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1

Playlist: Sedimentology and Stratigraphy  

NSDL National Science Digital Library

A YouTube playlist created by Dr. Dawn Sumner of the University of California - Davis. This videos include short pieces from her lectures on sedimentology and stratigraphy as well as other videos she has found on YouTube about the subject.

Sumner, Dawn; Youtube

2

Relationships among sedimentology, stratigraphy, and diagenesis in the Proterozoic Thelon Basin, Nunavut, Canada: implications for  

E-print Network

Relationships among sedimentology, stratigraphy, and diagenesis in the Proterozoic Thelon Basin and paragenetic relationships vary systematically with sedimentology and stratigraphy of the Thelon and provide. Keywords: Diagenesis; Sedimentology; Thelon; Sequence stratigraphy; Hydrostratigraphy 0375-6742/03/$ - see

Hiatt, Eric E.

3

The Early Aptian of Aralar (northern Spain): stratigraphy, sedimentology, ammonite biozonation, and OAE1  

E-print Network

The Early Aptian of Aralar (northern Spain): stratigraphy, sedimentology, ammonite biozonation Stratigraphy Ammonite biozonation TOC Oceanic Anoxic Event 1 a b s t r a c t The stratigraphy, sedimentology. The sedimentology indicates general deposition in a shallow marine environment, corresponding to mixed siliciclastic

Gilli, Adrian

4

Sedimentology and sequence stratigraphy of reefs and carbonate platforms  

SciTech Connect

Classical sequence stratigraphy has been developed primarily from siliciclastic systems. Application of the concept to carbonates has not been as straightforward as was originally expected even though the basic tenets of sequence stratigraphy are supposed to be applicable to all depositional systems. Rather than force carbonate platforms into the straightjacket of a concept derived from another sediment family, this course takes a different tack. It starts out from the premise that sequence stratigraphy is a modern and sophisticated version of lithostratigraphy and as such is a sedimentologic concept. More sedimentology into sequence stratigraphy is the motto of the course and the red line that runs through the chapter of this book. The cook sets out with a review of sedimentologic in reference to petroleum deposits principles governing the large-scale anatomy of reefs and platforms. It then looks at sequences an systems tracts from a sedimentologic point of view, assesses the differences between siliciclastics and carbonates in their response to sea level, evaluates processes that compete with sea level for control on carbonate sequences, and finally presents a set of guidelines for application of sequence stratigraphy to reefs and carbonate platforms.

Schlager, W. (Free Univ., Amsterdam (NL))

1992-01-01

5

Reading and Abstracting Journal Articles in Sedimentology and Stratigraphy.  

ERIC Educational Resources Information Center

An assignment centered on reading journal articles and writing abstracts is an effective way to improve student reading and writing skills in sedimentology and stratigraphy laboratories. Each student reads two articles and writes informative abstracts from the author's point of view. (PR)

Conrad, Susan Howes

1991-01-01

6

Sedimentology and sequence stratigraphy of the Sturgeon Lake field, Alberta  

SciTech Connect

This study examines the sedimentology, sequence stratigraphy and reservoir characterization of the Lower Triassic Montney Formation in the Sturgeon Lake field located in west-central Alberta. The Montney Formation is grouped into two facies associations. Facies Association 1 is a siliciclastic upward-coarsening sequence deposited by storm, current and wave processes and is interpreted as a low energy progradational lower shoreface. Facies Association 2 is a carbonate shallowing upward sequence deposited in a wave dominated progradational shoreface. The contact between Facies Association 1 and 2 is marked by a major change in lithology and is erosive. Palynological analyses reveal two missing palynologic subzones between Facies Association 1 and Facies Association 2 suggesting a period of erosion and/or nondeposition. The boundary between the two facies association is defined as a sequence boundary which stratigraphically divides the Montney Formation into two sequences in the study area. The Lower Montney sequence is composed of eight retrogradational, aggradational and progradational parasequences and represent the Transgressive and the High-stand System Tract. The Upper Montney sequence is composed only of one parasequence and represents the Transgressive System Tract. The Sturgeon Lake Field has two types of reservoir with respect to lithology, porosity, permeability and geometry. The best reservoir facies is a brachiopod wackestone-packstone with permeabilities up to 8 Darcys. Siliciclastic reservoirs consist of very fine grained sandstones with permeabilities of 132 md when fractured.

Mederos, S.M. [Maraven, S.A., Caracas (Venezuela); Moslow, T.F. [Univ. of Alberta, Edmonton (Canada)

1996-08-01

7

Integrated Field Project in Structural Geology and Sedimentology/Stratigraphy  

NSDL National Science Digital Library

The field project described in the Big Horn Basin is a capstone experience for our innovative full-year course sequence that combines two geologic disciplines traditionally taught separately (in "silos") sedimentology/stratigraphy and structural geology. We feel that a holistic approach that combines an understanding of the processes involved in both disciplines allows students to more easily develop the geologic history of an area from collected field data. The result is a two-semester course sequence that integrates the concepts of the two disciplines through a full year of study. While we have more than ten different field projects during the year, these are simply "snapshots" that allow the student to only see a piece of the geologic puzzle. These exercises do develop skills that the student will use in the capstone experience the geologic synthesis of a specific region currently the Sheep Mountain region of the Big Horn Basin. The field-mapping project in the Big Horn Basin is followed by five weeks of sequenced work that allows each student to synthesize a complete geologic (sedimetologic and structural) history of the region. This includes the construction of a geologic map and cross-sections, understanding the depositional history (including environments of deposition), the syn- or post-depositional deformation of the region and an attempt to put the local geologic history into the context of regional deformation and tectonics. We believe that by integrating the disciplines into the two-semester sequence capped with the field mapping and synthesis better prepares students to "think like a geologist".

Malinconico, Lawrence

8

The Jurassic of Svalbard, Sedimentology, Stratigraphy and Paleontology  

NASA Astrophysics Data System (ADS)

During the Mesozoic the landmass now known as Svalbard drifted from 45oN to 65oN. The average global temperature was significantly higher, disabling the formation of icecaps at the poles, resulting in a higher sea-level. At the time the location now known as Svalbard was covered by a shallow ocean and mostly marine, organic rich, black shales, interrupted by possibly deltaic sediments were deposited. These sediments are rich in invertebrate fossils. A general description of the Agardhfjellet formation, spanning the middle to upper Jurassic, was made by Dypvik in 1991. Wierzbowski (1989) described some ammonites in detail from the Kimmeridgian. It is not known if the fauna extends further up or down in the formation. Since 2004 the Museum of Natural History of Oslo has been active in Spitsbergen Svalbard. Extensive and detailed sedimentological and stratigraphic research was never conducted as the focus lay on vertebrate fossils. A detailed sedimentological analysis, description and correlation to other Jurassic Formations (such as the Kimmeridge Shales, Hekkingen Formation and draupne Formation) is essential to better understand the circumstances where the black organic-rich shales (a highly potential source rock) were deposited in and to be able to predict their occurrences. Included in this description is taxonomy, taphonomy and the stratigraphic development of invertebrate fauna to pinpoint the age of the sediments.

Koevoets, Maayke; Hammer, Øyvind

2014-05-01

9

Contribution of logging data to sedimentology and stratigraphy. [Electrofacies  

SciTech Connect

A technique has been developed using multivariate analysis of logging data to give a high-resolution sedimentological description of any sequence of formations. The number of different logs and their range allow determination of many of the physical characteristics of the rock. The definition of a lithofacies has been extended by introducing the concept of an electrofacies, constructed on the basis of all the logging data at any depth interval. Each logging datum is considered a descriptor for purposes of establishing electrofacies in a logged interval. Once established, electrofacies then can be correlated with actual geologic facies, if the logged interval has been cored. 23 refs.

Serra, O.; Abbott, H.T.

1982-02-01

10

Carboniferous clastic-wedge stratigraphy, sedimentology, and foreland basin evolution: Black Warrior basin, Alabama and Mississippi  

SciTech Connect

Carboniferous clastic-wedge stratigraphy and sedimentology in the Black Warrior basin of Alabama and Mississippi indicate deposition in an evolving foreland basin flanking the Appalachian-Ouachita fold-thrust belt. The strata reflect specific responses to foreland basin subsidence, orogenic activity, sediment supply, and dispersal systems. Definition of the regional stratigraphy of the clastic wedge provides for interpretation of the foreland basin subsidence history by enabling quantitative reconstruction of regional compaction and subsidence profiles. Comparison of the interpreted subsidence history with model profiles of foreland basin subsidence (predicted from loading and flexure of continental lithosphere) allows evaluation of mechanical models in terms of observed clastic-wedge sedimentology and stratigraphy. Mechanical modeling of foreland basin subsidence predicts formation of a flexural bulge that migrates cratonward ahead of the subsiding foreland basin during loading. In the Black Warrior basin, local stratigraphic thins, pinch-outs, and areas of marine-reworked sediments suggest migration of the flexural bulge. Comparison of flexural bulge migration with thermal maturation history allows evaluation of timing of stratigraphic trapping mechanisms with respect to onset of hydrocarbon generation.

Hines, R.A.

1986-05-01

11

Stratigraphy, sedimentology and diagenesis of the Zechstein carbonate-evaporate cycles onshore northern Netherlands  

NASA Astrophysics Data System (ADS)

Although most gas volumes in northern Netherlands are produced from Rotliegend reservoirs, Late Permian Zechstein reservoirs have been an exploration target for the last decades. Most Zechstein gas reservoirs are found in the Zechstein 2 Carbonate Member, but some minor findings are reported from the platform facies of the thinner Zechstein 3 Carbonate Member. Such reservoirs overlain by thicker anhydrite beds may constitute profitable hydrocarbon reservoirs, but also represent a potential drilling hazard due to high fluid overpressures and/or unexpected brine chambers. This work aims to give an overview about the stratigraphy, sedimentology, and diagenesis of the Zechstein interval from the Zechstein 2 Salt to Zechstein 4 in order to evaluate the reservoir potential. The results of this work are based on observations of core samples, cuttings, thin sections, seismic data, and geophysical well logs as well as XRD analyses. Combined, these data were the basis to investigate the mineralogy and porosity of the Zechstein carbonate-evaporate cycles. The basin facies of the Z3 Carbonate Member consists of either aphanocrystalline dolomite or magnesite with high amounts of anhydrite, plugging pores and decreasing the reservoir potential. Some open pores and fractures were only found in Zechstein 2 anhydrite layers, whereas most pores are plugged with halite. A further focus is put on the origin, composition, and deformation of anhydrite intercalations (intra-salt stringers) fully embedded in the Zechstein 2 Salt Member as well as to salt tectonics affecting the study area, and structures pointing to former overpressures, like a younger clastic dike squeezed into the Zechstein, indicating a high-pressure regime.

Biehl, B. C.; Krejci, E.-M.; Reuning, L.; Strozyk, F.; Kukla, P.

2012-04-01

12

Sedimentology and stratigraphy of a tidal sand bank in the southern North Sea  

Microsoft Academic Search

A set of 125 vibrocores collected on the basis of a dense grid of high and very high resolution seismic coverage over a tidal sand bank (the Middelkerke Bank) provides a unique opportunity to reconstruct the stratigraphy and sedimentary facies succession of such a large tidal sand body. Five sedimentary facies are distinguished. They range from clay to pebble and

Alain Trentesaux; Ad Stolk; Serge Berné

1999-01-01

13

Stratigraphy, sedimentology, chronology and palaeohydrology of Quaternary lacustrine deposits at Madigan Gulf, Lake Eyre, south Australia  

Microsoft Academic Search

Madigan Gulf is a large bay at the southern end of Lake Eyre North, a major ephemerally flooded playa in arid central Australia at the southwestern margin of a vast (1,300,000 km2) internal drainage basin. The stratigraphy and chronology of the Quaternary sequence in the gulf is described from 8 cores and a cliff exposure at the gulf margin. A

J. W. Magee; J. M. Bowler; G. H. Miller; D. L. G. Williams

1995-01-01

14

Stratigraphy, chronology, and sedimentology of ignimbrites from the white trachytic tuff, Roccamonfina Volcano, Italy  

Microsoft Academic Search

We describe the stratigraphy, chronology, and grain size characteristics of the white trachytic tuff (WTT) of Roccamonfina Volcano (Italy). The pyroclastic rock was emplaced between 317 and 230 Ma BP during seven major eruptive events (units A to G) and three minor events (units BC, CD, and DE). These units are separated by paleosol layers and compositionally well-differentiated pyroclastic successions.

Bernardino Giannetti; Giancarlo De Casa

2000-01-01

15

Integration of sequence stratigraphy and process sedimentology: Miocene Rincon and Topanga Formations, Santa Barbara basin near Point Mugu, California  

SciTech Connect

The Miocene Rincan and Topanga formations exposed at Point Mugu comprise over 1,200 ft of interbedded sandstones, siltstones, claystones, and clay shales that were deposited in a tectonically active marine basin adjacent to the present Santa Monica Mountains. Integration of sequence stratigraphic interpretation techniques and process sedimentology demonstrates that this section originated as shelfal deposits during sea level rise that were cut by a submarine canyon during subsequent sea level lowstand. The base of the sequence contains a bioturbated silty sandstone indicative of a transgressive deposit within the sequence stratigraphic framework. Upsection, dark clay shales of a condensed section contain fish fragments and sponge progradational highstand shelf sandstones. An erosional surface flooring a deep-water canyon cuts the highstand deposits and marks a sequence boundary. Within the submarine canyon fill, deep-water deposits represent at least two episodes of sediment gravity flows. A predominantly deformed lower section is cut by an erosional surface (another sequence boundary ) overlain by undeformed strata. The deformed section was caused by slumping of a canyon wall within a slope environment and deposition of high-density turbidites and debris flows. The undeformed section contains Bouma sequences, graded beds, dish structures, and biogenic structures. Interstratified bed-thinning and bed-thickening sequences suggest minor progradational events and small feeder channels within the undeformed section. These relationships demonstrate that not all sequences comprising deep-water deposits can be easily assigned to facies, such as channels and lobes, based on vertical and lateral profiles. This integration of sequence stratigraphy and sedimentology has assisted in understanding the vertical and lateral heterogeneities present within exploration and production areas in the adjacent Santa Barbara Channel.

Jordan, D.W.; Marquard, R.S. (ARCO Oil and Gas Co., Plano, TX (USA))

1990-05-01

16

Sedimentology, stratigraphy, and extinctions during the Cretaceous-Paleogene transition at Bug Creek, Montana  

NASA Astrophysics Data System (ADS)

Bug Creek Valley, the source of an unusual and controversial Cretaceous-Paleogene coincidence of mammals, dinosaurs, pollen, and indium, exemplifies the importance of depositional process in the reconstruction of evolutionary events. Five sedimentary facies are recognized at Bug Creek: a cross-stratified sandstone, a green and purple siltstone, a lateral accretionary sandstone, a coal, and a variegated siltstone. Repeated fluvial channeling restricts the accuracy of lateral correlations, and the relationship of the fossil assemblage to the presumed Cretaceous-Paleogene boundary cannot be established. Sedimentologically, the Cretaceous-Paleogene transition is represented here by Cretaceous meandering channels that gave way initially to Paleogene swamp deposition.

Fastovsky, David E.; Dott, Robert H., Jr.

1986-04-01

17

Sedimentology, stratigraphy, and extinctions during the Cretaceous-Paleogene transition at Bug Creek, Montana  

SciTech Connect

Bug Creek Valley, the source of an unusual and controversial Cretaceous-Paleogene coincidence of mammals, dinosaurs, pollen, and iridium, exemplifies the importance of depositional process in the reconstruction of evolutionary events. Five sedimentary facies are recognized at Bug Creek: a cross-stratified sandstone, a green and purple siltstone, a lateral accretionary sandstone, a coal, and a variegated siltstone. Repeated fluvial channeling restricts the accuracy of lateral correlations, and the relationship of the fossil assemblage to the presumed Cretaceous-Paleogene boundary cannot be established. Sedimentologically, the Cretaceous-Paleogene transition is represented here by Cretaceous meandering channels that gave way initially to Paleogene swamp deposition. 13 references, 4 figures.

Fastovsky, D.E.; Dott, R.H. Jr.

1986-04-01

18

Sedimentology and stratigraphy of the Queen Formation, Millard Field, Pecos County, Texas  

E-print Network

of the Permian Basin of west Texas and New Mexico. The regional structure and stratigraphy of the Permian Basin are well established; however, because published subsurface studies of the Queen Formation are rar e, specific information on depositional..., to establish a model of deposit1on, subsequent cementation, and diagenesis. The Millard Field in Pecos County, Texas produces from the queen Format1on and provides such an area to study the format1on. GEOLOGIC SETTING Structure The Permian Basin reg1on...

Williams, Matt Brian

1984-01-01

19

Stratigraphy and sedimentology of the K/T boundary deposit in Haiti  

NASA Technical Reports Server (NTRS)

The K/T boundary sequence is exposed in uplifted carbonate sediments of the southwest peninsula of Haiti. It is found at 15 localities within the Beloc formation, a sequence of limestone and marls interpreted as a monoclinal nappe structure thrust to the north. This tectonic deformation has affected the K/T boundary deposit to varying degrees. In some cases the less competent K/T deposit has acted as a slip plane leading to extensive shearing of the boundary layer, as well as duplication of the section. The presence of glassy tektites, shocked quartz, and an Ir anomaly directly link the deposit to a bolide impact. Stratigraphic and sedimentological features of the tripartite sequence indicate that it was formed by deposition from ballistic fallout of coarse tektites, emplacement of particle gravity flows and fine grained fallout of widely dispersed impact ejecta.

Carey, S.; Sigurdsson, H.; Dhondt, S.; Espindola, J. M.

1993-01-01

20

The Mud Hills, Mojave Desert, California: Structure, stratigraphy and sedimentology of a rapidly extended terrane  

SciTech Connect

The Mud Hills exposes synorogenic breccia (Mud Hills Fm.) deposited during the final stages of crustal extension of the upper plate above the Waterman Hills detachment (20--18 Ma). Previous workers have misinterpreted fault contacts as stratigraphic contacts, and have developed intricate pseudostratigraphy to explain their observations. The authors' detailed mapping, combined with stratigraphic and sedimentologic data, documents that the volcaniclastic Pickhandle Fm. is conformably overlain by the plutoniclastic Mud Hills Fm., with no interfingering. Repetition of these south-dipping lithologic units is due to imbricate, north-dipping listric faults. These relations are demonstrated by the systematic northward v''ing of fault contacts and southward v''ing of stratigraphic contacts. Stratigraphic dip decreases upsection, which is consistent with incremental rotation of basinal strata simultaneously with deposition. Most of the Mud Hills Fm. consists of rock-avalanche breccia and megabreccia derived from granodiorite, which is identical to basement exposed beneath the Pickhandle and Jackhammer Fms. to the north. The Mud Hills Fm. was derived from now-buried granodiorite of a stranded upper-plate block to the south, as demonstrated by northward paleocurrents, facies relations and the presence of fine-grained units close to the presumed master fault (as is typical of half-graben sedimentation). Unconformably overlying the Mud Hills Fm. is the Owl Conglomerate (Barstow Fm.), which has mixed provenance with southward paleocurrents; the Owl Conglomerate was derived from residual highlands after extension ceased. Integration of structural, stratigraphic and sedimentologic information is essential for correct reconstruction of highly extended terranes.

Ingersoll, R.V.; Devaney, K.A.; Geslin, J.K.; Cavazza, W.; Diamond, D.S.; Jagiello, K.J.; Marsaglia, K.M.; Paylor, E.D. II; Short, P.F. (Univ. of California, Los Angeles, CA (United States). Dept. of Earth and Space Sciences)

1993-04-01

21

Stratigraphy, sedimentology and tectonic evolution of the Upper Cretaceous/Paleogene succession in north Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The stratigraphy, sedimentology and syn-depositional tectonic events (SdTEs) of the Upper Cretaceous/Paleogene (K-P) succession at four localities in north Eastern Desert (NED) of Egypt have been studied. These localities are distributed from south-southwest to north-northeast at Gebel Millaha, at North Wadi Qena, at Wadi El Dakhal, and at Saint Paul Monastery. Lithostratigraphically, four rock units have been recorded: Sudr Formation (Campanian-Maastrichtian); Dakhla Formation (Danian-Selandian); Tarawan Formation (Selandian-Thanetian) and Esna Formation (Thanetian-Ypresian). These rock units are not completely represented all over the study area because some of them are absent at certain sites and others have variable thicknesses. Biostratigrapgically, 18 planktonic foraminiferal zones have been recorded. These are in stratigraphic order: Globotruncana ventricosa Zone (Campanian); Gansserina gansseri, Contusotruncana contusa, Recimguembelina fructicosa, Pseudohastigerina hariaensis, Pseudohastigerina palpebra and Plummerita hantkenenoides zones (Maastrichtian); Praemurica incostans, Praemurica uncinata, Morozovella angulata and Praemurica carinata/Igorina albeari zones (Danian); Igorina albeari, Globanomanlina pseudomenradii/Parasubbotina variospira, Acarinina subsphaerica, Acarinina soldadoensis/Globanomanlina pseudomenardii and Morozovella velascoensis zones (Selandian/Thantian); and Acarinina sibaiyaensis, Pseudohastigerina wilcoxensis/Morozovella velascoensis zones (earliest Ypresian). Sedimentologically, four sedimentary facies belts forming southwest gently-dipping slope to basin transect have been detected. They include tidal flats, outer shelf, slumped continental slope and open marine hemipelagic facies. This transect can be subdivided into a stable basin plain plus outer shelf in the extreme southwestern parts; and an unstable slope shelf platform in the northeastern parts. The unstable slope shelf platform is characterized by open marine hemipelagic, fine-grained limestones and fine siliciclastic shales (Sudr, Dakhla, Tarawan and Esna formations). The northeastern parts are marked by little contents of planktonic foraminifera and dolomitized, slumped carbonates, intercalated with basinal facies. Tectonically, four remarkable syn-depositional tectonic events (SdTEs) controlled the evolution of the studied succession. These events took place strongly within the Campanian-Ypresian time interval and were still active till Late Eocene. These events took place at: the Santonian/Campanian (S/C) boundary; the Campanian/Maastrichtian (C/M) boundary; the Cretaceous/Paleogene (K/P) boundary; and the Middle Paleocene-Early Eocene interval. These tectonic events are four pronounced phases in the tectonic history of the Syrian Arc System (SAS), the collision of the Afro-Arabian and Eurasian plates as well as the closure of the Tethys Sea.

El Ayyat, Abdalla M.; Obaidalla, Nageh A.

2013-05-01

22

Stratigraphy, sedimentology and paleontology of lower Eocene San Jose formation, central San Juan basin, New Mexico  

SciTech Connect

The lower Eocene San Jose Formation in the central portion of the San Juan basin (Gobernador-Vigas Canyon area) consists of the Cuba Mesa, Regina, Llaves, and Tapicitos Members. Well log data indicate that, from its 100-m thickness, the Cuba Mesa Member thins toward the basin center and pinches out to the northeast by lat. 36{degree}40'N, long. 107{degree}19'W. The Regina Member has the most extensive outcrops in the central basin, and it decreases in sandstone/mud rock ratio to the north. The Llaves and Tapicitos Members occur only at the highest elevations, are thin due to erosion, and are not mappable as separate units. Well log data and 1,275 m of measured stratigraphic section in the Regina, Llaves, and Tapicitos Members indicate these strata are composed of approximately 35% medium to coarse-grained sandstone and 65% fine-grained sandstone and mud rock. Sedimentology and sediment-dispersal patterns indicate deposition by generally south-flowing streams that had sources to the northwest, northeast, and east. Low-sinuosity, sand-bedded, braided( ) streams shifted laterally across about 1 km-wide channel belts to produce sheet sandstones that are prominent throughout the San Jose Formation. Subtle levees separated channel environments from floodplain and local lacustrine areas. Avulsion relocated channels periodically to areas on the floodplain, resulting in the typically disconnected sheet sandstones within muddy overbank deposits of the Regina Member.

Lucas, S.G.; Smith, L.N. (New Mexico Museum of Natural History, Albuquerque (USA))

1989-09-01

23

Sedimentology and stratigraphy of tidal sand ridges southwest Florida inner shelf  

SciTech Connect

Detailed investigation of linear shelf sand ridges located off the southwest coast of Florida shows them to be tide-dominated sand bodies. These ridges are remarkably similar to the large sand ridges of the North Sea, and they have abundant apparent analogs in the stratigraphic record, many of which are important petroleum producers. The Florida ridges are asymmetric in profile, about 10 km long, 1 km wide, with relief of 3-4 m with the adjacent sea bed. Extensive tidal current monitoring, sediment distribution patterns and side scan sonar surveys permit characterizing their morphodynamics. Tidal currents show distinct bidirectional patterns with speeds up to 70 cm/s. There is slight flood-dominance, and currents show much higher velocities in the troughs as compared to the crests of the ridges. Megaripples and sand waves are widespread and migrate obliquely across the ridges at opposite directions on the gentle and steep side of the ridge. Shallow, high-resolution seismic data and 39 vibracores din the area of the ridges show a consistent sequence characterized by three ascending Holocene lithofacies: (1) muddy quartz sand with limestone clasts; (2) bioturbated muddy shelly quartz sand; and (3) well-sorted, cross-stratified quartz sand that characterizes the sand ridges themselves. Each of the tidal sand ridges displays a coarsening-upward sequence of fine, well-sorted sand. Small-scale, multidirectional, cross stratification dominates the stratigraphy of the cores in this facies, but megaripple cross stratification is also present. All data indicate that these tidal ridges are good modern analogs for many of the shelf sand bodies in the ancient record, especially the Mesozoic of the mid-continent area.

Davis, R.A. Jr.; Klay, J.; Jewell, P. (Univ. of South Florida, Tampa (United States))

1993-01-01

24

Sedimentology, stratigraphy, and micropalaeontology of the Upper Triassic reefal series in Eastern Sulawesi (Indonesia)  

Microsoft Academic Search

An Upper Triassic (Upper Norian-Rhaetian) carbonate complex, composed of open marine to reefal deposits, has been investigated for the first time in Eastern Sulawesi. The age is based on the occurrence of benthic foraminifera, and also of the Upper Sevatian to Rhaetian conodont Misikella posthernsteini Kozur and Mock. Palynological assemblages contain Upper Triassic-Lower Jurassic palynomorphs. The scleractinian coral Retiophyllia seranica

Rossana Martini; Daniel Vachard; Louisette Zaninetti; Simonetta Cirilli; Jean-Jacques Cornée; Bernard Lathuilière; Michel Villeneuve

1997-01-01

25

Sedimentology and petroleum geology  

SciTech Connect

This book presents an introduction to sedimentology as well as petroleum geology. It integrates both subjects, which are closely related but mostly treated separately. The author covers the basic aspects of sedimentology, sedimentary geochemistry and diagenesis. Principles of stratigraphy, seismic stratigraphy and basin modelling forms the base for the part on petroleum geology. Subjects discussed include the composition of kerogen and hydrocarbons, theories of migration and trapping of hydrocarbons and properties of reservoir rocks. Introductions to well logging and production geology are given.

Bjorlykke, K.O. (Oslo Univ. (Norway))

1989-01-01

26

Stratigraphy, sedimentology and structure of the Numidian Flysch thrust belt in northern Tunisia  

NASA Astrophysics Data System (ADS)

The Oligo-Miocene Numidian Flysch of northern Tunisia has long been divided into three distinct lithostratigraphic units considered as vertically superimposed: the lower unit or the "Zouza member", the middle unit or the "Kroumirie member" and the upper unit or the "Babouch member". According to this reconstruction the two first members are mostly Oligocene in age and only the third member was assigned as early Miocene in age. In this study, we present new biostratigraphic data, based on planktonic foraminiferal analysis, demonstrating that both the Zouza and the Kroumirie members are Oligocene-early Miocene in age and are, therefore, coeval. Four distinct facies associations have been identified within the Numidian Flysch including: (a) massive sandstones; (b) conglomerate; (c) an interbedded mudstone-sandstone association; and (d) a mudstone facies association. Slide-slump units and injectionite sands occur within the more mud-rich associations. The likely depositional setting is a muddy slope-apron system, cut locally by sand-rich channels, which fed channel-terminal lobe deposits. Paleocurrent data support strongly a flow from N and NW. Modal analysis, demonstrates that the Numidian sandstones are quartz-arenite type (QFL, 97.25:1.25:1.5) derived from middle to high grade-metamorphic and granitic rocks. Zircon geochronology, yielding ages of 514 ± 19 Ma from Tunisia and 550 ± 28 Ma from Sicily, would support the basement terrain that crops out along the Algerian coast and forms part of Calabro-Peloritani-Kabylian zone, as the most likely parental source of the Numidian Flysch for both Sicily and Tunisia. Zircon data from the Fortuna Formation yields ages of 1698 ± 67 Ma, which is more compatible with an African craton source ( Fildes et al., 2009). Structural consideration of the basal contact of the Numidian Flysch with the underlying Tellian rocks, as well as newly interpreted seismic data; confirm the allochthounous position of the Numidian complex and its displacement southward. Facies comparison with the equivalent Oligo-Miocene Bejaoua siliciclastic deposits outcropping towards the south shows that the Numidian complex is an "out-of-sequence thrust unit" and that the two Oligo-Miocene sedimentary systems are quite distinct and were sourced from wholly different source regions.

Sami, Riahi; Soussi, Mohamed; Kamel, Boukhalfa; Kmar, Ben Ismail Lattrache; Stow, Dorrik; Sami, Khomsi; Mourad, Bedir

2010-04-01

27

Stratigraphy, sedimentology and eruptive mechanism of the El Golfo phreatomagmatic edifice (Lanzarote, Canary Islands)  

NASA Astrophysics Data System (ADS)

The El Golfo tuff cone is an example of phreatomagmatic edifice, developed in the western coast of Lanzarote (Canary Islands). El Golfo, together with other edifices of the same age, is aligned along a fracture oriented NEE-SWW coinciding with the main lineation of the historic volcanism in this part of the island. In this contribution we present a detailed stratigraphic study of the succession of deposits and we interpret them in terms of depositional processes and eruptive dynamics. The eruptive sequence is exclusively represented by a succession of pyroclastic deposits, and we infer it according to variations in flow regime and the magma-water interaction. Several pyroclastic units were identified according to facies variations based on sedimentary discontinuities, grain size, components, variations in primary laminations and bedforms following the facies model proposed by Chough and Sohn (1990). The growth of the El Golfo tuff cone involved several stages based on variations in depositional processes. The edifice was constructed very rapidly around the vent controlling the amount of water that got access to the eruption conduit. Although the invariable phreatomagmatic character of most of the pyroclastic sequence, it is possible to deduce variations in the explosive energy, with a general increment upwards, according to the increase in the degree of fragmentation of pyroclasts, The absence of hyaloclastites, the nature of the palagonite alteration and the observed sedimentary structures, demonstrate the subaereal character of most of the deposits

Pedrazzi, D.; Marti, J.; Geyer, A.

2012-04-01

28

Name: _____________________________________ Sedimentology & Stratigraphy  

E-print Network

. [10 points] 10. Please draw below a cross-sectional profile of a meandering stream, using a section. On this profile please label the following features -- [10 points] thalweg point bar erosional side cut bank

Wilson, Mark A.

29

Upper Pleistocene to Holocene peatland evolution in Southern Brazilian highlands as depicted by radar stratigraphy, sedimentology and palynology  

NASA Astrophysics Data System (ADS)

Paleoenvironmental interpretation of proxy data derived from peatlands is largely based upon an evolutionary model for ombrotrophic bogs, in which peat accumulates in still environments. Reports on proxies obtained from minerotrophic fens, where hydrologic inputs are variable, are less common. In this study, a highland peatland in southern Brazil is presented through ground penetrating radar (GPR) and sedimentological, palynological and geochronologic data. The radar stratigraphic interpretation suggests a relatively complex history of erosion and deposition at the site since the beginning of Marine Isotope Stage 3 (MIS 3) interstadial period. In spite of this, radar stratigraphic and palynologic interpretations converge. Electromagnetic reflections tend to group in clusters that show lateral coherence and correlate with different sediment types, while pollen grains abound and are well preserved. As a result, the study of minerotrophic fens provides a source of proxies, suggesting that ombrotrophic bogs are not the only reliable source of data in wetlands for palynological analysis.

de Oliveira, Marcelo Accioly Teixeira; Porsani, Jorge Luis; de Lima, Gisele Leite; Jeske-Pieruschka, Vivian; Behling, Hermann

2012-05-01

30

University of Minnesota: Sedimentology Group  

NSDL National Science Digital Library

The sedimentology group at the University of Minnesota presents its research in earthscape processes at this website. Visitors can find out about the goals, results, and publications of three main research areas: experimental stratigraphy and landscape evolution, theoretical sedimentology and stratigraphy, and river dynamics. The site offers downloads for many of the group's publications. Visitors discover the latest sedimentology-related news. While the links Useful Things and Links do not contain information at this time, users can still learn about the work of sedimentologists at this website.

31

Late Quaternary stratigraphy, sedimentology, and geochemistry of an underfilled lake basin in the Puna (north-west Argentina)  

USGS Publications Warehouse

Depositional models of ancient lakes in thin-skinned retroarc foreland basins rarely benefit from appropriate Quaternary analogues. To address this, we present new stratigraphic, sedimentological and geochemical analyses of four radiocarbon-dated sediment cores from the Pozuelos Basin (PB; northwest Argentina) that capture the evolution of this low-accommodation Puna basin over the past ca. 43 cal kyr. Strata from the PB are interpreted as accumulations of a highly variable, underfilled lake system represented by lake-plain/littoral, profundal, palustrine, saline lake and playa facies associations. The vertical stacking of facies is asymmetric, with transgressive and thin organic-rich highstand deposits underlying thicker, organic-poor regressive deposits. The major controls on depositional architecture and basin palaeogeography are tectonics and climate. Accommodation space was derived from piggyback basin-forming flexural subsidence and Miocene-Quaternary normal faulting associated with incorporation of the basin into the Andean hinterland. Sediment and water supply was modulated by variability in the South American summer monsoon, and perennial lake deposits correlate in time with several well-known late Pleistocene wet periods on the Altiplano/Puna plateau. Our results shed new light on lake expansion–contraction dynamics in the PB in particular and provide a deeper understanding of Puna basin lakes in general.

McGlue, Michael M.; Cohen, Andrew S.; Ellis, Geoffrey S.; Kowler, Andrew L.

2013-01-01

32

Stratigraphy and sedimentology of pre-late Wisconsin catastrophic glacial flood sediments, western Walla Walla Valley, Washington  

SciTech Connect

The Cummins Bridge site in the western Walla Walla Valley exhibits clear evidence for pre-late Wisconsin catastrophic glacial flooding. The section consists of an unstratified, poorly sorted diamict with angular basaltic clasts in a matrix of sand and silt, and a large number of well-rounded clasts of exotic lithology in the coarse fraction, gradationally overlain by a coarse, angular gravel that is matrix poor and exotic-free; this unit grades upward into a matrix-rich diamict with a well-developed caliche in the upper portion. Above this is a sand and silt unit showing vague cross-stratification, lamination, and graded beds; this unit may represent local temporary ponding of the ancestral drainage. Overlying this on a pronounced erosional surface are rhythmically stratified sand-to-salt beds assigned to the late Wisconsin Toughet Beds. The section is capped by a thin bed of Holocene loess. Stratigraphic and sedimentologic criteria suggest that the lowermost units represent an indirect record of catastrophic glacial flooding. Flood sediments were deposited on an adjacent topographic high and subsequently mass-wasted via mudflow into their present position. Normal fluvial processes alternated with mass-wasting events to concentrate the angular, matrix-poor basaltic gravel. The lower diamict shows characteristics similar to documented pre-late Wisconsin catastrophic flood sediments at a nearby site, including rounded exotic clasts, angular basaltic clasts, lack of stratification, and poor sorting. The two sites may represent the same pre-late Wisconsin flood event.

Robertson, J.L.; Spencer, P.K. (Whitman College, Walla Walla, WA (United States). Geology Dept.)

1993-04-01

33

Stratigraphy and Isotope Ages of Lunar Geologic Units: Chronological Standard for the Inner Solar System  

Microsoft Academic Search

The absolute ages of cratered surfaces in the inner solar system, including Mars, are derived by extrapolation from the impact flux curve for the Moon which has been calibrated on the basis of absolute ages of lunar samples. We reevaluate the lunar flux curve using isotope ages of lunar samples and the latest views on the lunar stratigraphy and the

D. Stöffler; G. Ryder

2001-01-01

34

Taconic foreland basin evolution: Sedimentology and cement stratigraphy of the Black River Group limestones in the Champlain Basin  

SciTech Connect

The Black River Group (Middle Ordovician, Mohawkian Series) limestones in the Champlain Basin record the transition between the shallow deposits of the underlying Chazy Group limestones and the shale-limestone couplets of the overlying Trenton Group which record rapid deepening of the foreland basin. The Black River Group was deposited in a subsiding foreland basin during the early stages of the Taconic Orogeny. Syn-depositional block faulting as a result of thrust loading has been demonstrated to affect Chazy and Trenton Group deposition. Abrupt lithofacies changes within the Black River Group record the dynamic bathymetry present in the Champlain Basin during its deposition. The Black River Group helps refine the timing of extensional block faulting during the Taconic Orogeny. The Black River Group in the Champlain Basin is a relatively thin unit, approximately 80 feet thick at Crown Point, New York. Exposures between Crown Point, NY and South Hero Island, VT record deposition of the Black River Group limestones in a protected lagoonal environment, with an evolving fringing pellet shoal barrier complex. Eight lithofacies are defined, grading from a basal sandstone and/or a sandy dolomite, to a micrite to biomicrite, to an intra-pelsparite of a shoal environment. Intraclast horizons and broken, rounded marine allochems suggest the influence of storm activity as a modifier of depositional history. Rapid deepenings into the normal marine subtidal environment, as well as micro-karst textures and fossil beach rock exposures are interpreted to represent sudden bas level changes, possibly from syndepositional block fault movement. Although dynamic bathymetry influences the stratigraphy within the Black River Group, a macro-scale deepening upwards on a formation scale is present, representing subsidence of the foreland basin.

Bechtel, S.C.; Mehrtens, C.J. (Univ. of Vermont, Burlington, VT (United States). Geology Dept.)

1993-03-01

35

Ages and stratigraphy of mare basalts in Oceanus Procellarum, Mare Nubium, Mare Cognitum, and Mare Insularum  

E-print Network

Ages and stratigraphy of mare basalts in Oceanus Procellarum, Mare Nubium, Mare Cognitum, and Mare July 2003. [1] Accurate estimates of mare basalt ages are necessary to place constraints on the duration and the flux of lunar volcanism as well as on the petrogenesis of lunar mare basalts

Head III, James William

36

Sedimentology and petroleum geology  

SciTech Connect

In this introduction to sedimentology and petroleum geology the subjects, which are closely related but mostly treated separately, are integrated. The first part covers the basic aspects of sedimentology, sedimentary geochemistry and diagenesis, including brief discussions of flow in rivers and channels, types of sediment transport, lake and river deposits, deltas (river-dominated, tide-dominated, and wave-dominated) and the water budget. Principles of stratigraphy, seismic stratigraphy and basin modeling form the basis for the last part on petroleum geology. Here subjects include the composition of kerogen and hydrocarbons, theories of migration and trapping of hydrocarbons and properties of reservoir rocks. Finally, short introductions to well logging and production geology are given.

Bjorlykke, K.

1989-01-01

37

Applied Stratigraphy  

NASA Astrophysics Data System (ADS)

Stratigraphy is a cornerstone of the Earth sciences. The study of layered rocks, especially their age determination and correlation, which are integral parts of stratigraphy, are key to fields as diverse as geoarchaeology and tectonics. In the Anglophile history of geology, in the early 1800s, the untutored English surveyor William Smith was the first practical stratigrapher, constructing a geological map of England based on his own applied stratigraphy. Smith has, thus, been seen as the first “industrial stratigrapher,” and practical applications of stratigraphy have since been essential to most of the extractive industries from mining to petroleum. Indeed, gasoline is in your automobile because of a tremendous use of applied stratigraphy in oil exploration, especially during the latter half of the twentieth century. Applied stratigraphy, thus, is a subject of broad interest to Earth scientists.

Lucas, Spencer G.

38

Mars north polar deposits: stratigraphy, age, and geodynamical response  

USGS Publications Warehouse

The Shallow Radar (SHARAD) on the Mars Reconnaissance Orbiter has imaged the internal stratigraphy of the north polar layered deposits of Mars. Radar reflections within the deposits reveal a laterally continuous deposition of layers, which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice. The packet/interpacket structure can be explained by approximately million-year periodicities in Mars' obliquity or orbital eccentricity. The observed ???100-meter maximum deflection of the underlying substrate in response to the ice load implies that the present-day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers. Alternatively, the response to the load may be in a transient state controlled by mantle viscosity. Both scenarios probably require that Mars has a subchondritic abundance of heat-producing elements.

Phillips, R.J.; Zuber, M.T.; Smrekar, S.E.; Mellon, M.T.; Head, J.W.; Tanaka, K.L.; Putzig, N.E.; Milkovich, S.M.; Campbell, B.A.; Plaut, J.J.; Safaeinili, A.; Seu, R.; Biccari, D.; Carter, L.M.; Picardi, G.; Orosei, R.; Surdas, Mohit P.; Heggy, E.; Zurek, R.W.; Egan, A.F.; Giacomoni, E.; Russo, F.; Cutigni, M.; Pettinelli, E.; Holt, J.W.; Leuschen, C.J.; Marinangeli, L.

2008-01-01

39

Mars north polar deposits: stratigraphy, age, and geodynamical response.  

PubMed

The Shallow Radar (SHARAD) on the Mars Reconnaissance Orbiter has imaged the internal stratigraphy of the north polar layered deposits of Mars. Radar reflections within the deposits reveal a laterally continuous deposition of layers, which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice. The packet/interpacket structure can be explained by approximately million-year periodicities in Mars' obliquity or orbital eccentricity. The observed approximately 100-meter maximum deflection of the underlying substrate in response to the ice load implies that the present-day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers. Alternatively, the response to the load may be in a transient state controlled by mantle viscosity. Both scenarios probably require that Mars has a subchondritic abundance of heat-producing elements. PMID:18483402

Phillips, Roger J; Zuber, Maria T; Smrekar, Suzanne E; Mellon, Michael T; Head, James W; Tanaka, Kenneth L; Putzig, Nathaniel E; Milkovich, Sarah M; Campbell, Bruce A; Plaut, Jeffrey J; Safaeinili, Ali; Seu, Roberto; Biccari, Daniela; Carter, Lynn M; Picardi, Giovanni; Orosei, Roberto; Mohit, P Surdas; Heggy, Essam; Zurek, Richard W; Egan, Anthony F; Giacomoni, Emanuele; Russo, Federica; Cutigni, Marco; Pettinelli, Elena; Holt, John W; Leuschen, Carl J; Marinangeli, Lucia

2008-05-30

40

Lunar impact basins: Stratigraphy, sequence and ages from superposed impact crater populations measured from Lunar Orbiter Laser Altimeter (LOLA) data  

E-print Network

Impact basin formation is a fundamental process in the evolution of the Moon and records the history of impactors in the early solar system. In order to assess the stratigraphy, sequence, and ages of impact basins and the ...

Fassett, C. I.

41

Identifying Fracture Types and Relative Ages Using Fluid Inclusion Stratigraphy  

SciTech Connect

Enhanced Geothermal Systems (EGS) are designed to recover heat from the subsurface by mechanically creating fractures in subsurface rocks. Understanding the life cycle of a fracture in a geothermal system is fundamental to the development of techniques for creating fractures. Recognizing the stage of a fracture, whether it is currently open and transmitting fluids; if it recently has closed; or if it is an ancient fracture would assist in targeting areas for further fracture stimulation. Identifying dense fracture areas as well as large open fractures from small fracture systems will also assist in fracture stimulation selection. Geothermal systems are constantly generating fractures, and fluids and gases passing through rocks in these systems leave small fluid and gas samples trapped in healed microfractures. Fluid inclusions trapped in minerals as the fractures heal are characteristic of the fluids that formed them, and this signature can be seen in fluid inclusion gas analysis. Our hypothesis is that fractures over their life cycle have different chemical signatures that we can see in fluid inclusion gas analysis and by using the new method of fluid inclusion stratigraphy (FIS) the different stages of fractures, along with an estimate of fracture size can be identified during the well drilling process. We have shown with this study that it is possible to identify fracture locations using FIS and that different fractures have different chemical signatures however that signature is somewhat dependent upon rock type. Open, active fractures correlate with increase concentrations of CO2, N2, Ar, and to a lesser extent H2O. These fractures would be targets for further enhancement. The usefulness of this method is that it is low cost alternative to current well logging techniques and can be done as a well is being drilled.

Dilley, Lorie M.; Norman, David; Owens, Lara

2008-06-30

42

Stratigraphy, sedimentology and diagenetic evolution of the Lapur Sandstone in northern Kenya: Implications for oil exploration of the Meso-Cenozoic Turkana depression  

NASA Astrophysics Data System (ADS)

The northern Turkana region of northwestern Kenya forms the intersection between two major rift systems in Africa, the Cretaceous-Paleogene Central African Rift System (CARS), and the eastern arm of the Paleogene-Present East African Rift System (EARS). The southern Sudanese oil-rich rift basins form part of the CARS, and their extension into the Anza Rift in northeastern Kenya makes the area of northern Turkana an important target for oil exploration. Limited past exploration activity in the area leaves the study of surface outcrops as the main avenue for understanding the reservoir potential of the fluvial deposits of these rift systems. The outcrops of these potential reservoirs, collectively referred to as "Turkana Grits" in the past, are represented on the western side of Lake Turkana by the Lapur Sandstone in the north, and by other grit formations in the central and southern parts of the basin. Isotopic age determinations on the basal parts of the "Turkana Volcanics" that overlie the Lapur Sandstone have enabled the precise dating of the upper parts of the LS at between 35 and 37 Ma, while the lower part of the formation near the contact with the underlying Precambrian basement is estimated as Upper Cretaceous (Turonian-early Campanian), based on the discovery of dinosaur and other reptilian fauna. Detailed lithological logging, coupled with subsequent petrographic and sedimentological studies, have enabled the determination of the depositional environments and the diagenetic evolution of the Lapur Sandstone. The basal and uppermost parts of the formation are interpreted as distal alluvial fan environments possibly connected to the last stages of rifting characterizing the Central African Rift System. The middle part of the Lapur Sandstone corresponds to a wide braided fluvial system that can be compared to fluvial episodes of Late Cretaceous age in the Sudan region, associated to major palaeogeographical changes in northern Africa. The nearly abrupt disappearance of the Lapur upper fan system relates to the deposition of the "Turkana Volcanics" from Late Eocene, possibly as a consequence of the emplacement of the Afar Plume at 45-35 Ma. In terms of diagenesis, the main cement material at the base of the Lapur Sandstone is calcite, whereas at the middle of the formation, hematite becomes the dominant cement, and at the topmost section, kaolin cement dominates. The diagenetic evolution of the sandstones has been favourable to the retention of adequate primary intergranular porosity and the creation of secondary intragranular dissolution porosity, mainly through feldspar dissolution, and thus preserving the reservoir potential of the Lapur Sandstone. The reservoir characteristics, such as the porosity and cementation style, of the Lapur Sandstone are comparable to those of the fluvial sandstone reservoirs of the southern Sudan oil fields and this should positively contribute to the overall petroleum potential of the northern Turkana region. Though the northern Turkana area has remained largely unexplored, it is hoped that the demonstration of the presence of reasonably good reservoir quality sandstones in the Lapur Sandstone will serve to encourage further interest in hydrocarbon exploration in the Turkana area.

Tiercelin, Jean-Jacques; Potdevin, Jean-Luc; Thuo, Peter Kinyua; Abdelfettah, Yassine; Schuster, Mathieu; Bourquin, Sylvie; Bellon, Hervé; Clément, Jean-Philippe; Guillou, Hervé; Nalpas, Thierry; Ruffet, Gilles

2012-08-01

43

Principles of lake sedimentology  

SciTech Connect

This book presents a comprehensive outline on the basic sedimentological principles for lakes, and focuses on environmental aspects and matters related to lake management and control-on lake ecology rather than lake geology. This is a guide for those who plan, perform and evaluate lake sedimentological investigations. Contents abridged: Lake types and sediment types. Sedimentation in lakes and water dynamics. Lake bottom dynamics. Sediment dynamics and sediment age. Sediments in aquatic pollution control programmes. Subject index.

Janasson, L.

1983-01-01

44

Edgar_Answers to student questions 414.pdf Student questions: Lauren Edgar colloquium on "Martian Sedimentology as Revealed by the  

E-print Network

Sedimentology as Revealed by the Curiosity Rover" 3/26/14 Question 1: How are the studies that you've done of the same kinds of instruments to investigate the sedimentology and stratigraphy at each landing site

Rhoads, James

45

BGS School of Field Geology An introduction to Sequence Stratigraphy  

E-print Network

Stratigraphy in the field.The course also provides the opportunity to gain experience of clastic sedimentology stratigraphic approaches to the division of rock successions, sedimentology of Cretaceous alluvial to marine siliciclastic rocks, sedimentology of Permian to Cretaceous alluvial, red bed successions, including palaeosols

46

Evaporite sedimentology  

SciTech Connect

The purpose of this book is to introduce the sedimentology of evaporites and to demonstrate how sedimentological principles can be applied to ancient evaporites. It includes chapter on: Sabkhas; marine and continental; Shallow water evaporites: lakes, salinas and platforms; and deep water evaporites.

Warren, J.K.

1989-01-01

47

Reservoir sedimentology  

SciTech Connect

Collection of papers focuses on sedimentology of siliclastic sandstone and carbonate reservoirs. Shows how detailed sedimentologic descriptions, when combined with engineering and other subsurface geologic techniques, yield reservoir models useful for reservoir management during field development and secondary and tertiary EOR. Sections cover marine sandstone and carbonate reservoirs; shoreline, deltaic, and fluvial reservoirs; and eolian reservoirs. References follow each paper.

Tillman, R.W.; Weber, K.J.

1987-01-01

48

Implications for the early shield-stage evolution of Tenerife from K\\/Ar ages and magnetic stratigraphy  

Microsoft Academic Search

The combined use of field geology, radioisotopic dating and magnetic stratigraphy applied to the old shield volcanoes of Tenerife provides a reliable time framework for the early, shield-stage evolution of the island. The greater part of this new set of ages, obtained from sequences of lava flows is in agreement with the astronomical polarity time scale. This approach illustrates that

Hervé Guillou; Juan Carlos Carracedo; Raphael Paris; Francisco José Pérèz Torrado

2004-01-01

49

Sedimentology and Sequence Stratigraphy of the Lower Cretaceous Fortress Mountain and Torok Formations Exposed Along the Siksikpuk River, North-Central Alaska  

USGS Publications Warehouse

An exposure of the Lower Cretaceous Fortress Mountain and Torok Formations along the Siksikpuk River in north-central Alaska provides a rare opportunity to observe the stratigraphic contact between these two formations and to interpret the depositional facies and sequence stratigraphy of the exposed strata. The Fortress Mountain Formation at the base of the measured section includes braided-fluvial and coastal-plain facies deposited in a lowstand-systems tract, and an overlying succession of mostly shallow marine facies deposited in the basal part of a transgressive-systems tract. The overlying Torok Formation includes a thick, upward-deepening succession of marine-shelf to marine-slope facies deposited in the upper part of the transgressive-systems tract. The upper part of the section includes marine-slope and incised-slope-channel turbidite deposits of the Torok Formation, interpreted as a highstand-systems tract. Consideration of the balance between accommodation and sediment flux inferred from the sequence-stratigraphic analysis suggests that both tectonics and eustasy may have influenced deposition of the lowstand-systems and transgressive-systems tracts. In contrast, the highstand-systems tract may have been primarily influenced by progradation of a regional sediment-dispersal system and by subsidence induced by sediment loading.

Houseknecht, David W.; Schenk, Christopher J.; Wartes, Marwan A.

