretation and show the relationship between active faults in the lake, heat flow anomalies and recent hydrothermalism.

Middle Pleistocene infill of Hinkley Valley by Mojave River sediment and associated lake sediment: Depositional architecture and deformation by strike-slip faults

USGS Publications Warehouse

Miller, David; Haddon, Elizabeth; Langenheim, Victoria; Cyr, Andrew J.; Wan, Elmira; Walkup, Laura; Starratt, Scott W.

2018-01-01

Hinkley Valley in the Mojave Desert, near Barstow about 140 km northeast of Los Angeles and midway between Victorville Valley and the Lake Manix basin, contains a thick sedimentary sequence delivered by the Mojave River. Our study of sediment cores drilled in the valley indicates that Hinkley Valley was probably a closed playa basin with stream inflow from four directions prior to Mojave River inflow. The Mojave River deposited thick and laterally extensive clastic wedges originating from the southern valley that rapidly filled much of Hinkley Valley. Sedimentary facies representing braided stream, wetland, delta, and lacustrine depositional environments all are found in the basin fill; in some places, the sequence is greater than 74 m (245 ft) thick. The sediment is dated in part by the presence of the ~631 ka Lava Creek B ash bed low in the section, and thus represents sediment deposition after Victorville basin was overtopped by sediment and before the Manix basin began to be filled. Evidently, upstream Victorville basin filled with sediment by about 650 ka, causing the ancestral Mojave River to spill to the Harper and Hinkley basins, and later to Manix basin.Initial river sediment overran wetland deposits in many places in southern Hinkley Valley, indicating a rapidly encroaching river system. These sediments were succeeded by a widespread lake (“blue” clay) that includes the Lava Creek B ash bed. Above the lake sediment lies a thick section of interlayered stream sediment, delta and nearshore lake sediment, mudflat and/or playa sediment, and minor lake sediment. This stratigraphic architecture is found throughout the valley, and positions of lake sediment layers indicate a successive northward progression in the closed basin. A thin overlapping sequence at the north end of the valley contains evidence for a younger late Pleistocene lake episode. This late lake episode, and bracketing braided stream deposits of the Mojave River, indicate that the river avulsed through the valley, rather than continuing toward Lake Manix, during the late Pleistocene. Two dextral strike-slip fault zones, the Lockhart and the Mt. General, fold and displace the distinctive stratigraphic units, as well as surficial late Pleistocene and Holocene deposits. The sedimentary architecture and the two fault zones provide a framework for evaluating groundwater flow in Hinkley Valley.

Long Period Seismic Waves Developped at Local Distances and Their Importance for EEWs

NASA Astrophysics Data System (ADS)

Kalkan Ertan, Esra; Pınar, Ali

2017-04-01

Long period ground motions is an highly importance topic nowadays because of the number of the large-scale structures increases day by day in metropolitan areas. Their effect on the large-scale structure (high rise buildings, suspension bridges, off-shore oil drilling platforms etc.) are more perceivable than small structures. Studies show that long period ground motions especially occurs in distant sedimentary basins with the help of the path effects. (Koketsu and Miyake, 2008) Period of the waves is ranging from several to ten seconds and that causes dramatic resonance and severe damage to the structures which are located in deep sedimentary basins (Furumura et al., 2013). There are so many examples of how destructive these waves can be. A devastating example is Mexico City, which is located 400 km away from the 1985 Michoacan Earthquake (Mw=8.0) epicenter, where 300 buldings collapsed and 800 buildings were demolished beyond repair. (Celebi et al, 1987). Another example is 2003 Tokachi-oki Earthquake associated with severe damage on large oil tanks, and fires lasting two days at the city of Tomakomani 250 km away from the source (Koketsu et al, 2005). Lots of studies revealed that the sedimentary basins amplifiy the long period seismic waves. In the case of Marmara Region, three important basins namely Çınarcık, Central and Tekirdaǧ Basins exist in Marmara Sea. The primary objective of the proposed study is to investigate if any relations exist between basins structures and generation of long period seismic waves which can be effective in Istanbul Metropolitan Area and develop reliable early warning applications or systems for structures which are under such risk. Three types of algorithms are in use for EEW applications used for this study, Virtual Seismologist, PRESTo and ELARMS2. The early warning signal is communicated to the appropriate server shut-down systems of the recipient facilities, that automatically decide proper action based on the alarm levels. The stations are located at basin-edges, outside and inside the basins. So we have a chance to compare the seismograms whether or not the earthquake generates long period ground motions and to send signals to early warning systems. Until now, we have a good example for long period seismic waves which was caused by North Aegean Earthquake on 24 May 2014 (Mw=6.9). It was located approximately 30 km north-west of Gökçeada Island and widely felt in İstanbul Metropolitan area. The earthquake epicenter was 300 km away from Istanbul, but the shaking duration of tall buildings was high up to 10 minutes. The travel time of the long period waves from the epicenter to the metropolitan area of Istanbul is about 85 seconds providing more than 50 seconds warning time. Although, the amplitude of the strong motion waveforms were small, the long period and the long duration of the velocity waveforms acquired at more than 100 strong motion stations within the city, explains to some degree the causatives of the long shaking duration of tall buildings.

Neoproterozoic rift basins and their control on the development of hydrocarbon source rocks in the Tarim Basin, NW China

NASA Astrophysics Data System (ADS)

Zhu, Guang-You; Ren, Rong; Chen, Fei-Ran; Li, Ting-Ting; Chen, Yong-Quan

2017-12-01

The Proterozoic is demonstrated to be an important period for global petroleum systems. Few exploration breakthroughs, however, have been obtained on the system in the Tarim Basin, NW China. Outcrop, drilling, and seismic data are integrated in this paper to focus on the Neoproterozoic rift basins and related hydrocarbon source rocks in the Tarim Basin. The basin consists of Cryogenian to Ediacaran rifts showing a distribution of N-S differentiation. Compared to the Cryogenian basins, those of the Ediacaran are characterized by deposits in small thickness and wide distribution. Thus, the rifts have a typical dual structure, namely the Cryogenian rifting and Ediacaran depression phases that reveal distinct structural and sedimentary characteristics. The Cryogenian rifting basins are dominated by a series of grabens or half grabens, which have a wedge-shaped rapid filling structure. The basins evolved into Ediacaran depression when the rifting and magmatic activities diminished, and extensive overlapping sedimentation occurred. The distributions of the source rocks are controlled by the Neoproterozoic rifts as follows. The present outcrops lie mostly at the margins of the Cryogenian rifting basins where the rapid deposition dominates and the argillaceous rocks have low total organic carbon (TOC) contents; however, the source rocks with high TOC contents should develop in the center of the basins. The Ediacaran source rocks formed in deep water environment of the stable depressions evolving from the previous rifting basins, and are thus more widespread in the Tarim Basin. The confirmation of the Cryogenian to Ediacaran source rocks would open up a new field for the deep hydrocarbon exploration in the Tarim Basin.

Sedimentation patterns in the Barberton Mountain Land, South Africa, and the Pilbara Block, Australia: Evidence for Archean rifted continental margins

NASA Astrophysics Data System (ADS)

Eriksson, Kenneth A.

1982-01-01

Archean supracrustal sequences in the Barberton Mountain Land, South Africa, and the Pilbara Block, Australia, consist of lower volcanic and upper dominantly terrigenous clastic intervals. As evidenced by the paleoenvironments of intercalated sedimentary horizons, volcanism occurred mainly in shallow waters. The overlying ca 3.3 Ga sedimentary intervals contain various common as well as unique paleoenvironments, the understanding of which places significant constraints on Archean crustal models. Lateral and vertical associations of inferred paleoenvironments are used to interpret the geotectonic history of the Archean depositories. The early sedimentary history of the greenstone belts is characterized by terrestrial and subaqueous graben-fill associations of facies related to the initial rift stage of basin development. Continued rifting and initial spreading produced submarine grabens within which ironformations accumulated in response to waning volcanism. Source area uplift resulted in progradation of submarine fans across the basinal chemical sediments. The turbidites are gradational directly into braided alluvial sediments, in part of fan delta origin, suggesting that the continental to marine transition occurred along a narrow continental shelf. In the Barberton Mountain Land the steep-rift margin was succeeded by the development of a stable continental shelf or shelf rise margin through progradation of the turbidite wedge possibly in association with a eustatic rise in sea-level related to continued spreading. On this shelf extensive tidal, deltaic and barrier beach sediments accumulated. Sedimentation was terminated by closure of the passive margin oceans. The late-Archean Pongola Supergroup in South Africa is considered to be the late-orogenic molasse response to this closure and represents the completion of the Wilson cycle.

Inventory of Shale Formations in the US, Including Geologic, Hydrological, and Mechanical Characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobson, Patrick; Houseworth, James

2013-11-22

The objective of this report is to build upon previous compilations of shale formations within many of the major sedimentary basins in the US by developing GIS data delineating isopach and structural depth maps for many of these units. These data are being incorporated into the LANL digital GIS database being developed for determining host rock distribution and depth/thickness parameters consistent with repository design. Methods were developed to assess hydrological and geomechanical properties and conditions for shale formations based on sonic velocity measurements.

Vein mineralizations - archives of paleo-fluid systems in the Thuringian basin (Germany)

NASA Astrophysics Data System (ADS)

Abratis, M.; Brey, M.; Fritsch, S.; Majzlan, J.; Viereck-Götte, L.

2012-04-01

We investigate vein mineralizations within and around the Thuringian basin (Germany) in order to characterize paleo-fluid systems that have been active in the basin. By investigating the composition, temperature, origin, age and evolution of paleo-fluids in the Thuringian basin as a model case, we aim for comprehensive understanding of the character of mineralized fluid systems in sedimentary basins in general and their evolution over geological time scales. Mineralizations along faults are archives for the composition of fluids which intruded the basin and circulated within it millions of years ago. These mineralizations give information on the physical and chemical characteristics of the related fluids as well as on their evolution with time during basin evolution. Mapping of mineralizations in space and time and comparison with the present-day fluid circulation system allows for recognition of the paleo-fluid dynamics and high temperature fluid influx pathways. The chemical characteristics of vein-related mineralizations are proxies for the paleo-fluid sources and their solution load. Methods implied comprise bulk rock analyses (petrography, XRD, XRF, ICP-MS), mineral analyses (EPMA, LA-ICP-MS), fluid inclusion measurements (microthermometry, Raman spectroscopy, ion chromatography) and isotope studies (O, H, C, S, Sr). Vein-related mineralizations within the Mesozoic sediments of the basin occur predominantly along WNW-ESE trending fault systems and comprise mainly carbonates and sulfates. Mineralizations within the basin-confining uplifted Variscan basement rocks and lowermost sedimentary units (Zechstein) show also (Fe-, Cu-, Zn-, As-, Sb-) sulfides, (Fe-, Mn-) oxides, fluorite and barite. The present study is part of INFLUINS, a BMBF-funded project bundle which is dedicated to comprehensive description and understanding of the fluid systems within the Thuringian basin in time and space.

The role of post-collisional strike-slip tectonics in the geological evolution of the late Neoproterozoic volcano-sedimentary Guaratubinha Basin, southern Brazil

NASA Astrophysics Data System (ADS)

Barão, Leonardo M.; Trzaskos, Barbara; Vesely, Fernando F.; de Castro, Luís Gustavo; Ferreira, Francisco J. F.; Vasconcellos, Eleonora M. G.; Barbosa, Tiago C.

2017-12-01

The Guaratubinha Basin is a late Neoproterozoic volcano-sedimentary basin included in the transitional-stage basins of the South American Platform. The aim of this study is to investigate its tectonic evolution through a detailed structural analysis based on remote sensing and field data. The structural and aerogeophysics data indicate that at least three major deformational events affected the basin. Event E1 caused the activation of the two main basin-bounding fault zones, the Guaratubinha Master Fault and the Guaricana Shear Zone. These structures, oriented N20-45E, are associated with well-defined right-lateral to oblique vertical faults, conjugate normal faults and vertical flow structures. Progressive transtensional deformation along the two main fault systems was the main mechanism for basin formation and the deposition of thick coarse-grained deposits close to basin-borders. The continuous opening of the basin provided intense intermediate and acid magmatism as well as deposition of volcaniclastic sediments. Event E2 characterizes generalized compression, recorded as minor thrust faults with tectonic transport toward the northwest and left-lateral activation of the NNE-SSW Palmital Shear Zone. Event E3 is related to the Mesozoic tectonism associated with the South Atlantic opening, which generated diabase dykes and predominantly right-lateral strike-slip faults oriented N10-50W. Its rhomboidal geometry with long axis parallel to major Precambrian shear zones, the main presence of high-angle, strike-slip or oblique faults, the asymmetric distribution of geological units and field evidence for concomitant Neoproterozoic magmatism and strike-slip movements are consistent with pull-apart basins reported in the literature.

Data assimilation for the investigation of deep temperature and geothermal energy in the Netherlands.

NASA Astrophysics Data System (ADS)

Bonté, Damien; Limberger, Jon; Lipsey, Lindsey; Cloetingh, Sierd; van Wees, Jan-Diederik

2016-04-01

Deep geothermal energy systems, mostly for the direct use of heat, have been attracting more and more interest in the past 10 years in Western Europe. In the Netherlands, where the sector took off with the first system in 2005, geothermal energy is seen has a key player for a sustainable future. To support the development of deep geothermal energy system, the scientific community has been working on tools that could be used to highlight area of potential interest for geothermal exploration. In the Netherlands, ThermoGIS is one such tool that has been developed to inform the general public, policy makers, and developers in the energy sector of the possibility of geothermal energy development. One major component incorporated in this tool is the temperature model. For the Netherlands, we created a thermal model at the lithospheric scale that focus on the sedimentary deposits for deep geothermal exploration. This regional thermal modelling concentrates on the variations of geological thermal conductivity and heat production both in the sediments and in the crust. In addition, we carried out special modelling in order to specifically understand convectivity in the basin, focusing on variations at a regional scale. These works, as well as recent improved of geological knowledge in the deeper part of the basin, show interesting evidence for geothermal energy development. At this scale, the aim of this work is to build on these models and, using data assimilation, to discriminate in the actual causes of the observed anomalies. The temperature results obtained for the Netherlands show some thermal patterns that relate to the variation of the thermal conductivity and the geometry of the sediments. There is also strong evidence to indicate that deep convective flows are responsible for thermal anomalies. The combination of conductive and local convective thermal patterns makes the deeper part of the Dutch sedimentary basin of great interest for the development of geothermal energy.

Tectonic activity evolution of the Scotia-Antarctic Plate boundary from mass transport deposit analysis

NASA Astrophysics Data System (ADS)

Pérez, Lara F.; Bohoyo, Fernando; Hernández-Molina, F. Javier; Casas, David; Galindo-Zaldívar, Jesús; Ruano, Patricia; Maldonado, Andrés.

2016-04-01

The spatial distribution and temporal occurrence of mass transport deposits (MTDs) in the sedimentary infill of basins and submerged banks near the Scotia-Antarctic plate boundary allowed us to decode the evolution of the tectonic activity of the relevant structures in the region from the Oligocene to present day. The 1020 MTDs identified in the available data set of multichannel seismic reflection profiles in the region are subdivided according to the geographic and chronological distributions of these features. Their spatial distribution reveals a preferential location along the eastern margins of the eastern basins. This reflects local deformation due to the evolution of the Scotia-Antarctic transcurrent plate boundary and the impact of oceanic spreading along the East Scotia Ridge (ESR). The vertical distribution of the MTDs in the sedimentary record evidences intensified regional tectonic deformation from the middle Miocene to Quaternary. Intensified deformation started at about 15 Ma, when the ESR progressively replaces the West Scotia Ridge (WSR) as the main oceanic spreading center in the Scotia Sea. Coevally with the WSR demise at about 6.5 Ma, increased spreading rates of the ESR and numerous MTDs were formed. The high frequency of MTDs during the Pliocene, mainly along the western basins, is also related to greater tectonic activity due to uplift of the Shackleton Fracture Zone by tectonic inversion and extinction of the Antarctic-Phoenix Ridge and involved changes at late Pliocene. The presence of MTDs in the southern Scotia Sea basins is a relevant indicator of the interplay between sedimentary instability and regional tectonics.

Dating the Barremian-Aptian shallow platform deposits at the eastern part of the Kopet Dagh sedimentary basin, NE Iran

NASA Astrophysics Data System (ADS)

Chenarani, Atefeh; Hosseini, Seyedabolfazl; Vahidi Nia, Mohammad

2016-04-01

The Kopet Dagh sedimentary basin covers the northeastern part of Iran, most parts of Turkmenistan and north of Afghanistan which contains several giant gas fields. The extension of this basin in the Iranian part is around 55km2(Afshar Harb, 1994). The Kopet Dagh basin is marked by having very thick sedimentary rocks and lack of volcanic activity. During the Lower Cretaceous, the Tirgan Formation was deposited in a shallow platform setting and lithologically includes in thick-bedded orbitolinid limestones. This study focuses on the biostratigraphy and age determination of these shallow-water deposits using benthic foraminifera and calcareous green algae. In the studied outcrop, the Tirgan Formation has a thickness of 180 m and includes in limestone beds with some marly intervals. It is overlain by the Sarcheshmeh Formation and rests on the Shurijeh Formation. Both contacts are believed to be transitional and lack of discontinuity. A total of 56 thin-sections were used in this study. This study led to determine 28 genera and 14 species of benthic foraminifera along with 13 genera and 5 species of calcareous green algae. Based on the obtained biostratigraphy data, a late Barremian-early Aptian age is suggested for these deposits. We also defined the precise boundary between the Barremian and Aptian which is reported for the first time from this area. Keywords: Barremian-Aptian, Shallow platform, Kopet Dagh, Iran. Reference: Afshar Harb, A., 1994. Geology of Iran: Geology of the Kopet Dagh. Geological survey of Iran, Report No. 11, 275 pp.

The East Falcon Basin: Its Caribbean roots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartok, P.; Boesi, T.

1996-08-01

The East Falcon Basin has been described persistently in the context of the Maracaibo Basin tectonic framework. It is the objective of the present study to demonstrate that the Falcon Basin is, in effect, a Caribbean basin juxtaposed on South America and affected by Caribbean tectonics. The oldest rocks outcropping in the region are Late Paleozoic metamorphic and igneous rocks rafted from northcentral Colombia, Middle Jurassic ophiolite complexes, sediments and metasediments and Cretaceous ophiolites transported by a melange of late Cretaceous to early Tertiary sediments. The south vergence of the Caribbean Nappe province has been documented and extends to themore » present limit of the Andean uplift and to the southern limit of the Coastal Range. The migrating foredeep that developed during the Paleocene-Eocene deposited dominantly basinal shales and thin sandstones. During the Oligocene the Caribbean faults of the Oca system and conjugates began with a dominantly transtensional regime becoming progressively transpressional by Miocene time. The facies development of the Oligocene-Miocene documents the tectonic history. Unique blocks remained as resistant blocks creating ramparts and modifying the basin configuration. During transpression northward-verging thrusting progressively migrated towards the present coastline. The most evident structures of the region are Caribbean in affinity and combined with the sedimentary history of the region can serve to unravel the complex Caribbean-South American plate interaction.« less

The structure of a Mesozoic basin beneath the Lake Tana area, Ethiopia, revealed by magnetotelluric imaging

NASA Astrophysics Data System (ADS)

Hautot, Sophie; Whaler, Kathryn; Gebru, Workneh; Desissa, Mohammednur

2006-03-01

The northwestern Plateau of Ethiopia is almost entirely covered with extensive Tertiary continental flood basalts that mask the underlying formations. Mesozoic and Tertiary sediments are exposed in a few locations surrounding the Lake Tana area suggesting that the Tana depression is an extensional basin buried by the 1-2 km thick Eocene-Oligocene flood basalt sequences in this region. A magnetotelluric survey has been carried out to investigate the deep structure of the Tana area. The objectives were to estimate the thickness of the volcanics and anticipated underlying sedimentary basin. We have collected 27 magnetotelluric soundings south and east of Lake Tana. Two-dimensional inversion of the data along a 160 km long profile gives a model consistent with a NW-SE trending sedimentary basin beneath the lava flows. The thickness of sediments overlying the Precambrian basement averages 1.5-2 km, which is comparable to the Blue Nile stratigraphic section, south of the area. A 1 km thickening of sediments over a 30-40 km wide section suggests that the form of the basin is a half-graben. It is suggested that electrically resistive features in the model are related to volcanic materials intruded within the rift basin sediments through normal faults. The results illustrate the strong control of the Precambrian fracture zones on the feeding of the Tertiary Trap series.

Relationships between sinkholes areal distribution and main tectonic alignments in Abruzzo (Central Italy)

NASA Astrophysics Data System (ADS)

Ferrini, G.; Moretti, A.; De Rose, C.; Stagnini, E.,; Serafini, M.

2012-04-01

Intermountain basins, developed at the back side of the Apennines overturning front, are the most evident morphological expressions of extensional tectonics in Central Italy and can be recognized in many different sections of the chain. L'Aquila basin and the adjoining Subequana valley are part of a single NW-SE elongated depression (about 60 km long) which began to develop about in the early Quaternary in response to the identification of various regional extensional tectonic alignments and the consequent starting of the basin subsidence. This impressive morphological element is characterized by the presence of several large funnel-shaped features (locally named Fosse = trench) which affect mainly the Meso-Cenozoic carbonatic bedrock but also the Neogenic clastic sedimentary filling of the valley. Some of these last elements are often occupied by ponds or significant artesian water resurgences like the Sinizzo Lake where, during L'Aquila earthquake of April 6th 2009, the shores collapsed and strong microseismic activity, deep rumbles and flow rate changes were reported for the following months. The Fosse mapped in the L'Aquila basin have widths in the order of hundreds of meters, a considerable difference of elevation respect the rims and present a general morphology very close to that of the classic dissolution karst sinkholes. Their evolution/localization is strictly related to the active fault systems which controls also the main tracts of the relief; the low volume of residual sedimentary deposits within the depression, not comparable with the total volume of rock removed, indicates that surface karst dissolution phenomena are absent or secondary. The elevations of the floor of many Fosse are higher respect the actual flood plain depending on their age; in fact relict circular forms, recognizable at upper altitude on the relief slope, confirm that the phenomenon has been active for a considerable period of time. About the genesis of this features, even if at present there is no evidence of hydrothermal activity or gas diffusion, morphological and geostructural analogy with the hydrothermal field of San Vittorino (Rieti) suggest dissolution processes related to the rising of underground mineralized fluids (piping) and a subsequent collapse phase, in a classic sink-hole evolutionary model. To note the areal distribution of these elements developed in a narrow band , WNW-ESE oriented, running for about 40 km parallel back to the tectonic front of the Gran Sasso and coinciding, with good approximation, to the seismogenic source of the earthquake of April 6th 2009 and of the major historical earthquakes which hit the region. Geophysical survey carried out after the last strong seismic event pointed out the presence of large hidden cavities developed in the Neogene sedimentary filling of the L'Aquila basin confirming that the phenomenon cannot be considered exhausted; then a geochemical mapping of the all area is started to identify suitable sites for monitoring fluid in relation to seismic activity and to evaluate the risk of potential, sudden phenomena of gravitational collapse.

Facies architecture of a Triassic rift-related Silicic Volcano-Sedimentary succession in the Tethyan realm, Peonias subzone, Vardar (Axios) Zone, northern Greece; Regional implications

NASA Astrophysics Data System (ADS)

Asvesta, Argyro; Dimitriadis, Sarantis

2010-06-01

In northern Greece, along the western edge of the Paleozoic Vertiscos terrane (Serbomacedonian massif) and within the Peonias subzone - the eastern part of the Vardar (Axios) Zone - a Silicic Volcano-Sedimentary (SVS) succession of Permo(?)-Skythian to Mid Triassic age records the development of a faulted continental margin and the formation of rhyolitic volcanoes along a continental shelf fringed by neritic carbonate accumulations. It represents the early rifting extensional stages that eventually led to the opening of the main oceanic basin in the western part of the Vardar (Axios) Zone (the Almopias Oceanic Basin). Even though the SVS succession is deformed, altered, extensively silicified and metamorphosed in the low greenschist facies, primary textures, original contacts and facies relationships are recognized in some places allowing clues for the facies architecture and the depositional environment. Volcanic and sedimentary facies analysis has been carried out at Nea Santa and Kolchida rhyolitic volcanic centres. Pyroclastic facies, mostly composed of gas-supported lapilli tuffs and locally intercalated accretionary lapilli tuffs, built the early cones which were then overridden by rhyolitic aphyric and minor K-feldspar-phyric lava flows. The characteristics of facies, especially the presence of accretionary lapilli, imply subaerial to coastal emplacement at this early stage. The mature and final stages of volcanism are mostly represented by quartz-feldspar porphyry intrusions that probably occupied the vents. At Nea Santa area, the presence of resedimented hyaloclastite facies indicates subaqueous emplacement of rhyolitic lavas and/or lobes. Moreover, quartz-feldspar-phyric sills and a partly extrusive dome featuring peperites at their margins are inferred to have intruded unconsolidated, wet carbonate sediments of the overlying Triassic Neritic Carbonate Formation, in a shallow submarine environment. The dome had probably reached above wave-base as is indicated by the presence of reworked rhyolitic clasts in the younger mixed rhyolite-carbonate epiclastic sedimentary facies. This facies is interpreted as mass- and debris-flow of mixed provenance, deposited below wave-base. The facies architecture of the SVS succession records a change in volcanic activity from explosive to effusive and then to intrusive. The depositional environment changed from subaerial-coastal to shallow submarine as the silicic volcanism evolved and carbonate sedimentation was progressively taking over, probably compensating for the gradual subsidence of the corresponding basin. Silicic magmatism and carbonate sedimentation were contemporaneous and spatially related. The timing of the rifting, the continental crustal elements involved and the accompanying tectonic, magmatic and sedimentary processes are features of the spatially and temporally evolving western peri-Tethyan region.

Recognized Multiple Rifts of the Neoproterozoic in the Initiation of the Tarim Craton (NW China) and Their Tectonic Implications

NASA Astrophysics Data System (ADS)

He, B.; Jiao, C.; Huang, T.; Zhou, X.; Cai, Z.; Cao, Z.; Jiang, Z.; Cui, J.; Yu, Z.; Chen, W.

2017-12-01

The Tarim Basin is the largest, oil-bearing and superimposed basin in the northwest of China. The development and tectonic property of the initial Tarim basin have been acutely disputed and remain enigmatic. Urgently need to reveal the origin and formation dynamics of the Tarim Carton and evaluate the potential of the deep energy resources. However, covered by vast desert and huge-thickness sedimentary strata, suffered by multiple tectonic movements, seismic data with low signal- to- noise ratio in the deep are the critical difficulties. We analyse 4 field outcrops, 18 wells, 27 reprocessed seismic reflection profiles with high SNR across the basin and many ancillary ones and aeromagnetic data. We find about 20 normal fault-controlled rift depressions of the Cryogenian and Ediacaran scattered in the Tarim basin, which developed on the Precambrian metamorphic and crystalline basements and covered by the epeiric sea and basin facies sediments of the Lower Cambrian. The structural styles of the rifts are mainly half grabens, symmetrical troughs and horst-grabens. The regional differences exist obviously in spatial and temporal. The WNW-ESE-trending faults occur in the central part and northern of the basin and the NE, and the NEE-trending faults occur in the southern parts, which response with the anomaly of aeromagnetic. Some main faults of the Ediacaran inherited from the Cryogenian and some occurred newly, the more rifting depressions occurred during the Ediacaran. The extensional NNW-SSE-oriented and NNE-SSW-oriented paleostress field occurred simultaneously during rifting, and accompanied with the clockwise shearing. According to the activities of syn-sedimentary faults, magmatic events and sediments, the tectonic properties of the rifts are different depending on their locations in the Tarim craton. The rifting phases mainly occurred from 780 Ma to 615 Ma. The formation of rifts were associated with the opening of the South Tianshan Ocean and the South Altun-West Kunlun Oceans, which located at the north and south margin of the Tarim block, respectively, in response to break-up of the Rodinia supercontinent. The multiple rifts recognized reflect the fine-scale structure of the initiation of the Tarim craton and is the significant for understanding of the plate system and formation dynamics.

Sedimentary basins reconnaissance using the magnetic Tilt-Depth method

USGS Publications Warehouse

Salem, A.; Williams, S.; Samson, E.; Fairhead, D.; Ravat, D.; Blakely, R.J.

2010-01-01

We compute the depth to the top of magnetic basement using the Tilt-Depth method from the best available magnetic anomaly grids covering the continental USA and Australia. For the USA, the Tilt-Depth estimates were compared with sediment thicknesses based on drilling data and show a correlation of 0.86 between the datasets. If random data were used then the correlation value goes to virtually zero. There is little to no lateral offset of the depth of basinal features although there is a tendency for the Tilt-Depth results to be slightly shallower than the drill depths. We also applied the Tilt-Depth method to a local-scale, relatively high-resolution aeromagnetic survey over the Olympic Peninsula of Washington State. The Tilt-Depth method successfully identified a variety of important tectonic elements known from geological mapping. Of particular interest, the Tilt-Depth method illuminated deep (3km) contacts within the non-magnetic sedimentary core of the Olympic Mountains, where magnetic anomalies are subdued and low in amplitude. For Australia, the Tilt-Depth estimates also give a good correlation with known areas of shallow basement and sedimentary basins. Our estimates of basement depth are not restricted to regional analysis but work equally well at the micro scale (basin scale) with depth estimates agreeing well with drill hole and seismic data. We focus on the eastern Officer Basin as an example of basin scale studies and find a good level of agreement between previously-derived basin models. However, our study potentially reveals depocentres not previously mapped due to the sparse distribution of well data. This example thus shows the potential additional advantage of the method in geological interpretation. The success of this study suggests that the Tilt-Depth method is useful in estimating the depth to crystalline basement when appropriate quality aeromagnetic anomaly data are used (i.e. line spacing on the order of or less than the expected depth to basement). The method is especially valuable as a reconnaissance tool in regions where drillhole or seismic information are either scarce, lacking, or ambiguous.

Thick sequences of silicate and carbonate rocks of sedimentary origin in North America an interim report

USGS Publications Warehouse

Love, John David

1956-01-01

Thick sequences of silicate and carbonate rocks of sedimentary origin have been investigated in 64 areas in North America. The areas containing the thickest and most homogeneous stratigraphic sections more than 1,000 feet thick, buried at depths greater than 10,000 feet are: 1. Uinta Basin, Utah, where the Mancos shale is 1,300 to 5,000 feet thick, the Weber sandstone is 1,000 to 1,600 feet thick, and Mississippian limestones are 1,000 to 1,500 feet thick. 2. Washakie Basin, Wyoming, and Sand Wash Ba.sin, Colorado, where the Lewis shale is 1,000 to 2,000 feet thick and the Cody-Mancos shale is 4,500 to 5,500 feet thick. 3. Green River Basin, Wyoming, where the Cody-Hilliard-Baxter-Mancos shale sequence averages more than 3,000 feet, the siltstone and shale of the Chugwater formation totals 1,000 feet, and the Madison limestone ranges from 1,000 to 1,400 feet thick. 4. Red Desert (Great Divide) Basin, Wyoming, where the Cody shale is 4,000 feet thick. 5. Hanna Basin, Wyoming, where the Steele shale is 4,500 feet thick. 6. Wind River Basin, Wyoming, where the Cody shale is 3,600 to 5,000 feet thick. Geochemical characteristics of these rocks in these areas are poorly known but are being investigated. A summary of the most pertinent recent ana1yses is presented.