2007-01-01

50

Stratigraphy and age of the Cappadocia ignimbrites, Turkey: reconciling field constraints with paleontologic,  

E-print Network

with paleontologic, radiochronologic, geochemical and paleomagnetic data J.-L. Le Penneca, , A. Temelb , J Valibaba Tepe ignimbrite. Keywords: ignimbrite; geochronology; paleontology; stratigraphy; rock magnetism

51

sup 40 Ar\\/ sup 39 Ar age calibration of the litho- and paleomagnetic stratigraphies of the Ngorora Formation, Kenya  

Microsoft Academic Search

Precise eruptive ages have been determined by the laser-fusion, single-crystal ⁴°Ar\\/³⁹Ar method for juvenile volcanic feldspars from reworked and contaminated volcaniclastic rocks of the middle Miocene Ngorora Formation, Kenya Rift Valley. These ages range from 13.06 Ma at the base to 10.51 Ma toward the top of the type section near Kabarsero. Correlation of the local paleomagnetic stratigraphies with the

A. Deino; R. Drake; L. Tauxe; M. Monaghan

1990-01-01

52

A re-evaluation of the stratigraphy and sedimentology of the Day Point Formation (Chazy Group): A new look at old reefs  

SciTech Connect

The Day Point Formation (Chazy Group, Middle Ordovician) outcrops in the Champlain Valley of New York and Vermont. The stratigraphy of the Day Point Formation is complex, containing lithologic sequences that are unique at different localities around the Champlain Valley. The formation exhibits complex lateral interfingering of seven lithofacies: (1) Highly bioturbated sandstone with symmetrical and bifurcating ripples. (2) Bioturbated, brachiopod rich, wackestone facies. (3) Planar cross-bedded, interlayered sand and sandy packstone. (4) Interlayered sand and shale grading into sand and limestone layers. (5) Grainstone which, at some localities, contains mound-shaped bryozoan reefs, at other localities thin non-reefal sheet-like layers are present. The grainstone also has planar laminated and cross stratified beds. (6) Fine-grained, calcareous sandstone with planar and herringbone cross bedding, which in places contains small bryozoan reefs and thin sheet-reefs. (7) Planar cross bedded packstone containing bryozoan reefs and thin sheet-like non-reefal layers. The thin reefal layers are found where the mound-shaped reefs are absent. The sand units are found only in the lower portion of the Day Point Formation. The bryozoan reefs and non-reefal layers are associated with the sand beds in the lower portion of the Day Point Formation, and either live within the sand or on top of it. The bryozoans that form the non-reefal layers, found in the limestones, are contained within thin layers of sand. In contrast, no sand is found in the upper section of the Day Point Formation, yet the bryozoan reefs flourish.

Falkenberg, J.; Mehrtens, C.J. (Vermont Univ., Burlington, VT (United States). Dept. of Geology)

1993-03-01

53

STRATIGRAPHY OF COUNTER-POINT-BAR AND EDDY-ACCRETION DEPOSITS IN LOW-ENERGY MEANDER BELTS OF THE PEACE-ATHABASCA  

E-print Network

Sedimentologic Solutions, 2104 3rd Avenue NW, Calgary, AB, T2N 0K4, Canada DALE A. LECKIE, AND MILOVAN FUSTIC 801 little research attention, and their stratigraphy and sedimentology is poorly understood in modern-point-bar deposits (CPBD) (Smith et al., 2009). Smith et al. (2009) examined the stratigraphy, sedimentology

54

AGE AND ORIGIN OF THE CHICXULUB IMPACTAND SANDSTONE COMPLEX, BRAZOS RIVER, TEXAS: EVIDENCE FROM LITHOSTRATIGRAPHY AND  

E-print Network

LITHOSTRATIGRAPHY AND SEDIMENTOLOGY THIERRY ADATTE Geological and Paleontological Institute, Anthropole, CH-1015 on the lithology, sedimentology, mineralogy, and biostratigraphy of upper Maastrichtian to lower Danian boundary, sedimentology, sequence stratigraphy, mineralogy, organic matter, sea level, depositional environment, incised

Keller, Gerta

55

Analytical sedimentology  

SciTech Connect

Both a self instruction manual and a cookbook'' guide to field and laboratory analytical procedures, this book provides an essential reference for non-specialists. With a minimum of mathematics and virtually no theory, it introduces practitioners to easy, inexpensive options for sample collection and preparation, data acquisition, analytic protocols, result interpretation and verification techniques. This step-by-step guide considers the advantages and limitations of different procedures, discusses safety and troubleshooting, and explains support skills like mapping, photography and report writing. It also offers managers, off-site engineers and others using sediments data a quick course in commissioning studies and making the most of the reports. This manual will answer the growing needs of practitioners in the field, either alone or accompanied by Practical Sedimentology, which surveys the science of sedimentology and provides a basic overview of the principles behind the applications.

Lewis, D.W. (Univ. of Canterbury, Christchurch (New Zealand). Dept. of Geology); McConchie, D.M. (Southern Cross Univ., New South Wales (Australia). Centre for Coastal Management)

1994-01-01

56

Initial insights from the Baumkirchen Palaeo-lake Record: Sedimentology, Stratigraphy and Geochemistry of a unique Marine Isotope Stage 3 succession in the Alps  

NASA Astrophysics Data System (ADS)

We present preliminary results from a 150 m-long core through a lacustrine sediment sequence from the Lower Inn Valley in the Eastern Alps. The banded clay sequence of Baumkirchen is the longest (over 220 m) known continuous pre-LGM sediment sequence in the Alps. Radiocarbon dates of wood from the upper section place the sequence in Marine Isotope Stage 3. Therefore the sequence provides a unique opportunity to study the climatic and ecological impacts of Greenland/North Atlantic Dansgaard Oeschger events (high frequency-high amplitude climate fluctuations) on the European Alps in high resolution. Millimetre and micrometre-scale X-ray fluorescence records, X-ray diffraction data, thin-section analysis and visual inspection reveal complexly laminated (mm-cm) sediments mainly of silt grain size, rich in mica with occasional coarse silty to fine sandy turbidites (mm to >10 cm thick). X-ray diffraction in conjunction with X-ray fluorescence reveal high-amplitude variations in both dolomite (dominant) and calcite suggesting a clastic origin of the laminae. No evidence of authigenic calcite forming biogenic varves was found. Rare, short sections (up to 0.5 m) are unlaminated, and along with variations in lamina thickness and frequency of turbidites, show changing sedimentary conditions, giving a relative and qualitative record of environmental and climatic change through the lake's history. Future work will focus on quantitative proxies (e.g. pollen and biomarkers) and establish an age model using optically stimulated luminescence dating. A further coring campaign (summer 2013) will increase the length of the core to cover the entire lacustrine section, possibly covering the entire Marine Isotope Stage 3.

Barrett, Samuel; Spötl, Christoph; Brauer, Achim; Dulski, Peter

2013-04-01

57

Kandik basin stratigraphy, sedimentology, and structure  

SciTech Connect

East-central Alaska's Kandik basin is a structural remnant of a larger Permian to Cretaceous basin. Permian shallow-water Tahkandit Limestone and Step Conglomerate at the base of the sequence rest unconformably on Paleozoic chert-pebble conglomerate, siliceous shale, and limestone. These Permian rocks are overlain by Triassic to Lower Cretaceous open-ocean Glenn Shale, which grades upward into Lower Cretaceous (Valanginian) hummocky cross-bedded (outer shelf to upper slope) Keenan Quartzite. The quartzite grades upward into fine-grained north-northeast-flowing turbidites of the Biederman Argillite (undated). East-northeast-flowing pebbly turbidites of the Kathul Graywacke (undated) overlie Biederman strata. Locally, Cretaceous (Albian and younger) through Paleogene nonmarine rocks unconformably overlie the Kandik basin sequence. The Mesozoic part of the sequence is similar to that of Manley basin, northwest Yukon Territory, and much of the North Slope. East-directed flow for Kandik basin strata may require paleogeographic reconstructions involving local to large-scale palinspastic rotations or a western source of chert detritus. Deformation of the Mesozoic sequence in Kandik basin west of the US-Canada border shows northwest-southeast shortening. Shaly units are tightly folded with well-developed cleavage striking northeast. Strikes of beds swing from northeast to east in the extreme southwestern part of the basin, suggesting clockwise rotation. Thrust faults, reverse faults, and fold axes trend east to northeast; normal faults trend northwest. These relations are all consistent with, and probably are closely related to, right slip on the west-northwest-trending Tintina fault.

Wiley, T.J.; Howell, D.G.; Kauffman-Linam, L.; Boundy-Sanders, S.; Murray, R.W.; Jones, D.L.

1987-05-01

58

Mars Stratigraphy Mission  

NASA Technical Reports Server (NTRS)

The Mars Stratigraphy Mission lands a rover on the surface of Mars which descends down a cliff in Valles Marineris to study the stratigraphy. The rover carries a unique complement of instruments to analyze and age-date materials encountered during descent past 2 km of strata. The science objective for the Mars Stratigraphy Mission is to identify the geologic history of the layered deposits in the Valles Marineris region of Mars. This includes constraining the time interval for formation of these deposits by measuring the ages of various layers and determining the origin of the deposits (volcanic or sedimentary) by measuring their composition and imaging their morphology.

Budney, C. J.; Miller, S. L.; Cutts, J. A.

2000-01-01

59

Ninth international congress on Carboniferous stratigraphy and geology. Proceedings, volume 3. Neuvieme congres international de stratigraphie et de geologie du Carbonifere. Compte rendu, volume 3  

SciTech Connect

Papers were presented on the Carboniferous stratigraphy of the Atlantic Coast basins, on paleogeography and paleotectonics and on sedimentology and geochemistry. A total of 14 papers concerning coal have been abstracted separately. Papers are in English or in French.

Geldsetzer, H.H.J.; Nassichuk, W.W.; Belt, E.S.; Macqueen, R.W.

1984-01-01

60

Stratigraphy and Magnetostratigraphic\\/Faunal Constraints for the Age of Sauropod Embryo-Bearing Rocks in the Neuquén Group (Late Cretaceous, Neuquén Province, Argentina)  

Microsoft Academic Search

The stratigraphy and age of a sauropod nesting ground containing the first definitive em- bryonic remains of sauropods preserved inside their eggs is analyzed. The fossil locality, called Auca Mahuevo, occurs in the Anacleto Member of the Rio Colorado Formation in Neuquen Province, Argentina. The 5 m thick interval of overbank mudstones containing the fossilized eggs and embryos occurs near

LOWELL DINGUS; JULIA CLARKE; GARY R. SCOTT; CARL C. SWISHER; LUIS M. CHIAPPE; RODOLFO A. CORIA

2000-01-01

61

Cambrian Stratigraphy  

NSDL National Science Digital Library

This site describes in detail the stratigraphy of the Cambrian period, starting approximately 545 million years ago and ending about 490 million years ago. It was one of the most important and dramatic periods because the lower boundary of the Cambrian is not only the beginning of a new system, but also the start of the Paleozoic and the Phanerozoic. Also the Early Cambrian saw the extremely rapid diversification of multicellular animals, the Cambrian Explosion, which determined the animal evolution and is indirectly responsible for present-day life. The site defines both the bottom and the top of the Cambrian layers and also provides a list of type sections with corresponding dates. Two charts are provided. One shows the changes in age assignments from 1982 to 1998 and another shows a time line for the Vendian and the Cambrian. The site also includes a section on isotopic studies and paleomagnetism of Cambrian strata.

62

sup 40 Ar/ sup 39 Ar age calibration of the litho- and paleomagnetic stratigraphies of the Ngorora Formation, Kenya  

SciTech Connect

Precise eruptive ages have been determined by the laser-fusion, single-crystal {sup 40}Ar/{sup 39}Ar method for juvenile volcanic feldspars from reworked and contaminated volcaniclastic rocks of the middle Miocene Ngorora Formation, Kenya Rift Valley. These ages range from 13.06 Ma at the base to 10.51 Ma toward the top of the type section near Kabarsero. Correlation of the local paleomagnetic stratigraphies with the geomagnetic reversal time scale yields magnetochronologic age estimates that are younger than the isotopic ages by an average of 0.18 Ma. Much of the discrepancy can be eliminated if an inferred change in sea-floor spreading rate occurred at 13 Ma or earlier, rather than at 10.42 Ma as previously suggested. Sedimentation rates at Kabarsero calculated from the {sup 40}Ar/{sup 39}Ar results decrease from initial values of {approximately}25 cm/1,000 yr to {approximately}5 cm/1,000 yr toward the top of the section. The initial rapid sedimentation rates characterize the first 0.1 to 0.3 m.y. following emplacement of the underlying, voluminous, basin-filling Tiim Phonolites, indicating that the Baringo Basin at this time may not have existed as a rift valley created by extensional tectonics, but instead may have been a subsidence feature formed in response to removal of large volumes of magma from the lithosphere. A premolar tentatively identified as Proconsul sp. indet. found in the Ngorora Formation near the village of Bartabwa has been dated at {approximately}12.42 Ma, representing perhaps the last known occurrence of this genus in the fossil record.

Deino, A.; Drake, R. (Institute of Human Origins, Berkeley, CA (USA)); Tauxe, L. (Scripps Institute of Oceanography, La Jolla, CA (USA)); Monaghan, M. (Univ. of Chicago, IL (USA))

1990-07-01

63

Ochoan (upper Permian) stratigraphy and age determinations, southeastern New Mexico and west Texas  

SciTech Connect

Upper Permian strata, which are the stratotype of the Ochoan State (Series), have an extensive subsurface distribution and limited outcrop area in southeastern New Mexico and west Texas. The oldest strata are alternating laminae of anhydrite and calcite of the Castile Formation and are as much as 700 m thick. The closely related and overlying Salado Formation is a much as 600 m thick and is mostly halite and argillaceous halite with minor anhydrite. The overlying Rustler Formation is as much as 150 m thick and consists of anhydrite, red silty shale and magnesian limestone. Overlying red beds are the Quartermaster Formation (Dewey Lake Formation is a synonym, as is the term Pierce Canyon red beds), which is as much as 106 m thick and consist of fine sandstones, siltstones, and minor gypsum. The Castile rests disconformably on the Capitanian (middle Permian) Lamar Limestone Member of the Bell Canyon Formation and its equivalent, the Tansill Formation of the Artesia Group. Counting of Castile-Salado laminae and their posited relationship to astronomical cycles suggests that Castile-Salado deposition took only 200,000-300,000 yr. Limited assemblages of brachiopods and conodonts from the Rustler Formation indicate a Late Permian age, but are no more precise age indicators. A small assemblage of bivalves, K-Ar ages and magnetostratigraphy indicate a late Permian age for the Quartermaster Formation. There is no evidence to support a Triassic age assignment for the Quarter-master; it is disconformably overlain by the Upper Triassic (Carnian) Chinle group. Most workers us the Ochoan as a Late Permian Stage-Age, although its typical strata generally lack good age indicators and may represent relatively short and sporadic intervals of the Late Permian. We prefer recognition of the Ochoan as a lithostratigraphic unit (group) without regional or global geochronologial significance.

Lucas, S.G. (New Mexico Museum of Natural History, Albuquerque, NM (United States)); Anderson, O.R. (New Mexico Bureau of Mines Mineral Resources, Socorro, NM (United States))

1994-03-01

64

Sedimentology, weathering, age and geomorphological significance of Tertiary sediments on the far south coast of New South Wales  

Microsoft Academic Search

The age of the NSW coastal lowland from Tuross to the Victorian border can now be shown to be at least mid?Tertiary. By this time the coastal plain had twice been partially blanketed by terrestrial sediments. Palaeomagnetic determinations on the more recent of these sedimentary accumulations, the Long Beach Formation, reveal a minimum depositional age of Early Miocene. Eustatic influences

J. F. Nott; R. W. Young; M. Idnurm

1991-01-01

65

Nonmarine stratigraphy of latest Cretaceous and early Tertiary age, southwestern New Mexico  

SciTech Connect

Recent fossil collections from nonmarine strata at localities in southwestern New Mexico indicate that the Ringbone formation, as originally defined, comprises units separated by a major hiatus that is represented in the field by an angular unconformity. The lower unit has yielded (NMMNH locality 298) two anterior caudal vertebral centra, morphologically and metrically indistinguishable from those of the Late Cretaceous tyrannosaurids Albertosaurus and Daspletosaurus. These dinosaur fossils establish a late Campanian or Maastrichtian age for the unit, indicating its equivalence with the McRae Formation of south-central New Mexico and the Fort Crittenden Formation of southeastern Arizona. The unit is composed of approximately 1,000 m of sedimentary-clast conglomerate, arkose, volcanic litharenite, and gray shale; it thus appears to contain detritus from several different source areas. The younger unit has yielded a low-diversity ostracod fauna of Paleocene to early Eocene age. Diagnostic taxa from the assemblage include Pseudoeocypris pagei and Cypridea arvadensis. The age of this fauna suggests equivalence with the Love Ranch and Lobo Formations of southern New Mexico. The unit consists of approximately 350 m of interbedded red siltstone and boulder conglomerate derived from Lower Cretaceous strata overlain by a sequence of laminated shale and subordinate sandstone with a preserved thickness of 150 m.

Lawton, T.F.; Mack, G.H.; Lucas, S.G.; Kietzke, K.K. (New Mexico State Univ., Las Cruces (USA))

1989-09-01

66

Age, Stratigraphy, and Correlations of the Late Neogene Purisima Formation, Central California Coast Ranges  

USGS Publications Warehouse

The Purisima Formation is an important upper Miocene and Pliocene stratigraphic unit in central California, cropping out from the coast at Point Reyes north of San Francisco to more extensive exposures in the Santa Cruz Mountains to the south. The fine-grained rocks in the lower parts of the Purisima Formation record a latest Miocene transgressive event, whereas the middle and upper parts of the formation consist of increasingly clastic-rich siltstones and sandstones resulting from uplift of adjacent coastal regions and the Sierra Nevada during Pliocene transgressive and regressive sea-level events. Exposures of the Purisima occur in three different, fault-bounded, structural blocks - the Santa Cruz, Pigeon Point, and Point Reyes tectonic blocks - that complicate correlations and regional age assignments. We summarize and compare published and new biostratigraphic and geochronologic data for various exposures of the Purisima Formation on the basis of mollusks, diatoms, radiometric dating, magnetostratigraphy, tephrochronology, and strontium isotope dating. On the basis of these data, we conclude that the Purisima Formation ranges in age from the latest Miocene (about 7 Ma) to the late Pliocene (about 2.6 Ma). The Purisima Formation of Santa Cruz County, exposed in the sea cliffs from Santa Cruz to Rio del Mar, is here designated a supplementary reference section because it is the most complete and well studied Purisima section in central California.

Powell, Charles L.; Barron, John A.; Sarna-Wojcicki, Andrei M.; Clark, Joseph C.; Perry, Frank A.; Brabb, Earl E.; Fleck, Robert J.

2007-01-01

67

Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: new constraints from laminae analysis and radiocarbon age modeling  

USGS Publications Warehouse

The Lake Bosumtwi sediment record represents one of the longest and highest-resolution terrestrial records of paleoclimate change available from sub-Saharan Africa. Here we report a new sediment age model framework for the last ~ 45 cal kyr of sedimentation using a combination of high-resolution radiocarbon dating, Bayesian age-depth modeling and lamination counting. Our results highlight the practical limits of these methods for reducing age model uncertainties and suggest that even with very high sampling densities, radiocarbon uncertainties of at least a few hundred years are unavoidable. Age model uncertainties are smallest during the Holocene (205 yr) and the glacial (360 yr) but are large at the base of the record (1660 yr), due to a combination of decreasing sample density, larger calibration uncertainties and increases in radiocarbon age scatter. For portions of the chronology older than ~ 35 cal kyr, additional considerations, such as the use of a low-blank graphitization system and more rigorous sample pretreatment were necessary to generate a reliable age depth model because of the incorporation of small amounts of younger carbon. A comparison of radiocarbon age model results and lamination counts over the time interval ~ 15–30 cal kyr agree with an overall discrepancy of ~ 10% and display similar changes in sedimentation rate, supporting the annual nature of sediment laminations in the early part of the record. Changes in sedimentation rates reconstructed from the age-depth model indicate that intervals of enhanced sediment delivery occurred at 16–19, 24 and 29–31 cal kyr, broadly synchronous with reconstructed drought episodes elsewhere in northern West Africa and potentially, with changes in Atlantic meridional heat transport during North Atlantic Heinrich events. These data suggest that millennial-scale drought events in the West African monsoon region were latitudinally extensive, reaching within several hundred kilometers of the Guinea coast. This is inconsistent with a simple southward shift in the mean position of the monsoon rainbelt, and requires changes in moisture convergence as a result of either a reduction in the moisture content of the tropical rainbelt, decreased convection, or both.

Shanahan, Timothy M.; Beck, J. Warren; Overpeck, Jonathan T.; McKay, Nicholas P.; Pigati, Jeffrey S.; Peck, John A.; Scholz, Christopher A.; Heil, Clifford W., Jr.; King, John W.

2012-01-01

68

Subsurface stratigraphy and geochemistry of late Quaternary evaporites, Searles Lake, California, with a section on radiocarbon ages of stratigraphic units  

USGS Publications Warehouse

Searles Lake is a dry salt pan, about 100 km 2 in area, that lies on the floor of Searles Valley, in the desert of southeast California. Several salt bodies of late Quaternary age lie beneath the surface, mostly composed of sodium and potassium carbonate, sulfate, chloride, and borate minerals. Mud layers separate the salt bodies, which contain interstitial brine that is the source of large quantities of industrial chemicals. The value of annual production from the deposit exceeds $30 million; total production to date exceeds $1 billion. The salts and muds were deposited during Pleistocene and Holocene times by a series of large lakes (200 m maximum depth, 1,000 km 2 maximum area) that fluctuated in size in response to climatic change. Salts were deposited during major dry (interpluvial) episodes, muds during wet (pluvial) episodes that correlate with glacial advances in other parts of North America and the world. Data based on cores from the deposit are used in this paper to establish the stratigraphy of the deposit, the chemical and mineral compositions of successive units, and the total quantities of components contained by them. These parameters are then used to determine the geochemical evolution of the sedimentary layers. The results provide a refined basis for reconstructing the limnology of Searles Lake and the regional climate during late Quaternary time. Six main stratigraphic units were distinguished and informally named earlier on the basis of their dominant composition: Unit Typical thickness 14C age, uncorrected (in meters) (years B.P.) Overburden Mud 7 0 to >3,500 Upper Salt 15 >3,500 to 10,500 Parting Mud 4 10,500 to 24,000 Lower Salt 12 24,000 to 32,500 Bottom Mud 30 32,500 to 130,000 Mixed Layer 200+ > 130,000 (The age of 130,000 years for the Mixed Layer is based on extrapolated sedimentation rates.) The Lower Salt is subdivided into seven salt units (S-l to S-7) and six mud units (M-2 to M-7), the Mixed Layer into six units (A to F). For each salt unit, the areal extent, volume, shape, mineralogy, and chemical composition of the solids and brines have been determined; for each mud unit (which originally extended over much of the basin), the shape and volume within a standard area, and the mineralogy, have been determined. The bulk compositions (brines plus salts) of the combined Lower Salt units S-l to S-5 and units S-6 and S-7, and the Upper Salt, were determined so that the total quantities and ratios of ions in the initial brines could be reconstructed. The 74 published HC dates on Searles Lake core samples from all but the oldest unit are supplemented by 14 new dates (determined by Minze Stuiver) on the Lower Salt. Most of the age control comes from dates based on disseminated organic carbon; two dates are on wood; dates on carbonate minerals are less reliable. Although the probable disequilibrium between the carbon in the lake and atmosphere (because of contamination, slow equilibrium rates, and other factors) causes disseminated carbon dates to be an estimated 500-2,500 years 'too old,' the ages of the major and minor units are relatively well established. The list above indicates rounded and uncorrected ages for the contacts of major units. The age of the only salt bed in the Lower Salt which indicates desiccation (S-5) is about 28,000 years. The average uncorrected sedimentation rate in the Parting Mud is 4

Smith, George I.; Stuiver, Minze

1979-01-01

69

Stratigraphy, age and environments of the late Miocene Mpesida Beds, Tugen Hills, Kenya.  

PubMed

Interpretations of faunal assemblages from the late Miocene Mpesida Beds in the Tugen Hills of the Central Kenyan Rift Valley have figured prominently in discussions of faunal turnover and establishment of the modern East African communities. These faunal changes have important implications for the divergence of the human lineage from the African apes ca. 8-5 Ma. While fossil material recovered from the Mpesida Beds has traditionally been analyzed collectively, accumulating evidence indicates that Mpesida facies span the 7-6 Ma interval and are scattered more than 25 km along the eastern flanks of the Tugen Hills. Stratigraphic distinctions between Mpesida facies and younger sediments in the sequence, such as the Lukeino Formation, are not yet fully resolved, further complicating temporal assessments and stratigraphic context of Mpesida facies. These issues are discussed with specific reference to exposures of Mpesida facies at Rurmoch, where large fossil tree fragments were swept up in an ancient ash flow. Preserved anatomical features of the fossil wood as well as estimated tree heights suggest a wet, lowland rainforest in this portion of the rift valley. Stable isotopic analyses of fossil enamel and paleosol components indicate the presence of more open habitats locally. Overlying air-fall tuffs and epiclastic debris, possibly associated with the ash flow, have yielded an assemblage of vertebrate fossils including two teeth belonging to one of the earliest colombines of typical body size known from Africa, after the rather small Microcolobus. Single-crystal, laser-fusion,(40)Ar/(39)Ar dates from a capping trachyte flow as well as tuffs just below the lava contact indicate an age of greater than 6.37 Ma for the fossil material. PMID:11795970

Kingston, John D; Fine Jacobs, Bonnie; Hill, Andrew; Deino, Alan

2002-01-01

70

Lithofacies, Age, and Sequence Stratigraphy of the Carboniferous Lisburne Group in the Skimo Creek Area, Central Brooks Range  

USGS Publications Warehouse

The Lisburne Group, a mainly Carboniferous carbonate succession that is widely distributed across northern Alaska, contains notable amounts of oil and gas at Prudhoe Bay. Detailed studies of the Lisburne in the Skimo Creek area, central Brooks Range, delineate its lithofacies, age, conodont biofacies, depositional environments, and sequence stratigraphy and provide new data on its hydrocarbon source-rock and reservoir potential, as well as its thermal history, in this area. We have studied the Lisburne Group in two thrust sheets of the Endicott Mountains allochthon, herein called the Skimo and Tiglukpuk thrust sheets. The southern, Skimo Creek section, which is >900 m thick, is composed largely of even-bedded to nodular lime mudstone and wackestone intercalated with intervals of thin- to thick-bedded bioclastic packstone and grainstone. Some parts of the section are partially to completely dolomitized and (or) replaced by chert. A distinctive, 30-m-thick zone of black, organic-rich shale, lime mudstone, and phosphorite is exposed 170 m below the top of the Lisburne. The uppermost 40 m of section is also distinctive and made up of dark shale, lime mudstone, spiculite, and glauconitic grainstone. The northern, Tiglukpuk Creek section, which is similar to the Skimo Creek section but only ~760 m thick, includes more packstone and grainstone and less organic-rich shale. Analyses of conodonts and foraminifers indicate that both sections range in age from late Early Mississippian (Osagean) through Early Pennsylvanian (early Morrowan) and document a hiatus of at least 15 m.y. at the contact between the Lisburne and the overlying Siksikpuk Formation. No evidence of subaerial exposure was observed along this contact, which may represent a submarine erosional surface. Lithofacies and biofacies imply that the Lisburne Group in the study area was deposited mainly in midramp to outer-ramp settings. Deepest water strata are mud rich and formed below storm or fair-weather wave base on the outer ramp to outer midramp; shallowest facies are storm, sand-wave, and shoal deposits of the inner midramp to inner ramp. A relatively diverse, open-marine fauna occurs throughout much of the Lisburne in the study area, but some beds also contain clasts typical of more restricted, shallow-water environments that were likely transported seaward by storms and currents. Radiolarians are abundant in the shale and phosphorite unit at Skimo Creek and also occur in equivalent strata at Tiglukpuk Creek; high gamma-ray response and elevated total organic-carbon contents (max 5?8 weight percent) also characterize this unit at Skimo Creek. Lithologic, faunal, and geochemical data all suggest that these rocks formed mainly in an outer-ramp to basinal setting with low sedimentation rates, high productivity, and poorly oxygenated bottom water. Shale and mudstone at the top of the Lisburne Group accumulated in a similarly sediment starved, mainly outer ramp environment but lack comparable evidence for high nutrient and low oxygen levels during deposition. Vertical shifts in rock types and faunas delineate numerous parasequences and six probable third-order sequences in the study area; the same sequences are also recognized in the Lisburne Group to the east. Transgressive-system tracts in these sequences generally fine upward, whereas highstand-system tracts coarsen upward. Sequences in the Tiglukpuk Creek section are mostly thinner, contain thinner and more numerous parasequences, and accumulated in somewhat shallower settings than those in the Skimo Creek section. These differences reflect the more seaward position and, thus, increased accommodation space of the Skimo Creek section relative to the Tiglukpuk Creek section during deposition. Organic-rich calcareous shale in the shale and phosphorite unit has a cumulative thickness of at least 15 m and a lateral extent of >50 km; this lithology is the best potential hydrocarbon source rock in the Lisburne Group

Dumoulin, Julie A.; Whalen, Michael T.; Harris, Anita G.

2008-01-01

71

Practical sedimentology, Second edition  

SciTech Connect

This book is for technical professionals in mineral exploration, environmental management, agriculture or forestry, this new edition takes an interdisciplinary approach to provide a lively and detailed overview of practical sedimentology. Emphasizing application over theory, the text is streamlined for comprehension, and it features many summary tables and graphs. The ideal companion to Analytical Sedimentology, this volume updates both methodology and applications, incorporates software information and extensively covers new technical developments. Specifically designed for students and cross-functional practitioners, it requires minimal geological background.

Lewis, D.W. (Univ. of Canterbury, Christchurch (New Zealand). Dept. of Geology); McConchie, D.M. (Southern Cross Univ., New South Wales (Australia). Centre for Coastal Management)

1994-01-01

72

First Clarkforkian Equivalent Land Mammal Age in the Latest Paleocene Basal Sparnacian Facies of Europe: Fauna, Flora, Paleoenvironment and (Bio)stratigraphy  

PubMed Central

The Paleocene-Eocene Thermal Maximum (PETM) is correlated with the first occurrences of earliest modern mammals in the Northern Hemisphere. The latest Paleocene Clarkforkian North American Land Mammal Age, that has yielded rodents and carnivorans, is the only exception to this rule. However, until now no pre-PETM localities have yielded modern mammals in Europe or Asia. We report the first Clarkforkian equivalent Land Mammal Age in the latest Paleocene deposits of the basal Sparnacian facies at Rivecourt, in the north-central part of the Paris Basin. The new terrestrial vertebrate and macroflora assemblages are analyzed through a multidisciplinary study including sedimentologic, stratigraphic, isotopic, and palynological aspects in order to reconstruct the paleoenvironment and to evaluate biochronologic and paleogeographic implications. The mammals are moderately diverse and not abundant, contrary to turtles and champsosaurs. The macroflora is exceptional in preservation and diversity with numerous angiosperms represented by flowers, fruits, seeds and wood preserved as lignite material, revealing an abundance of Arecaceae, Betulaceae, Icacinaceae, Menispermaceae, Vitaceae and probably Cornaceae. Results indicate a Late Paleocene age based on carbon isotope data, palynology and vertebrate occurrences such as the choristoderan Champsosaurus, the arctocyonid Arctocyon, and the plesiadapid Plesiadapis tricuspidens. However, several mammal species compare better with the earliest Eocene. Among these, the particular louisinid Teilhardimys musculus, also recorded from the latest Paleocene of the Spanish Pyrenees, suggests a younger age than the typical MP6 reference level. Nevertheless, the most important aspect of the Rivecourt fauna is the presence of dental remains of a rodent and a “miacid” carnivoran, attesting to the presence of two modern mammalian orders in the latest Paleocene of Europe. Interestingly, these two groups are also the only modern groups recorded from the latest Paleocene of North America, making Rivecourt the first direct equivalent to the Clarkforkian Land Mammal Age outside of North America. PMID:24489703

Smith, Thierry; Quesnel, Florence; De Plöeg, Gaël; De Franceschi, Dario; Métais, Grégoire; De Bast, Eric; Solé, Floréal; Folie, Annelise; Boura, Anaïs; Claude, Julien; Dupuis, Christian; Gagnaison, Cyril; Iakovleva, Alina; Martin, Jeremy; Maubert, François; Prieur, Judicaël; Roche, Emile; Storme, Jean-Yves; Thomas, Romain; Tong, Haiyan; Yans, Johan; Buffetaut, Eric

2014-01-01

73

Recent Trends and Advances in Sedimentology.  

ERIC Educational Resources Information Center

Briefly surveys recent trends and developments in sedimentology. Includes Clastic sedimentary petrology, petrology of argillaceous rocks, terrigenous depositional environments, and chemical sedimentology. (MA)

Suttner, Lee J.

1979-01-01

74

Extended stratigraphy, palynology and depositional environments record the initiation of the Himalayan Gyirong Basin (Neogene China)  

E-print Network

Extended stratigraphy, palynology and depositional environments record the initiation Himalayas Neogene Sedimentology Palynology Climate change Tectonism a b s t r a c t Here we report new, paleo-current directions and provenance anal- ysis, together with palynological and paleontological data

Utrecht, Universiteit

75

Sedimentology and depositional environments of part of the Walden Creek Group, central east Tennessee  

SciTech Connect

Recent questions concerning the age of the Walden Creek Group (WCG), Ocoee Supergroup have increased interest in the depositional history of these rocks. This study focuses on the sedimentology and local stratigraphy of rocks in exposures of the lithologically diverse late Precambrian and/or lower Paleozoic WCG occurring within the Kinzel Springs and Wear Cove quadrangles. Units exposed in the structurally complex Alleghenian thrust setting include the Licklog, Shields, and Wilhite formations. These rocks are divided into twelve lithofacies composed of shale, siltstone, sandstone, conglomerate and carbonate rock. The lithofacies are grouped into seven facies associations indicating deposition below storm wave base in a deep-water, probably marine, environment. Within the study area, rocks of the Wilhite Formation represent deposition in basin plain, lower slope, slope, base of slope, and sandy channel environments. Rocks of the Shields Formation are coarse channel and related overbank deposits of the inner to middle parts of a deep water fan environment. The Licklog Formation contains rocks deposited as lobe and outer-fan or fan-fringe deposits in a middle- to lower-fan environment. These formations can be placed within a single depositional system composed of a submarine slope transitional with a basin plain, and of proximal channels and distal lobes in a sand-rich submarine fan system. Inferred depositional components (associations) compare well with general models of deep-water deposits associated with high gradient fan-delta-fed margins. The basin was bounded by an uplifted, most likely block faulted, margin composed of crystalline basement located to the northwest. Local sedimentologic and stratigraphic relationships suggest an overall progradational sequence during the deposition of these rocks.

Lewis, R.F. III (Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Geology and Geophysics); Miller, J.M.G. (Vanderbilt Univ., Nashville, TN (United States). Dept. of Geology)

1993-03-01

76

Stratigraphy, structure, absolute age, and paleontology of the upper Pleistocene deposits at Sankaty Head, Nantucket Island, Massachusetts  

USGS Publications Warehouse

The Sankaty Head cliff exposes drift of at least two glaciations and interglacial marine deposits. Radiocarbon, amino-acid- racemization, and uranium-thorium analyses were used to determine the absolute ages of the beds. The results indicate that 1) the Sankaty Sand correlates with oxygen-isotope stage 5 (Sangamonian), 2) the underlying drift is older than stage 5 (Illinoian or older) , and 3) the overlying drift is Wisconsinan in age. -from Authors

Oldale, Robert N.; Valentine, Page C.; Cronin, T. M.; Spiker, E. C.; Blackwelder, B. W.; Belknap, D.F.; Wehmiller, J. F.; Szabo, B. J.

1982-01-01

77

Stratigraphy, age and petrography of the Beni Issef successions (External Rif; Morocco): Insights for the evolution of the Maghrebian Chain  

NASA Astrophysics Data System (ADS)

In the Beni Issef Massif, nearly 30 km west of Chefchaouen (Morocco), the thickest post-nappe succession within the Rifian sector of the Maghrebian Chain seals the tectonic contact between the Intrarifian External Tanger and Loukkos Units, related to the Rifian External Domain. This succession is very important for the reconstruction of the deformation timing of the Rifian Maghrebids. The age of its base, in fact, is an important constraint for defining an upper boundary to the stacking of both the Intrarifian and Maghrebian Flysch Basin Units, because clasts fed by the Melloussa and Numidian Flysch Nappes are abundant in the conglomerate layers. Field and biostratigraphic analyses pointed out the presence of a Lower Beni Issef Fm, unconformable on the Intrarifian External Tanger and Loukkos Units, and an Upper Beni Issef Fm, unconformable on both the Intrarifian Units and the Lower Beni Issef Fm. The Lower Beni Issef Fm, 150 m thick, consists of lenticular conglomerates with huge blocks in a marly-clayey matrix, followed by marls and minor sandstones. It deposited in a siliciclastic platform, shows a fining upward trend and is affected by metre- to hectometre-sized, locally reversed, folds. Samples collected 45-50 m above the base of the formation resulted not older than Late Tortonian in age, but an older age for the base of the formation cannot be excluded. The Upper Beni Issef Fm, up to 550 m thick, starts with coarse conglomerates followed by medium- to coarse-grained well-bedded sandstones and by grey-blue marls and mudrocks. It indicates deposition in a channelized marine delta, with evolution towards pro-delta pelites, and shows sub-horizontal or gently dipping beds towards the east. Biostratigraphic data indicate a probable Messinian age for this formation. The composition of the arenites of both Lower Beni Issef and Upper Beni Issef Fms is quartzolithic and all samples show a notable content of monocrystalline well-rounded quartz and sedimentary lithic fragments. Detrital modes, all falling in the Quartzose Recycled and Transitional Recycled fields, suggest a provenance from recycling of sedimentary successions, easily recognizable in the Flysch Basin and External Units, mainly the Numidian Nappe sandstones. A Tortonian age of the Lower Beni Issef Fm would agree with the Late Serravallian age of the uppermost beds of the External Tanger Unit and indicate that the most probable age for the stacking of the Intrarifian Units falls in the Late Serravallian-Middle Tortonian time span. The Lower Beni Issef Fm was involved in a compressive tectonic phase testified by north-south striking folds. Later, probably during Messinian, the Upper Beni Issef Fm deposited in a younger intramontane basin, resting on both the Intrarifian Units and the Lower Beni Issef Fm. Successively, the Upper Beni Issef Fm was passively transported piggyback on top of the fold and thrust belt during later tectonic evolution of the Rifian Maghrebids. This tectonic evolution results quite similar to that recognized in the Tellian and Sicilian Maghrebids and also in the southern Apennines.

Di Staso, Angelida; Perrone, Vincenzo; Perrotta, Sonia; Zaghloul, Mohamed Najib; Durand-Delga, Michel

2010-09-01

78

The 1992 drill core from the Kalkkop impact crater, Eastern Cape Province, South Africa: stratigraphy, petrography, geochemistry and age  

NASA Astrophysics Data System (ADS)

New drill core data are provided which support earlier interpretations that the Kalkkop structure, a 600-630 m wide, near-circular feature south-southwest of Graaff-Reinet in the Eastern Cape Province of South Africa, is a meteorite impact crater. Shock metamorphosed clasts in suevitic crater fill and Re?Os isotope data of this breccia indicate the presence of a minor (0.05%) meteoritic component in the suevite. The new data come from a 1992 borehole, which transected the complete crater fill and extended from about 160 to 380 m depth into the sedimentary basement belonging to the Koonap Formation of the Beaufort Group (Karoo Supergroup). Dyke breccias were found in the otherwise coherent Beaufort Group sediments forming the floor to the Kalkkop Crater. Mostly narrow zones of different breccia types, including injections of lithic impact breccia, a possible pseudotachylite veinlet and cataclasite occur predominantly in an approximately 65 m wide zone below the crater floor, with a few other cataclasite occurrences found lower down in the basement. Stratigraphical crater constraints provide information for the depth-diameter scaling and breccia volumes associated with such small, bowl-shaped impact craters formed in sedimentary targets. U?Th series dating of limestone samples from near the top and the bottom of the crater sediment fill constraints the age of the Kalkkop impact event to about 250 ± 50 ka, similar to the age of the Pretoria Saltpan impact crater, also located in South Africa. The variety of different breccia types (polymict and monomict impact breccias; local formations of pseudotachylitic and cataclastic breccias) observed in the crater fill of the Kalkkop Crater indicates the need to carefully distinguish different breccia types in order to assess the respective importance of each formation.

Reimold, Wolf Uwe; Koeberl, Christian; Reddering, Jacobus S. V.

1998-05-01

79

Assistant or Associate Professor in Sedimentology  

E-print Network

Assistant or Associate Professor in Sedimentology The Department of Earth Sciences (DES), Mineral for a tenure-track Assistant or Associate Professor position in Sedimentology to begin in July 2015. We seek an innovative individual with excellent teaching and research skills in sedimentology. Expertise in Precambrian

80

Cretaceous Tethyan Stratigraphy  

NSDL National Science Digital Library

The objective of this site is to construct a database for Cretaceous Tethyan stratigraphy. Stratigraphic information, photos and charts are arranged by geologic stage in a vertical menu. The types of information found in this site include basin reference sections, basin or platform control sections, biostratigraphic and sequence stratigraphic data, as well as other data that support and refine correlations. Access to scientific forums about Tethyan stratigraphy and a list of relevant links are also provided.

Bruno, Granier

81

The USGS Bedform Sedimentology Site  

NSDL National Science Digital Library

The USGS Bedform Sedimentology Site offers materials that are companions to the book: Cross-Bedding, Bedforms, and Paleocurrents, by D. M. Rubin of the USGS Pacific Science Center. Visitors can read an online version of the book, read about bedform initiation, view QuickTime and MPEG movies of bedforms and cross-bedding, download bedform simulation software, and find out how to identify low-dimensional deterministic systems (chaos) in time series or spatial patterns.

1999-01-01

82

Workshop on the Martian Northern Plains: Sedimentological, Periglacial, and Paleoclimatic Evolution  

NASA Technical Reports Server (NTRS)

Papers that have been accepted for presentation at the Workshop on the Martian Northern Plains: Sedimentological, Periglacial, and Paleoclimatic Evolution, on 12-14 Aug. 1993 in Fairbanks, Alaska are included. Topics covered include: hydrological consequences of ponded water on Mars; morphological and morphometric studies of impact craters in the Northern Plains of Mars; a wet-geology and cold-climate Mars model: punctuation of a slow dynamics approach to equilibrium; the distribution of ground ice on Mars; and stratigraphy of the Martian Northern Plains.

Kargel, Jeffrey S. (editor); Moore, Jeffrey (editor); Parker, Timothy (editor)

1993-01-01

83

International Commission on Stratigraphy  

NSDL National Science Digital Library

This site provides information about the International Commission on Stratigraphy, a collection of downloadable stratigraphic charts and columns, an abridged version of the International Stratigraphic Guide, links to industry journals and publications, and links to a collection of other stratigraphy-related websites. It also features a detailed chart of global boundary stratotype sections and points, as well as the Time Scale Creator, software that lets users create customized downloadable charts of any portion of the geologic time scale and correlated earth history events. The site also links to the GeoWhen Database, a collection of detailed time-scale representations and classifications.

International Commission on Stratigraphy

84

USC Sequence Stratigraphy Web  

NSDL National Science Digital Library

Sequence stratigraphy is a technique used to subdivide the sedimentary section into packages that are defined by bounding unconformities and internal surfaces, and are the products of changes in relative sea level and rates of sedimentation. Sequence stratigraphic analyses are made from seismic cross-sections, well logs, and outcrop studies of sedimentary rocks to infer changes of relative sea level and rates of sedimentation, and predict the continuity and extent of their lithology. This University of South Carolina website provides: animated cartoons demonstrating how gross sedimentary geometric relationships develop in response to varying rates of change of sedimentation, eustasy, and tectonic movement; movies of sedimentary simulations; video narration; films on location; 3D perspectives; simple interactive exercises on chronostratigraphy; fact sheets on world petroleum; historical perspectives about stratigraphy; the potential to simulate the development of geometric relationships on-line; links; references; and on-line papers.

Kendall, Christopher

85

A luminescence dating study of the sediment stratigraphy of the Lajia Ruins in the upper Yellow River valley, China  

NASA Astrophysics Data System (ADS)

Pedo-sedimentological fieldwork were carried out in the Lajia Ruins within the Guanting Basin along the upper Yellow River valley. In the eolian loess-soil sections on the second river terrace in the Lajia Ruins, we find that the land of the Qijia Culture (4.20-3.95 ka BP) are fractured by several sets of earthquake fissures. A conglomerated red clay covers the ground of the Qijia Culture and also fills in the earthquake fissures. The clay was deposited by enormous mudflows in association with catastrophic earthquakes and rainstorms. The aim of this study is to provide a luminescence chronology of the sediment stratigraphy of the Lajia Ruins. Eight samples were taken from an eolian loess-soil section (Xialajia section) in the ruins for optically stimulated luminescence (OSL) dating. The OSL ages are in stratigraphic order and range from (31.94 ± 1.99) ka to (0.76 ± 0.02) ka. Combined OSL and 14C ages with additional stratigraphic correlations, a chronological framework is established. We conclude that: (1) the second terrace of the upper part of Yellow River formed 35.00 ka ago, which was followed by the accumulation of the eolian loess-soil section; and (2) the eolian loess-soil section is composed of the Malan Loess of the late last glacial (MIS-2) and Holocene loess-soil sequences.

Zhang, Yuzhu; Huang, Chun Chang; Pang, Jiangli; Zhou, Yali; Zha, Xiaochun; Wang, Longsheng; Zhou, Liang; Guo, Yongqiang; Wang, Leibin

2014-06-01

86

Stratigraphy of the Martian northern plains  

NASA Technical Reports Server (NTRS)

The northern plains of Mars are roughly defined as the large continuous region of lowlands that lies below Martian datum, plus higher areas within the region that were built up by volcanism, sedimentation, tectonism, and impacts. These northern lowlands span about 50 x 10(exp 6) km(sup 2) or 35 percent of the planet's surface. The age and origin of the lowlands continue to be debated by proponents of impact and tectonic explanations. Geologic mapping and topical studies indicate that volcanic, fluvial, and eolian deposition have played major roles in the infilling of this vast depression. Periglacial, glacial, fluvial, eolian, tectonic, and impact processes have locally modified the surface. Because of the northern plains' complex history of sedimentation and modification, much of their stratigraphy was obscured. Thus the stratigraphy developed is necessarily vague and provisional: it is based on various clues from within the lowlands as well as from highland areas within and bordering the plains. The results are summarized.

Tanaka, K. L.

1993-01-01

87

Long-Term Sedimentology Projects Using Local Geological and Environmental Problems  

NSDL National Science Digital Library

The goal of long-term laboratory projects is to allow students to apply newly learned concepts and methods to real-world problems and thereby add value to the laboratory learning experience. Effective projects are those that are carefully planned, have clearly defined learning objectives and reasonable workload and final product expectations. Exercises vary in length and content depending upon learning goals, class size, available resources, methodology and scheduling concerns (e.g. beginning or end of course, available class time or time of year). Each project begins with an introduction in which a geological question is posed and students are presented with background information, published reference material and guidelines for effective scientific writing. The introductory presentations are followed by group discussions to formulate the hypothesis(es) to be tested and determine the experimental design, with due consideration to the constraints listed above. It is important that students understand their individual responsibilities and their role in the larger group effort. In the following weeks, students are provided with the materials and methods they need to conduct each phase of the project. Students collect and process their own data whenever possible. Preferably this phase involves field description and collection of samples for later lab analysis but previously collected sediment or rock cores or samples may also be used. Data analysis is a class-wide effort with each student or student team contributing a component to a larger class-wide database. Workload expectations must be clearly defined and students must conform to a tight timeframe during the analysis portion of the exercise so that the final database is complete and available on schedule. Interim deadlines for data components generally help students stay on schedule during this phase. Data synthesis and final report preparation are individual efforts. Students are encouraged to be creative in the interpretation and presentation of their results but are warned not to draw conclusions that cannot be supported by their data. Examples of long-term projects that have been used for sedimentology at SUNY Plattsburgh include: Particle shape analysis of beach and fluvial gravel in the Champlain Valley Provenance of glacial till in the Champlain Valley and northeastern Adirondack Mountain region Sedimentology, stratigraphy and landslide susceptibility of proglacial lake and marine deposits on the Lake Champlain lakeshore in Plattsburgh, NY Sedimentology and stratigraphy of the Potsdam Sandstone in the Champlain Valley Sedimentological evidence for breakout floods in proglacial lake and marine deposits in the Champlain Valley

Franzi, David

88

Geomorphological and sedimentological record of accelerated deglaciation of small mountain glacier, Ragnarbreen, Svalbard  

Microsoft Academic Search

Most of the Svalbrad glaciers have been in retreat since the end of the Little Ice Age (LIA). Hence, they give a good opportunity to study the geomorphological and sedimentological record of deglaciation. The aim of the study is to describe main landsystem elements of Ragnar glacier and relate them to different stages of the glacier recession. The Ragnar glacier

Marek Ewertowski

2010-01-01

89

Continental margin sedimentation: from sediment transport to sequence stratigraphy  

USGS Publications Warehouse

This volume on continental margin sedimentation brings together an expert editorial and contributor team to create a state-of-the-art resource. Taking a global perspective, the book spans a range of timescales and content, ranging from how oceans transport particles, to how thick rock sequences are formed on continental margins. - Summarizes and integrates our understanding of sedimentary processes and strata associated with fluvial dispersal systems on continental shelves and slopes - Explores timescales ranging from particle transport at one extreme, to deep burial at the other - Insights are presented for margins in general, and with focus on a tectonically active margin (northern California) and a passive margin (New Jersey), enabling detailed examination of the intricate relationships between a wide suite of sedimentary processes and their preserved stratigraphy - Includes observational studies which document the processes and strata found on particular margins, in addition to numerical models and laboratory experimentation, which provide a quantitative basis for extrapolation in time and space of insights about continental-margin sedimentation - Provides a research resource for scientists studying modern and ancient margins, and an educational text for advanced students in sedimentology and stratigraphy

Nittrouer, Charles A., (Edited By); Austin, James A.; Field, Michael E.; Kravitz, Joseph H.; Syvitski, James P.M.; Wiberg, Patricia L.

2007-01-01

90

Proceedings, 1983 symposium on surface mining, hydrology, sedimentology, and reclamation  

SciTech Connect

Papers were presented on the following topics: mining technology; hydrology; sedimentology; reclamation; surface mining technology and policy; poster presentations; phosphate and arid land reclamation; reclamation special applications; and hydrology-sedimentology special applications. 45 papers have been abstracted separately.

Graves, D.H. (ed.)

1983-12-01

91

Geochemical and sedimentological investigations of Youngest Toba Tuff ashfall deposits  

E-print Network

sedimentological structures and geometry ...................................................... 90 5.5 Discussion .......................................................................................................................... 91 5.5.1 The local... ..................................................... 97 5.6 Conclusion ......................................................................................................................... 97 CHAPTER 6. DEPOSITIONAL PROCESSES AND SEDIMENTOLOGY OF YTT DEPOSITS IN THE LENGGONG VALLEY, MALAYSIA...

Gatti, Emma

2013-03-12

92

New high precision U-Pb ages for the Vinchina Formation: Implications for the stratigraphy of the Bermejo Andean foreland basin (La Rioja province, western Argentina)  

NASA Astrophysics Data System (ADS)

The Vinchina Formation is one of the thickest Cenozoic units related to the Andean orogeny in Argentina totaling more than 5100 m in thickness. Different ages, from Eocene to latest Miocene, have been postulated for this red-bed succession based on fission track, magnetostratigraphy and whole rock isotopic analyses. Two new high precision U-Pb zircon ages are reported herein for this unit. A maximum U-Pb age of 15.6 ± 0.4 Ma was obtained from detritic zircons collected from a thick tuffaceous interval of the Lower Member of the Vinchina Formation at La Cueva (Precordillera), while a depositional U-Pb age of 9.24 ± 0.034 Ma was derived from volcanic zircons collected from a thin tuff bed in the Upper Member at Quebrada de Los Pozuelos (Northwestern Sierras Pampeanas). At La Cueva, the Vinchina Formation unconformably overlies eolian sandstones of the Vallecito Formation and was divided into four units representing 1) deposits of high-sinuosity ephemeral rivers associated with 2) a playa-lake passing upwards to 3) low-sinuosity sandy ephemeral rivers and finally, 4) a gravelly-sandy braided plain. The tuffaceous level corresponding to unit 1 is located 280 m above the base of the formation. At Quebrada de Los Pozuelos, the Vinchina Formation unconformably overlies the Vallecito Formation and is covered by a deeply incised surface at the base of the Toro Negro Formation. We divided the Vinchina Formation into four units. Unit 1 represents sedimentation in shallow fluvial channels with sandy to muddy floodplains. Units 2 and 3 record sedimentation in braided, meandering and anastomosing rivers. Finally unit 4 represents deposition in braided and wandering fluvial systems. The sampled tuff is located within unit 4 at ?3470 m above the base of the formation. The new ages indicate that the bulk of the Vinchina Formation is Miocene in age but they do not preclude a longer time span for the sedimentation of the whole unit. Ages of the sampled volcanic zircons match an important episode of volcanism recorded in the Cerro Las Tórtolas Formation, located ?90 km to the west in the Andean Cordillera, but also the upper tuff could be related to the late Miocene Puna volcanism. Comparison of the new ages with previous chronological data suggests coetaneous sedimentation along different depocenters of the Bermejo basin (e.g., Vinchina and Talampaya depocenters in Western Sierras Pampeanas and La Troya depocenter and Huaco-Mogna sections in Precordillera) and strenghten the need for correlation among them. In addition the age of 15.6 ± 0.4 Ma constrains the end of the severe arid conditions recorded in the Sierras Pampeanas and Precordillera region.

Ciccioli, P. L.; Limarino, C. O.; Friedman, R.; Marenssi, S. A.

2014-12-01

93

Sedimentology of gas-bearing Devonian shales of the Appalachian Basin  

SciTech Connect

The Eastern Gas Shales Project (1976-1981) of the US DOE has generated a large amount of information on Devonian shale, especially in the western and central parts of the Appalachian Basin (Morgantown Energy Technology Center, 1980). This report summarizes this information, emphasizing the sedimentology of the shales and how it is related to gas, oil, and uranium. This information is reported in a series of statements each followed by a brief summary of supporting evidence or discussion and, where interpretations differ from our own, we include them. We believe this format is the most efficient way to learn about the gas-bearing Devonian shales of the Appalachian Basin and have organized our statements as follows: paleogeography and basin analysis; lithology and internal stratigraphy; paleontology; mineralogy, petrology, and chemistry; and gas, oil, and uranium.

Potter, P.E.; Maynard, J.B.; Pryor, W.A.

1981-01-01

94

Lithostratigraphy, petrography, biostratigraphy, and strontium-isotope stratigraphy of the surficial aquifer system of western Collier County, Florida  

USGS Publications Warehouse

In 1996, seven cores were recovered in western Collier County, southwestern Florida, to acquire subsurface geologic and hydrologic data to support ground-water modeling efforts. This report presents the lithostratigraphy, X-ray diffraction analyses, petrography, biostratigraphy, and strontium-isotope stratigraphy of these cores. The oldest unit encountered in the study cores is an unnamed formation that is late Miocene. At least four depositional sequences are present within this formation. Calculated age of the formation, based on strontium-isotope stratigraphy, ranges from 9.5 to 5.7 Ma (million years ago). An unconformity within this formation that represents a hiatus of at least 2 million years is indicated in the Old Pump Road core. In two cores, Collier-Seminole and Old Pump Road, the uppermost sediments of the unnamed formation are not dated by strontium isotopes, and, based on the fossils present, these sediments could be as young as Pliocene. In another core (Fakahatchee Strand-Ranger Station), the upper part of the unnamed formation is dated by mollusks as Pliocene. The Tamiami Formation overlies the unnamed formation throughout the study area and is represented by the Ochopee Limestone Member. The unit is Pliocene and probably includes the interval of time near the early/late Pliocene boundary. Strontium-isotope analysis indicates an early Pliocene age (calculated ages range from 5.1 to 3.5 Ma), but the margin of error includes the latest Miocene and the late Pliocene. The dinocyst assemblages in the Ochopee typically are not age-diagnostic, but, near the base of the unit in the Collier-Seminole, Jones Grade, and Fakahatchee Strand State Forest cores, they indicate an age of late Miocene or Pliocene. The molluscan assemblages indicate a Pliocene age for the Ochopee, and a distinctive assemblage of Carditimera arata and Chione cortinaria in several of the cores specifically indicates an age near the early/late Pliocene boundary. Undifferentiated sands overlie the Pliocene limestones in two cores in the southern part of the study area. Artificial fill occurs at the top of most of the cores. The hydrologic confining units penetrated by these cores are different in different parts of the study area. To the west, a hard tightly cemented dolostone forms the first major confining unit below the water table. In the eastern part of the study area, confinement is more difficult to determine. A tightly cemented sandstone, much younger than the dolostones to the west and probably not laterally connected to them, forms a slight confining unit in one core. Thick zones of poorly sorted muddy unconsolidated sands form a slight confining unit in other cores; these probably are not correlative to either the sandstone or the dolostones to the west. The age and sedimentologic observations suggest a complex compartmentalization of the surficial aquifer system in southwestern Florida. The calibrations of dinocyst and molluscan occurrences with strontium-isotope stratigraphy allows us to expand and document the reported ranges of many taxa. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Edwards, L.E.; Weedman, S.D.; Simmons, R.; Scott, T.M.; Brewster-Wingard, G. L.; Ishman, S.E.; Carlin, N.M.

1998-01-01

95

Sedimentology and sequence stratigraphy of the Lopingian (Late Permian) coal measures in southwestern China  

Microsoft Academic Search

The Lopingian coal measures of southwestern China were deposited within a range of facies associations spanning a spectrum of settings from fluvial to marine carbonate platform. The transitional to terrestrial coal measures are dominated by siliciclastics, but they also contain fifteen laterally extensive marine bands (limestone beds and mudstone). These bands act as marker horizons that enable correlation between fully

Hao Wang; Longyi Shao; Liming Hao; Pengfei Zhang; Ian J. Glasspool; James R. Wheeley; Paul B. Wignall; Tongsheng Yi; Mingquan Zhang; Jason Hilton

2011-01-01

96

Sedimentology and sequence stratigraphy of the Bryne and Lulu Formations, Middle Jurassic, northern Danish Central Graben  

Microsoft Academic Search

The Middle Jurassic Bryne and Lulu Formations of the Søgne Basin (northern part of the Danish Central Graben) consist of fluvially-dominated coastal plain deposits, overlain by interfingering shoreface and back-barrier deposits. Laterally continuous, mainly fining-upwards fluvial channel sandstones that locally show evidence for tidal influence dominate the alluvial\\/coastal plain deposits of the lower Bryne Formation. The sandstones are separated by

Jan Andsbjerg

2003-01-01

97

Stratigraphy, sedimentology, and petrology of Upper Cretaceous Horsethief and St. Mary River formations, western Montana  

Microsoft Academic Search

The Horsethief and St. Mary River formations were deposited along the Late Cretaceous epicontinental seaway, which then covered much of the western interior. The Horsethief, lower of the two formations, is divided into two facies sequences. Facies sequence A consist of coarsening-upward sequences of sandstones and interbedded shales. These facies comprise a barrier island system consisting of shoreface, dune, tidal

William Fairhurst

1983-01-01

98

Oligocene Hackberry Formation of southwest Louisiana: Sequence stratigraphy, sedimentology, and hydrocarbon potential  

Microsoft Academic Search

The Oligocene Hackberry sequence was deposited in a slope environment consisting of an irregular, updip slide scar, a rotational slide zone up to 4 mi (6.5 km) wide, and a downdip region more than 20 mi (32 km) wide where meandering submarine channels deposited thick turbiditic sands. The shelf margin slides probably began during the late stage of a relative

S. P. J. Cossey; R. E. Jacobs

1992-01-01

99

Sedimentology and Holocene stratigraphy of a carbonate mangrove buildup, Twin Cays, Belize, Central America  

E-print Network

. Halimeda is the dominant grain contributor from the lagoonal d' g yd. Ry d h p f Rhg h ~1 (red mangrove) is the major contributor in supratidal deposition. The surface sediments size distributions of the sediments are clearly related to present.... . . . . . . . . 39 45 46 An example of 0he size distribution of the surface sediments at Twin Cays. This is the distribution of medium sand sized grains. 15 North to south cross section drawn based upon descrip- tion of the sediment contained within the cores...

Bond, Gregor Benton

2012-06-07

100

Sedimentology, stratigraphy, and depositional environment of the Crystal Geyser Dinosaur Quarry, east-central Utah  

USGS Publications Warehouse

The Crystal Geyser Dinosaur Quarry, near Green River, Utah, is located at the base of the Lower Cretaceous (Barremian) Yellow Cat Member of the Cedar Mountain Formation. The quarry preserves a nearly monospecific accumulation of a new basal therizinosauroid, Falcarius utahensis. We used field descriptions and petrographic analysis to determine the depositional environment and development of the quarry strata. Results of these analyses suggest that the quarry represents multiple episodes of bone accumulation buried by spring and overbank flood deposits. Evidence for these previously undescribed spring deposits includes calcite macroscopic structures within the quarry strata - such as pisolites and travertine fragments - and calcite micromorphologies - including radial-fibrous, feather, and scandulitic dendrite morphologies and tufa clasts. At least two episodes of bone incorporation are preserved in the quarry based on their stratigraphic position and lithologic associations. The unique depositional setting in and around the Crystal Geyser Dinosaur Quarry appears to have been favorable for the preservation of vertebrate fossils and provides insight into early Cretaceous environments in North America. Copyright ?? 2007, SEPM (Society for Sedimentary Geology).

Suarez, M.B.; Suarez, C.A.; Kirkland, J.I.; Gonzalez, L.A.; Grandstaff, D.E.; Terry, D.O., Jr.

2007-01-01

101

Impact of sea level rise on the sedimentology and stratigraphy of estuarine systems  

SciTech Connect

Drowned-river valley estuaries are characteristic features of trailing-edge continental margins, as exemplified by the United States Atlantic Coast. During marine transgressions, the classic cycle of estuarine development is one of initial submergence and subsequent infilling, with the latter stages marked by extensive accumulations of fine-grained sediments in expanding marshes, deltas, and floodplains. Seismic surveys, vibracoring, and radiocarbon dating in the estuarine tributaries in middle Chesapeake Bay (The largest estuary along the Atlantic Coast), indicate that thick accumulations (>25 m) of organic-rich fine-grained sediments have been deposited since the middle Holocene. However, studies of recent accretion rate (based on pollen and radionuclide analyses) suggest the marshes, which represent a near-end member of the estuarine depositional sequence, may no longer be accumulating significant volumes of sediment. Relatively rapid crustal subsidence plus eustatic sea level rise produces a local submergence of approx. 4 mm/yr. Although marsh accretion rates in the upper estuarine tributaries approach 1 cm/yr, marsh accretion rates in the middle and lower reaches are significantly less (<2 mm/yr) than submergence. Here, numerous marshes are converting to open water as they become increasingly flooded by the tides. This change in depositional regime is also reflected in the carbon content (decreasing) and grain size (coarsening) of the marsh sediments and tidal channel migrations. In the coming decades, the rate of the world sea level rise is projected to increase significantly. This acceleration in the global eustatic trend together with lower sediment inputs from surrounding watersheds may reverse the historic trend of estuarine infilling.

Ward, R.F.; Kearney, M.S.

1988-01-01

102

Sedimentology of the Malawi Rift: Facies and stratigraphy of the Chiwondo Beds, northern Malawi  

Microsoft Academic Search

Shallow water, nearshore lake beds and fluviatile deposits exposed in the Karonga District (northern Malawi) are subdivided into several depositional units which are bounded by unconformities reflecting sedimentary breaks. Prior to the formation of a major perennial lake which also flooded the area studied, sedimentation was characterized by extensive fluviatile deposits mainly formed by reworked material of Jurassic red beds.

Christian Betzler; Uwe Ring

1995-01-01

103

Stratigraphy and sedimentology of a dry to wet eolian depositional system, Burns formation, Meridiani Planum, Mars  

Microsoft Academic Search

Outcrop exposures of sedimentary rocks at the Opportunity landing site (Meridiani Planum) form a set of genetically related strata defined here informally as the Burns formation. This formation can be subdivided into lower, middle, and upper units which, respectively, represent eolian dune, eolian sand sheet, and mixed eolian sand sheet and interdune facies associations. Collectively, these three units are at

J. P. Grotzinger; R. E. Arvidson; J. F. Bell III; W. Calvin; B. C. Clark; D. A. Fike; M. Golombek; R. Greeley; A. Haldemann; K. E. Herkenhoff; B. L. Jolliff; A. H. Knoll; M. Malin; S. M. McLennan; T. Parker; L. Soderblom; J. N. Sohl-Dickstein; S. W. Squyres; N. J. Tosca; W. A. Watters

2005-01-01

104

Sequence stratigraphy, sedimentology, and hydrocarbon potential in the North-Eastern part of the Pannonian Basin  

SciTech Connect

The Pannonian basin lies within the Alpine mountain belts of east-central Europe. Deformation of the Pannonian region occurred during the final stage of thrusting and folding in the outer part of the Carpathians. The result was a system of several smaller individual basins separated by relatively shallow basement blocks. The {open_quotes}North-eastern part of the Pannonian basin{close_quotes} represents one of these individual basins. Over the basement, the Neogene sedimentation started with continental or marine transgressive beds followed by shallow-marine shales and marls with sandy intercalations. Several stratigraphic sequences were separated within the succession of sedimentary deposits using the seismic, paleontologic, and well-log data. These sequences with their hydrocarbon significance are largely described in the paper.

Lazar, O.R.; Corbeanu, R.; Vasiliu, G. [Institute for Research and Technology, Prahova (Romania)] [and others

1995-08-01

105

Oligocene Hackberry Formation of southwest Louisiana: Sequence stratigraphy, sedimentology, and hydrocarbon potential  

SciTech Connect

The Oligocene Hackberry sequence was deposited in a slope environment consisting of an irregular, updip slide scar, a rotational slide zone up to 4 mi (6.5 km) wide, and a downdip region more than 20 mi (32 km) wide where meandering submarine channels deposited thick turbiditic sands. The shelf margin slides probably began during the late stage of a relative fall in sea level and prior to a maximum flood event in the middle Oligocene. The slides probably were caused by a combination of salt withdrawal and an unstable shelf edge. The play has produced more than 374 million bbl of oil equivalent (BOE) up to December 1988. The first fields were discovered in structural/stratigraphic traps on the updip flanks of the salt domes, where channels were forced to meander around paleobathymetric highs. Other fields are located in the paleobathymetric lows many miles downdip of the salt domes. Statistical analysis of field data shows that 41 fields with more than 1 million BOE each and with a total estimated ultimate recovery of 117 million BOE remain to be discovered in the play. Interpretation in southwestern Louisiana has shown that new reserves could be discovered in three potential reservoir sands: (1) lower Frio shelf-edge sands preserved in large slide blocks, (2) onlapping, sandy 'fill sequences' restricted to the lows between slide blocks, and (3) meandering, dip-oriented, sandy channel complexes less than 4,500 ft (1,400 m) wide. These three sandstones cannot be distinguished unless dipmeter, seismic, and paleontologic data are used in combination.

Cossey, S.P.J.; Jacobs, R.E. (BP Exploration, Houston, TX (United States))

1992-05-01

106

Neogene stratigraphy and sedimentology in eastern Azerbaijan: Outcrop observations and subsurface implications  

SciTech Connect

The largely Pliocene Productive Series of eastern Azerbaijan contains about 26 billion barrels oil equivalent. It is well exposed in outcrops on the Apsheron Peninsula which a joint team from the GIA and the BP and Statoil Alliance have described. Detailed biostratigraphic and petrographic studies have subsequently been carried out. Productive Series deposition was initiated by a dramatic relative sea-level fall which left the South Caspian an isolated basin fed by deeply incised precursors to the modern Volga, Amu Darya, and Kura rivers. Five facies associations have been recognised within the Productive Series at outcrop, encompassing a range of palaeoenvironments from alluvial braided river sandstones and conglomerates to delta-front siltstones and mudstones. The facies associations suggest a river-dominated, braid delta. Four idealised reservoir models can be recognised: fluvial, delta-plain, proximal delta-front and distal delta-front. Each has distinct grain-size and shale distributions. Studies of nearby oilfields suggest that these models form useful subsurface analogues. Flow simulation models suggest that each reservoir type has dramatically different performance. Productive Series sediments are typically loosely cemented and smectite rich, which may result in clay swelling and sand control problems. Localised reduction in reservoir quality is caused by fault-associated calcite cements. Proximal facies of the upper Productive Series contain porosity occluding gypsum cements. Palynology and nannopalaeontology have been applied to the Neogene sediments of Azerbaijan for almost the first time, and have given encouraging results, at least in terms of a broad biozonation. Micropaleontological analyses have also provided useful palaeoenvironmental data.

Ali-zade, A.A.; Guliyev, I.S.; Ateava, E.Z. [GIA, Baku (Azerbaijan)] [and others

1995-08-01

107

Sedimentology and Stratigraphy of the Upper Pennsylvanian – Lower Permian Systems of Western Nebraska, USA.  

E-print Network

??Depositional patterns and regional stratigraphic relationships in the carbonate-dominated Pennsylvanian and Permian deposits in western Nebraska are not well established due to poor surface exposure.… (more)

Gilleland, Chesney L

2011-01-01

108

Stratigraphy, sedimentology, and petrology of Upper Cretaceous Horsethief and St. Mary River formations, western Montana  

SciTech Connect

The Horsethief and St. Mary River formations were deposited along the Late Cretaceous epicontinental seaway, which then covered much of the western interior. The Horsethief, lower of the two formations, is divided into two facies sequences. Facies sequence A consist of coarsening-upward sequences of sandstones and interbedded shales. These facies comprise a barrier island system consisting of shoreface, dune, tidal channel, and lagoonal environments. Facies sequence B, deposited along the depositional strike, consists of a coarsening-upward sequence of vertically stacked distributary channels that thicken and become more abundant upsection. The St. Mary River Formation is divided into a lower and upper member. The lower member consists of shales, sandstones, limestones, and coals deposited in a lagoon landward of the barrier island system. The upper member contains trough cross-bedded, channel sandstones, overbank sandstones, shales, and carbonate-nodule horizons indicative of fluvial plain sedimentation. Petrographic analysis indicates the detritus of these formations was derived from a magmatic are provenance. Statistically significant correlations document a decrease in grain size as the distance of sediment transport increases within the entire section and within distinct environments, including middle shoreface, upper shoreface, and dune facies. The high percentage of volcanic constituents decreases as the distance of sediment transport increases and the grain size decreases. The recognition of these facies is significant because of the potentially important application associated with hydrocarbon source and reservoir conditions, as well as heavy mineral assemblages.

Fairhurst, W.

1983-03-01

109

Sedimentology, stratigraphy, and extinctions during the Cretaceous-Paleogene transition at Bug Creek, Montana  

Microsoft Academic Search

Bug Creek Valley, the source of an unusual and controversial Cretaceous-Paleogene coincidence of mammals, dinosaurs, pollen, and indium, exemplifies the importance of depositional process in the reconstruction of evolutionary events. Five sedimentary facies are recognized at Bug Creek: a cross-stratified sandstone, a green and purple siltstone, a lateral accretionary sandstone, a coal, and a variegated siltstone. Repeated fluvial channeling restricts

David E. Fastovsky; Robert H. Dott Jr.

1986-01-01

110

Sedimentology, stratigraphy, and extinctions during the Cretaceous-Paleogene transition at Bug Creek, Montana  

Microsoft Academic Search

Bug Creek Valley, the source of an unusual and controversial Cretaceous-Paleogene coincidence of mammals, dinosaurs, pollen, and iridium, exemplifies the importance of depositional process in the reconstruction of evolutionary events. Five sedimentary facies are recognized at Bug Creek: a cross-stratified sandstone, a green and purple siltstone, a lateral accretionary sandstone, a coal, and a variegated siltstone. Repeated fluvial channeling restricts

David E. Fastovsky

1986-01-01

111

Sedimentology and stratigraphy of the Kanayut Conglomerate, central Brooks Range, Alaska; report of 1980 field season  

USGS Publications Warehouse

The Upper Devonian Kanayut Conglomerate crops out along the crest of the Brooks Range of northern Alaska for a distance of almost 1000 km. It ranges in thickness from 2600 m in the Atigun River area to 700 m south of Anaktuvuk Pass and has been subdivided into four regionally persistent members: (a) the basal sandstone member, consisting of marine sandstone and shale with some conglomerate; (b) the lower shale member, consisting of nonmarine quartzite, conglomerate and shale; (c) the middle conglomerate member, consisting of nonmarine pebble and cobble conglomerate and quartzite; and (d) the Stuver Member, consisting of nonmarine sandstone and shale. The Kanayut conformably overlies the Upper Devonian marine Hunt Fork Shale and is conformably overlain by the Mississippian marine Kayak Shale. The Kanayut is wholly allochthonous and has probably been transported northward on a series of thrust plates. The basal sandstone member of the Kanayut Conglomerate, which overlies prodelta turbidites of the Hunt Fork Shale, contains marginal-marine coarsening-upward channel-mouth bar sequences. It is conformably overlain by the lower shale member. Measured sections of the nonmarine members of the Kanayut show that the lower shale member ranges in thickness from 120 m to 1115 m and consists of fining-upward cycles interpreted to have been deposited by meandering streams on a broad floodplain. These cycles contain, in ascending order, channelized basal conglomerate, trough cross-stratified sandstone, and ripple-marked siltstone. The cycles are interpreted to be channel and point-bar deposits. Individual cycles average about 10 m in thickness and are separated by intervals of black, brown or maroon floodplain shale deposits. These typically contain thin coarsening-upward units that probably represent prograding levee sequences and irregular and ungraded sandstone bodies interpreted to be crevasse-splay deposits. In the Okokmilaga River area, the lower shale member contains a distinctive coarse-grained unit which is burrowed and interpreted to represent a widespread marine incursion. The middle conglomerate member, which ranges in thickness from 155 m to 525 m, consists of braidplain deposits. It contains fining-upward couplets of conglomerate and parallel-stratified or cross-stratified sandstone that average 2-7 m in thickness. The couplets record deposition in channels and on bars of braided streams. The middle conglomerate member contains the largest clasts, little or no shale, and represents the maximum progradation of nonmarine sedimentation in the Kanayut depositional system. The Stuver Member consists of fining-upward cycles that resemble those of the lower shale member. It ranges in thickness from 160 m to 1400 m and grades upward into tidal and marginal-marine deposits of the Kayak Shale. Conglomerate in the Kanayut is compositionally very mature, averaging 82 percent white, gray, black or red chert clasts, 14 percent vein quartz clasts, 3 percent quartzite clasts, and less than I percent other lithologies, mainly argillite. Although red chert is locally abundant in the Shainin Lake-Galbraith Lake area, there is little variation in conglomerate composition in the Kanayut, suggesting derivation from a single major source terrane.

Nilsen, T.H.; Moore, T.E.; Balin, D.F.; Johnson, S.Y.

1982-01-01

112

Sedimentology: Recent developments and applied aspects  

SciTech Connect

This book reflects some of the developments which have occurred in sedimentology during the last two decades. It identifies problems of concern to sedimentologists. Topics covered include the following: loose-boundary hydraulics and fluid mechanics: selected advances since 1961; clastic facies models and facies analysis; recent shelf clastic sediments; deep-sea clastics; deep-sea pelagic sediments and palaeo-oceanography; facies analysis of volcaniclastic sediments; shallow-marine carbonate facies and facies models; diagenesis of shallow-marine carbonates; clastic diagenesis; sedimentary ore deposits; role of clastic sedimentology in the exploration and production of oil and gas in the North Sea; and carbonate facies analysis in the exploration for hydrocarbons: a case-study from the Cretaceous in the Middle East.

Brenchley, P.J.

1985-01-01

113

Workshop on quantitative dynamic stratigraphy  

SciTech Connect

This document discusses the development of quantitative simulation models for the investigation of geologic systems. The selection of variables, model verification, evaluation, and future directions in quantitative dynamic stratigraphy (QDS) models are detailed. Interdisciplinary applications, integration, implementation, and transfer of QDS are also discussed. (FI)

Cross, T.A.

1988-04-01

114

Stratigraphy of the crater Copernicus  

NASA Technical Reports Server (NTRS)

The stratigraphy of copernicus based on its olivine absorption bands is presented. Earth based spectral data are used to develop models that also employ cratering mechanics to devise theories for Copernican geomorphology. General geologic information, spectral information, upper and lower stratigraphic units and a chart for model comparison are included in the stratigraphic analysis.

Paquette, R.

1984-01-01

115

Amino acid racemization analysis (AAR) as a successful tool for dating Holocene coastal sediments: Stratigraphy of a barrier island spit (Southern Sylt/North Sea)  

NASA Astrophysics Data System (ADS)

Dating of Holocene sediments in shallow coastal areas of the German North Sea by conventional techniques is commonly problematic. In particular the marine reservoir effect of radiocarbon means that radiocarbon dating cannot be applied to sediments younger than about 400 years. Amino acid racemization dating (AAR) is a viable alternative for dating young sediments. The method is based on the determination of ratios of D and L amino acid enantiomers in organic matrices of biogenic carbonates. In this study we use AAR as a tool for dating Holocene barrier islands sediments. Based on an AAR derived chronological framework we develop a model of barrier spit accretion which describes the interaction between extreme events, fair weather coastal processes and sedimentary development that constrains the major episodes of barrier island evolution. The stratigraphy was defined using ground-penetrating radar (GPR) surveys complemented by sedimentological coring data. The stratigraphy is then conceptualised in a AAR chronostratigraphic framework to define a chronological order and allow the development of a stratigraphic model of the evolution of Southern Sylt. The AAR data provide high temporal resolution and have been used for dating stages of barrier spit accretion. The time lines are marked as storm surge generated erosion unconformities in the stratigraphic profile. Individual shells and shell fragments of Cerastoderma edule, Mya arenaria, Mytilus edulis and Scrobicularia plana have been accumulated by short-term storm events as shell layers associated with the erosion unconformities and have been dated by AAR. Time lines reveal that the barrier spit accretion occurred episodically, and is dependant on the provided rate of sand delivery. The general trend is that sequences young to the. South. The AAR derived time lines have been verified and correlated by historic maps and sea charts. It is apparent that spit enlargement at this site increased significantly during the Middle Ages (1593 - 1794) and was coupled with several intensive storm surges in this period. The findings indicate that when combined with GRR stratigraphy AAR provides useful results of high accuracy for dating stages of barrier spit progradation.

Tillmann, Tanja; Ziehe, Daniel

2014-05-01

116

Combining sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past water-column  

E-print Network

Combining sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past online 22 June 2013 Abstract Here, we present sedimentological, trace metal, and molecular evidence underscores the value of combining sedimentological, geochemical, and microbiological approaches

Wehrli, Bernhard

117

First Year Sedimentological Characteristics and Morphological Evolution of an Artificial Berm at Fort Myers Beach, Florida  

E-print Network

First Year Sedimentological Characteristics and Morphological Evolution of an Artificial Berm Methods and Data Analysis 29 Results and Discussion 34 Sedimentological Characteristics of the Artificial Project Area 45 Control Area Northwest of Berm 47 Discussion of Sedimentological Characteristics 49

US Army Corps of Engineers

118

Linking sedimentological, stratigraphic and diagenetic processes to understand unconventional reservoirs: the Upper Jurassic Vaca  

E-print Network

Linking sedimentological, stratigraphic and diagenetic processes to understand unconventional as to the scale of sedimentological variability within mudstone successions, and how related diagenetic alteration by Profs Taylor and Flint, to document the scale of sedimentological and diagenetic variability

Henderson, Gideon

119

Lithostratigraphy, geophysics, biostratigraphy, and strontium-isotope stratigraphy of the surficial aquifer system of eastern Collier County and northern Monroe County, Florida  

USGS Publications Warehouse

In 1997, ten cores were drilled in eastern Collier County and northern Monroe County, within the limits of the Big Cypress National Preserve. These cores represent a continuation of the study of seven cores in western Collier County begun in 1996 and reported in Weedman and others (1997) and Edwards and others (1998). This joint U.S. Geological Survey and Florida Geological Survey project is designed to acquire subsurface geologic and hydrologic data in southwest Florida to extend current ground-water models, thereby expanding the utility of these models for land and water management. In this report we describe the lithostratigraphy, geophysical logging, sedimentological analysis, dinocyst biostratigraphy, and strontium-isotope stratigraphy of these ten cores. The three geophysical logs (natural gamma-ray, induction conductivity, and neutron porosity) assumed to be related to formation lithology and water quality show that a number of clay-rich zones are present in all of the boreholes, and that pore-water conductivity increases with depth. The clay-rich zones are confirmed by visual examination of core material and sedimentological analysis. The relative transmissivity calculated at 10-foot-thick intervals shows that in six of the boreholes, high values are associated with the shallow aquifer in the 0-40 ft interval. Two of the boreholes (the most northerly and the most easterly) showed relatively higher values of transmissivity in permeable zones at or somewhat below 100 ft in depth. Core geology and logs indicate that the deeper aquifers are not more permeable than similar deeper zones in the other boreholes, but rather that the shallow aquifer appears to be less permeable in these two coreholes. The Arcadia (?) Formation was only penetrated in the deepest core where it is late Miocene in age. The Peace River Formation was penetrated in all but the two westernmost cores. It yields a late Miocene age, based on both dinocysts and strontium-isotope stratigraphy. The top is an irregular surface. Age and stratigraphic relations suggest that the upper part of the Peace River and lower part of the unnamed formation are at least partially equivalent laterally. The unnamed formation was recovered in every core. It is thinnest in the northernmost core and thickest to the west. Ages calculated from strontium isotopes range from 6.9 to 4.6 million years ago (late Miocene to early Pliocene). The top of the unnamed formation is deepest to the north and it becomes shallower to the southwest. The Tamiami Formation also was recovered in every core and consistently yields early Pliocene ages; it yields late Pliocene ages near the top in two cores. The age and lateral relations strongly suggest that the lower part of the Tamiami Formation and the upper part of the unnamed formation are lateral facies of each other. The Fort Thompson (?) Formation, Miami Limestone, and undifferentiated siliciclastic sediments and limestone at the very top of the cores were not dated.

Weedman, S.D.; Paillet, F.L.; Edwards, L.E.; Simmons, K.R.; Scott, T.M.; Wardlaw, B.R.; Reese, R.S.; Blair, J.L.

1999-01-01

120

Integrating sequence stratigraphy and rock-physics to interpret seismic amplitudes and predict reservoir quality  

NASA Astrophysics Data System (ADS)

This dissertation focuses on the link between seismic amplitudes and reservoir properties. Prediction of reservoir properties, such as sorting, sand/shale ratio, and cement-volume from seismic amplitudes improves by integrating knowledge from multiple disciplines. The key contribution of this dissertation is to improve the prediction of reservoir properties by integrating sequence stratigraphy and rock physics. Sequence stratigraphy has been successfully used for qualitative interpretation of seismic amplitudes to predict reservoir properties. Rock physics modeling allows quantitative interpretation of seismic amplitudes. However, often there is uncertainty about selecting geologically appropriate rock physics model and its input parameters, away from the wells. In the present dissertation, we exploit the predictive power of sequence stratigraphy to extract the spatial trends of sedimentological parameters that control seismic amplitudes. These spatial trends of sedimentological parameters can serve as valuable constraints in rock physics modeling, especially away from the wells. Consequently, rock physics modeling, integrated with the trends from sequence stratigraphy, become useful for interpreting observed seismic amplitudes away from the wells in terms of underlying sedimentological parameters. We illustrate this methodology using a comprehensive dataset from channelized turbidite systems, deposited in minibasin settings in the offshore Equatorial Guinea, West Africa. First, we present a practical recipe for using closed-form expressions of effective medium models to predict seismic velocities in unconsolidated sandstones. We use an effective medium model that combines perfectly rough and smooth grains (the extended Walton model), and use that model to derive coordination number, porosity, and pressure relations for P and S wave velocities from experimental data. Our recipe provides reasonable fits to other experimental and borehole data, and specifically improves the predictions of shear wave velocities. In addition, we provide empirical relations on normal compaction depth trends of porosity, velocities, and VP/VS ratio for shale and clean sands in shallow, supra-salt sediments in the Gulf of Mexico. Next, we identify probable spatial trends of sand/shale ratio and sorting as predicted by the conventional sequence stratigraphic model in minibasin settings (spill-and-fill model). These spatial trends are evaluated using well data from offshore West Africa, and the same well data are used to calibrate rock physics models (modified soft-sand model) that provide links between P-impedance and quartz/clay ratio, and sorting. The spatial increase in sand/shale ratio and sorting corresponds to an overall increase in P-impedance, and AVO intercept and gradient. The results are used as a guide to interpret sedimentological parameters from seismic attributes, away from the well locations. We present a quantitative link between carbonate cement and seismic attributes by combining stratigraphie cycles and the rock physics model (modified differential effective medium model). The variation in carbonate cement volume in West Africa can be linked with two distinct stratigraphic cycles: the coarsening-upward cycles and the fining-upward cycles. Cemented sandstones associated with these cycles exhibit distinct signatures on P-impedance vs. porosity and AVO intercept vs. gradient crossplots. These observations are important for assessing reservoir properties in the West Africa as well as in other analogous depositional environments. Finally, we investigate the relationship between seismic velocities and time temperature index (TTI) using basin and petroleum system modeling at Rio Muni basin, West Africa. We find that both VP and VS increase exponentially with TTI. The results can be applied to predict TTI, and thereby thermal maturity, from observed velocities.

Dutta, Tanima

121

Mesozoic-Cenozoic sequence stratigraphy of European basins  

SciTech Connect

The preliminary results of the project, [open quotes]Mesozoic-Cenozoic Sequence Stratigraphy of European Basins[close quotes] (introduced at a seminar in Dijon, France, on May 18-20, 1992), show that the Mesozoic-Cenozoic stratigraphic succession of western Europe can be subdivided into a series of transgressive-regressive facies cycles (second order, 3-50 m.y.) and related to tectonic events by subsidence analysis and regional geology. The distribution of the second-order cycles are shown on a series of transects that extend from the Mediterranean to the North Sea. Where possible, each transgressive-regressive phase has been subdivided into a series of higher frequency sequence cycles (third order, 0.5-3 m.y.). These sequence cycles are identified in regions with good outcrops and biostratigraphic control. The sequence stratigraphy interpretation of these outcrop sections provides documentation for the age and distribution of the second- and third-order stratigraphic cycles of western Europe. Subsurface seismic and well data from the North Sea Basin, Paris basin, and the Mediterranean area are interpreted in terms of sequence stratigraphy and correlated to the outcrop reference sections. Chronobiostratigraphy and numerical ages are based on a series of new charts made especially for this project that show the latest correlation of the biostratigraphic zones for both microfossils and macrofossils across Europe. The charts also include a numerical time scale that reconciles the differences between existing time scales.

Vail, P.R. (Rice Univ., Houston, TX (United States)); Jacquin, T. (Ecole des Mines de Paris, Paris (France))

1993-09-01

122

Sedimentological analysis using geophysical well logs  

SciTech Connect

The application of geophysical well logs in sedimentology and stratigraphic prospecting holds great promise in solving a number of geological problems. A suite of logs provides data on a wide range of rock properties: vertical and lateral variation of resistivity, natural polarization, natural and induced radioactivity, shear strength, and acoustic properties. Each of these properties is controlled by the depositional environment of the sediments and their later diagenesis. The attention of geologists and geophysicists is drawn to new techniques in the interpretation of geophysical well logs for exploration, appraisal, and development of oil and gas fields. The relationship between geophysical logs and depositional environments is explored. Bulk composition, rock structure, and texture and facies variation can be quantified by electric log parameters. Also, the possibility of using logs to demonstrate long- and short-period sedimentary cycles is demonstrated. Methods of sedimentological analysis using geophysical well logs are demonstrated. The importance of a genetic approach in the interpretation of geological sequences and paleogeological reconstructions is emphasized using examples taken from oil and gas prospecting operations in the Ukraine.

Izotova, T.S. (Ukrainian State Geological Research Institute, Kiev (Ukraine))

1993-09-01

123

CAMBRIAN STRATIGRAPHY AND PALEONTOLOGY OF NORTHERN ARIZONA AND SOUTHERN NEVADA  

E-print Network

#12;CAMBRIAN STRATIGRAPHY AND PALEONTOLOGY OF NORTHERN ARIZONA AND SOUTHERN NEVADA THE 16TH FIELD. A., and Foster, J. R., (editors), 2011, Cambrian Stratigraphy and Paleontology of Northern Arizona Stratigraphy and Paleontology of Northern Arizona and Southern Nevada REGIONAL SETTING AND GENERAL STRATIGRAPHY

Mateo, Jill M.

124

Sedimentology of coarse-clastic beach-ridge deposits, Essex, southeast England  

NASA Astrophysics Data System (ADS)

The distinction of cheniers from other types of beach ridge can often be problematic. The stratigraphy, sedimentology and geomorphological development of sand- and gravel-rich beach ridges at three sites on the northern Essex coast, England were determined using ground-penetrating radar (GPR), ground-truthing trenches and auger holes, and historical-aerial photograph analysis. The 900 MHz GPR system used achieved a maximum vertical resolution between 0.02 and 0.06 m. There was good correspondence between the radar stratigraphy obtained from time-migrated radar reflection profiles and the nature and form of bounding surfaces, sets of lamination, beds and bedsets observed in trenches. Data for one of the study sites (Colne Point) illustrate a complex beach-ridge stratigraphy and sequence of development that confirms they are not true cheniers. Instead, the ridges form part of both retrogradational and progradational barrier-spit sequences. Chenier designation at the other two study sites (Foulton Hall and Stone Point) is more straightforward, as the beach ridges lie at the junction between actively eroding mudflat and saltmarsh. However, despite the distinction between the barrier-spit beach ridges and the cheniers, the same types of deposit are recognised in both, indicating similar formative processes. Washover-sheet deposits consist of low-angle (<5°), sub-parallel, landward-dipping stratification, which is concordant with bounding surfaces above and below. Washover sheets develop when high-wave energy/storm-related overwash moves landward onto unflooded marsh or lagoonal surfaces. Washover-delta deposits are characterised by high-angle cross-stratification (up to 28°) that downlaps onto the underlying marsh or lagoonal surface. Washover deltas develop when overwash enters a significant body of standing water to landward, such as a flooded marsh or lagoon. Alternations between washover-sheet and washover-delta development are seen in many instances, but their time scale is unclear due to paucity of detailed information regarding overwash sedimentation rates, or chenier and berm-ridge migration rates. Similarity of the internal structure in both the cheniers and barrier-spit beach ridges confirms that this criterion alone cannot be used to distinguish different types of beach-ridge deposit. Detailed stratigraphic data, preferably complemented by direct evidence for the geomorphological context in which the ridge developed, are also required.

Neal, Adrian; Richards, Julie; Pye, Ken

2003-12-01

125

Large-scale River Channel Shifts on the Western Indo-Gangetic Plains and their implications for the Bronze-age Harappan Civilisation Settlement Patterns  

NASA Astrophysics Data System (ADS)

The distribution of settlements in ancient societies is commonly linked to the courses of large river systems. The Bronze Age Harappan civilisation (4800-3500BP) is no exception with the major sites of Harappa and Mohenjo-Daro located along the Indus river system. However, the largest collection of Harappan archaeological sites are associated with the postulated surface trace of a large palaeo-river channel in the drainage divide tract between the Ganges and Indus river systems, where no major river currently flows. It has been proposed that this palaeo-channel was occupied by a major river sourced in the Himalaya, and that this river provided water resources to sustain the extensive Harappan sites located along its ancient course. The abrupt abandonment of urban centres here at ~3500 BP has been explained as a consequence of river diversion, although alternative explanations for cultural decline have also been entertained. These hypotheses have remained untested because the stratigraphy and chronology of the postulated palaeochannel has never been determined. We use a combination of satellite image analysis, subsurface geophysical analysis and sediment coring to analyse the large-scale planform geometry, and detailed sedimentary and stratigraphic nature of the postulated palaeochannel in NW India. In particular we focus our analysis on a tract of the proposed channel adjacent to the major Harappan urban centre of Kalibangan in Rajastan State. We find that the surface trace of a postulated palaeochannel on satellite imagery is confirmed by subsurface geophysical investigation and detailed coring. In this presentation we will describe the remotely sensed character of the palaeochannel on satellite imagery, and the detailed stratigraphy and sedimentology based on resistivity investigations and sedimentological analysis of the cores. We will consider how changes in the course of the palaeochannel may have influenced settlement patterns of the Harappan civilisation in present day NW India.

Gupta, S.; Sinha, R.; Mason, P.; Yadav, G.; Singh, A.; Carter, A.; Murrey, A.

2009-12-01

126

Eolian cover sands: a sedimentologic model and paleoenvironmental implications  

SciTech Connect

In periglacial areas, accumulations of eolian sand commonly form low-relief blankets without well-developed dunes. Internally, these sandsheet deposits exhibit subhorizontal lamination rather than high-angle cross-bedding. Such cover sands of late-Pleistocene age mantle extensive areas in northern Europe, but have been reported more rarely from North America. The processes by which cover sands, as opposed to dunes, accumulate have not yet been determined conclusively. Wind ripples and sand dunes do not form a continuum; flow separation and avalanching and negligible in the former and vital in the latter. Accretion of a sand patch into a mound sufficient to cause flow separation and dune growth requires a consistently available supply of loose sand. In cover-sand areas, sand may be immobilized prior to dune development by several factors: (1) a sparse vegetation cover, (2) moist ground conditions, (3) snow cover, and (4) a shallow permafrost table and/or an ice-cemented active layer. Detailed sedimentologic studies may allow discrimination among these various controls. The importance of the individual controlling factors can vary seasonally in a given deposit, as well as between deposits in different paleogeographic settings. However, all factors imply more mesic conditions than those associated with many dune deposits. The association of cover sands with paraboloid dunes is also consistent with somewhat moist conditions. The relatively mesic nature of cover sands controls their Pleistocene distribution; they become decreasingly important relative to dunes in maritime-to-continental transects across Alaska and northern Europe.

Lea, P.D.

1985-01-01

127

Sedimentology by satellite: Space age approach to the coastal zone  

SciTech Connect

Satellites such as LANDSAT (EOSAT) and SPOT, with a variety of spectral configurations, combined with computer interpretive systems will allow us to synoptically evaluate coastal systems at relatively short intervals. Resolution of satellite images measured in meters dictates concentration on large-scale changes and fluxes. In areas of relatively clear water, such as the Mediterranean Sea or the eastern Gulf of Mexico, some satellite spectra will allow us to map below the sea surface and hence determine how the innermost shelf changes with time. To illustrate these points, we studied the barrier island system of the central west Florida coastline (USA) before and after the 1985 hurricane season. Two major storms impacted this region during that period. By computer overlaying before and after images, we were able to map changes in the barrier islands and to quantify acreage gained and lost. We were also able to detect and map changes in the submarine portions of the system, especially in the ebb and flood tidal deltas associated with inlets. The third dimension can be added by surveying the submarine features with high-resolution geophysics. Applications of this kind hold the promise of a new era in investigating beach/barrier islands and their relationship with the inner continental shelf.

Doyle, L.J.; McGarry, G.

1988-08-01

128

Stratigraphic Heterogeneity of a Holocene Ooid Tidal Sand Shoal: Lily Bank, Bahamas  

E-print Network

........................................................................................................................ 5 Regional Trends in Reflectors and Units .................................................................................................. 7 SEDIMENTOLOGY OF THE HOLOCENE SUCCESSION... ...................................................................... 8 Lagoon Sedimentology and Stratigraphy .................................................................................................. 8 Channel (Inter-bar) Sedimentology and Stratigraphy...

Sparks, Andrew

2011-08-31

129

Stratigraphy and structure of coalbed methane reservoirs in the United States: An overview  

Microsoft Academic Search

Stratigraphy and geologic structure determine the shape, continuity and permeability of coal and are therefore critical considerations for designing exploration and production strategies for coalbed methane. Coal in the United States is dominantly of Pennsylvanian, Cretaceous and Tertiary age, and to date, more than 90% of the coalbed methane produced is from Pennsylvanian and Cretaceous strata of the Black Warrior

Jack C Pashin

1998-01-01

130

Stratigraphy and chronology of late Quaternary andesitic tephra deposits, Tongariro Volcanic Centre, New Zealand  

Microsoft Academic Search

A stratigraphy and chronology of andesitic tephras erupted from Mt Ruapehu, and other volcanoes of Tongariro Volcanic Centre, is constructed from the tephra record preserved on the southeastern Mt Ruapehu ring plain. Here, tephras of late Quaternary age (c. 22,500 years B.P. to present) are found interbedded with local laharic and fluvial deposits, and with distal rhyolitic tephras from Taupo

S. L. Donoghue; V. E. Neall; A. S. Palmer

1995-01-01

131

Sequence stratigraphy, paleoclimate, and tectonics of coal-bearing strata  

SciTech Connect

The origin of coal-bearing strata has been debated vigorously for more than a century, and with the emergence of coalbed methane as a major energy resource and the possibility of sequestering greenhouse gas in coal, this debate has never been more relevant. This volume contains 10 chapters on coal-bearing strata of Carboniferous through Tertiary age and is based on a special session that was held at an AAPG Annual Meeting in New Orleans. Contributors have employed a multitude of approaches ranging from basin analysis to plant taphonomy to support a variety of views on the sequence stratigraphy, paleoclimate, and tectonics of coal-bearing strata.

Jack C. Pashin; Robert A. Gastaldo (eds.)

2004-07-15

132

Fluvial-deltaic sedimentation and stratigraphy of the ferron sandstone  

USGS Publications Warehouse

East-central Utah has world-class outcrops of dominantly fluvial-deltaic Turonian to Coniacian aged strata deposited in the Cretaceous foreland basin. The Ferron Sandstone Member of the Mancos Shale records the influences of both tidal and wave energy on fluvial-dominated deltas on the western margin of the Cretaceous western interior seaway. Revisions of the stratigraphy are proposed for the Ferron Sandstone. Facies representing a variety of environments of deposition are well exposed, including delta-front, strandline, marginal marine, and coastal-plain. Some of these facies are described in detail for use in petroleum reservoir characterization and include permeability structure.

Anderson, P.B.; Chidsey, T.C., Jr.; Ryer, T.A.

1997-01-01

133

Stratigraphy and sequence stratigraphy of the Moscovian in the Donets basin  

Microsoft Academic Search

New results are presented on the stratigraphy based on Fusulinids and Palynomorphs and the sequence stratigraphy of the Moscovian in the Donets basin. They have been developed by comparison of our observations on cross-sections near Artemovsk and the published coal mine logs of Artemovsk Geological Survey. The Moscovian of the Donets basin is equivalent to the uppermost Westphalian B and

A. Izart; C. Briand; D. Vaslet; D. Vachard; R. Coquel; A. Maslo

1996-01-01

134

Seismic stratigraphy of the Bahamas  

SciTech Connect

Seismic reflection profiles from the Straits of Florida, Northwest Providence Channel, Tongue of the Ocean, and Exuma Sound reveal a seismic stratigraphy characterized by a series of prograding Upper Cretaceous and Tertiary seismic sequences with seismic velocities generally less than 4 km/sec overlying a Lower Cretaceous section of low-amplitude reflections which are more nearly horizontal than the overlying prograding clinoforms and have seismic velocities greater than 5 km/sec. The prograding units are detrital shallow-water carbonates shed from nearby carbonate banks into deep intrabank basins that were established in the Late Cretaceous. The Lower Cretaceous units are probably shallow-water carbonate banks that were drowned in the middle Cretaceous but which, during the Early Cretaceous, extended from Florida throughout the Bahamas region. The seismic reflection profiles reveal a sharp angular unconformity at 5-sec two-way traveltime in northwest Tongue of the Ocean, suggesting a rift-drift unconformity and deposition on thinned continental crust. No such unconformity is seen in central and southeast Tongue of the Ocean or in Exuma Sound, suggesting that these areas are built on oceanic crust.

Ladd, J.W.; Sheridan, R.E.

1987-06-01

135

Mid-Holocene strengthening of the Southern Westerlies in South America --Sedimentological evidences from  

E-print Network

Mid-Holocene strengthening of the Southern Westerlies in South America -- Sedimentological layers, a composite sedimentological record of almost 25 m was established covering the last ~16,000 cal yr. Sedimentological and petrophysical analysis of the cores revealed the establishment of a dominant

Gilli, Adrian

136

Lake Level Controlled Sedimentological I Heterogenity of Oil Shale, Upper Green River  

E-print Network

Chapter 3 Lake Level Controlled Sedimentological 1:'_i 'I I Heterogenity of Oil Shale, Upper Green-shale and has enormous potential to meet global energy requirements, yet a detailed sedimentological Formation is obvious. Yet, sedimentology of the oil-shale bearing units of the Green River Formation

Gani, M. Royhan

137

Author's personal copy Reverse engineering mother nature --Shale sedimentology from an  

E-print Network

Author's personal copy Review Reverse engineering mother nature -- Shale sedimentology from of the sedimentology of shales can take a variety of forms. At its simplest one can experiment with suspensions conducted by hydraulic engineers, the transfer of that knowledge to sedimentology is hampered by the fact

Polly, David

138

David A. Katz $ Comparative Sedimen-tology Laboratory, University of Miami, 4600  

E-print Network

Sedimentology Laboratory. His research investigates the earliest diagenesis and geochemistry of modern Sedimentology Laboratory. He received his Ph.D. from the Swiss Institute of Technology (Eidgeno¨ssische Technische Hochschule) in Zurich, Switzerland. His field research focuses on sedimentology and se- quence

Swart, Peter K.

139

The Cretaceous/ Tertiary boundary: sedimentology and micropalaeontology at El Mulato section, NE Mexico  

E-print Network

The Cretaceous/ Tertiary boundary: sedimentology and micropalaeontology at El Mulato section, NE and sedimentological analysis of this transition at the El Mulato section (NE Mexico), in order to infer the little Palaeogene Velasco Formation, there is a 2-m-thick Clastic Unit. Strati- graphical and sedimentological ana

Royer, Dana

140

Sequence Stratigraphy of the Glenshaw Formation (MiddleLate  

E-print Network

Sequence Stratigraphy of the Glenshaw Formation (Middle­Late Pennsylvanian) in the Central. L., 2004, Sequence stratigraphy of the Glenshaw Formation (middle­late Pennsylvanian) in the central Appalachian basin, in J. C. Pashin and R. A. Gastaldo, eds., Sequence stratigraphy, paleoclimate

Martino, Ronald L.

141

CAMBRIAN STRATIGRAPHY AND PALEONTOLOGY OF NORTHERN ARIZONA AND SOUTHERN NEVADA  

E-print Network

#12;CAMBRIAN STRATIGRAPHY AND PALEONTOLOGY OF NORTHERN ARIZONA AND SOUTHERN NEVADA THE 16TH FIELD. A., and Foster, J. R., (editors), 2011, Cambrian Stratigraphy and Paleontology of Northern Arizona and Southern Nevada: Museum of Northern Arizona Bulletin 67, 321 p. #12;Cambrian Stratigraphy and Paleontology

Mateo, Jill M.

142

CAMBRIAN STRATIGRAPHY AND PALEONTOLOGY OF NORTHERN ARIZONA AND SOUTHERN NEVADA  

E-print Network

#12;CAMBRIAN STRATIGRAPHY AND PALEONTOLOGY OF NORTHERN ARIZONA AND SOUTHERN NEVADA THE 16TH FIELD. A., and Foster, J. R., (editors), 2011, Cambrian Stratigraphy and Paleontology of Northern Arizona! software ( National Geographic, 2002). 236 #12;Cambrian Stratigraphy and Paleontology of Northern Arizona

Mateo, Jill M.

143

Palynology, sedimentology and palaeoecology of the late Holocene Dead Sea  

Microsoft Academic Search

Palynological and sedimentological studies were performed at two Holocene profiles in erosion gullies (Ze’elim and Ein Feshkha) which dissect the retreating western shore of the Dead Sea. The aim of the project was to analyse possible links between climate, lithology, and vegetation development. The section in Ze’elim shows both lacustrine and fluvial sediments, whereas sedimentation at Ein Feshkha is predominantly

Frank Harald Neumann; Elisa J. Kagan; Markus J. Schwab; Mordechai Stein

2007-01-01

144

Sedimentology and geochemistry of saline lakes of the Great Plains  

Microsoft Academic Search

Southern Saskatchewan and portions of adjacent Alberta, North Dakota and Montana are occupied by hundreds of saline and hypersaline lakes ranging in size from small prairie potholes (less than 1 km2) to relatively large bodies of water (greater than 300 km2). From a sedimentological perspective, distinction must be made between two basic types of saline lakes: playas and perennial lakes.

W. M. Last; T. H. Schweyen

1983-01-01

145

Sedimentology of coal and coal-bearing sequences  

SciTech Connect

Papers on all aspects of coal sedimentology are presented. The emphasis of the book is on coal depositional environments and facies models, and the main topics covered are coal environments, composition and geochemistry, facies models of associated clastic rocks, applications of facies models to coal mining, and sedimentary tectonics of coal basins.

Rahmani, R.A.; Flores, R.M.

1985-01-01

146

1981 symposium on surface-mining hydrology, sedimentology, and reclamation  

SciTech Connect

Papers presented at the symposium are included in this volume. Discussions are presented under the following headings: reclamation; special applications; hydrology; sewage sludge application; sedimentology; and wildlife and recreation. The proceedings contains 80 papers, 74 of which are abstracted separately for inclusion in the Energy Data Base. (DMC)

Graves, D.H. (ed.)