Tectonic controls on rift basin morphology: Evolution of the northern Malawi (Nyasa) rift

NASA Technical Reports Server (NTRS)

Ebinger, C. J.; Deino, A. L.; Tesha, A. L.; Becker, T.; Ring, U.

1993-01-01

Radiometric (K-Ar and Ar-40/Ar-39) age determinations of volcanic and volcaniclastic rocks, combined with structural, gravity, and seismic reflection data, are used to constrain the age of sedimentary strata contained within the seismically and volcanically active northern Malawi (Nyasa) rift and to characterize changes in basin and flank morphologies with time. Faulting and volcanism within the Tukuyu-Karonga basin began at approximately 8.6 Ma, when sediments were deposited in abroad, initially asymmetric lake basin bounded on its northeastern side by a border fault system with minor topographic relief. Extensions, primarily by a slip along the border fault, and subsequent regional isostatic compensation led to the development of a 5-km-deep basin bounded by broad uplifted flanks. Along the low-relief basin margin opposite border fault, younger stratigraphic sequences commonly onlap older wedge-shaped sequences, although their internal geometry is often progradational. Intrabasinal faulting, flankuplift, and basaltic and felsic volcanism from centers at the northern end of the basin became more important at about 2.5 Ma when cross-rift transfer faults developed to link the Tukuyu-Karonga basin to the Rukwa basin. Local uplift and volcanic construction at the northern end of the basin led to a southeastward shift in the basin's depocenter. Sequence boundaries are commonly erosional along this low-relief (hanging wall) margin and conformable in the deep lake basin. The geometry of stratigraphic sequences and the distribution of the erosion indicate that horizontal and vertical crustal movements both across and along the length of the rift basin led to changes in levels of the lake, irrespective of paleoclimatic fluctuations.

New oil and gas province of Russia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gramberg, I.S.; Shcola, A.I.

1994-12-31

Geological and geophysical researches and exploration works conducted in the Russian Arctic offshore during the last two decades indicate the presence of extensive sedimentary basins. The data coverage in this vast continental margin is uneven, and the reliability of hydrocarbon prediction varies significantly from one basin to the next. Nevertheless, the existence of a major frontier Barents-Northern Kara Oil and Gas Province (BNKP) is quite evident. The BNKP encompasses the Barents Sea and the Northern Kara Sea subbottom, the islands along the shelf edge, the Kola Peninsula shelf, the Arkhangelsk coastal territory, and a large part of the northernmost Komimore » Republic. The total area of BNKP is close to 1,500,000 sq. km, and the sediments in the deepest depocenter (South Barents Basin) reach 16--18 km. Vast areal extent, great thickness of sedimentary cover, favorable conditions for oil and gas generation and accumulation, presence of oil and gas fields in all major sequences suggest a very high hydrocarbon potential for the BNKP.« less

Analysis of the Source System of Nantun Group in Huhehu Depression of Hailar Basin

NASA Astrophysics Data System (ADS)

Li, Yue; Li, Junhui; Wang, Qi; Lv, Bingyang; Zhang, Guannan

2017-10-01

Huhehu Depression will be the new battlefield in Hailar Basin in the future, while at present it’s in a low exploration level. The study about the source system of Nantun group is little, so fine depiction of the source system would be significant to sedimentary system reconstruction, the reservoir distribution and prediction of favorable area. In this paper, it comprehensive uses of many methods such as ancient landform, light and heavy mineral combination, seismic reflection characteristics, to do detailed study about the source system of Nantun group in different views and different levels. The results show that the source system in Huhehu Depression is from the east of Xilinbeir bulge and the west of Bayan Moutain uplift, which is surrounded by basin. The slope belt is the main source, and the southern bulge is the secondary source. The distribution of source system determines the distribution of sedimentary system and the regularity of the distribution of sand body.

TDEM survey in an area of seismicity induced by water wells in Paraná sedimentary basin, Northern São Paulo State, Brazil

NASA Astrophysics Data System (ADS)

Porsani, Jorge Luís; Almeida, Emerson Rodrigo; Bortolozo, Cassiano Antonio; Santos, Fernando Acácio Monteiro dos

2012-07-01

This article presents TDEM results from an area with recent induced shallow seismicity. The purpose was to do a geoelectrical mapping of sedimentary and fractured basaltic aquifers for better understanding of the hydrogeologic setting. The study area is in the Paraná basin where flood basalts are overlain by sedimentary units near the city of Bebedouro, northern São Paulo State, Brazil. 86 TDEM soundings were acquired in an area of 90 km2 in the Andes and Botafogo study areas. The soundings were chosen next to wells for calibration, and also along profiles crossing the seismically active areas. 1-D interpretation results showed the general geoelectrical stratigraphy of this part of the Paraná basin. The upper geoelectrical layer is the shallow sedimentary aquifer (Adamantina formation) with less than 80 m thickness. The second geoelectrical layer contains the upper basalts of the Serra Geral formation at about 60-80 m depths. A saturated fractured basalt zone between 100 and 300 m depths was identifiable on various TDEM soundings. This depth range corresponds to the range of hypocentral depths for more than 3000 micro-earthquakes in this area. The lower basalt layer was estimated to lie between 400 and 650 m depth. The deepest geoelectrical layer detected by various TDEM soundings corresponds to the Botucatu sandstone (Guarani aquifer). Results suggest that the high-discharge wells are located in the fractured zone in the middle basalt of the Serra Geral formation. There is a good correlation between seismically active areas, high discharge wells (> 190 m3/h), and fracture zones in the middle basalt. The results reinforce the hypothesis that the shallow seismic activity in the Bebedouro region is being triggered by high rates of groundwater withdrawal.

Sedimentary response to orogenic exhumation in the northern rocky mountain basin and range province, flint creek basin, west-central Montana

USGS Publications Warehouse

Portner, R.A.; Hendrix, M.S.; Stalker, J.C.; Miggins, D.P.; Sheriff, S.D.

2011-01-01

Middle Eocene through Upper Miocene sedimentary and volcanic rocks of the Flint Creek basin in western Montana accumulated during a period of significant paleoclimatic change and extension across the northern Rocky Mountain Basin and Range province. Gravity modelling, borehole data, and geologic mapping from the Flint Creek basin indicate that subsidence was focused along an extensionally reactivated Sevier thrust fault, which accommodated up to 800 m of basin fill while relaying stress between the dextral transtensional Lewis and Clark lineament to the north and the Anaconda core complex to the south. Northwesterly paleocurrent indicators, foliated metamorphic lithics, 64 Ma (40Ar/39Ar) muscovite grains, and 76 Ma (U-Pb) zircons in a ca. 27 Ma arkosic sandstone are consistent with Oligocene exhumation and erosion of the Anaconda core complex. The core complex and volcanic and magmatic rocks in its hangingwall created an important drainage divide during the Paleogene shedding detritus to the NNW and ESE. Following a major period of Early Miocene tectonism and erosion, regional drainage networks were reorganized such that paleoflow in the Flint Creek basin flowed east into an internally drained saline lake system. Renewed tectonism during Middle to Late Miocene time reestablished a west-directed drainage that is recorded by fluvial strata within a Late Miocene paleovalley. These tectonic reorganizations and associated drainage divide explain observed discrepancies in provenance studies across the province. Regional correlation of unconformities and lithofacies mapping in the Flint Creek basin suggest that localized tectonism and relative base level fluctuations controlled lithostratigraphic architecture.

Tectonic and climatic control on evolution of rift lakes in the Central Kenya Rift, East Africa

NASA Astrophysics Data System (ADS)

Bergner, A. G. N.; Strecker, M. R.; Trauth, M. H.; Deino, A.; Gasse, F.; Blisniuk, P.; Dühnforth, M.

2009-12-01

The long-term histories of the neighboring Nakuru-Elmenteita and Naivasha lake basins in the Central Kenya Rift illustrate the relative importance of tectonic versus climatic effects on rift-lake evolution and the formation of disparate sedimentary environments. Although modern climate conditions in the Central Kenya Rift are very similar for these basins, hydrology and hydrochemistry of present-day lakes Nakuru, Elmenteita and Naivasha contrast dramatically due to tectonically controlled differences in basin geometries, catchment size, and fluvial processes. In this study, we use eighteen 14C and 40Ar/ 39Ar dated fluvio-lacustrine sedimentary sections to unravel the spatiotemporal evolution of the lake basins in response to tectonic and climatic influences. We reconstruct paleoclimatic and ecological trends recorded in these basins based on fossil diatom assemblages and geologic field mapping. Our study shows a tendency towards increasing alkalinity and shrinkage of water bodies in both lake basins during the last million years. Ongoing volcano-tectonic segmentation of the lake basins, as well as reorganization of upstream drainage networks have led to contrasting hydrologic regimes with adjacent alkaline and freshwater conditions. During extreme wet periods in the past, such as during the early Holocene climate optimum, lake levels were high and all basins evolved toward freshwater systems. During drier periods some of these lakes revert back to alkaline conditions, while others maintain freshwater characteristics. Our results have important implications for the use and interpretation of lake sediment as climate archives in tectonically active regions and emphasize the need to deconvolve lacustrine records with respect to tectonics versus climatic forcing mechanisms.

Processing of thermal parameters for the assessment of geothermal potential of sedimentary basins

NASA Astrophysics Data System (ADS)

Pasquale, V.; Chiozzi, P.; Gola, G.; Verdoya, M.

2009-04-01

The growing interest on renewable energy sources is stimulating new efforts aimed at the assessment of geothermal potential in several countries, and new developments are expected in the near future. In this framework, a basic step forward is to focus geothermal investigations on geological environments which so far have been relatively neglected. Some intracontinental sedimentary basins could reveal important low enthalpy resources. The evaluation of the geothermal potential in such geological contexts involves the synergic use of geophysical and hydrogeological methodologies. In sedimentary basins a large amount of thermal and hydraulic data is generally available from petroleum wells. Unfortunately, borehole temperature data are often affected by a number of perturbations which make very difficult determination of the true geothermal gradient. In this paper we addressed the importance of the acquisition of thermal parameters (temperature, geothermal gradient, thermal properties of the rock) and the technical processing which is necessary to obtain reliable geothermal characterizations. In particular, techniques for corrections of bottom-hole temperature (BHT) data were reviewed. The objective was to create a working formula usable for computing the undisturbed formation temperature for specific sedimentary basins. As test areas, we analysed the sedimentary basins of northern Italy. Two classical techniques for processing temperature data from oil wells are customarily used: (i) the method by Horner, that requires two or more measurements of bottom-hole temperatures carried out at the same depth but at different shut-in times te and (ii) the technique by Cooper and Jones, in which several physical parameters of the mud and formation need to be known. We applied both methods to data from a number of petroleum explorative wells located in two areas of the Po Plain (Apenninic buried arc and South Piedmont Basin - Pedealpine homocline). From a set of about 40 wells having two or more temperature measurements at a single depth we selected 18 wells with BHTs recorded at te larger than 3.5 hours; the time span between two measurements varies from 1 to 21 hours. In total 71 couples of BHT-te data are available; the mud circulation time is lower or equal to 4.5 hours. Corrections require the knowledge of thermal parameters. We attempted to remedy the existing deficiency of thermal conductivity data of sedimentary rocks with a series of laboratory measurements on several core samples recovered from wells. Moreover, we developed a model for calculating the thermal conductivity of the rock matrix as a function of mineral composition based on the fabric theory and experimental thermal conductivity data. As the conductivity of clay minerals, which are present in most formations, is poorly defined, we applied an inverse approach, in which mineral conductivities are calculated one by one, on condition that the sample bulk thermal conductivity, the porosity and the amount of each mineral phase are known. Analyses show that formation equilibrium temperatures computed with the Horner method are consistent with those obtained by means of the Cooper and Jones method, which gives on average temperatures lower than 2 C only for shut-in times < 10 hours. The corrected temperatures compared with temperatures measured during drill-stem tests show that the proposed corrections are rather accurate. The two data sets give coherent results and the inferred average geothermal gradient is 21.5 mK/m in the Apenninic buried arc area and 25.2 mK/m in the South Piedmont Basin-Pedealpine homocline area. The problem with the Horner method is that it implicitly assumes no physical property contrast between circulating mud and formation, and that the borehole is infinitesimally thin, i.e. it acts as a line source. This has been criticized by many authors. The accuracy of the predicted temperatures depends on the reliability and accuracy of BHT, shut-in time and mud circulation time, and the error increases with the decrease of the shut-in time. On the other hand, the method by Cooper and Jones provides more reliable results, but requires physical parameters that are not always available. The Horner slope data as a function of depth were then fitted with a second order polynomial and depth-time correction equations were calibrated for the two test areas. The obtained depth-time correction equations allow for each area the correction for mud circulation when only one couple BHT-te is available. If the value of the time before circulation ceased is not included on the well log header, it is possible to formulate an empirical equation obtained from time data as a function of depth applicable to the whole investigated area.

Mesozoic evolution of the Amu Darya basin

NASA Astrophysics Data System (ADS)

Brunet, Marie-Françoise; Ershov, Andrey; Korotaev, Maxim; Mordvintsev, Dmitriy; Barrier, Eric; Sidorova, Irina

2014-05-01

This study, granted by the Darius Programme, aims at proposing a model of tectono-stratigraphic evolution of the Amu Darya basin since the Late Palaeozoic and to understand the relationship with the nearby basins. The Amu Darya basin, as its close eastern neighbour, the Afghan-Tajik basin, lies on the Turan platform, after the closure of the Turkestan Ocean during the Late Paleozoic. These two basins, spread on mainly lowlands of Turkmenistan, southwest Uzbekistan, Tajikistan, and northern Afghanistan, are separated from one another by the South-Western Gissar meganticline, where series of the northern Amu Darya margin are outcropping. The evolution is closely controlled by several periods of crustal thinning (post-collision rifting and back-arc extension), with some marine incursions, coming in between accretions of continental blocks and collisions that succeeded from the Late Triassic-Early Jurassic (Eo-Cimmerian orogeny) to the Cenozoic times. These orogenies controlled the deposition of thick clastics sequences, and the collision of the Indian Plate with Eurasia strongly deformed the sedimentary cover of the Afghan-Tajik basin. The more than 7 km thick Meso-Cenozoic sedimentary succession of the Amu Darya basin, lies on a complex system of rifts and blocks. Their orientation and age (late Permian, Triassic?) are not well known because of deep burial. The north-eastern margin, with the Bukhara (upper margin) and Chardzhou steps, is NW oriented, parallel to the Paleozoic Turkestan suture. The orientation bends to W-E, in the part of the Gissar situated to the North of the Afghan-Tajik basin. This EW trending orientation prevails also in the south(-eastern) margin of the basin (series of North Afghanistan highs) and in the Murgab depression, the south-eastern deepest portion of the Amu Darya basin. It is in this area and in the eastern part of the Amu Darya basin that the Jurassic as well as the lower Cretaceous sediments are the thickest. The south-western part of the basin is occupied by the Pre-Kopet Dagh Cenozoic foreland basin NW oriented, possibly underlain by an earlier extensional trough. The main elements of the sedimentary pile, which can be partly observed in the South-Western Gissar are: Lower to Middle Jurassic continental to paralic clastic rocks; upper Middle to Upper Jurassic marine carbonate then thick Tithonian evaporite rocks, sealing the reservoirs in the Jurassic carbonates; continental Neocomian clastic rocks and red beds, Aptian to Paleogene marine carbonate and clastic rocks. To reconstruct the geodynamic evolution of the Amu Darya Basin, we analysed the subsidence by backstripping of some wells/pseudo-wells and of three cross-sections with some examples of thermal modelling on the periods of maturation of the potential source rocks. The crustal thinning events take place in the Permo-Triassic? (depending on the age of the rifts underlying the basin), in Early-Middle Jurassic and during the Early Cretaceous, resulting in increases of the tectonic subsidence rates.

Sediment storage quantification and postglacial evolution of an inner-alpine sedimentary basin (Gradenmoos, Schober Mountains, Austria)

NASA Astrophysics Data System (ADS)

Götz, J.; Buckel, J.; Otto, J. C.; Schrott, L.

2012-04-01

Knickpoints in longitudinal valley profiles of alpine headwater catchments can be frequently assigned to the lithological and tectonical setting, to damming effects through large (rockfall) deposits, or to the impact of Pleistocene glaciations causing overdeepened basins. As a consequence various sedimentary sinks developed, which frequently interrupt sediment flux in alpine drainage basins. Today these locations may represent landscape archives documenting a sedimentary history of great value for the understanding of alpine landscape evolution. The glacially overdeepened Gradenmoos basin at 1920 m a.s.l. (an alpine lake mire with adjacent floodplain deposits and surrounding slope storage landforms; approx. 4.1 km2) is the most pronounced sink in the studied Gradenbach catchment (32.5 km2). The basin is completely filled up with sediments delivered by mainly fluvial processes, debris flows, and rock falls, it is assumed to be deglaciated since Egesen times and it is expected to archive a continuous stratigraphy of postglacial sedimentation. As the analysis of denudation-accumulation-systems is generally based on back-calculation of stored sediment volumes to a specific sediment delivering area, most reliable results will be consequently obtained (1) if sediment output of the system can be neglected for the investigated period of time, (2) if - due to spatial scale - sediment storage can be assessed quantitatively with a high level of accuracy, and (3) if the sediment contributing area can be clearly delimited. All three aspects are considered to be fulfilled to a high degree within the Gradenmoos basin. Sediment storage is quantified using geophysical methods, core drillings and GIS modelling whereas postglacial reconstruction is based on radiocarbon dating and palynological analyses. Subject to variable subsurface conditions, different geophysical methods were applied to detect bedrock depth. Electrical resistivity surveying (2D/3D) was used most extensively as it delivered detailed and realistic subsurface models with low residual errors in the fine grained and water saturated central and distal part of the basin. With a lower data density, ground penetrating radar and refraction seismic supplied bedrock depths underneath adjacent debris and talus slope deposits. Additionally extracted sediment cores (up to 22 m depth) yielded a detailed stratigraphic record of the basin comprising a basal till layer underneath lake sediments (sandy-silty, partly varved), a sandy matrix with several oxidised layers in the upper sections, and layers of peat towards the surface. As bedrock was reached several times, core drilling further enabled to calibrate resistivity models. On the base of geophysical derived bedrock points, the shape of the assumed bedrock basin was modelled using a thin-plate-spline interpolation. Sediment volumes were calculated by subtracting the bedrock model from a surface DEM derived from terrestrial laser scanning. Since sediment delivering areas can be clearly assigned to single storage landform volumes, denudation rates could be calculated in detail and related to sedimentation rates obtained by radiocarbon dating results. An integrated analysis of surface, subsurface and temporal information finally yielded a model of postglacial basin evolution which will be discussed in a paraglacial context. This presentation is supported by the EUROCORES programme TOPO-EUROPE of the European Science Foundation.

Petrography and the REE-composition of apatite in the Paleoproterozoic Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia

NASA Astrophysics Data System (ADS)

Joosu, Lauri; Lepland, Aivo; Kreitsmann, Timmu; Üpraus, Kärt; Roberts, Nick M. W.; Paiste, Päärn; Martin, Adam P.; Kirsimäe, Kalle

2016-08-01

The first globally significant phosphorous-rich deposits appear in the Paleoproterozoic at around 2 Ga, however, the specific triggers leading to apatite precipitation are debated. We examine phosphorous-rich rocks (up to 8 wt% P2O5) in 1.98-1.92 Ga old Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia. Phosphates in these rocks occur as locally derived and resedimented sand-to-gravel/pebble sized grains consisting of apatite-cemented muddy sediments. Phosphatic grains can be subdivided into four petrographic types (A-D), each has a distinct REE signature reflecting different early-to-late diagenetic conditions and/or metamorphic overprint. Pyrite containing petrographic type D, which typically has a flat REE pattern, negative Ce anomaly and positive Eu anomaly, is the best preserved of the four types and best records conditions present during apatite precipitation. Type D phosphatic grains precipitated under (sub)oxic basinal conditions with a significant hydrothermal influence. These characteristics are similar to Zaonega Formation phosphates of NW Russia's Onega Basin, and consistent with phosphogenesis triggered by the development of anoxic(sulfidic)-(sub)oxic redoxclines at shallow sediment depth during the Paleoproterozoic.

Full 40 km crustal reflection seismic datasets in several Indonesian basins

NASA Astrophysics Data System (ADS)

Dinkelman, M. G.; Granath, J. W.; Christ, J. M.; Emmet, P. A.; Bird, D. E.

2010-12-01

Long offset, deep penetration regional 2D seismic data sets have been acquired since 2002 by GX Technology in a number of regions worldwide (www.iongeo.com/Data_Libraries/Spans/). Typical surveys consist of 10+ lines located to image specific critical aspects of basin structure. Early surveys were processed to 20 km, but more recent ones have extended to 40-45 km from 16 sec records. Pre-stack time migration is followed by pre-stack depth migration using gravity and in some cases magnetic modeling to constrain the velocity structure. We illustrate several cases in the SE Asian and Australasian area. In NatunaSPAN™ two generations of inversion can be distinguished, one involving Paleogene faults with Neogene inversion and one involving strike slip-related uplift in the West Natuna Basin. Crustal structure in the very deep Neogene East Natuna Basin has also been imaged. The JavaSPAN™ program traced Paleogene sediments onto oceanic crust of the Flores Sea, thus equating back arc spreading there to the widespread Eocene extension. It also imaged basement in the Makassar Strait beneath as much as 6 km of Cenozoic sedimentary rocks that accumulated Eocene rift basins (the North and South Makassar basins) on the edge of Sundaland, the core of SE Asia. The basement is seismically layered: a noisy upper crust overlies a prominent 10 km thick transparent zone, the base of which marks another change to slightly noisier reflectivity. Eocene normal faults responsible for the opening of extensional basins root in the top of the transparent layer which may be Moho or a brittle-ductile transition within the extended continental crust. Of particular significance is the first image of thick Precambrian basins comprising the bulk of continental crust under the Arafura Sea in the ArafuraSPAN™ program. Four lines some 1200 km long located between Australia and New Guinea on the Arafura platform image a thin Phanerozoic section overlying a striking Precambrian basement composed of sedimentary and burial metamorphosed sedimentary rock that we divide into two packages on the basis of seismic character. The upper is 8-15 km of undeformed late Precambrian sediments the top of which ties Eocambrian rocks in wells in offshore New Guinea. This package appears to correlate to the Wessel Group in northern Australia. The lower package is composed of 10-15 km of strongly bedded, presumably burial metamorphosed rocks that make up the bulk of the lower crust. These may equate to any of a number of northern Australian Mesoproterozoic basins. This lower package offlaps ‘pods’ of seismically transparent basement (?Paleoproterozoic or Archean) that make up at most the lowermost 15 km of the 40 km PSDM line. Both Precambrian packages appear to be craton-margin sedimentary wedges, the younger overlapping the older. The SE extent of the lowermost package is deformed in a thrust system which may mark the event that detached it from its original underlying oceanic or transitional crust during cratonization. The SPAN programs are important new data sets to clarify and in some cases solve outstanding problems in basin architecture and tectonic evolution.

Hydrocarbon provinces and productive trends in Libya and adjacent areas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Missallati, A.A.

1988-08-01

According to the age of major reservoirs, hydrocarbon occurrences in Libya and adjacent areas can be grouped into six major systems which, according to their geographic locations, can be classified into two major hydrocarbon provinces: (1) Sirte-Pelagian basins province, with major reservoirs ranging from middle-late Mesozoic to early Tertiary, and (2) Murzog-Ghadames basins province, with major reservoirs ranging from early Paleozoic to early Mesozoic. In the Sirte-Pelagian basins province, hydrocarbons have been trapped in structural highs or in stratigraphic wedge-out against structural highs and in carbonate buildups. Here, hydrocarbon generation is characterized by the combined effect of abundant structural reliefmore » and reservoir development in the same hydrocarbon systems of the same age, providing an excellent example of hydrocarbon traps in sedimentary basins that have undergone extensive tensional fracturing in a shallow marine environment. In the Murzog-Ghadames basins province, hydrocarbons have been trapped mainly in structural highs controlled by paleostructural trends as basement arches which acted as focal points for oil migration and accumulation.« less

The Efficacy and Potential of Renewable Energy from Carbon Dioxide that is Sequestered in Sedimentary Basin Geothermal Resources

NASA Astrophysics Data System (ADS)

Bielicki, J. M.; Adams, B. M.; Choi, H.; Saar, M. O.; Taff, S. J.; Jamiyansuren, B.; Buscheck, T. A.; Ogland-Hand, J.

2015-12-01

Mitigating climate change requires increasing the amount of electricity that is generated from renewable energy technologies and while simultaneously reducing the amount of carbon dioxide (CO2) that is emitted to the atmosphere from present energy and industrial facilities. We investigated the efficacy of generating electricity using renewable geothermal heat that is extracted by CO2 that is sequestered in sedimentary basins. To determine the efficacy of CO2-Geothermal power production in the United States, we conducted a geospatial resource assessment of the combination of subsurface CO2 storage capacity and heat flow in sedimentary basins and developed an integrated systems model that combines reservoir modeling with power plant modeling and economic costs. The geospatial resource assessment estimates the potential resource base for CO2-Geothermal power plants, and the integrated systems model estimates the physical (e.g., net power) and economic (e.g., levelized cost of electricity, capital cost) performance of an individual CO2-Geothermal power plant for a range of reservoir characteristics (permeability, depth, geothermal temperature gradient). Using coupled inverted five-spot injection patterns that are common in CO2-enhanced oil recovery operations, we determined the well pattern size that best leveraged physical and economic economies of scale for the integrated system. Our results indicate that CO2-Geothermal plants can be cost-effectively deployed in a much larger region of the United States than typical approaches to geothermal electricity production. These cost-effective CO2-Geothermal electricity facilities can also be capacity-competitive with many existing baseload and renewable energy technologies over a range of reservoir parameters. For example, our results suggest that, given the right combination of reservoir parameters, LCOEs can be as low as $25/MWh and capacities can be as high as a few hundred MW.

Feast to famine: Sediment supply control on Laramide basin fill

NASA Astrophysics Data System (ADS)

Carroll, Alan R.; Chetel, Lauren M.; Elliot Smith, M.

2006-03-01

Erosion of Laramide-style uplifts in the western United States exerted an important first-order influence on Paleogene sedimentation by controlling sediment supply rates to adjacent closed basins. During the latest Cretaceous through Paleocene, these uplifts exposed thick intervals of mud-rich Upper Cretaceous foreland basin fill, which was quickly eroded and redeposited. Cretaceous sedimentary lithologies dominate Paleocene conglomerate clast compositions, and the volume of eroded foreland basin strata is approximately twice the volume of preserved Paleocene basin fill. As a result of this sediment oversupply, clastic alluvial and paludal facies dominate Paleocene strata, and are associated with relatively shallow and ephemeral freshwater lake facies. In contrast, large, long-lived, carbonate-producing lakes occupied several of the basins during the Eocene. Basement-derived clasts (granite, quartzite, and other metamorphic rocks) simultaneously became abundant in lower Eocene conglomerate. We propose that Eocene lakes developed primarily due to exposure of erosion-resistant lithologies within cores of Laramide uplifts. The resultant decrease in erosion rate starved adjacent basins of sediment, allowing the widespread and prolonged deposition of organic-rich lacustrine mudstone. These observations suggest that geomorphic evolution of the surrounding landscape should be considered as a potentially important influence on sedimentation in many other interior basins, in addition to more conventionally interpreted tectonic and climatic controls.

Regional fluid flow as a factor in the thermal history of the Illinois basin: Constraints from fluid inclusions and the maturity of Pennsylvanian coals

USGS Publications Warehouse

Rowan, E.L.; Goldhaber, M.B.; Hatch, J.R.

2002-01-01

Vitrinite reflectance measurements on Pennsylvanian coals in the Illinois basin indicate significantly higher thermal maturity than can be explained by present-day burial depths. An interval of additional sedimentary section, now removed by erosion, has been suggested to account for the discrepancy. Although burial could indeed account for the observed maturity levels of organic matter, fluid-inclusion temperatures provide a stringent additional constraint. In this article, we combine measurements of coal maturity with fluid-inclusion temperatures from three sites to constrain the basin's thermal and burial history: the Fluorspar district at the Illinois basin's southern margin, the Upper Mississippi Valley zinc district at the basin's northern margin, and a north-central location. Two-dimensional numerical modeling of a north-south cross section through the basin tests scenarios both with and without regional fluid flow. Vitrinite reflectance values can be matched assuming burial by 1.8-2.8 km of southward-thickening additional, post-Pennsylvanian sedimentary section. In the central and northern Illinois basin, however, these burial depths and temperatures are not sufficient to account for the fluid-inclusion data. To account for both parameters with burial alone does not appear feasible. In contrast, our best hypothesis assumes a wedge of post-Pennsylvanian sediment-thickening southward to about 1.2 km and a brief period of magmatism in the Fluorspar district. Significant advective heat redistribution by northward regional fluid flow accounts for fluid-inclusion temperatures and coal maturities throughout the basin. The modeling results demonstrate the potential contribution of advective heat transport to the thermal history of the Illinois basin.

Natural gas accumulations in low-permeability Tertiary, and Cretaceous (Campanian and Maastrichtian) rock, Uinta Basin, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fouch, T.D.; Wandrey, C.J.; Pitman, J.K.

1992-02-01

This report characterizes Upper Cretaceous Campanian and Maastrichtian, and lower Tertiary gas-bearing rocks in the Uinta Basin with special emphasis on those units that contain gas in reservoirs that have been described as being tight. The report was prepared for the USDOE whose Western Tight Gas Sandstone Program cofunded much of this research in conjunction with the US Geological Survey's Evolution of Sedimentary Basins, and Onshore Oil and Gas Programs. (VC)

Natural gas accumulations in low-permeability Tertiary, and Cretaceous (Campanian and Maastrichtian) rock, Uinta Basin, Utah. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fouch, T.D.; Wandrey, C.J.; Pitman, J.K.

1992-02-01

This report characterizes Upper Cretaceous Campanian and Maastrichtian, and lower Tertiary gas-bearing rocks in the Uinta Basin with special emphasis on those units that contain gas in reservoirs that have been described as being tight. The report was prepared for the USDOE whose Western Tight Gas Sandstone Program cofunded much of this research in conjunction with the US Geological Survey`s Evolution of Sedimentary Basins, and Onshore Oil and Gas Programs. (VC)

The Valley and Ridge Province of eastern Pennsylvania - stratigraphic and sedimentologic contributions and problems ( USA).