1981-01-01

147

Morphology, sedimentology and stratigraphic implication of debris-covered glacier deposits from the LGM and Lateglacial (Eastern Alps, Austria)  

NASA Astrophysics Data System (ADS)

Understanding the genesis of Quaternary sediments is crucial for establishing a climato-stratigraphy and, further on, to infer paleoclimatic conditions, if possible. Especially diamictons in the high-mountain environment may be formed by variety of processes, i.e. glacial, periglacial and gravitational. On the other hand, the interpretation of morphological features might be ambiguous as for example ridges may document latero-frontal dump moraines, flow of a rock avalanche event or constituents of a rock-glacier. In addition, equilibrium line altitudes (ELAs) of paleo-glaciers are mostly based on calculations using the reconstructed glacier size and applying a more or less fixed accumulation area ration (e.g. AAR - method). However, such ELAs are of no use for stratigraphic correlations and climatic considerations, if the former glacial system was strongly influenced by supraglacial debris deriving from steep back walls of cirques. We present two examples of reconstructed debris-covered or more specifically debris-mantled paleo-glaciers, their geological and morphological setting as well as their documented sedimentology and morphology. The first example is from the easternmost part of the European Alps (Northern Calcareous Alps / Schneeberg mountains / Puchberg) where an up to 60 m high moraine systems of LGM age shows some striking morphological similarities with relict rock glacier. However, based especially on lithofacies analyses as well as on the lithology of the matrix a glacial genesis could be proven. Lateglacial glacier deposits from the interior of the Alps (Lienz Dolomites / area of Karlsbader Hütte) display a quite similar glacial system. The geometry of the deposits in relation to proglacial sturzstrom sediments, showing typical indications of dynamic fragmentation, and the amount of angular, passively transported clasts in the till point to a rock avalanche event which had hit the glacier surface during a glacier advance. As the glacial system shows the morphostratigraphic characteristics of Younger Dryas (Egesen) stadial with multiple, sharp crested moraine ridges (e.g. Ivy-Ochs et al. 2008), the unusual large glacier extent is due to the rock avalanche debris cover and its insulating effect. In both cases the maximum elevation of lateral moraines (MELM - method) gave the most reliable estimates of ELAs with reconstructed low AARs of around 0.5 compared to the standard assumption for Lateglacial glaciers with a ratio around 0.65. Thus, stratigraphic correlations of moraines should be done not until morphological features and lithofacies have been analyzed considering the whole geological setting. Ivy-Ochs, S., Kerschner, H., Reuther, A., Preusser, F., Heine, K., Maisch, M., Kubik, P.W. and Ch. Schlüchter (2008):Chronology of the last glacial cycle in the Northern European Alps. Journal of Quaternary Science 23(6-7), 559-573.

Reitner, Jürgen M.; Seidl, Sabrina; Wagreich, Michael

2013-04-01

148

Floodplain deposits, channel changes and riverbank stratigraphy of the Mekong River area at the 14th-Century city of Chiang Saen, Northern Thailand  

Microsoft Academic Search

Riverbank stratigraphy and paleochannel patterns of the Mekong River at Chiang Saen provide a geoarchaeological framework to explore for evidence of Neolithic, Bronze-age, AD 5th Century Yonok and AD 14–16th Century Lan Na Cultures. Typical bank stratigraphy charted on the Thailand side is imbricate cobble gravel overlain by 5–10 m of reddish-brown sandy silt. The silt section is composed chiefly of

Spencer H. Wood; Alan D. Ziegler; Tharaporn Bundarnsin

2008-01-01

149

A new stratigraphy for the islands of the Sumatran Forearc, Indonesia  

NASA Astrophysics Data System (ADS)

The Sumatran Forearc of western Indonesia contains a number of islands where extensive exposures of basement rocks and their sedimentary cover may be examined. The islands, such as Nias and the Batu Islands, are located along the outer-edge of the Sumatran Forearc, whilst others, including the Banyak Island Group and Pini Island, lie within the forearc basin. Detailed sedimentological, palaeontological and palaeobathymetric data from the Tertiary strata from the forearc region require a new stratigraphy, as previous stratigraphic schemes have not explained the variations across the region adequately. This stratigraphy, developed initially from detailed data collected on Nias and the Banyak Islands, can fully account for the successions of sedimentary rocks on the Banyak and Batu Islands and Siberut and explains many of the apparent inconsistencies between previous stratigraphies. A basement complex and six new formations are formally defined in this paper; important sedimentological differences between these formations represent key stages in the evolution of the outer part of the Sumatran Forearc. Studies of the basement rocks across the forearc area suggest the basement is inhomogeneous; large intact sections of ophiolitic material occur in some areas, whilst there is evidence for both oceanic and continental basement in others. Such heterogeneity is to be expected in a long lived obliquely convergent margin. In Oligocene-earliest Miocene times extension of the heterogeneous basement is inferred through indirect evidence. Palaeobathymetric data from the Oyo Formation indicates that the initial deposition in the newly formed extensional sub-basins on Nias was, in most areas, deep marine, in many cases below the CCD. Detailed biostratigraphic analyses and structural and geochronological studies indicate a major Early Miocene unconformity in the western (Lahewa Sub-basin) and parts of central Nias (Mujoi Sub-basin). This unconformity was developed as a direct result of a period of basin inversion that affected western parts of Nias. Whilst sub-aerial erosion occurred in parts of western Nias, conformable deposition of the Gawo and Olodano Formation continued in the Gomo and eastern parts of the Mujoi Sub-basins. The shallow marine sedimentary rocks of the Olodano Formation tended to accumulate on intra sub-basinal highs whose position was controlled by active faults that transected the sub-basins. The sedimentary record reveals that the Lower and Middle Miocene phases of differential uplift and subsidence had ceased by the Late Miocene. A massive influx of Himalayan derived Bengal Fan sediments reached the Sunda Trench in the Sumatra area in the late Middle Miocene. Continued addition of Bengal Fan material to the accretionary wedge south-west of Nias resulted in steady plate deflection and subsidence through flexural processes in forearc basin areas. The flexural consequence of increased load added to the prism, and associated subsidence history is documented by the sedimentary record on Nias where the shallow marine Olodano Formation passes up into the neritic to upper bathyal Lahomie Formation. The Pliocene unconformity which is observed over all areas studied in the forearc is well constrained by structural, biostratigraphic and sedimentological studies. The unconformity represents the initiation of a major phase of uplift and deformation that continues to the present day. Rapid uplift of the outer arc ridge and deformation of the prism during the Pliocene led to increased subsidence landward of the deformation. The rapid subsidence of the forearc basin landward of the outer-arc ridge has contributed greatly to the "apparent" differences between the forearc basin and the outer-arc ridge at the present day: two areas with remarkably similar pre-Pliocene histories now have remarkably different physiographies.

Samuel, M. A.; Harbury, N. A.; Bakri, A.; Banner, F. T.; Hartono, L.

1997-08-01

150

Sedimentology of mega-scale glacial lineations on the Dubawnt Lake Palaeo-Ice Stream bed, Canada and implications for lineation genesis  

NASA Astrophysics Data System (ADS)

Mega-scale glacial lineations (MSGLs) are highly elongate, subglacial landforms produced beneath zones of fast-flowing ice. While qualitative data on their morphology have existed for several decades, studies of their composition and sedimentology are comparatively rare. Sediment exposures along the course of the Finnie River in Nunavut, northern Canada, provide a window into the internal stratigraphy and sedimentology of MSGLs formed by the Dubawnt Lake Palaeo-Ice Stream during regional deglaciation of the Laurentide Ice Sheet. Stratigraphic sections record evidence for an initial advance of ice into the study area followed by ice sheet recession and deposition of glacifluvial and glacilacustrine outwash. Subsequently, the Dubawnt Lake Palaeo-Ice Stream overrode and reworked this outwash subglacially forming an 'MSGL till'. This till comprises a sandy, red diamicton facies, forming the core of the MSGL ridges and containing variably deformed lenses, stringers and rafts of outwash. The sedimentology of this diamicton is consistent with an origin as a glacitectonite and hybrid till formed by a combination of non-pervasive subglacial sediment deformation and lodgement. Facies variations from stratified to massive diamicton reflect, in turn, variations in strain and subglacial transport distance. The occurrence of stratified glacifluvial sediments within these ridges and the well-preserved nature of many of the sandy inclusions within the diamicton imply relatively short transport distances and incomplete mixing. MSGLs under the Dubawnt Lake Palaeo-Ice Stream formed through a combination of subglacial erosion and deposition. This included non-pervasive, subglacial sediment deformation and the reworking of pre-existing sediment depocentres during streaming flow. These results highlight the importance of sediment supply to MSGL formation with the presence of abundant pre-existing sediments which were subsequently overridden being critical to lineation formation.

O'Cofaigh, Colm; Stokes, Chris R.; Lian, Olav B.; Clark, Chris D.; Tulaczyk, Slawek

2014-05-01

151

Stratigraphy and sedimentology of the Permian Talaterang and Shoalhaven Groups in the southernmost Sydney Basin, New South Wales  

Microsoft Academic Search

The Permian (Sakmarian?Artinskian) Talaterang and Shoalhaven Groups form the basal part of the Sydney Basin succession at its southernmost onshore extremity. A new stratigraphic model is proposed for the southern Sydney Basin and, although the previous group division is retained, considerable rearrangement of formations within and between the groups has been necessary as a result of recent field work. The

S. C. Tye; C. R. Fielding; B. G. Jones

1996-01-01

152

Rudist formations in mixed siliciclastic-carbonate depositional environments, Upper Cretaceous, Austria: stratigraphy, sedimentology, and models of development  

Microsoft Academic Search

The upper Turonian to lower Campanian succession (Lower Gosau Subgroup) of the Northern Calcareous Alps, Austria, provides a model for the development of rudist formations on wave-dominated, mixed siliciclastic-carbonate shelves that were situated on top of an accretionary wedge. The rudist formations are present either within parasequences or in non-cyclic transgressive successions, and include (a) skeletal mounds up to about

Diethard Sanders; Josep Maria Pons

1999-01-01

153

Stratigraphy and Sedimentology of the Late Cretaceous (Coniacian) Muskiki and Marshybank Members, Southern Alberta and Northwestern Montana.  

E-print Network

??A high-resolution allostratigraphic study of the Coniacian Muskiki and Marshybank members of the Wapiabi Formation in southern Alberta revealed a southwest thickening wedge of mudstone-dominated… (more)

Grifi, Meriem

2012-01-01

154

Sedimentology and stratigraphy of the Kanayut Conglomerate, central and western Brooks Range, Alaska; report of 1981 field season  

USGS Publications Warehouse

The Upper Devonian and Lower Mississippian(?) Kanayut Conglomerate forms a major stratigraphic unit along the crest of the Brooks Range of northern Alaska. It crops out for an east-west distance of about 900 km and a north-south distance of about 65 km. The Kanayut is wholly allochthonous and has probably been transported northward on a series of thrust plates. The Kanayut is as thick as 2,600 m in the east-central Brooks Range. It thins and fines to the south and west. The Kanayut forms the middle part of the allochthonous sequence of the Endicott Group, an Upper Devonian and Mississippian clastic sequence underlain by platform limestones of the Baird Group and overlain by platform limestone, carbonaceous shale, and black chert of the Lisburne Group. The Kanayut overlies the marine Upper Devonian Noatak Sandstone or, where it is missing, the marine Upper Devonian Hunt Fork Shale. It is overlain by the marine Mississippian Kayak Shale. The Kanayut Conglomerate forms the fluvial part of a large, coarse-grained delta that prograded to the southwest in Late Devonian time and retreated in Early Mississippian time. Four sections of the Kanayut Conglomerate in the central Brooks Range and five in the western Brooks Range were measured in 1981. The sections from the western Brooks Range document the presence of fluvial cycles in the Kanayut as far west as the shores of the Chukchi Sea. The Kanayut in this area is generally finer grained than it is in the central and eastern Brooks Range, having a maximum clast size of 3 cm. It is probably about 300 m thick. The upper and lower contacts of the Kanayut are gradational. The lower Kanayut contains calcareous, marine-influenced sandstone within channel deposits, and the upper Kanayut contains probable marine interdistributary-bay shale sequences. The members of the Kanayut Conglomerate cannot be differentiated in this region. In the central Brooks Range, sections of the Kanayut Conglomerate at Siavlat Mountain and Kakivilak Creek are typically organized into fining-upward fluvial cycles. The maximum clast size is about 3 cm in this area. The Kanayut in this region is 200-500 m thick and can be divided into the Ear Peak, Shainin Lake, and Stuver Members. The upper contact of the Kanayut with the Kayak Shale is very gradational at Kakivilak Creek and very abrupt at Siavlat Mountain. Paleocurrents from fluvial strata of the Kanayut indicate sediment transport toward the west and south in both the western and central Brooks Range. The maximum clast size distribution generally indicates westward fining from the Shainin Lake region.

Nilsen, T.H.; Moore, T.E.

1982-01-01

155

Sedimentology and stratigraphy of the Palisades, Lower Comanche, and Arroyo Grande areas of the Colorado River Corridor, Grand Canyon, Arizona  

USGS Publications Warehouse

This report analyzes various depositional environments in three archaeologically significant areas of the Colorado River corridor in Grand Canyon. Archaeological features are built on and buried by fluvial, aeolian, and locally derived sediment, representing a complex interaction between geologic and cultural history. These analyses provide a basis for determining the potential influence of Glen Canyon Dam operations on selected archaeological sites and thus for guiding dam operations in order to facilitate preservation of cultural resources. This report presents initial results of a joint effort between geologists and archaeologists to evaluate the significance of various depositional processes and environments in the prehistoric formation and modern preservation of archaeological sites along the Colorado River corridor in Grand Canyon National Park. Stratigraphic investigations of the Palisades, Lower Comanche, and Arroyo Grande areas of Grand Canyon yield detailed information regarding the sedimentary history at these locations. Reconstruction of past depositional settings is critical to a thorough understanding of the geomorphic and stratigraphic evolution of these three archaeologically significant areas. This examination of past sedimentary environments allows the relative significance of fluvial, aeolian, debris-fan, and slope-wash sedimentary deposits to be identified at each site. In general the proportion of fluvial sediment (number and thickness of flood deposits) is shown to decrease away from the river, and locally derived sediment becomes more significant. Flood sequences often occur as 'couplets' that contain a fluvial deposit overlain by an interflood unit that reflects reworking of fluvial sediment at the land surface by wind and local runoff. Archaeological features are built on and buried by sediment of various depositional environments, implying a complex interaction between geologic and cultural history. Such field analysis, which combines geological and archaeological information and techniques, can provide a basis for future determination of the effects of Glen Canyon Dam operations on selected areas of the river corridor. This knowledge is essential to the development of preservation strategies for cultural resources in Grand Canyon.

Draut, Amy E.; Rubin, David M.; Dierker, Jennifer L.; Fairley, Helen C.; Griffiths, Ronald E.; Hazel, Joseph E., Jr.; Hunter, Ralph E.; Kohl, Keith; Leap, Lisa M.; Nials, Fred L.; Topping, David J.; Yeatts, Michael

2005-01-01

156

The orbital record in stratigraphy  

NASA Technical Reports Server (NTRS)

Orbital signals are being discovered in pre-Pleistocene sediments. Due to their hierarchical nature these cycle patterns are complex, and the imprecision of geochronology generally makes the assignment of stratigraphic cycles to specific orbital cycles uncertain, but in sequences such as the limnic Newark Group under study by Olsen and pelagic Cretaceous sequence worked on by our Italo-American group the relative frequencies yield a definitive match to the Milankovitch hierarchy. Due to the multiple ways in which climate impinges on depositional systems, the orbital signals are recorded in a multiplicity of parameters, and affect different sedimentary facies in different ways. In platform carbonates, for example, the chief effect is via sea-level variations (possibly tied to fluctuating ice volume), resulting in cycles of emergence and submergence. In limnic systems it finds its most dramatic expression in alternations of lake and playa conditions. Biogenic pelagic oozes such as chalks and the limestones derived from them display variations in the carbonate supplied by planktonic organisms such as coccolithophores and foraminifera, and also record variations in the aeration of bottom waters. Whereas early studies of stratigraphic cyclicity relied mainly on bedding variations visible in the field, present studies are supplementing these with instrumental scans of geochemical, paleontological, and geophysical parameters which yield quantitative curves amenable to time-series analysis; such analysis is, however, limited by problems of distorted time-scales. My own work has been largely concentrated on pelagic systems. In these, the sensitivity of pelagic organisms to climatic-oceanic changes, combined with the sensitivity of botton life to changes in oxygen availability (commonly much more restricted in the Past than now) has left cyclic patterns related to orbital forcing. These systems are further attractive because (1) they tend to offer depositional continuity, and (2) presence of abundant microfossils yields close ties to geochronology. A tantalizing possibility that stratigraphy may yield a record of orbital signals unrelated to climate has turned up in magnetic studies of our Cretaceous core. Magnetic secular variations here carry a strong 39 ka periodicity, corresponding to the theoretical obliquity period of that time - Does the obliquity cycle perhaps have some direct influence on the magnetic field?

Fischer, Alfred G.

1992-01-01

157

Martian surface roughness and stratigraphy  

NASA Astrophysics Data System (ADS)

Orbital datasets can be combined and manipulated to learn about the three- dimensional structure of planetary surfaces, and the processes that have acted on them. The Mars Orbital Camera (MOC) is providing high-resolution images. These images allow qualitative inspection of features, and contain quantitative information about the shape of the surface. Using a photoclinometry technique derived from a lunar-Lambert photometric function, I am able to obtain estimates of the down-sun slope of each pixel in an image. This technique was calibrated against synthetic topography, compared to an area photoclinometry technique, and applied to the Viking and Pathfinder landing sites. It is a robust technique for obtaining the roughness and slope characteristics of large areas. It was applied to the potential landing sites for the Mars Exploration Rovers to evaluate site safety. The slopes from this point photoclinometry technique can be used to obtain a rough estimate of topography, which I used in a number of studies where topographic information was crucial. MOC images have shown that layering is pervasive on the martian surface. Mars Orbital Laser Altimeter (MOLA) data can be registered to MOC images to provide elevation constraints on layer outcrops. Such layers are observed in eastern Coprates Chasma both in the chasma rim and in a flat-topped massif. Observations indicate that the chasma stratigraphy consists of thin sequences of resistant layers and intervening thicker sequences of relatively less resistant layers. More resistant units cap the massif against erosion and result in steeper slopes than the weaker units would otherwise allow. These resistant layers can be used as stratigraphic markers which have allowed me to measure the subsidence and tilting of the massif relative to the chasma walls, providing evidence for tectonic motion in this portion of the Valles Marineris. These outcrops indicate that some of these layers may be analogus to terristrial flood basalts in both composition and extent. I have constrained the dip angle of finely layered sequences in Ganges and Hebes Mensae. These layers are either flat lying or dip shallowly, but do not dip steeply, which places some constraints on the origin of these mensae.

Beyer, Ross Alan

2004-12-01

158

Paleocene sequence stratigraphy of southwestern Alabama  

Microsoft Academic Search

In southwestern Alabama, the Paleocene consists of about 1300 ft (396 m) of marginal marine and marine terrigenous and carbonate sediments. Based on regional stratigraphic, sedimentologic, and paleontologic data, up to seven unconformity-bounded depositional sequences resulting from relative changes in coastal onlap during the Paleocene are recognized in these strata. These sequences are, in ascending order, the TP1.1a, comprised of

E. A. Mancini; B. H. Tew

1988-01-01

159

Age and Elevations of High-Level OIS2 Pluvial Lake Manly Shorelines, Northern and Central Death Valley: Implications for Lacustrine Sequence Stratigraphy in Southern Death Valley and the OIS6 Pluvial Lake Level  

NASA Astrophysics Data System (ADS)

New 14C ages of algal tufa from high-level Lake Manly shorelines at the Beatty Bar Complex (BBC) in Northern Death Valley (NDV) and on the west flank of the Black Mountains in Central Death Valley (CDV) indicate that shoreline features at elevations of up to 46 m and 61 m, respectively, formed during the latest- Pleistocene, OIS2 pluvial-lake cycle rather than the earlier OIS6 lake cycle as commonly interpreted. In-situ algal tufa clast coatings in the highest shoreline gravel bar at the BBC yielded an age of 26.97±0.62 14C kyrs B.P. The prominent horizon of tufa coatings lies ~1.5 m below the bar crest (46 m) and is interpreted to mark the static elevation of the OIS2 Lake Manly highstand. The tufa age is consistent with the gravel bar's youthful geomorphic expression and generally weak soil development, a previously reported TL age of 24.0±2.5 ka from fine-grained lagoonal(?) deposits behind this same gravel bar (45 m), a thinolitc-tufa age of 16.40-15.75 cal yrs B.P. from Mesquite Flat (37 m), and U-series ages (9.6±3.3 and 30.1±3.3 ka) and associated deep-lake ostracodes from core in CDV. In CDV, 2.5 km north of Badwater, prominent shoreline beach rock and algal tufa lie in deposition against the steep footwall escarpment of Black Mountains fault zone (BMFZ) to an elevation of ~61 m. Algal tufa collected at ~55 m yielded an age of 24.55±0.33 14C kyrs B.P. indicating that OIS2 Lake Manly highstand shorelines in CDV now lie at least 15 m higher than in NDV. The lack of major vertical-slip-rate faults in NDV suggests absolute footwall uplift adjacent to the prominent BMFZ (ala Borah Peak) may account for the difference. In Southern Death Valley (SDV), new mapping and tephra ages have defined a series of 3 lacustrine sequences well exposed along eastern traces of the Southern Death Valley fault zone (SDVFZ): 1) a lower sequence of highly-folded, late-Pliocene strata containing ~3.4 Ma Mesquite Springs tephra (correlative to strata in the eastern Noble Hills); 2) a gently- folded middle sequence of early-to-middle-Pleistocene strata containing Glass Mountain (1.2-0.9 Ma) and Lava Creek (0.64 Ma) tephra (age-correlative to strata in the Confidence Hills); and 3) a non-folded upper sequence, which is not dated, but clearly unconformably overlies the folded middle sequence. The upper sequence also shows only minor displacement along the SDVFZ. The upper sequence lies at a maximum elevation of ~45 m, the same as the BBC highstand gravel bar 100 km to the north. Hence, we correlate the undeformed upper lacustrine sequence in SDV to the OIS2 phase of Lake Manly. Although previously dated OIS6 shorelines (120-186 ka) along the Black Mountains escarpment lie at an elevation of ~90 m, we have yet to identify an OIS6 sequence of lacustrine deposits in SDV. Again, following the concept of absolute footwall uplift along the BMFZ, it is possible that the OIS6 Lake Manly highstand was considerably lower than 90 m and didn't spill into SDV. A relatively lower OIS6 lake level (<46 m OIS2) is consistent with our current understanding of the regional paleohydrology. During the OIS6 lake phase, the Amargosa River terminated in Lake Tecopa, and major flow into Death Valley was perhaps limited to spillover from the Owens-Searles- Panamint lake chain. During the OIS2 lake phase, both the Amargosa and Mojave rivers flowed into Death Valley.

Caskey, S.; Lackey, H. G.; Klinger, R. E.; Wan, E.; Sarna-Wojcicki, A.

2006-12-01

160

Mapping Stratigraphy and Anomalies in Iron-Rich Volcanoclastics Using Ground-Penetrating Radar: Potential for Subsurface Exploration on Mars  

Microsoft Academic Search

Ground-penetrating radar (GPR) studies conducted in iron-rich volcanoclastics can yield valuable information for interpreting the subsurface stratigraphy resulting from lava flows and intervening unconsolidated volcanic and sedimentary deposits with different compositions and ages. GPR is also valuable for mapping subsurface anomalies and structures, such as rifts and lava tubes. We performed a geophysical field survey in Craters of the Moon

E. Heggy; S. Clifford; S. Khan; J. Fernandez; E. Wiggs; S. L. Gonzalez; D. Wyrick; R. Grimm; C. Dinwiddie; A. Pommerol

2004-01-01

161

A revision of the structure and stratigraphy of pre-Green Tuff ignimbrites at Pantelleria (Strait of Sicily)  

E-print Network

1 A revision of the structure and stratigraphy of pre-Green Tuff ignimbrites at Pantelleria (Strait. In this paper we focus on the intermediate cycle of eruptive activity which is bracketed by ignimbrite units. This age interval (181 - 85 ka) was punctuated by six ignimbrite-forming eruptions (silicic and variably

Boyer, Edmond

162

Sequence stratigraphy and onlap history of the Donets Basin, Ukraine: Insight into Carboniferous icehouse dynamics  

Microsoft Academic Search

The degree to which Permo-Carboniferous cyclothemic successions archive evidence for long-term variations in ice volume during the Late Paleozoic Ice Age is insufficiently resolved. Here we develop the sequence stratigraphy and onlap–offlap history for a 33-my interval of the Carboniferous using the U–Pb calibrated succession of the Donets Basin, Ukraine, in order to assess the relationship between sea-level, high-latitude changes

J. M. Eros; I. P. Montañez; D. A. Osleger; V. I. Davydov; T. I. Nemyrovska; V. I. Poletaev; M. V. Zhykalyak

163

Process-sedimentological challenges in distinguishing paleo-tsunami deposits  

Microsoft Academic Search

There has been a lively debate since the 1980s on distinguishing between paleo-tsunami deposits and paleo-cyclone deposits\\u000a using sedimentological criteria. Tsunami waves not only cause erosion and deposition during inundation of coastlines in subaerial\\u000a environments, but also trigger backwash flows in submarine environments. These incoming waves and outgoing flows emplace sediment\\u000a in a wide range of environments, which include coastal

G. Shanmugam

164

Reverse engineering mother nature — Shale sedimentology from an experimental perspective  

NASA Astrophysics Data System (ADS)

Experimental study of the sedimentology of shales can take a variety of forms. At its simplest one can experiment with suspensions in a glass jar and try to understand their settling behavior, or one can manipulate mud in a tank or bucket to gain insights into its rheology. This approach was championed over a century ago by Sorby, and the insights gained can be quite profound. More recently, tank and settling tube experiments of animal-sediment interactions, compaction behavior, and sediment unmixing via re-suspension have proven to be highly informative in spite of their simplicity. Flumes can be used to obtain quantitative information about depositional and erosional parameters and to generate fundamental bedforms. In flume experiments, however, it is of critical importance that the flume be designed in a way that flocculated materials move under shear stress conditions that would be reasonable in natural environments. Although much flume work on muds has been conducted by hydraulic engineers, the transfer of that knowledge to sedimentology is hampered by the fact that engineers and sedimentologists are interested in different (though not mutually exclusive) products from such experiments. Engineers and hydrologists are commonly concerned with quantifying fluid flow properties, whereas sedimentogists are particularly interested in the sedimentary products that result from a variety of flow conditions. Recent sedimentologically oriented flume studies have shown that muds can form deposits at flow velocities and shear stresses that would suffice to transport and deposit medium grained sand. Mud suspensions are prone to flocculation and the resulting floccules travel in bedload and form ripples that accrete into beds. The latter finding suggests that many laminated shales were deposited from currents rather than by settling from slow moving or still water. There are many other sedimentary features in shales that can potentially be reproduced in flume studies and in the future serve to provide a quantitative basis for shale sedimentology.

Schieber, Juergen

2011-06-01

165

Reconstructing habitats in central Amazonia using megafauna, sedimentology, radiocarbon, and isotope analyses  

NASA Astrophysics Data System (ADS)

A paleomegafauna site from central Amazonia with exceptional preservation of mastodons and ground sloths allows for the first time a precise age control based on 14C analysis, which, together with sedimentological and ? 13C isotope data, provided the basis to discuss habitat evolution within the context of climate change during the past 15,000 yr. The fossil-bearing deposits, trapped within a depression in the Paleozoic basement, record three episodes of sedimentation formed on floodplains, with an intermediate unit recording a catastrophic deposition through debris flows, probably favored during fast floodings. The integrated approach presented herein supports a change in humidity in central Amazonia through the past 15,000 yr, with a shift from drier to arboreal savanna at 11,340 (±50) 14C yr B.P. and then to a dense forest like we see today at 4620 (±60) 14C yr B.P.

de Fátima Rossetti, Dilce; de Toledo, Peter Mann; Moraes-Santos, Heloísa Maria; de Araújo Santos, Antônio Emídio

2004-05-01

166

C. R. Geoscience 335 (2003) 681689 Stratigraphie  

E-print Network

C. R. Geoscience 335 (2003) 681­689 Stratigraphie Présence de Paléocène marin dans les Grands et al., C. R. Geoscience 335 (2003). 2003 Académie des sciences. Publié par �ditions scientifiques as the Rodez region. To cite this article: B. Peybernès et al., C. R. Geoscience 335 (2003). 2003 Académie des

Demouchy, Sylvie

167

Microfacies sedimentology of the Lower-Middle Kindblade Formation, Slick Hills, Southwestern Oklahoma.  

E-print Network

??MICROFACIES SEDIMENTOLOGY OF THE LOWER-MIDDLE KINDBLADE FORMATION (ORDOVICIAN), SLICK HILLS, SOUTHWESTERN OKLAHOMA In the late Cambrian (Franconian), a marine transgression took place on the Laurentian… (more)

Blair, Charles Grant

2013-01-01

168

Sequence stratigraphy and depositional systems of the Lower Silurian Medina Group, northern Appalachian basin  

SciTech Connect

Detailed sedimentological analysis of 3500 ft of continuous core from 44 wells in Pennsylvania, Ohio, Ontario, New York, and West Virginia, combined with regional study of geophysical logs, results in new interpretations of sequence stratigraphy and depositional systems in Lower Silurian siliciclastic rocks of the northern Appalachian basin. Above a type-1 sequence boundary at the base of the Medina Group are a lowstand systems tract and a transgressive systems tract that are represented, respectively, by the Whirlpool Sandstone and by the overlying Cabot Head Shale. The thickest sandstones in the Medina Group occur in the Grimsby Sandstone, which is interpreted as a highstand systems tract with basinward-prograding parasequences. Sea level rise after Grimsby parasequence deposition is represented by marine-shelf shale in the uppermost part of the Medina Group. Based on facies successions in the cores, four mappable depositional systems are interpreted for the Grimsby Sandstone and correlative sandstone units; (1) wave-dominated middle shelf, (2) wave- and tide-influenced inner shelf, (3) tide dominated shoreline, and (4) fluvial. The wave-dominated middle-shelf system, which includes very fine-grained shelf-ridge sandstones encased in marine shale, is the most basinward system, occurring from Ontario through parts of eastern Ohio. Shoreward, across the northern Appalachian basin, the influence of tidal processes relative to wave processes generally increased, which may have been related to distance across the shelf, water depth, and shoreline configuration. The shoreline may have been deltaic in some areas and straight in other areas.

Castle, J.W. (Cabot Oil and Gas Corp., Pittsburgh, PA (United States))

1991-08-01

169

Jurassic sequence stratigraphy of the eastern Gulf Coastal Plain: Applications to hydrocarbon exploration  

SciTech Connect

Based on regional stratigraphic and sedimentologic data, three unconformity-bounded depositional sequences associated with cycles of relative sea-level change and coastal onlap are recognized for Jurassic strata in the eastern Gulf Coastal Plain area. These sequences are designated, in ascending order, the LZAGC (Lower Zuni A Gulf Coast)-3.1, the LZAGC-4.1, and the LZAGC-4.2 sequences and include Callovian through Kimmeridgian Stage strata. An understanding of the relationship of Jurassic reservoirs to sequence stratigraphy can serve as an aid to hydrocarbon exploration in the eastern gulf area. The most extensive and productive Jurassic hydrocarbon reservoirs in the study area occur within the progradational, regressive highstand deposits of the LZAGC-3.1 and LZAGC-4.1 depositional sequences. For example, the majority of Norphlet sandstone reservoirs in the onshore and offshore Alabama area are interpreted to have accumulated in eolian dune, interdune, and wadi (fluvial) depositional environments, which occurred in association with the highstand regressive system of the LZAGC-3.1 sequence. The most important Smackover reservoirs generally consist of partially to completely dolomitized ooid and peloid packstones and grainstones in the upper portion of the unit. These reservoirs occur in subtidal to supratidal, shoaling-upward carbonate mudstone to grainstone cycles in the highstand regressive system of the LZAGC-4.1 sequence. In addition, minor reservoirs that are discontinuous and not well developed are associated with the shelf margin and transgressive systems of the LZAGC-4.1.

Tew, B.H.; Mancini, E.A.; Mink, R.M. (Geological Survey of Alabama, Tuscaloosa (United States))

1991-03-01

170

Sedimentology of the Paestum travertines, Salerno, Southern Italy  

NASA Astrophysics Data System (ADS)

The Paestum travertines, outcrop in the southern part of the Sele plain (Campania, southern Italy)and span in age from the late Pleistocene to the Recent. We have considered both the travertines resting under the ancient town of Paestum (founded by Sybaris Greeks in the VII century b.C.) and in its vicinities, as well as the travertine incrustations that post-date the VII century a.C. and partly cover the archaeological area. The textures and sedimentary features of the above rocks allow the environmental dynamics of the ancient as well as of the recent travertine deposits to be interpreted. The age of the ancient travertines ranges from 30-40 ka to 70-75 ka, even though more recent times of deposition cannot be excluded. They are genetically related to the waters springing from the south- western margin of the Mesozoic-Tertiary carbonates of Monte Soprano and Monte Sottano. These waters flow also through the travertines and their neighbouring deposits, feeding other springs along the coast. The travertines, both in situ and forming the building blocks of the town walls, have been classified using the textural nomenclature of the primary incrustations. On this basis, different lithofacies have been recognized and grouped into 3 main lithofacies associations: 1) Microhermal and Stromatolitic Travertines associated with Grain Supported Phytoclastic Travertines (gentle to steep slope environments); this lithofacies association is largely represented in the foundation travertines as well as in the blocks used to build the walls and the monuments of the ancient town; 2) Phytohermal and Microhermal Travertines (rapid and waterfall environments); this lithofacies association is well exposed in the foundation travertines of Porta Marina (western side of the town) and in some wall blocks (e.g. nearby Porta Sirena, eastern side of the town); 3) Phytoclastic and Phytohermal Travertines (swamp and marsh environments); this lithofacies association is common in the blocks forming the town wall between Porta Sirena and Porta Giustizia (southern-eastern side of Paestum) and in the civil and sacred architecture. The time-space relationships among the above lithofacies associations clearly emerge in the Porta Marina area both in the Greek walls of the ancient town (slope and swamp facies) and in the outcropping travertine substrate (slope and waterfall deposits). Based on the above sedimentological results, it may be inferred that, like other ambient temperature travertine systems studied in southern Italy, the Paestum travertine growth developed over a gentle slope surface (in our case dipping to the west), laterally evolving into rapid and waterfall deposits. At the same time, the aggradational growth of the travertine system resulted in a flattened summit area with widespread swamp and marsh environments. The ruins of Paestum, including the lower parts of sacred and civil buildings as well as town roads and walls, are even today largely covered by recent semi-coherent travertines (tufa), originating from waters that encrusted and then "fossilized" a large part of the town. Inside the town walls, these materials were pedogenized and nowadays are largely cultivated around and within the archeological area. A portion of these deposits was removed during the excavations of the beginning of last century, but traces of them may still be observed in different parts of the ancient town. Like the foundation travertines, the recent deposits are mainly made up of calcareous encrustations. Gastropods, ostracods and other organisms typical of terrestrial humid environments may be found in the phytoclastic textures. Usually, they are weakly cemented and at places incorporate different materials, including brick, wood and coal fragments. These sediments patchy cover the town within the wall perimeter, for a few decimetres in the sacred areas, but reaching over 4 meters downhill and outside the walls: a process of "fossilization" that appears to have been particularly effective at Porta Marina, on the sea side of Paestum, where the

Anzalone, E.; Ferreri, V.; D'Argenio, B.

2009-04-01

171

Latest Carboniferous–earliest Permian transgressive deposits in the Paganzo Basin of western Argentina: Lithofacies and sequence stratigraphy of a coastal-plain to bay succession  

Microsoft Academic Search

The upper Paleozoic rocks of Gondwana record a complex paleoclimatic history related to the migration of the supercontinent over high latitudes. Changes in climate and relative sea level can be traced through detailed sedimentologic and sequence-stratigraphic analysis. Our study focuses on transgressive deposits of Stephanian–Early Permian age in the lower member of the Tupe Formation with the objective of characterizing

Patricio R. Desjardins; Luis A. Buatois; Carlos O. Limarino; Gabriela A. Cisterna

2009-01-01

172

GEOBULLETIN GeoBulletin is distributed weekly, by E-mail. Contributions are requested!  

E-print Network

in sedimentology and stratigraphy, and geological mapping. Currently I am studying geology for the academic year interested in sedimentology and stratigraphy at Miami and have since taken additional courses at Trinity including sedimentology and stratigraphy, sedimentary petrology, and paleontology, paleoecology

Carlson, Anders

173

Sequence stratigraphy of paralic coal-bearing strata: an overview  

Microsoft Academic Search

Sequence stratigraphy arose in the late 1980s to fundamentally change the science of stratigraphy. Former practice of labeling formations and erecting stratigraphic columns gave place to a dynamic genetic stratigraphic analysis, where the main concern is about understanding the history of sedimentation and to establish models able to predict facies. Born and mainly applied to an environment of petroleum prospecting

Michael Holz; Wolfgang Kalkreuth; Indranil Banerjee

2002-01-01

174

Structural geology and sedimentology of the Heiligenhafen till section, Northern Germany  

NASA Astrophysics Data System (ADS)

Three Pleistocene tills can be distinguished in a coastal cliff section near Heiligenhafen, northern Germany, on the basis of structural and petrographic characteristics. The Lower and Middle Tills had previously been ascribed to the Saalian, and the Upper Till to the Late Weichselian. The former two tills are folded, and unconformably overlain by the Upper Till. In this paper, structural and sedimentological observations are used to investigate whether the Lower and Middle Tills belong to one glacial advance, or two separate (Saalian) advances, as was suggested in earlier studies based on fine gravel stratigraphy. From the contact with local rocks to the top of the MT there is a steady increase in allochtonous components (Scandinavian rocks) and decrease in parautochtonous (chalk and flint) and autochtonous components (local Eocene siltstone and meltwater sediments). This is paralleled by a trend towards increasing deformation (finite strain) from the bedrock to the top of the section. The most obvious aspect of this latter trend is the massive appearance of the MT which can be interpreted as the result of homogenization by repeated folding and attenuation of sediment lenses which have been incorporated into the till. This interpretation is supported by macroscopic and microscopic observations of structures in both tills. The structural analysis of the tills is based on the marked contrast in symmetry between sections parallel and perpendicular to the shear direction. Structures on all scales in the LT as well as in the MT indicate E-W (dextral) shearing, except in the western part of the section, where this is overprinted by W-E (sinistral) shearing. The sediment inclusions in the chalk-rich LT are mainly fragments of one or more strongly extended glaciofluvial delta bodies with a depositional direction towards WSW. Locally these delta sediments rest on Eocene siltstone and contain numerous angular fragments of this local bedrock. Boudins and lenses of sorted sediments are incorporated into the till and occur as "islands of low strain" in a high strain homogeneous matrix. It is concluded that the LT and MT do not belong to two stratigraphically separate Saalian advances. The section is alternatively interpreted as one subglacial shear zone (deformation till) with upward increasing strain and allochtonous component content. It probably formed during the Younger Saalian (Warthe) westward advance from the Baltic region. Folding of the two diamicts occurred due to lateral compression near the Late Saalian ice margin. The section was finally overridden by the Late Weichselian Young Baltic advance, eroding the folded LT and MT and depositing the UT.

Van der Wateren, Frederik M.

1999-12-01

175

Part I of Manuscript submitted to Sedimentology, May, 2006 Unraveling the conundrum of river response to rising sea level  

E-print Network

Part I of Manuscript submitted to Sedimentology, May, 2006 1 Unraveling the conundrum of river of Manuscript submitted to Sedimentology, May, 2006 2 Fly-Strickland River system, Papua New Guinea to Holocene of Manuscript submitted to Sedimentology, May, 2006 3 Mississippi River was able to resist drowning due to sea

Parker, Gary

176

Part II of manuscript submitted to Sedimentology, May, 2006 Unraveling the conundrum of river response to rising sea level from  

E-print Network

Part II of manuscript submitted to Sedimentology, May, 2006 1 Unraveling the conundrum of river to Sedimentology, May, 2006 2 deltas is adapted to describe the response of the Fly-Strickland River system, Papua of manuscript submitted to Sedimentology, May, 2006 3 Pleistocene-Holocene eustatic sea level rise of some 120 m

Parker, Gary

177

Late-Quaternary morpho-sedimentology and submarine mass movements of the Betsiamites area, Lower St. Lawrence Estuary, Quebec, Canada  

E-print Network

Late-Quaternary morpho-sedimentology and submarine mass movements of the Betsiamites area, Lower St 2008 Accepted 4 March 2008 Keywords: submarine mass movements morpho-sedimentology multibeam bathymetry the submarine morpho-sedimentology of an area of 500 km2 with focus on the consequences of four mass movement

St-Ong, Guillaume

178

Sedimentology of Seismo-Turbidites off the Cascadia and Northern California Active Tectonic Continental Margins, Northwest Pacific Ocean  

E-print Network

Ã?Ã? Ã? Ã?Ã?Ã? Ã? Ã?Ã? Sedimentology of Seismo-Turbidites off the Cascadia and Northern California Active, Goldfinger, Chris, Escutia, Carlota, Sedimentology of Seismo-Turbidites off the Cascadia and Northern Cal ACCEPTED MANUSCRIPT 1 Sedimentology of Seismo-Turbidites off the Cascadia and Northern California Active

Goldfinger, Chris

179

Carboniferous stratigraphy of the Appalachians  

SciTech Connect

Carboniferous rocks in the Appalachian fold-thrust belt and foreland basins include parts of four clastic wedges. Distribution, composition, and ages of the clastic wedges record diachronous orogenic uplifts along the Appalachian margin. Lower Mississippian Pocono sandstones form the upper part of the Catskill-Pocono clastic wedge, which includes the Devonian Catskill deltaic facies. Pocono rocks reflect clastic sediments transport toward the northwest and west from an orogenic source east of the Pennsylvania salient. The upper Mississippian-Pennsylvanian Mauch Chunk-Pottsville clastic wedge prograded westward and southwestward from the Pennsylvania salient over Mississippian limestone. The southwestern limit of the Mauch Chunk-Pottsville clastic wedge is overlapped in the Virginia recess by the oppositely directed Pennington-Lee clastic wedge. The Upper Mississippian-Pennsylvanian Pennington-Lee clastic wedge prograded northeastward and northwestward from the Tennessee salient. Southwestward in the Alabama recess, the Pennington clastic facies grades into Mississippian limestone, and Lee-equivalent sandstones extend over the limestone. In the western part of the Alabama recess, Upper Mississippian-Lower Pennsylvanian delta systems prograded northeastward over the Mississippian carbonate facies. These clastic sediments are an eastern shelf-delta part of a thick clastic wedge that consists of turbidites in the Ouachita salient. The eastern fringe of the Ouachita clastic wedge merges with the southwestward-prograding Pennington-Lee clastic wedge above Mississippian carbonate rocks in the Alabama recess.

Hines, R.A.; Thomas, W.A.

1985-01-01

180

Probable age of Autolycus and calibration of lunar stratigraphy  

NASA Astrophysics Data System (ADS)

Ar-39 - Ar-40 analyses of three petrographically distinct, shocked Apollo 15 KREEP (i.e., high K, rare earth element, P, and other trace element contents) basalt samples demonstrate that a major impact event affected all three samples at about 2.1 Ga. The Copernican System craters Aristillus and Autolycus are to the north. Autolycus, the older of the two, is in a particularly appropriate terrain and is the most likely source of the 2.1 Ga heating and delivery event. With this calibration point, and if Autolycus really is a Copernican crater, the Copernican System lasted twice as long as has previously been suggested. Furthermore, the moon was not subjected to a constant cratering rate over the past 3 billion years; the average rate in the preceding Eratosthenian must have been twice that in the Copernican.

Ryder, G.; Bogard, D.; Garrison, D.

1991-02-01

181

Time-stratigraphic reconstruction and integration of paleopedologic, sedimentologic, and biotic events (Willwood Formation, lower Eocene, northwest Wyoming, USA)  

SciTech Connect

Relative paleosol maturities are inversely proportional to the accumulation rates of the sediment upon which they formed, and are therefore excellent relative indicators of how much geologic time elapsed between any two horizons. An empirically-based model is advanced using paleosol maturities to estimate the relative geologic time separating any stratigraphic levels within the lower Eocene Willwood Formation. The revised Willwood time stratigraphy from this analysis helps evaluate the nature, tempo, and possible causes of three major episodes of mammalian appearance and disappearance. These faunal events are directly correlated with certain aspects of paleosol evolution in the Willwood Formation. That evolution is tied directly to climatic changes and to varying sediment accumulation rates in response to tectonism. The first faunal turnover occurs at the base of the Willwood Formation. It coincides with a major increase in pedogenic maturity, reflecting a major decrease in sediment accumulation rate, and accompanying general climatic warming at about the time of the Paleocene-Eocene boundary. Throughout the remainder of Willwood time, there was a gradual, yet continual, decrease in paleosol maturity and degree of hydromorphy, probably related to the progressive structural elevation of the Owl Creek antiform bounding the south and southeast margins of the Bighorn Basin. This gradual decrease was punctuated by two intervals of more significant decline in paleosol maturity and in the incidence of hydromorphic soils. Both intervals are also marked by faunal turnovers. These sedimentologic and biologic events may reflect tectonic, periods when the rate of basin subsidence increased more rapidly. 58 refs., 7 figs., 2 tabs.

Brown, T.M. (Geological Survey, Denver, CO (United States)); Kraus, M.J. (Univ. of Colorado, Boulder (United States))

1993-02-01

182

Carbon isotope stratigraphy of an ancient (Ordovician) Bahamian-type carbonate platform: Implications for preservation of global seawater trends  

NASA Astrophysics Data System (ADS)

Carbon isotope stratigraphy has a unique role in the interpretation of Earth history as one of the few geochemical proxies that have been widely applied throughout the geologic time scale, from the Precambrian to the Recent, as both a global correlation tool and proxy for the carbon cycle. However, in addition to consideration of the role of diagenesis, numerous studies have raised awareness of the fact that C-isotope trends derived from ancient carbonate platforms may not be representative of dissolved inorganic carbon from a well-mixed global ocean reservoir. Furthermore, the larger carbon isotopic fractionation in the formation of aragonite versus calcite from seawater must be taken into account. All three of these variables (diagenesis, water mass residence time, % aragonite) may change in response to sea level, producing trends in C-isotopes on ancient carbonate platforms that are unrelated to the global carbon cycle. Global carbon cycle fluxes may also have a cause-effect relationship with sea level changes, further complicating interpretations of stratigraphic trends in carbon isotopes from ancient platform environments. Studies of C-isotopes in modern carbonate platform settings such as the Great Bahama Bank (GBB) provide important analogues in addressing whether or not ancient platforms are likely to preserve a record of carbon cycling in the global ocean. Swart et al. (2009) found that waters of the GBB had generally the same or elevated values (ranging from +0.5‰ to +2.5‰) compared to the global oceans, interpreted as reflecting differential photosynthetic fractionation and precipitation of calcium carbonate (which lowers pH and converts bicarbonate into 12-C enriched carbon dioxide, leaving residual bicarbonate heavier). Carbonate sediments of the GBB have elevated C-isotopes, not only because of the high C-isotope composition of the overlying waters, but also due to the greater fractionation associated with precipitation of aragonite versus calcite. Few studies of ancient carbonates have attempted to explicitly compare C-isotope trends in both restricted platform settings and open marine settings (e.g., Immenhauser et al. 2002). We studied a restricted Bahamian-type carbonate platform of Middle-Late Ordovician (Darriwilian-early Sandbian) age included in the St. Paul Group of Maryland, notable for sedimentologic evidence of severe restriction and a general lack of open marine macrofauna. We are able to correlate the C-isotope curve from the St. Paul Group to other sections globally by using a combination of conodont microfossils and measurement of Sr isotopes on conodont apatite. Coeval C-isotope trends from open marine settings in the western United States and Estonia are comparable to the restricted platform in Maryland. In our Ordovician example, local factors appear to have modified the magnitude of the global trends, but not the timing and direction. A remaining question is whether magnitude differences are a function of sedimentation rate and completeness. We continue to test hypotheses of global correlations of C-isotope trends in the Middle-Late Ordovician by utilizing the rapidly changing Sr isotope curve at that time.

Saltzman, M.; Leslie, S. A.; Edwards, C. T.; Diamond, C. W.; Trigg, C. R.; Sedlacek, A. R.

2013-12-01

183

Fluvial responses to climate and sea-level change: a review and look forward  

E-print Network

stratigraphic, sedimentological and geochronological frameworks in a variety of continental interior sedimentology, Quaternary geology, sea-level change, sequence stratigraphy. Sedimentology (2000), 47 (Suppl. 1

Törnqvist, Torbjörn E.

184

Review and Comparison of Belly River Group and Edmonton Group Stratigraphy and Stratigraphic Architecture in the Southern Alberta Plains  

Microsoft Academic Search

The region of southern Alberta south of T35 and east of W5 contains laterally extensive-to-patchy exposures and subsurface strata of the Campanian- Maastrichtian age Belly River and Edmonton Groups. During the past 10 years the stratigraphy of the Belly River Group in this region has been re-interpreted and redefined using a sequence and event stratigraphic approach. More recently, portions of

David A. Eberth

185

Stratigraphy and Tectonic Evolution of Nefertiti Corona on Venus  

NASA Astrophysics Data System (ADS)

Study of corona Nefertiti stratigraphy and deformation structures lead to suggestion a scenario of its multistage evolution, including rejuvenation. Part of corona annulus is interpreted to be a landslide.

Krassilnikov, A. S.

1999-03-01

186

Stratigraphy and dissolution of the Rustler Formation  

SciTech Connect

The Rustler Formation is the uppermost evaporite-bearing unit in the Permian Ochoan series in southeastern New Mexico. It rests on the Salado Formation which includes the salt beds where the mined facility for the Waste Isolation Pilot Plant (WIPP) is being constructed. An understanding of the physical stratigraphy of the Rustler Formation is pertinent to studies of the WIPP site because some portions of the Rustler are water-bearing and may provide paths for circulating waters to come into contact with, and dissolve, evaporites within the Ochoan sequence. Knowledge of the processes, magnitude, and history of evaporite dissolution in the vicinity of the WIPP site is important to an evaluation of the integrity of the site. 2 refs., 2 figs.

Bachman, G.O.

1985-04-23

187

The stratigraphy of the Jackson Group, Grimes County, Texas  

E-print Network

THE STRATIGRAPHY OF THE JACKSON GROUP, GRIHES COUNTY, TEXAS A Thesis RANDALL NEAL EICHER Submitted to the Graduate College, of Texas ASH University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1985... Hajor Subject: Geology THE STRATIGRAPHY OF THE JACKSON GROUP, GRINES COUNTY, TEXAS A Thesis by RANDALL NEAL EICHER Approved as to style and content by: hristop r . Mathewson (Chai rman o mm'ttee ) nne aymo (Member ) arl oenig (Me ber) Earl R...

Eicher, Randall Neal

2012-06-07

188

Late Quaternary geotechnical stratigraphy of North Texas continental shelf  

E-print Network

LATE QUATERNARY GEOTECHNICAL STRATIGRAPHY OF NORTH TEXAS CONTINENTAL SHELF A Thesis by JOHN SAL MUNSEY Submitted to the Graduate College of Texas Algi University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE... December 1985 Major Subject: Geology LATE QUATERNARY GEOTECHNICAL STRATIGRAPHY OF NORTH TEXAS CONTINENTAL SHELF A Thesis by JOHN SAL MUNSEY Approved as to style and content by: br' sto er . Mathewson (Cha&r of Committee) Norman R . ' ord (Memb...

Munsey, John Sal

2012-06-07

189

Acquisition, 3-D display and interpretation of GPR data in fluvial sedimentology.  

E-print Network

??Alluvial architecture has an inherently three-dimensional character; however, standard methods used within fluvial sedimentology, including ground penetrating radar (GPR) surveys, generally provide only 1-D or… (more)

Zuk, Tomasz

2011-01-01

190

Sequential stratigraphy of Jurassic and Cretaceous in the central Saudi Arabian platform  

SciTech Connect

Depositional sequences and system tracts in the Jurassic and Cretaceous sedimentary rocks of the Central Saudi Arabian platform have been established on the basis of precise lithofacies analysis, detailed sedimentologic interpretation, and accurate age determination by ammonites, nautoli, brachipods, echinoids, and nannoflora. A eustatic depositional model integrated with accepted worldwide sequential stratigraphic data is proposed, and appears to correlate fairly well with the 1988 global sea level chart by Haq and others, particularly for the Lower and Middle Jurassic and the Middle and Upper Cretaceous. Ages determined by accurate biostratigraphic data enable time correlations to be made with third-order eustatic cycles from Vail's 1988 global chart. Eustatic changes therefore appear to be the main factors of sedimentary control during the Jurassic and Cretaceous on the Arabian platform.

Le Nindre, Y.M.; Manivit, J.; Vaslet, D. (Bureau de Recherches Geologiques et Minieres, Orleans (France)); Manivit, H. (Bureau de Recherches Geologiques et Minieres, Orleans (France) Univ. Pierre et Marie Curie, Paris (France))

1991-08-01

191

Impact of water resource development on the hydrology and sedimentology of the Brazos River system  

E-print Network

IMPACT OF WATER RESOURCE DEVELOPMENT ON THE HYDROLOGY AND SEDIMENTOLOGY OF THE BRAZOS RIVER SYSTEM A Thesis by Submitted to the Graduate College of Texas ALM University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE August 1976 Major Subject: Geology IMPACT OF WATER RESOURCE DEVFLOPMENT ON THE HYDROLOGY AND SEDIMENTOLOGY OF THE BRAZOS RIVER SYSTEM A Thesis by LARRY LANE MINTER Approved as to style snd. content by: (Chairman of Committee) n (Head...