USGS Publications Warehouse

Epstein, J.B.

1986-01-01

The rocks in the area, which range from Middle Ordovician to Late Devonian in age, are more than 7620 m thick. This diversified group of sedimentary rocks was deposited in many different environments, ranging from deep sea, through neritic and tidal, to alluvial. In general, the Middle Ordovician through Lower Devonian strata are a sedimentary cycle related to the waxing and waning of Taconic tectonism. The sequence began with a greywacke-argillite suite (Martinsburg Formation) representing synorogenic basin deepening. This was followed by basin filling and progradation of a sandstone-shale clastic wedge (Shawangunk Formation and Bloomsburg Red Beds) derived from the erosion of the mountains that were uplifted during the Taconic orogeny. The sequence ended with deposition of many thin units of carbonate, sandstone, and shale on a shelf marginal to a land area of low relief. Another tectonic-sedimentary cycle, related to the Acadian orogeny, began with deposition of Middle Devonian rocks. Deep-water shales (Marcellus Shale) preceded shoaling (Mahantango Formation) and turbidite sedimentation (Trimmers Rock Formation) followed by another molasse (Catskill Formation). -from Author

Contextualising impacts of logging on tropical rainforest catchment sediment dynamics using the stratigraphic record of in-channel bench deposits

NASA Astrophysics Data System (ADS)

Blake, Will; Walsh, Rory; Bidin, Kawi; Annammala, Kogila

2015-04-01

It is widely recognised that commercial logging and conversion of tropical rainforest to oil palm plantation leads to enhanced fluvial sediment flux to the coastal zone but the dynamics of delivery and mechanisms that act to retain sediment and nutrients within rainforest ecosystems, e.g. riparian zone and floodplain storage, are poorly understood and underexploited as a management tool. While accretion of lateral in-channel bench deposits in response to forest clearance has been demonstrated in temperate landscapes, their development and value as sedimentary archives of catchment response to human disturbance remains largely unexplored in tropical rainforest river systems. Working within the Segama River basin, Sabah, Malaysian Borneo, this study aimed to test the hypothesis that (1) lateral bench development in tropical rainforest rivers systems is enhanced by upstream catchment disturbance and that (2) the sedimentary record of these deposits can be used to infer changes in sediment provenance and intensification of sediment flux associated with logging activities. Sediment cores were taken from in-channel bench deposits with upstream catchment contributing areas of 721 km2 and 2800 km2 respectively. Accretion rates were determined using fallout 210Pb and 137Cs and the timing of peak accumulation was shown to correspond exactly with the known temporal pattern of logging and associated fluvial sediment response over the period 1980 to present following low pre-logging rates. Major and minor element geochemistry of deposits was used to assess the degree of weathering that deposited sediment had experienced. This was linked to surface (heavily weathered) and subsurface (less weathered) sediment sources relating to initial disturbance by logging and post-logging landsliding responses respectively. A shift in the dominant source of deposited material from surface (i.e. topsoil) to subsurface (i.e. relatively unweathered subsoil close to bedrock) origin was observed to coincide with the increase in accretion rates following logging of steep headwater slopes. Coherence of sedimentary, monitoring and observational evidence demonstrates that in-channel bench deposits offer a previously unexplored sedimentary archive of catchment response to logging in tropical rainforest systems and a tool for evaluating the erosional responses of ungauged basins. In-channel bench development due to catchment disturbance may augment ecosystem services provided by the riparian corridors of larger rivers and process knowledge gained from sedimentary archives can be used to underpin future riparian and catchment forest management strategies.

Aeromagnetic maps of the Uinta and Piceance Basins and vicinity, Utah and Colorado

USGS Publications Warehouse

Grauch, V.J.S.; Plesha, Joseph L.

1989-01-01

In order to understand the evolution of sedimentary basins, it is important to understand their tectonic setting. In a U.S. Geological Survey (USGS) study of the Uinta and Piceance basins in Utah and Colorado, this understanding is approached through characterization of subsurface structure and lithology of a large region encompassing the basins. An important tool for interpreting these subsurface features is aeromagnetic data. Aeromagnetic anomalies represent variations in the strength and direction of the Earth's magnetic field that are produced by rocks containing a significant number of magnetic minerals (commonly magnetite). The shape and magnitude of an anomaly produced by one body of rock are complexly related to the amount of magnetic minerals present, the magnetic properties of those minerals (determined by a number of factors, including the history of the rock), and the shape of the rock body. In the study area, only crystalline basement rocks and volcanic rocks are likely to contain enough magnetic minerals to produce anomalies; sedimentary rocks and metasediments are generally so poor in magnetic minerals that their magnetic effects cannot be detected by the types of surveys presented in this report. Patterns of anomalies on aeromagnetic maps can reveal not only lithologic differences related to magnetite content, but structural features as well, such as faults that have juxtaposed crystalline rocks against sedimentary rocks, and upwarps of crystalline basement underlying sedimentary sequences. Tectonic features of regional extent may not become apparent until a number of aeromagnetic surveys have been compiled and plotted at the same scale. Commonly the compilation involves piecing together data from surveys that were flown at different times and have widely disparate flight specifications and data reduction procedures. The data may be compiled into a composite map, where all the pieces are plotted onto one map without regard to the differences in flight elevation and datum, or they may be compiled into a merged map, where all survey data are analytically reduced to a common flight elevation and datum, and then digitally merged at the survey boundaries. The composite map retains the original resolution of all survey data, but computer methods to enhance or model regional features crossing the survey boundaries cannot be applied. On the other hand, these computer methods can be applied to the merged data, but the resolution of the data may be somewhat diminished. This report presents both composite and merged aeromagnetic maps for a large region that includes the Uinta Basin in Utah and the Piceance basin in Colorado (fig. 1).

Effects of livestock grazing on nutrient retention in a headwater stream of the Rio Puerco Basin

Treesearch

Mark A. Sewards; H. Maurice Valett

1996-01-01

Sediment and nutrient loss from headwater streams of sedimentary basins in the semi-arid Southwest have been attributed to both over-grazing by livestock and to climatic cycles that influence arroyo formation. Considerable effort has been directed toward the influence of livestock grazing on riparian species abundance and diversity. Less work has concentrated on the...

Petroleum geology and resources of the West Siberian Basin, Russia

USGS Publications Warehouse

Ulmishek, Gregory F.

2003-01-01

The West Siberian basin is the largest petroleum basin in the world covering an area of about 2.2 million km2. The basin occupies a swampy plain between the Ural Mountains and the Yenisey River. On the north, the basin extends offshore into the southern Kara Sea. On the west, north, and east, the basin is surrounded by the Ural, Yenisey Ridge, and Turukhan-Igarka foldbelts that experienced major deformations during the Hercynian tectonic event and the Novaya Zemlya foldbelt that was deformed in early Cimmerian (Triassic) time. On the south, the folded Caledonian structures of the Central Kazakhstan and Altay-Sayan regions dip northward beneath the basin?s sedimentary cover. The basin is a relatively undeformed Mesozoic sag that overlies the Hercynian accreted terrane and the Early Triassic rift system. The basement is composed of foldbelts that were deformed in Late Carboniferous?Permian time during collision of the Siberian and Kazakhstan continents with the Russian craton. The basement also includes several microcontinental blocks with a relatively undeformed Paleozoic sedimentary sequence. The sedimentary succession of the basin is composed of Middle Triassic through Tertiary clastic rocks. The lower part of this succession is present only in the northern part of the basin; southward, progressively younger strata onlap the basement, so that in the southern areas the basement is overlain by Toarcian and younger rocks. The important stage in tectono-stratigraphic development of the basin was formation of a deep-water sea in Volgian?early Berriasian time. The sea covered more than one million km2 in the central basin area. Highly organic-rich siliceous shales of the Bazhenov Formation were deposited during this time in anoxic conditions on the sea bottom. Rocks of this formation have generated more than 80 percent of West Siberian oil reserves and probably a substantial part of its gas reserves. The deep-water basin was filled by prograding clastic clinoforms during Neocomian time. The clastic material was transported by a system of rivers dominantly from the eastern provenance. Sandstones within the Neocomian clinoforms contain the principal oil reservoirs. The thick continental Aptian?Cenomanian Pokur Formation above the Neocomian sequence contains giant gas reserves in the northern part of the basin. Three total petroleum systems are identified in the West Siberian basin. Volumes of discovered hydrocarbons in these systems are 144 billion barrels of oil and more than 1,300 trillion cubic feet of gas. The assessed mean undiscovered resources are 55.2 billion barrels of oil, 642.9 trillion cubic feet of gas, and 20.5 billion barrels of natural gas liquids. The largest known oil reserves are in the Bazhenov-Neocomian total petroleum system that includes Upper Jurassic and younger rocks of the central and southern parts of the basin. Oil reservoirs are mainly in Neocomian and Upper Jurassic clastic strata. Source rocks are organic-rich siliceous shales of the Bazhenov Formation. Most discovered reserves are in structural traps, but stratigraphic traps in the Neocomian clinoform sequence are pro-ductive and are expected to contain much of the undiscovered resources. Two assessment units are identified in this total petroleum system. The first assessment unit includes all conventional reservoirs in the stratigraphic interval from the Upper Jurassic to the Cenomanian. The second unit includes unconventional (or continuous), self-sourced, fractured reservoirs in the Bazhenov Formation. This unit was not assessed quantitatively. The Togur-Tyumen total petroleum system covers the same geographic area as the Bazhenov-Neocomian system, but it includes older, Lower?Middle Jurassic strata and weathered rocks at the top of the pre-Jurassic sequence. A Callovian regional shale seal of the Abalak and lower Vasyugan Formations separates the two systems. The Togur-Tyumen system is oil-prone; gas reserves are insignificant. The principal o

Effects of hydraulic and geologic factors on streamflow of the Yakima River Basin, Washington

USGS Publications Warehouse

Kinnison, Hallard B.; Sceva, Jack E.

1963-01-01

The Yakima River basin, in south-central Washington, is the largest single river system entirely within the confines of the State. Its waters are the most extensively utilized of all the rivers in Washington. The river heads high on the eastern slope of the Cascade Mountains, flows for 180 miles in a generally southeast direction, and discharges into the Columbia River. The western part of the basin is a mountainous area formed by sedimentary, volcanic, and metamorphic rocks, which generally have a low capacity for storing and transmitting water. The eastern part of the basin is. formed by a thick sequence of lava flows that have folded into long ridges and troughs. Downwarped structural basins between many of the ridges are partly filled with younger sedimentary deposits, which at some places are many hundreds of feet thick. The Yakima River flows from structural basin to structural basin through narrow water gaps that have been eroded through the anticlinal ridges. Each basin is also a topographic basin and a ground-water subbasin. A gaging station will measure the total outflow of a drainage area only if it is located at the surface outlet of a ground-water subbasin and then only if the stream basin is nearly coextensive with the ground-water subbasin. Many gaging stations in the Yakima basin are so located. The geology, hydrology, size. and location of 25 ground-water subbasins are described. Since the settlement of the valley began, the development of the land and water resources have caused progressive changes in the natural regimen of the basin's runoff. These changes have resulted from diversion of water from the streams, the application of water on the land for irrigation, the storage and release of flood waters, the pumping of ground water, and other factors Irrigation in the Yakima basin is reported 'to have begun about 1864. In 1955 about 425,000 acres were under irrigation. During the past 60-odd years many gaging stations have been operated at different sites within the basin. Only stations in the upper reaches, such as those below Keechelus, Kachess, or Cle Elum Lakes, give discharge records which are an accurate measure of the natural outflow of the drainage area. Farther down, stream, as the utilization of water becomes more extensive, the records at a gaging station show the discharge passing a particular point, but they do not reflect the natural outflow of the basin. Large canals divert water for use on lands above a station or carry it around a station for irrigation downstream. The deep sedimentary deposits within subbasins and the overlying alluvial gravels permit downvalley movement of large subsurface flows which bypass the gaging stations, except in the near vicinity of the water gaps. At the water gaps ground water rises to the surface, becoming streamflow, and can be accurately measured. The location of gaging stations within each subbasin is important, therefore, in determining whether the flow measured represents the total downvalley outflow or whether it is merely the surface-water component. Surface and subsurface factors that may affect the discharge records at each gaging station in the Yakima River basin include a description of upstream diversions, surface return flows, bypass canals, storage reservoirs, subsurface bypass flows, ground-water withdrawals, and other items. The available data are not sufficiently complete to permit a quantitative determination of the total basin yield at most gaging stations. However, data on the existing bypass channels, such as canals and drainage ditches, and on related subsurface movement of water provide valuable information necessary to proper use and interpretation of the streamflow records.

Long-period effects of the Denali earthquake on water bodies in the Puget Lowland: Observations and modeling

USGS Publications Warehouse

Barberopoulou, A.; Qamar, A.; Pratt, T.L.; Steele, W.P.

2006-01-01

Analysis of strong-motion instrument recordings in Seattle, Washington, resulting from the 2002 Mw 7.9 Denali, Alaska, earthquake reveals that amplification in the 0.2-to 1.0-Hz frequency band is largely governed by the shallow sediments both inside and outside the sedimentary basins beneath the Puget Lowland. Sites above the deep sedimentary strata show additional seismic-wave amplification in the 0.04- to 0.2-Hz frequency range. Surface waves generated by the Mw 7.9 Denali, Alaska, earthquake of 3 November 2002 produced pronounced water waves across Washington state. The largest water waves coincided with the area of largest seismic-wave amplification underlain by the Seattle basin. In the current work, we present reports that show Lakes Union and Washington, both located on the Seattle basin, are susceptible to large water waves generated by large local earthquakes and teleseisms. A simple model of a water body is adopted to explain the generation of waves in water basins. This model provides reasonable estimates for the water-wave amplitudes in swimming pools during the Denali earthquake but appears to underestimate the waves observed in Lake Union.

Evaluating controls on fluvial sand-body clustering in the Ferris Formation (Cretaceous/Paleogene, Wyoming, USA)

NASA Astrophysics Data System (ADS)

Hajek, E. A.; Heller, P.

2009-12-01

A primary goal of sedimentary geologists is to interpret past tectonic, climatic, and eustatic conditions from the stratigraphic record. Stratigraphic changes in alluvial-basin fills are routinely interpreted as the result of past tectonic movements or changes in climate or sea level. Recent physical and numerical models have shown that sedimentary systems can exhibit self-organization on basin-filling time scales, suggesting that structured stratigraphic patterns can form spontaneously rather than as the result of changing boundary conditions. The Ferris Formation (Upper Cretaceous/Paleogene, Hanna Basin, Wyoming) exhibits stratigraphic organization where clusters of closely-spaced channel deposits are separated from other clusters by intervals dominated by overbank material. In order to evaluate the role of basinal controls on deposition and ascertain the potential for self-organization in this ancient deposit, the spatial patterns of key channel properties (including sand-body dimensions, paleoflow depth, maximum clast size, paleocurrent direction, and sediment provenance) are analyzed. Overall the study area lacks strong trends sand-body properties through the stratigraphic succession and in cluster groups. Consequently there is no indication that the stratigraphic pattern observed in the Ferris Formation was driven by systematic changes in climate or tectonics.

Sedimentology of the upper Karoo fluvial strata in the Tuli Basin, South Africa

NASA Astrophysics Data System (ADS)

Bordy, Emese M.; Catuneanu, Octavian

2001-08-01

The sedimentary rocks of the Karoo Supergroup in the Tuli Basin (South Africa) may be grouped in four stratigraphic units: the basal, middle and upper units, and the Clarens Formation. This paper presents the findings of the sedimentological investigation of the fluvial terrigenous clastic and chemical deposits of the upper unit. Evidence provided by primary sedimentary structures, palaeontological record, borehole data, palaeo-flow measurements and stratigraphic relations resulted in the palaeo-environmental reconstruction of the upper unit. The dominant facies assemblages are represented by sandstones and finer-grained sediments, which both can be interbedded with subordinate intraformational coarser facies. The facies assemblages of the upper unit are interpreted as deposits of a low-sinuosity, ephemeral stream system with calcretes and silcretes in the dinosaur-inhabited overbank area. During the deposition of the upper unit, the climate was semi-arid with sparse precipitation resulting in high-magnitude, low-frequency devastating flash floods. The current indicators of the palaeo-drainage system suggest flow direction from northwest to southeast, in a dominantly extensional tectonic setting. Based on sedimentologic and biostratigraphic evidence, the upper unit of the Tuli Basin correlates to the Elliot Formation in the main Karoo Basin to the south.

Lithogeochemical character of the near-surface bedrock in the Connecticut, Housatonic, and Thames River Basins

USGS Publications Warehouse

Robinson, Gilpin R.; Peper, John D.; Steeves, Peter A.; Desimone, Leslie A.

1999-01-01

This data layer shows the generalized lithologic and geochemical (lithogeochemical) character of near-surface bedrock in the Connecticut, Housatonic, and Thames River Basins and several other small basins that drain into Long Island Sound from Connecticut. The area includes most of Connecticut, western Massachusetts, eastern Vermont, western New Hampshire, and small parts of Rhode Island, New York, and Quebec, Canada.Bedrock geologic rock units are classified into 29 lithogeochemical rock units, on the basis of the relative reactivity of their constituent minerals to dissolution and other weathering reactions and the presence of carbonate or sulfide minerals. The 29 lithogeochemical units (28 of which can be found in the study area) can be grouped into 6 major categories: (1) carbonate-rich rocks, (2) carbonate-poor, clastic sedimentary rocks restricted to distinct depositional basins, (3) metamorphosed, clastic sedimentary rocks (primarily noncalcareous), (4) mafic igneous rocks and their metamorphic equivalents, (5) ultramafic rocks, and (6) felsic igneous and plutonic rocks and their metamorphic equivalents. The lithogeochemical rock units also are grouped into nine lithologic and physiographic provinces (lithophysiographic domains), which can be further grouped into three major regions: (1) western highlands and lowlands, (2) central lowlands, and (3) eastern highlands.

Canada Basin revealed

USGS Publications Warehouse

Mosher, David C.; Shimeld, John; Hutchinson, Deborah R.; Chian, D; Lebedeva-Ivanova, Nina; Jackson, Ruth

2012-01-01

More than 15,000 line-km of new regional seismic reflection and refraction data in the western Arctic Ocean provide insights into the tectonic and sedimentologic history of Canada Basin, permitting development of new geologic understanding in one of Earth's last frontiers. These new data support a rotational opening model for southern Canada Basin. There is a central basement ridge possibly representing an extinct spreading center with oceanic crustal velocities and blocky basement morphology characteristic of spreading centre crust surrounding this ridge. Basement elevation is lower in the south, mostly due to sediment loading subsidence. The sedimentary succession is thickest in the southern Beaufort Sea region, reaching more than 15 km, and generally thins to the north and west. In the north, grabens and half-grabens are indicative of extension. Alpha-Mendeleev Ridge is a large igneous province in northern Amerasia Basin, presumably emplaced synchronously with basin formation. It overprints most of northern Canada Basin structure. The seafloor and sedimentary succession of Canada Basin is remarkably flat-lying in its central region, with little bathymetric change over most of its extent. Reflections that correlate over 100s of kms comprise most of the succession and on-lap bathymetric and basement highs. They are interpreted as representing deposits from unconfined turbidity current flows. Sediment distribution patterns reflect changing source directions during the basin’s history. Initially, probably late Cretaceous to Paleocene synrift sediments sourced from the Alaska and Mackenzie-Beaufort margins. This unit shows a progressive series of onlap unconformities with a younging trend towards Alpha and Northwind ridges, likely a response to contemporaneous subsidence. Sediment source direction appeared to shift to the Canadian Arctic Archipelago margin for the Eocene and Oligocene, likely due to uplift of Arctic islands during the Eurekan Orogeny. The final stage of sedimentation appears to be from the Mackenzie-Beaufort region for the Miocene and Pliocene when drainage patterns shifted in the Yukon and Alaska to the Mackenzie valley. Upturned reflections at onlap positions may indicate syn-depositional subsidence. There is little evidence, at least at a regional seismic data scale, of contemporaneous or post-depositional sediment reworking, suggesting little large-scale geostrophic or thermohaline-driven bottom current activity.

Flashy Water and Sediment Delivery to Fluvial Megafan andFan Delta Systems on Opposing Shorelines of an Early Eocene Lake

NASA Astrophysics Data System (ADS)

Jones, E. R.; Plink-Bjorklund, P.

2015-12-01

Flashy delivery of water and sediment had distinct effects on the process of deposition in coeval fluvial megafan and fan delta deposits on opposing shorelines of a paleolake that occupied the Uinta Basin throughout the Eocene. The Tertiary Uinta Basin was an asymmetric continental interior basin with a steep northern margin, adjacent to the block uplift controlling basin subsidence, and a low gradient southern margin. A ~140 km wide fluvial megafan with catchments as far as ~750 km away occupied the southern margin of the lacustrine basin. Within this megafan system, fluvial deposits contain within-channel continental bioturbation and paleosol development on bar accretion surfaces that are evidence of prolonged periods of groundwater flow or channel abandonment. These are punctuated by channel fills exhibiting a suite of both high-deposition rate and upper flow regime sedimentary structures that were deposited by very rapid suspension-fallout during seasonal to episodic river flooding events. A series of small (~8 km wide) and proximally sourced fan deltas fed sediment into the steeper northern margin of the lacustrine basin. 35-50% of the deposits in the delta plain environment of these fan deltas are very sandy debris flows with as low as 5% clay and silt sized material. Detrital zircon geochronology shows that these fan deltas were tapping catchments where mostly unconsolidated Cretaceous sedimentary cover and thick Jurassic eolianites were being eroded. A combination of flashy precipitation, arid climate, catchments mantled by abundant loose sand-sized colluvium, and steep depositional gradients promoted generation of abundant very sandy (5-10% clay and silt sized material) debris flows. In this way, the Wasatch and Green River Formations in the Uinta Basin, Utah, U.S.A. gives us two very different examples of how routing flashy water and sediment delivery (associated with pulses of hyperthermal climate change during the Early Eocene) through different depositional systems produced unique processes of deposition, and also gives us an opportunity to isolate the effects of other variables (e.g. sediment caliber, system gradient, catchment size) that can modulate the flashy precipitation signal in stratigraphy.

Stratigraphy of two conjugate margins (Gulf of Lion and West Sardinia): modeling of vertical movements and sediment budgets

NASA Astrophysics Data System (ADS)

Leroux, Estelle; Gorini, Christian; Aslanian, Daniel; Rabineau, Marina; Blanpied, Christian; Rubino, Jean-Loup; Robin, Cécile; Granjeon, Didier; Taillepierre, Rachel

2016-04-01

The post-rift (~20-0 Ma) vertical movements of the Provence Basin (West Mediterranean) are quantified on its both conjugate (the Gulf of Lion and the West Sardinia) margins. This work is based on the stratigraphic study of sedimentary markers using a large 3D grid of seismic data, correlations with existing drillings and refraction data. The post-rift subsidence is measured by the direct use of sedimentary geometries analysed in 3D [Gorini et al., 2015; Rabineau et al., 2014] and validated by numerical stratigraphic modelling. Three domains were found: on the platform (1) and slope (2), the subsidence takes the form of a seaward tilting with different amplitudes, whereas the deep basin (3) subsides purely vertically [Leroux et al., 2015a]. These domains correspond to the deeper crustal domains respectively highlighted by wide angle seismic data. The continental crust (1) and the thinned continental crust (2) are tilted, whereas the intermediate crust, identified as lower continental exhumed crust [Moulin et al., 2015, Afhilado et al., 2015] (3) sagged. The post-break-up subsidence re-uses the initial hinge lines of the rifting phase. This striking correlation between surface geologic processes and deep earth dynamic processes emphasizes that the sedimentary record and sedimentary markers is a window into deep geodynamic processes and dynamic topography. Pliocene-Pleistocene seismic markers enabled high resolution quantification of sediment budgets over the past 6 Myr [Leroux et al., in press]. Sediment budget history is here completed on the Miocene interval. Thus, the controlling factors (climate, tectonics and eustasy) are discussed. Afilhado, A., Moulin, M., Aslanian, D., Schnürle, P., Klingelhoefer, F., Nouzé, H., Rabineau, M., Leroux, E. & Beslier, M.-O. (2015). Deep crustal structure across a young 1 passive margin from wide-angle and reflection seismic data (The SARDINIA Experiment) - II. Sardinia's margin. Bull. Soc. géol. France, 186, ILP Spec. issue, 4-5, 331-351. Gorini, C., Montadert, L., Rabineau, M., (2015) New imaging of the salinity crisis: Dual Messinian lowstand megasequences recorded in the deep basin of both the eastern and western Mediterranean, Marine and Petroleum Geology (2015), doi: 10.1016/j.marpetgeo.2015.01.009. Leroux, E., Aslanian, D., Rabineau, M., Moulin, M., Granjeon, D., Gorini C. & Droz, L. (2015a). Sedimentary markers in the Provençal basin (Western Mediterranean): a window into deep geodynamic processes. Terra Nova, 27(2), 122-129. Leroux, E., Rabineau, M., Aslanian, D., Gorini, C., Molliex, S., Bache, F., Robin, C., Droz, L., Moulin, M., Poort, J., Rubino, J.-L. & Suc, J.P. (2016, in press). High resolution evolution of terrigenous sediment yields in the Provence Basin during the last 6 Ma: relation with climate and tectonic. Basin Research, xx, xx-xx (ID: 4759575-1545130). Moulin, M., Klingelhoefer, F., Afiladho, A., Aslanian, D., Schnürle, P., Nouze, H., Beslier, M.-O. & Feld, A. (2015). Deep crustal structure across an young passive margin from wide-angle and reflection seismic data (The SARDINIA Experiment) - I. Gulf of Lion's margin, Bull. Soc. géol. France., 186, ILP Spec. issue, 4-5,309-330. Rabineau, M., Leroux, E., Aslanian, D., Bache, F., Gorini, C., Moulin, M., Molliex, S., Droz, L., Reis, T. D., Rubino, J.-L., Guillocheau, F. & Olivet, J.-L. (2014). Quantifying subsidence and isostatic readjustment using sedimentary markers (example in the Gulf of Lion). Earth and Planetary Science Letters, 388, 1-14.

From crustal thinning to mantle exhumation: what the Pyrenean breccia formations tell us.

NASA Astrophysics Data System (ADS)

Clerc, C.; Chauvet, A.; Lagabrielle, Y.; Reynaud, J.-Y.; Boulvais, P.; Bousquet, R.; Lahfid, A.; Vauchez, A.; Mahé, S.

2012-04-01

Several formations with various breccia types occur in Mesozoic basins disseminated along the North Pyrenean fault, on the northern flank of the French Pyrenees. Due to their location along the Iberia-Europa plate boundary, the North Pyrenean breccia formations represent complex archives documenting the tectonic and sedimentary evolution of the Pyrenean realm during the Aptian-Albian period. In particular, the North Pyrenean breccia formations have recorded the main stages of crustal thinning, continental break-up and mantle exhumation, which occurred along the North Pyrenean Zone (NPZ). We will review the main sedimentary, structural, metamorphic and geochemical characters of these breccias, based on new field investigations conducted in both the Western and Eastern Pyrenées (Agly, Aulus, Moncaup-St Béas and Urdach localities). Based on our new founding, we re-intrepret the significance of the breccia formations in the light of the most recent models developed for the pre-orogenic evolution of the Pyrenees. In several places and mostly close to the contact between Paleozoic basement and Mesozoic cover, we systematically recognized the following three types of breccias: i) Semi-ductile syn-metamorphic breccias resulting from the boudinage of silicic or dolomitic beddings in ductily deformed marbles. ii) Cataclastic breccias disturbing the neighbouring host rocks and displaying a relatively monogenetic character. These tectonic breccias result from the disruption of the Mesozoic metamorphic platform under cooling conditions. They are dominated by cataclastic levels mainly located in the Triassic and Liassic weaker levels, iii) Polymictic sedimentary breccias, which composition is dominated by clasts of Mesozoic metasediments. Locally, close to subcontinental mantle bodies, the sedimentary breccias include numerous clasts of ultramafic and/or crustal basement rocks. Such breccias are the witness of the disruption of the sedimentary cover of the North Pyrenean Zone massifs followed by clastic sedimentation in a context of hyper-extended crust and mantle exhumation. Improving the knowledge of the formation of the different types of breccia exposed all along the Northern Pyrenees brings important hints to decipher the tectonic history responsible for the formation of the metamorphic basins and the exhumation (and reworking) of deep crustal and mantle rocks in the NPZ.

Basin analysis of tertiary strata in the Pattani Basin, Gulf of Thailand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chonchawalit, A.; Bustin, R.M.

The stratigraphic and structural evolution of the Pattani basin, the most prolific petroleum basin in Thailand, reflects the extensional tectonics of continental southeast Asia. East-west extension, a product of the northward collision of India with Eurasia since the early Tertiary resulted in the formation of a series of north-south-trending sedimentary basins including the Pattani basin. Subsidence and thermal histories of the basin can generally be accounted for by nonuniform lithospheric stretching. The validity of nonuniform lithospheric stretching as a mechanic for the formation of the Pattani basin is confirmed by a reasonably good agreement between modeled and observed vitrinite reflectancemore » at various depths and locations. The amount of stretching and surface heat flow generally increases from the basin margin to the basin center. Crustal stretching factor ([beta]) ranges from 1.3 at the basin margin to 2.8 in the center. Subcrustal stretching factor ([sigma]) ranges from 1.3 at the margin to more than 3.0 in the center. The stretching of the lithosphere may have extended basement rocks as much as 45 to 90 km and may have caused the upwelling of asthenosphere, resulting in high heat flow. The sedimentary succession in the Pattani basin is divisible into synrift and postrift sequences. The synrift sequences comprise (1) late Eocene ( ) to early Oligocene alluvial fan, braided river, and flood-plain deposits; (2) late Oligocene to early Miocene floodplain and channel deposits; and (3) an early Miocene regressive package of marine to nonmarine sediments. Deposition of synrift sequences corresponded to rifting and extension, which included episodic block faulting and rapid subsidence. Postrift succession comprises (1) an early to middle Miocene regressive package of shallow marine to nonmarine sediments, (2) a late early Miocene transgressive package; and (3) a late Miocene to Pleistocene transgression succession.« less

Climate and Tectonics Need Not Apply: Transient Erosion Driven by Drainage Integration, Aravaipa Creek, AZ

NASA Astrophysics Data System (ADS)

Jungers, M.; Heimsath, A. M.