Minter, Larry Lane

2012-06-07

192

Sedimentology and geochemistry of a mid-Proterozoic lacustrine unit from northern Australia  

NASA Astrophysics Data System (ADS)

The Wollogorang Formation is an unmetamorphosed middle Proterozoic sedimentary unit (ca. 100 m thick) in the highly mineralized McArthur Basin of northern Australia. Based on sedimentology three of the six lithofacies in this unit can be confidently interpreted to be of continental origin-facies 1: evaporitic red beds, deposited in highly saline mudflats on an irregular volcanic landsurface at the base of the formation; facies 3: varved organic-rich black shales deposited in a quiet water distal lacustrine setting in the middle of the formation; and facies 5: conglomeratic cross-bedded poorly sorted dolomitic sandstones deposited in braided fluvial environments near the top of the formation. A detailed geochemical study, mainly of facies 3, was carried out to see if the two studies would complement each other and to show what geochemical criteria may be useful in defining Proterozoic depositional environments. Dolomite concretions, which are present in the carbonate-poor black shales of facies 3, are shown to be early diagenetic. The 87Sr/ 86Sr ratio from one of these concretions is 0.7139, significantly above the accepted range for marine carbonates of this age (0.705-0.708). These concretions and surrounding black shales often contain relatively high pyrite contents. The concretions have ? 13C values similar to the average host dolomite value of -0.6%, and pyrite ? 34 values range from -3.5 to + 5.8% c (av. + 2.4%0). These data agree with the sedimentology and indicate a low sulfate lacustrine environment with little activity from the sulfate reducing bacteria. Disseminated pyrite ? 34S values from facies 2 and 4 (up to +11.8%0) suggest similar low sulfate environments: this combined with carbonate ? 18O values of around +23% facies 1-4 suggests there was only one water source present during deposition, diagenesis and lithification. When these data are viewed in the light of the regional stratigraphic setting and the gradational facies relationships they suggest a non-marine setting for the bulk of the Wollogorang Formation and support previous observations of an abundance of rift-related continental environments in this highly mineralized region. The relatively high pyrite S/organic C ratios found during this study are interpreted as indicating some addition of hydrothermally formed pyrite. This result is similar to that found in the black shales from the younger more highly mineralized rocks of the McArthur Basin and may support the originally perceived mineral ootential of units such as the Wollogorang Formation (Jackson, 1981a).

Donnelly, Terrence Henry; Jackson, Michael James

1988-08-01

193

Sedimentology and origin of source rocks in the Tertiary Niger delta  

SciTech Connect

Organic matter in Tertiary strata of the Niger delta is mainly a mixture of types II and III, has a high pristane/phytane ratio (> 1.0), and is composed of the macerals vitrinite and minor liptinite. The main palynofacies are structured woody material, cuticles, pollen, spores, and opaque and minor amorphous organic matter. The distribution and abundance of the organic matter reflects the age and sedimentology of the strata. There is a progressive decline in mean total organic carbon (TOC) content from upper Eocene (2.2% TOC) to Pliocene strata (0.90% TOC) and an associated general decrease in hydrogen index (HI) and pristane/phytane ratio. The decrease in TOC and HI in younger strata mainly reflects increased dilution of a nearly constant supply of terrestrial organic matter associated with the generally higher sedimentation rates of younger strata. The low pristane/phytane ratio of younger strata may reflect less oxidizing depositional conditions. No rich source rocks occur in the Niger delta and, as conventionally measured, the strata have little or no oil generating potential. The poor quality of the source rocks has been compensated for by their greater volume and excellent migration routes. The Niger delta type of source rock - although an end member in terms of general source rock composition - appears to be relatively typical of Tertiary deltas.

Bustin, R.M.

1988-08-01

194

50 years of snow stratigraphy observations  

NASA Astrophysics Data System (ADS)

With start in autumn 1961 the Abisko Scientific Research Station (ASRS) located in the Swedish sub Arctic has performed snow stratigraphy observations, resulting in a unique 50 year long time series of data. The data set contains grain size, snow layer hardness, grain compactness and snow layer dryness, observed every second week during the winter season. In general snow and snow cover are important factors for the global radiation budget, and the earth's climate. On a more local scale the layered snowpack creates a relatively mild microclimate for Arctic plants and animals, and it also determines the water content of the snowpack (snow water equivalent) important for e.g. hydrological applications. Analysis of the snow stratigraphy data, divided into three consecutive time periods, show that there has been a change in the last time period. The variable most affected is the snow layer hardness, which shows an increase in hardness of the snowpack. The number of observations with a very hard snow layer/ice at ground level increased three-fold between the first two time periods and the last time period. The thickness of the bottom layer in the snowpack is also highly affected. There has been a 60% increase in layers thinner than 10 cm in the last time period, resulting in a mean reduction in the thickness of the bottom layer from 14 cm to 11 cm. Hence the living conditions for plants and animals at the ground surface have been highly changed. The changes in the snowpack are correlated to an increased mean winter air temperature. Thus, continued increasing, or temperatures within the same ranges as in the last time period, is likely to create harder snow condition in the future. These changes are likely to affect animals that live under the snow such as lemmings and voles or animals that graze sub-Arctic vegetation in winter (e.g. reindeer that would potentially require increased supplementary feeding that incurs financial costs to Sami reindeer herders). Any decrease in lemmings and vole populations is likely to have cascading effects on biodiversity, particularly predators such as arctic foxes and snowy owls.

Johansson, C.; Pohjola, V.; Jonasson, C.; Challagan, T. V.

2012-04-01

195

Sediment transport processes and their resulting stratigraphy: informing science and society  

NASA Astrophysics Data System (ADS)

Sediment transport physically shapes planetary surfaces by producing patterns of erosion and deposition, with the relative magnitudes of geomorphic actions varying according to environmental conditions. Where sediment fills accommodation space and generates accumulation, a stratigraphic archive develops that potentially harbors a trove of information documenting dynamic conditions during the periods of sediment production, transport and deposition. By investigating the stratigraphic record, it is possible to describe changes in surface environments, as well as hypothesize about the development of regional tectonic and climate regimes. Ultimately, information contained within the stratigraphic record is critical for evaluating the geological history of terrestrial planets. The enigma of stratigraphy, however, is that sediment deposition is finicky, there is no uninterrupted record, and while deposits may reflect only a brief temporal window, they may still be used to infer about conditions that encompass much longer periods of time. Consider a case where meter-scale dune foresets, deposited in a matter of minutes to hours, are in contact with sediments above and below that reflect entirely different depositional circumstances and are separated in time by a hiatus of thousands or perhaps millions of years. To effectively unlock the scientific trove bound in stratigraphy, it is first necessary to identify where such unconformities exist and the conditions that lead to their development. This challenge is made much simpler through scientific advances in understanding sediment transport processes -- the examination of how fluid and solids interact under modern conditions -- because this is precisely where sediment patterns first emerge to produce accumulation that builds a stratigraphic record. By advancing an understanding of process-based sedimentology, it is possible to enhance diagnostic evaluations of the stratigraphic record. Fortunately, over the past several decades, there have been numerous scientific advances pertaining to the coupling of sediment transport and hydrodynamics. This research has produced new theory about how sediments accumulating in many unique environments shape the stratigraphic record. Recent studies have taken advantage of novel methods for acquiring observational data, which in turn have been used to advance numerical modeling schemes as well as experimental designs. As an example, consider fluvial deltas: here, hydrodynamics are constantly evolving over space and time. Patterns of sediment deposition and erosion (from dune to delta-lobe scales), resolved using high-resolution 3-D acoustic data, are used as input data to construct models that further show how channel dynamics (e.g., avulsions) and kinematics (e.g., lateral migration) evolve due to sediment and hydrodynamic coupling. This information is used to propose new theories of delta stratigraphy, which are then tested by examining ancient fluvial-delta systems. Finally, research efforts evaluating modern sediment-transport and depositional processes offer significant benefits to society. For example, fluvial deltas are heavily relied upon for societal welfare and yet are among the most dynamic landscapes on Earth's surface. Therefore, research examining the evolution of these landscapes not only advances basic science, but also doubles as an exercise in applied geomorphology.

Nittrouer, J. A.

2013-12-01

196

Stratigraphy and Leonardian F'usulinid Paleontology in Central Pequop Mountains,  

E-print Network

Stratigraphy and Leonardian F'usulinid Paleontology in Central Pequop Mountains, Elko County ......................Systematic paleontology 110 General statement ............................ 110 ..............Genus

Seamons, Kent E.

197

Geomorphology, facies architecture, and high-resolution, non-marine sequence stratigraphy in avulsion deposits, Cumberland Marshes, Saskatchewan  

NASA Astrophysics Data System (ADS)

This paper demonstrates field relationships between landforms, facies, and high-resolution sequences in avulsion deposits. It defines the building blocks of a prograding avulsion sequence from a high-resolution sequence stratigraphy perspective, proposes concepts in non-marine sequence stratigraphy and flood basin evolution, and defines the continental equivalent to a parasequence. The geomorphic features investigated include a distributary channel and its levee, the Stage I crevasse splay of Smith et al. (Sedimentology, vol. 36 (1989) 1), and the local backswamp. Levees and splays have been poorly studied in the past, and three-dimensional (3D) studies are rare. In this study, stratigraphy is defined from the finest scale upward and facies are mapped in 3D. Genetically related successions are identified by defining a hierarchy of bounding surfaces. The genesis, architecture, geometry, and connectivity of facies are explored in 3D. The approach used here reveals that avulsion deposits are comparable in process, landform, facies, bounding surfaces, and scale to interdistributary bayfill, i.e. delta lobe deposits. Even a simple Stage I splay is a complex landform, composed of several geomorphic components, several facies and many depositional events. As in bayfill, an alluvial ridge forms as the feeder crevasse and its levees advance basinward through their own distributary mouth bar deposits to form a Stage I splay. This produces a shoestring-shaped concentration of disconnected sandbodies that is flanked by wings of heterolithic strata, that join beneath the terminal mouth bar. The proposed results challenge current paradigms. Defining a crevasse splay as a discrete sandbody potentially ignores 70% of the landform's volume. An individual sandbody is likely only a small part of a crevasse splay complex. The thickest sandbody is a terminal, channel associated feature, not a sheet that thins in the direction of propagation. The three stage model of splay evolution proposed by Smith et al. (Sedimentology, vol. 36 (1989) 1) is revised to include facies and geometries consistent with a bayfill model. By analogy with delta lobes, the avulsion sequence is a parasequence, provided that its definition is modified to be independent from sea level. In non-marine settings, facies contacts at the tops of regional peats, coals, and paleosols are analogous to marine flooding surfaces. A parasequence is redefined here as a relatively conformable succession of genetically related strata or landforms that is bounded by regional flooding surfaces or their correlative surfaces. This broader definition incorporates the concept of landscape evolution between regional flooding surfaces in a variety of depositional settings. With respect to landscape evolution, accommodation space has three spatial dimensions — vertical ( x), lateral ( y), and down-the-basin ( z). A flood basin fills in as landforms vertically ( x) and laterally accrete ( y), and prograde down-the-basin ( z). Vertical aggradation is limited by the elevation of maximum flood stage (local base level). Differential tectonism and geomorphology control the slope of the flood basin floor and the direction of landscape evolution. These processes produce parasequences that include inclined stratal surfaces and oriented, stacked macroforms (clinoforms) that show the magnitude and direction of landscape evolution.

Farrell, K. M.

2001-02-01

198

Geomorphology, facies architecture, and high-resolution, non-marine sequence stratigraphy in avulsion deposits, Cumberland Marshes, Saskatchewan  

USGS Publications Warehouse

This paper demonstrates field relationships between landforms, facies, and high-resolution sequences in avulsion deposits. It defines the building blocks of a prograding avulsion sequence from a high-resolution sequence stratigraphy perspective, proposes concepts in non-marine sequence stratigraphy and flood basin evolution, and defines the continental equivalent to a parasequence. The geomorphic features investigated include a distributary channel and its levee, the Stage I crevasse splay of Smith et al. (Sedimentology, vol. 36 (1989) 1), and the local backswamp. Levees and splays have been poorly studied in the past, and three-dimensional (3D) studies are rare. In this study, stratigraphy is defined from the finest scale upward and facies are mapped in 3D. Genetically related successions are identified by defining a hierarchy of bounding surfaces. The genesis, architecture, geometry, and connectivity of facies are explored in 3D. The approach used here reveals that avulsion deposits are comparable in process, landform, facies, bounding surfaces, and scale to interdistributary bayfill, i.e. delta lobe deposits. Even a simple Stage I splay is a complex landform, composed of several geomorphic components, several facies and many depositional events. As in bayfill, an alluvial ridge forms as the feeder crevasse and its levees advance basinward through their own distributary mouth bar deposits to form a Stage I splay. This produces a shoestring-shaped concentration of disconnected sandbodies that is flanked by wings of heterolithic strata, that join beneath the terminal mouth bar. The proposed results challenge current paradigms. Defining a crevasse splay as a discrete sandbody potentially ignores 70% of the landform's volume. An individual sandbody is likely only a small part of a crevasse splay complex. The thickest sandbody is a terminal, channel associated feature, not a sheet that thins in the direction of propagation. The three stage model of splay evolution proposed by Smith et al. (Sedimentology, vol. 36 (1989) 1) is revised to include facies and geometries consistent with a bayfill model. By analogy with delta lobes, the avulsion sequence is a parasequence, provided that its definition is modified to be independent from sea level. In non-marine settings, facies contacts at the tops of regional peats, coals, and paleosols are analogous to marine flooding surfaces. A parasequence is redefined here as a relatively conformable succession of genetically related strata or landforms that is bounded by regional flooding surfaces or their correlative surfaces. This broader definition incorporates the concept of landscape evolution between regional flooding surfaces in a variety of depositional settings. With respect to landscape evolution, accommodation space has three spatial dimensions - vertical (x), lateral (y), and down-the-basin (z). A flood basin fills in as landforms vertically (x) and laterally accrete (y), and prograde down-the-basin (z). Vertical aggradation is limited by the elevation of maximum flood stage (local base level). Differential tectonism and geomorphology control the slope of the flood basin floor and the direction of landscape evolution. These processes produce parasequences that include inclined stratal surfaces and oriented, stacked macroforms (clinoforms) that show the magnitude and direction of landscape evolution. ?? 2001 Elsevier Science B.V. All rights reserved.

Farrell, K.M.

2001-01-01

199

Eolian event stratigraphy - A conceptual framework  

SciTech Connect

A basis for eolian event stratigraphy is to distill the impact of events into fundamental processes and products. For accumulation (net deposit through time) to occur, the sediment budget must be positive. If the sediment budget becomes neutral or negative, accumulation ceases and a bypass or erosional super bounding surface, respectively, forms capping the genetic unit. Within the three types of eolian systems (dry, wet, stabilized), the mechanisms of accumulation and super-surface formation differ. In the dry system, accumulation occurs because of areal deceleration of sand-carrying winds. Because of dune-interdune flow conditions, accumulation begins when interdune flats are closed, requiring sand supply, time, and conditions for dune growth at the expense of interdune flats. In the wet system, accumulation of dune and interdune deposits occurs by trapping with a rising water table. Accumulations vary with the nature of the water table rise, proportion of dunes and interdune flats, and interdune topography. In the stabilized system, accumulation occurs with rapid stabilization of elements of active eolian systems; super surfaces form when the causes of stabilization cease. The eolian rock record consists of preserved accumulations and super surfaces. Accumulation space is distinct from preservation space. Preservation space is made by subsidence and water table rise. Without preservation space, an unconformity results. The dominance of subsidence versus water table rise is reflected in dry and wet accumulations respectively, such as the Jurassic Navajo and Entrada sandstones.

Kocurek, G.; Havholm, K.G. (Univ. of Texas, Austin (United States))

1991-03-01

200

Jurassic stratigraphy of the Wiggins Arch, Mississippi  

SciTech Connect

Mobil and Shell jointly explored the Wiggins arch area in southern Mississippi from 1985 to 1991. The effort concentrated on the Jurassic Norphlet and Smackover formations. Two wells were drilled into Paleozoic crystalline rocks and one well into the Pine Hill formation. Two of these wells were located on the southern side of the Wiggins arch and provide significant data for interpreting Jurassic stratigraphy. The Mobil No. 1 U.S.A. well encountered a complete Jurassic section, but with some significantly different facies than those encountered by wells to the north. A granite wash section is the equivalent to the Frisco City formation previously only found 100 mi to the north-northeast. All 300 ft of Smackover is crystalline dolomite. The Norphlet section is entirely granite wash. The Pine Hill anhydrite is unusually thick and interpreted to be equivalent to the Louann Salt. Correlations to other wells on the Wiggins arch, particularly the Conoco No. 1 Higgins, indicate that the Jurassic can be divided into three transgressive events separated by the Norphlet/Pine Hill and Frisco City/Buckner regressive events.

Rhodes, J.A.; Maxwell, G.B. (Mobil Oil Company, Houston, TX (United States))

1993-09-01

201

Interpretation of seismic stratigraphy on the Amazon continental shelf  

SciTech Connect

The stratigraphy of the Amazon subaqueous delta has been examined using high-resolution reflection profiles. 15 piston cores from the Amazon Shelf were used to interpret the significance of the reflectors evident in the seismic profiles. Acoustic reflectors correlate with changes in grain size within cores, and generally represent coarser layers within the muddy deposits of the delta. Measurement of compressional-wave seismic velocity and saturated bulk density demonstrate that the correlation results from changes in acoustic impedance, caused by the grain-size variations. The reflectors reveal two predominant types of seismic stratigraphy: depositional and erosional. The depositional stratigraphy contains reflectors formed by relatively subtle change in grain size. Gently dipping topset and steeply dipping foreset demonstrate upward and seaward progradation of the subaqueous delta. This stratigraphy is truncated by erosional reflectors, which are significantly coarser layers. The erosional reflectors divide the depositional stratigraphy into distinct sets. The prevalence of erosional reflectors is greatest in the topset region near the river mouth, suggesting that sediment in this region, which is rapidly accumulating on 100-year time scales, has been eroded over longer time scales within the Holocene.

Alexander, C.R. Jr.; Nittrouer, C.A.; Demaster, D.J.

1985-01-01

202

Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris  

NASA Astrophysics Data System (ADS)

New high-resolution spectral and morphologic imaging of deposits on walls and floor of Ius Chasma extend previous geomorphic mapping, and permit a new interpretation of aqueous processes that occurred during the development of Valles Marineris. We identify hydrated mineralogy based on visible-near infrared (VNIR) absorptions. We map the extents of these units with CRISM spectral data as well as morphologies in CTX and HiRISE imagery. Three cross-sections across Ius Chasma illustrate the interpreted mineral stratigraphy. Multiple episodes formed and transported hydrated minerals within Ius Chasma. Polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma. They may have been precipitates in a closed basin or diagenetically altered after deposition. Fluvial or aeolian processes then deposited layered Fe/Mg smectite and hydrated silicate on the chasma floor, postdating the sulfates. The smectite apparently was weathered out of Noachian-age wallrock and transported to the depositional sites. The overlying hydrated silicate is interpreted to be an acid-leached phyllosilicate transformed from the underlying smectite unit, or a smectite/jarosite mixture. The finely layered smectite and massive hydrated silicate units have an erosional unconformity between them, that marks a change in surface water chemistry. Landslides transported large blocks of wallrock, some altered to contain Fe/Mg smectite, to the chasma floor. After the last episode of normal faulting and subsequent landslides, opal was transported short distances into the chasma from a few m-thick light-toned layer near the top of the wallrock, by sapping channels in Louros Valles. Alternatively, the material was transported into the chasma and then altered to opal. The superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential, distinct aqueous environments, characterized by alkaline, then circum-neutral, and finally very acidic surface or groundwater chemistry.

Roach, Leah H.; Mustard, John F.; Swayze, Gregg; Milliken, Ralph E.; Bishop, Janice L.; Murchie, Scott L.; Lichtenberg, Kim

2010-03-01

203

Middle Jurassic stratigraphy in the southwestern part of the Republic of Tatarstan  

NASA Astrophysics Data System (ADS)

Data on the structure of the Middle Jurassic marine deposits in the vicinity of Ulyanovsk (sections of the Tarkhanovskaya Pristan-Dolinovka profile) are generalized with due regard for ammonites, bivalves, and microfossils occurring in sediments. Outcrops of the Tarkhanovskaya Pristan site represent the northernmost Bajocian section of the Russian Platform, where ammonites of Tethyan origin are identified. As is established, the pre-Callovian sand-clay sequence formerly attributed to the Bathonian includes the Garantiana beds of the upper Bajocian in its middle part. The multidisciplinary biostratigraphic-sedimentological research showed that downwarping of the Ulyanovsk-Saratov basin and origin of the Simbirsk Bay of the Tethyan marginal sea commenced in the Bajocian Age. The identified fossils of the upper Bajocian and lower and upper Callovian are cited in paleontological plates of this work.

Mitta, V. V.; Kostyleva, V. V.; Glinskikh, L. A.; Shurygin, B. N.; Starodubtseva, I. A.

2014-01-01

204

Seismic stratigraphy of Lake Van, eastern Turkey  

NASA Astrophysics Data System (ADS)

More than 1500 km of multi-channel seismic reflection profiles combined with ICDP (International Continental Scientific Drilling Program) drilling data, provide important insights into the stratigraphic evolution of Lake Van, eastern Turkey. Three major basins (Tatvan, Northern and the Deveboynu basins) comprise the main lake basin and are separated by morphological highs (Ahlat ridge and Northern ridge). Moreover, NE-SW faults, parallel to the general tectonic lineament of the area, dominate the entire basin and are in charge of creating graben and half-graben structures. Well-developed prograding deltaic sequences on top of the basement were recognized by seismic stratigraphy analysis. Most likely, they formed during the initial flooding of Lake Van ?600 ka. The Tatvan basin sediments are dominated by mass-flow deposits of various origins alternating with undisturbed lacustrine sediments including distinct tephra layers. Faulting along the Tatvan basin margins may have triggered margin-wide slope failures. Ahlat ridge started to form between ca 340 ka-290 ka. Since then, Ahlat ridge was sheltered from major mass-flows due to its elevation. Hence, slow lacustrine sedimentation has prevailed throughout lake history on Ahlat ridge, which was the location of the main drill site during the ICDP. Several lake level fluctuations are evident on the eastern slope area but the deep basins were permanently covered by water. A significant lake-level low stand (ca 600 ka BP) was found at ?610 m below present lake level. The setting of the lake changed at about 30 ka. Tectonic activity appears to have waned significantly as the mass-transport deposition decreased across the Tatvan basin while normal undisturbed lacustrine sedimentation prevailed. A different setting is found in the Northern basin from ca 90 ka to Present, especially due to the strong influx of mostly volcaniclastic turbidites causing sedimentation rates to be about 3.5 times higher (drill Site 1), than at Site 2 (Ahlat ridge).

Cukur, Deniz; Krastel, Sebastian; Schmincke, Hans-Ulrich; Sumita, Mari; Ça?atay, M. Nam?k; Meydan, Aysegül Feray; Damc?, Emre; Stockhecke, Mona

2014-11-01

205

Sedimentological Reinterpretation of Surficial Unconsolidated Debris Flows and Stream Deposits of the Southern Flanks of Grand Mesa, CO: An Integrated LiDAR Approach  

E-print Network

. This study developed a sedimentological description and interpretation of these deposits and tested the capabilities of terrestrial LiDAR (Light Detection and Ranging) for use in sedimentological studies. This research addressed the origin of the deposits...

Blakeley, Mitchell W.

2014-08-08

206

GARY KOCUREK Department of Geological Sciences, Jackson School, University of Texas, 1 University Station  

E-print Network

.D., Geology, University of Wisconsin, 1980 RESEARCH AREAS: Sedimentology, stratigraphy, geomorphology, aeolian ­ Sedimentary Geology, Sedimentology, Summer Field Camp, Field Methods, Geology of the National Parks, Earth Committee, First International Conference on Mars Sedimentology & Stratigraphy, 2009 - 2010, El Paso Field

Yang, Zong-Liang

207

What can I do with this major? AREAS EMPLOYERS  

E-print Network

Energy Sources) Stratigraphy Sedimentology Structural Geology Geophysics Geochemistry Economic Geology. #12;STRATEGIESEMPLOYERSAREAS (Geology, Page 2) ENVIRONMENTAL GEOLOGY GEOLOGIC MAPPING Sedimentology. Structural Geology Stratigraphy Sedimentology Remote Sensing Federal government agencies: US Geological

Berdichevsky, Victor

208

A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides  

NASA Astrophysics Data System (ADS)

Sedimentologic and AMS 14C age data are reported for calcareous hemipelagic mud samples taken from gravity cores collected at sites within, or adjacent to five submarine landslides identified with multibeam bathymetry data on the Nerrang Plateau segment and surrounding canyons of eastern Australia's continental slope (Bribie Bowl, Coolangatta-2, Coolangatta-1, Cudgen and Byron). Sediments are comprised of mixtures of calcareous and terrigenous clay (10-20%), silt (50-65%) and sand (15-40%) and are generally uniform in appearance. Their carbonate contents vary between and 17% and 22% by weight while organic carbon contents are less than 10% by weight. Dating of conformably deposited material identified in ten of the twelve cores indicates a range of sediment accumulation rates between 0.017mka-1 and 0.2 mka-1 which are consistent with previous estimates reported for this area. One slide-adjacent core, and four within-landslide cores present depositional hiatus surfaces located at depths of 0.8 to 2.2 meters below the present-day seafloor and identified by a sharp, colour-change boundary; discernable but small increases in sediment stiffness; and a slight increase in sediment bulk density of 0.1 gcm-3. Distinct gaps in AMS 14C age of at least 20ka are recorded across these boundary surfaces. Examination of sub-bottom profiler records of transects through three of the within-slide core-sites and their nearby landslide scarps available for the Coolangatta-1 and Cudgen slides indicate that: 1) the youngest identifiable sediment layer reflectors upslope of these slides, terminate on and are truncated by slide rupture surfaces; and 2) there is no obvious evidence in the sub-bottom profiles for a post-slide sediment layer draped over or otherwise burying slide ruptures or exposed slide detachment surfaces. This suggests that both these submarine landslides are geologically recent and suggests that the hiatus surfaces identified in Coolangatta-1's and Cudgen's within-slide cores are either: a) erosional features that developed after the occurrence of the landslide in which case the hiatus surface age provides a minimum age for landslide occurrence or b) detachment surfaces from which slabs of near-surface sediment were removed during landsliding in which case the post-hiatus sediment dates indicates approximately when landsliding occurred. In either case, it is reasonable to suggest that these two spatially adjacent slides occurred penecontemporaneously approximately 20,000 years ago.

Clarke, S. L.; Hubble, T.; Webster, J.; Airey, D.; De Carli, E.; Ferraz, C.; Reimer, P. J.; Boyd, R.; Keene, J.

2013-12-01

209

Aragats stratovolcano in Armenia - volcano-stratigraphy and petrology  

NASA Astrophysics Data System (ADS)

In this contribution we discuss the geological structure and volcano-stratigraphy of the Quaternary Aragats stratovolcano in Armenia based on recent age determinations as well as petrological and geochemical features of magma generation processes specific for collision zones. Armenia is situated in the NE part of the Anatolian-Armenian-Iranian plateau, an intensely deformed segment of the Alpine-Himalayan belt. The complex geological structure of the region is represented by a mosaic of tectonic blocks comprising fragments of volcanic arcs, continental crust and exhumed oceanic crust. Collision of the Arabian plate with the Eurasian margin in early Miocene resulted in orogenic uplift associated with intense volcanism. Aragats (4090m) is one the largest volcanoes in the entire region and produced central vent (inc. Plinian VEI>4) and monogenetic type flank eruptions and periphery plateaus within a total area greater than 5000 km2, known as Aragats volcanic province (AVP). The Aragats volcanic province (AVP) comprises the composite cone of Aragats volcano, the peak of which is built on a summit plateau, ~45 km in diameter shield structure with dozens of flank vents, scattered monogenetic cinder cones on the adjacent volcanic plateaus as well as the neighboring stratovolcano Arailer. New K-Ar and 40Ar/39Ar age determinations of groundmass and separated plagioclase samples indicate that volcanism at AVP began ~2.5 Ma, while most recent volcanic activity is 0.49 Ma for Plinian eruption of dacites from Irind flank vent and basaltic trachyandesite lava flows from Tirinkatar (0.48-0.61 Ma), Kakavasar, (0.52-0.54 Ma) and Ashtarak (0.58 Ma) monogenetic flank centers, as well as trachyandesites of Jrbazhan volcano on the summit plateau of Aragats (0.52 Ma). Based on bulk rock geochemical data (major, minor and low abundance trace elements, Sr and Nd isotopes) and mineral chemistry, we conclude that volcanic rocks of AVP are largely recording a complex mixing between deep asthenospheric mantle and remnants of subduction-modified and metasomatically enriched mantle sources, followed by fractionation in large magma chamber(s). Mineral-melt equilibria studies reveal dry (<1%H2O) and very hot source, fluid inclusions study reveal pronounced enrichment with CO2 over H2O in fluid phase. Noteworthy are high eruption temperatures compared to global volcanic arcs, explaining the very long (up to 25 km) and thick (>200m) trachydacitic lava flows.

Meliksetian, Khachatur; Savov, Ivan; Connor, Charles; Halama, Ralf; Jrbashyan, Ruben; Navasardyan, Gevorg; Ghukasyan, Yura; Gevorgyan, Hripsime; Manucharyan, Davit; Ishizuka, Osamu; Quidelleur, Xavier; Germa, Aurélie

2014-05-01

210

Stratigraphy of Late Pleistocene formations of the Mezen river valley  

NASA Astrophysics Data System (ADS)

Stratigraphy of Late Pleistocene formations of the Mezen river valley A.V. Maksimov, L.R. Semenova A.P. Karpinski All-Russian Geological Research Institute (VSEGEI), St.-Petersburg, Russia In recent years received extensive and contradictory evidence on the genesis, age and area of spreading of quaternary formations in NW Russia. The reason for this - the heterogeneity of investigated objects and methods of research. Within a valley of the river Mezen quaternary sediments are distributed everywhere. In outcrops opened sediments relating to the fifth and sixth stages of Middle Pleistocene, Upper Pleistocene and Holocene. Thickness of the quaternary sediments varies over a wide range, generally increasing from west to east. The authors have studied quaternary formations, opened in outcrops in valley of river Mezen (downstream) and its right tributary Peza, as well as in marine coastal cliffs. The aim of the study was to demonstrate specific features of the lithological composition of quaternary sediments from various (in age and origin) moraine complexes of the Russian NW and to reconstruction of paleogeographic sedimentary environments in the Late Pleistocene. Such attention to glacial sediments was dictated by the fact that they bear the most valuable information pertaining to the type and composition of provenances and to the geodynamic settings of feeding and sedimentation zones. To achieve these goals following tasks were set: 1. Lithostratigraphic subdivision of the section of Quaternary sediments. 2. Correlation of local stratigraphic units with stratigraphic scheme adjacent areas using the geochronological, paleontological and paleoclimatic data. 3. Reconstruction of the main geological events Late Pleistocene NW European part of Russia. First for glacial sediments in valley of the river Mezen applied lithological method, for determining the origin of formations. Was studied lithological composition of the sediments and were correlated geological sections. Also was conducted geochronological research. Based on these results, it was found that: - the glaciers of the Baltic Shield and the Czech lip penetrated into the valley of the river Mezen in Valdai time, forming moraines of different lithology; - sea waters penetrated to the valley of the river Mezen in Leningrad and Mikulino time. In Mikulino time the basin was deeper.

Maksimov, Anton; Semenova, Ljudmila

2014-05-01

211

Sedimentologic and biostratigraphic implications for early Eocene lacustrine systems, eastern Great Basin, Nevada  

SciTech Connect

A multidisciplinary study integrating sedimentology, molluscan paleontology and paleoecology, structural and geologic mapping, and [sup 40]Ar/[sup 39]Ar dating of volcanic flows indicates the White Sage Formation north of the Deep Creek Range on the NV-UT border was deposited during the early Eocene in marginal-lacustrine, lacustrine, freshwater-marsh, and minor terrestrial settings. Sedimentary facies include wave-reworked, locally derived Paleozoic carbonate-clast basal conglomerates in contact with bedrock; carbonate tufa mounds; organic-rich mudstones; and laminated to medium-bedded carbonates. The wave-reworked conglomerate implies a broad lake with considerable fetch to generate large waves, but one with only small drainage basins with sharp relief to supply the locally-derived clasts. There is a striking lack of any fluvial, deltaic, or alluvial-fan deposits that would indicate development of substantial drainage areas. The large tufa mounds indicate a high-wave-energy shoaling environment with stable substrate and topography. The profusion of lacustrine carbonates indicates dominantly chemical- or biochemical-induced deposition in a carbonate-saturated lake. The aquatic molluscan fauna indicates shallow, quiet lacustrine conditions with emergent vegetation. The limpets inhabited areas of rooted aquatic vegetation, and the terrestrial gastropods indicate marshes adjacent to the lacustrine system. The molluscan assemblage constrains the age of the White Sage as early Eocene, indicating a lacustrine system equivalent to the Sheep Pass Formation and to outcrops near Illipah, NV that have similar facies and molluscan faunas and that also lack significant fluvial, deltaic, or alluvial fan deposits. The data are consistent with a model wherein the White Sage, Sheep Pass, and Illipah carbonates were deposited in a large lake superimposed on preexisting topography with low relief and little or no syndepositional extension.

Dubiel, R.F.; Potter, C.J.; Snee, L.W. (Geological Survey, Denver, CO (United States)); Good, S.C. (State Univ. Coll., Cortland, NY (United States))

1993-04-01

212

Geometric and sedimentologic characteristic of Mid-Miocene lowstand reservoir sandstones, offshore northwest Java, Indonesia  

SciTech Connect

Numerous reservoirs in the Upper Cibulakan Formation (Mid-Miocene) of the Offshore Northwest Java shelf occur in sharp-based sandbodies that range from less than 1 m up to 10 m in thickness. Well-log derived net-sand isopach and seismic amplitude maps of these sandbodies depict elongate features, that are 1-2 km wide and 5-8 km long. The orientation of the longest axis of these sandbodies is predominantly north-south. Conventional cores reveal that these sandbodies are burrowed to completely bioturbated sandstones. Common trace fossils associated with these sandbodies include Ophiomorpha, Teichichnus and Thalassinoides. The lower contact of these sands is typically sharp and is commonly associated with a Glossifungites surface and siderite mud clasts. Overlying and underlying mudstones are relatively devoid of burrowing. Benthonic foraminifera assemblages within these mudstones indicate inner to outer neritic conditions in a relatively restricted marine setting. The upper contact of these sandstones is gradational over a 0.5 to 1m interval. Sandbodies of the same age and similar facies were observed in outcrops in onshore west Java. Here, they can be observed to pinch out over a distance of 500 m. The lower bounding contact appears discordant with underlying interbedded sandstones and mudstones. Several of the sandstones contain abundant accumulations of the large, open marine, benthonic foraminifera Cycloclypeus and Lepidocyclina. Occasionally the concentration of these large foraminifera form limestones within the sharp-based sandbodies. These bioclastic deposits commonly exhibit planar-tabular and trough cross-stratification. The sandbodies are interpreted as having been emplaced during relative falls in sea-level within a large Mid-Miocene embayment. Our understanding of their geometry and sedimentologic characteristics is leading to a more effective exploitation strategy for these sandbodies in the Offshore Northwest Java area.

Lowry, P.; Kusumanegara, Y.; Warman, S. [ARCO Indonesia, Jakarta (Indonesia)

1996-12-31

213

Morphologic and sedimentologic characteristics of continental slope box slides offshore Fraser Island, Queensland, Australia  

NASA Astrophysics Data System (ADS)

The Fraser Island Slide complex is located on eastern Australia's continental slope offshore Fraser Island in southern Queensland. Morphologic, sedimentologic and geomechanical properties data for two submarine landslides, the 'North Fraser Island Upper Slope Slide' (upper slope slide) and the 'Fraser Island Middle Slope Slide' (middle slope slide) are described. Both of these features are box-shaped, slide scars from which rectangular slabs of material have been shed. The upper slope slide is situated at a water depth of approximately 750 m at the northern end of the Fraser Canyon. The head of this slide has apparently detached from a structural surface comprised of a Miocene reef complex located beneath the continental shelf edge; this slide is estimated to be 25 square kilometres in area and an average of 100m thick. The middle slope slide is situated in 1500 m of water at the southern end of the Fraser Canyon. It estimated to be 12 square kilometres in area and 50 m thick. Cores taken in the continental slope within both slides are long (upper slope 5.65 m, middle slope 3.64 m) and are dominantly comprised of hemipelagic mud. Cores taken adjacent to both slides are short (upper slope 1.33m, middle slope 0.43m) and terminate in stiff muds of suspected Miocene or Pliocene age. Additionally, the 1.33 m core on the slope adjacent to the upper slide presents a near surface layer of upper-fining of coarse to fine shelly sand which we interpret to be a turbidite deposit, this layer was deposited within hemipelagic muds which are ubiquitously present on the upper eastern Australian Continental Slope in New South Wales and Southern Queensland.

Fletcher, Melissa; Hubble, Thomas; Clarke, Samantha; Airey, David; Yu, Phyllis; Southern Surveyor V01-2013, Scientific Party RV

2014-05-01

214

Workshop on quantitative dynamic stratigraphy. Final conference report  

SciTech Connect

This document discusses the development of quantitative simulation models for the investigation of geologic systems. The selection of variables, model verification, evaluation, and future directions in quantitative dynamic stratigraphy (QDS) models are detailed. Interdisciplinary applications, integration, implementation, and transfer of QDS are also discussed. (FI)

Cross, T.A.

1988-04-01

215

The volcanic stratigraphy and petrogenesis of the Oman ophiolite complex  

Microsoft Academic Search

The volcanic stratigraphy and trace element geochemistry of the Oman ophiolite complex indicate a multistage magmatic origin comprising: (1) magmatism due to sea-floor spreading in a marginal basin; (2) magmatism associated with discrete submarine volcanic centres or seamounts; (3) magmatism associated with crustal uplift and rifting; and (4) magmatism associated with continent-arc collision.

T. Alabaster; J. A. Pearce; J. Malpas

1982-01-01

216

ORIGINAL ARTICLE Phylogenetic stratigraphy in the Guerrero Negro  

E-print Network

ecology Keywords: Guerrero Negro; rRNA phylogeny; microbial mats; microbial ecology; QIIME IntroductionORIGINAL ARTICLE Phylogenetic stratigraphy in the Guerrero Negro hypersaline microbial mat J Kirk, University of Colorado at Boulder, Boulder, CO, USA The microbial mats of Guerrero Negro (GN), Baja

217

Geochemical stratigraphy and magmatic evolution at Arenal Volcano, Costa Rica  

E-print Network

Geochemical stratigraphy and magmatic evolution at Arenal Volcano, Costa Rica Louise L. Bolge a Miravalles (OSIVAM), Instituto Costarricense de, Electricidad (ICE), Apdo. 10032-1000, Costa Rica Received 13; tephrostratigraphy; Central American arc 1. Introduction Arenal is a small strato volcano located in Costa Rica (10

218

Clastic sedimentology and detrital geochronology: deciphering the growing phase of the Variscan belt.  

NASA Astrophysics Data System (ADS)

The late Palaeozoic Variscan Orogeny results from the convergence between two major plates: Laurussia and Gondwana. The relief created during the Variscan Orogeny has now been completely eroded away. However, the Devonian and Carboniferous sediments potentially record the birth of the relief and the exhumation of rocks during the early stages of this orogenesis. A multidisciplinary approach (structural, sedimentology and geochronology) is used in order to constrain the palaeogeography and the nature of the material being eroded during the growth of the Variscan belt. More specifically, two detrital dating methods, U/Pb on zircon and 39Ar-40Ar on white mica, are used as complementary tools in order to decipher the age of the detrital material sources. The weakly deformed Ordovician to Carboniferous sediments of the Mauges Unit (South-Armorican Domain, France) are located in the internal zones of the Variscan belt. Two Formations, respectively the Sainte-Anne Fm of Emsian (late Lower Devonian) age and the Ancenis Fm of Visean (Lower Carboniferous) age, are made up of gravity flow deposits that record the creation of a nearby relief. The pre-orogenic Sainte-Anne Fm consists of immature sandstones with a large amount of lithic fragments of mainly sedimentary and volcanic origin. Among the detrital zircons analyzed, a population dated at ca. 400 Ma is therefore contemporaneous to the sedimentation and is interpreted as volcanic in origin. Considering the tectonic setting proposed for the area, these detrital zircons could record the creation of a magmatic arc. The late-orogenic Ancenis Fm was deposited after the crustal stacking that occurred close to the Devonian/Carboniferous boundary (Champtoceaux Complex, Bosse et al., 2000; Pitra et al., 2009). Carboniferous sedimentation took place in a basin preserved due to a reactivation of the suture zone. The Ancenis Fm is a lacustrine to continental deposit, 3- to 6 km thick, and displays a coarsening-upwards mega-sequence; this implies that relief and subsequently the material removed were increasingly closer to the sedimentation area. This trend is associated with surface uplift and the progressive exhumation of Variscan magmatic and metamorphic rocks, as shown by the progressive appearance of younger zircons and/or white micas in the detrital record. In this study, the detrital record within the basin will be compared to the evolution of metamorphic and magmatic rocks in underlying units.

Ducassou, Céline; Ballèvre, Michel; Poujol, Marc; Ruffet, Gilles; Gallagher, Kerry

2010-05-01

219

Glacioeustatic fluctuation: The mechanism linking stable isotope events and sequence stratigraphy from the early Oligocene to middle Miocene  

SciTech Connect

One of the most difficult challenges of sequence stratigraphy is the establishment of synchronism between events observed in widely-separated basins. Problems arise because the resolution of the best stratigraphic methods is not good enough to establish the synchronism of similar-aged events on a global scale. Unless a common mechanism affecting global eustasy is assumed, such as variations in the ice volume, there is no a priori reason to expect that sequences of similar age in widely-separated basins are indeed synchronous. The stable oxygen isotope composition of marine carbonates is a proxy for sea level which has been underutilized in sequence stratigraphy. Identification of isotope events is based on d[sup 18]O data from DSDP and ODP sites 522, 529, 563, 608, and 747 drilled in the Atlantic and Indian oceans. These records were used to define Oligocene and Miocene oxygen isotope zones. In addition, we present isotope data from PETROBRAS Well A drilled in the Campos Basin (Brazil). Ages of isotope events correspond well with the ages of sequence boundaries and maximum flooding surfaces. Because of the good correlation between the isotope and sequence stratigraphic records, we reconfirm that ice-volume change is the common mechanism driving sea-level fluctuations from the Oligocene to present.

Abreu, V. (Petrobras and Rice Univ., Houston, TX (United States)); Haddad, G. (Rice Univ., Houston, TX (United States))

1996-01-01

220

Glacioeustatic fluctuation: The mechanism linking stable isotope events and sequence stratigraphy from the early Oligocene to middle Miocene  

SciTech Connect

One of the most difficult challenges of sequence stratigraphy is the establishment of synchronism between events observed in widely-separated basins. Problems arise because the resolution of the best stratigraphic methods is not good enough to establish the synchronism of similar-aged events on a global scale. Unless a common mechanism affecting global eustasy is assumed, such as variations in the ice volume, there is no a priori reason to expect that sequences of similar age in widely-separated basins are indeed synchronous. The stable oxygen isotope composition of marine carbonates is a proxy for sea level which has been underutilized in sequence stratigraphy. Identification of isotope events is based on d{sup 18}O data from DSDP and ODP sites 522, 529, 563, 608, and 747 drilled in the Atlantic and Indian oceans. These records were used to define Oligocene and Miocene oxygen isotope zones. In addition, we present isotope data from PETROBRAS Well A drilled in the Campos Basin (Brazil). Ages of isotope events correspond well with the ages of sequence boundaries and maximum flooding surfaces. Because of the good correlation between the isotope and sequence stratigraphic records, we reconfirm that ice-volume change is the common mechanism driving sea-level fluctuations from the Oligocene to present.

Abreu, V. [Petrobras and Rice Univ., Houston, TX (United States); Haddad, G. [Rice Univ., Houston, TX (United States)

1996-12-31

221

New considerations on the stratigraphy and environmental context of the oldest (2.34 Ma) Lokalalei archaeological site complex of the Nachukui Formation, West Turkana, northern Kenya Rift  

NASA Astrophysics Data System (ADS)

At the northwest end of the Lake Turkana Basin (northern Kenya Rift), intensive fieldwork conducted on the Plio-Pleistocene fluvio-lacustrine Nachukui Formation by the National Museums of Kenya and the West Turkana Archaeological Project (WTAP), led to the discovery of more than 50 archaeological sites aged between 2.4 and 0.7 Ma. Among them is the Lokalalei archaeological site complex, which includes the two oldest archaeological sites (2.34 Ma) found in the Kenyan segment of the East African Rift System. The environmental background of the two sites was described as a succession of ephemeral streams with floodplain palaeosols in which the archaeological sites are situated, bordering the western bank of a large axial meandering river flowing southward. The Lokalalei 1 (LA1) and Lokalalei 2C (LA2C) archaeological sites are of extreme importance in terms of knowledge of hominins' knapping activities. The stratigraphic position of the LA1 and LA2C sites as well as implications on the technical differences between the two sites have been successively discussed by Roche et al. (1999), Brown and Gathogo (2002), and Delagnes and Roche (2005). In terms of stratigraphic position, Lokalalei 2C was estimated to be slightly higher in the section (i.e. younger) than Lokalalei 1. An alternative stratigraphic correlation was proposed by Brown and Gathogo (2002), who suggested that LA2C site should have been approximately 100,000 years younger than LA1. New considerations on the stratigraphy and environmental context of the Lokalalei sites have been developed following controversy on the stratigraphic position and time interval between the LA1 and LA2C sites. High-resolution lithostratigraphic work based on bed-to-bed field correlations, facies sedimentology and tephra geochemistry confirms that the LA2C site is slightly higher in the section than the LA1 site by about 11.20 m. This represents a time interval of ˜74,000 years based on an assumed sedimentation rate of 152 mm/ka. Sedimentary facies analysis indicates that the hominin occupation sites were situated in the vicinity of a lagoon/embayment environment close to the shoreline of an open lake. This lake was part of the broad lake development described across East Africa during the 2.7-2.4 Ma period. Palaeontological data associated with the sites suggest at the LA1 site a lake margin habitat, and at the LA2 sites an habitat with poor and sparse vegetation along channels of an alluvial fan system landward of the lake margin. They also confirm the aridity trend mentioned at the global scale for this period, which is demonstrated in the upper Lokalalei sediment sequence by progradation of an alluvial fan environment over the lake shoreline. Associated conglomeratic deposits could have been the source from which the knappers collected their raw materials. In addition, rapid variations from humid to arid episodes in a unique environment such as the East African Rift may have had a major influence in controlling hominin evolution.

Tiercelin, Jean-Jacques; Schuster, Mathieu; Roche, Hélène; Brugal, Jean-Philippe; Thuo, Peter; Prat, Sandrine; Harmand, Sonia; Davtian, Gourguen; Barrat, Jean-Alix; Bohn, Marcel

2010-09-01

222

Autocyclic progradation and allocyclic ravinement of a shoreface: Sedimentology and sequence stratigraphy of the Panther Sandstone Tongue (Upper Cretaceous, Campanian), Wasatch plateau, Utah, U. S. A  

SciTech Connect

The Panther Sandstone Tongue of the Star Point Formation exposed in the vicinity of Helper, Utah reflects a coarse-grained, clastic wedge that penetrated the Mancos Shale basin in Early Campanian (Late Cretaceous) time. Panther Sandstone rocks may be grouped into six lithofacies: (1) thin-bedded, bioturbated and rippled, mudstone and very fine-grained sandstone; (2) thin- to medium-bedded, bioturbated, rippled and parallel laminated, mudstone and very fine-grained sandstone; (3) thick- to very thick-bedded HCS and parallel-laminated, mudstone and fine- to medium-grained sandstone; (4) medium- to thick-bedded, Ophiomorpha bioturbated, medium- to coarse-grained sandstone; (5) medium- to very-thick bedded, current bedded and hydroplasticly deformed sandstone, and (6) medium- to thick-bedded, trough cross-stratified and bundle-laminated, fine grained sandstone. Lithofacies are arranged in definable vertical and lateral successions. L. 1, 2 and 3 are upward coarsening and shoaling and are common in the Helper area. L. 5 and 6 are common to the west. L. 4 is a transgressive and ravinement lag that rests on all other lithofacies. Interpreted environments reflect a storm modified, microtidal, strandplain system. Rocks, except L. 4, are contained in a parasequence system that built into the basin during relative sea-level fall. This system prograded episodically suggesting varying sediment supply and event-controlled sediment reworking -- responses associated with autocyclic forcing. In contrast, ravinement decapitated the parasequence intersecting progressively shallower lithofacies. These responses suggest that ravinement was driven by allocyclic forcing, perhaps in response to tectonism in the foreland.

Krause, F.F.; Aitken, S.A.; Braunberger, W.F.; Chung, P.; Macrae, A.; Meyer, R.O.; Nunez-Betelu, L.; Williams, C.A.; Hol, H.M. (Univ. of Calgary, Alberta (Canada))

1993-04-01

223

Stratigraphy, sedimentology, and ichnology of the Late Pennsylvanian Glenshaw Formation (Lower Conemaugh Group), southern Dunkard basin, Ohio-Kentucky-West Virginia  

SciTech Connect

Facies analysis of outcrops of the Glenshaw Formation was carried out at 45 localities over a 761 sq. km area. The glenshaw Formation is 61--76 m thick in the study area. Four marine units (Lower Brush Creek, Upper Brush Creek, Cambridge , and Ames) occur which contain invertebrate body fossils and/or trace fossils including Teichichnus, Rhizocorallium, Aulichnites, Paleophycus, Lockeia, and Curvolithus. Alluvial channel-fills contain internal features that reflect deposition in high sinuosity suspended or mixed load rivers. Paleocurrent data (N = 77) are broadly dispersed with a mean azimuth of 335 degrees. Overbank facies have yielded trackways from giant arthropods and Eryopoid amphibians (Limnopus). There are fewer marine units in the glenshaw than toward the north and west which has made direct detailed correlation of much of the formation problematic. The coal beds and marine units used previous stratigraphic studies may be extended through the recognition of non-coal-bearing paleosols and marine-influenced intervals distinguished by facies relations, and sedimentary and biogenic structures. Nine laterally persistent, paleosol-bounded packages occur which are comparable to allocyclic T-R units reported by Busch and Rollins (1984) from Pennsylvania and Ohio. Alternating episodes of soil formation and alluvial aggradation may reflect updip coastal plain responses to low stand incision of drainage lines and sediment bypassing followed by aggradation of alluvial systems in response to rising sea level. Climate changes may also have played a role in sediment flux.

Martino, R.L. (Marshall Univ., Huntington, WV (United States). Dept. of Geology)

1994-03-01

224

Stratigraphy, sedimentology and physical volcanology of the Henik Group, central Ennadai-Rankin greenstone belt, Northwest Territories, Canada: late Archean paleogeography of the Hearne Province and tectonic implications  

Microsoft Academic Search

Extensive areas of the Hearne and Rae provinces are underlain by Archean metavolcanic and metasedimentary rocks. In the Rae Province, supracrustal sequences with prominent continental to shallow-water quartz arenites have been interpreted by others as rift and passive margin deposits. In the Hearne Province to the southeast, the Ennadai-Rankin greenstone belt is exposed in an area ca. 700 × 200

Lawrence B. Aspler; Jeffrey R. Chiarenzelli

1996-01-01

225

The stratigraphy and palaeoenvironment of the Bathonian "Great Oolite Group" of Woodeaton Quarry, Oxfordshire.  

NASA Astrophysics Data System (ADS)

Woodeaton Quarry, Oxfordshire, represents the most continuously exposed section of the Upper Bathonian 'Great Oolite Group' in the United Kingdom. Like most of the British Bathonian, it is lacking in reliable ammonite zonation from which to define a chronostratigraphy. The sedimentology of the succession can be broken up into two broad facies types: A clay rich, brackish lagoonal environment with intermixed freshwater-influenced flora and fauna; A marginal marine calcareous succession of an oolitic nature with periodic mud-drape intervals. The marginal marine depositional setting, the completeness of the Upper Bathonian stratigraphy and lack of biostratigraphically important macrofauna has motivated this study into the micropalaeontology of Woodeaton. The primary aims of this study are to use foraminifera and ostracods to reconstruct the palaeoenvironments and to refine the biostratigraphy of the Upper Bathonian. The studied succession commences at the top of the Taynton Limestone Formation, which fines upwards into the clay-rich Rutland Formation. Several species of marine ostracods known from the Mid-Upper Bathonian are recovered from the base of the Rutland Formation, such as Praeschuleridea confossa and Angliaecytherldea calvata, as well as fragments of fish scales and elasmobranch teeth. Freshwater influence is evident further up the Rutland Formation where freshwater charophytes, nested bivalves and ostracods of the genus Bisulcocypris have been found. The progression from the Rutland Formation's marine base into the freshwater influenced clays is clear from the varied micropalaeontological fauna. A return to marine conditions in the overlying White Limestone Formation can be observed through the increasing number of benthic foraminiferal taxa - with Spirillina and Lenticulina the most abundant - compared to the Rutland Formation. Within the Shipton and Ardley Members there are also indicative marine ostracod taxa present (including Acanthocythere spiniscutulata and Terquemula robusta). The upper part of the section exposes the Bladon Member that displays a relative shallowing within the fimbriatus-waltoni beds preserving a number of in situ rootlets and exogenous carbonised logs. This unit contains a mixed assemblage of marine species of ostracods (e.g. Fossaterquemula blakeana) and foraminifera (e.g. Lenticulina tricarinella) in association with freshwater ostracod taxa such as Timiriasevia sp. The succession at Woodeaton Quarry of Upper Bathonian carbonates exhibits microfaunal assemblages that can be viewed as direct proxies to the palaeoenvironment. The assemblages of ostracods and foraminifera indicate marine conditions prevailed in the basal Rutland Formation before the evolution of a freshwater environment. A return to a marine dominated environment with freshwater fluctuations occurs throughout the White Limestone Formation. It is through the high-resolution micropalaeontological study that palaeoenvironmental analysis can be refined in the marginal marine settings of the Upper Bathonian in Oxfordshire.

Guthrie, Ronald; Stukins, Stephen; Raub, Tim

2014-05-01

226

Integrated stratigraphy of the Cenomanian-Turonian boundary interval: improving understanding of Oceanic Anoxic Events  

NASA Astrophysics Data System (ADS)

The Cenomanian-Turonian boundary (CTB) interval ~ 94 Ma represented a period of major global palaeoenvironmental change. Increasingly detailed multidisciplinary studies integrating sedimentological, palaeontological and geochemical data from multiple basins, are enabling the development of refined but complex models that aid understanding of the mechanisms driving changes in ocean productivity and climate. This paper reviews some of the exciting new developments in this field. Facies change characterizes the CTB interval in most areas. In the Chalk seas of northern Europe, a widespead hiatus was followed by the deposition of clay-rich organic-lean beds of the Plenus Marl and its equivalents, and then nodular chalks. In the North Sea basin and its onshore extension in eastern England and northern Germany, black shales of the Black Band (Blodøks Formation, Hasseltal Formation) occur. Similarly, in northern Tethys, a brief interval of black shale accumulation within a predominantly carbonate succession, is exemplified by the Niveau Thomel in the Vocontian Basin (SE France), and the Livello Bonarelli in Italy. Widespread deposition of organic-rich marine sediments during CTB times led to 12C depletion in surface carbon reservoirs (oceans, atmosphere, biosphere), and a large positive global ?13C excursion preserved in marine carbonates and both marine and terrestrial organic matter (Oceanic Anoxic Event 2). Significant biotic turnover characterises the boundary interval, and inter-regional correlation may be achieved at high resolution using integrated biostratigraphy employing macrofossils (ammonites, inoceramid bivalves), microfossils (planktonic foraminifera, dinoflagellate cysts) and calcareous nannofossils. Correlations can be tested against those based on comparison of ?13C profiles - carbon isotope chemostratigraphy, supplemented by oxygen isotope and elemental data. Interpretation of paired carbonate - organic matter ?13C data from multiple CTB sections implicates rising atmospheric pCO2 linked to volcanic outgassing as a major forcing mechanism for palaeoclimate warming and palaeoceanographic change accompanying OAE2. New marine 187Os/188Os isotope stratigraphy further reveals the interaction of volcanism and ocean circulation during OAE2, and provides a further chemostratigraphic tool. Li isotope (? 7Li) data may be interpreted as evidence that increased silicate weathering promoted by rising pCO2 acted as both a forcing and negative feedback mechanism driving OAE2 history. Neodymium and sulphur isotopes offer further insights into interactions between global biogeochemical cycles and ocean circulation changes.

Jarvis, Ian

2014-05-01

227

Stratigraphy and sequence stratigraphy of the Moscovian in the Donets basin  

NASA Astrophysics Data System (ADS)

New results are presented on the stratigraphy based on Fusulinids and Palynomorphs and the sequence stratigraphy of the Moscovian in the Donets basin. They have been developed by comparison of our observations on cross-sections near Artemovsk and the published coal mine logs of Artemovsk Geological Survey. The Moscovian of the Donets basin is equivalent to the uppermost Westphalian B and the Westphalian C and D of western Europe. In the Donets basin, the Moscovian forms a second-order sequence as in the Moscow basin, that can be subdivided into four third-order sequences, subdivided into fourth-order sequences. The upper Bashkirian shows two fourth-order sequences. The Vereian exhibits two fourth-order sequences. The Kashirian shows four fourth-order sequences. The Podolskian offers eight fourth-order sequences. The Myatchkovian presents four fourth-order sequences. These sequences begin with an erosive base and show a succession of elementary sequences with fluvial sandstone, coal seam, limestone and deltaic facies. The fluvial sandstone corresponds with an aggradation period, the coal and the limestone with a transgressive period and the deltaic facies with a progradation period. A decrease of the sandstone thickness and an increase of the marine deposits that are transgressive and regressive upwards are observed from the base to the top of sequences. These fourth-order sequences present a higher spatial amplitude than the third-order sequence and obscure these sequences. The second-order sequence equivalent to the Moscovian shows a lowstand system tract with more fluvial sandstone in the lower part of the Vereian, a transgressive system tract in the upper part of the Vereian, Tsinskaya and Kashirian, a maximum flooding period during the Podolskian and lower part of the Myatchkovian with more marine facies and a highstand system tract in the upper part of the Myatchkovian with more lagoonal and swampy palaeoenvironments. The sequences are controlled by the regional tectonic subsidence in the graben and the uplift of the horsts and/or by eustasy with either a plate-tectonic or a glacial origin. Other investigations, particularly radiometric dating, will be useful for solving this problem.

Izart, A.; Briand, C.; Vaslet, D.; Vachard, D.; Coquel, R.; Maslo, A.

1996-12-01

228

Stratigraphie et paléontologie (plantes, vertébrés) de la série paralique Albien terminal–Cénomanien basal de Tonnay-Charente (Charente-Maritime, France)  

Microsoft Academic Search

Stratigraphy and palaeontology (plants, vertebrates) of the paralic deposits from the Uppermost Albian–Lower Cenomanian of Tonnay-Charente (Charente-Maritime, France). The Tonnay-Charente area (Charente-Maritime, southwestern France) contains several sand and clay exploitations of Uppermost Albian and Lower Cenomanian ages. These sediments have been deposited in a coastal area where plant remains, amber, and aquatic or terrestrial vertebrates were trapped. The two last

Didier Néraudeau; Romain Vullo; Bernard Gomez; Vincent Perrichot; Blaise Videt

2005-01-01

229

Stratigraphy and paleoenvironment of the Danish Eocene Azolla event  

NASA Astrophysics Data System (ADS)

Spores (massulae and megaspores) of the freshwater fern Azolla are recorded in several Danish Eocene outcrops and boreholes. The Azolla-bearing interval is 0.5 - ca. 3 m thick and occurs within the L2 Bed, a unit in the lower part of the hemipelagic, bathyal Lillebælt Clay Formation deposited in the central and eastern parts of the North Sea Basin. Intervals of organic-rich clay, usually including two distinctive, black sapropels, are present in the lower part of Bed L2, indicating a generally reduced oxygen content in the bottom waters during this time, with at least two episodes of severe, basinwide stagnation. The oxygen-deficit points to reduced circulation and/or enhanced marine productivity in the North Sea Basin. Azolla occurs in the upper part of this mainly organic-rich interval. The frequency of Azolla spores relative to marine dinoflagellate cysts fluctuates within the interval. The Azolla interval has previously been correlated to levels near the Ypresian/Lutetian transition in Belgium, based on dinoflagellate stratigraphy. Calibration of a new magnetostratigraphic study of the lower Lillebælt Clay with the dinoflagellate biostratigraphy suggests that Bed L2 spans the upper part of Chron 22r, C22n and lower part of C21r. The Azolla pulse spans the upper part of C22n and lowermost part of C21r. The combined bio-magnetostratigraphy from Denmark allows a detailed comparison with published data from the northern part of the Norwegian-Greenland Sea (ODP Hole 913B). The correlation confirms earlier assumptions, which were based on biostratigraphy alone, that the marine Azolla pulse in the two areas, and therefore probably over the whole Norwegian-Greenland Sea - North Sea region, is of the same age. An ongoing palynological study of the L2 Bed has so far revealed no indication for freshwater episodes or brackish waters in the basin during the Azolla pulse, except perhaps for Azolla itself. It is, therefore, suggested that the Azolla spores were transported to the sea by rivers from swamps and lakes in coastal areas of surrounding landmasses. Azolla habitats may have existed in Fennosarmatia 200-400 km away. It is noteworthy that the Azolla pulse coincided with a major, apparently eustatic, sea-level fall or the slow subsequent transgression, during which widespread swamps may have formed in the coastal areas. The combination of a low sea-level and a warm, humid climate may have led to increased productivity, both in Azolla-swamps and in the adjacent marine waters. This may explain the presence of organic-rich marine clays with Azolla spores.

Heilmann-Clausen, Claus; Beyer, Claus; Snowball, Ian

2010-05-01

230

DALHOUSIE UNIVERSITY, DEPARTMENT OF EARTH SCIENCES Assistant Professor -Geophysics, Sedimentology, or Geochemistry  

E-print Network

DALHOUSIE UNIVERSITY, DEPARTMENT OF EARTH SCIENCES Assistant Professor - Geophysics, Sedimentology, or Geochemistry The Department of Earth Sciences at Dalhousie University invites applications for a faculty research projects. Essential qualifications include a Ph.D. in Earth Sciences or closely related field

Brownstone, Rob

231

Sedimentological characteristics and 3-D internal architecture of washover deposits from Hurricanes Frances, Ivan, and Jeanne  

Microsoft Academic Search

Extensive overwash occurred along Florida's Atlantic and northern Gulf facing barrier islands during the passages of Hurricanes Frances, Ivan, and Jeanne in 2004. These high-energy storm events provided a unique opportunity to study the spatial depositional patterns and internal sedimentary architecture of fresh washover deposits resulting from inundation to collision regime overwash events. Sedimentological characteristics and 3-D internal architecture of

Mark H Horwitz

2008-01-01

232

Effects of microbial activity on the hydrochemistry and sedimentology of Lake Logipi, Kenya  

Microsoft Academic Search

Lake Logipi is a saline soda and alkaline lake which marks the northern termination of the Suguta River drainage system. It also receives waters from streams, possible seepage from Lake Turkana, and hot springs. Present hydrochemistry and sedimentology is controlled by numerous factors including seasonal variations, composition of incoming waters, water depth and, above all, bacterial activity. Given the scarcity

Sabine Castanier; Marie-Claire Bernet-Rollande; André Maurin; Jean-Pierre Perthuisot

1993-01-01

233

Origin of shallow submarine mass movements and their glide planes—Sedimentological and geotechnical analyses from the continental slope off northern Norway  

NASA Astrophysics Data System (ADS)

landslides are often characterized by a basal surface of rupture parallel to the stratigraphy, in which downslope movement is initiated. However, little is known about the sedimentology and physical properties of the sediments within these surfaces. In this study, we present a multiproxy analysis of the sediments collected from a giant piston core penetrating a shallow submarine mass transport deposit, in combination with high-resolution seismoacoustic data to identify and characterize the basal glide plane and the weaker sediments in which movement was initiated. The initial phase of instability consists of a single fracture that formed due to the downslope movement of a mostly intact slab of sediments. The 16 m long core, comprising mostly undisturbed massive and laminated ice-rafted debris-rich clay penetrated this slab. The base of the slab is characterized by a high-amplitude semicontinuous reflection visible on the subbottom profiler data at about 12.5 m depth, interpreted to originate from the glide plane on top of a plumite deposit. This plumite has dilative behavior with pore pressure decrease with increasing shear strain and high undrained shear strength. Movement probably started within contouritic sediments immediately above the glide plane, characterized by higher sensitivities and higher water contents. The occurrence of the mass movements documented in this study are likely affected by the presence of a submarine landslide complex directly downslope. The slide scar of this landslide complex promoted retrogressive movement farther upslope and progressive spreading of strain softening along the slide base and in the slide mass. Numerical models (infinite slope, BING, and retrogressive slope models) illustrate that the present-day continental slope is essentially stable and allow reconstruction of the failure processes when initiated by an external trigger.

Baeten, Nicole J.; Laberg, Jan Sverre; Vanneste, Maarten; Forsberg, Carl Fredrik; Kvalstad, Tore J.; Forwick, Matthias; Vorren, Tore O.; Haflidason, Haflidi

2014-11-01

234

Archaeological sedimentology of overbank silt deposits on the floodplain of the Ohio river near Louisville, Kentucky  

USGS Publications Warehouse

The surface of the floodplain of the Ohio River about 20km southwest of Louisville, Kentucky, is a series of linear ridges and swales that are subparallel to the channel of the river, which here is relatively straight and flows southward. Numerous prehistoric occupational sites are located on these ridges. The sediments that underlie the ridges, which were examined in four archaeological excavations as deep as 8 m, are predominantly sandy silt and silty fine to very fine sand and appear to be mainly the product of overbank deposition from suspended load. Abundant cultural material and occupational sites dating as early as 10,000 years BP are found in the sediments at depths as great as 6??5 m. The fine sediments of the floodplain are underlain by sand and gravel. The context of the cultural materials and the stratigraphy and morphology of the deposits indicate that the ridged deposits began as linear riverside sand and gravel bars. These were succeeded upward by fine-grained overbank deposits in which the ridged morphology was maintained because the overbank silt and fine sand were deposited as prograding elongate bars at high water. As the floodplain ridge built upward, the sedimentation rate decreased and the sand content of the sediments diminished, and as the river channel occasionally shifted, the ridged deposits were built in successive subparallel sequences. Two archaeological consequences are implicit in this depositional model of orderly growth of the floodplain. First, available archaeological data from floodplain segments along other parts of the river should confirm the model; and second, the model should make it possible to search the floodplains of the Ohio River for stratified sites of any desired age. ?? 1984.

Gray, H.H.

1984-01-01

235

QUATERNARY RESEARCH 27, 1-29 (1987) Age Dating and the Orbital Theory of the Ice Ages: Development of a  

E-print Network

QUATERNARY RESEARCH 27, 1-29 (1987) Age Dating and the Orbital Theory of the Ice Ages: Development School Lane, Cambridge, England CB2 3RS Using the concept of "orbital tuning," a continuous, high is developed using a stacked oxygen-isotope stratigraphy and four different orbital tuning approaches, each

236

Tethyan-to-boreal correlation in the Kimmeridgian using high-resolution sequence stratigraphy (Vocontian Basin, Swiss Jura, Boulonnais, Dorset)  

NASA Astrophysics Data System (ADS)

Ammonite biostratigraphy plays a central role in the definition of Jurassic stratigraphy. Nevertheless, the strong provincialism of European ammonite species during the Kimmeridgian is a long-standing problem in correlation attempts between the boreal and Tethyan faunal realms. Moreover, the sequence-stratigraphic interpretations for northern and southern Europe given in the Jurassic chronostratigraphic chart of Hardenbol et al. in SEPM Publ. 60 (chart) (1998) are different. The present study aims to resolve this correlation problem in order to better understand the connections between the boreal and the Tethyan realms during the Kimmeridgian. A sedimentological and high-resolution sequence-stratigraphic interpretation is presented for two unpublished sections (Cras d’Hermont and Roche de Mars) in the northern Swiss Jura, where recently discovered ammonites display both boreal and Tethyan influences. Then, these sections are correlated with the same time interval in the central Swiss Jura and Vocontian Basin, which belong to the Tethyan realm. Lastly, a long-distance transect is constructed between the Vocontian Basin, Swiss Jura, northern France, and southern England, the last two areas being part of the sub-boreal realm. The main results of this work are that: (1) third-order depositional sequences, and also higher-frequency sequences, can be correlated from the Tethyan to the boreal realm; (2) the sequence-stratigraphic interpretation given by Hardenbol et al. in SEPM Publ 60 (chart) (1998) for northern Europe seems to be accurate and agrees with the sequence-stratigraphic framework established in the Swiss Jura; (3) the Late Kimmeridgian of the Swiss Jura displays boreal influences; (4) integrated high-resolution sequence-stratigraphic and cyclostratigraphic studies are a valuable approach for bridging the correlation gap between northern and southern Europe.

Colombié, C.; Rameil, N.

2007-06-01

237

Stratigraphy and palaeoenvironmental evolution of the mid- to upper Palaeozoic succession in Northwest Peninsular Malaysia  

NASA Astrophysics Data System (ADS)

The stratigraphy of the Devonian to Permian succession in Northwest Peninsular Malaysia is revised. The Timah Tasoh Formation consists of black mudstone containing graptolites and tentaculitids indicating a Pragian or earliest Emsian age. The Sanai Limestone overlies the Timah Tasoh Formation at Sanai Hill B and contains conodonts indicating a Late Devonian (Frasnian to possibly early Famennian) age. In other places, Late Tournaisian chert of the Telaga Jatoh Formation overlies the Timah Tasoh Formation. The overlying Kubang Pasu Formation is predominantly composed of mudstone and sandstone, and can be divided into 3 subunits, from oldest to youngest: (1) Chepor Member; (2) Undifferentiated Kubang Pasu Formation; (3) Uppermost Kubang Pasu Formation. The ammonoid Praedaraelites tuntungensis sp. nov. is reported and described from the Chepor Member of Bukit Tuntung, Pauh. The genus indicates a Late Viséan age for part of the subunit. Dropstones and diamictites from the Chepor Member indicate a glacial marine depositional environment. The Carbo-Permian, undifferentiated Kubang Pasu Formation consists of similar interbedded mudstone and sandstone. The uppermost Kubang Pasu Formation of Kungurian age consists of coarsening upward cycles of clastics, representing a shallow marine, wave- and storm-influenced shoreline. The Permian Chuping Limestone also represents shallow marine, wave- and storm-influenced deposits. A Mid-Palaeozoic Unconformity separating Early-Late Devonian rocks from overlying Late Devonian-Carboniferous deposits probably marks initiation of rifting on Sibumasu, which eventually led to the separation of Sibumasu from Australian Gondwana during the late Sakmarian (Early Permian).

Amir Hassan, Meor H.; Aung, Aye-Ko; Becker, R. T.; Abdul Rahman, Noor Atirah; Ng, Tham Fatt; Ghani, Azman A.; Shuib, Mustaffa Kamal

2014-04-01

238

Sequence stratigraphy of the Orange basin, western offshore South Africa  

Microsoft Academic Search

A seismic\\/sequence-stratigraphic framework for the siliciclastic fluvial to deepwater Cretaceous strata of the Orange basin has been constructed. Sequence-stratigraphic concepts developed by Exxon were used to interpret 10,000 km of seismic data and logs from 31 exploration boreholes within an area of 90,000 km². The sequence stratigraphy of the western margin exhibits 34 cyclical depositional sequences interpreted to document the

1991-01-01

239

Stratigraphy and Tectonics of Southeastern Serenitatis. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

Results of investigations of returned Apollo 17 samples, and Apollo 15 and 17 photographs have provided a broad data base on which to interpret the southeastern Serenitatis region of the moon. Although many of the pre-Apollo 17 mission interpretations remain valid, detailed mapping of this region and correlation with earth-based and orbital remote-sensing data have resulted in a revision of the local mare stratigraphy.

Maxwell, T. A.

1976-01-01

240

Changes in Colorado Subalpine Fen Peat Stratigraphy and Humification During the Holocene  

NASA Astrophysics Data System (ADS)

This project focuses on the record of peat stratigraphy and decomposition preserved in cores taken from minerotrophic peatlands in Colorado. Subalpine peatlands in the Colorado Rocky Mountains and in the Colorado Plateau cover only about 2% of the state's land area, yet these wetlands provide important wildlife habitat and ecosystem services. The peatlands in Colorado are fens, and, while summer precipitation contributes to the local hydrology, the fens are only found in locations where winter snowpack persists long enough into the summers to maintain sufficiently high water tables to preserve the peat. We hypothesized that changes in summer precipitation and winter snowpack through the Holocene would be evident in the degree of peat humification and stratigraphy. We were interested in determining how warmer summer conditions early in the Holocene influenced precipitation, particularly summer monsoons, and thus, groundwater. In addition, our research using lake sediment cores in the region indicates that sediment organic content may fluctuate with paleotemperature. We sought to determine whether fens likewise preserve evidence of relatively low magnitude temperature changes, including those associated with the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). Since fens persist in the region only under marginal conditions, they are very sensitive to fluctuations in climate and consequent hydrological responses. Nine fens were sampled in the study. Fen stratigraphy was studied at all of the sites. Humification analysis and bulk density and organic content determinations were conducted at one-centimeter intervals on cores from four of the fens. Core chronology was established using radiocarbon dating. Our results suggest that warmer summers in the early Holocene led to earlier snowmelt at lower elevations. Fens located near the lower margins of the subalpine zone (<3100 m elevation) ceased to accumulate peat during this period, changing to alluvial depositional environments, only returning to peat accumulation when cooler/moister conditions reestablished. This stratigraphic change is similar to that found by other researchers working in the Sierra Nevada, California. Higher elevation fens in Colorado persisted as peatlands throughout the Holocene, but warmer periods produced higher rates of peat accumulation and greater humification during these intervals. Peat humifiation and stratigraphic analyses indicate that the subalpine fens in Colorado preserve a sensitive record of Holocene climate change and ecohydrological conditions. Our results suggest that warmer summers over the next century will likely result in earlier snowmelt and the potential loss of lower elevation fens, and changes in peat accumulation in higher elevation fens in the subalpine zone. These changes will have significant impacts on water quality and hydrology in Colorado.

Sullivan, D. G.

2013-12-01

241

Sedimentological imprint on subseafloor microbial communities in Western Mediterranean Sea Quaternary sediments  

NASA Astrophysics Data System (ADS)

An interdisciplinary study was conducted to evaluate the relationship between geological and paleoenvironmental parameters and the bacterial and archaeal community structure of two contrasting subseafloor sites in the Western Mediterranean Sea (Ligurian Sea and Gulf of Lion). Both depositional environments in this area are well-documented from paleoclimatic and paleooceanographic point of views. Available data sets allowed us to calibrate the investigated cores with reference and dated cores previously collected in the same area, and notably correlated to Quaternary climate variations. DNA-based fingerprints showed that the archaeal diversity was composed by one group, Miscellaneous Crenarchaeotic Group (MCG), within the Gulf of Lion sediments and of nine different lineages (dominated by MCG, South African Gold Mine Euryarchaeotal Group (SAGMEG) and Halobacteria) within the Ligurian Sea sediments. Bacterial molecular diversity at both sites revealed mostly the presence of the classes Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria within Proteobacteria phylum, and also members of Bacteroidetes phylum. The second most abundant lineages were Actinobacteria and Firmicutes at the Gulf of Lion site and Chloroflexi at the Ligurian Sea site. Various substrates and cultivation conditions allowed us to isolate 75 strains belonging to four lineages: Alpha-, Gammaproteobacteria, Firmicutes and Actinobacteria. In molecular surveys, the Betaproteobacteria group was consistently detected in the Ligurian Sea sediments, characterized by a heterolithic facies with numerous turbidites from a deep-sea levee. Analysis of relative betaproteobacterial abundances and turbidite frequency suggested that the microbial diversity was a result of main climatic changes occurring during the last 20 ka. Statistical direct multivariate canonical correspondence analyses (CCA) showed that the availability of electron acceptors and the quality of electron donors (indicated by age) strongly influenced the community structure. In contrast, within the Gulf of Lion core, characterized by a homogeneous lithological structure of upper-slope environment, most detected groups were Bacteroidetes and, to a lesser extent, Betaproteobacteria. At both site, the detection of Betaproteobacteria coincided with increased terrestrial inputs, as confirmed by the geochemical measurements (Si, Sr, Ti and Ca). In the Gulf of Lion, geochemical parameters were also found to drive microbial community composition. Taken together, our data suggest that the palaeoenvironmental history of erosion and deposition recorded in the Western Mediterranean Sea sediments has left its imprint on the sedimentological context for microbial habitability, and then indirectly on structure and composition of the microbial communities during the late Quaternary.

Ciobanu, M.-C.; Rabineau, M.; Droz, L.; Révillon, S.; Ghiglione, J.-F.; Dennielou, B.; Jorry, S.-J.; Kallmeyer, J.; Etoubleau, J.; Pignet, P.; Crassous, P.; Vandenabeele-Trambouze, O.; Laugier, J.; Guégan, M.; Godfroy, A.; Alain, K.

2012-09-01

242

Clear Lake sediments: anthropogenic changes in physical sedimentology and magnetic response.  

PubMed

We analyzed the sedimentological characteristics and magnetic properties of cores from the three basins of Clear Lake, California, USA, to assess the depositional response to a series of land use changes that occurred in the watershed over the 20th century. Results indicate that distinct and abrupt shifts in particle size, magnetic concentration/mineralogy, and redox conditions occur concurrently with a variety of ecological and chemical changes in lake bed sediments. This coincidence of events occurred around 1927, a datum determined by an abrupt increase in total mercury (Hg) in Clear Lake cores and the known initiation of open-pit Hg mining at the Sulphur Bank Mercury Mine, confirmed by 210Pb dating. Ages below the 1927 horizon were determined by accelerator mass spectrometry on 14C of coarse organic debris. Calculated sedimentation rates below the 1927 datum are approximately 1 mm/yr, whereas rates from 1927 to 2000 are up to an order of magnitude higher, with averages of approximately 3.5-19 mm/yr. In both the Oaks and Upper Arms, the post-1927 co-occurrence of abrupt shifts in magnetic signatures with color differences indicative of changing redox conditions is interpreted to reflect a more oxygenated diagenetic regime and rapid burial of sediment below the depth of sulfate diffusion. Post-1927 in the Oaks Arm, grain size exhibits a gradual coarsening-upward pattern that we attribute to the input of mechanically deposited waste rock related to open-pit mining activities at the mine. In contrast, grain size in the Upper Arm exhibits a gradational fining-upward after 1927 that we interpret as human-induced erosion of fine-grained soils and chemically weathered rocks of the Franciscan Assemblage by heavy earthmoving equipment associated with a road- and home-building boom, exacerbated by stream channel mining and wetlands destruction. The flux of fine-grained sediment into the Upper Arm increased the nutrient load to the lake, and that in turn catalyzed profuse cyanobacterial blooms through the 20th century. The resulting organic biomass, in combination with the increased inorganic sediment supply, contributed to the abrupt increase in sedimentation rate after 1927. PMID:19475928

Osleger, David A; Zierenberg, Robert A; Suchanek, Thomas H; Stoner, Joseph S; Morgan, Sally; Adam, David P

2008-12-01

243

Stratigraphy and geochemistry of an early Aptian carbonate platform: interactions between relative sea level and environmental changes (Prebetic Zone, Spain)  

NASA Astrophysics Data System (ADS)

The Early Aptian was a time of development of large shallow carbonate platforms, punctuated with phases of growth crises and platform demise. Much research has been done over the past few years, focussed on characterizing the stratigraphic architecture of carbonate platforms and elucidating the possible link between platform demise and oceanic anoxic events. To explore this, we are investigating the Mariola stratigraphic section (Prebetic Zone, Betic Cordillera), deposited in the Southern Iberian Palaeomargin during the Mesozoic. The Lower Aptian of this section records the installation, development and demise of a carbonate platform, and the subsequent imprint of the OAE 1a. An integrated approach including sedimentology, biostratigraphy, and sequence stratigraphy, along with isotope stratigraphy, biomarker analysis and elemental geochemistry has been carried out. The studied section is located in the Sierra de Mariola, where the early Aptian succession is composed of three units: (1) The Llopis Fm., made of shallow platform carbonates with rudists, which is organized in a succession of shallowing-upwards parasequences defining a progradational-retrogradational cycle; (2) the Agres bed, formed by bioclastic calcarenites and marls, which represents a significant lithological and biotic change and is interpreted as deposited during a transgressive pulse coeval to a notable terrigenous input into the platform, and (3) the Almadich Fm., made of an alternation of marls and marlstones with planktonic foraminifers and ammonites, interpreted as the result of the drowning of the carbonate platform. The C-isotope curve shows a negative trend in the upper part of the Llopis Fm. with lowest values within the basal part of the Almadich Fm. This negative peak is followed by a positive shift, recorded within a level of organic-rich marls, considered to be the local record of the OAE1a. Finally, the values decrease through the upper part of the Almadich Fm. TOC values in the organic rich level vary between 0.2-0.6 wt.%. The biomarker characterization of the organic rich level has revealed that the organic matter is very immature and well preserved, and dominated by n-alkanes, with an important contribution of hopanes and minor amount of steranes. The analysis of the distribution of biomarkers suggests that the origin of the organic matter is dominated by terrestrial and marine plants, with a lower contribution of bacteria. The integration of stratigraphy and geochemistry suggests that the evolution of the early Aptian carbonate platform studied was the result of a combination of relative sea-level changes, leading to the initial progradational phase and the subsequent deposition of parasequences and, on the other hand, environmental changes reflected in the demise of the carbonate platform and the facies and faunal change recorded in the Agres bed. The OEA 1a took place after the drowning event, suggesting that the main environmental changes recorded in this section might be related to a combination of regional processes and the global changes predating and probably triggering the OAE1a. Acknowledgements: This work is a contribution of the research project CGL2009-10329.

Castro, J. M.; de Gea, G. A.; Ruiz-Ortiz, P. A.; Quijano, M. L.; Pancost, R. D.; Jimenez de Cisneros, C.; Caballero, E.

2012-04-01

244

Sedimentology of mid Permian strata of the Sublett Range, South-Central Idaho  

E-print Network

REGIONAL STRATIGRAPHY. 20 Park City Group. West-Central Utah, Northeastern Nevada, and South- Central Idaho. Kaibab Limestone Formation. Grandeur Formation vs. Grandeur Member. . . . . . . , . . . . . Grandeur Formation Plympton Formation Murdock... in Utah, Nevada, and south-central Idaho 23 Figure 8 Fence diagram showing distribution of Park City and Phosphoria Formations in southeastern Idaho and northeastern Utah. . . . . . . . . . . . . . . . . . . Figure 9 Diagramatic dip section...

Duree, Dana Kay

2012-06-07

245

Late Pleistocene Holocene stratigraphy and radiocarbon dating of La Malinche volcano, Central Mexico  

NASA Astrophysics Data System (ADS)

Previous studies of La Malinche identified and radiocarbon dated several volcanic layers, the youngest of which yielded an age of ca. 7.5 ka. An additional ash fallout layer that crops out at high altitudes was considered the most recent deposit, with an estimated age of 6 ka. In the present work 38 new radiocarbon ages are presented. From these, several date the young ash fallout layer and lie around 3.1 ka. With the aid of these dates a new and comprehensive stratigraphy documenting the Late Pleistocene-Holocene eruptive history of La Malinche is presented. The stratigraphy indicates two main stages of volcanic activity: Pre-Malinche and Malinche. The first undoubtedly comprises the major part of the eruptive history, but its deposits are largely covered by the products of the latter stage, on which this study is focused. The Malinche stage was subdivided into three eruptive periods. Period 1 started with the emplacement of the Huamantla Pumice more than 45 ka ago. This deposit consists of a thick pumice fallout overlain by pyroclastic flow deposits. Subsequently, several episodes of construction and collapse of summit domes occurred. The oldest dome was dated at ca. 45 ka. Period 2 started 21.5 ka ago with the Malinche Pumice I, a widespread pumice fallout covering the entire slopes of the volcano. Pyroclastic flows and lahars related to this eruption were channeled along deep barrancas and reached considerable distances. Deposits produced by partial sector collapse and dated at ca. 20.9 ka, and a pumice-and-ash flow deposit dated at 15.9 ka were also generated during this period. The last period started with the eruption of the Malinche Pumice II, a distinctive fallout deposit overlain by ash flow deposits on the NE slope of the volcano. The age of this pumice layer is estimated between 12 and 9 ka. Formation of block-and-ash flows, lahars and pumice-and-ash flows followed during this period, and peaked in a most intensive episode that was dated at 7.5 ka. After this, a long interval of quiescence was interrupted 3.1 ka ago, with the eruption of an ash fallout accompanied by small pyroclastic flows, whose deposits are the youngest volcanic products recognized at La Malinche. The new stratigraphic findings identify La Malinche as a potentially active and dangerous volcano that could severely affect densely populated areas at its lower slopes. In addition, the results of this work can shed some light on archaeological research that is being carried out in the Puebla-Tlaxcala region.

Castro-Govea, Renato; Siebe, Claus

2007-04-01

246

Stratigraphy of Atlantic coastal margin of United States north of Cape Hatteras; brief survey  

USGS Publications Warehouse

A synthesis of studies of sea-floor outcrops of the sedimentary wedge beneath the northeastern United States continental shelf and slope and a reassessment of coastal plain Mesozoic stratigraphy, particularly of the coastal margin, provide insight for estimating the oil and gas potential and provide geologic control for marine seismic investigations of the Atlantic continental margin. The oldest strata known to crop out on the continental slope are late Campanian in age. The Cretaceous-Tertiary contact along the slope ranges from a water depth of 0.6 to 1.5 km south of Georges Bank to 1.8 km in Hudson Canyon. Few samples are available from Tertiary and Late Cretaceous outcrops along the slope. Sediments of the Potomac Group, chiefly of Early Cretaceous age, constitute a major deltaic sequence in the emerged coastal plain. This thick sequence lies under coastal Virginia, Maryland, Delaware, southeastern New Jersey, and the adjacent continental shelf. Marine sands associated with this deltaic sequence may be present seaward under the outer continental shelf. South of the Norfolk arch, under coastal North Carolina, carbonate rocks interfinger with Lower Cretaceous clastic strata. From all available data, Mesozoic correlations in coastal wells between coastal Virginia and Long Island have been revised. The Upper-Lower Cretaceous boundary is placed at the transition between Albian and Cenomanian floras. Potential hydrocarbon source beds are present along the coast in the subsurface sediments of Cretaceous age. Potential reservoir sandstones are abundant in this sequence.

Perry, W.J.; Minard, J.P.; Weed, E.G.A.; Robbins, E.I.; Rhodehamel, E.C.

1975-01-01

247

Strontium isotopic, chemical, and sedimentological evidence for the evolution of Lake Lisan and the Dead Sea  

Microsoft Academic Search

Precise strontium isotope ratios, combined with chemical analyses and sedimentological information, are used to monitor the water sources and the evolution of the Dead Sea and its late Pleistocene precursor, Lake Lisan (70-18 kyr B.P.). The materials analyzed include bulk aragonite, water-leached soluble salts, and residual aragonite and gypsum from the Lisan Formation in the Perazim Valley (near the SW

M. Stein; A. Starinsky; A. Katz; S. L. Goldstein; M. Machlus; A. Schramm

1997-01-01

248

Sedimentological effects of tsunamis, with particular reference to impact-generated and volcanogenic waves  

Microsoft Academic Search

Impulse-generated waves (tsunamis) may be produced, at varying scales and global recurrence intervals (RI), by several processes. Meteorite-water impacts will produce tsunamis, and asteroid-scale impacts with associated mega-tsunamis may occur. A bolide-water impact would undoubtedly produce a major tsunami, whose sedimentological effects should be recognizable. Even a bolide-land impact might trigger major submarine landslides and thus tsunamis. In all posulated

Joanne Bourgeois; Patricia L. Wiberg

1988-01-01

249

Magnetic polarity stratigraphy and paleolatitude of the Triassic^Jurassic Blomidon Formation in the Fundy basin  

E-print Network

Magnetic polarity stratigraphy and paleolatitude of the Triassic^Jurassic Blomidon Formation form 7 April 2000; accepted 9 April 2000 Abstract A magnetic polarity stratigraphy is established for a continuously cored 360 m thick section of the entire cyclical lacustrine sequence and part of the sandy fluvial

Olsen, Paul E.

250

UTh stratigraphy of a cold seep carbonate crust , *, G.M. Hendersonb  

E-print Network

1 U­Th stratigraphy of a cold seep carbonate crust G. Bayona , *, G.M. Hendersonb & M. Bohnc, which provide the first stratigraphy for a cold-seep carbonate crust. The 5.5-cm thick crust (NL7-CC2 carbonate crust formation and the resulting reduction in bioirrigation. Overall, U­Th dating of cold seep

Paris-Sud XI, Université de

251

Integrating sequence stratigraphy and rock-physics to interpret seismic amplitudes and predict reservoir quality  

Microsoft Academic Search

This dissertation focuses on the link between seismic amplitudes and reservoir properties. Prediction of reservoir properties, such as sorting, sand\\/shale ratio, and cement-volume from seismic amplitudes improves by integrating knowledge from multiple disciplines. The key contribution of this dissertation is to improve the prediction of reservoir properties by integrating sequence stratigraphy and rock physics. Sequence stratigraphy has been successfully used

Tanima Dutta

2009-01-01

252

M.R. Saltzman and E. Thomas Chapter 11 Carbon Isotope Stratigraphy  

E-print Network

to date and correlate sediments. The stratigraphic record of carbon isotopes is complex because the main OF CARBON ISOTOPE STRATIGRAPHY The potential of marine carbonate d13 C trends and excursions to dateM.R. Saltzman and E. Thomas Chapter 11 Carbon Isotope Stratigraphy Abstract: Variations in the 13 C

Saltzman, Matthew R.

253

North polar stratigraphy and the paleo-erg of Mars Shane Byrne and Bruce C. Murray  

E-print Network

North polar stratigraphy and the paleo-erg of Mars Shane Byrne and Bruce C. Murray Division: Surface materials and properties; KEYWORDS: Mars, polar, geology, history, stratigraphy, dune 1 color and albedo values derived for the north polar dunes do not differ significantly from dark d

Byrne, Shane

254

A martian case study of segmenting images automatically for granulometry and sedimentology, Part 2: Assessment  

NASA Astrophysics Data System (ADS)

In a companion work, we bridge the gap between mature segmentation software used in terrestrial sedimentology and emergent planetary segmentation with an original algorithm optimized to segment whole images from the Microscopic Imager (MI) of the Mars Exploration Rovers (MER). In this work, we compare its semi-automated outcome with manual photoanalyses using unconsolidated sediment at Gusev and Meridiani Planum sites for geologic context. On average, our code and manual segmentation converge to within ?10% in the number and total area of identified grains in a pseudo-random, single blind comparison of 50 samples. Unlike manual segmentation, it also locates finer grains in an image with internal consistency, enabling robust comparisons across geologic contexts. When implemented in Mathematica-8, the algorithm segments an entire MI image within minutes, surpassing the extent and speed possible with manual segmentation by about a factor of ten. These results indicate that our algorithm enables not only new sedimentological insight from the MER MI data, but also detailed sedimentology with the Mars Science Laboratory’s Mars Hand Lens Instrument.

Karunatillake, Suniti; McLennan, Scott M.; Herkenhoff, Kenneth E.; Husch, Jonathan M.; Hardgrove, Craig; Skok, J. R.

2014-02-01

255

Sedimentological evolution in an UASB treating SYNTHES, a new representative synthetic sewage, at low loading rates.  

PubMed

The changes in the sedimentological attributes of the sludge bed in an upflow anaerobic sludge blanket (UASB) reactor fed with a low-strength wastewater mimicking raw domestic sewage were assessed in this study. The reactor was inoculated with 250 ml of granular sludge from a full-scale UASB reactor. The organic loading rate (OLR) varied from 1 to 2 g COD/ld. During the half-year long study, the reactor was operated at hydraulic retention times (HRTs) of 4.8 and 10 h, at 33 degrees C. Sludge sedimentology showed that the original granular sludge experienced serious instability and disintegration, leading to a much finer final grain assemblage, mainly due to substrate transfer limitation and cell starvation at the interior of larger granules. With time, the size uniformity tended to decrease, sphericity tended to increase, the skewness of the granule size distribution became negative, and the kurtosis became peaked and leptokurtic. In spite of the observed size reduction, reactor efficiency increased to a CODtotal removal of 96%. Biomass (sludge) yield was 0.012 g VS/g COD removed. The CH4 content of the biogas was high (up to 96%). This study thus highlights the treatment of a new type of wastewater with the deployment of the UASB reactor. It also reports the evolutionary trend of the biomass particle size distribution, making reference to a classic sedimentological appraisal. PMID:15062822

Aiyuk, Sunny; Verstraete, Willy

2004-07-01

256

Plio-Pleistocene cliff-bound, wedge-shaped, warm-temperate carbonate deposits from Rhodes (Greece): Sedimentology and facies  

NASA Astrophysics Data System (ADS)

The Pliocene to Pleistocene temperate carbonates of Rhodes were deposited in a tectonically active region, strongly influenced by a complicated and rapidly changing topography, provided by the highly tectonised late Cretaceous Lindos Limestone as basement rock. Deposition on this basement took place in accommodation loci restricted to micrograbens and their downslope extension, to the foot of steep submarine cliffs, to basement neptunian dykes and depressions in the basement rock. Consequently the sediments comprise a high degree of facies variability, and are typically thin and laterally discontinuous. The integration of several outcrops is necessary for the reconstruction of the stratigraphy and the relative sea-level changes. The sediments were deposited during a large-scale, tectonically driven transgressive-regressive cycle in water depths changing from zero to several hundreds of metres. At the studied Lindos-Pefkos Road cutting the Kolymbia Limestone, bound to the foot of Lindos Limestone cliffs, marks the onset of the marine deposition in the late Pliocene. Its fabric is a rudstone consisting of unsorted angular Lindos Limestone clasts (up to boulder-size) with a matrix dominated by molluscs and coralline algae. The overlying Plio-Pleistocene St. Paul's Bay Limestone consists of deep-water float- and rudstones containing the 'white coral community' dominated by the coral Lophelia pertusa. Its matrix shows a complex fabric of up to five sediment zones separated by differing states of lithification. In this maximum flooding phase, mineralised hardgrounds indicate depositional hiati. The subsequent shallowing phase is represented by the Cape Arkhangelos Calcarenite, a series of distinctive facies of very patchy distribution. They are characterised by the Bryozoan-Brachiopod Facies, overlain by a facies heavily dominated by the bivalve Mytilaster sp. ( Mytilaster Facies). Conspicuous for the Mytilaster Facies is the inverse, concave-up, stacking pattern of shelly material. This facies is followed by a serpulid framestone and associated serpulid rudstone. Neptunian dykes cut through the first two facies and are filled with an intraformational breccia grading into a breccia with abundant Mytilaster Facies clasts (Neptunian Dyke Facies). The sedimentology and interpretation of each facies include a description of the ichnology, in particular the bioerosion peculiar to each facies. The separation of different gravity transport processes in steep submarine environments is rarely described and most of the literature concentrates on siliciclastic-dominated coarse-grained, sandy or gravely sand delta environments. For a classification of the transport processes of the examined deposits, the following criteria were evaluated: sediment body symmetry, inclination of the palaeorelief, sediment constituents, fabric complexity, sedimentary structures and availability of fine matrix. Sedimentary structures and grading can be camouflaged in carbonates due to density differences of bioclasts; however bioclast-orientations such as bivalve stacking patterns can give information about the sedimentary process. We suggest the inverse, concave-up, stacking pattern of bivalve shells to be a texture potentially indicative for debris falls. Because of the above-mentioned criteria we classified the Kolymbia Limestone as rock-fall deposits and the St. Paul's Bay Limestone as well as the Mytilaster Facies of the Cape Arkhangelos Calcarenite as debris-fall deposits. The Bryozoan-Brachiopod Facies could not be classified with certainty because of the lack of sedimentary structures and bioclast-orientation. However, a grain-flow or most likely a debris-fall transport process seems probable.

Titschack, Jürgen; Bromley, Richard G.; Freiwald, André

2005-10-01

257

Elastic-Wavefield Seismic Stratigraphy: A New Seismic Imaging Technology  

SciTech Connect

The purpose of our research has been to develop and demonstrate a seismic technology that will provide the oil and gas industry a better methodology for understanding reservoir and seal architectures and for improving interpretations of hydrocarbon systems. Our research goal was to expand the valuable science of seismic stratigraphy beyond the constraints of compressional (P-P) seismic data by using all modes (P-P, P-SV, SH-SH, SV-SV, SV-P) of a seismic elastic wavefield to define depositional sequences and facies. Our objective was to demonstrate that one or more modes of an elastic wavefield may image stratal surfaces across some stratigraphic intervals that are not seen by companion wave modes and thus provide different, but equally valid, information regarding depositional sequences and sedimentary facies within that interval. We use the term elastic wavefield stratigraphy to describe the methodology we use to integrate seismic sequences and seismic facies from all modes of an elastic wavefield into a seismic interpretation. We interpreted both onshore and marine multicomponent seismic surveys to select the data examples that we use to document the principles of elastic wavefield stratigraphy. We have also used examples from published papers that illustrate some concepts better than did the multicomponent seismic data that were available for our analysis. In each interpretation study, we used rock physics modeling to explain how and why certain geological conditions caused differences in P and S reflectivities that resulted in P-wave seismic sequences and facies being different from depth-equivalent S-wave sequences and facies across the targets we studied.

Bob A. Hardage; Milo M. Backus; Michael V. DeAngelo; Sergey Fomel; Khaled Fouad; Robert J. Graebner; Paul E. Murray; Randy Remington; Diana Sava

2006-07-31

258

Base line sequence stratigraphy, Arkoma Basin to Chautauqua Arch  

SciTech Connect

Use of sequence stratigraphy concepts requires some caution, especially if these are based almost solely on theoretical models enhanced by a computer data base or by seismic records where lithologic interpretations are assumed rather than observed. Optimum input for sequence models is obtained from actual stratigraphic data from outcrops, cuttings and cores across sedimentary strike, such as those from the Arkoma Basin northward to the Chautauqua Arch along the Oklahoma-Kansas border area. Sequence stratigraphy involving Pennsylvanian data indicates a major northward shift of the Arkoma Basin paleobathymetric axis from the southern Ouachita Mountains to southern Kansas with some occasional backward and forward motion. This long base line is also needed to ascertain the total number of parasequences (transgressive-regressive cycles), their geometric succession, and interrelationship of low-stand, shelf-margin, transgressive high-stand, and condensed system tracks. The first two system tracts are important for productive reservoirs, whereas the latter three usually serve as prime source beds. Usually not all parasequences are present at any one place along an established base line or transect. The low-stand or shelf-margin parasequences are usually absent on the craton or on interbasinal or intrabasinal arches such as the Chautauqua Arch, whereas the transgressive and high-stand parasequences commonly thin basinward into condensed sequences or disappear through downlapping. Actual Pennsylvania outcrop data commonly differ from the standard sequence stratigraphy model of Exxon and Peter Vai. Sequence boundaries based on unconformities may occur at any place within a parasequence and may change places along the baseline.

Bennison, A.P.

1993-02-01

259

Stratigraphy and Observations of Nepthys Mons Quadrangle (V54), Venus  

NASA Technical Reports Server (NTRS)

Initial mapping has begun in Venus' Nepthys Mons Quadrangle (V54, 300-330 deg. E, 25-50 deg. S). Major research areas addressed are how the styles of volcanism and tectonism have changed with time, the evolution of shield volcanoes, the evolution of coronae, the characteristics of plains volcanism, and what these observations tell us about the general geologic history of Venus. Reported here is a preliminary general stratigraphy and several intriguing findings. Additional information is contained in the original extended abstract.

Bridges, N. T.

2001-01-01

260

Geoacoustic character, sedimentology and chronology of a cross-shelf Holocene sediment deposit off Cabo Frio, Brazil (southwest Atlantic Ocean)  

NASA Astrophysics Data System (ADS)

The Cabo Frio region in the state of Rio de Janeiro, southeast coast of Brazil, is characterized by a local coastal upwelling system and converging littoral sediment transport systems that are deflected offshore at Cabo Frio, as a consequence of which a thick cross-shelf sediment deposit has developed over time. To investigate the evolution of this muddy deposit, geophysical, sedimentological and geochemical data from four sediment cores (3.8-4.1 m in length) recovered in water depths between 88 and 141 m were analyzed. The high-resolution seismic data show variable sediment thicknesses ranging from 1 to 20 m, comprising two sedimentary units separated by a high-impedance layer at a depth of about 10 m below the seafloor at the coring sites. According to the available age datings, the upper sedimentary unit is late Pleistocene to Holocene in age, whereas the lower unit (not dated) must, by implication, be entirely Pleistocene in age. The boomer-seismic reflection signal can be divided into three echo-types, namely transparent (inner shelf), stratified (middle shelf) and reflective (outer shelf), each type seemingly related to the local sediment composition. The upper 4 m of the upper sedimentary unit is dominated by silty sediment on the middle shelf, and by upward-fining sediments (silty sand to sandy silt) on the inner and outer shelf. The downcore trends of P-wave velocity, gamma-ray density and acoustic impedance are largely similar, but generally reversed to those of water and organic carbon contents. Total organic carbon contents increase with decreasing mean grain size, periodic fluctuations suggesting temporal changes in the regional hydrodynamics and primary productivity fuelled by the local upwelling system. The reconstruction of sedimentation rates in the course of the Holocene is based on 35 AMS age datings of organic material recovered from variable downcore depths. These range from a maximum of 13.3 cm/decade near the base of the inner shelf core (7.73-7.70 ka BP) to generally very low values (<0.11 cm/century) over the last thousand years in all cores. Over the last 6 ka there appear to have been three distinct sedimentation peaks, one between 6 and 5 ka BP, another between 4 and 3 ka PB, and one around 1 ka BP. Due to different time intervals between dates, not every peak is equally well resolved in all four cores. Based on the similar sedimentology of the inner and outer shelf cores, an essentially identical sedimentation model is proposed to have been active in both cases, albeit at different times. Thus, already during the last glacial maximum, alongshore sediment transport was deflected offshore by a change in shoreline orientation caused by the Cabo Frio structural high. The source of terrigenous material was probably a barrier-island complex that was subsequently displaced landward in the course of sea-level rise until it stabilized some 6.5 ka BP along the modern coast.

Mendoza, Ursula; Ayres Neto, Arthur; C. Abuchacra, Rodrigo; Fernandes Barbosa, Cátia; G. Figueiredo, Alberto; C. Gomes, Manoela; Belem, Andre L.; Capilla, Ramsés; S. Albuquerque, Ana Luiza

2014-08-01

261

Contributions to the stratigraphy of southwestern Colorado  

USGS Publications Warehouse

In the course of field work of the United States Geological Survey in the San Juan region of Colorado observations have been made in the last three seasons that considerably extend our knowledge of the great stratigraphic break below the La Plata sandstone, which is currently assumed to be of Jurassic age. The new data pertain partly to the relations existing in the Gunnison Valley, north of the San Juan Mountains, where the unconformity marking this break was already known at certain places, and partly to the conditions in the Piedra Valley, on the south side of the mountains, where the unconformity had not before been noted. The Piedra Valley is of special interest, and it seems well to call attention to the relations observed even though they were examined only in a reconnaissance. The first part of this paper is devoted to the evidence of the overlap of the La Plata sandstone; the second to the stratigraphic relations in the Piedra Valley. The section of sedimentary formations in Piedra Canyon is of much interest because none of the pre-La Plata formations are known east of this locality on the south side of the San Juan Mountains. Most of these formations exhibit a notably different facies where they reappear from beneath the overlying beds at their nearest exposures in New Mexico, southeast of the Piedra Valley. It is believed that the character of the formations in the Piedra section should be recorded for the benefit of geologists who may be studying the Paleozoic and Mesozoic rocks of New Mexico, and accordingly the second part of the paper presents details of the structure and the stratigraphic section of Piedra Valley.

Cross, Whitman; Larsen, E.S., Jr.

1915-01-01

262

Cover sequence stratigraphy and structure: Salem Church basement culmination, Georgia Blue Ridge  

SciTech Connect

The Salem Church anticline SW of Jasper, Georgia in the western Blue Ridge is roughly an oval shaped structural dome with its long axis trending NE-SW. The anticline is cored by the Grenville age Corbin Gneiss which represents allochthonous North American basement. In debate for decades has been the age and origin of several kilometers of poly-deformed cover sequence rocks which were metamorphosed to greenschist facies and were probably transported over a long distance inland after their deposition. The stratigraphy of the cover sequence exhibits rapid lithofacies changes. At most localities, the basement is overlain by a 500--600 m thick coarse clastic unit sourced from the basement rocks, composed mainly of metaconglomerate, metasandstone and metadiamictite. A thin unit less than 20 m thick of sericite phyllite occurs between the basement and the coarse clastic unit along the SE limb of the anticline but pinches out to the MW. A relatively sharp stratigraphic contact occurs between quartzite unit and overlying dark colored metagreywackes and metadiamictites containing distinctive cobbles and boulders of granitic and gneissic basement rocks up to 1 meter in length. This unit is about 100 m thick in the SW but thins rapidly towards the NE. It grades up into a geographically widespread graphitic phyllite which encircles most of the anticline. Unlike the cover sequence above the corbin basement west of Waleska, Georgia, no carbonate is found in this area.

Li, L.; Tull, J.F. (Florida State Univ., Tallahassee, FL (United States). Dept. of Geology)

1994-03-01

263

The Middle to Upper Paleolithic transition: dating, stratigraphy, and isochronous markers.  