2013-12-01

Periods of transient erosion during landscape evolution are most commonly attributed to fluvial systems' responses to changes in tectonic or climatic forcing. Dramatic changes in base level and sudden increases in drainage area associated with drainage reorganization can, however, drive punctuated events of incision and erosion equal in magnitude to those driven by tectonics or climate. In southeastern Arizona's Basin and Range, a mature portion of the North American physiographic province, the modern Gila River system integrates a network of previously internally drained structural basins. One basin in particular, Aravaipa Creek, is the most recent to join the broader Gila River fluvial network. Following drainage integration, Aravaipa Creek rapidly incised to equilibrate with its new, much lower, base level. In doing so, it carved Aravaipa Canyon, excavated a large volume of sedimentary basin fill, and captured drainage area from the still internally drained Sulphur Springs basin. Importantly, this dramatic episode of transient incision and erosion was the result of drainage integration alone. We hypothesize that the adjustment time for Aravaipa Creek was shorter than the timescale of any climate forcing, and regional extensional tectonics were quiescent at the time of integration. We can, therefore, explicitly quantify the magnitude of transient incision and erosion driven by drainage reorganization. We use remnants of the paleo-basin surface and modern landscape elevations to reconstruct the pre-drainage integration topography of Aravaipa Creek basin. Doing so enables us to quantify the magnitude of incision driven by drainage reorganization as well as the volume of material eroded from the basin subsequent to integration. Key control points for our landscape reconstruction are: (1) the inferred elevation of the spillover point between Aravaipa Creek and the San Pedro River; (2) Quaternary pediment-capping gravels above Aravaipa Canyon (3) perched remnants of late stage sedimentary basin fill that preserve the slope of the pre-incision piedmonts of the Galiuro Mountains and Santa Teresa Mountains; and (4) the paleo-drainage divide between Aravaipa Creek and Sulphur Springs Valley, approximately 6 km northwest of the modern divide. The pre-incision basin surface sloped from the Sulphur Springs divide (1370 m) to its intersection with the point of integration (1100 m) between Aravaipa Creek and the San Pedro River, 50 km to the northwest. Maximum incision of 450 m occurred in the vicinity of Aravaipa Canyon, and more than 50 cubic kilometers of material have been eroded from Aravaipa Creek basin. Finally, cosmogenic nuclide burial dates for latest stage sedimentary basin fill enable us to constrain the timing of drainage integration and place first-order constraints on paleo-erosion rates.

Evolution of tholeiitic diabase sheet systems in the eastern United States: examples from the Culpeper Basin, Virginia-Maryland, and the Gettysburg Basin, Pennsylvania

USGS Publications Warehouse

Woodruff, L.G.; Froelich, A.J.; Belkin, H.E.; Gottfried, D.

1995-01-01

High-TiO2, quartz-normative (HTQ) tholeiite sheets of Early Jurassic age have intruded mainly Late Triassic sedimentary rocks in several early Mesozoic basins in the eastern US. Field observations, petrographic study, geochemical analyses and stable isotope data from three HTQ sheet systems were used to develop a general model of magmatic differentiation and magmatic-hydrothermal interaction for HTQ sheets. The three sheet systems have remarkably similar major-oxide and trace-element compositions. Cumulus and evolved diabase in comagmatic sheets separated by tens of kilometers are related by igneous differentiation. Differentiated diabase in all three sheets have petrographic and geochemical signatures and fluid inclusions indicating hydrothermal alteration beginning near magmatic temperatures and continuing to relatively low temperatures. Sulfur and oxygen isotope data are consistent with a magmatic origin for the hydrothermal fluid. -from Authors

Simulation of groundwater storage changes in the eastern Pasco Basin, Washington

USGS Publications Warehouse

Heywood, Charles E.; Kahle, Sue C.; Olsen, Theresa D.; Patterson, James D.; Burns, Erick

2016-03-29

The Miocene Columbia River Basalt Group and younger sedimentary deposits of lacustrine, fluvial, eolian, and cataclysmic-flood origins compose the aquifer system of the Pasco Basin in eastern Washington. Irrigation return flow and canal leakage from the Columbia Basin Project have caused groundwater levels to rise substantially in some areas, contributing to landslides along the Columbia River. Water resource managers are considering extraction of additional stored groundwater to supply increasing demand and possibly mitigate problems caused by the increased water levels. To help address these concerns, the transient groundwater model of the Pasco Basin documented in this report was developed to quantify the changes in groundwater flow and storage. The MODFLOW model uses a 1-kilometer finite-difference grid and is constrained by logs and water levels from 846 wells in the study area. Eight model layers represent five sedimentary hydrogeologic units and underlying basalt formations. Head‑dependent flux boundaries represent the Columbia and Snake Rivers to the west and south, respectively, underflow to and (or) from adjacent areas to the northeast, and discharge to agricultural drains, springs, and groundwater withdrawal wells. Specified flux boundaries represent recharge from infiltrated precipitation and anthropogenic sources, including irrigation return flow and leakage from water-distribution canals. The model was calibrated with the parameter‑estimation code PEST++ to groundwater levels measured from 1907 through 2013 and measured discharge to springs and estimated discharge to agricultural drains. Increased recharge since pre-development resulted in a 6.8 million acre-feet increase in storage in the 508-14 administrative area of the Pasco Basin. Four groundwater-management scenarios simulate the 7-year drawdown resulting from withdrawals in different locations. Withdrawals of 2 million gallons per day (Mgal/d) from a hypothetical well field in the upper Ringold Formation along the Columbia River could generate 30–70 feet of drawdown, which may reduce landslide susceptibility along the White Bluffs. Drawdowns resulting from a 1 Mgal/d withdrawal from wells screened in either Pasco gravels, upper Ringold Formation, or both Ringold Formation and underlying basalt are simulated in the other three scenarios, and differ because of the contrasting hydraulic conductivities within the screened intervals.

The beginning of the Buntsandstein cycle (Early-Middle Triassic) in the Catalan Ranges, NE Spain: Sedimentary and palaeogeographic implications

NASA Astrophysics Data System (ADS)

Galán-Abellán, Belén; López-Gómez, José; Barrenechea, José F.; Marzo, Mariano; De la Horra, Raúl; Arche, Alfredo

2013-10-01

The Early-Middle Triassic siliciclastic deposits of the Catalan Ranges, NE Spain, are dominated by aeolian sediments indicating a predominance of arid climate during this time span, in sharp contrast with the coeval fluvial sediments found in the Castilian Branch of the Iberian Ranges, 300 km to the SW. The NE-SW-oriented Catalan Basin evolved during the Middle-Late Permian as the result of widespread extension in the Iberian plate. This rift basin was bounded by the Pyrenees, Ebro and Montalbán-Oropesa highs. The Permian-Early Triassic-age sediments of the Catalan Basin were deposited in three isolated subbasins (Montseny, Garraf, Prades), separated by intrabasinal highs, but linked by transversal NW-SE oriented faults. The three subbasins show evidence of diachronic evolution with different subsidence rates and differences in their sedimentary records. The Buntsandstein sedimentary cycle started in the late Early Triassic (Smithian-Spathian) in the central and southern domains (Garraf and Prades), with conglomerates of alluvial fan origin followed by fluvial and aeolian sandstones. Source area of the fluvial sediments was nearby Paleozoic highs to the north and west, in contrast with the far-away source areas of the fluvial sediments in the Iberian Ranges, to the SW. These fluvial systems were interacting with migrating aeolian dune fields located towards the S, which developed in the shadow areas behind the barriers formed by the Paleozoic highs. These highs were separating the subbasins under arid and semi-arid climate conditions. The dominating winds came from the east where the westernmost coast of the Tethys Sea was located, and periods of water run-off and fields of aeolian dunes development alternated. Some of the fluvial systems were probably evaporating as they were mixed into the interdune areas, never reaching the sea. From the end of the Smithian to the Spathian, the Catalan Basin and neighbour peri-Tethys basins of the present-day southern France, Sardinia and Minorca islands constituted a geographical arch where arid and semi-arid conditions represented an extension of the prevailed arid and hyper-arid conditions in surrounding areas of the Variscan Belt. Harsh climatic conditions in this area prevented the life recovery in the aftermath of the Permian-Triassic extinction event until the early Anisian, when more humid climate allowed for the colonisation of the area by plants, amphibians and reptiles. The boundary between desert areas and semi-arid and/or seasonal climate domains during the Smithian-Spathian in SW Europe can be precisely established in NE Iberia, between the Catalan-Ebro region and the Castilian Branch of the Iberian Ranges, to the SW.

Sedimentary processes and depositional environments of the Horn River Shale in British Columbia, Canada

NASA Astrophysics Data System (ADS)

Yoon, Seok-Hoon; Koh, Chang-Seong; Joe, Young-Jin; Woo, Ju-Hwan; Lee, Hyun-Suk

2017-04-01

The Horn River Basin in the northeastern British Columbia, Canada, is one of the largest unconventional gas accumulations in North America. It consists mainly of Devonian shales (Horn River Formation) and is stratigraphically divided into three members, the Muskwa, Otterpark and Evie in descending order. This study focuses on sedimentary processes and depositional environments of the Horn River shale based on sedimentary facies analysis aided by well-log mineralogy (ECS) and total organic carbon (TOC) data. The shale formation consists dominantly of siliceous minerals (quartz, feldspar and mica) and subordinate clay mineral and carbonate materials, and TOC ranging from 1.0 to 7.6%. Based on sedimentary structures and micro texture, three sedimentary facies were classified: homogeneous mudstone (HM), indistinctly laminated mudstone (ILM), and planar laminated mudstone (PLM). Integrated interpretation of the sedimentary facies, lithology and TOC suggests that depositional environment of the Horn River shale was an anoxic quiescent basin plain and base-of-slope off carbonate platform or reef. In this deeper marine setting, organic-rich facies HM and ILM, dominant in the Muskwa (the upper part of the Horn River Formation) and Evie (the lower part of the Horn River Formation) members, may have been emplaced by pelagic to hemipelagic sedimentation on the anoxic sea floor with infrequent effects of low-density gravity flows (turbidity currents or nepheloid flows). In the other hand, facies PLM typifying the Otterpark Member (the middle part of the Horn River Formation) suggests more frequent inflow of bottom-hugging turbidity currents punctuating the hemipelagic settling of the background sedimentation process. The stratigraphic change of sedimentary facies and TOC content in the Horn River Formation is most appropriately interpreted to have been caused by the relative sea-level change, that is, lower TOC and frequent signal of turbidity current during the sea-level lowstand and vice versa. Therefore, the Horn River Formation represents an earlier upward shallowing environmental change from a deep basin (Evie) to shallower marginal slope (middle Otterpark), then turning back to the deeper marine environment (Muskwa) in association with overall regression-lowstand-transgression of the sea level. (This study is supported by "Research on Exploration Technologies and an Onsite Verification to Enhance the Fracturing Efficiency of a Shale Gas Formation" of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea.)

Using apatite fission track thermochronology to document the deformation sequence in an exhumed foreland basin: an example from the southern Pyrenees.

NASA Astrophysics Data System (ADS)

Meresse, F.; Labaume, P.; Jolivet, M.; Teixell, A.

2009-04-01

Université Montpellier 2, INSU-CNRS, Laboratoire Géosciences Montpellier, cc060, 34095 Montpellier Cedex 5, France florian.meresse@gm.univ-montp2.fr The study of foreland basins provides important constraints on the evolution of orogenic wedges. In particular, the study of tectonics-sedimentation relationships is essential to date the tectonic activity. However, processes linked to wedge growth are not always completely recorded by the tecto-sedimentary markers, and thermochronological study of the basin-fill can provide further insights. In this work, we have combined apatite fission track analysis (apatite FTA) with structural analysis to precise the timing of the deformation sequence and to characterise the coupling between thrust activity, burial and denudation in the south-Pyrenean foreland basin, a proximal foredeep of the Pyrenees that has been incorporated in the Pyrenean thrust wedge. We have focused the study on a NNE-SSW cross-section of the south-vergent thrust system from the southern flank of the Axial Zone to the South-Pyrenean Frontal Thrust (SPFT), in the west-central part of the belt. This section provides a complete transverse of the South-Pyrenean Zone, here corresponding to the Ainsa and Jaca basins. Apatite FTA provides important new constraints on the south-Pyrenean foreland basin evolution: (i) Data show the southward decrease of the fission track reset level, from a total reset (indicating heating at Tmax>110°C) in the Paleozoic of the Axial Zone, to a partial reset (110°C>Tmax>60°C) in the lower-middle Eocene Hecho Group turbidites in the northern part of the Jaca basin, and to the absence of reset (Tmax<60°C) in the middle Eocene-Oligocene continental sediments of the southern part of the Jaca basin. This indicates a decreasing amount of denudation going southwards, from more than 4.5 km in the north to less than 2.5 km in the south if we assume an average geothermal gradient around 25°/km. The structural setting of the Jaca basin attests that the burial of sediments was mainly due to sedimentary accumulation. (ii) Results in the Hecho Group turbidites bring evidence of exhumation around 18 Ma on the Oturia thrust in the middle of the Jaca basin, an age that is younger than the Middle Eocene to Aquitanian deformation registered by tecto-sedimentary relationships in the southernmost part of the basin (Guarga syncline and SPFT). These tectonic movements may be related to the exhumation, at the same time, of the southern flank of the Axial Zone by out-of-sequence thrusting on the Bielsa basement thrust (Jolivet et al., 2007*). Therefore, low-temperature thermochronology reveals an out-of-sequence episode of deformation in the interior of the south-Pyrenean thrust wedge that had remained unknown due to the lack of related sedimentary record. This late tectonic activity is younger than the generally admitted Aquitanian age for the end of the Pyrenean compression, and would be linked to an ultimate internal thickening stage in the orogenic wedge (Meresse et al., this volume). (*Tectonics, 2007, vol. 26, doi: 10.1029/2006TC002080)

Tertiary stratigraphy and basin evolution, southern Sabah (Malaysian Borneo)

NASA Astrophysics Data System (ADS)

Balaguru, Allagu; Nichols, Gary

2004-08-01

New mapping and dating of strata in the southern part of the Central Sabah Basin in northern Borneo has made it possible to revise the lithostratigraphy and chronostratigraphy of the area. The recognition in the field of an Early Miocene regional unconformity, which may be equivalent to the Deep Regional Unconformity recognised offshore, has allowed the development of a stratigraphic framework of groups and formations, which correspond to stages in the sedimentary basin development of the area. Below the Early Miocene unconformity lies ophiolitic basement, which is overlain by an accretionary complex of Eocene age and a late Paleogene deep water succession which formed in a fore-arc basin. The late Paleogene deposits underwent syn-depositional deformation, including the development of extensive melanges, all of which can be demonstrated to lie below the unconformity in this area. Some localised limestone deposition occurred during a period of uplift and erosion in the Early Miocene, following which there was an influx of clastic sediments deposited in delta and pro-deltaic environments in the Middle Miocene. These deltaic to shallow marine deposits are now recognised as forming two coarsening-upward successions, mapped as the Tanjong and Kapilit Formations. The total thickness of these two formations in the Central Sabah Basin amounts to 6000 m, only half of the previous estimates, although the total stratigraphic thickness of Cenozoic clastic strata in Sabah may be more than 20,000 m.

Influence of deep sedimentary basins, crustal thining, attenuation, and topography on regional phases: selected examples from theEastern Mediteranean and the Caspian Sea Regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldstein, P.; Schultz, C.; Larsen, S.

1997-07-15

Monitoring of a CTBT will require transportable seismic identification techniques, especially in regions where there is limited data. Unfortunately, most existing techniques are empirical and can not be used reliably in new regions. Our goal is to help develop transportable regional identification techniques by improving our ability to predict the behavior of regional phases and discriminants in diverse geologic regions and in regions with little or no data. Our approach is to use numerical modeling to understand the physical basis for regional wave propagation phenomena and to use this understanding to help explain observed behavior of regional phases and discriminants.more » In this paper, we focus on results from simulations of data in selected regions and investigate the sensitivity of these regional simulations to various features of the crustal structure. Our initial models use teleseismically estimated source locations, mechanisms, and durations and seismological structures that have been determined by others. We model the Mb 5.9, October 1992, Cairo Egypt earthquake at a station at Ankara Turkey (ANTO) using a two-dimensional crustal model consisting of a water layer over a deep sedimentary basin with a thinning crust beneath the basin. Despite the complex tectonics of the Eastern Mediterranean region, we find surprisingly good agreement between the observed data and synthetics based on this relatively smooth two-dimensional model.« less

Seismic Characterization of the Jakarta Basin

NASA Astrophysics Data System (ADS)

Cipta, A.; Saygin, E.; Cummins, P. R.; Masturyono, M.; Rudyanto, A.; Irsyam, M.

2015-12-01

Jakarta, Indonesia, is home to more than 10 million people. Many of these people live in seismically non-resilient structures in an area that historical records suggest is prone to earthquake shaking. The city lies in a sedimentary basin composed of Quaternary alluvium that experiences rapid subsidence (26 cm/year) due to groundwater extraction. Forecasts of how much subsidence may occur in the future are dependent on the thickness of the basin. However, basin geometry and sediment thickness are poorly known. In term of seismic hazard, thick loose sediment can lead to high amplification of seismic waves, of the kind that led to widespread damage in Mexico city during the Michoacan Earthquake of 1985. In order to characterize basin structure, a temporary seismograph deployment was undertaken in Jakarta in Oct 2013- Jan 2014. A total of 96 seismic instrument were deployed throughout Jakarta were deployed throughout Jakarta at 3-5 km spacing. Ambient noise tomography was applied to obtain models of the subsurface velocity structure. Important key, low velocity anomalies at short period (<8s) correspond to the main sedimentary sub-basins thought to be present based on geological interpretations of shallow stratigraphy in the Jakarta Basin. The result shows that at a depth of 300 m, shear-wave velocity in the northern part (600 m/s) of the basin is lower than that in the southern part. The most prominent low velocity structure appears in the northwest of the basin, down to a depth of 800 m, with velocity as low as 1200 m/s. This very low velocity indicates the thickness of sediment and the variability of basin geometry. Waveform computation using SPECFEM2D shows that amplification due to basin geometry occurs at the basin edge and the thick sediment leads to amplification at the basin center. Computation also shows the longer shaking duration occurrs at the basin edge and center of the basin. The nest step will be validating the basin model using earthquake events recorded by the Jakarta array. The Bohol 2013 earthquake is one good candidate event for model validation. This will require using a source model for the Bohol earthquake and a plane wave input to SPECFEM3D.

Sedimentary and pore water geochemistry linked to deglaciation and postglacial development of Lake Vättern, Sweden

NASA Astrophysics Data System (ADS)

Swärd, Henrik; O´Regan, Matt; Kylander, Malin; Greenwood, Sarah; Mörth, Magnus; Jakobsson, Martin

2017-04-01

Lake Vättern, in south central Sweden, underwent profound environmental changes during the Late Weichselian deglaciation of Fennoscandia. It evolved from (i) a sub/proglacial lake situated at the westernmost rim of the Baltic Ice Lake (BIL) into (ii) a brackish to marine phase where the Vättern basin was a part of the Yoldia Sea connecting the North and Baltic Seas, and finally to (iii) a freshwater basin as isostatic rebound following deglaciation led to its isolation. The sedimentary and pore water geochemical signatures associated with these dramatic environmental changes were investigated in a 74 m composite sediment core from southern Lake Vättern. This was accomplished using high-resolution X-ray fluorescence measurements of elemental data along with discrete measurements of total organic carbon (TOC), δ13C, mineralogical composition (XRD) and pore water chemistry. Proglacial sediments in Lake Vättern are devoid of organic matter, and show cyclic trends in elemental data, grain size and mineralogy. These are interpreted as varved sediments whose thickness decreases upcore from decimeters to millimeters. The coarse grained varves are enriched in Ca, Si, Zr and Sr and contain calcite while the fine grained varves are enriched in K, Rb, Ti and Fe and lack calcite. Overall, the presence of calcite is limited to the proglacial sediments and reflected in the elemental data by an abrupt decrease of Ca at the (i)/(ii) transition. This suggests a glacial/glaciofluvial origin for the calcite, likely eroded from local limestones that borders the lake basin in the northeast. The saline incursion at the beginning of phase (ii) is evident in pore water chemistry by a significant increase of the major sea water species (Cl, Na, Mg, K and Ca) but is not clearly seen in the sedimentary geochemistry. Increased biological production in and around the lake during stage (iii) is strongly reflected in sedimentary geochemistry showing decreasing detrital inputs, increasing TOC and δ13C signals and a mineralogical composition that resembles the fine grained varves of the proglacial sediments, but with a more intense quartz signal. Furthermore, pore water profiles show substantial increase in the concentration of redox sensitive species (Fe, Mn and P) indicating anoxic biodegradation in the sediments.

Clastic rocks associated with the Midcontinent rift system in Iowa

USGS Publications Warehouse

Anderson, Raymond R.; McKay, Robert M.

1997-01-01

The Middle Proterozoic Midcontinent Rift System (MRS) of North America is a failed rift that formed in response to region-wide stresses about 1,100 Ma. In Iowa, the MRS is buried beneath 2,200?3,500 ft of Paleozoic and Mesozoic sedimentary rocks and Quaternary glaciogenic deposits. An extremely large volume of sediments was deposited within basins associated with the rift at several stages during its development. Although the uplift of a rift-axial horst resulted in the erosional removal of most of these clastic rocks from the central region of the MRS in Iowa, thick sequences are preserved in a series of horst-bounding basins. Recent studies incorporating petrographic analysis, geophysical modeling, and other analytical procedures have led to the establishment of a preliminary stratigraphy for these clastic rocks and interpretations of basin geometries. This information has allowed the refinement of existing theories and history of MRS formation in Iowa. Additionally, drill samples previously interpreted as indicating the existence of early Paleozoic basins overlying the Proterozoic MRS basins were re-examined. Samples previously interpreted as deep-lying Paleozoic rocks are now known to have caved from upper levels of the drillhole and were out of stratigraphic position. No deep Paleozoic basins exist in this area. These investigations led to the development of petrographic parameters useful in differentiating the Proterozoic MRS Red clastics from Paleozoic clastic rocks having similar lithologies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nyagah, K.; Cloeter, J.J.; Maende, A.

The Lamu basin occupies the coastal onshore and offshore areas of south-east Kenya. This fault bounded basin formed as a result of the Paleozoic-early Mesozoic phase of rifting that developed at the onset of Gondwana dismemberment. The resultant graben was filled by Karroo (Permian-Early Jurassic) continental siliciclastic sediments. Carbonate deposits associated with the Tethyan sea invasion, dominate the Middle to Late Jurassic basin fill. Cessation of the relative motion between Madagascar and Africa in the Early Cretaceous, heralded passive margin development and deltaic sediment progradation until the Paleogene. Shallow seas transgressed the basin in the Miocene when another carbonate regimemore » prevailed. The basin depositional history is characterized by pulses of transgressive and regressive cycles, bounded by tectonically enhanced unconformities dividing the total sedimentary succession into discrete megasequences. Source rock strata occur within Megasequence III (Paleogene) depositional cycle and were lowered into the oil window in Miocene time, when the coastal parts of the basin experienced the greatest amount of subsidence. The tectono-eustatic pulses of the Tertiary brought about source and reservoir strata into a spatial relationship in which hydrocarbons could be entrapped. A basement high on the continental shelf has potential for Karroo sandstone and Jurassic limestone reservoirs. Halokinesis of Middle Jurassic salt in Miocene time provides additional prospects in the offshore area. Paleogene deltaic sands occur in rotated listric fault blacks. A Miocene reef Play coincides with an Eocene source rock kitchen.« less

Lower permian reef-bank bodies’ characterization in the pre-caspian basin

NASA Astrophysics Data System (ADS)

Wang, Zhen; Wang, Yankun; Yin, Jiquan; Luo, Man; Liang, Shuang

2018-02-01

Reef-bank reservoir is one of the targets for exploration of marine carbonate rocks in the Pre-Caspian Basin. Within this basin, the reef-bank bodies were primarily developed in the subsalt Devonian-Lower Permian formations, and are dominated by carbonate platform interior and margin reef-banks. The Lower Permian reef-bank present in the eastern part of the basin is considered prospective. This article provides a sequence and sedimentary facies study utilizing drilling and other data, as well as an analysis and identification of the Lower Permian reef-bank features along the eastern margin of the Pre-Caspian Basin using sub-volume coherence and seismic inversion techniques. The results indicate that the sub-volume coherence technique gives a better reflection of lateral distribution of reefs, and the seismic inversion impedance enables the identification of reef bodies’ development phases in the vertical direction, since AI (impedance) is petrophysically considered a tool for distinguishing the reef limestone and the clastic rocks within the formation (limestone exhibits a relatively high impedance than clastic rock). With this method, the existence of multiple phases of the Lower Permian reef-bank bodies along the eastern margin of the Pre-Caspian Basin has been confirmed. These reef-bank bodies are considered good subsalt exploration targets due to their lateral connectivity from south to north, large distribution range and large scale.

Geologic map and database of the Roseburg 30' x 60' quadrangle, Douglas and Coos counties, Oregon

USGS Publications Warehouse

Wells, Ray E.; Jayko, A.S.; Niem, A.R.; Black, G.; Wiley, T.; Baldwin, E.; Molenaar, K.M.; Wheeler, K.L.; DuRoss, C.B.; Givler, R.W.

2001-01-01

The Roseburg 30' x 60' Quadrangle covers the southeastern margin of the Oregon Coast Range and its tectonic boundary with Mesozoic terranes of the Klamath Mountains (see figures 1 and 2 in pamphlet, also shown on map sheet). The geologic framework of the Roseburg area was established by the pioneering work of Diller (1898), Wells and Peck, (1961) and Ewart Baldwin (1974) and his students (see figure 3 in pamphlet, also shown on map sheet). Baldwin and his students focussed on the history of the Eocene Tyee basin, where the sediments lap across the tectonic boundary with the Mesozoic terranes and record the accretion of the Coast Range basement to the continent. Others have examined the sedimentary fill of the Tyee basin in detail, recognizing the deep marine turbidite facies of the Tyee Formation (Snavely and others, 1964) and proposing several models for the Eocene evolution of the forearc basin (Heller and Ryberg, 1983; Chan and Dott, 1983; Heller and Dickinson, 1985; Molenaar, 1985; see Ryu and others, 1992 for a comprehensive summary). Along the eastern margin of the quadrangle, both the Tyee basin and the Klamath terranes are overlain by Eocene volcanic rocks of the Western Cascade arc (Walker and MacLeod, 1991). The thick Eocene sedimentary sequence of the Tyee basin has significant oil and gas potential (Armentrout and Suek, 1985; Gautier and others, 1993; Ryu and others, 1996). Although 13 deep test wells have been drilled in the Roseburg quadrangle (see figure 2 and table 1 in pamphlet, also shown on map sheet), exploration to date has been hampered by an incomplete understanding of the basin�s tectonic setting and evolution. In response, the Oregon Department of Geology and Mineral Industries (DOGAMI) initiated a five year assessment of the oil and gas potential of the Tyee basin. This map is a product of a cooperative effort by the U. S. Geological Survey, Oregon State University, and DOGAMI to systematically map the sedimentary facies and structure of the Tyee basin. New geologic mapping of twenty-eight 7.5' quadrangles is summarized on the map (see figure 3, also shown on map sheet), and the digital database contains geologic information suitable for both 1:100K and 1:24K scale analysis. DOGAMI has published a compilation and synthesis of previous mapping (Niem and Niem, 1990), a basin-wide sequence stratigraphic model and correlations (Ryu and others, 1992), and a report on the oil and gas potential (Ryu and others, 1996). Readers interested in the oil and gas potential of the Roseburg quadrangle should use the map in combination with Ryu and others (1996) to address specific stratigraphic units and structural plays. Stratigraphic terminology for the Tyee basin adopts the type sections, formation names, and framework of Ryu and others (1992, 1996), which were developed concurrently with the mapping and are recognized throughout the basin. For detailed discussion of nomenclature, type sections, lithology, thickness and distribution, age, contact relationships, and depositional environment of stratigraphic units, the reader is referred to Ryu and others (1992). In this report we focus on the spatial, temporal, and structural relationships between units revealed by geologic mapping. Map unit ages (see figure 4 in pamphlet, also shown on map sheeet) are adjusted slightly from Ryu and others (1992, 1996) to fit new coccolith age determinations (D. Bukry, cited in pamphlet), paleomagnetic polarity data (Simpson, 1977 and new data cited in pamphlet), and the time scale of Berggren and others (1995).

Duvernay shale lithofacies distribution analysis in the West Canadian Sedimentary Basin

NASA Astrophysics Data System (ADS)

Zhu, Houqin; Kong, Xiangwen; Long, Huashan; Huai, Yinchao

2018-02-01

In the West Canadian Sedimentary Basin (WCSB), Duvernay shale is considered to contribute most of the Canadian shale gas reserve and production. According to global shale gas exploration and development practice, reservoir property and well completion quality are the two key factors determining the shale gas economics. The two key factors are strongly depending on shale lithofacies. On the basis of inorganic mineralogy theory, all available thin section, X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectrometer (EDS) data were used to assist lithofacies analysis. Gamma ray (GR), acoustic (AC), bulk density (RHOB), neutron porosity (NPHI) and photoelectric absorption cross-section index (PE) were selected for log response analysis of various minerals. Reservoir representative equation was created constrained by quantitative core analysis results, and matrix mineral percentage of quartz, carbonate, feldspar and pyrite were calculated to classify shale lithofacies. Considering the horizontal continuity of seismic data, rock physics model was built, and acoustic impedance integrated with core data and log data was used to predict the horizontal distribution of different lithofacies. The results indicate that: (1) nine lithofacies can be categorized in Duvernay shale, (2) the horizontal distribution of different lithofacies is quite diversified, siliceous shale mainly occurs in Simonette area, calcareous shale is prone to develop in the vicinity of reef, while calcareous-siliceous shale dominates in Willesdon Green area.

Structural and Sequence Stratigraphic Analysis of the Onshore Nile Delta, Egypt.

NASA Astrophysics Data System (ADS)

Barakat, Moataz; Dominik, Wilhelm

2010-05-01

The Nile Delta is considered the earliest known delta in the world. It was already described by Herodotus in the 5th Century AC. Nowadays; the Nile Delta is an emerging giant gas province in the Middle East with proven gas reserves which have more than doubled in size in the last years. The Nile Delta basin contains a thick sedimentary sequence inferred to extend from Jurassic to recent time. Structural styles and depositional environments varied during this period. Facies architecture and sequence stratigraphy of the Nile Delta are resolved using seismic stratigraphy based on (2D seismic lines) including synthetic seismograms and tying in well log data. Synthetic seismograms were constructed using sonic and density logs. The combination of structural interpretation and sequence stratigraphy of the development of the basin was resolved. Seven chrono-stratigraphic boundaries have been identified and correlated on seismic and well log data. Several unconformity boundaries also identified on seismic lines range from angular to disconformity type. Furthermore, time structure maps, velocity maps, depth structure maps as well as Isopach maps were constructed using seismic lines and log data. Several structural features were identified: normal faults, growth faults, listric faults, secondary antithetic faults and large rotated fault blocks of manly Miocene age. In some cases minor rollover structures could be identified. Sedimentary features such as paleo-channels were distinctively recognized. Typical Sequence stratigraphic features such as incised valley, clinoforms, topsets, offlaps and onlaps are identified and traced on the seismic lines allowing a good insight into sequence stratigraphic history of the Nile Delta most especially in the Miocene to Pliocene clastic sedimentary succession.