PubMed

Accurate and precise dating is vital to our understanding of the Middle to Upper Paleolithic transition. There are, however, a number of uncertainties in the chronologies currently available for this period. We attempt to examine these uncertainties by utilizing a number of recent developments in the field. These include: the precise dating of the Campanian Ignimbrite (CI) tephra by 40Ar/39Ar; the tracing of this tephra to a number of deposits that are radiocarbon dated; the publication of revised radiocarbon calibration data for the period, showing a much better convergence with other available data than during the recent IntCal comparison; and a layer-counted ice-core chronology extending beyond 40,000cal BP. Our data comparisons suggest that a reasonable overall convergence between calibrated radiocarbon ages and calendar dates is possible using the new curves. Additionally, we suggest that charcoal-based radiocarbon ages, as well as bone-based radiocarbon determinations, require cautious interpretation in this period. Potentially, these issues extend far beyond the sites in this study and should be of serious concern to archaeologists studying the Middle to Upper Paleolithic. We conclude by outlining a strategy for moving the science forward by a closer integration of archaeology, chronology, and stratigraphy. PMID:18926557

Blockley, S P E; Ramsey, C Bronk; Higham, T F G

2008-11-01

264

The Department of Geology at Wayne State University consists of five full-time faculty and five  

E-print Network

(Geochemistry and Geophysics), Jeffrey Howard (Sedimentology), Larry Lemke (Hydrogeology), and Ed van Hees faculty are conducting research in the general areas of Sedimentology, Stratigraphy, Soil Science

Baskaran, Mark

265

The Department of Geology at Wayne State University consists of five full-time faculty and five  

E-print Network

(Geochemistry and Geophysics), Jeffrey Howard (Sedimentology), Larry Lemke (Hydrogeology), and Ed van Hees conduct research in the general areas of Sedimentology, Stratigraphy, Soil Science, Hydrogeology

VandeVord, Pamela

266

146 Earth Science 147 Earth Science  

E-print Network

Sedimentology ESCI 334 Geological and Geophysical Techniques ESCI 390 Field Geology ESCI 442 Exploration geology and paleoceanography, stratigraphy, carbonate and siliciclastic sedimentology, igneous petrology

Richards-Kortum, Rebecca

267

Program of Study Research Facilities  

E-print Network

state-of-the-art stable isotope laboratory, climatology laboratory, sedimentology laboratory, geological geology, quaternary stratigraphy, and sedimentology. Harold W. Borns, Jr., Ph.D. (Boston University, 1959

Thomas, Andrew

268

Cenozoic stratigraphy of the Sahara, Northern Africa  

USGS Publications Warehouse

This paper presents an overview of the Cenozoic stratigraphic record in the Sahara, and shows that the strata display some remarkably similar characteristics across much of the region. In fact, some lithologies of certain ages are exceptionally widespread and persistent, and many of the changes from one lithology to another appear to have been relatively synchronous across the Sahara. The general stratigraphic succession is that of a transition from early Cenozoic carbonate strata to late Cenozoic siliciclastic strata. This transition in lithology coincides with a long-term eustatic fall in sea level since the middle Cretaceous and with a global climate transition from a Late Cretaceous–Early Eocene “warm mode” to a Late Eocene–Quaternary “cool mode”. Much of the shorter-term stratigraphic variability in the Sahara (and even the regional unconformities) also can be correlated with specific changes in sea level, climate, and tectonic activity during the Cenozoic. Specifically, Paleocene and Eocene carbonate strata and phosphate are suggestive of a warm and humid climate, whereas latest Eocene evaporitic strata (and an end-Eocene regional unconformity) are correlated with a eustatic fall in sea level, the build-up of ice in Antarctica, and the appearance of relatively arid climates in the Sahara. The absence of Oligocene strata throughout much of the Sahara is attributed to the effects of generally low eustatic sea level during the Oligocene and tectonic uplift in certain areas during the Late Eocene and Oligocene. Miocene sandstone and conglomerate are attributed to the effects of continued tectonic uplift around the Sahara, generally low eustatic sea level, and enough rainfall to support the development of extensive fluvial systems. Middle–Upper Miocene carbonate strata accumulated in northern Libya in response to a eustatic rise in sea level, whereas Upper Miocene mudstone accumulated along the south side of the Atlas Mountains because uplift of the mountains blocked fluvial access to the Mediterranean Sea. Uppermost Miocene evaporites (and an end-Miocene regional unconformity) in the northern Sahara are correlated with the Messinian desiccation of the Mediterranean Sea. Abundant and widespread Pliocene paleosols are attributed to the onset of relatively arid climate conditions and (or) greater variability of climate conditions, and the appearance of persistent and widespread eolian sediments in the Sahara is coincident with the major glaciation in the northern hemisphere during the Pliocene.

Swezey, Christopher S.

2009-01-01

269

Perspective on the sequence stratigraphy of continental strata  

SciTech Connect

This report is the result of a working group on continental sequence stratigraphy that was set up at the 1991 NUNA conference in Banff, Canada. To data, sequence stratigraphic concepts have been applied mainly to the marine realm, but unconformity-bounded units have long been recognized in nonmarine strata. Successful application of sequence stratigraphic concepts to continental strata requires careful consideration of controls on base level and sediment supply. As with shallow marine environments, relative sea level can be considered as the stratigraphic as well as the geomorphic base level for coastal nonmarine settings. Farther inland, stratigraphic base level, which determines accomodation space, is more complex and takes various forms, such as the graded profile for fluvial strata, groundwater tables for some eolian strata, and lake level for some intermontane sediments. Sediment supply is also generally a more complex variable for nonmarine environments than in the marine realm because of the proximity to the source area. The influence of climate and tectonism on sediment supply can clearly be seen in many continental sediments. Although in its infancy, sequence stratigraphy concepts have been applied to a wide variety of continental settings in attempts to explain variations in facies architecture. Future advances in this field promise tools for more precise correlation of nonmarine strata and better prediction of the location and geometry of facies from a limited knowledge of the stratigraphic relationships within a basin. This would be useful in the exploration for fluvial and eolian sandstone reservoirs and coalbeds. 135 refs., 13 figs.

Shanley, K.W. (Shell Development Company, Houston, TX (United States)); McCabe, P.J. (Geological Survey, Denver, CO (United States))

1994-04-01

270

Sequence stratigraphy on an early Cretaceous passive margin, Exmouth Plateau  

SciTech Connect

Permian-Jurassic rifting of northwestern Australia resulted in the development of a passive continental margin flanking the northeastern Indian Ocean. On this margin the relatively thin synrift to postrift sedimentary sequence of southern Exmouth Plateau was drilled during ODP Leg 122. A sequence-stratigraphy analysis of the complete Mesozoic-Cenozoic sedimentary succession at Sites 762 and 763 was derived from a synthesis of seismic stratigraphy, wireline logs, lithostratigraphy, biostratigraphy, and magnetostratigraphy. Results indicate that during breakup, the southern Exmouth Plateau was a transform margin with an extensional component. Between the Tithonian and Valanginian, a thick clastic wedge prograded from the transform margin south of Site 763 northwestward toward Site 762 and onto subsiding continental crust. Southern clastic supply decreased into the Aptian-Cenomanian, and cyclic deposition of deep-water mudstones continued during subsidence of the earlier shelf margin wedge. Between the Albian and Cenomanian, deposition gradually became dominated by pelagic carbonates. Two regional unconformities mark the Cenomanian/Turonian and Cretaceous/Tertiary boundaries. Each was an erosional event, succeeded by renewed pelagic carbonate deposition that began in the distal northern basin and onlapped progressively toward the topographic high, which persisted into the Tertiary along the southern margin. The entire Jurassic to Holocene record at the southern Exmouth Plateau ODP sites is less than 1500 m thick and represents a classic rift to mature ocean passive-margin succession.

Boyd, R.; Gorur, N.; Ito, M.; O'Brien, D.; Wilkens, R.; Tang, C.

1989-03-01

271

Fluctuating Mesozoic and Cenozoic sea levels and implications for stratigraphy  

SciTech Connect

Sequence stratigraphy encompasses depositional models of genetically related packages of sediments deposited during various phases of cycle of sea level change, i.e., from a lowstand to highstand to the subsequent lowstand. The application of these models to marine outcrops around the world and to subsurface data led to the construction of Mesozoic-Cenozoic sea level curves with greater event resolution than the earlier curves based on seismic data alone. Construction of these better resolution curves begins with an outline of the principles of sequence-stratigraphic analysis and the reconstruction of the history of sea level change from outcrop and subsurface data for the past 250 Ma. Examples of marine sections from North America, Europe, and Asia can be used to illustrate sequence analysis of outcrop data and the integration of chronostratigraphy with sea level history. Also important are the implications of sequence-stratigraphic methodology and the new cycle charts to various disciplines of stratigraphy, environmental reconstruction, and basin analysis. The relationship of unconformities along the continental margins to hiatuses and dissolution surfaces in the deep basins must also be explored, as well as the relevance of sequence-stratigraphic methodology to biofacies and source rock prediction.

Haq, B.U. (National Science Foundation, Washington, DC (USA))

1988-12-01

272

North polar region of Mars: Advances in stratigraphy, structure, and erosional modification  

USGS Publications Warehouse

We have remapped the geology of the north polar plateau on Mars, Planum Boreum, and the surrounding plains of Vastitas Borealis using altimetry and image data along with thematic maps resulting from observations made by the Mars Global Surveyor, Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter spacecraft. New and revised geographic and geologic terminologies assist with effectively discussing the various features of this region. We identify 7 geologic units making up Planum Boreum and at least 3 for the circumpolar plains, which collectively span the entire Amazonian Period. The Planum Boreum units resolve at least 6 distinct depositional and 5 erosional episodes. The first major stage of activity includes the Early Amazonian (???3 to 1 Ga) deposition (and subsequent erosion) of the thick (locally exceeding 1000 m) and evenly-layered Rupes Tenuis unit (Abrt), which ultimately formed approximately half of the base of Planum Boreum. As previously suggested, this unit may be sourced by materials derived from the nearby Scandia region, and we interpret that it may correlate with the deposits that regionally underlie pedestal craters in the surrounding lowland plains. The second major episode of activity during the Middle to Late Amazonian (??? <1 Ga) began with a section of dark, sand-rich and light-toned ice-rich irregularly-bedded sequences (Planum Boreum cavi unit, Abbc) along with deposition of evenly-bedded light-toned ice- and moderate-toned dust-rich layers (Planum Boreum 1 unit, Abb1). These units have transgressive and gradational stratigraphic relationships. Materials in Olympia Planum underlying the dunes of Olympia Undae are interpreted to consist mostly of the Planum Boreum cavi unit (Abbc). Planum Boreum materials were then deeply eroded to form spiral troughs, Chasma Boreale, and marginal scarps that define the major aspects of the polar plateau's current regional topography. Locally- to regionally-extensive (though vertically minor) episodes of deposition of evenly-bedded, light- and dark-toned layered materials and subsequent erosion of these materials persisted throughout the Late Amazonian. Sand saltation, including dune migration, is likely to account for much of the erosion of Planum Boreum, particularly at its margin, alluding to the lengthy sedimentological history of the circum-polar dune fields. Such erosion has been controlled largely by topographic effects on wind patterns and the variable resistance to erosion of materials (fresh and altered) and physiographic features. Some present-day dune fields may be hundreds of kilometers removed from possible sources along the margins of Planum Boreum, and dark materials, comprised of sand sheets, extend even farther downwind. These deposits also attest to the lengthy period of erosion following emplacement of the Planum Boreum 1 unit. We find no evidence for extensive glacial flow, topographic relaxation, or basal melting of Planum Boreum materials. However, minor development of normal faults and wrinkle ridges may suggest differential compaction of materials across buried scarps. Timing relations are poorly-defined mostly because resurfacing and other uncertainties prohibit precise determinations of surface impact crater densities. The majority of the stratigraphic record may predate the recent (<20 Ma) part of the orbitally-driven climate record that can be reliably calculated. Given the strong stratigraphic but loose temporal constraints of the north polar geologic record, a comparison of north and south polar stratigraphy permits a speculative scenario in which major Amazonian depositional and erosional episodes driven by global climate activity is plausible. ?? 2008 Elsevier Inc. All rights reserved.

Tanaka, K.L.; Rodriguez, J.A.P.; Skinner, J.A., Jr.; Bourke, M.C.; Fortezzo, C.M.; Herkenhoff, K.E.; Kolb, E.J.; Okubo, C.H.

2008-01-01

273

North polar region of Mars: Advances in stratigraphy, structure, and erosional modification  

NASA Astrophysics Data System (ADS)

We have remapped the geology of the north polar plateau on Mars, Planum Boreum, and the surrounding plains of Vastitas Borealis using altimetry and image data along with thematic maps resulting from observations made by the Mars Global Surveyor, Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter spacecraft. New and revised geographic and geologic terminologies assist with effectively discussing the various features of this region. We identify 7 geologic units making up Planum Boreum and at least 3 for the circumpolar plains, which collectively span the entire Amazonian Period. The Planum Boreum units resolve at least 6 distinct depositional and 5 erosional episodes. The first major stage of activity includes the Early Amazonian (˜3 to 1 Ga) deposition (and subsequent erosion) of the thick (locally exceeding 1000 m) and evenly-layered Rupes Tenuis unit (A Brt), which ultimately formed approximately half of the base of Planum Boreum. As previously suggested, this unit may be sourced by materials derived from the nearby Scandia region, and we interpret that it may correlate with the deposits that regionally underlie pedestal craters in the surrounding lowland plains. The second major episode of activity during the Middle to Late Amazonian ( ˜<1 Ga) began with a section of dark, sand-rich and light-toned ice-rich irregularly-bedded sequences (Planum Boreum cavi unit, A Bb c) along with deposition of evenly-bedded light-toned ice- and moderate-toned dust-rich layers (Planum Boreum 1 unit, A Bb 1). These units have transgressive and gradational stratigraphic relationships. Materials in Olympia Planum underlying the dunes of Olympia Undae are interpreted to consist mostly of the Planum Boreum cavi unit (A Bb c). Planum Boreum materials were then deeply eroded to form spiral troughs, Chasma Boreale, and marginal scarps that define the major aspects of the polar plateau's current regional topography. Locally- to regionally-extensive (though vertically minor) episodes of deposition of evenly-bedded, light- and dark-toned layered materials and subsequent erosion of these materials persisted throughout the Late Amazonian. Sand saltation, including dune migration, is likely to account for much of the erosion of Planum Boreum, particularly at its margin, alluding to the lengthy sedimentological history of the circum-polar dune fields. Such erosion has been controlled largely by topographic effects on wind patterns and the variable resistance to erosion of materials (fresh and altered) and physiographic features. Some present-day dune fields may be hundreds of kilometers removed from possible sources along the margins of Planum Boreum, and dark materials, comprised of sand sheets, extend even farther downwind. These deposits also attest to the lengthy period of erosion following emplacement of the Planum Boreum 1 unit. We find no evidence for extensive glacial flow, topographic relaxation, or basal melting of Planum Boreum materials. However, minor development of normal faults and wrinkle ridges may suggest differential compaction of materials across buried scarps. Timing relations are poorly-defined mostly because resurfacing and other uncertainties prohibit precise determinations of surface impact crater densities. The majority of the stratigraphic record may predate the recent (<20 Ma) part of the orbitally-driven climate record that can be reliably calculated. Given the strong stratigraphic but loose temporal constraints of the north polar geologic record, a comparison of north and south polar stratigraphy permits a speculative scenario in which major Amazonian depositional and erosional episodes driven by global climate activity is plausible.

Tanaka, Kenneth L.; Rodriguez, J. Alexis P.; Skinner, James A.; Bourke, Mary C.; Fortezzo, Corey M.; Herkenhoff, Kenneth E.; Kolb, Eric J.; Okubo, Chris H.

2008-08-01

274

Volcanic stratigraphy of the Barrel Springs--Wild Cherry Formations, Davis Mountains, Trans-Pecos Texas  

SciTech Connect

Detailed mapping, stratigraphy, [sup 40]Ar/[sup 39]Ar ages, and geochemistry allow, for the first time, a coherent volcanic history of the Barrel Springs--Wild Cherry (BS-WC) units, the most widespread of the Davis Mountains volcanic field (DMVF). These units erupted dominantly from the [approximately] 20 km-diameter Paradise Mountain caldera (PMC), in the west-central DMVF, where thick, locally silicified and kaolinized intracaldera tuffs and interbedded lavas were resurgently domed by an 8 x 5-km-diameter syenitic intrusion. BS-WC units, all rhyolites, consist dominantly of a lower, moderately porphyritic ash-flow tuff; a petrographically similar, middle ash-flow tuff; and an upper group of voluminous, abundantly porphyritic lavas. The lower ash-flow tuff is strongly rheomorphic throughout its occurrence. The middle ash-flow is also rheomorphic in thick outcrops near the PMC but not in thin ([<=]10m), distal outcrops. These three units are interbedded with lavas lithologically similar to the tuffs near the PMC and with volcaniclastic sedimentary rocks in more distal area. The two ash-flow tuffs are separated by strongly porphyritic trachyte lavas of the Mount Locke Formation in the vicinity of the PMC. Sources and extents of individual flows of the upper lavas have not been positively identified. [sup 40]Ar/[sup 39]Ar ages of alkali feldspar phenocrysts from thirteen samples constrain most BS-WC to a 300 ka span. The lower tuff erupted about 35.6 Ma. The middle tuff and part of the voluminous lava package erupted at 35.3 Ma. Ages of two lavas are 35.1 Ma, which suggests prolonged eruption. Correlations based on lithology and age relations are supplemented by trace element and mineral studies that confirm close geochemical affinities.

Parker, D.F. (Baylor Univ., Waco, TX (United States). Dept. Geology); Henry, C.D. (Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology); Kunk, M.J. (Geological Survey, Reston, VA (United States))

1993-02-01

275

Geomorphological and sedimentological record of accelerated deglaciation of small mountain glacier, Ragnarbreen, Svalbard  

NASA Astrophysics Data System (ADS)

Most of the Svalbrad glaciers have been in retreat since the end of the Little Ice Age (LIA). Hence, they give a good opportunity to study the geomorphological and sedimentological record of deglaciation. The aim of the study is to describe main landsystem elements of Ragnar glacier and relate them to different stages of the glacier recession. The Ragnar glacier is located in the Svalbard archipelago, in the central part of the West Spitsbergen Isle, in the north branch of Billefjorden. Ragnar is a small (~ 6 km2), outlet glacier, which current clean ice edge has retreated ca. 1500 m from the position related to the maximum LIA extent. Fieldworks of the study comprised detailed geomorphological mapping and sedimentary works. Four main elements of the landsystem of the Ragnar glacier can be distinguished: 1) Clean glacier surface. Currently, the ice surface of Ragnar glacier is almost completely debris-free and with only several supraglacial streams. 2) Ice-marginal lake. The lake started to form after 1980 year. Since that time, its length has reached 1000 m. Distant (from the ice-edge) part of the lake is shallow (< 2 m) with several small islands. Part proximal to the current ice edge is deeper (up to 16 m) and devoid of islands. At the bottom of the lake some ice (probable of glacier origin) was detected. 3) Lateral moraines - were developed along the both valley sides, from frontal moraine complex - to ca. 2 km upward the glacier valley. 4) Frontal moraine complex. This complex comprises of several chains of ridges and depressions and is relatively distinct - elevated about 35 m above the valley bottom. The elements of the landsystem of the Ragnar glacier have undergone several transformations since the LIA maximum: 1) Formation of the frontal moraine complex can be related to the state of dynamic equilibrium of the glacier during the LIA maximum. During formation of the complex and shortly after it the main depositional agents were intense debris flows, which are recorded by thick covers of the old debris flow deposits. Nowadays, despite of ice-cores, frontal moraine complex is much more stable than the lateral moraines or ice-marginal lake. 2) As a consequence of lowering of the clean glacier surface and formation of the distinct lateral moraines, the debris delivering from the valley sides is limited only to very narrow zone of the glacier (i.e. only to the lateral moraine). 3) Accelerated recession of the ice mouth and limitation in delivery of debris from sides of the valley caused that amount of deposits released in the ice front is small. 4) Increasing amount of water flowing from the glacier was blocked by frontal moraine complex and the ice marginal lake was created. 5) The debris cover on the lateral moraines is relatively thin. In addition, as a consequence of the clean ice surface lowering, slopes of the lateral moraines are very steep. It causes that mass movement processes (especially debris flows) are ubiquitous. Contemporary, lateral moraines are the elements undergoing the most intense transformations. Observations made in the Ragnar marginal zone revealed spatial-temporal changes in distribution of the sediments and landforms. They also add some premises that in the first stage of deglaciation debris flow and other mass wasting processes are most common. In the later phase glaciolacustrine and glaciofluvial deposition also plays important role in transformation of landforms and sediments.

Ewertowski, Marek

2010-05-01

276

Sedimentological Investigations of the Martian Surface using the Mars 2001 Robotic Arm Camera and MECA Optical Microscope  

NASA Technical Reports Server (NTRS)

The first microscopic sedimentological studies of the Martian surface will commence with the landing of the Mars Polar Lander (MPL) December 3, 1999. The Robotic Arm Camera (RAC) has a resolution of 25 um/p which will permit detailed micromorphological analysis of surface and subsurface materials. The Robotic Ann will be able to dig up to 50 cm below the surface. The walls of the trench will also be inspected by RAC to look for evidence of stratigraphic and / or sedimentological relationships. The 2001 Mars Lander will build upon and expand the sedimentological research begun by the RAC on MPL. This will be accomplished by: (1) Macroscopic (dm to cm): Descent Imager, Pancam, RAC; (2) Microscopic (mm to um RAC, MECA Optical Microscope (Figure 2), AFM This paper will focus on investigations that can be conducted by the RAC and MECA Optical Microscope.

Rice, J. W., Jr.; Smith, P. H.; Marshall, J. R.

1999-01-01

277

Sedimentology and diagenesis of windward-facing fore-reef calcarenites, Late Pleistocene of Barbados, West Indies  

SciTech Connect

Late Pleistocene reef terraces in southeastern Barbardos developed extensive fore-reef sand facies during deposition in response to high-energy windward-facing conditions. Sedimentology and diagenesis of these deposits illustrate significant contrasts with previous studies from the leeward west coast. These calcarenites are dominantly skeletal packstones with less common grainstones and wackestones present. The fore-reef sand facies occurs within progradational reef sequences, being conformably overlain by deep-water head coral facies. Medium-bedded, laterally continuous sand sheets retain original depositional slopes, dipping seaward at 10/degrees/-15/degrees/. These fore-reef deposits, in places, are over 30 m thick (average 20 m) and developed rapidly during late Pleistocene glacio-eustatic sea level highstands. Sedimentation rate ranges from 2 to 5 m/1000 years. Areal extent of fore-reef calcarenites in southeastern Barbados is estimated to be 8-10 km/sup 2/. Lithologically, the packstones are composed of an abundance of coralline red algae and the benthic foraminifer Amphistegina sp. Other volumetrically significant allochems include echinoids, mollusks, rhodoliths, peloids, and micritized grains. Micrite in the wackestone and packstone lithologies is likely derived from intense physical/mechanical abrasion of shoal-water reef facies. Diagenesis of these lithologies reflects a complex interplay of meteoric, mixing zone, and marine environments as a result of glacio-eustasy. Differences in diagenetic character are derived from differences in terrace ages, terrace geometry, a paleotopographic control on meteoric ground-water distribution, and high-energy coastal conditions. Diagenetic fabrics include equant, blocky meteoric phreatic calcite; limpid dolomite of mixing zone origin: and peloidal and isopachous fibrous cements from marine precipitation.

Humphrey, J.D.; Kimbell, T.N.

1989-03-01

278

Pre-Wisconsin glacial stratigraphy of the central plains region in Iowa, Nebraska, Kansas, and Missouri  

NASA Astrophysics Data System (ADS)

SummaryRecent investigations have documented the presence of several tills and interglacial paleosols that were not recognized in the simple Kansan—Aftonian—Nebraskan stratigraphic sequence. Also, the single 'Pearlette ash' recognized by early workers now is known to be three different Pearlette family ash beds of greatly contrasting ages. The complexity of the stratigraphy, as it is currently understood, and the miscorrelations of early work necessitate abandonment of the archaic terms Kansan, Aftonian, and Nebraskan in stratigraphic terminology. Continued use of those terms will only promote confusion of stratigraphic nomenclature and erroneous correlations of stratigraphic units. The limited chronometric control available within the early and middle Pleistocene stratigraphic sequence is provided directly by dating or by correlation of buried soils and volcanic ash beds and it is provided inferentially by interpretation of magnetic polarity data. These controls provide, at best, a general time framework to begin a new synthesis of the Quaternary history of the region. New methods of dating are needed to facilitate long-distance correlation of early and middle Pleistocene deposits.

Hallberg, George R.

279

La stratigraphie oligo-miocène et la surface d'érosion messinienne en mer Noire, stratigraphie sismique haute résolutionThe Oligo-Miocene stratigraphy and the Messinian erosional surface in Black Sea, high-resolution seismic stratigraphy  

NASA Astrophysics Data System (ADS)

The stratigraphy of the Black Sea western margin is revisited through seismic data acquired during two French-Romanian surveys. These data are calibrated by industrial and DSDP drillings; they display several major discontinuities regarded as Tertiary erosional surfaces. The major seismic discontinuity underlines the base of Miocene formations and corresponds to a composite surface including at least three erosional phases ranging from Oligocene to Pontian times. Moreover, a Messinian erosional surface is clearly identified. This is in agreement with the Hsü's proposition [Palaeogeogr. Palaeoclimatol. Palaeoecol. 29 (1979) 75-93] suggesting a Messinian sea-level drop of Black Sea related to the Messinian Salinity Crisis described in the Mediterranean Sea. To cite this article: H. Gillet et al., C. R. Geoscience 335 (2003).

Gillet, Hervé; Lericolais, Gilles; Rehault, Jean-Pierre; Dinu, Corneliu

2003-10-01

280

Phaneorozoic sequence stratigraphy of Bolivia and adjacent regions  

SciTech Connect

Phaneorozoic sequence stratigraphy of the Pacific margin of western South America, particularly the Bolivian section, has been completed and new interpretations and hypotheses have been proposed as a result of data analyses of this information. The Paleozoic margin was initially passive (late Cambrian-Llanvirn, [open quotes]Puna aulacogen[close quotes]), but became active during a middle Ordovician compressional episode. Most of late Cambrian to early Triassic Bolivian rocks are of marine origin, with dark shale units recording sea level rises, whereas middle Triassic to Recent rocks were mainly deposited in continental environments (except six restricted-marine ingressions in the late Cretaceous-Danian, and one in the late Miocene, all with hydrocarbon potential). A noteworthy similarity exists between the Devonian to Jurassic stratigraphies of Bolivia and the Parana basin, suggesting that Bolivia behaved as part of the Brazilian craton from late Cambrian to late Jurassic, when it was captured into the Pacific margin geotectonic system. Organic-rich units correlate with Paleozoic highstand deposits and younger ingressions. The Bolivian Phanerozoic strata is characterized by thick layers, partly due to middle Ordovician-Carboniferous and late Cretaceous-Cenozoic foreland basins. Paleozoic foreland geometries include northeastern onlaps and, potentially, stratigraphic traps. Hydrocarbon generation, migration and trapping mainly depended on Cenozoic structural loading and burial and on propagation of Andean deformation which are comprised of Paleozoic shale decollements. Precise knowledge of the evolution of the Phanerozoic geodynamic contexts and basin geometries through sedimentation and subsequent deformations is crucial for hydrocarbon exploration strategies in these regions.

Sempere, T. (Convenio YPFB-Orstom, Santa Cruz (Bolivia))

1993-02-01

281

Integrated sequence stratigraphy of the postimpact sediments from the Eyreville core holes, Chesapeake Bay impact structure inner basin  

USGS Publications Warehouse

The Eyreville core holes provide the first continuously cored record of postimpact sequences from within the deepest part of the central Chesapeake Bay impact crater. We analyzed the upper Eocene to Pliocene postimpact sediments from the Eyreville A and C core holes for lithology (semiquantitative measurements of grain size and composition), sequence stratigraphy, and chronostratigraphy. Age is based primarily on Sr isotope stratigraphy supplemented by biostratigraphy (dinocysts, nannofossils, and planktonic foraminifers); age resolution is approximately ??0.5 Ma for early Miocene sequences and approximately ??1.0 Ma for younger and older sequences. Eocene-lower Miocene sequences are subtle, upper middle to lower upper Miocene sequences are more clearly distinguished, and upper Miocene- Pliocene sequences display a distinct facies pattern within sequences. We recognize two upper Eocene, two Oligocene, nine Miocene, three Pliocene, and one Pleistocene sequence and correlate them with those in New Jersey and Delaware. The upper Eocene through Pleistocene strata at Eyreville record changes from: (1) rapidly deposited, extremely fi ne-grained Eocene strata that probably represent two sequences deposited in a deep (>200 m) basin; to (2) highly dissected Oligocene (two very thin sequences) to lower Miocene (three thin sequences) with a long hiatus; to (3) a thick, rapidly deposited (43-73 m/Ma), very fi ne-grained, biosiliceous middle Miocene (16.5-14 Ma) section divided into three sequences (V5-V3) deposited in middle neritic paleoenvironments; to (4) a 4.5-Ma-long hiatus (12.8-8.3 Ma); to (5) sandy, shelly upper Miocene to Pliocene strata (8.3-2.0 Ma) divided into six sequences deposited in shelf and shoreface environments; and, last, to (6) a sandy middle Pleistocene paralic sequence (~400 ka). The Eyreville cores thus record the fi lling of a deep impact-generated basin where the timing of sequence boundaries is heavily infl uenced by eustasy. ?? 2009 The Geological Society of America.

Browning, J.V.; Miller, K.G.; McLaughlin, P.P., Jr.; Edwards, L.E.; Kulpecz, A.A.; Powars, D.S.; Wade, B.S.; Feigenson, M.D.; Wright, J.D.

2009-01-01

282

Sedimentology of resedimented carbonates: Facies and geometrical characterisation of an upper Cretaceous calciturbidite system in Albania  

NASA Astrophysics Data System (ADS)

Carbonate turbidite systems are not as well studied as their siliciclastic counterparts, resulting in a lack of knowledge on their vertical and lateral organisation. Thus, a preliminary detailed sedimentological study was undertaken in the upper Cretaceous limestones of Albania, which have been described as brecciated limestones and, more recently, as calciturbidites. The sedimentological study of three outcrops (Piluri, Vanister and Muzina) allows the definition of different lithologies grading from fine- to coarse-grained sequences representing the calciturbidites, intercalated with debris flow deposits and thick slumped levels. The thin-section examination of several facies defined in the field shows a dominance of mud-rich microfacies with variable granulometry, texture (mainly wackestone to packstone and floatstone), and the mixing of bioclastic and lithoclastic grains from both shallow-water (intertidal/infratidal) and deep-water settings (slope/basin). The microfacies description and fauna determination support the gravity origin of these calciclastic limestones. According to previous studies of the Ionian Basin and the surrounding platforms, the upper Cretaceous calciturbidite system could be reasonably linked to regional tectonic instabilities in relation to the beginning of the convergence between the Africa and Eurasian plates. The lateral and vertical organisation of these carbonate gravity deposits favours a depositional model over the apron model and that these deposits were fed by material derived from either the Apulian or the Kruja platform, through faulted shelf breaks.

Rubert, Yolaine; Jati, Mohamed; Loisy, Corinne; Cerepi, Adrian; Foto, Gjergji; Muska, Kristaq

2012-06-01

283

EARTHSCIENCESwww.earthsciences.osu.edu S C H O O L O F  

E-print Network

Earth Sci 4502 Stratigraphy and Sedimentology 4 Earth Sci 1121 & 1122 b) Complete at least one of the following courses: Earth Sci 501 Paleontology 5 Earth Sci 502 Stratigraphy and Sedimentology 5 Earth Sci 550

Kubatko, Laura S.

284

INSIDE: SEDIMENTATION ACROSS THE TIDAL-FLUVIAL TRANSITION IN THE LOWER FRASER RIVER,  

E-print Network

documents this evidence based on paleontology, sedimentology, sequence stratigraphy, mineralogy, isotope Sedimentology and Stratigraphy, held in El Paso, Texas in April of 2010. The papers presented in this volume

Venditti, Jeremy G.

285

College of Earth, Ocean, and Atmospheric Sciences Oregon State University  

E-print Network

of Earth history, Stratigraphy and Sedimentology, geology field methods, and graduate courses in their area through significant contributions to the fields of Stratigraphy, Sedimentology, #12;and/or Earth Systems

286

The Paleogene pre-rift to syn-rift succession in the Dhofar margin (northeastern Gulf of Aden): Stratigraphy and depositional environments  

NASA Astrophysics Data System (ADS)

The Paleogene deposits on the northern passive margin of the Gulf of Aden record the transition from the pre-rift to the syn-rift stages of the southern Arabian plate margin. In southern Oman (Dhofar Region), the relative continuity of the sedimentary record offers the possibility to investigate the early deformation phases of the Aden rift system. A new detailed sedimentological and biostratigraphic analysis of the Cuisian to Rupelian deposits of the Dhofar region allows to define a second-order transgressive-regressive cycle, that can be further subdivided into four third-order sequences between the Late Cuisian and the Early Rupelian time. The sequence stratigraphy established in this study has major implications for the understanding of the time equivalent deposits described in the eastern Arabian plate and illustrates the polyphased history of the initiation of the Aden Gulf rift system. The first two depositional sequences are controlled by a phase of deformation that only affects the eastern Oman margin, in relation with the tectonic activity at the Arabian-Indian plate boundary, during the Late Cuisian-Middle Lutetian. The last two depositional sequences record a westward migration of the deformation within the eastern realm of the proto-Gulf of Aden from the Bartonian. Priabonian uplift resulted in the basinward shift of the depositional system followed by a phase of tectonic subsidence that is recorded by the aggradation of lacustrine deposits in localized fault bounded basins. A subsequent major regional relative sea level fall related to domal uplift is recorded by terrigenous deposits (lower part of the Ashawq Formation) prior to the main phase of syn-rift tectonic subsidence (upper part of the Ashawq and Mughsayl formations) in Rupelian-Chattian times.

Robinet, J.; Razin, P.; Serra-Kiel, J.; Gallardo-Garcia, A.; Leroy, S.; Roger, J.; Grelaud, C.

2013-11-01

287

Late Quaternary Provenance and Flow Regime Reconstruction through Sedimentologic and Geochemical Evidence from the Bering/Chukchi Seas  

NASA Astrophysics Data System (ADS)

The last 20 kyr have been marked by great changes in the Arctic, as the Laurentide Ice Sheet melted and led to the submergence of the Bering Land Bridge and the re-opening of the Bering Strait (BS). The BS is a narrow connection (about 85 km wide) between the Arctic and Pacific Oceans averaging less than 50 m in depth, with present-day flow of seawater northward through the BS, from the Pacific to the Arctic. This flow is of vital importance to global ocean circulation through its role in formation and stability of North Atlantic Deep Water (NADW). An open BS is believed to speed dispersal of North Atlantic freshwater anomalies, both by keeping thermohaline circulation strong, and through reversals of flow through the BS when the North Atlantic is hosed with freshwater. When the BS is closed, these anomalies cannot efficiently dissipate and thermohaline circulation is weakened, which is considered a factor in climate perturbations outside of orbital forcing. Given the period of flux and transition in the Arctic following the Last Glacial Maximum (LGM), the paleoceanographic history of the Bering and Chukchi Seas post-LGM, is important to an understanding of Arctic Ocean circulation, and consequent climate impacts. Today the Arctic is in a period of rapid change, multi-year sea ice is disappearing, and the continuation of climatic stability of the Holocene appears to be at an end. Comprehension of the functioning of the Arctic as a dynamic system is essential to predict future response of the system to change, such as seawater salinity-density changes, lowered sea and land albedo, and rising temperatures. Changes in BS throughflow intensity and direction during deglaciation and submergence of the Bering Land Bridge are proposed and supported in modeling simulations, and are thought to occur during millennial-scale climate changes. We have conducted a coupled sedimentological and geochemical investigation of a suite of marine sediment cores from the Bering and Chukchi Seas. Elemental, isotopic, and grain size shifts correspond to changes in sediment routing, identifying changes in the magnitude and direction of throughflow in the BS. Major and trace element geochemistry spanning the past ~30 kyr was derived using an ITRAX XRF core scanner. Age control is well established by previous studies for a majority of the cores, primarily radiocarbon dates on diatoms. Elemental XRF data indicate significant change during the Bølling-Allerød warming around 15 kyr, and the opening of the BS at 11 kyr. During both of these periods there is a drop in Ti, Fe, K, and Ba with a corresponding rise in Cl, Ca, and Br. These data, in concert with the other sedimentologic data, infer shifts in paleo-flow conditions and sediment provenance during this time period. A key goal is the identification of how variations in geochemical properties correspond to bulk biogeochemical or biomarker variability, in comparison to sea ice proxies. The data being collected will add to a growing understanding of the Arctic as a dynamic system and answer questions concerning the post-glacial and Holocene evolution of changes that took place across the marine portion of the Bering Land Bridge.

Pelto, B. M.; Brigham-Grette, J.; Kocis, J. J.; Petsch, S.

2013-12-01

288

From Grains to Basin: An Example of a Project-Based Sedimentology Exercise  

NSDL National Science Digital Library

To prepare for this project, students have gained familiarity with thin-section preparation and the use of analytical equipment such as the XRD. The students have also learnt how to measure and interpret paleocurrent data. They have read background articles on the basin of study. In the field, students learn how to measure a stratigraphic section and the application of Walther's Law. The goal is to combine the skills acquired earlier in the class to interpret the stratigraphy, facies, depositional history and paleogeography of an outcrop in the field. This exercise also links sedimentation and tectonics.

Harmsen, Frederika

289

Sedimentology and geochemistry of an exceptionally preserved last interglacial sapropel S5 in the Levantine Basin (Mediterranean Sea)  

E-print Network

in the Levantine Basin (Mediterranean Sea) Tobias Moller a, , Hartmut Schulz a , Yvonne Hamann b , Olaf Dellwig c Lange Keywords: sapropel Mediterranean geochemistry sedimentology Eemian interglacial A combined study region of the eastern Mediterranean. The thickness of the studied sapropel S5 varies be- tween 85 and 91

Gilli, Adrian

290

Sedimentology, geochemistry and palaeogeographic implications of volcanic rocks in the Upper Archaean Campbell Group, western Kaapvaal craton, South Africa  

Microsoft Academic Search

Tuffs and lava interbedded in Campbell Group carbonates and shales are investigated for their sedimentological and geochemical properties. The most proximal tuffs occur at the southwestern margin of the Kaapvaal craton, in Griqualand West. They were deposited in a shallow-marine to tidal carbonate environment from hydroclastic eruptions. The tuffs along this margin are subdivided into two main facies types: (1)

Wladyslaw Altermann

1996-01-01

291

Sedimentology, dating and palaeoclimatic interpretation of A 76.3 ka record from Lago Grande di Monticchio, southern Italy  

Microsoft Academic Search

Detailed sedimentological and microstratigraphical investigations of lacustrine sediments from Lago Grande di Monticchio (southern Italy) provide a time scale based on rates of sedimentation obtained from annual laminations. Although not annually laminated throughout, a time scale covering the last 76.3 ka is available by interpolation of sedimentation rates. Results of this chronology agree with radiocarbon dates, and with ArAr dates

Bernd Zolitschka; Jörg F. W. Negendank

1996-01-01

292

Late-Quaternary morpho-sedimentology and submarine mass movements of the Betsiamites area, Lower St. Lawrence Estuary, Quebec, Canada  

E-print Network

Late-Quaternary morpho-sedimentology and submarine mass movements of the Betsiamites area, Lower St 2008 Accepted 4 March 2008 Available online xxxx Keywords: submarine mass movements morpho submarine geomorphology was revealed from multibeam bathymetry and seismic reflection surveys conducted

Long, Bernard

293

Stratigraphy, geochronology and evolution of the Mt. Melbourne volcanic field (North Victoria Land, Antarctica)  

NASA Astrophysics Data System (ADS)

Mt. Melbourne (2,732 m a.s.l.) is a large quiescent stratovolcano located in Northern Victoria Land (Antarctica) and is one of a handful of volcanoes on the Antarctic plate with the potential for large-scale explosive eruptions. During the XVIII Italian Expedition in 2002-2003, the Mt. Melbourne volcanic succession was studied in terms of stratigraphy and sampled for 40Ar/39Ar age determinations and geochemistry. The early, Lower Pleistocene, volcanism was largely alkali basaltic to hawaiitic in composition and monogenetic in style, producing tens of small scoria cones and lava flows scattered over a wide area across the Transantarctic Mountains (Random Hills Period). During the Middle Pleistocene, volcanic activity focused to the area of the Mt. Melbourne stratovolcano, where several monogenetic centres show the transition from early sub-glacial/subaqueous conditions to emergent subaerial conditions (Shield Nunatak Period). The oldest exposed deposit associated with the early activity of the Mt. Melbourne stratovolcano (Mt. Melbourne Period) is a trachytic subaerial ignimbrite dated at 123.6 ± 6.0 ka, which reflects the establishment of a crustal magma chamber. Above the ignimbrite a succession of alkali basaltic, hawaiitic, and subordinate benmoreitic lavas and scoria cones is exposed, dated at 90.7 ± 19.0 ka. The Holocene deposits are exposed at the top of Mt. Melbourne, where the crater rim is composed of trachytic to rhyolitic pumice fall deposits, which are also extensively dispersed around the volcano, likely originated from Plinian-scale eruptions. The most recent explosive deposit proved difficult to date accurately because very low quantities of radiogenic 40Ar were released, resulting in imprecise plateau ages of 50 ± 70 and 35 ± 22 ka.

Giordano, Guido; Lucci, Federico; Phillips, David; Cozzupoli, Domenico; Runci, Valentina

2012-11-01

294

Molecular and isotopic stratigraphy in an ombrotrophic mire for paleoclimate reconstruction  

NASA Astrophysics Data System (ADS)

A 40 cm deep Sphagnum-dominated peat monolith from Bolton Fell Moss in Northern England was systematically investigated by lipid molecular stratigraphy and compound-specific ? 13C and ?D analysis using gas chromatography (GC), GC-mass spectrometry (GC-MS), GC-combustion-isotope ratio-MS (GC-C-IRMS) and GC-thermal conversion-IRMS (GC-TC-IRMS) techniques. 210Pb dating showed the monolith accumulated during the last ca. 220 yr, a period encompassing the second part of Little Ice Age. While the distributions of lipids, including n-alkan-1-ols, n-alkan-2-ones, wax esters, sterols, n-alkanoic acids, ?,?-alkandioic acids and ?-hydroxy acids, display relatively minor changes with depth, the cooler climate event was recorded in the concentrations of n-alkanes and organic carbon, CPI values of n-alkanes and n-alkanoic acids, and the ratio of 5- n-alkylresorcinols/sterols. Superimposed on the fossil fuel effect, the relatively cooler climate event was also recorded by ? 13C values of individual hydrocarbons, especially the C 23n-alkane, a major compound in certain Sphagnum spp. The ?D values of the C 29 and C 33n-alkanes correlated mainly with plant composition and were relatively insensitive to climatic change. In contrast the C 23n-alkane displayed variation that correlated strongly with recorded temperature for the period represented by the monolith, agreeing with previously reported deuterium records in tree ring cellulose spanning the same period in Scotland, Germany and the USA, with more negative values occurring during the second part of Little Ice Age. These biomarker characteristics, including the compound-specific ? 13C and ?D records, provide a new set of proxies of climatic change, potentially independent of preserved macrofossils which will be of value in deeper sections of the bog where the documentary records of climate are unavailable and humification is well advanced.

Xie, Shucheng; Nott, Chris J.; Avsejs, Luke A.; Maddy, Darrel; Chambers, Frank M.; Evershed, Richard P.

2004-07-01

295

Mediterranean tephra stratigraphy revisited: Results from a long terrestrial sequence on Lesvos Island, Greece  

NASA Astrophysics Data System (ADS)

A composite 40.2 m sediment sequence from Megali Limni, Lesvos Island, Greece, spanning the interval from 22 to 62 ka BP, contains six Pleistocene tephra layers, which can be identified on the basis of their major and trace elemental compositions. The youngest tephra deposit correlates with the 22 ka Y-2 marker, erupted during the Cape Riva eruption of Santorini. The second tephra originates from the Campanian area in Italy and corresponds to the Campanian Ignimbrite eruption (the 39 ka Y-5 marker). The next two layers are compositionally identical, and originate from Eastern islands of the Hellenic Arc; they could potentially correspond to the Upper and Lower Pumice eruptions of Nisyros or some other previously unidentified eruption from Yali. The fifth stratum corresponds to the Y-6 marker, which erupted during the Green Tuff eruption of the Pantelleria Island. The source of the last tephra layer is either the Yali-Nisyros complex or Central Anatolia; no specific corresponding eruption has yet been found. Long distal tephra sequences within terrestrial settings are rare in the eastern Mediterranean and the Megali Limni record contains the most complete sequence to date. Moreover, its age model, based on independent chronologies such as AMS and conventional radiocarbon dates and high-resolution pollen stratigraphy, provides new ages for these eruptions and places them within the context of the millennial-scale palaeoenvironmental variability of the last glacial period. Finally, the recognition of the Pantelleria tephra in this locality considerably extends the confirmed Northerly and Easterly distribution of this widespread and distinctive unit, while the existence of the Nisyros-Yali tephras on Lesvos refutes the current belief of limited tephra dispersal and small magnitude of these eruptions.

Margari, V.; Pyle, D. M.; Bryant, C.; Gibbard, P. L.

2007-06-01

296

Stratigraphy and paleogeography of the Cretaceous in Arabian Peninsula  

SciTech Connect

The Cretaceous of the Arabian Peninsula is divided into three major units by regional unconformities: Lower Cretaceous Thamama Group (Berriasian-middle Aptian), middle Cretaceous Wasia Group (Albian-Turonian), and Upper Cretaceous Aruma Group (Coniacian-Maestrichtian). The profusion of named stratigraphic units in the area reflects not only the lithologic variation resulting from facies changes, but also terminologies adopted by different companies. The authors provide a stratigraphic nomenclature defining standard type sections and indicate synonymies, which follow the recommendation of 10th Geological Liaison Meeting and hence are acceptable to operators in the area. The sedimentologic history of the area was presented in a series of paleogeographic maps, which they relate to the regional tectonic framework. The maps show a predominantly carbonate shelf ramp bordering a land area to the north and west. The principal change in depositional environment occurs during the Upper Cretaceous, as a result of tectonic activity. Less significant changes are attributed to eustatic sea level fluctuations, on which tilting caused by tectonic movement may be superposed during the Lower and middle Cretaceous. The major producing horizons lie below the regional unconformities; secondary porosity in the shelf reefal buildups was developed during subaerial exposure in the Shuaiba Formation (early-middle Aptian), in the Mishrif Formation (late Cenomanian), and in the Simsima Formation (Maestrichtian).

Alsharhan, A.S.; Nairn, A.E.M.

1986-05-01

297

Carbonate fracture stratigraphy: An integrated outcrop and 2D discrete element modelling study  

NASA Astrophysics Data System (ADS)

Constraining fracture stratigraphy is important as natural fractures control primary fluid flow in low matrix permeability naturally fractured carbonate hydrocarbon reservoirs. Away from the influence of folds and faults, stratigraphic controls are known to be the major control on fracture networks. The fracture stratigraphy of carbonate nodular-chert rhythmite successions are investigated using a Discrete Element Modelling (DEM) technique and validated against observations from outcrops. Comparisons are made to the naturally fractured carbonates of the Eocene Thebes Formation exposed in the west central Sinai of Egypt, which form reservoir rocks in the nearby East Ras Budran Field. DEM allows mechanical stratigraphy to be defined as the starting conditions from which forward numerical modelling can generate fracture stratigraphy. DEM can incorporate both stratigraphic and lateral heterogeneity, and enable mechanical and fracture stratigraphy to be characterised separately. Stratally bound stratified chert nodules below bedding surfaces generate closely spaced lateral heterogeneity in physical properties at stratigraphic mechanical interfaces. This generates extra complexity in natural fracture networks in addition to that caused by bed thickness and lithological physical properties. A series of representative geologically appropriate synthetic mechanical stratigraphic models were tested. Fracture networks generated in 15 DEM experiments designed to isolate and constrain the effects of nodular chert rhythmites on carbonate fracture stratigraphy are presented. The discrete element media used to model the elastic strengths of rocks contain 72,866 individual elements. Mechanical stratigraphies and the fracture networks generated are placed in a sequence stratigraphic framework. Nodular chert rhythmite successions are shown to be a distinct type of naturally fractured carbonate reservoir. Qualitative stratigraphic rules for predicting the distribution, lengths, spacing, tortuosity, apertures and quantitative fracture indices (P21, P22 and fractal dimension) of natural fractures in the subsurface are generated from DEM fracture networks. The results of this study have widespread significance for characterising naturally fractured carbonate nodular-chert rhythmite reservoirs.

Spence, Guy; Finch, Emma

2013-04-01

298

Preliminary Sequence stratigraphy framework of the SW part of the Actopan Platform, Lower Cretaceous, Hidalgo, Mexico  

NASA Astrophysics Data System (ADS)

The oldest sedimentary rocks in what is known as the Actopan Platform, in the State of Hidalgo, Mexico, are superbly exposed toward the southwestern part of such platform. A detailed stratigraphic/sedimentologic study was carried out to a 623 m-thick section; this study was focused to establish a sequence stratigraphic framework. The base of the section consists of a Lower Cretaceous 6223-m thick, mixed siliciclastic-carbonate sedimentary succession that has been named Santuario Formation. The terrigenous facies of this unit correspond to red beds that consist of shales, sandstones y few conglomerates deposited under continental conditions (fluvial). White and yellowish sandstones, possibly deposited by deltaic systems, occur in minor amounts. A tuff layer is found in its lower part. The carbonate facies of the Santuario Formation consist mainly of skeletal mudstones/wackestones de bioclastos-peloides and subordinate quantities of sandy dolostones, skeletal packstones/grainstones and rudist (requeniids) boundstones. The middle and upper parts of the studied stratigraphic section correspond to an essentially carbonate succession that in known as El Abra Formation. This unit is comprised of the following facies: skeletal mudstones/wackestones, skeletal packstones/grainstone, and minor rudist (requeniid and Chondrodonta) boundstones and cryptalgal laminites deposited in shallow subtidal lagoon to tidal flat conditions. At this location, a "Middle" Cretaceous age (Albian-Cenomanian) has been assigned to the El Abra Formation. However, the common presence of the benthic foraminifer Chofatella decipiens Schlumberger in these facies indicates that their age extends, at least, to the Lower Cretaceous (Barremian). This age was confirmed with the dating of zircons in tuff deposited in the base section. The carbonate facies of the Santuario Formation stack forming fifth-order subtidal cycles or parasequences. While the carbonate facies of the El Abra Formation also stack forming subtidal and peritidal cycles. In turn, the fifth order cycles also stack forming fourth-order high frequency sequences. These sequences in the Santuario Formation are distinguished by the presence in their bases of the red beds interpreted as their lowstand systems tracts.

Abascal, G.; Murillo-Muñeton, G.

2013-05-01

299

Correlation of Lithology to Sequence Stratigraphy: Canterbury Basin, New Zealand  

NASA Astrophysics Data System (ADS)

A major objective of IODP Expedition 317 to the Canterbury Basin, New Zealand was to date and sample clinoformal seismic sequences, sequence boundaries, and their associated facies to understand the role of eustasy in shaping sedimentation on this continental margin. Canterbury Basin stratigraphy has also been influenced by tectonics and along strike currents that must also be taken into consideration when evaluating the evolution of the margin. Sesimic stratigraphic analysis provided the large-scale framework for understanding margin architecture and for drilling Sites U1351 through U1354 across the shelf and upper slope. Nineteen regional seismic sequence bounding surfaces (U1-U19) were identified from the middle Miocene to Holocene in the sediments offshore of Canterbury Basin, New Zealand. Correlation of the lithology to seismic stratigraphy permits the identification of sedimentary packages with boundaries near the predicted depths of sequence boundaries U1-U19. These sedimentary packages have sharp basal contacts that separate coarse-grained sediment above from fine grained beneath. The coarse-grained sediment above the contacts is composed of greenish gray, fine to medium muddy sand or sandy mud containing abundant shells. Each sedimentary package can be as thick as 6 m. In contrast, the sediment beneath is composed of fine-grained mud that is heavily bioturbated. Remarkable correlation was found between the depths at which some basal contacts occur and the depths predicted for sequence boundaries U11-U19 (early Pliocene to Holocene) across the shelf and upper slope. Heterolithic lithologies characterize the depositional environments within mid- and late Pleistocene seismic sequences. In contrast, alternations of gray and green mud are common in the early Pleistocene and Pliocene. Marlstones with wavy laminations, ripples and sand lenses suggestive of current activity are typical of Miocene lithologies beneath the slope while chalks and limestones dominate the Oligocene sequences. These lithologic changes are also manifested in the architecture of the margin that evolved from a ramp morphology to a progradational margin with steeper slopes and abrupt shelf breaks. Further studies of the facies within depositional sequences and the associated sedimentary packages will permit improved correlation between lithology and seismics and a better understanding of the relative contributions of eustasy, along-strike currents and tectonics to sedimentation. Sesimic stratigraphic analysis will also permit comparison with other margins where similar sea level studies are underway, such as New Jersey.