Continental-scale magmatic carbon dioxide seepage recorded by dawsonite in the Bowen-Gunnedah-Sydney basin system, eastern Australia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, J.C.; Bai, G.P.; Hamilton, P.J.

1995-07-03

Dawsonite, NaAlCO{sub 3}(OH){sub 2}, is widespread as a cement, replacement, and cavity filling in Permo-Triassic sedimentary rocks of the Bowen-Gunnedah-Sydney basin system eastern Australia. The origin of dawsonite in these rocks was studied by petrographic and stable isotope analysis. Dawsonite {delta}{sup 13}C (PDB) values range from {minus}4.0 to +4.1{per_thousand} and are remarkably consistent throughout the Bowen-Gunnedah-Sydney basin system. These values indicate either a marine carbonate or magmatic source for carbon in the dawsonite. A magmatic carbon source is considered more likely on the basis that (1) evidence of and the cause for widespread marine carbonate dissolution in the sedimentary successionsmore » are not apparent, (2) dawsonite is widespread in both marine and nonmarine facies, (3) the region has been the site of major igneous activity, (4) other dawsonite deposits of similar carbon isotopic composition are linked to igneous activity, and (5) magmatic CO{sub 2} accumulations are known in parts of the Bowen-Gunnedah-Sydney basin system. The timing of igneous activity in the Bowen Basin constrains the timing of dawsonite formation in the Bowen-Gunnedah-Sydney basin system to the Tertiary, consistent with textural relationships, which indicate that dawsonite formed late during the burial history of the Permo-triassic sequences. The distribution and interpreted origin of dawsonite implies magmatic CO{sub 2} seepage in the Bowen-Gunnedah-Sydney basin system on a continental scale.« less

Sedimentary record of a fluctuating ice margin from the Pennsylvanian of western Gondwana: Paraná Basin, southern Brazil

NASA Astrophysics Data System (ADS)

Vesely, Fernando F.; Trzaskos, Barbara; Kipper, Felipe; Assine, Mario Luis; Souza, Paulo A.

2015-08-01

The Paraná Basin is a key locality in the context of the Late Paleozoic Ice Age (LPIA) because of its location east of the Andean proto-margin of Gondwana and west of contiguous interior basins today found in western Africa. In this paper we document the sedimentary record associated with an ice margin that reached the eastern border of the Paraná Basin during the Pennsylvanian, with the aim of interpreting the depositional environments and discussing paleogeographic implications. The examined stratigraphic succession is divided in four stacked facies associations that record an upward transition from subglacial to glaciomarine environments. Deposition took place during deglaciation but was punctuated by minor readvances of the ice margin that deformed the sediment pile. Tillites, well-preserved landforms of subglacial erosion and glaciotectonic deformational structures indicate that the ice flowed to the north and northwest and that the ice margin did not advance far throughout the basin during the glacial maximum. Consequently, time-equivalent glacial deposits that crop out in other localities of eastern Paraná Basin are better explained by assuming multiple smaller ice lobes instead of one single large glacier. These ice lobes flowed from an ice cap covering uplifted lands now located in western Namibia, where glacial deposits are younger and occur confined within paleovalleys cut onto the Precambrian basement. This conclusion corroborates the idea of a topographically-controlled ice-spreading center in southwestern Africa and does not support the view of a large polar ice sheet controlling deposition in the Paraná Basin during the LPIA.

JACK CREEK BASIN, MONTANA.

USGS Publications Warehouse

Kiilsgaard, Thor H.; Van Noy, Ronald M.

1984-01-01

A mineral survey of the Jack Creek basin area in Montana revealed that phosphate rock underlies the basin. The phosphate rock is in thin beds that dip steeply and are broken and offset by faults. These features plus the rugged topography of the region would make mining difficult; however, this study finds the area to have a probable mineral-resource potential for phosphate. Sedimentary rock formations favorable for oil and gas also underlie the basin. No oil or gas has been produced from the basin or from nearby areas in southwestern Montana, but oil and gas have been produced from the same favorable formations elsewhere in Montana. The possibility of oil and gas being produced from the basin is slight but it cannot be ignored.

Crustal structure and tectonic deformation of the southern Ecuadorian margin

NASA Astrophysics Data System (ADS)

Calahorrano, Alcinoe; Collot, Jean-Yves; Sage, Françoise; Ranero, César R.

2010-05-01

Multichannel seismic lines acquired during the SISTEUR cruise (2000) provide new constraints on the structure and deformation of the subduction zone at the southern Ecuadorian margin, from the deformation front to the continental shelf of the Gulf of Guayaquil. The pre-stack depth migrated images allows to characterise the main structures of the downgoing and overriding plates and to map the margin stratigraphy in order to propose a chronology of the deformation, by means of integrating commercial well data and industry seismic lines located in the gulf area. The 100-km-long seismic lines show the oceanic Nazca plate underthrusting the South American plate, as well as the subduction channel and inter-plate contact from the deformation front to about 90 km landward and ~20 km depth. Based on seismic structure we identify four upper-plate units, consisting of basement and overlaying sedimentary sequences A, B and C. The sedimentary cover varies along the margin, being few hundreds of meters thick in the lower and middle slope, and ~2-3 km thick in the upper slope. Exceptionally, a ~10-km -thick basin, here named Banco Peru basin, is located on the upper slope at the southernmost part of the gulf. This basin seems to be the first evidence of the Gulf of Guayaquil opening resulting from the NE escaping of the North Andean Block. Below the continental shelf, thick sedimentary basins of ~6 to 8 km occupy most of the gulf area. Tectonic deformation across most of the upper-plate is dominated by extensional regime, locally disturbed by diapirism. Compression evidences are restricted to the deformation front and surrounding areas. Well data calibrating the seismic profiles indicate that an important portion of the total thickness of the sedimentary coverage of the overriding plate are Miocene or older. The data indicate the extensional deformation resulting from the NE motion of the North Andean Block and the opening of the Gulf of Guayaquil, evolves progressively in age from the southern edge of the gulf near Banco Peru, where main subsidence seems to be Miocene or older, toward the northern limit, where high subsidence rates are early Pleistocene.

Geology and physiography of the continental margin north of Alaska and implications for the origin of the Canada Basin

USGS Publications Warehouse

Grantz, Arthur; Eittreim, Stephen L.; Whitney, O.T.

1979-01-01

The continental margin north of Alaska is of Atlantic type. It began to form probably in Early Jurassic time but possibly in middle Early Cretaceous time, when the oceanic Canada Basin of the Arctic Ocean is thought to have opened by rifting about a pole of rotation near the Mackenzie Delta. Offsets of the rift along two fracture zones are thought to have divided the Alaskan margin into three sectors of contrasting structure and stratigraphy. In the Barter Island sector on the east and the Chukchi sector on the west the rift was closer to the present northern Alaska mainland than in the Barrow sector, which lies between them. In the Barter Island and Chukchi sectors the continental shelf is underlain by prisms of clastic sedimentary rocks that are inferred to include thick sections of Jurassic and Neocomian (lower Lower Cretaceous) strata of southern provenance. In the intervening Barrow sector the shelf is underlain by relatively thin sections of Jurassic and Neocomian strata derived from northern sources that now lie beneath the outer continental shelf. The rifted continental margin is overlain by a prograded prism of Albian (upper Lower Cretaceous) to Tertiary clastic sedimentary rocks that comprises the continental terrace of the western Beaufort and northern Chukchi Seas. On the south the prism is bounded by Barrow arch, which is a hingeline between the northward-tilted basement surface beneath the continental shelf of the western Beaufort Sea and the southward-tilted Arctic Platform of northern Alaska. The Arctic platform is overlain by shelf clastic and carbonate strata of Mississippian to Cretaceous age, and by Jurassic and Cretaceous clastic strata of the Colville foredeep. Both the Arctic platform and Colville foredeep sequences extend from northern Alaska beneath the northern Chukchi Sea. At Herald fault zone in the central Chukchi Sea they are overthrust by more strongly deformed Cretaceous to Paleozoic sedimentary rocks of Herald arch, which trends northwest from Cape Lisburne. Hope basin, an extensional intracontinental sedimentary basin of Tertiary age, underlies the Chukchi Sea south of Herald arch.

Large Sanjiang basin groups outside of the Songliao Basin Meso-Senozoic Tectonic-sediment evolution and hydrocarbon accumulation

NASA Astrophysics Data System (ADS)

Zheng, M.; Wu, X.

2015-12-01

The basis geological problem is still the bottleneck of the exploration work of the lager Sanjiang basin groups. In general terms, the problems are including the prototype basins and basin forming mechanism of two aspects. In this paper, using the field geological survey and investigation, logging data analysis, seismic data interpretation technical means large Sanjiang basin groups and basin forming mechanism of the prototype are discussed. Main draw the following conclusions： 1. Sanjiang region group-level formation can be completely contrasted. 2. Tension faults, compressive faults, shear structure composition and structure combination of four kinds of compound fracture are mainly developed In the study area. The direction of their distribution can be divided into SN, EW, NNE, NEE, NNW, NWW to other groups of fracture. 3. Large Sanjiang basin has the SN and the EW two main directions of tectonic evolution. Cenozoic basins in Sanjiang region in group formation located the two tectonic domains of ancient Paleo-Asian Ocean and the Pacific Interchange. 4. Large Sanjiang basin has experienced in the late Mesozoic tectonic evolution of two-stage and nine times. The first stage, developmental stage basement, they are ① Since the Mesozoic era and before the Jurassic; ② Early Jurassic period; The second stage, cap stage of development, they are ③ Late Jurassic depression developmental stages of compression; ④ Early Cretaceous rifting stage; ⑤ depression in mid-Early Cretaceous period; ⑥ tensile Early Cretaceous rifting stage; ⑦ inversion of Late Cretaceous tectonic compression stage; ⑧ Paleogene - Neogene; ⑨ After recently Ji Baoquan Sedimentary Ridge. 5. Large Sanjiang basin group is actually a residual basin structure, and Can be divided into left - superimposed (Founder, Tangyuan depression, Hulin Basin), residual - inherited type (Sanjiang basin), residual - reformed (Jixi, Boli, Hegang basin). there are two developed depression and the mechanism of rifting. 6. Sanjiang Basin Suibin Depression, Tangyuan depression, Jixi Cretaceous Tangyuan and Fangzheng rift is the key for further exploration. Yishu graben is a large core of Sanjiang region to find oil, and Paleogene basin is the focus of the external layer system exploration.

Geological Influences on Bedrock Topography and East Antarctic Ice Sheet Dynamics in the Wilkes Subglacial Basin

NASA Astrophysics Data System (ADS)

Ferraccioli, F.; Armadillo, E.; Young, D. A.; Blankenship, D. D.; Jordan, T. A.; Balbi, P.; Bozzo, E.; Siegert, M. J.

2014-12-01

The Wilkes Subglacial Basin (WSB) extends for 1,400 km from George V Land into the interior of East Antarctica and hosts several major glaciers that drain a large sector of the East Antarctic Ice Sheet (EAIS). This region is of key significance for the long-term stability of the ice sheet in East Antarctica, as it lies well below sea level and its bedrock deepens inland, making it potentially prone to marine ice sheet instability, much like areas of the West Antarctic Ice Sheet (WAIS) that are presently experiencing significant mass loss. We present new enhanced potential field images of the WSB combined with existing radar imaging to study geological controls on bedrock topography and ice flow regimes in this key sector of the ice sheet. These images reveal mayor Precambrian and Paleozoic basement faults that exert tectonic controls both on the margins of the basin and its sub-basins. Several major sub-basins can be recognised: the Eastern Basin, the Central Basins and the Western Basins. Using ICECAP aerogeophysical data we show that these tectonically controlled interior basins connect to newly identified basins underlying the Cook Ice Shelf region. This connection implies that any ocean-induced changes at the margin of the EAIS could potentially propagate rapidly further into the interior. With the aid of simple magnetic and gravity models we show that the WSB does not presently include major post Jurassic sedimentary infill. Its bedrock geology is highly variable and includes Proterozoic basement, Neoproterozoic and Cambrian sediments, intruded by Cambrian arc rocks, and cover rocks formed by Beacon sediments intruded by Jurassic Ferrar sills. Enhanced ice flow in this part of the EAIS occurs therefore in a area of mixed and spatially variable bedrock geology. This contrasts with some regions of the WAIS where more extensive sedimentary basins may represent a geological template for the onset and maintenance of fast glacial flow.

A 2D numerical approach to predict sedimentary deposits of submarine gravity flows based on a Saint-Venant model with density variation effects. Example of Annot Basin (SE, France)

NASA Astrophysics Data System (ADS)

Le Solleuz, A.; Golfier, F.; Verdon, N.

2010-12-01

Submarine gravity flows, so called hyperpycnal currents, are very fast and can be induced by a major river flood or submarine slope instability. Sedimentary deposits, due to the stacking of these events (2 or 3 per year) during millions years can constitute a very good reservoir. However, predicting the evolution of such a sedimentary filling over geological time scales is a tremendous task. Especially, the ability to predict the starting of avalanches and the knowledge of mechanisms which drive erosion and sedimentary deposits are very poor. We focus in this study on the Annot sandstones system in the Alps (SE of France) which developed a very large tertiary deep sea fan well exposed and well studied in a sedimentary point of view (tectonics, sources, facies distribution, duration, etc.). We propose here to simulate the spatial distribution of these high-concentrated submarine gravity flows taking into account density variations of the sediment-water mixture. The main difficulty of our approach consists in simulating thousands events in a reasonable computational time. The ultimate goal is to apply this numerical model to the configuration of Annot Basin and to compare our results to the different existing deposits. To understand the physical processes that drive these hyperpycnal flows (high concentrated turbidites), many researchers focused on an accurate description of the phenomenon, for example by solving the 3D Navier-Stokes equations coupled with a mass transport equation. But, if such approaches are well-suited for the description of a single event, they are too computationally expensive to predict the sedimentary deposit over millions of years, i.e. over millions of events. We propose here an adapted version of the multilayer Saint-Venant model. It allows obtaining results with a low computational time (i.e. well-suited for millions of flows). Given the difference of sediment concentration between the head and the tail of a turbidite, we have derived a new version of these classical equations based on the variation of the fluid density. The resulting system, which takes into account the variation of density along the flow direction, is thus coupled to a density transport equation. Moreover, due to the high density stratification in the fluid flow along the vertical direction, a multilayer approach is adopted. In essence, it consists in discretizing the flow thickness into different layers and hence, considering a Saint-Venant formulation associated to each vertical layer. Numerical implementation of the model is discussed and the above-mentioned theoretical extension of the classical Saint-Venant model is validated through a comparison with benchmarks. The impact of the variable density assumption is investigated. And finally, we apply this 2D model to a realistic geological configuration, the Annot Basin.

Neogene deformation of thrust-top Rzeszów Basin (Outer Carpathians, Poland)

NASA Astrophysics Data System (ADS)

Uroda, Joanna

2015-04-01

The Rzeszów Basin is a 220 km2 basin located in the frontal part of Polish Outer Carpathians fold-and-thrust belt. Its sedimentary succession consist of ca. 600 m- thick Miocene evaporates, litoral and marine sediments. This basin developed between Babica-Kąkolówka anticline and frontal thrust of Carpathian Orogen. Rzeszów thrust-top basin is a part of Carpathian foreland basin system- wedge-top depozone. The sediments of wedge -top depozone were syntectonic deformed, what is valuable tool to understand kinematic history of the orogen. Analysis of field and 3D seismic reflection data showed the internal structure of the basin. Seismic data reveal the presence of fault-bend-folds in the basement of Rzeszów basin. The architecture of the basin - the presence of fault-releated folds - suggest that the sediments were deformed in last compressing phase of Carpathian Orogen deformation. Evolution of Rzeszów Basin is compared with Bonini et.al. (1999) model of thrust-top basin whose development is controlled by the kinematics of two competing thrust anticlines. Analysis of seismic and well data in Rzeszów basin suggest that growth sediments are thicker in south part of the basin. During the thrusting the passive rotation of the internal thrust had taken place, what influence the basin fill architecture and depocentre migration opposite to thrust propagation. Acknowledgments This study was supported by grant No 2012/07/N/ST10/03221 of the Polish National Centre of Science "Tectonic activity of the Skole Nappe based on analysis of changes in the vertical profile and depocentre migration of Neogene sediments in Rzeszów-Strzyżów area (Outer Carpathians)". Seismic data by courtesy of the Polish Gas and Oil Company. References Bonini M., Moratti G., Sani F., 1999, Evolution and depocentre migration in thrust-top basins: inferences from the Messinian Velona Basin (Northern Apennines, Italy), Tectonophysics 304, 95-108.

Optimization of Well Configuration for a Sedimentary Enhanced Geothermal Reservoir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Mengnan; Cho, JaeKyoung; Zerpa, Luis E.

The extraction of geothermal energy in the form of hot water from sedimentary rock formations could expand the current geothermal energy resources toward new regions. From previous work, we observed that sedimentary geothermal reservoirs with relatively low permeability would require the application of enhancement techniques (e.g., well hydraulic stimulation) to achieve commercial production/injection rates. In this paper we extend our previous work to develop a methodology to determine the optimum well configuration that maximizes the hydraulic performance of the geothermal system. The geothermal systems considered consist of one vertical well doublet system with hydraulic fractures, and three horizontal well configurationsmore » with open-hole completion, longitudinal fractures and transverse fractures, respectively. A commercial thermal reservoir simulation is used to evaluate the geothermal reservoir performance using as design parameters the well spacing and the length of the horizontal wells. The results obtained from the numerical simulations are used to build a response surface model based on the multiple linear regression method. The optimum configuration of the sedimentary geothermal systems is obtained from the analysis of the response surface model. The proposed methodology is applied to a case study based on a reservoir model of the Lyons sandstone formation, located in the Wattenberg field, Denver-Julesburg basin, Colorado.« less

Refinement of Regional Distance Seismic Moment Tensor and Uncertainty Analysis for Source-Type Identification

DTIC Science & Technology

2014-09-02

release; distribution is unlimited. rock zone which provides a pathway for formation fluids, natural gas and crude oil from deeper strata that are... southeast Louisiana (Figure 21). It is a part of the Gulf Coast salt basin which exhibits many salt structures formed by upward flow of sedimentary salt...primarily, evaporites) on account of low density of salt and overburden pressures caused by younger sedimentary deposits (Beckman and Williamson, 1990

Contact zone permeability at intrusion boundaries: New results from hydraulic testing and geophysical logging in the Newark Rift Basin, New York, USA

USGS Publications Warehouse

Matter, J.M.; Goldberg, D.S.; Morin, R.H.; Stute, M.

2006-01-01

Hydraulic tests and geophysical logging performed in the Palisades sill and the underlying sedimentary rocks in the NE part of the Newark Rift Basin, New York, USA, confirm that the particular transmissive zones are localized within the dolerite-sedimentary rock contact zone and within a narrow interval below this contact zone that is characterized by the occurrence of small layers of chilled dolerite. Transmissivity values determined from fluid injection, aquifer testing, and flowmeter measurements generally fall in the range of 8.1E-08 to 9.95E-06 m2/s and correspond to various scales of investigation. The analysis of acoustic and optical BHTV images reveals two primary fracture sets within the dolerite and the sedimentary rocks - subhorizontal fractures, intersected by subvertical ones. Despite being highly fractured either with subhorizontal, subvertical or both fracture populations, the dolerite above and the sedimentary rocks below the contact zone and the zone with the layers of chilled dolerite are significantly less conductive. The distribution of the particular conductive intervals is not a function of the two dominant fracture populations or their density but rather of the intrusion path of the sill. The intrusion caused thermal fracturing and cracking of both formations, resulting in higher permeability along the contact zone. ?? Springer-Verlag 2005.

A Mesozoic orogenic cycle from post-collision to subduction in the southwestern Korean Peninsula: New structural, geochemical, and chronological evidence

NASA Astrophysics Data System (ADS)

Park, Seung-Ik; Kwon, Sanghoon; Kim, Sung Won; Hong, Paul S.; Santosh, M.

2018-05-01

The Early to Middle Mesozoic basins, distributed sporadically over the Korean Peninsula, preserve important records of the tectonic history of some of the major orogenic belts in East Asia. Here we present a comprehensive study of the structural, geochemical, geochronological, and paleontological features of a volcano-sedimentary package, belonging to the Oseosan Volcanic Complex of the Early to Middle Mesozoic Chungnam Basin, within the Mesozoic subduction-collision orogen in the southwestern Korean Peninsula. The zircon U-Pb data from rhyolitic volcanic rocks of the complex suggest Early to Middle Jurassic emplacement age of ca. 178-172 Ma, harmonious with plant fossil taxa found from the overlying tuffaceous sedimentary rock. The geochemical data for the rhyolitic volcanic rocks are indicative of volcanic arc setting, implying that the Chungnam Basin has experienced an intra-arc subsidence during the basin-expanding stage by subduction of the Paleo-Pacific (Izanagi) Plate. The Jurassic arc-related Oseosan Volcanic Complex was structurally stacked by the older Late Triassic to Early Jurassic post-collisional basin-fill of the Nampo Group by the Jangsan fault during basin inversion. The Late Jurassic to Early Cretaceous K-feldspar and illite K-Ar ages marked the timing of inversion tectonics, contemporaneous with the magmatic quiescence in the southern Korean Peninsula, likely due to flat-lying or low-angle subduction. The basin evolution history preserved in the Mesozoic Chungnam Basin reflects a Mesozoic orogenic cycle from post-collision to subduction in the southwestern Korean Peninsula. This, in turn, provides a better understanding of the spatial and temporal changes in Mesozoic tectonic environments along the East Asian continental margin.

Tectonic setting of the Taubaté Basin (Southeastern Brazil): Insights from regional seismic profiles and outcrop data

NASA Astrophysics Data System (ADS)

Cogné, Nathan; Cobbold, Peter R.; Riccomini, Claudio; Gallagher, Kerry

2013-03-01

In southeastern Brazil, a series of onshore Tertiary basins provides good evidence for post-rift tectonic activity. So as better to constrain their tectonic setting, we have revisited outcrops in the Taubaté and Resende basins and have reinterpreted 11 seismic profiles of the Taubaté Basin. Where Eocene to Oligocene strata crop out, syn-sedimentary faults are common and their senses of slip are mainly normal. In contrast, for two outcrops in particular, where syn-sedimentary faults have put Precambrian crystalline basement against Eocene strata, senses of slip are strongly left-lateral, as well as normal. Thus we distinguish between thin-skinned and thick-skinned faulting. Furthermore, at four outcrops, Precambrian basement has overthrust Tertiary or Quaternary strata. On the seismic profiles, basal strata onlap basement highs. Structures and stratigraphic relationships are not typical of a rift basin. Although normal faults are common, they tend to be steeply dipping, their stratigraphic offsets are small (tens of metres) and the faults do not bound large stratigraphic wedges or tilted blocks. At the edges of the basin, Eocene or Oligocene strata dip basinward, have been subject to exhumation, and in places form gentle anticlines, so that we infer post-Oligocene inversion. We conclude that, after an earlier phase of deformation, probably during the Late Cretaceous, the Taubaté Basin formed under left-lateral transtension during the Palaeogene, but was subject to right-lateral transpression during the Neogene. Thus the principal directions of stress varied in time. Because they did so consistently with those of the adjacent regions, as well as those of the Incaic and Quechua phases of Andean orogeny, we argue that the Tertiary basins of southeast Brazil have resulted from reactivation of Precambrian shear zones under plate-wide stress.

The location and nature of the Telemzan High Ghadames basin boundary in southern Tunisia based on gravity and magnetic anomalies

NASA Astrophysics Data System (ADS)

Gabtni, H.; Jallouli, C.; Mickus, K. L.; Zouari, H.; Turki, M. M.

2006-03-01

Gravity and magnetic data were analyzed to add constraints on the location and nature of the Telemzan-Ghadames boundary (TGB) and structure of the Ghadames basin in southern Tunisia. TGB is the boundary between the thick sedimentary cover of the intracratonic Ghadames basin to the south and the thin sedimentary cover of the Saharan platform to the north. The upward continuation of the Bouguer gravity anomalies showed that the TGB is a regional geophysical feature that may have controlled the amount of sediment being deposited both north and south of the boundary and the tectonic environment in the region since Paleozoic time. To emphasize the shorter wavelength gravity and magnetic anomalies, a series of gray scale images of the directional horizontal gradients were constructed that determined a series of previously unknown east-west-trending gravity and magnetic anomalies south of 31.6°N that correspond to lineaments seen on a Landsat 7 image and the location of the TGB. Also, an edge-enhancement analysis illustrated the same linear gravity anomalies and showed the subbasins and uplifts within the Ghadames basin had source depths of between 0.5 and 3.4 km. A north-south trending gravity model showed that the TGB is a relatively gradual feature (possibly basement stepped down by relatively low-displacement faulting) controlling the subsidence of the main Ghadames basin and confirms the edge-enhancement analysis that subbasin S3 and uplift U1 are the main structural features within the Ghadames basin. The knowledge of basement architecture of the Ghadames basin is important for future petroleum exploration within this intracratonic basin.

Origin of the Squantum 'Tillite', Massachusetts, USA: Modern Analogs and Implications for Neoproterozoic Climate Models

NASA Astrophysics Data System (ADS)

Carto, S. L.; Eyles, N.

2009-05-01

A central challenge to the 'Snowball Earth' hypothesis is whether the sedimentary rocks deposited during the Neoproterozoic (c. 750-570 Ma) are glacial tillites that accumulated under global ice sheets during this era. This uncertainty stems from the fact that diamictites are not uniquely glacial in origin, as the slumping and mixing of sediment downslope can also produce diamictites. A key deposit in this debate is the Squantum 'tillite' (ca. 595-570 Ma) preserved in the Boston Basin in Massachusetts, USA, which originated as an arc- related basin within the Avalon island arc terrane during the Neoproterozoic. Detailed field examinations of the Squantum by the author suggest that it owes its origin to the downslope transport of large volumes of unstable volcanic and sedimentary debris from steep basin margin slopes. No evidence of a glacial environment was identified. Thin-section analysis of this deposit has revealed a significant volcanic influence on sedimentation in the form of hitherto unrecognized volcanic lapilli tuff horizons and turbidites consisting of reworked ash in strata associated with Squantum diamictite. These results point to deposition related to tectonic activity and basin development rather than severe global glacial conditions. In light of these results, the Squantum diamictite was compared to the volcaniclastic mass flows deposits exposed along the active Lesser Antilles Arc in the Caribbean. Many of these flows are transported into the adjacent Grenada back-arc Basin by debris flows and turbidity currents resulting in the deposition of volcaniclastic conglomerates, diamictites and thin ash turbidites. Gross stratigraphic and sedimentological similarities of the mass flow facies in the Caribbean can be identified with the Squantum deposits, suggesting that appropriate depositional analogs for the Squantum can be found along the Lesser Antilles Arc. The significance of these results is that they emphasize the importance of detailed field examination of deposits uncritically labeled as Neoproterozoic 'tillites' by paleoclimate modelers.

Airborne full tensor magnetic gradiometry surveys in the Thuringian basin, Germany

NASA Astrophysics Data System (ADS)

Queitsch, M.; Schiffler, M.; Goepel, A.; Stolz, R.; Meyer, M.; Meyer, H.; Kukowski, N.

2013-12-01

In this contribution we introduce a newly developed fully operational full tensor magnetic gradiometer (FTMG) instrument based on Superconducting Quantum Interference Devices (SQUIDs) and show example data acquired in 2012 within the framework of the INFLUINS (Integrated Fluid Dynamics in Sedimentary basins) project. This multidisciplinary project aims for a better understanding of movements and interaction between shallow and deep fluids in the Thuringian Basin in the center of Germany. In contrast to mapping total magnetic field intensity (TMI) in conventional airborne magnetic surveys for industrial exploration of mineral deposits and sedimentary basins, our instrument measures all components of the magnetic field gradient tensor using highly sensitive SQUID gradiometers. This significantly constrains the solutions of the inverse problem. Furthermore, information on the ratio between induced and remanent magnetization is obtained. Special care has been taken to reduce motion noise while acquiring data in airborne operation. Therefore, the sensors are mounted in a nonmagnetic and aerodynamically shaped bird made of fiberglas with a high drag tail which stabilizes the bird even at low velocities. The system is towed by a helicopter and kept at 30m above ground during data acquisition. Additionally, the system in the bird incorporates an inertial unit for geo-referencing and enhanced motion noise compensation, a radar altimeter for topographic correction and a GPS system for high precision positioning. Advanced data processing techniques using reference magnetometer and inertial unit data result in a very low system noise of less than 60 pT/m peak to peak in airborne operation. To show the performance of the system we present example results from survey areas within the Thuringian basin and along its bordering highlands. The mapped gradient tensor components show a high correlation to existing geologic maps. Furthermore, the measured gradient components indicate that some of the observed magnetic anomalies have a strong remanent magnetization. One example of interpretation of the acquired data of a magnetic anomaly related to a larger gabbro formation is presented.

Mechanical stratification of autochthonous salt: Implications from basin-scale numerical models of rifted margin salt tectonics

NASA Astrophysics Data System (ADS)

Ings, Steven; Albertz, Markus

2014-05-01

Deformation of salt and sediments owing to the flow of weak evaporites is a common phenomenon in sedimentary basins worldwide, and the resulting structures and thermal regimes have a significant impact on hydrocarbon exploration. Evaporite sequences ('salt') of significant thickness (e.g., >1km) are typically deposited in many cycles of seawater inundation and evaporation in restricted basins resulting in layered autochthonous evaporite packages. However, analogue and numerical models of salt tectonics typically treat salt as a homogeneous viscous material, often with properties of halite, the weakest evaporite. In this study, we present results of two-dimensional plane-strain numerical experiments designed to illustrate the effects of variable evaporite viscosity and embedded frictional-plastic ('brittle') sediment layers on the style of salt flow and associated deformation of the sedimentary overburden. Evaporite viscosity is a first-order control on salt flow rate and the style of overburden deformation. Near-complete evacuation of low-viscosity salt occurs beneath expulsion basins, whereas significant salt is trapped when viscosity is high. Embedded frictional-plastic sediment layers (with finite yield strength) partition salt flow and develop transient contractional structures (folds, thrust faults, and folded faults) in a seaward salt-squeeze flow regime. Multiple internal sediment layers reduce the overall seaward salt flow during sediment aggradation, leaving more salt behind to be re-mobilized during subsequent progradation. This produces more seaward extensive allochthonous salt sheets. If there is a density difference between the embedded layers and the surrounding salt, then the embedded layers 'fractionate' during deformation and either float to the surface or sink to the bottom (depending on density), creating a thick zone of pure halite. Such a process of 'buoyancy fractionation' may partially explain the apparent paradox of layered salt in autochthonous salt basins and thick packages of pure halite in allochthonous salt sheets.

Visayan Basin - the birthplace of Philippine petroleum exploration revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rillera, F.G.; Durkee, E.F.

1994-07-01

Petroleum exploration in the Philippines has its roots in the Visayan Basin in the central Philippines. This is a Tertiary basin with up to 30,000 ft of sedimentary fill. With numerous surface oil and gas manifestations known as early as 1888, the area was the site of the first attempts to establish commercial petroleum production in the country. Over the past 100 years, more than 200 wells have been drilled in the basin. Several of these have yielded significant oil and gas shows. Production, albeit noncommercial in scale, has been demonstrated to be present in some places. A review ofmore » past exploration data reveals that many of the earlier efforts failed due to poorly located tests from both structural and stratigraphic standpoints. Poor drilling and completion technology and lack of funding compounded the problems of early explorationists. Because of this, the basin remains relatively underexplored. A recent assessment by COPLEX and E.F. Durkee and Associates demonstrates the presence of many untested prospects in the basin. These prospects may contain recoverable oil and gas potential on the order of 5 to 10 MMBO onshore and 25 to 100 MMBO offshore. With new exploration ideas, innovative development concepts, and the benefit of modern technology, commercial oil and gas production from the basin may yet be realized.« less

Observations of basin ground motions from a dense seismic array in San Jose, California

USGS Publications Warehouse

Frankel, A.; Carver, D.; Cranswick, E.; Bice, T.; Sell, R.; Hanson, S.

2001-01-01

We installed a dense array of 41 digital seismographs in San Jose, California, to evaluate in detail the effects of a deep sedimentary basin and shallow sedimentary deposits on earthquake ground motions. This urban array is located near the eastern edge of the Santa Clara Valley and spans the Evergreen sedimentary basin identified by gravity data. Average station spacing is 1 km, with three stations initially spaced 110 m apart. Despite the high-noise urban environment, the stations of the array successfully triggered on and recorded small local earthquakes (M 2.5-2.8 at 10-25 km distance) and larger regional events such as the M 5.0 Bolinas earthquake (90 km distance), M 4.6-5.6 earthquakes near Mammoth Lakes (270 km distance), M 4.9-5.6 events in western Nevada (420 km distance) and the M 7.1 Hector Mine earthquake (590 km distance). Maps of spectral ratios across the array show that the highest amplitudes in all frequency bands studied (0.125-8 Hz) are generally observed at stations farther from the eastern edge of the Santa Clara Valley. Larger spectral amplitudes are often observed above the western edge of the Evergreen Basin. Snapshots of the recorded wavefield crossing the array for regional events to the east reveal that large, low-frequency (0.125-0.5 Hz) arrivals after the S-wave travel from south to north across the array. A moving-window, cross-correlation analysis finds that these later arrivals are surface waves traveling from the south. The timing and propagation direction of these arrivals indicates that they were likely produced by scattering of incident S waves at the border of the Santa Clara Valley to the south of the array. It is remarkable that the largest low-frequency phases at many of the valley sites for regional events to the east are basin surface waves coming from a direction about 70 degrees different from that of the epicenters. Basin surface waves emanating from the eastern edge of the valley are also identified by the cross-correlation analysis.

Constraints on the history and topography of the Northeastern Sierra Nevada from a Neogene sedimentary basin in the Reno-Verdi area, Western Nevada

USGS Publications Warehouse

Trexler, James; Cashman, Patricia; Cosca, Michael

2012-01-01

Neogene (Miocene–Pliocene) sedimentary rocks of the northeastern Sierra Nevada were deposited in small basins that formed in response to volcanic and tectonic activity along the eastern margin of the Sierra. These strata record an early phase (ca. 11–10 Ma) of extension and rapid sedimentation of boulder conglomerates and debrites deposited on alluvial fans, followed by fluvio-lacustrine sedimentation and nearby volcanic arc activity but tectonic quiescence, until ~ 2.6 Ma. The fossil record in these rocks documents a warmer, wetter climate featuring large mammals and lacking the Sierran orographic rain shadow that dominates climate today on the eastern edge of the Sierra. This record of a general lack of paleo-relief across the eastern margin of the Sierra Nevada is consistent with evidence presented elsewhere that there was not a significant topographic barrier between the Pacific Ocean and the interior of the continent east of the Sierra before ~ 2.6 Ma. However, these sediments do not record an integrated drainage system either to the east into the Great Basin like the modern Truckee River, or to the west across the Sierra like the ancestral Feather and Yuba rivers. The Neogene Reno-Verdi basin was one of several, scattered endorheic (i.e., internally drained) basins occupying this part of the Cascade intra-arc and back-arc area.

Allogenic controls on the fluvial architecture and fossil preservation of the Upper Triassic Ischigualasto Formation, NW Argentina

NASA Astrophysics Data System (ADS)

Colombi, Carina E.; Limarino, Carlos O.; Alcober, Oscar A.

2017-12-01

The Upper Triassic Ischigualasto Formation in NW Argentina was deposited in a fluvial system during the synrift filling of the extensional Ischigualasto-Villa Unión Basin. The expansive exposures of the fluvial architecture and paleosols provide a framework to reconstruct the paleoenvironmental evolution of this basin during the Upper Triassic using continental sequence stratigraphy. The Ischigualasto Formation deposition can be divided into seven sequential sedimentary stages: the 1) Bypass stage; 2) Confined low-accommodation stage; 3) Confined high accommodation stage; 4) Unstable-accommodation stage; 5) Unconfined high-accommodation stage; 6) Unconfined low-accommodation stage; and finally, 7) Unconfined high-accommodation stage. The sedimentary evolution of the Ischigualasto Formation was driven by different allogenic controls such as rises and falls in lake levels, local tectonism, subsidence, volcanism, and climate, which also produced modifications of the equilibrium profile of the fluvial systems. All of these factors result in different accommodations in central and flank areas of the basin, which led to different architectural configurations of channels and floodplains. Allogenic processes affected not only the sequence stratigraphy of the basin but also the vertebrate and plant taphocenosis. Therefore, the sequence stratigraphy can be used not only as a predictive tool related to fossil occurrence but also to understand the taphonomic history of the basin at each temporal interval.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bird, P.R.; Johns, C.C.; Clark-Lowes, D.D.

Western Turkey consists of a number of tectonic terranes joined together by a network of suture zones. The terranes originated as microcontinental plates that rifted away from the continental margins forming the northern and southern boundaries of the Tethyan sea. These micro-continents were united by a series of collisions beginning in the Late Triassic and ending in the Miocene, with the final closure of the Tethyan sea. The sedimentary cover of the microcontinents consists of Paleozoic and Mesozoic passive margin and rift basin sequences containing numerous potential source and reservoir intervals. Most of these sequences show affinities with Gondwanaland, withmore » the notable exception of the Istanbul nappe, which is strongly Laurasian in character. Forearc basin sequences were also deposited on the margins of the microcontinents during early Tertiary plate convergence. Ensuing continental collisions resulted in compressional deformation of sedimentary cover sequences. The intensity of deformation ranged from basin inversion producing numerous potential hydrocarbon traps, to large-scale overthrusting. Following continental suturing, continued compression in eastern Turkey has been accommodated since the Miocene by westward escape of continental lithosphere between the North and South Anatolian transform faults. Neotectonic pull-apart basins formed in response to these movements, accumulating large thicknesses of Miocene-Pliocene carbonates and clastic sediments. Potential reservoirs in the Neotectonic basins may be sourced either in situ or from underlying Paleozoic and Mesozoic source rocks that remain within the hydrocarbon generating window today.« less

Age, distribution, and stratigraphic relationship of rock units in the San Joaquin Basin Province, California: Chapter 5 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

USGS Publications Warehouse

Hosford Scheirer, Allegra; Magoon, Leslie B.

2008-01-01

The San Joaquin Basin is a major petroleum province that forms the southern half of California’s Great Valley, a 700-km-long, asymmetrical basin that originated between a subduction zone to the west and the Sierra Nevada to the east. Sedimentary fill and tectonic structures of the San Joaquin Basin record the Mesozoic through Cenozoic geologic history of North America’s western margin. More than 25,000 feet (>7,500 meters) of sedimentary rocks overlie the basement surface and provide a nearly continuous record of sedimentation over the past ~100 m.y. Further, depositional geometries and fault structures document the tectonic evolution of the region from forearc setting to strike-slip basin to transpressional margin. Sedimentary architecture in the San Joaquin Basin is complicated because of these tectonic regimes and because of lateral changes in depositional environment and temporal changes in relative sea level. Few formations are widespread across the basin. Consequently, a careful analysis of sedimentary facies is required to unravel the basin’s depositional history on a regional scale. At least three high-quality organic source rocks formed in the San Joaquin Basin during periods of sea level transgression and anoxia. Generated on the basin’s west side, hydrocarbons migrated into nearly every facies type in the basin, from shelf and submarine fan sands to diatomite and shale to nonmarine coarse-grained rocks to schist. In 2003, the U.S. Geological Survey (USGS) completed a geologic assessment of undiscovered oil and gas resources and future additions to reserves in the San Joaquin Valley of California (USGS San Joaquin Basin Province Assessment Team, this volume, chapter 1). Several research aims supported this assessment: identifying and mapping the petroleum systems, modeling the generation, migration, and accumulation of hydrocarbons, and defining the volumes of rock to be analyzed for additional resources. To better understand the three dimensional relationships between hydrocarbon source and reservoir rocks, we compiled a database consisting of more than 13,000 well picks and of one-mile resolution seismic grids. Both the well picks and the seismic grids characterize the depths to the top of key stratigraphic units. This database formed the basis of subsequent numerical modeling efforts, including the construction of a three- dimensional geologic model (Hosford Scheirer, this volume, chapter 7) and simulation of the petroleum systems in space and time (Peters, Magoon, Lampe, and others, this volume, chapter 12). To accomplish this modeling, we synthesized the age, geographic distribution, lithology, and petroleum characteristics of hydrocarbon source and reservoir rocks in the basin. The results of that synthesis are presented in this paper in the form of new stratigraphic correlation columns for the northern, central, and southern San Joaquin Valley (fig. 5.1; note that all figures are at the back of this report, following the References Cited). The stratigraphic relationships and ages published here draw heavily on published and unpublished studies of the San Joaquin Basin. The stratigraphy presented in each of the columns necessarily idealizes the subsurface geology over a relatively large area, instead of representing the specific geology at an individual well, oil and gas field, or outcrop. In this paper we present the background rationale for defining the geographic divisions of the basin (inset map, fig. 5.1), the paleontological time scales used for assigning absolute ages to rock units (figs. 5.2 and 5.3), and the supporting maps illustrating the geographic distribution of each rock type included in the stratigraphic column (figs. 5.4 through 5.64).

Research on Formation Mechanisms of Hot Dry Rock Resources in China

NASA Astrophysics Data System (ADS)

Wang, G.; Xi, Y.

2017-12-01

As an important geothermal resource, hot dry rock(HDR) reserves have been studied in many countries. HDR resources in China have huge capacity and have become one of the most important resources for the potential replacement of fossil fuels. However, HDR resources are difficult to develop and utilise. Technologies for use with HDR, such as high-temperature drilling, reservoir characterisation, reservoir fracturing, microseismic monitoring and high-temperature power stations, originate from the field of oil and drilling. Addressing how to take advantage of these developed technologies is a key factor in the development of HDR reserves. Based on the thermal crustal structure in China, HDR resources can be divided into four types: high radioactive heat production, sedimentary basin, modern volcano and the inner-plate active tectonic belt. The prospective regions of HDR resources are located in South Tibet, West Yunnan, the southeast coast of China, Bohai Rim, Songliao Basin and Guanzhong Basin. The related essential technologies are relatively mature, and the prospect of HDR power generation is promising. Therefore, analysing the formation mechanisms of HDR resources and promoting the transformation of technological achievements, large-scale development and the utilisation of HDR resources can be achieved in China.

Clustering and interpretation of local earthquake tomography models in the southern Dead Sea basin

NASA Astrophysics Data System (ADS)

Bauer, Klaus; Braeuer, Benjamin

2016-04-01

The Dead Sea transform (DST) marks the boundary between the Arabian and the African plates. Ongoing left-lateral relative plate motion and strike-slip deformation started in the Early Miocene (20 MA) and produced a total shift of 107 km until presence. The Dead Sea basin (DSB) located in the central part of the DST is one of the largest pull-apart basins in the world. It was formed from step-over of different fault strands at a major segment boundary of the transform fault system. The basin development was accompanied by deposition of clastics and evaporites and subsequent salt diapirism. Ongoing deformation within the basin and activity of the boundary faults are indicated by increased seismicity. The internal architecture of the DSB and the crustal structure around the DST were subject of several large scientific projects carried out since 2000. Here we report on a local earthquake tomography study from the southern DSB. In 2006-2008, a dense seismic network consisting of 65 stations was operated for 18 months in the southern part of the DSB and surrounding regions. Altogether 530 well-constrained seismic events with 13,970 P- and 12,760 S-wave arrival times were used for a travel time inversion for Vp, Vp/Vs velocity structure and seismicity distribution. The work flow included 1D inversion, 2.5D and 3D tomography, and resolution analysis. We demonstrate a possible strategy how several tomographic models such as Vp, Vs and Vp/Vs can be integrated for a combined lithological interpretation. We analyzed the tomographic models derived by 2.5D inversion using neural network clustering techniques. The method allows us to identify major lithologies by their petrophysical signatures. Remapping the clusters into the subsurface reveals the distribution of basin sediments, prebasin sedimentary rocks, and crystalline basement. The DSB shows an asymmetric structure with thickness variation from 5 km in the west to 13 km in the east. Most importantly, a well-defined body under the eastern part of the basin down to 18 km depth was identified by the algorithm. Considering its geometry and petrophysical signature, this unit is interpreted as prebasin sediments and not as crystalline basement. The seismicity distribution supports our results, where events are concentrated along boundaries of the basin and the deep prebasin sedimentary body.

Geology and Geophysical Surveys to Infer the Structure of the Upper San Pedro River Basin, Sonora, Mexico for Use in a Ground-Water-Flow Model

NASA Astrophysics Data System (ADS)

Pool, D.; Gray, F.; Callegary, J. B.

2005-05-01

Data on geology and geophysics in the San Pedro River Basin in Sonora, Mexico were combined to develop a three-dimensional conceptual model of the alluvial-fill aquifer in the basin that is being used to construct a regional ground-water-flow model. In Mexico, the headwater region of the river encompasses approximately 1,800 square kilometers of an ungaged catchment system. This feeds a 58 kilometer-long series of intermittent and perennial stream reaches in the United States that extend from just north of the international border to the town of St. David, Arizona. The river forms part of a north-south riparian corridor that provides habitat for more than 100 resident and 250 migratory bird species. Ground water in the basin is used extensively on both sides of the border and information on basin structure and composition will help to address questions regarding ground- and surface-water sustainability and planning. Interpretations of bedrock and alluvial-fill geometry indicate that a significant portion of the catchment area in Mexico is underlain by bedrock composed of highly indurated (compacted) Cretaceous sedimentary, volcanic, volcano-sedimentary, and granitic intrusive rocks. Aeromagnetic surveys were used to estimate depth to bedrock underlying alluvial sediments. Satellite photographs, older geologic maps, and recent field observations were used to delineate the boundaries between bedrock and alluvium. About 655 square kilometers, or 36 percent, of the Mexican portion of the river basin is underlain by alluvial fill. In the southern part of the study area, detailed information on thickness and composition of subsurface layers to depths of 500 meters was derived from drill logs. An extensive network of vertical electrical soundings covering much of the central part of the basin allowed for estimates of the location and thickness of clay layers that are confining units within the aquifer system. Across much of the area, the thickness of the silt and confining units was difficult to determine because of problems in distinguishing between these layers and underlying, electrically-conductive Cretaceous siltstone and mudstone. In general, two hydraulically connected sub-basins were identified: one in the southern part of the study area and one in the northern part.

Sedimentary facies and gas accumulation model of Lower Shihezi Formation in Shenguhao area, northern Ordos basin, China

NASA Astrophysics Data System (ADS)

Lin, Weibing; Chen, Lin; Lu, Yongchao; Zhao, Shuai

2017-04-01

The Lower Shihezi formation of lower Permian series in Shenguhao develops the highest gas abundance of upper Paleozoic in China, which has already commercially produced on a large scale. The structural location of Shenguhao belongs to the transition zone of Yimeng uplift and Yishan slope of northern Ordos basin, China. Based on the data of core, well logging and seismic, the sedimentary facies and gas accumulation model have been studied in this paper. Sedimentary facies analysis shows that the braided delta is the major facies type developed in this area during the period of Lower Shihezi formation. The braided delta can be further divided into two microfacies, distributary channel and flood plain. The distributary channel sandbody develops the characteristics of scour surface, trough cross beddings and normal grading sequences. Its seismic reflection structure is with the shape of flat top and concave bottom. Its gamma-ray logging curve is mainly in a box or bell shape. The flood plain is mainly composed of thick mudstones. Its seismic reflection structure is with the shape of parallel or sub-parallel sheet. Its gamma-ray logging curve is mainly in a linear tooth shape. On the whole, the distribution of sandbody is characterized by large thickness, wide area and good continuity. Based on the analysis of the sea level change and the restoration of the ancient landform in the period of Lower Shihezi formation, the sea level relative change and morphology of ancient landform have been considered as the main controlling factors for the development and distribution of sedimentary facies. The topography was with big topographic relief, and the sea level was relatively low in the early stage of Low Shihezi formation. The sandbody distributed chiefly along the landform depressions. The sandbody mainly developed in the pattern of multiple vertical superpositions with thick layer. In the later stage, landform gradually converted to be flat, and strata tended to be gentle. With the sea level gradually increasing, the lateral continuity of sandbody gradually became worse and gradually transformed into the pattern of single and isolated. The analysis of the typical gas accumulation profile of the Lower Shihezi Formation in the study area reveals that the formation of gas pools is mainly controlled by the distribution of sedimentary facies, faults and high point of structures. Generally, the types of gas pool developed in the study area can be divided into up dip pinch out gas pool, fault block gas pool and microstructure gas pool. The coal bearing strata of the underlying Taiyuan Formation and Shanxi Formation are the main hydrocarbon source rocks of the Lower Shihezi Formation. The gas transporting channel and lateral sealing composed by fault and sandbody constitute the key to form an effective gas pool, which usually made up of good lateral sealing, great thickness and good connectivity.

Clay-bearing Fluvial Deposits in Western Ladon Basin, Mars

NASA Astrophysics Data System (ADS)

Weitz, C. M.; Grant, J. A.; Irwin, R. P.; Wilson, S. A.

2013-12-01

More than a dozen outcrops of light-toned layered deposits occur in the uplands to the west of Ladon basin in Margaritifer Terra, Mars. We are evaluating the morphology, mineralogy, and distribution of these sedimentary deposits and associated valley systems that dissect the local Noachian bedrock to understand how they reflect source materials and record environmental and climatic conditions during their emplacement. Several craters, including secondary craters from the Holden impact event, also contain sedimentary deposits, suggesting at least some of the deposits are younger than Mid-to-Late Hesperian. All the deposits appear confined within basins, valleys or craters that are breached by valleys. The deposits typically show numerous beds with variable lithologies, suggesting multiple episodes of deposition and/or changing aqueous conditions over time. CRISM spectra extracted from the deposits typically have absorption features around 1.93 and 2.29 μm, consistent with Fe/Mg-smectites. Several deposits within Arda Valles may have been emplaced when the system was blocked at the eastern end by topography associated with two unnamed craters. Deposition emplaced the clay-bearing layered sediments before an outlet was established, enabling drainage onto the lower-lying floor of Ladon basin and formation of an inverted channel within one of the valleys (Figure 1). All the deposits are located 0.5-2 km above clay-bearing deposits found on the Ladon basin floor, including within Ladon Valles, thereby indicating they were not associated with a lake within the basin or late-stage discharge from Ladon Valles. Instead, their sources appear to be localized and associated with the rim materials of the ancient impact structures or nearby weathered bedrock. The upland deposits may have formed concurrently with deposits found to the south in Eberswalde and Holden craters, indicating precipitation and/or snow melt across much of Margaritifer Terra during the Late Hesperian to Early Amazonian. Figure 1. HiRISE Digital Terrain Model at 5X vertical exaggeration with CRISM spectral parameters overlain in color showing one of the sedimentary deposits in the uplands west of Ladon basin. Clay-bearing deposits appear light-green along the floors of ~150 m deep valleys. Yellow arrows indicate a 15-m high inverted channel within one of the valleys.

Estimation and Simulation of Inter-station Green's Functions in the Beppu-Bay Area, Oita Prefecture, Southwest Japan: the Effect of Sedimentary Basin

NASA Astrophysics Data System (ADS)

Hayashida, T.; Yoshimi, M.; Komatsu, M.; Takenaka, H.

2017-12-01

Continuous long-term observations of ambient noise (microseisms) were performed from August 2014 to February 2017 in the Beppu-Bay area, Oita prefecture, to investigate S-wave velocity structure of deep sedimentary basin (Hayashida et al., 2015SSJ; Yoshimi and Hayashida, 2017WCEE). The observation array consists of 12 broadband stations with an average spacing of 12 km. We applied the seismic interferometry technique to the ambient noise data and derived nine-component ambient noise cross-correlation functions (Z-R, Z-T, Z-Z, R-R, R-T, R-Z, T-R, T-T, and T-Z components) between 66 pairs of stations (distance of 6.4 km to 65.2 km). We assumed the stacked cross-correlation functions as "observed Green's functions" between two stations and estimated group velocities of Rayleigh and Love waves in the frequency between 0.2 and 0.5 Hz (Hayashida et al., 2017AGU-JpGU). Theoretical Green's functions for all stations pairs were also calculated using the finite difference method (HOT-FDM, Nakamura et al., 2012BSSA), with an existing three-dimensional basin structure model (J-SHIS V2) with land and seafloor topography and a seawater layer (Okunaka et al., 2016JpGU) and a newly constructed basin structure model of the target area (Yoshimi et al., 2017AGU). The comparisons between observed and simulated Green's functions generally show good agreements in the frequency range between 0.2 and 0.5 Hz. On the other hand, both observed and simulated Green's functions for some station pairs whose traverse lines run across the deeper part of the sedimentary basin (> 2000 m) show prominent later phases that might be generated and propagated inside the basin. This indicates that the understanding of the phase generation and propagation processes can be a key factor to validate the basin structure model and we investigated the characteristics of the later phases, such as its particle motions and arrival times, using observed and simulated Green's functions in detail. Acknowledgements: This work is supported by the Comprehensive Research on the Beppu-Haneyama Fault Zone funded by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.

Upper-crustal structure beneath the strait of Georgia, Southwest British Columbia

USGS Publications Warehouse

Dash, R.K.; Spence, G.D.; Riedel, M.; Hyndman, R.D.; Brocher, T.M.

2007-01-01

We present a new three-dimensional (3-D) P-wave velocity model for the upper-crustal structure beneath the Strait of Georgia, southwestern British Columbia based on non-linear tomographic inversion of wide-angle seismic refraction data. Our study, part of the Georgia Basin Geohazards Initiative (GBGI) is primarily aimed at mapping the depth of the Cenozoic sedimentary basin and delineating the near-surface crustal faults associated with recent seismic activities (e.g. M = 4.6 in 1997 and M = 5.0 in 1975) in the region. Joint inversion of first-arrival traveltimes from the 1998 Seismic Hazards Investigation in Puget Sound (SHIPS) and the 2002 Georgia Basin experiment provides a high-resolution velocity model of the subsurface to a depth of ???7 km. In the southcentral Georgia Basin, sedimentary rocks of the Cretaceous Nanaimo Group and early Tertiary rocks have seismic velocities between 3.0 and 5.5 km s-1. The basin thickness increases from north to south with a maximum thickness of 7 (??1) km (depth to velocities of 5.5 km s-1) at the southeast end of the strait. The underlying basement rocks, probably representing the Wrangellia terrane, have velocities of 5.5-6.5 km-1 with considerable lateral variation. Our tomographic model reveals that the Strait of Georgia is underlain by a fault-bounded block within the central Georgia Basin. It also shows a correlation between microearthquakes and areas of rapid change in basin thickness. The 1997/1975 earthquakes are located near a northeast-trending hinge line where the thicknesses of sedimentary rocks increase rapidly to the southeast. Given its association with instrumentally recorded, moderate sized earthquakes, we infer that the hinge region is cored by an active fault that we informally name the Gabriola Island fault. A northwest-trending, southwest dipping velocity discontinuity along the eastern side of Vancouver Island correlates spatially with the surface expression of the Outer Island fault. The Outer Island fault as mapped in our seismic tomography model is a thrust fault that projects directly into the Lummi Island fault, suggesting that they are related structures forming a fault system that is continuous for nearly 90 km. Together, these inferred thrust faults may account for at least a portion of the basement uplift at the San Juan Islands. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

Geodynamics and synchronous filling of rift-type basin evolved through compression tectonics

NASA Astrophysics Data System (ADS)

Papdimitriou, Nikolas; Nader, Fadi; Gorini, Christian; Deschamps, Remy

2016-04-01

The Levant Basin falls in the category of frontier basins, and is bounded by the Eratosthenes seamount to the West, the Nile cone delta to the south, Cyprus to the north and Lebanon to the east. The Levant Basin was initially a rift type basin, which is located at a major plate boundary since the Late Triassic. It evolved later on through compression tectonics. The post-rift phase prevailed since the Late Jurassic and is expressed by the gradual initiation of a passive margin. A thick infill, mostly of deep water sediments (about 12 km thick) is accounted for the Levant Basin. The post-rift sediments are pinching-out along the slope of the well preserved (and imaged) eastern margin of the Eratosthenes seamount, which is essentially made up of Mesozoic platform carbonates (about 5 km). Thus, the Eratosthenes carbonate platform was adjacent to the deep marine facies of the Levant Basin until the late Cretaceous/Cenozoic. At that time, both the Eratosthenes seamount and the Levant Basin became part of a foreland basin along the Cyprus Arc zone as a result of the collision of the African and Eurasian plates. The objective of this contribution is to investigate the timing and the mechanisms of flexural subsidence as well as the sedimentary filling of Levant Basin (through a source-to-sink approach) in a well-deformed tectonic region. The interpretation of twenty-four 2D seismic profiles coupled with the available ODP wells, offshore Cyprus, aims to define the primary reflectors and seismic packages. Then, concepts of seismic stratigraphy and sequence stratigraphy are applied to achieve a better understanding of the tectonostratigraphy and sedimentary architecture of the Eratosthenes seamount (as an isolated carbonate platform) and its surroundings. Recent offshore discoveries south of the Eratosthenes seamount (e.g., Zhor) have confirmed the presence of gas accumulations exceeding 30Tcf in subsalt Lower Miocene carbonate buildups, making out the understanding of the evolution of this new frontier hydrocarbon province of great importance.

Stratigraphic and Paleomagnetic Comparisons of Mesoproterozoic Strata and Sills from the Belt Basin, NW Montana, USA, and NW Anabar Shield, Russia: Testing a Precambrian Plate Reconstruction

NASA Astrophysics Data System (ADS)

Sears, J. W.; Pavlov, V.; Veselovskiy, R.; Khudoley, A.

2008-12-01

Mesoproterozoic sedimentary strata and mafic sills overlie Archean and Paleoproterozoic basement rocks with profound unconformity in NW Montana and along the NW margin of the Anabar Shield in northern Siberia. The two localities plot adjacent to one another on a Precambrian plate reconstruction proposed by Sears and Price (2003) that places the NE margin of the Siberian craton against the SW margin of the North American craton. The plate reconstruction predicts that these strata occupied contiguous parts of an intracratonic basin prior to late Neoproterozoic breakup of Rodinia. Here we show that the Mesoproterozoic stratigraphic sequences, sedimentary structures, and lithologies of the NW Anabar margin closely match the Neihart, Chamberlain, and Newland formations of the Little Belt Mountains of Montana. They may predate opening of the Belt Supergroup rift basin at ca. 1500 Ma, when a major mafic magmatic episode occurred in both regions. Preliminary paleomagnetic data from the Siberian section will be compared with the Laurentian APWP to evaluate the reconstruction.

Forearc Basin Stratigraphy and Interactions With Accretionary Wedge Growth According to the Critical Taper Concept

NASA Astrophysics Data System (ADS)

Noda, Atsushi

2018-03-01

Forearc basins are important constituents of sediment traps along subduction zones; the basin stratigraphy records various events that the basin experienced. Although the linkage between basin formation and accretionary wedge growth suggests that mass balance exerts a key control on their evolution, the interaction processes between basin and basement remain poorly understood. This study performed 2-D numerical simulations in which basin stratigraphy was controlled by changes in sediment fluxes with accretionary wedge growth according to the critical taper concept. The resultant stratigraphy depended on the degree of filling (i.e., whether the basin was underfilled or overfilled) and the volume balance between the sediment flux supplied to the basin from the hinterland and the accommodation space in the basin. The trenchward progradation of deposition with onlapping contacts on the trenchside basin floor occurred during the underfilled phase, which formed a wedge-shaped sedimentary unit. In contrast, the landward migration of the depocenter, with the tilting of strata, was characteristic for the overfilled phase. Condensed sections marked stratigraphic boundaries, indicating when sediment supply or accommodation space was limited. The accommodation-limited intervals could have formed during the end of wedge uplift or when the taper angle decreased and possibly associated with the development of submarine canyons as conduits for bypassing sediments from the hinterland. Variations in sediment fluxes and their balance exerted a strong influence on the stratigraphic patterns in forearc basins. Assessing basin stratigraphy could be a key to evaluating how subduction zones evolve through their interactions with changing surface processes.

Thin and layered subcontinental crust of the great Basin western north America inherited from Paleozoic marginal ocean basins?

USGS Publications Warehouse

Churkin, M.; McKee, E.H.

1974-01-01

The seismic profile of the crust of the northern part of the Basin and Range province by its thinness and layering is intermediate between typical continental and oceanic crust and resembles that of marginal ocean basins, especially those with thick sedimentary fill. The geologic history of the Great Basin indicates that it was the site of a succession of marginal ocean basins opening and closing behind volcanic arcs during much of Paleozoic time. A long process of sedimentation and deformation followed throughout the Mesozoic modifying, but possibly not completely transforming the originally oceanic crust to continental crust. In the Cenozoic, after at least 40 m.y. of quiescence and stable conditions, substantial crustal and upper-mantle changes are recorded by elevation of the entire region in isostatic equilibrium, crustal extension resulting in Basin and Range faulting, extensive volcanism, high heat flow and a low-velocity mantle. These phenomena, apparently the result of plate tectonics, are superimposed on the inherited subcontinental crust that developed from an oceanic origin in Paleozoic time and possibly retained some of its thin and layered characteristics. The present anomalous crust in the Great Basin represents an accretion of oceanic geosynclinal material to a Precambrian continental nucleus apparently as an intermediate step in the process of conversion of oceanic crust into a stable continental landmass or craton. ?? 1974.

Challenge for Mesozoic hydrocarbon exploration in the Eastern Indonesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdullah, S.; Rukmiati, M.G.; Sitompul, N.

1996-12-31

The eastern part of Indonesia covers approximately 3 million square kilometers, 35 percent being landmass and 65 percent covered by ocean. Only three of 38 sedimentary basins are producing hydrocarbon (Salawati, Bintuni, and Seram Basins). Oil and gas have discovered in the Lariang, Bone, Timor, Banggai, Sula and Biak Basins, however the discoveries have not developed yet. Hydrocarbon systems in Northern Australia and Papua New Guinea give the major contributions to the geological idea of Pre-Tertiary section in the less explored area in the Eastern Indonesia. The Triassic-Middle Jurassic marine carbonaceous shale sequences are the main hydrocarbon source rock inmore » the Irian Jaya and surrounding area (Buton, gula and Seram basins). The main Mesozoic reservoir are the Kembelangan Formation in the Bintuni Basin of Irian Jaya and Bobong Formation in the North Sula Region. Exploration play types in the Eastern Indonesia can be divided into five types: 1 - Peri Cratonic, 2 - Marginal Rift Graben, 3 - Thrust Fold Belt Island Arc, 4 - Early Collision and 5 -Microcontinental Block - Advanced Collision. Recent discoveries through Mesozoic section in Eastern Indonesia are: Roabiba-1 (1990) in Bintuni Basin-Irian Jaya (Kambelangan Formation); Loku- 1 (1990) in North Sula region (Pre-Tertiary sediments); Oseil-1 (1993/94) in Bula-Seram Basin (Jurassic Manusela Formation); Elang-1 (1 994); Kakaktua-1 (1994) and Laminaria-1 in North Bonaparte Basin (Upper Jurassic Sands).« less

Monitoring of Land Deformation Due to Oil Production by InSAR Time Series Analysis Using PALSAR Data in Bolivarian Republic of Venezuela

NASA Astrophysics Data System (ADS)

Deguchi, Tomonori; Narita, Tatsuhiko

2015-05-01

The target area of this study is the Maracaibo sedimentary basin located in the western part of Bolivarian Republic of Venezuela. The full-scale exploration and development for oil resources in Venezuela which was the greatest oil-producing country in South America had begun at the Maracaibo sedimentary basin in the 1910s, and it was a center of the oil product in Venezuela until the 1980s. But, in most of oil fields in the Maracaibo sedimentary basin, there is concern over the drain on recoverable reserves due to deterioration, and the production amount of petroleum in Venezuela has been diminishing these days. Leveling and GPS surveying were carried out in the past, and they revealed that the large-scale subsidence phenomenon of which cumulative subsidence amount was approximately 5 meter had occurred. The authors applied the vertical displacement measurement by InSAR time series analysis using PALSAR data obtained in the Fine-beam and ScanSAR observation mode. As a result, it could be confirmed clear ground deformation in the surrounding of three oil fields (Tia Juana, Lagunillas and Bachaquero) and easily recognized that the areas of phase anomalies detected by this analysis had expanded and the number of interference fringes had increased over time. The annual velocity of vertical ground surface displacement measured by InSAR time series analysis was -51 mm per year, -103 mm per year and -58 mm per year in Tia Juana, Lagunillas and Bachaquero oil field respectively. The tendency that an earth surface shifted towards the center of phase anomalies was detected from the result of the horizontal ground change measurement. It was interpreted from Google Earth and Landsat images that oil-related facilities (mainly bowling stations) were built intensively over the areas where phase anomalies were detected. Therefore, it was inferred that there was a high association between the operation activity of the oil field and ground deformation. In addition, the deterioration is remarkable in the oil fields of the Maracaibo basin and oil production volume has been declining, on the other hand the spatial volume of the ground surface deformation also showed a clear decreasing trend.

Neogene stratigraphy and Andean geodynamics of southern Ecuador

NASA Astrophysics Data System (ADS)

Hungerbühler, Dominik; Steinmann, Michael; Winkler, Wilfried; Seward, Diane; Egüez, Arturo; Peterson, Dawn E.; Helg, Urs; Hammer, Cliff

2002-01-01

The present paper reviews Tertiary volcanic and sedimentary formations in the Inter-Andean region of southern Ecuador (between 2°S and 4°20'S) in order to develop a geodynamic model of the region. The formations occur in the southern shallow prolongation of the Inter-Andean Valley between the Cordillera Real to the east, and the Cordillera Occidental and Amotape-Tahuín Provinces to the west. One hundred fifty zircon fission-track analyses has established a detailed chronostratigraphy for the sedimentary and volcanic formations and several small intrusions. The Paleogene to early Miocene formations are dominated by intermediate and acidic volcanic and pyroclastic rocks. In addition, relics of Eocene continental sedimentary series have been identified. The Neogene sedimentary series lie unconformably on deformed and eroded metamorphic, sedimentary and volcanic formations. They were deposited in two stages, which are separated by a major unconformity dated at ≈10-9 Ma. (1) During the middle and early late Miocene (≈15-10 Ma) marginal marine deltaic, lagoonal, lacustrine and fluvial environments prevailed, which we group under the heading "Pacific Coastal sequences". They presumably covered a greater surface area in southern Ecuador than their present occurrence in small topographic depressions. We suggest that they were deposited in the shallow marine Cuenca and Loja Embayments. Deposition in a marginal marine environment is also supported by the occurrence of brackish water ostracods and other fauna. (2) Above the regional (angular) unconformity, the coastal facies are overlain by late Miocene (≈9-5 Ma) continental alluvial fan and fluvial facies which are in turn covered by mainly airborne volcanic material. They represent the "Intermontane sequences" of the basins of Cuenca, Girón-Santa Isabel, Nabón, Loja and Malacatos-Vilcabamba. Sedimentologic and stratigraphic results are used to discuss the tectonic setting of Neogene sedimentation in the forearc and arc domain of the Ecuadorian subduction system. During the Pacific Coastal stage, northward displacement of the coastal forearc block along the Calacali-Pallatanga fault zone has driven crustal collapse in the Inter-Andean region. As a result, extensional subsidence drove the eastward ingression of shallow seas into the Cuenca and Loja Embayments from the Manabí and Progreso Basins to the west. Tectonic inversion in the forearc area during the early late Miocene (at ≈9.5 Ma) reflects the initiation of W-E oriented compression and uplift in the Inter-Andean region and the establishment of smaller Intermontane stage basins, which host the continental sequences. Coeval topographic rise of the Cordillera Occidental is indicated by the onset of clastic input from the west. The small Intermontane Basin of Nabón (≈8.5-7.9 Ma) formed during the period of maximum compression. The present data prove that the Neogene Andean forearc and arc area in southern Ecuador was a site of important but variable tectonic activity, which was presumably driven by the collision and coupling of the Carnegie Ridge with the Ecuadorian margin since ≈15-9 Ma.

Restoration of original 3D sedimentary geometries in deformed basin fill supporting reservoir characterization

NASA Astrophysics Data System (ADS)

Back, S.

2009-04-01

A large progradational clastic system centred on Brunei Darussalam has been present on the NW Borneo margin since the early middle Miocene. This system has many sedimentary and structural similarities with major deltaic provinces such as the Niger and Nile. It differs from these systems by being affected in the hinterland by contemporaneous compressional tectonics. Uplift partially forced strong progradation of the clastic system, but also folded older deltaic units. Erosion and the exhumation of folded strata in the area of the Jerudong Anticline resulted in the exposure of large-scale prograding clinoforms and syn-sedimentary deltaic faults of middle Miocene age along a natural cross-section of several tens of kilometres in extent. Westward of the key outcrop sites on the Jerudong Anticline, the middle Miocene deltaic units are overlain by late Miocene, Pliocene and Quaternary clastics up to 3 kilometres thick. Both, the middle Miocene target units of this study as well as the late Miocene to recent overburden are recorded in the subsurface of the Belait Syncline on regional 2D seismic lines (total line length around 1400 km) and at 7 well locations. In this study, we integrate the available geophysical subsurface information with existing structural, sedimentological and geomorphological field data of the "classic" Jerudong Anticline exposures (e.g., Back et al. 2001, Morley et al. 2003, Back et al. 2005) into a static 3D surface-subsurface model that provides quantitative constraints on the structural and stratigraphic architecture of the Miocene Belait delta and the overlying units in three dimensions, supporting basin-scale as well as reservoir-scale analysis of the subsurface rock volume. Additionally, we use the static surface-subsurface model as input for a tectonic retro-deformation of the study area, in which the 3D paleo-relief of the middle Miocene Belait delta is restored by unfolding and fault balancing (Back et al. 2008). This kinematic reconstruction ultimately provides a detailed view into the stratal architecture of middle Miocene delta clinoforms, indicating a close relationship between delta-lobe activity, clinoform morphology, and the generation of slumps and turbidites. Literature BACK, S., MORLEY, C.K., SIMMONS, M.D. & LAMBIASE, J.J. (2001): Depositional environment and sequence stratigraphy of Miocene deltaic cycles exposed along the Jerudong anticline, Brunei Darussalam. - Journal of Sedimentary Research, 71: 915-923. BACK, S., TIOE HAK JING, TRAN XUAN THANG & MORLEY, C.K. (2005): Stratigraphic development of synkinematic deposits in a large growth-fault system, onshore Brunei Darussalam. - Journal of the Geological Society, London, 162: 243-258. BACK, S., STROZYK, F., KUKLA, P.A. & LAMBIASE, J.J. (2008): 3D restoration of original sedimentary geometries in deformed basin fill, onshore Brunei Darussalam, NW Borneo. Basin Research, 20: 99-117. MORLEY, C.K., BACK, S., VANRENSBERGEN, P., CREVELLO, P. & LAMBIASE, J.J. (2003): Characteristics of repeated, detached, Miocene -Pliocene tectonic inversion events, in a large delta province on an active margin, Brunei Darussalam, Borneo. - Journal of Structural Geology, 25: 1147-1169.

Geologic summary of the Appalachian Basin, with reference to the subsurface disposal of radioactive waste solutions

USGS Publications Warehouse

Colton, G.W.

1962-01-01

The Appalachian basin is an elongate depression in the crystalline basement complex< which contains a great volume of predominantly sedimentary stratified rocks. As defined in this paper it extends from the Adirondack Mountains in New York to central Alabama. From east to west it extends from the west flank of the Blue Ridge Mountains to the crest of the Findlay and Cincinnati arches and the Nashville dome. It encompasses an area of about 207,000 square miles, including all of West Virginia and parts of New York, New Jersey, Pennsylvania, Ohio, Maryland, Virginia, Kentucky, Tennessee, North Carolina, Georgia, and Alabama. The stratified rocks that occupy the basin constitute a wedge-shaped mass whose axis of greatest thickness lies close to and parallel to the east edge of the basin. The maximum thickness of stratified rocks preserved in any one part of the basin today is between 35,000 and 40,000 feet. The volume of the sedimentary rocks is approximately 510,000 cubic miles and of volcanic rocks is a few thousand cubic miles. The sedimentary rocks are predominantly Paleozoic in age, whereas the volcanic rocks are predominantly Late Precambrian. On the basis of gross lithology the stratified rocks overlying the crystalline basement complex can be divided into nine vertically sequential units, which are designated 'sequences' in this report. The boundaries between contiguous sequences do not necessarily coincide with the commonly recognized boundaries between systems or series. All sequences are grossly wedge shaped, being thickest along the eastern margin of the basin and thinnest along the western margin. The lowermost unit--the Late Precambrian stratified sequence--is present only along part of the eastern margin of the basin, where it lies unconformably on the basement complex. It consists largely of volcanic tuffs and flows but contains some interbedded sedimentary rocks. The Late Precambrian sequence is overlain by the Early Cambrian clastic sequence. Where the older sequence is absent, the Early Cambrian sequence rests on the basement complex. Interbedded fine- to coarse-grained noncarbonate detrital rocks comprise the bulk of the sequence, but some volcanic and carbonate rocks are included. Next above is the Cambrian-Ordovician carbonate sequence which consists largely of limestone and dolomite. Some quartzose sandstone is present in the lower part in the western half of the basin, and much shale is present in the upper part in the southeast part of the basin. The next higher sequence is the Late Ordovician clastic sequence, which consists largely of shale, siltstone, and sandstone. Coarse-grained light-gray to red rocks are common in the sequence along the eastern side of the basin, whereas fine-grained dark-gray to black calcareous rocks are common along the west side. The Late Ordovician clastic sequence is overlain--unconformably in many places--by the Early Silurian clastic sequence. The latter comprises a relatively thin wedge of coarse-grained clastic rocks. Some of the most prolific oil- and gas-producing sandstones in the Appalachian basin are included. Among these are the 'Clinton' sands of Ohio, the Medina Sandstones of New York and Pennsylvania, and the Keefer or 'Big Six' Sandstone of West Virginia and Kentucky. Conformably overlying the Early Silurian clastic sequence is the Silurian-Devonian carbonate sequence, which consists predominantly of limestone and dolomite. It also contains a salt-bearing unit in the north-central part of the basin and a thick wedge of coarse-grained red beds in the northeastern part. The sequence is absent in much of the southern part of the basin. Large volumes of gas and much oil are obtained from some of its rocks, especially from the Oriskany Sandstone and the Huntersville Chert. The Silurian-Devonian carbonate sequence is abruptly overlain by the Devonian clastic sequence--a thick succession of interbedded shale, mudrock, siltstone, and sandstone. Colors range f

Influence of bedrock geology on water chemistry of slope wetlands and headwater streams in the southern Rocky Mountains

Treesearch

Monique LaPerriere Nelson; Charles C. Rhoades; Kathleen A. Dwire

2011-01-01

We characterized the water chemistry of nine slope wetlands and adjacent headwater streams in Colorado subalpine forests and compared sites in basins formed on crystalline bedrock with those formed in basins with a mixture of crystalline and sedimentary bedrock. The pH, Ca2+, Mg2+, NH4 +, acid neutralizing capacity, and electrical conductivity of wetland porewater and...

Cordilleran Intermontane thermotectonic history and implications for neotectonic structure and petroleum systems, British Columbia, Canada

NASA Astrophysics Data System (ADS)

Majorowicz, Jacek; Osadetz, Kirk

2008-04-01

Heat flow increases northward along Intermontane Belt in the western Canadian Cordillera, as shown by geothermal differences between Bowser and Nechako sedimentary basins, where geothermal gradients and heat flows are ˜30 mK/m and ˜90 mW/m2 compared to ˜32 mK/m and 70 -80 mW/m2, respectively. Sparse temperature profile data from these two sedimenatary basins are consistent with an isostatic model of elevation and crustal parameters, which indicate that Bowser basin heat flow should be ˜20 mW/m2 greater than Nechako basin heat flow. Paleothermometric indicators record a significant northward increasing Eocene or older erosional denudation, up to ˜7 km. None of the heat generation, tectonic reorganization at the plate margin, or erosional denudation produce thermal effects of the type or magnitude that explain the north-south heat flow differences between Nechako and Bowser basins. The more southerly Nechako basin, where heat flow is lower, has lower mean elevation, is less deeply eroded, and lies opposite the active plate margin. In contrast, Bowser basin, where heat flow is higher, has higher mean elevation, is more deeply eroded, and sits opposite a transform margin that succeeded the active margin ˜40 Ma. Differences between Bowser and Nechako basins contrast with the tectonic history and erosion impacts on thermal state. Tectonic history and eroded sedimentary thickness suggest that Bowser basin lithosphere is cooling and contracting relative to Nechako basin lithosphere. This effect has reduced Bowser basin heat flow by ˜10-20 mW/m2 since ˜40 Ma. Neither can heat generation differences explain the northerly increasing Intermontane Belt heat flow. A lack of extensional structures in the Bowser basin precludes basin and range-like extension. Therefore, another, yet an unspecified mechanism perhaps associated with the Northern Cordilleran Volcanic Province, contributes additional heat. Bowser basin’s paleogeothermal gradients were higher, ˜36 mK/m, before the Eocene and this might affect petroleum and metallogenic systems.

Pore Water Chemistry as Sensitive Indicators for Fluid Flow in Brazos-Trinity Basin #4 and Ursa Basin, Northeast Gulf of Mexico (IODP Expedition 308)

NASA Astrophysics Data System (ADS)

Jiang, S.; Gilhooly, W.; Takano, Y.; Flemings, P.; Behrmann, J.; John, C.

2005-12-01

Rapid sediment loading drives overpressure in marine sedimentary basins around the world. During IODP Expedition 308, two basins (Brazos-Trinity Basin #4 and Ursa Basin) with large different sedimentary loading of turbidite and hemipelagic sediments in the northeast Gulf of Mexico, were investigated to characterize in-situ spatial variations in temperature, pressure, and rock and fluid physical properties and chemistry. Pore water chemical compositions including alkalinity, salinity, pH, anions (Cl, SO4, PO4, H4SiO4), cations (Na, K, Ca, Mg), trace metals (Li, B, Sr, Ba, Fe, Mn), were analyzed in four drill holes at sites U1319, U1320, U1322, and U1324, in the Brazos-Trinity Basin #4 and Ursa Basin. At all sites, pore water chemistry shows great variability at shallow depths with maximam or miminum values corresponding well to seismic reflectors and lithostratigraphic units. The sulfate profile shows a dramatic decrease in SO4 content with a sulfate-methane interface (SMI) of 15 mbsf at Site 1319 and 22 mbsf at Site 1320 in the Brazos-Trinity Basin #4 Basin. In contrast, the sulfate- methane interfaces (SMI) are much deeper in Ursa Basin, i.e., 74 mbsf at Site 1322, and 94 mbsf at Site 2324. The deep SMI in Ursa Basin suggest relatively slow anaerobic degradation of organic matter considering the location of drilling site though we do not determine sulfate reducing rate with organic matter or methane as substrate at this leg. The downhole consumption of sulfate coincides with a concomitant increase in alkalinity and a decrease of Mn, Ca, Mg, Sr, and Li. Furthermore, initial pore water chemistry results appear to be influence by hydrogeologic fluid flow in both basins. Coincidence between pore water profile concentration maxima and parallel seismic reflectors may suggest that these seismic surfaces occur along specific stratigraphic units, which serve as channels for lateral fluid flow. Overall, the downhole variations in interstitial water chemistry may reflect a combination of processes, including anaerobic degradation of organic matter, diagenetic carbonate precipitation/dissolution, and fluid flow pathways.

3D gravity inversion and uncertainty assessment of basement relief via Particle Swarm Optimization

NASA Astrophysics Data System (ADS)

Pallero, J. L. G.; Fernández-Martínez, J. L.; Bonvalot, S.; Fudym, O.

2017-04-01

Nonlinear gravity inversion in sedimentary basins is a classical problem in applied geophysics. Although a 2D approximation is widely used, 3D models have been also proposed to better take into account the basin geometry. A common nonlinear approach to this 3D problem consists in modeling the basin as a set of right rectangular prisms with prescribed density contrast, whose depths are the unknowns. Then, the problem is iteratively solved via local optimization techniques from an initial model computed using some simplifications or being estimated using prior geophysical models. Nevertheless, this kind of approach is highly dependent on the prior information that is used, and lacks from a correct solution appraisal (nonlinear uncertainty analysis). In this paper, we use the family of global Particle Swarm Optimization (PSO) optimizers for the 3D gravity inversion and model appraisal of the solution that is adopted for basement relief estimation in sedimentary basins. Synthetic and real cases are illustrated, showing that robust results are obtained. Therefore, PSO seems to be a very good alternative for 3D gravity inversion and uncertainty assessment of basement relief when used in a sampling while optimizing approach. That way important geological questions can be answered probabilistically in order to perform risk assessment in the decisions that are made.

The Bowland Basin, NW England: Base metal mineralisation and its relationship to basin evolution

NASA Astrophysics Data System (ADS)

Gaunt, Jonathan Mark

The Bowland Basin of NW England is a Carboniferous half graben. The Basin was initiated in the Devonian and actively extended during the Carboniferous until the late Westphalian. From the late Westphalian to the early Permian the Bowland Basin underwent inversion in response to Hercynian collision tectonics. Renewed subsidence commenced in the Permian and continued until inversion in the Cenozoic. The sedimentary succession of the Bowland Basin is dominated by Carboniferous strata, but some Permo-Triassic strata are present. The basal sedimentary succession may be comprised of Devonian to early Dinantian syn-rift clastics. The main Dinantian succession is comprised of interbedded limestones, calcareous mudstones and clastic strata. The Dinantian strata include the Waulsortian-facies Clitheroe Limestone and the Limekiln Wood Limestone, both of which host mineralisation. The overlying Namurian is comprised of shales and sandstones. The diagenetic history of the Limekiln Wood Limestone and Waulsortian-facies Clitheroe Limestone in the Cow Ark-Marl Hill Moor district is a function of changes in the burial environment during the Carboniferous. Both exhibit a pre-basin inversion diagenetic sequence that changes with time from shallow to moderate burial depth cements. Late Carbonifeous basin inversion resulted in the formation of tectonic stylolites. Tectonic stylolitisation was postdated by dolomitisation and silicification. Dolomitisation and silicification are suggested to have taken place in the deep burial environment. The base metal mineralisation studied in this work comes from the Cow Ark- Marl Hill Moor district, which is sited on the present basin inversion axis. Mineralisation occurs as four distinct episodes (Period 1, Period 2, Period 3 and Post-Period 3) within a complex multigeneration vein suite. The vein suite, which postdates tectonic stylolitisation and hence end-Carboniferous basin inversion, is comprised of calcite, baroque dolomite, baroque ankerite and siderite. The veins, which are often spatially associated with faults, exhibit a variety of morphologies, and are largely hosted by hydraulic shear fractures. Compositional variations between the different vein carbonates occur with time and the calcites, baroque dolomites, baroque ankerites and siderites are interpreted to have had several different fluid sources. Fluids precipitating siderite, baroque dolomite and baroque ankerite may have been produced by clay mineral transformations and decarboxylation of organic matter within the calcareous strata. The multiple vein calcite generations belong to three MnO:FeO compositional classes, each occupying a specific paragenetic position. The trend from ferroan to manganoan calcite with time may be a consequence of calcite-forming fluids being derived from successively shallower depths within the sedimentary succession, or of increased permeation by meteoric fluids. (Abstract shortened by ProQuest.).

Oil shale and nahcolite resources of the Piceance Basin, Colorado

USGS Publications Warehouse

,

2010-01-01

This report presents an in-place assessment of the oil shale and nahcolite resources of the Green River Formation in the Piceance Basin of western Colorado. The Piceance Basin is one of three large structural and sedimentary basins that contain vast amounts of oil shale resources in the Green River Formation of Eocene age. The other two basins, the Uinta Basin of eastern Utah and westernmost Colorado, and the Greater Green River Basin of southwest Wyoming, northwestern Colorado, and northeastern Utah also contain large resources of oil shale in the Green River Formation, and these two basins will be assessed separately. Estimated in-place oil is about 1.5 trillion barrels, based on Fischer a ssay results from boreholes drilled to evaluate oil shale, making it the largest oil shale deposit in the world. The estimated in-place nahcolite resource is about 43.3 billion short tons.

Angola seismicity

NASA Astrophysics Data System (ADS)

Neto, Francisco António Pereira; França, George Sand; Condori, Cristobal; Sant'Anna Marotta, Giuliano; Chimpliganond, Cristiano Naibert

2018-05-01

This work describes the development of the Angolan earthquake catalog and seismicity distribution in the Southwestern African Plate, in Angola. This region is one of the least seismically active, even for stable continental regions (SCRs) in the world. The maximum known earthquake had a magnitude of 6.0 Ms, while events with magnitudes of 4.5 have return period of about 10 years. Events with magnitude 5 and above occur with return period of about 20 years. Five seismic zones can be confirmed in Angola, within and along craton edges and in the sedimentary basins including offshore. Overall, the exposed cratonic regions tend to have more earthquakes compared to other regions such as sedimentary basins. Earthquakes tend to occur in Archaic rocks, especially inside preexisting weakness zones and in tectonic-magmatic reactivation zones of Mesozoic and Meso-Cenozoic, associated with the installation of a wide variety of intrusive rocks, strongly marked by intense tectonism. This fact can be explained by the models of preexisting weakness zones and stress concentration near intersecting structures. The Angolan passive margin is also a new region where seismic activity occurs. Although clear differences are found between different areas along the passive margin, in the middle near Porto Amboim city, seismic activity is more frequent compared with northwestern and southwestern regions.

A regional view of urban sedimentary basins in Northern California based on oil industry compressional-wave velocity and density logs

USGS Publications Warehouse

Brocher, T.M.

2005-01-01

Compressional-wave (sonic) and density logs from 119 oil test wells provide knowledge of the physical properties and impedance contrasts within urban sedimentary basins in northern California, which is needed to better understand basin amplification. These wire-line logs provide estimates of sonic velocities and densities for primarily Upper Cretaceous to Pliocene clastic rocks between 0.1 - and 5.6-km depth to an average depth of 1.8 km. Regional differences in the sonic velocities and densities in these basins largely 1reflect variations in the lithology, depth of burial, porosity, and grain size of the strata, but not necessarily formation age. For example, Miocene basin filling strata west of the Calaveras Fault exhibit higher sonic velocities and densities than older but finer-grained and/or higher-porosity rocks of the Upper Cretaceous Great Valley Sequence. As another example, hard Eocene sandstones west of the San Andreas Fault have much higher impedances than Eocene strata, mainly higher-porosity sandstones and shales, located to the east of this fault, and approach those expected for Franciscan Complex basement rocks. Basement penetrations define large impedence contrasts at the sediment/basement contact along the margins of several basins, where Quaternary, Pliocene, and even Miocene deposits directly overlie Franciscan or Salinian basement rocks at depths as much as 1.7 km. In contrast, in the deepest, geographic centers of the basins, such logs exhibit only a modest impedance contrast at the sediment/basement contact at depths exceeding 2 km. Prominent (up to 1 km/sec) and thick (up to several hundred meters) velocity and density reversals in the logs refute the common assumption that velocities and densities increase monotonically with depth.

Miocene climate variations in the Moesian Platform sediments based on sedimentology and biomarkers

NASA Astrophysics Data System (ADS)

Butiseaca, Geanina; Vasiliev, Iuliana; Rabagia, Traian; Dinu, Corneliu; Mulch, Andreas

2017-04-01

During the Miocene the Moesian Platform (southern Romania and northern Bulgaria) had a complicated flexural behavior due to the mobility of the nearby orogens. The different behavior induced varying sediment charges, sediment distribution and sediment types. The northern part of the study area (on which the Dacian Basin is overlaid) is characterized by siliciclastic units with dominantly deep facieses, while the southern part is characterized by carbonate production in shallower basin waters. Since the Miocene, the Dacian and Black Sea basins have been highly sensitive to fluctuations in the hydrological cycle. To establish the dynamic evolution of the basin and the climate variations during the Miocene, we have sampled both northern and southern margins of the basin. To discriminate between the tectonic imprint and the eustatic influence over the sedimentation rate we have chosen a multidisciplinary approach including sedimentology, tectonics and organic geochemistry based reconstructions. The sedimentary succession is interrupted by few unconformities correspondent with the main phases of orogeny (in the Carpathian Foredeep) while the southern part seems to have been exposed more often expressed in the geological record by a higher number of unconformities and paleo-soils levels. The n-alkanes distribution recovered from the lipids extracted from the sedimentary rocks indicates a mixture of terrestrial and marine input in the northern, Romanian, closer to Carpathians, part of the Dacian Basin. Surprisingly, the southern, Bulgarian side, showed a more predominant terrestrial input (with higher contribution of the long chain n-alkanes) at least for the Sarmatian (arround 10 Ma). The estimated paleotemperatures based on branched GDGT's indicate much warmer conditions than present day, up to a value of 20 C mean annual temperatures. We will further investigate the paleoenvironmental changes during the latest Miocene of the Dacian basin, using the biomarker approach on the organic biomarkers.

Report on workshop to incorporate basin response in the design of tall buildings in the Puget Sound region, Washington

USGS Publications Warehouse

Chang, Susan; Frankel, Arthur D.; Weaver, Craig S.

2014-01-01

On March 4, 2013, the City of Seattle and the U.S. Geological Survey (USGS) convened a workshop of 25 engineers and seismologists to provide recommendations to the City for the incorporation of amplification of earthquake ground shaking by the Seattle sedimentary basin in the design of tall buildings in Seattle. The workshop was initiated and organized by Susan Chang, a geotechnical engineer with the City of Seattle Department of Planning and Development, along with Art Frankel and Craig Weaver of the USGS. C.B. Crouse of URS Corporation, Seattle made key suggestions for the agenda. The USGS provided travel support for most of the out-of-town participants. The agenda and invited attendees are given in the appendix. The attendees included geotechnical and structural engineers working in Seattle, engineers with experience utilizing basin response factors in other regions, and seismologists who have studied basin response in a variety of locations. In this report, we summarize the technical presentations and the recommendations from the workshop.

The organic geochemistry of black sedimentary barite: significance and implications of trapped fatty acids

USGS Publications Warehouse

Miller, R.E.; Brobst, D.A.; Beck, P.C.

1977-01-01

Fatty acids isolated in sedimentary black barite (BaSO4) from Arkansas and Nevada were identified by gas chromatography-mass spectroscopy. The dominant or major fatty acids found in these beds of barite are C16:0, C18:0, and C18:1. The occurrence and distribution of these acids in this type of rock may serve as "molecular fingerprints" of microbial biogeochemical processes. The organic matter and associated microorganisms are shown to be trapped within the finely crystalline barite, thus forming a closed system for microbial diagenesis. Important differences that occur in the distribution of the lesser or minor fatty acids probably result from: (1) the nature of the progenitor organic detritus in the environment of barite deposition: and (2) the subsequent degree of microbiological alteration of the parent organic debris swept into and trapped in the depositional environment. Three general models of sedimentary environments are proposed in which anoxic conditions may prevail and where barium sulfate (BaSO4) may precipitate: (1) in a silled basin with semi-restricted circulation; (2) on an outer continental shelf where the slope is encroached upon by water of the oxygen minimum layer; (3) on a low-energy, inner shelf or semi-restricted embayment impinged by a wedge of anoxic water. The major geochemical and geological parameters which are believed to be the significant factors controlling the formation and high grade of these organic-rich, black bedded barites are: (1) a unique source of barium-rich fluid that only contains trace amounts of other elements; (2) the presence of an anoxic bottom environment within the depositional basin; (3) a reflux source of sulfate ion; (4) an adequate source of organic matter. The results of this study may serve as guidelines for future exploration in similar, untested sedimentary basins, especially those with rocks of middle Paleozoic age. ?? 1977.

3D depth-to-basement and density contrast estimates using gravity and borehole data

NASA Astrophysics Data System (ADS)

Barbosa, V. C.; Martins, C. M.; Silva, J. B.

2009-05-01

We present a gravity inversion method for simultaneously estimating the 3D basement relief of a sedimentary basin and the parameters defining the parabolic decay of the density contrast with depth in a sedimentary pack assuming the prior knowledge about the basement depth at a few points. The sedimentary pack is approximated by a grid of 3D vertical prisms juxtaposed in both horizontal directions, x and y, of a right-handed coordinate system. The prisms' thicknesses represent the depths to the basement and are the parameters to be estimated from the gravity data. To produce stable depth-to-basement estimates we impose smoothness on the basement depths through minimization of the spatial derivatives of the parameters in the x and y directions. To estimate the parameters defining the parabolic decay of the density contrast with depth we mapped a functional containing prior information about the basement depths at a few points. We apply our method to synthetic data from a simulated complex 3D basement relief with two sedimentary sections having distinct parabolic laws describing the density contrast variation with depth. Our method retrieves the true parameters of the parabolic law of density contrast decay with depth and produces good estimates of the basement relief if the number and the distribution of boreholes are sufficient. We also applied our method to real gravity data from the onshore and part of the shallow offshore Almada Basin, on Brazil's northeastern coast. The estimated 3D Almada's basement shows geologic structures that cannot be easily inferred just from the inspection of the gravity anomaly. The estimated Almada relief presents steep borders evidencing the presence of gravity faults. Also, we note the existence of three terraces separating two local subbasins. These geologic features are consistent with Almada's geodynamic origin (the Mesozoic breakup of Gondwana and the opening of the South Atlantic Ocean) and they are important in understanding the basin evolution and in detecting structural oil traps.

Mapping Neogene and Quaternary sedimentary deposits in northeastern Brazil by integrating geophysics, remote sensing and geological field data

NASA Astrophysics Data System (ADS)

Andrades-Filho, Clódis de Oliveira; Rossetti, Dilce de Fátima; Bezerra, Francisco Hilario Rego; Medeiros, Walter Eugênio; Valeriano, Márcio de Morisson; Cremon, Édipo Henrique; Oliveira, Roberto Gusmão de

2014-12-01

Neogene and late Quaternary sedimentary deposits corresponding respectively to the Barreiras Formation and Post-Barreiras Sediments are abundant along the Brazilian coast. Such deposits are valuable for reconstructing sea level fluctuations and recording tectonic reactivation along the passive margin of South America. Despite this relevance, much effort remains to be invested in discriminating these units in their various areas of occurrence. The main objective of this work is to develop and test a new methodology for semi-automated mapping of Neogene and late Quaternary sedimentary deposits in northeastern Brazil integrating geophysical and remote sensing data. The central onshore Paraíba Basin was selected due to the recent availability of a detailed map based on the integration of surface and subsurface geological data. We used airborne gamma-ray spectrometry (i.e., potassium-K and thorium-Th concentration) and morphometric data (i.e., relief-dissection, slope and elevation) extracted from the digital elevation model (DEM) generated by the Shuttle Radar Topography Mission (SRTM). The procedures included: (a) data integration using geographic information systems (GIS); (b) exploratory statistical analyses, including the definition of parameters and thresholds for class discrimination for a set of sample plots; and (c) development and application of a decision-tree classification. Data validation was based on: (i) statistical analysis of geochemical and airborne gamma-ray spectrometry data consisting of K and Th concentrations; and (ii) map validation with the support of a confusion matrix, overall accuracy, as well as quantity disagreement and allocation disagreement for accuracy assessment based on field points. The concentration of K successfully separated the sedimentary units of the basin from Precambrian basement rocks. The relief-dissection morphometric variable allowed the discrimination between the Barreiras Formation and the Post-Barreiras Sediments. In addition, two units of the latter (i.e., PB1 and PB2) previously mapped in the field were promptly separated based on Th concentration. A regression analysis indicated that the relationship between geophysical and geochemical values obtained for the PB1, PB2 and Barreiras Formation is significant (R-squared = 0.91; p-value <0.05). Map validation presented a high overall accuracy of 84%, with a coefficient of quantity disagreement of 12% and a coefficient of allocation disagreement of 8%. These results indicate that the methodology applied in the central onshore Paraíba Basin can be successfully used for mapping the Barreiras Formation and Post-Barreiras Sediments in other areas of the Brazilian coast. The ability to rapidly and precisely map these units using such methodology could reveal their geographic distribution along the northeastern coast of Brazil.

Structure, stratigraphy and petroleum geology of the south east Nam Con Son Basin, offshore Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fraser, A.J.; Matthews, S.J.; Lowe, S.

1996-12-31

Recent exploration of the south east Nam Con Son Basin, offshore Vietnam, by BP in alliance with Statoil has involved acquisition of new seismic and well data. These new data have allowed re-evaluation of the tectono-stratigraphic development and petroleum geology, and have provided additional constraints on the regional tectonic evolution. The offshore Vietnamese basins have evolved in response to the complex relative motions of Indochina, Peninsular Malaysia, Borneo and the South China Sea during the Cenozoic. On the regional scale these motions have been accommodated by strike-slip fault development, rifting and contraction. In the Nam Con Son Basin these motionsmore » have interacted in different ways from the Palaeogene to recent. Two rifting episodes are recognized; a Palaeogene phase dominated by E-W trending extensional faults, and a Miocene phase dominated by N-S to NE-SW trending faults. The structural evolution is complicated by a pulse of mild contraction during the Middle Miocene. The sedimentary fill of the basin evolves from continental fluvio-lacustrine in the Palaeogene through to fully marine following the second phase of rifting in the Miocene. This pulsed structural and stratigraphic evolution has resulted in basinwide deposition of source, reservoir and seal facies, and produced a variety of potential trapping styles. This paper describes the hydrocarbon habitat of the south east Nam Con Son Basin within the context of the regional tectono-stratigraphic model.« less

Structure, stratigraphy and petroleum geology of the south east Nam Con Son Basin, offshore Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fraser, A.J.; Matthews, S.J.; Lowe, S.

1996-01-01

Recent exploration of the south east Nam Con Son Basin, offshore Vietnam, by BP in alliance with Statoil has involved acquisition of new seismic and well data. These new data have allowed re-evaluation of the tectono-stratigraphic development and petroleum geology, and have provided additional constraints on the regional tectonic evolution. The offshore Vietnamese basins have evolved in response to the complex relative motions of Indochina, Peninsular Malaysia, Borneo and the South China Sea during the Cenozoic. On the regional scale these motions have been accommodated by strike-slip fault development, rifting and contraction. In the Nam Con Son Basin these motionsmore » have interacted in different ways from the Palaeogene to recent. Two rifting episodes are recognized; a Palaeogene phase dominated by E-W trending extensional faults, and a Miocene phase dominated by N-S to NE-SW trending faults. The structural evolution is complicated by a pulse of mild contraction during the Middle Miocene. The sedimentary fill of the basin evolves from continental fluvio-lacustrine in the Palaeogene through to fully marine following the second phase of rifting in the Miocene. This pulsed structural and stratigraphic evolution has resulted in basinwide deposition of source, reservoir and seal facies, and produced a variety of potential trapping styles. This paper describes the hydrocarbon habitat of the south east Nam Con Son Basin within the context of the regional tectono-stratigraphic model.« less

Late Neogene sedimentary facies and sequences in the Pannonian Basin, Hungary

USGS Publications Warehouse

Juhasz, E.; Phillips, L.; Muller, P.; Ricketts, B.; Toth-Makk, A.; Lantos, M.; Kovacs, L.O.

1999-01-01

This paper is part of the special publication No.156, The Mediterranean basins: Tertiary extension within the Alpine Orogen. (eds B.Durand, L. Jolivet, F.Horvath and M.Seranne). Detailed sedimentological, facies and numerical cycle analysis, combined with magnetostratigraphy, have been made in a number of boreholes in the Pannonian Basin, in order to study the causes of relative water-level changes and the history of the basin subsidence. Subsidence and infilling of the Pannonian Basin, which was an isolated lake at that time occurred mainly during the Late Miocene and Pliocene. The subsidence history was remarkably different in the individual sub-basins: early thermal subsidence was interrupted in the southern part of the basin, while high sedimentation rate and continuous subsidence was detected in the northeastern sub-basin. Three regional unconformities were detected in the Late Neogene Pannonian Basin fill, which represent 0.5 and 7.5 Ma time spans corresponding to single and composite unconformities. Consequently two main sequences build up the Late Neogene Pannonian Basin fill: a Late Miocene and a Pliocene one. Within the Late Miocene sequence there are smaller sedimentary cycles most probably corresponding to climatically driven relative lake-level changes in the Milankovitch frequency band. Considering the periods, the estimated values for precession and eccentricity in this study (19 and 370 ka) are close to the usually cited ones. In the case of obliquity the calculated period (71 ka) slightly deviates from the generally accepted number. Based on the relative amplitudes of oscillations, precession (sixth order) and obliquity (fifth order) cycles had the most significant impact on the sedimentation. Eccentricity caused cycles (fourth order) are poorly detectable in the sediments. The longer term (third order) cycles had very slight influence on the sedimentation pattern. Progradation, recorded in the Late Miocene sequence, correlates poorly in time within the basin. The dominant controls of this process probably were changes of basin subsidence rate and the very high sedimentation rate. The slow, upward trend of silt and sand bed thickness as well as that of the grain size also reflects the local progradation.

Tectonic setting of Cretaceous basins on the NE Tibetan Plateau: Insights from the Jungong basin

USGS Publications Warehouse

Craddock, W.H.; Kirby, E.; Dewen, Z.; Jianhui, L.

2012-01-01

Quantifying the Cenozoic growth of high topography in the Indo-Asian collision zone remains challenging, due in part to significant shortening that occurred within Eurasia before collision. A growing body of evidence suggests that regions far removed from the suture zone experienced deformation before and during the early phases of Himalayan orogenesis. In the present-day north-eastern Tibetan Plateau, widespread deposits of Cretaceous sediment attest to significant basin formation; however, the tectonic setting of these basins remains enigmatic. We present a study of a regionally extensive network of sedimentary basins that are spatially associated with a system of SE-vergent thrust faults and are now exposed in the high ranges of the north-eastern corner of the Tibetan Plateau. We focus on a particularly well-exposed basin, located ~20km north of the Kunlun fault in the Anyemaqen Shan. The basin is filled by ~900m of alluvial sediments that become finer-grained away from the basin-bounding fault. Additionally, beds in the proximal footwall of the basin-bounding fault exhibit progressive, up-section shallowing and several intraformational unconformities which can be traced into correlative conformities in the distal part of the basin. The observations show sediment accumulated in the basin during fault motion. Regional constraints on the timing of sediment deposition are provided by both fossil assemblages from the Early Cretaceous, and by K-Ar dating of volcanic rocks that floor and cross-cut sedimentary fill. We argue that during the Cretaceous, the interior NE Tibetan Plateau experienced NW-SE contractional deformation similar to that documented throughout the Qinling-Dabie orogen to the east. The Songpan-Ganzi terrane apparently marked the southern limit of this deformation, such that it may have been a relatively rigid block in the Tibetan lithosphere, separating regions experiencing deformation north of the convergent Tethyan margin from regions deforming inboard of the east Asian margin. ?? 2011 The Authors. Basin Research ?? 2011 Blackwell Publishing Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists.

Early cretaceous topographic growth of the Lhasaplano, Tibetan plateau: Constraints from the Damxung conglomerate

NASA Astrophysics Data System (ADS)

Wang, Jian-Gang; Hu, Xiumian; Garzanti, Eduardo; Ji, Wei-Qiang; Liu, Zhi-Chao; Liu, Xiao-Chi; Wu, Fu-Yuan

2017-07-01

Constraining the timing of early topographic growth on the Tibetan plateau is critical for any models of India-Asia collision, Himalayan orogeny and subsequent plateau development in the Cenozoic. Stratigraphic, sedimentological and provenance analysis of the Lower Cretaceous red-beds of the Damxung Conglomerate provide new key information to reconstruct the paleogeography and the tectonic evolution of the Lhasa terrane at the time. The over 700-m-thick Damxung Conglomerate documents distal alluvial fan to braidplain sedimentation passing upward to proximal alluvial fan sedimentation. Deposition began near sea level, as documented by limestone beds occurring at the base of the unit. Zircon U-Pb dating of interbedded tuff layers constrain deposition age at ca. 111 Ma. Abundance of volcanic clasts, Cretaceous U-Pb ages and Hf isotopes of detrital zircons yielding mainly negative ɛHf(t) values together with paleocurrent data indicate an active volcanic source located in the North Lhasa subterrane. Pre-Mesozoic-aged zircon, recycled quartz and (meta) sedimentary rock fragments increase up-section, indicating progressive erosional exhumation of the Paleozoic sedimentary/metasedimentary basement. The Damxung Conglomerate thus records a significant uplift and unroofing stage in the source region, implying initial topographic growth on the Lhasa terrane at early Albian time. Early Cretaceous topographic growth on the Lhasa terrane is supported by the stratigraphic record in the Linzhou basin, the Xigaze forearc basin and the southern Nima basin. In contrast, marine strata in the central-western Lhasa terrane lasted until the early Cenomanian (ca. 96 Ma), indicating diachronous marine regression on the Lhasa terrane from east to west.

Scale dependant compensational stacking of channelized sedimentary deposits

NASA Astrophysics Data System (ADS)

Wang, Y.; Straub, K. M.; Hajek, E. A.

2010-12-01

Compensational stacking, the tendency for sediment transport system to preferentially fill topographic lows, thus smoothing out topographic relief is a concept used in the interpretation of the stratigraphic record. Recently, a metric was developed to quantify the strength of compensation in sedimentary basins by comparing observed stacking patterns to what would be expected from simple, uncorrelated stacking. This method uses the rate of decay of spatial variability in sedimentation between picked depositional horizons with increasing vertical stratigraphic averaging distance. We explore how this metric varies as a function of stratigraphic scale using data from physical experiments, stratigraphy exposed in outcrops and numerical models. In an experiment conducted at Tulane University’s Sediment Dynamics Laboratory, the topography of a channelized delta formed by weakly cohesive sediment was monitored along flow-perpendicular transects at a high temporal resolution relative to channel kinematics. Over the course of this experiment a uniform relative subsidence pattern, designed to isolate autogenic processes, resulted in the construction of a stratigraphic package that is 25 times as thick as the depth of the experimental channels. We observe a scale-dependence on the compensational stacking of deposits set by the system’s avulsion time-scale. Above the avulsion time-scale deposits stack purely compensationally, but below this time-scale deposits stack somewhere between randomly and deterministically. The well-exposed Ferris Formation (Cretaceous/Paleogene, Hanna Basin, Wyoming, USA) also shows scale-dependant stratigraphic organization which appears to be set by an avulsion time-scale. Finally, we utilize simple object-based models to illustrate how channel avulsions influence compensation in alluvial basins.

Zinc and Its Isotopes in the Loire River Basin, France

NASA Astrophysics Data System (ADS)

Millot, R.; Desaulty, A. M.; Bourrain, X.

2014-12-01

The contribution of human activities such as industries, agriculture and domestic inputs, becomes more and more significant in the chemical composition of the dissolved load of rivers. Human factors act as a supplementary key process. Therefore the mass-balance for the budget of catchments and river basins include anthropogenic disturbances. The Loire River in central France is approximately 1010 km long and drains an area of 117,800 km2. In the upper basin, the bedrock is old plutonic rock overlain by much younger volcanic rocks. The intermediate basin includes three major tributaries flowing into the Loire River from the left bank: the Cher, the Indre and the Vienne rivers; the main stream flows westward and its valley stretches toward the Atlantic Ocean. Here, the Loire River drains the sedimentary series of the Paris Basin, mainly carbonate deposits. The lower Loire basin drains pre-Mesozoic basement of the Armorican Massif and its overlying Mesozoic to Cenozoic sedimentary deposits. The Loire River is one of the main European riverine inputs to the Atlantic ocean. Here we are reporting concentration and isotope data for Zn in river waters and suspended sediments from the Loire River Basin. In addition, we also report concentration and isotope data for the different industrial sources within the Loire Basin, as well as data for biota samples such as mussels and oysters from the Bay of Biscay and North Brittany. These organisms are known to be natural accumulators of metal pollutants. Zinc isotopic compositions are rather homogeneous in river waters with δ66Zn values ranging from 0.21 to 0.39‰. This range of variation is very different from anthropogenic signature (industrial and/or agriculture release) that displays δ66Zn values between 0.02 to 0.14‰. This result is in agreement with a geogenic origin and the low Zn concentrations in the Loire River Basin (from 0.8 to 6 µg/L).

Does the sedimentology of the Chelmsford formation provide evidence for a meteorite impact origin of the Sudbury structure?

NASA Technical Reports Server (NTRS)

Long, D. G. F.

1992-01-01

The post-'event' fill of the Paleoproterozoic Sudbury Basin consists of at least 600 m of deep-water mudrocks of the Onwatin Formation, overlain by 850 m of lithic-arkosic muddy sandstones in the Chelmsford Formation. While mudstones of the Onwatin reflect deposition in a deep-water, anoxic setting, there is no clear evidence of local breccias, conglomerates, or sand bodies to support the concept that the basin was protected by the steep walls of an impact crater. Carbonates in the basal, Vermillion Member are of sedimentary exhalitive origin and were not derived from a shallow marine shelf. Turbidites in the Chelmsford Formation show no evidence of centripetal fill as might be expected from a restricted, circular basin. They appear to have been emplaced by predominantly southwesterly flowing turbidity currents, which showed little to no deflection along the depositional axis of an elongate foreland basin that developed in front of the rising Penokean mountain chain. While the presence of minor sandstone-filled fractures in parts of the Chelmsford Formation suggests the presence of north- or south-directed paleoslopes, no evidence is seen to support the existence of subbasins or a central uplift within the Sudbury Basin. While tilt-corrected paleocurrent orientations are ambiguous, due to postdepositional shortening of strata during cleavage development, strain correction of the observations makes little difference to the net, south-southwest-directed paleoflow.

Investigations of the petrogeneration zones western Bering sea by airborne geophysical data

NASA Astrophysics Data System (ADS)

Litvinova, T.; Petrova, A.

2012-04-01

In 2011, work continued on the interpretation of geophysical data in western Bering Sea. Bering Sea oil-and-gas bearing province occupies a single sedimentary megabasin of the Bering Sea, the formation of which is caused by stage of the Alpine geodynamic development cycle of the Pacific mobile belt. At present, the geological-geophysical exploration maturity of the Bering Sea with respect to oil-gasbearing prognosis is at the level of regional study stage. In 2003, an additional study of oil-gas prospective zones of the Kamchatka Shelf of the Bering Sea was carried out. In the course of works, profile seismic studies and airborne gravity-magnetic survey at 1:200,000 scale were made at three territories: Ilpinsky, Olyutorsky I, and Olyutorsky II. Average survey elevation for the whole area is 300 meters. Geological modeling of sedimentary basin systems was made for this area. Geomagnetic sections it possible to compare the location of the magnetic and weakly magnetic structures with seismic and geological boundaries marker and conducting layers of geoelectric sections. This makes it possible to trace the features of placing magnetic differences in the geologic rock section, to identify their stratigraphic association, select the layers flyuidstubborn, adumbrate reservoir heterogeneity and establish the heterogeneity of internal structure oil-gasbearing zones. Age correlation, thickness estimation and formational characteristics of litho-stratigraphic complexes building up sections are carried out. Geomagnetic deep sections transecting main zones of prospective oil-gas accumulation to airborne magnetic data. Distribution of magnetization in the development interval of potentially productive sandy strata at depths from 1 to 5 km is obtained. The most prospective zones of possible oil-gas accumulation are distinguished in the Olyutorsky and Ilpinsky sedimentary basins. At height of 400 km this minimum keeps the form that speaks about stability of a condition of the permeable zones supervising oil-gas-bearing.

Subsurface Permian reef complexes of southern Tunisia: Shelf carbonate setting and paleogeographic implications

NASA Astrophysics Data System (ADS)

Zaafouri, Adel; Haddad, Sofiene; Mannaî-Tayech, Beya

2017-05-01

2-D seismic reflection sections, borehole data as well as published and unpublished data have been investigated to reconstruct the paleogeography of southern Tunisia during Middle to Late Permian times. Paleogeographical reconstruction based on the integration of petroleum well data and 2-D seismic facies interpretation shows three main depositional areas with very contrasting sedimentary pile. These are 1) a subsiding basin; 2) an outer shelf carbonate, and 3) an inner shelf carbonate. Based on typical electric responses of reef buildups to seismic wave, we shall urge that during Middle Permian times, the outer carbonate shelf was subject of reef barrier development. Lithology evidences from core samples show that reef framework correspond mainly to fossiliferous limestone and dolomite. The WNW-ESE recognized reef barrier led between latitudes 33° 10‧ 00″N and 33° 20‧ 00″N. The Tebaga of Medenine outcrop constitutes the northern-edge of this barrier. Westward it may be extended to Bir Soltane area whereas its extension eastward is still to be determined. Biogenic buildups took place preferentially over faulted Carboniferous and lower Paleozoic paleohighs resulting likely from the Hercynian orogeny. The subsiding basin is located north of Tebaga of Medenine outcrop where Upper Permian sedimentary sequence is made entirely of 4000 m deep marine green silty shale facies. These are ascribed to unorganized and chaotic reflectors. Inner carbonate shelf facies succession corresponds to a typical interbedding of shallow marine carbonate deposits, shale, dolomite, and anhydrite inducing parallel-layered of strong amplitude and good continuity reflectors. Also within the inner carbonate shelf patch reef or reef pinnacles have been identified based on their seismic signature particularly their low vertical development as compared to reef complexes. Southward, towards Sidi Toui area, the Upper Permian depositional sequence thins out and bears witness of land influences as entailed by the increase of silicoclastic sedimentary supply and the lack of marine fossil.

Mio-Pliocene morphotectonic evolution of the Iranian Plateau: from outward expansion to incision and excavation

NASA Astrophysics Data System (ADS)

Ballato, Paolo; Heidarzadeh, Ghasem; Zeilinger, Gerold; Ghassemi, Mohammad; Cifelli, Francesca; Mattei, Massimo; Hassanzadeh, Jamshid; Balling, Philipp; Dunkl, István; Sudo, Masafumi; Mulch, Andreas; Strecker, Manfred

2015-04-01

Located along plate convergence zones, high orogenic plateaus form extensive and elevated morphotectonic provinces that are flanked by high mountain ranges at their margins. The Iranian Plateau (IP) is a prominent NW-SE striking (ca. 1500 km in length for a width of 140 to 260 km), elevated (> 50% lies between 1.5 and 2 km of elevation), mostly internally drained (at present ca. 55% has internal drainage), arid (mean annual precipitation ranging from 0.1 to < 0.5 m/yr), virtually aseismic and thick (crustal thickness up to 70 km) morphotectonic feature of the Arabia-Eurasia collision zone. The major backbones of the plateau are the Sanandaj Sirjan Zone, the Urumieh Dokhtar Magmatic Arc, and locally the High Zagros Mountains. Although the plateau must be younger than 18-17 Ma (based on uplifted marine deposits of the Qom Formation) very little is known about the mechanisms and timing of plateau vertical growth and lateral expansion. The northern IP is constituted by a series of mountain ranges and sedimentary basins, which have been excavated by the Qezel-Owzan a major river flowing into the Caspian Sea. This provides easy access to synorogenic sediments and hence makes this region an ideal location to decipher the tectono-stratigraphic and possibly topographic history of the IP. To address these goals we have designed a multidisciplinary strategy including characterization of synorogenic deposits (sedimentology and provenance) and establishment of a detailed chronostratigraphic framework (magnetostratigraphy and geochronology). Our data show that a wedging (to the NE) sedimentary body started developing from ~17 Ma during the deposition of the Upper Red Formation. Sediment provenance and magnetic lineations show that detritus was sourced from the interior of the plateau, suggesting that sedimentation was associated with the development of large regional drainage systems. At the same time, growth strata document intrabasinal contractional deformation between ~14.5 and 12.5 Ma. At ~10.5 Ma an increase in sediment flux into the basin occurred as documented by an extensive progradation (> 50 km of distance) of conglomerates in the distal sectors of the basin. This event was followed by basin uplift and erosion with a shift of the basin depocenter toward the outer margin of the plateau (to the N and NE; Zanjan and Mianeh basins). There, sedimentation lasted until fluvial incision and basin excavation of sub-horizontal sediments started sometime during the last 4 Ma. Overall, our data suggest that sedimentation took place in a contiguous foreland-basin system, most likely triggered by thrust stacking and topographic loading in the interior of the plateau from ~17 Ma. The outward N to NE-directed propagation of the deformation fronts (< 10.5 Ma) excised parts of the foreland, incorporating new basin sectors into the orogenic plateau and compartmentalizing the foreland into a contractional basin and range topography. This implies that the IP developed during crustal shortening and thickening processes and that sometime after 10.5 Ma the northern IP had reached a lateral size similar to the modern one.

Masirah Graben, Oman: A hidden Cretaceous rift basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beauchamp, W.H.; Ries, A.C.; Coward, M.P.

1995-06-01

Reflection seismic data, well data, geochemical data, and surface geology suggest that a Cretaceous rift basin exists beneath the thrusted allochthonous sedimentary sequence of the Masirah graben, Oman. The Masirah graben is located east of the Huqf uplift, parallel to the southern coast of Oman. The eastern side of the northeast-trending Huqf anticlinorium is bounded by an extensional fault system that is downthrown to the southeast, forming the western edge of the Masirah graben. This graben is limited to the east by a large wedge of sea floor sediments and oceanic crust, that is stacked as imbricate thrusts. These sediments/ophiolitesmore » were obducted onto the southern margin of the Arabian plate during the collision of the Indian/Afghan plates at the end of the Cretaceous. Most of the Masirah graben is covered by an allochthonous sedimentary sequence, which is complexly folded and deformed above a detachment. This complexly deformed sequence contrasts sharply with what is believed to be a rift sequence below the ophiolites. The sedimentary sequence in the Masirah graben was stable until further rifting of the Arabian Sea/Gulf of Aden in the late Tertiary, resulting in reactivation of earlier rift-associated faults. Wells drilled in the Masirah graben in the south penetrated reservoir quality rocks in the Lower Cretaceous Natih and Shuaiba carbonates. Analyses of oil extracted from Infracambrian sedimentary rocks penetrated by these wells suggest an origin from a Mesozoic source rock.« less

Fault evolution in the Potiguar rift termination, equatorial margin of Brazil

NASA Astrophysics Data System (ADS)

de Castro, D. L.; Bezerra, F. H. R.

2015-02-01

The transform shearing between South American and African plates in the Cretaceous generated a series of sedimentary basins on both plate margins. In this study, we use gravity, aeromagnetic, and resistivity surveys to identify architecture of fault systems and to analyze the evolution of the eastern equatorial margin of Brazil. Our study area is the southern onshore termination of the Potiguar rift, which is an aborted NE-trending rift arm developed during the breakup of Pangea. The basin is located along the NNE margin of South America that faces the main transform zone that separates the North and the South Atlantic. The Potiguar rift is a Neocomian structure located at the intersection of the equatorial and western South Atlantic and is composed of a series of NE-trending horsts and grabens. This study reveals new grabens in the Potiguar rift and indicates that stretching in the southern rift termination created a WNW-trending, 10 km wide, and ~ 40 km long right-lateral strike-slip fault zone. This zone encompasses at least eight depocenters, which are bounded by a left-stepping, en echelon system of NW-SE- to NS-striking normal faults. These depocenters form grabens up to 1200 m deep with a rhomb-shaped geometry, which are filled with rift sedimentary units and capped by postrift sedimentary sequences. The evolution of the rift termination is consistent with the right-lateral shearing of the equatorial margin in the Cretaceous and occurs not only at the rift termination but also as isolated structures away from the main rift. This study indicates that the strike-slip shearing between two plates propagated to the interior of one of these plates, where faults with similar orientation, kinematics, geometry, and timing of the major transform are observed. These faults also influence rift geometry.

Quantification of CO2 generation in sedimentary basins through carbonate/clays reactions with uncertain thermodynamic parameters

NASA Astrophysics Data System (ADS)

Ceriotti, G.; Porta, G. M.; Geloni, C.; Dalla Rosa, M.; Guadagnini, A.

2017-09-01

We develop a methodological framework and mathematical formulation which yields estimates of the uncertainty associated with the amounts of CO2 generated by Carbonate-Clays Reactions (CCR) in large-scale subsurface systems to assist characterization of the main features of this geochemical process. Our approach couples a one-dimensional compaction model, providing the dynamics of the evolution of porosity, temperature and pressure along the vertical direction, with a chemical model able to quantify the partial pressure of CO2 resulting from minerals and pore water interaction. The modeling framework we propose allows (i) estimating the depth at which the source of gases is located and (ii) quantifying the amount of CO2 generated, based on the mineralogy of the sediments involved in the basin formation process. A distinctive objective of the study is the quantification of the way the uncertainty affecting chemical equilibrium constants propagates to model outputs, i.e., the flux of CO2. These parameters are considered as key sources of uncertainty in our modeling approach because temperature and pressure distributions associated with deep burial depths typically fall outside the range of validity of commonly employed geochemical databases and typically used geochemical software. We also analyze the impact of the relative abundancy of primary phases in the sediments on the activation of CCR processes. As a test bed, we consider a computational study where pressure and temperature conditions are representative of those observed in real sedimentary formation. Our results are conducive to the probabilistic assessment of (i) the characteristic pressure and temperature at which CCR leads to generation of CO2 in sedimentary systems, (ii) the order of magnitude of the CO2 generation rate that can be associated with CCR processes.

Geology and tectonic development of the continental margin north of Alaska

USGS Publications Warehouse

Grantz, A.; Eittreim, S.; Dinter, D.A.

1979-01-01

The continental margin north of Alaska, as interpreted from seismic reflection profiles, is of the Atlantic type and consists of three sectors of contrasting structure and stratigraphy. The Chukchi sector, on the west, is characterized by the deep late Mesozoic and Tertiary North Chukchi basin and the Chukchi Continental Borderland. The Barrow sector of central northern Alaska is characterized by the Barrow arch and a moderately thick continental terrace build of Albian to Tertiary clastic sediment. The terrace sedimentary prism is underlain by lower Paleozoic metasedimentary rocks. The Barter Island sector of northeastern Alaska and Yukon Territory is inferred to contain a very thick prism of Jurassic, Cretaceous and Tertiary marine and nonmarine clastic sediment. Its structure is dominated by a local deep Tertiary depocenter and two regional structural arches. We postulate that the distinguishing characteristics of the three sectors are inherited from the configuration of the rift that separated arctic Alaska from the Canadian Arctic Archipelago relative to old pre-rift highlands, which were clastic sediment sources. Where the rift lay relatively close to northern Alaska, in the Chukchi and Barter Island sectors, and locally separated Alaska from the old source terranes, thick late Mesozoic and Tertiary sedimentary prisms extend farther south beneath the continental shelf than in the intervening Barrow sector. The boundary between the Chukchi and Barrow sectors is relatively well defined by geophysical data, but the boundary between the Barrow and Barter Island sectors can only be inferred from the distribution and thickness of Jurassic and Cretaceous sedimentary rocks. These boundaries may be extensions of oceanic fracture zones related to the rifting that is postulated to have opened the Canada Basin, probably beginning during the Early Jurassic. ?? 1979.