Ryan-Mishkin, K.; McHugh, C. M.; Fulthorpe, C.; Morgan, D.; Shipboard Scientific Party, E.

2010-12-01

300

The INTIMATE event stratigraphy and recommendations for its use  

NASA Astrophysics Data System (ADS)

The North Atlantic INTIMATE (INtegration of Ice-core, MArine and TErrestrial records) group has previously recommended an Event Stratigraphy approach for the synchronisation of records of the Last Termination using the Greenland ice core records as the regional stratotypes. A key element of these protocols has been the formal definition of numbered Greenland Stadials (GS) and Greenland Interstadials (GI) within the past glacial period as the Greenland expressions of the characteristic Dansgaard-Oeschger events that represent cold and warm phases of the North Atlantic region, respectively. Using a recent synchronization of the NGRIP, GRIP, and GISP2 ice cores that allows the parallel analysis of all three records on a common time scale, we here present an extension of the GS/GI stratigraphic template to the entire glacial period. In addition to the well-known sequence of Dansgaard-Oeschger events that were first defined and numbered in the ice core records more than two decades ago, a number of short-lived climatic oscillations have been identified in the three synchronized records. Some of these events have been observed in other studies, but we here propose a consistent scheme for discriminating and naming all the significant climatic events of the last glacial period that are represented in the Greenland ice cores. In addition to presenting the updated event stratigraphy, we make a series of recommendations on how to refer to these periods in a way that promotes unambiguous comparison and correlation between different proxy records, providing a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations. The work presented is a part of a manuscript under review for publication in Quaternary Science Reviews. Author team: S.O. Rasmussen, M. Bigler, S.P.E. Blockley, T. Blunier, S.L. Buchardt, H.B. Clausen, I. Cvijanovic, D. Dahl-Jensen, S.J. Johnsen, H. Fischer, V. Gkinis, M. Guillevic, W.Z. Hoek, J.J. Lowe, J. Pedro, T. Popp, I.K. Seierstad, J.P. Steffensen, A.M. Svensson, P. Vallelonga, B.M. Vinther, M.J.C. Walker, J.J. Wheatley, and M. Winstrup (deceased).

Rasmussen, Sune O.

2014-05-01

301

New Geoscience Curriculum Environmental Geoscience track Directed Electives: take one from each category  

E-print Network

GEOSCI 430 Sedimentology and Stratigraphy 3 GEOSCI 204 Geologic Evolution of the Earth 4 GEOSCI 627 Sedimentology and Stratigraphy 3 Geobiology GEOSCI 455 Structural Geology 4 GEOSCI 304 Geobiology 3 Geoscience as a Public Problem 3 Required: GEOSCI 411 Energy Resources 3 GEOSCI 431 Sedimentology and Stratigraphy Lab 1

Sheridan, Jennifer

302

Geological Sciences 330 Fall 2007 Sedimentary Geology  

E-print Network

. Principles of sedimentology and stratigraphy. 4th edition. Prentice Hall, Upper Saddle River, NJ. 662 pp: Principles of Stratigraphy and Sedimentology (1) Week 2 10 Sept Sedimentary Particles: Weathering (13, 15 & 16) 28 Nov Integrated Stratigraphy and Sedimentology Lab 10: Well-log Interpretation Week 14

303

Geoscience Curriculum Environmental Geoscience track Directed Electives: take one from each category  

E-print Network

Introduction to Geologic Structures (Fall) 4 GEOSCI 430 Sedimentology and Stratigraphy 3 GEOSCI 204 Geologic 3 GEOSCI 375 Principles of Geochemistry 3 GEOSCI 430 Sedimentology and Stratigraphy 3 Geobiology: GEOSCI 411 Energy Resources 3 GEOSCI 431 Sedimentology and Stratigraphy Lab 1 GEOSCI 455 Structural

Carlson, Anders

304

Xavier Janson Professional Summary  

E-print Network

. Carbonates sedimentology and sequence stratigraphy. B. Petrophysics of carbonate. C. Seismic signature). Reservoir Characterization Research Laboratory (RCRL). C. Researcher, Sedimentology Department, Elf Record, 2009 - 2012 Associate Editor, Sedimentology, International Association of Sedimentologists, 2008

Yang, Zong-Liang

305

DESCRIPTIONS/STRATEGIES What can I do with this major?  

E-print Network

Sedimentology StructuralGeology Geophysics EconomicGeology Geomorphology Paleontology Fossil Energy Geologists. Minerals MiningGeology Mineralogy Geochemistry EconomicGeology Paleontology Stratigraphy Sedimentology) LANDSCAPE EnvironmentalGeology Sedimentology Hydrology Geomagnetism Earth Surface Dynamics Coastal & Marine

New Hampshire, University of

306

DESCRIPTIONS/STRATEGIES What can I do with this degree?  

E-print Network

Sedimentology StructuralGeology Geophysics EconomicGeology Geomorphology Paleontology Fossil Energy Geologists. Minerals MiningGeology Mineralogy Geochemistry EconomicGeology Paleontology Stratigraphy Sedimentology) LANDSCAPE EnvironmentalGeology Sedimentology Hydrology Geomagnetism Earth Surface Dynamics Coastal & Marine

Kaminsky, Werner

307

Earth Science The Wiess School of Natural Sciences  

E-print Network

and paleoceanography, stratigraphy, carbonate and siliciclastic sedimentology, igneous petrology, geochemis- try Sedimentology ESCI 334 Geological and Geophysical Techniques ESCI 390 Field Geology ESCI 442 Exploration Mineralogy and Optics or ESCI 332 Sedimentology ESCI 331 Structural Geology ESCI 334 Geological

Richards-Kortum, Rebecca

308

Sedimentology 001 What is sedimentology?  

E-print Network

by ... Water : running water causes rocks to collide, breaking rocks into smaller pieces and polishing them tell which type of erosion caused a sediment? Fluvial / Water erosion causes sediments to be 'well is to rub it against your teeth, if it feels 'gritty' and is small enough you have a hard time seeing grains

Frank, Tracy D.

309

Sedimentological data indicate greater range of water depths for Costistricklandia lirata in the Southern Appalachians  

SciTech Connect

Two distinct horizons of the pentamerid brachiopod Costistricklandia lirata occur in the upper part of the Red Mountain Formation (Lower Silurian) in northern Alabama. Stratigraphic and sedimentologic characteristics of the rocks associated with the brachiopods suggest water depths of 15-150 m during times of low rates of terrigenous influx. Costistricklandid assemblages from the lower horizon are composed of extremely large individuals in association with a diverse population of large corals. They are interpreted to have lived in a protected environment. In an overlying horizon, costistricklandids occur in growth position at the base of a thick siliciclastic interval. These brachiopods lived in a storm-dominated environment and were buried in situ by the rapid influx of sediment associated with a passing storm.

Bolton, J.C. (Univ. of Tennessee, Knoxville (USA))

1990-08-01

310

The February 27, 2010 Chile Tsunami - Sedimentology of runup and backflow deposits at Isla Mocha  

NASA Astrophysics Data System (ADS)

On February 27, 2010, at 3:34 am local time, an earthquake with Mw 8.8 occurred off the town of Constitución in Central Chile and caused a major tsunami beween Valaparaiso (c. 33°S) and Tirua (c. 38°S). Maximum runup heights of up to 10 m were measured on coastal plains. The cliff coast at Tirua recorded a runup height between 30 m and 40 m. Considering past tsunami events, respective deposits may be the only observable evidence, even though their preservation potential is limited. To understand how tsunami deposits form and how they can be identified in the geological record, it is of paramount importance to undertake detailed studies in the wake of such events. Here we report initial field data of a sedimentological post-tsunami field survey undertaken in Central Chile between March 31 and April 18, 2010. At selected localities we measured detailed topographic profiles including runup heights and inundation distances, and recorded the thickness, distribution and sedimentological features of the respective tsunami deposits, as well as erosional features caused by the tsunami. We found the most instructive and complete sedimentological record of the February 27, 2010 tsunami at the northern tip of Isla Mocha, a small island off the Chilean coast at c. 28.15°S. Runup distances vary between 400 m and 600 m, the flow depth exceeded 3 m at ca. 100 m from the coast. Runup heights reached up to 21 m above sea level. In a rare sedimentological case, deposits of tsunami runup and backwash could be distinguished. The runup phase was mainly documented by fields of boulders extending c. 360 m inland. Boulders had maximum weights of 12 t. They were oriented with their long axis parallel to the coast and the wave front. Algal veneers and barnacles on the boulder faces give evidence of entrainment in intertidal water depths. The boulders are now embedded in mostly structureless coarse shelly sand. These sands were originally entrained during near shore supratidal erosion of coastal plain terraces by the tsunami and transported inland during runup. Flow structures indicate that the sands were then re-deposited during backwash. Downcurrent of terrace steps the tsunami backwash produced large erosional gullies. The backwash deposits occur either as widespread covers blanketing microtopography consisting of dark pre-tsunami soils, or as depositional fans which prograde seaward over soils free of a sediment cover. The coarse to very coarse shell debris is comprised of fragmented or entire mollusk and crab cascs. Some coarser deposits also contain significant amounts of Tertiary sandstone bedrock gravels in parts freshly eroded by the tsunami. The deposits are either massive or imbricated, the imbrication identifying them as a product of backflow currents. The deposit thickness is commonly c. 10 to 15 cm. Around large boulders backflow partitioning and associated erosion and deposition permitted the generation of 0.8 m deep scours and accumulation of up to 80 cm thick backflow sands. The depositional angles at the fan fronts vary between 27° and 36°. Backflow fan surfaces are characterized by channel and overbank regions and flow structures like current ripples. Clusters of bedrock pebbles and mollusk cascs are distributed irregularly over the fan surfaces.

Bahlburg, H.; Spiske, M.

2010-12-01

311

Sedimentology of the Sbaa oil reservoir in the Timimoun basin (S. Algeria)  

SciTech Connect

In 1980 oil was discovered in the Timimoun portion of the Sbaa depression in Southern Algeria. Until that time this basin had produced only dry gas. Since the 1980 oil discovery, several wells have been drilled. Data acquired from these wells were analyzed and are presented in this study. The oil reservoir is located within a sandstone interval of the Sbaa formation which has an average thickness of 75 m. The Sbaa lies between the Tournaisian (Lower Carboniferous) silts and the Strunian (uppermost Devonian) shales and sandstones. The sedimentological study reveals that the Sbaa formation contains bimodal facies consisting of coarse siltstones and fine sandstones. The sequence has been attributed to a deltaic environment developed in the central part of the Ahnet basin. The sources of the associated fluvial system are from the surrounding In-Semmen, Tinessourine, and Arak-Foum-Belrem paleohighs. Thermoluminescence indicates the provenance for the Sbaa sands was the crystalline basement Cambrian and Ordovician sections.

Mehadi, Z. (Institute des Hydrocarbures et de la Chimique, Boumerdes (Algeria))

1990-05-01

312

First ERTS-1 results in southeastern France: Geology, sedimentology, pollution at sea  

NASA Technical Reports Server (NTRS)

Results obtained by four ERTS projects in southeastern France are summarized. With regard to geology, ERTS photos of Western Alps are very useful for tectonic interpretation because large features are clearly visible on these photographs even though they are often hidden by small complicated structures if studied on large scale documents. The 18-day repetition coverage was not obtained, and time-varying sedimentological surveys were impossible. Nevertheless, it was possible to delineate the variations of the shorelines in the Rhone Delta for a period covering the least 8,000 years. Some instances of industries discharging pollutant products at sea were detected, as well as very large anomalies of unknown origin. Some examples of coherent optical processing have been made in order to bring out tectonic features in the Alps mountains.

Fontanel, A.; Guillemot, J.; Guy, M.

1973-01-01

313

Sedimentology models from activity concentration measurements: application to the "Bay of Cadiz" Natural Park (SW Spain).  

PubMed

A previous study on seabed sediments of the Bay of Cadiz (SW of Spain) enabled us to identify several relations between sedimentological variables and activity concentrations of environmental radionuclides such as (137)Cs, (226)Ra, (232)Th and (40)K. In this paper the study has been extended to a large neighbouring inter-tidal area in order to establish if the above mentioned models can be generalized. As a result we have determined that the measured activity concentrations are closely to the values predicted by the theoretical models (correlation coefficient range=0.85-0.93). Furthermore, the proposal model for granulometric facies as a function of activity concentrations of the abovementioned radionuclides provides for the sediments distribution a representation which agrees with the values of the tidal energy distribution obtained using numeric models calibrated with experimental data from current meters and water level recorders. PMID:19136180

Ligero, R A; Vidal, J; Meléndez, M J; Hamani, M; Casas-Ruiz, M

2009-03-01

314

Soil sedimentology at Gusev Crater from Columbia Memorial Station to Winter Haven  

USGS Publications Warehouse

A total of 3140 individual particles were examined in 31 soils along Spirit's traverse. Their size, shape, and texture were quantified and classified. They represent a unique record of 3 years of sedimentologic exploration from landing to sol 1085 covering the Plains Unit to Winter Haven where Spirit spent the Martian winter of 2006. Samples in the Plains Unit and Columbia Hills appear as reflecting contrasting textural domains. One is heterogeneous, with a continuum of angular-to-round particles of fine sand to pebble sizes that are generally dust covered and locally cemented in place. The second shows the effect of a dominant and ongoing dynamic aeolian process that redistributes a uniform population of medium-size sand. The texture of particles observed in the samples at Gusev Crater results from volcanic, aeolian, impact, and water-related processes. Copyright 2008 by the American Geophysical Union.

Cabrol, N.A.; Herkenhoff, K.E.; Greeley, R.; Grin, E.A.; Schroder, C.; d'Uston, C.; Weitz, C.; Yingst, R.A.; Cohen, B.A.; Moore, J.; Knudson, A.; Franklin, B.; Anderson, R.C.; Li, R.

2008-01-01

315

Morphological and sedimentological characters of the East Sea (Japan Sea) continental margin  

NASA Astrophysics Data System (ADS)

Consecutive geophysical and geological surveys were conducted in the southwestern margin of the East Sea (Japan Sea) in Korea in order to investigate the complex patterns of morphological and sedimentological characters as well as to understand their relationship with various oceanographic agents. A total of 4,200 line-km seismic records and 172 samples were analyzed so that a series of maps could be made and compared. Based on the results it is revealed that the study area could be divided into five unique subenvironments according to slope changes and surface sediments; flat monotonous shelf (inner and outer), steep and irregular slope (upper and lower) and gentle basin plain. Tectonic movement, sea level change, earthquake, and regional current system are seemingly the major controlling factors to formulate the regional scale morphology and sediment distribution pattern.

Kim, Seong-Pil; Koo, Bon Young; Kong, Gee Soo; Um, Inkwon; Lee, Gwang Soo; Chung, Gong Soo; Choi, Jin-Yong

2014-05-01

316

Sedimentological and geochemical characterization of the Cretaceous strata of Calabar Flank, southeastern Nigeria  

NASA Astrophysics Data System (ADS)

An integrated sedimentological and geochemical evaluation has been carried out on the Cretaceous sediments of the Calabar Flank. This study is to characterize the provenance, depositional environments and hydrocarbon potentials. The techniques involved field descriptions, textural parameters, petrographic analysis and biostratigraphic studies using standard sedimentological methods. The geochemical studies involved the determination of major oxides and trace elements using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS); Total Organic Carbon (TOC) and Rock Eval Pyrolysis. Results show that sandstone from Awi Formation have elongation ratio ranging from 0.4b to 0.9, oblate-prolate index and maximum sphericity index range from 9.6 to 9.7 and 0.5 to 0.9 respectively. The sandstone units are arkosic and mineralogically immature (MI = 3); ZTR indexes range from 54.6% to 82.5%, with tourmaline, zircon, staurolite, garnet, apatite, augite and rutile grains being angular-sub-angular. This suggests nearness to source, and that Awi Formation was deposited in a fluvial environment. The limestone deposit of Mfamosing Formation is predominantly bioclastic consisting of algal stromatolites, oolitic and pelloidal grainstones/packstones with high carbonate content. The dark grey fissile shales of Nkporo and Ekenkpon Formations indicate deposition in quiet oxic and/or anoxic conditions. Average TOC suggests good source rocks. Predominance of Type III kerogen, Tmax and hydrocarbon source potential of Mfamosing, Ekenkpon, New Netim Marl and Nkporo Formations suggest marginal mature to mature source rocks deposited in shallow continental to open marine setting that some gas may have been generated. The sediments are derived from passive continental margin in plutonic humid palaeoclimatic setting of continental block province.

Boboye, O. A.; Okon, E. E.

2014-11-01

317

An event stratigraphy for the Last Glacial–Holocene transition in eastern middle Sweden: results from investigations of varved clay and terrestrial sequences  

Microsoft Academic Search

This paper presents an event stratigraphy for the Last Glacial–Holocene transition in eastern middle Sweden. The event stratigraphy for eastern middle Sweden comprises ten events and covers the time-span from ca 12,900 to 10,200calyrBP. The local event stratigraphy has been linked to the GRIP isotopic event stratigraphy by different correlations. The onset of the Younger Dryas is dated to 12,650calyrBP.

Jonas Björck; Thomas Andrén; Stefan Wastegård; Göran Possnert; Kristian Schoning

2002-01-01

318

The magnetic polarity stratigraphy of the Mauch Chunk Formation, Pennsylvania  

PubMed Central

Three sections of Chesterian Mauch Chunk Formation in Pennsylvania have been studied paleomagnetically to determine a Late Mississippian magnetic polarity stratigraphy. The upper section at Lavelle includes a conglomerate with abundant red siltstone rip-up clasts that yielded a positive conglomerate test. All samples were subjected to progressive thermal demagnetization to temperatures as high as 700°C. Two components of magnetization were isolated: a synfolding “B” component and the prefolding “C” component. The conglomerate test is positive, indicating that the C component was acquired very early in the history of the sediment. A coherent pattern of magnetic polarity reversals was identified. Five magnetozones were identified in the upper Lavelle section, which yields a pattern that is an excellent match with the pattern of reversals obtained from the upper Mauch Chunk at the original type section of the Mississippian/Pennsylvanian boundary at Pottsville, PA. The frequency of reversals in the upper Mississippian, as identified in the Mauch Chunk Formation, is approximately one to two per million years, which is an average for field reversal through time. PMID:15353597

Opdyke, Neil D.; DiVenere, Victor J.

2004-01-01

319

Stratigraphy of the Jurassic system in northern Egypt  

SciTech Connect

A regional synthesis is presented of the stratigraphy of Jurassic strata in Egypt north of 30/degree/N, based on the study of about 80 wells and outcrops from northeastern Egypt. Almost all fossil groups have been investigated for biostratigraphic control. Published work on ammonite faunas from Gebel el Maghara (north Sinai) is integrated with extensive original work on palynofloras (and, to a lesser extent, ostracod/foraminiferal faunas) recovered from marine rocks in the subsurface. The recovery of rich dinocyst assemblages enables the recognition of a ten-fold zonation scheme, largely within the Middle-Late Jurassic sedimentary package. The upper limit of this package is marked by the Cimmerian erosional event; strata younger than Oxfordian are rarely preserved. Only east of 30/degree/E is significant sedimentation known to have occurred immediately prior to the major early Bajocian transgressive event. Thereafter mean sea level rose steadily. The Lower Triassic-Lower Jurassic sedimentary package is poorly understood, largely the result of scanty and ambiguous stratigraphic evidence. However, regional correlations suggest that only very thin earliest Jurassic (Hettangian ) clastic deposition succeeded a sequence of Upper Triassic carbonates and evaporites (Wadi en Natrun Formation) in the north. Arising from these studies is a standard lithostratigraphical scheme. The upper sedimentary package, the Gebel el Maghara Group, comprises three formations (Masajid, Khatatba, and Inmar) and seven members; new units are defined and old units redefined.

Keeley, M.L.; Shaw, D.; Forbes, G.A.

1988-08-01

320

Acoustic stratigraphy of Bear Lake, Utah-Idaho: late Quaternary sedimentation patterns in a simple half-graben  

USGS Publications Warehouse

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.

Colman, Steven M.

2006-01-01

321

Lithofacies, depositional environments, and regional stratigraphy of the lower Eocene Ghazij Formation, Balochistan, Pakistan  

USGS Publications Warehouse

A regional stratigraphic investigation of one of the most important coal-bearing lithostratigraphic units in Pakistan, the report includes sedimentologic observations taken from outcrops and measured sections, information derived from petrographic and paleontologic analyses, depositional interpretations, and descriptions of regional trends.

Johnson, Edward A.; Warwick, P.D.; Roberts, S.B.; Khan, I.H.

1999-01-01

322

Carbonate platform evolution and conodont stratigraphy during the middle Silurian Mulde Event, Gotland, Sweden  

Microsoft Academic Search

E vidence from sedimentology and conodont biostratigraphy is used to reinterpret the mid-Homerian (Late Wenlock) succession on Gotland, Sweden. A new conodont zonation includes from below: the Ozarkodina bohemica longa Zone (including five subzones), the Kockelella ortus absidata Zone and the Ctenognathodus murchisoni Zone (two taxa are named, Ozarkodina bohemica longa and Pseudooneotodus linguicornis). These new zones are integrated with

MIKAEL C ALNER; L ENNART J EPPSSON

2003-01-01

323

Strontium and carbon isotope stratigraphy of the Late Jurassic shallow marine limestone in western Palaeo-Pacific, northwest Borneo  

E-print Network

Strontium and carbon isotope stratigraphy of the Late Jurassic shallow marine limestone in western-Pacific a b s t r a c t Strontium and carbon isotope stratigraphy was applied to a 202 m-thick shallow marine, which was deposited in the western Palaeo-Pacific. Strontium isotopic ratios of rudist specimens suggest

Gilli, Adrian

324

Upper Cretaceous subsurface stratigraphy and structure of coastal Georgia and South Carolina  

USGS Publications Warehouse

Upper Cretaceous subsurface stratigraphy and structure of coastal Georgia and South Carolina is based on the study of 24 wells along two transects, one extending across the seaward-dipping sedimentary basin termed the 'Southeast Georgia Embayment' northeastward to the crest of the Cape Fear Arch, and the other alined east-west, parallel to the basin axis and including the COST GE-l well on the Outer Continental Shelf. A new biostratigraphic analysis, using calcareous nannofossils, of the Fripp Island, S.C., well and reinterpretations of the Clubhouse Crossroads corehole 1, South Carolina, and other wells in South Carolina, Georgia, and northernmost Florida have made possible the comparison and reevaluation of stratigraphic interpretations of the region made by G. S. Gohn and others in 1978 and 1980 and by P. M. Brown and others in 1979. The present study indicates that within the Upper Cretaceous section the stratigraphic units formerly assigned a Cenomanian (Eaglefordian and Woodbinian) age are Coniacian (Austinian) and Turonian (Eaglefordian) in age. A previously described hiatus encompassing Coniacian and Turonian time is not present. More likely, a hiatus is probably present in the upper Turonian, and major gaps in the record are present within the Cenomanian and between the Upper Cretaceous and the pre-Cretaceous basement. After an erosional episode in Cenomanian time that affected the section beneath eastern Georgia and South Carolina, Upper Cretaceous marine clastic and carbonate rocks were deposited on a regionally subsiding margin that extended to the present Blake Escarpment. In contrast, during Cenozoic time, especially in the Eocene, subsidence and sedimentation rates were uneven across the margin. A thick progradational sequence of carbonate rocks accumulated in the Southeast Georgia Embayment and also built the present Continental Shelf, whereas farther offshore a much thinner layer of sediments was deposited on the Blake Plateau. There is no general agreement on the exact placement of the Cenomanian-Turonian boundary in Europe or the United States Western Interior, and the widespread Sciponoceras gracile ammonite zone represents an interval of equivocal age between accepted Cenomanian and Turonian strata. The extinction of the foraminifer genus Rotalipora took place within the Sciporwceras gracile zone; it is used here to identify the Cenomanian-Turonian boundary. Pollen zone IV (Complexiopollis-Atlantopollis assemblage zone) is an important and widespread biostratigraphic unit characterized by a distinctive spore and pollen flora. It is consistently associated with lower Turonian calcareous nannofossils on the Atlantic continental margin; these nannofossil assemblages are also present in pollen zone IV, in strata that encompass the Sciponoceras gracile zone and the lower part of the Mytiloides labiatus zone in the Gulf Coastal Plain at Dallas, Tex.

Valentine, Page C.

1982-01-01

325

Depositional sequence analysis and sedimentologic modeling for improved prediction of Pennsylvanian reservoirs (Annex 1)  

SciTech Connect

Interdisciplinary studies of the Upper Pennsylvanian Lansing and Kansas City groups have been undertaken in order to improve the geologic characterization of petroleum reservoirs and to develop a quantitative understanding of the processes responsible for formation of associated depositional sequences. To this end, concepts and methods of sequence stratigraphy are being used to define and interpret the three-dimensional depositional framework of the Kansas City Group. The investigation includes characterization of reservoir rocks in oil fields in western Kansas, description of analog equivalents in near-surface and surface sites in southeastern Kansas, and construction of regional structural and stratigraphic framework to link the site specific studies. Geologic inverse and simulation models are being developed to integrate quantitative estimates of controls on sedimentation to produce reconstructions of reservoir-bearing strata in an attempt to enhance our ability to predict reservoir characteristics.

Watney, W.L.

1992-01-01

326

A laminated carbonate record of mid-continental climate during the late Glacial and Holocene from Martin Lake, northeastern Indiana: Initial sedimentological and chronological results  

NASA Astrophysics Data System (ADS)

Paleoclimate records from the mid-continental United States that span the late Glacial and Holocene with sub-decadal resolution are rare. This is especially true for geochemical records that capture the isotopic composition of precipitation or local precipitation/evaporation balances. As a result, many questions remain about the hydrologic expression of abrupt climate events in this region that today is one of the largest agricultural centers in the world. Here, we present preliminary limnological, sedimentological and chronologic data from a set of new sediment cores from Martin Lake in northeastern Indiana. Today, this kettle lake is hydrologically open with persistent water column stratification and bottom water anoxia. Imaging of the ~8 m composite sediment archive shows that mm-scale couplets composed of alternating layers of organic matter and carbonate minerals are present throughout the core. Ongoing radiometric dating of the cores will be used to determine the depositional significance of the couplets and their potential for additional chronologic constraint. Initial basal age estimates, however, suggest that the composite record may extend back as far as 19,000 cal yr B.P. The Martin Lake record therefore holds great potential for providing a carbonate d18O record of late Glacial and Holocene climate events at sub-decadal resolution.

Stamps, L. G.; Bird, B. W.; Gilhooly, W.

2013-12-01

327

Little ice age as recorded in the stratigraphy of the tropical quelccaya ice cap  

Microsoft Academic Search

The analyses of two ice cores from a southern tropical ice cap provide a record of climatic conditions over 1000 years for a region where other proxy records are nearly absent. Annual variations in visible dust layers, oxygen isotopes, microparticle concentrations, conductivity, and identification of the historical (A.D. 1600) Huaynaputina ash permit accurate dating and time-scale verification. The fact that

L. G. Thompson; E. Mosley-Thompson; P. M. Grootes

1986-01-01

328

High-resolution palaeoecological and sedimentological records as a tool for understanding pre- and protohistoric settlement and land-use systems in Sandy Flanders (NW Belgium)  

NASA Astrophysics Data System (ADS)

The area of Sandy Flanders, situated between the North Sea coast and the lower course of the Scheldt River in NW Belgium, is a relatively flat and low-lying area situated at the southern limit of the lowland cover sand region of the NW European plain. During the Late Pleniglacial and the Late Glacial, numerous, generally small but elongated sand dunes, shallow lakes and wet depressions were formed. During the last three decades intense archaeological prospection has taken place in this region, which is now one of the most intensively surveyed areas of NW Europe. This has led to the production of archaeological distribution maps, which show a distinct pattern regarding the temporal and spatial distribution of these archaeological sites. Some areas with a presumed high ecological value, such as the large but shallow Late Glacial fossil lake of the Moevaart Depressie (ca. 15km long and 2,5km wide), seem to have been attractive settlement locations in Prehistory, given the high amount of close-lying sites along its borders and on the cover sand ridge on its northern border. Habitation however seems to have ‘moved' in time, and is completely absent in Protohistory and even the Roman Period. During the Late Glacial and Holocene the landscape in the Belgian area of Sandy Flanders was subjected to major changes due to climatic fluctuations, and besides human factors, environmental conditions such as topography, soil, vegetation, but also hydrology and climate, may have influenced settlement conditions throughout time and played a role in this change in site location and the occupational history of the region. In this light an inter-disciplinary project 'Prehistoric settlement and land-use systems in Sandy Flanders (NW Belgium): a diachronic and geoarchaeological approach' (GOA project, UGent), involving archaeology, geography, palaeoecology, sedimentology and geophysical survey, has been undertaken. The study of both "empty" and densely inhabited areas is ongoing and aims at analyzing the settlement dynamics of the area of Sandy Flanders in terms of environmental potentials (theory of "wandering farmsteads") and the human impact ("enculturation") on the landscape. Likewise, we seek to investigate the reasons why other areas, which were inhabited in previous periods (e.g. the Moervaart area) were apparently not attractive anymore from the Metal Ages onwards. Indeed, to determine the suitability of a certain land type for a certain activity, it is necessary to understand the different types of land use (hunting-gathering, farming, …), the soil characteristics and the environment at different time intervals. During a large field campaign, a 70m long trench was dug through the deepest part of the former Moervaart lake, revealing alternating layers of (organic) lake marl and peat(y clay) indicating warmer/colder and drier/wetter phases. In addition, 15 mechanical corings have been made at four different locations within the depression, in large palaeochannels that cross the palaeolake, and on its borders. Both trench and corings were extensively sampled for palaeoenvironmental and sedimentological analyses and for OSL and 14C-dating. We present here the first results of the palaeoecological (mainly palynology, but also plant macroremains, charcoal, diatoms, ostracods, mollusks, beetles and Chironomideae) and sedimentological (water content, LOI, magnetic susceptibility, gamma-density) approaches, which provide new insights in the palaeolandscape evolution of this area during the Late Glacial and the early Holocene, in order to evaluate in detail how and to which degree this evolution determined the pre- and protohistoric occupation and exploitation within Sandy Flanders. Furthermore, significant emphasis is placed on the impact of prehistoric populations on both regional and local landscapes.

Court-Picon, Mona; Polfliet, Tim; Serbruyns, Lynn; de Smedt, Phillippe; Zwertvaegher, Ann; Bats, Machteld; de Reu, Jeroen; Werbrouck, Ilke; Verniers, Jacques; Crombe, Philippe

2010-05-01

329

Seismic Stratigraphy of the Mariana Forearc Sedimentary Basin  

NASA Astrophysics Data System (ADS)

A grid of seismic reflection profiles across the Mariana forearc between 14N-18N reveals a sedimentary basin between the Oligocene-Miocene frontal arc and the Eocene outer forearc highs. We identify and correlate several seismic stratigraphic units and use them to constrain the local and regional tectonics, which vary significantly from north to south. Four major sediment packages are distinguished in the southern forearc basin. The oldest unit, U-4, is conformable to arcward-tilted, rotated fault blocks formed during early extension, possibly associated with early Oligocene rifting prior to Parece Vela Basin spreading. Onlap relationships between the oldest sedimentary units indicate that deposition occurred before, during and after block rotation. On one profile, the U-4 sequence is deformed above a blind thrust fault in an otherwise extensional environment. Sediments that comprise the third unit, U-3, thin trenchward and onlap onto U-4. U-2 sediments onlap both sides of the basin and are characterized by nearly uniform thicknesses across the southern section. They currently dip trenchward, but are bypassed and onlapped arcward by thin recent deposits, U-1, on the three southern lines, suggesting recent relative subsidence of the outer forearc. The onset of this subsidence (during deposition of the upper strata of U-2) may have generated slope instability that triggered a large submarine slump off the frontal arc high into the forearc basin ENE of Saipan. The seismic stratigraphic units reveal both pre- and post-slump depositional boundaries including a possible post-slump debris apron around the perimeter of the toe thrust. The central region (near 16N), absent of the large rotated basement fault blocks found in the south, is characterized by high-angle normal faults that offset the seafloor by as much as 200 m. The upper section of U-4 is visible in isolated sections, but the coherency of the oldest layers is lost. Because a clear basement reflection is not resolved in this area, it is uncertain whether the absence of the oldest sediment reflections represents a lack of deposition or the limits of our imaging capabilities. The basin stratigraphy reveals a northward thickening of U-2 and U-3, indicating greater extension and increased sediment supply in the central region during deposition. U-1 is absent suggesting that the large relative subsidence of the outer forearc is restricted to the southern region. The stratigraphy of the northern forearc basin (near 18N) is interrupted by several local basement highs. U-4 and the lower sediments of U-3 are not imaged in this area. The upper strata of U-3 are resolvable in small basins formed between local highs. Above this, U-2 comprises most of the coherent basin fill. Ongoing work seeks to correlate these sequences with dated cores drilled in the area at ODP Leg 60 Sites 458 and 459.

Chapp, E.; Taylor, B.; Oakley, A.; Moore, G.

2005-12-01

330

Bacterial community structure in aquifers corresponds to stratigraphy  

NASA Astrophysics Data System (ADS)

So far, groundwater microbiology with respect to different host rocks has not been well described in the literature. However, factors influencing the communities would be of interest to provide a tool for mapping groundwater paths. The Thuringian Basin (Germany) studied here, contains formations of the Permian (Zechstein) and also Triassic period of Buntsandstein, Muschelkalk and Keuper, all of which can be found to crop out at the surface in different regions. We analyzed the bacterial community of nine natural springs and sixteen groundwater wells of the respective rock formations as well as core material from the Zechstein salts. For that we sampled in a mine 3 differnet salt rock samples (carnallitite, halite and sylvinitite). To validate the different approaches, similar rock formations were compared and a consistent microbial community for Buntsandstein could be verified. Similary, for Zechstein, the presence of halophiles was seen with cultivation, isolation directly from the rock material and also in groundwater with DNA-dependent approaches. A higher overlap between sandstone- and limestone-derived communities was visible as if compared to the salt formations. Principal component analysis confirmed formation specific patterns for Muschelkalk, Buntsandstein and Zechstein for the bacterial taxa present, with some overlaps. Bacilli and Gammaproteobacteria were the major groups, with the genera Pseudomonas, Marinomonas, Bacillus, Marinobacter and Pseudoalteromonas representing the communities. The bacteria are well adapted to their respective environment with survival strategies including a wide range of salinity which makes them suitable as tracers for fluid movement below the ground. The results indicate the usefulness and robustness of the approach taken here to investigate aquifer community structures in dependence of the stratigraphy of the groundwater reservoir.

Beyer, Andrea; Möller, Silke; Neumann, Stefan; Burow, Katja; Gutmann, Falko; Lindner, Julia; Müsse, Steffen; Kothe, Erika; Büchel, Georg

2014-05-01

331

Late Quaternary stratigraphy of the eastern Gulf of Maine  

SciTech Connect

Five distinct seismic facies describe the glacial, glacial-marine and postglacial sediments in the eastern Gulf of Maine. Regional cross-sections clearly document differences in the glacial-marine and postglacial stratigraphy between basins south of Truxton Swell, and Jordan basin to its north. Till occurs throughout the region as a thin veneer within basins, but thickens significantly over the ridges and swells separating basins. The ubiquitous presence of till suggests grounded ice occupied this area some time in the recent past. Ice-proximal glacial-marine (PGM) facies sediments of varying thickness mantle the entire area, occurring as a draped unit over pre-existing topography. Transitional glacial-marine (TGM) facies also occur as a draped unit, but they show onlap onto basin margins. Sediments of the TGM facies are restricted to areas south of Truxton Swell. Ice-distal glacial-marine (DGM) facies sediments also mantle the entire area, but they occur primarily as a ponded, infilling unit. The nature and distribution of these glacial-marine facies within the eastern Gulf of Maine documents changes in the environment of deposition during deglaciation. In the authors model PGM facies sediments are considered to represent settling through the water column of coarse material from the base of an ice shelf. TGM facies sediments indicate retreat of this ice margin coupled with calving of large icebergs with significant amounts of coarse debris, DGM facies sediments indicate further retreat of the ice margin and a lessening of the influence of icebergs. Stepwise ice-margin retreat from south to north through a series of grounding lines and associated pinning points is evident by these time transgressive sedimentary facies that can be correlated across the region.

Bacchus, T.S. (Univ. of Maine, Orono, ME (United States). Oceanography Dept.); Belknap, D.F. (Univ. of Maine, Orono, ME (United States). Geology Dept.)

1993-03-01

332

Stratigraphy, Structure, and Ore Deposits of the Southern Limb of the Midcontinent Rift System  

NSDL National Science Digital Library

This site features an overview of the Midcontinent Rift system of North America, an area that extends for more than 2000 km northeasterly from Kansas, through the Lake Superior region, and then southeasterly through lower Michigan. This summary of the stratigraphy, structure, and mineralization of rift rocks provides an overview of the geologic history in northern Wisconsin and upper Michigan. Separate sections describe the tectonic history and structural features of the area, the stratigraphy of volcanic and sedimentary deposits, and the mineralization that produced rich copper and silver deposits. Information is supported by numerous citations while maps and diagrams help illustrate the concepts.

T. Bornhorst

333

Reconstruction of Holocene coastal depositional environments based on sedimentological and palaeontological analyses, Zakynthos Island, Western Greece Mediterranean Sea  

NASA Astrophysics Data System (ADS)

Zakynthos Island is one of the most seismically active regions in Europe and the Holocene coastal depositional environments were influenced both by tectonic activity and sea level rise. In the present study detailed sedimentological, palaeontological and 14C dating analyses were used in order to reconstruct the Holocene coastal depositional environments as well as the different rates of sedimentation, based on data from three cores up to 30 m deep. The results of the analyses indicate changes in depositional environments from marine to brackish lagoonal and lagoon / barrier systems with temporary intrusions of marine water via storms or tsunamigenic events. High sedimentation rates in coastal areas of Zakynthos Island correspond well to the most widespread Holocene warm and humid phases. The interpretation of the sedimentological environments reveals that Zakynthos Island before 8300 BP was constituted by two islands, where the present southern part of the island was separated from the northern one by a shallow and narrow sea channel.

Avramidis, Pavlos; Iliopoulos, George; Papadopoulou, Penelope; Nikolaou, Konstantinos; Kontopoulos, Nikolaos; Wijngaarden, Gert

2014-05-01

334

Petrology, diagnosis, and sedimentology of oil reservoirs in Upper Cretaceous Shannon Sandstone Beds, Powder River basin, Wyoming  

SciTech Connect

This paper reports on a study of the petrology of the Shannon Sandstone Member that indicates diagenetic alterations of outcrop and near-surface sandstones cannot be used to predict the diagenesis of deeply buried sandstones. Textural relations show that oil migrated to reservoirs late in the postdepositional history of the Shannon. Petrologic and sedimentologic data suggest that an alternative depositional model (for example, a nearshore rather than mid-shelf setting) should be considered for the Shannon.

Hansley, P.L.; Whitney, C.G.

1990-01-01

335

A remarkable fossiliferous mass flow deposit in the Eocene Eckfeld Maar (Germany)—sedimentological, taphonomical, and palaeoecological considerations  

Microsoft Academic Search

The distal part of a mass flow deposit has been excavated across an area of 400 m2 in the basinal facies of the Eckfeld Maar. The high concentration and diversity of fossils in mainly excellent preservation (i.e. leaves, fruits\\/seeds, wood, molluscs, vertebrate teeth, and bones such as undeformed sculls) is unique and underline its outstanding importance concerning sedimentological, taxonomical, and palaeoecological

Markus Sachse

2005-01-01

336

Sedimentology and diagenesis of misoa C-2 reservoir, VLE-305/326 area, block V, Lamar Field, Maracaibe Lake, Venezuela  

SciTech Connect

The main purpose of this study was to characterize the Upper Eocene C-2 reservoir using sedimentological, petrophysical and biostratigraphic parameters. The reservoir quality was evaluated by defining its physical attributes, geometry, areal distribution and orientation, from facies analysis of sedimentary units identified in core samples. In evaluating the sedimentary features of the Misoa C-2 reservoir in VLE 305/326 area, Block V, Lamar Field, Maracaibo Lake, 2,000' of cores from five wells (named VLe-339, VLE-720, VLE -723, VLe-754, LPG-1211) were analyzed. The sedimentary sequence studied represents upper-middle deltaic plain deposits with no marine influence. These deposits were identified as interdistributary channels, crevasse splays and interdistributary bays deposited in a northward prograding system. Seven sedimentary facies were defined from the physical, chemical and biological features observed in all cores. These facies were petrophysically and petrographically characterized then grouped in six sedimentary units which were then correlated over the entire area. One hundred well logs were correlated using sedimentological criteria. Finally, four flow units were identified in the reservoir using the sedimentological parameters, petrophysical data and production behavior. A surface trend analysis program utilizing thickness values resulted in contours, trends, residuals and isometry maps of each unit with a generalized southwest-northeast trend orientation. It was determined that facies distribution in the units controls the reservoir quality. These results are the main input into reservoir simulation. An accurate reservoir modeling is needed to prepare for optimizing secondary oil recovery.

Cabrera de Casas, L.; Chacartegui, F. (Maraven S.A., Caracas (Venezuela))

1993-02-01

337

Preliminary Investigation of Linkages Between Arctic Pingos and Subsurface Stratigraphy  

NASA Astrophysics Data System (ADS)

This NASA-SETI supported study investigates the distribution of pingos (elliptically-shaped ice-rich topographic mounds) across 2300 square kilometers of the central coastal plain of Arctic Alaska in relation to the shallow geological framework that exists immediately beneath them. Pingos in the central North Slope of Alaska are classified as being of the closed or hydrostatic type. Their genesis is often assigned to freezing and cryogenic uplift of near-surface saturated thaw lake sediments that are exposed as lakes are drained and/or become choked with sediments. Although thaw lakes appear rather ubiquitous across the study area, pingos do not. Pingo distributions can be categorized as either clusters of elements or as relatively dispersed. Spatial statistical analysis reveals that pingo distribution is non-random and clustered. The analysis also took into account that pingo distribution is a function of preferential preservation between modern rivers channels that cross the study area. Pingo distributions and frequency were tested in relation to the location and type of stratigraphic and sedimentological features that characterized the shallow subsurface across the study area. Subsurface interpretation was derived mostly from oil well wireline logs. Gamma ray logs for more than 160 wells were used to define, correlate and assess the connectivity and conductivity of shallow and near-surface stratigraphic units between wells. Assessed also were major facies changes and the type and locations of subsurface structures such as major basement-to-surface faults and folds. The surface and near-surface truncation and subcropping of tilted, alternating units of permeable coarse-grained and confining fine- grained units were also mapped in relation to pingo locations. Preliminary and intriguing findings will be presented which contribute to the hypothesis that pingo genesis, location, and variations in morphology could be, in part, linked to a well-documented and active subsurface geohydrologic system. This system is characterized by multiple stacked hydrocarbon-, saline- and freshwater-rich reservoirs. Processes include fault reactivation and basin subsidence that drive episodic basin expulsion, and upward migration and mixing of deep basin and phreatic fluids along basin margins. Endpoints of the system include demonstrable gas hydrates deposits that occur below and within the permafrost, and documented seepage of hydrocarbons and groundwater at the surface. Our hypothesis entertains the idea that closed pingos might also be endpoints of the petroluem system as basin and phreatic fluids migrate vertically within a thick and leaky permafrost interval along faults and tilted reservoir sand-rich units, which intersect and differentially charge frozen near-surface sedimentary units. Future field-based sampling and geophysical studies may shed additional light on this model's application for pingo genesis and resource exploration on Mars.

Casavant, R.; Skirvin, S.; Patel, C.; Burr, D.

2008-12-01

338

Early Triassic magnetic polarity time scale—integration of magnetostratigraphy, ammonite zonation and sequence stratigraphy from stratotype sections (Canadian Arctic Archipelago)  

NASA Astrophysics Data System (ADS)

Stratotypes defining the stages of the Early Triassic (Griesbachian, Dienerian, Smithian and Spathian) are located on Ellesmere and Axel Heiberg islands in the northern Canadian Arctic. Ammonite-rich horizons are within a clastic outer shelf-to-slope facies of thick progradational wedges of mudstones and siltstones. Three sections were sampled for magnetostratigraphy and interpreted for transgressive and regressive pulses of sedimentation. Using the ammonite zonation as a guide, the transgressive-regressive cycles and magnetostratigraphies have been correlated among the sections and to the published Triassic sequence stratigraphy time scale, thus enabling definition of the magnetic polarity pattern for the upper Griesbachian to Smithian stages in multiple sections. The magnetic polarity and associated sequence stratigraphy pattern for the lower Griesbachian and for the Spathian were derived from single sections. The Griesbachian and Dienerian stages each have two pairs of normal- and reversed-polarity chrons; the Smithian is predominantly of normal polarity, and the Spathian is predominantly of reversed polarity. This magnetic polarity time scale may help to resolve age correlations of North American redbed facies and to define the Permian-Triassic boundary. After correction for variable structural orientations, the mean directions of magnetization from the three sites converge at 296° declination, 57° inclination ( k = 60, ? 95 = 16.5° ; equivalent pole = 41°N, 161°E; paleolatitude = 38°N), which is consistent with the pole derived from nearby Early Permian volcanics and supports a postulated post-Early Triassic, pre-Tertiary counterclockwise rotation of this region with respect to cratonic North America.

Ogg, James G.; Steiner, Maureen B.

1991-10-01

339

Great Salt Lake, and precursors, Utah: The last 30,000 years  

Microsoft Academic Search

Sediment cores up to 6.5 m in length from the South Arm of Great Salt Lake, Utah, have been correlated. Radiocarbon ages and volcanic tephra layers indicate a record of greater than 30,000 years. A variety of approaches have been employed to collect data used in stratigraphic correlation and lake elevation interpretation; these include acoustic stratigraphy, sedimentologic analyses, mineralogy, geochemistry

Ronald J. Spencer; M. J. Baedecker; H. P. Eugster; R. M. Forester; M. B. Goldhaber; B. F. Jones; K. Kelts; J. McKenzie; D. B. Madsen; S. L. Rettig; M. Rubin; C. J. Bowser

1984-01-01

340

On the potential sedimentological origin of downcore variations of bulk sedimentary ? 15N  

NASA Astrophysics Data System (ADS)

ODP site 1144 is located less than ten kilometers from core site SONNE 17940 on the continental slope of the northern South China Sea (SCS). Despite their proximity, the sedimentary nitrogen isotope records are distinctly different at both sites, with glacial-interglacial variations of ca. 1 permil at site 17940, and up to 4 permil at site ODP1144. Here we explore the potential origin of these differences in the ? 15N records, focussing on three aspects of the variable sedimentology at both sites on glacial-interglacial timescales. 1) Based on major element contents (Si/Al and Zr/Al ratios), glacial sediments at site ODP1144 are significantly finer-grained than at site 17940. As evident from a suite of samples from the SCS, finer-grained sediments are associated with higher ? 15N values, thus contributing to the offset in the ? 15N records between both sites. 2) Sediments at site ODP1144 contain lower amounts of potassium, and, by inferrence, ammonium, which substitutes for potassium in K-bearing minerals. Given the low ? 15N of ammonium fixed in clay minerals this difference in mineralogy further contributes to lower glacial ? 15N values at site 17940 compared to ODP1144. 3) We will also be presenting radiocarbon dates of total organic carbon (TOC), in an attempt to elucidate the different origin and sedimentological history of TOC at both sites. Sediments found at both ODP1144 and 17940 originate from an area affected by eustatic sediment redistribution, gravity- and fluvially-driven sediment mobilization from the broad northern SCS continental shelf. Rare earth element analyses (Shao et al., 2001) indicate that a significant part of the detrital material at ODP1144 originates from Taiwan, transported through the Penghu channel to the coring site in the northern SCS, and is not representative of the vertical particle flux to the sea floor. Sediment redistribution therefore potentially affects downcore variations in bulk sedimentary ? 15N, and cautions the interpretation of a single downcore record with respect to local/regional ? 15N variations in the past, and indeed with respect to other sedimentary proxies.

Kienast, M.; Higginson, M. J.; Mollenhauer, G.; Eglinton, T. I.; Calvert, S. E.

2003-12-01

341

A re-analysis of the Late Bronze Age eruption and tsunami of Santorini, Greece, and the implications for the volcano–tsunami hazard  

Microsoft Academic Search

The paroxysmal eruption of Santorini (ca. 3500 BP), referred to as the Late Bronze Age (LBA) eruption, probably generated multiple tsunami; their occurrence and impacts being cited frequently in scientific papers and articles. This paper examines what is known about any LBA tsunami, noting possible mechanisms of generation and identifying sedimentological traces. Firstly, the eruption sequence is outlined providing the

Dale Dominey-Howes

2004-01-01

342

Stratigraphy and multi-phase tectonic history of the Chukchi Borderland from MCS data  

NASA Astrophysics Data System (ADS)

The Chukchi Edges project was designed to establish the relationship between the Chukchi Shelf and Borderland and indirectly test theories of opening for the Canada Basin. During this cruise, ~5300 km of 2D multi-channel seismic profiles and other geophysical measurements (swath bathymetry, gravity, magnetics, sonobuoy refraction seismic) were collected from the RV Marcus G. Langseth across the transition between the Chukchi Shelf and Chukchi Borderland. These profiles reveal extended basins separated by faulted high-standing blocks. Basin stratigraphy can be subdivided on the basis of gross stratal geometry, reflection terminations and inferred unconformities. The wedge-shaped synrift sequences terminate against the basement highs and/or major faults, burying the basement topography. The inferred postrift seismic units are more nearly tabular, but thicken locally due to compaction of underlying synrift sediments. Reflection character is dominated by alternating high and low amplitude continuous reflectors which may be consistent with pelagic or turbidite sediments. Chaotic units are also observed, which may indicate mass-flow deposits. The truncated sediments over the basement highs of the Chukchi Shelf, Chukchi Plateau and Northwind Ridge suggest major erosion due both to glacial planation and earlier erosional events perhaps associated with basement uplift prior to or during rifting and extension. It is believed that the bulk of the synrift sediments are Mesozoic in age. Certainly Cenozoic sediments are also preserved in these basins, but the position of the boundary is uncertain. Locally, continuous reflectors are observed underlying the rift basin fill. These older units, of very uncertain age, would, if sampled, provide constraint on the history and affinities of the Chukchi Borderland. In addition to the extensional basins, a number of small symmetric basins are observed on the flanks of the Chukchi Plateau. These basins may be transtensional and argue for a 2nd phase of tectonism, which overprinted the obvious extensional fabric of the Borderland. This is supported by the observation of uplifted postrift sediments on the flanks of some of the intermedial basement highs.

Ilhan, I.; Coakley, B.

2012-12-01

343

After a century-Revised Paleogene coal stratigraphy, correlation, and deposition, Powder River Basin, Wyoming and Montana  

USGS Publications Warehouse

The stratigraphy, correlation, mapping, and depositional history of coal-bearing strata in the Paleogene Fort Union and Wasatch Formations in the Powder River Basin were mainly based on measurement and description of outcrops during the early 20th century. Subsequently, the quality and quantity of data improved with (1) exploration and development of oil, gas, and coal during the middle 20th century and (2) the onset of coalbed methane (CBM) development during the late 20th and early 21st centuries that resulted in the drilling of more than 26,000 closely spaced wells with accompanying geophysical logs. The closeness of the data control points, which average 0.5 mi (805 m) apart, made for better accuracy in the subsurface delineation and correlation of coal beds that greatly facilitated the construction of regional stratigraphic cross sections and the assessment of resources. The drillhole data show that coal beds previously mapped as merged coal zones, such as the Wyodak coal zone in the Wyoming part of the Powder River Basin, gradually thinned into several discontinuous beds and sequentially split into as many as 7 hierarchical orders westward and northward. The thinning and splitting of coal beds in these directions were accompanied by as much as a ten-fold increase in the thicknesses of sandstone-dominated intervals within the Wyodak coal zone. This probably resulted from thrust loading by the eastern front of the Bighorn uplift accompanied by vertical displacement along lineaments that caused subsidence of the western axial part of the Powder River Basin during Laramide deformation in Late Cretaceous and early Tertiary time. Accommodation space was thereby created for synsedimentary alluvial infilling that controlled thickening, thinning, splitting, pinching out, and areal distribution of coal beds. Equally important was differential subsidence between this main accommodation space and adjoining areas, which influenced the overlapping, for example, of the Dietz coal zone in Montana, over the Wyodak coal zone in Wyoming. Correlation in a circular track of the Wyodak coal zone in the southern part of the basin also demonstrates overlapping with lower coal zones. Recognition of this stratigraphic relationship has led to revision of the correlations and nomenclature of coal beds because of inconsistency within these zones as well as those below and above them, which have long been subjects of controversy. Also, it significantly changes the traditional coal bed-to-bed correlations, and estimates of coal and coalbed methane resources of these coal zones due to thinning and pinching out of beds. More notably, thickness isopach, orientation, and distribution of the merged Wyodak coal bodies in the south-southeast part of the basin suggest that differential movement of lineament zones active during the Cretaceous was not a major influence on coal accumulation during the Paleocene. Improved knowledge of alluvial depositional environments as influenced by external and internal paleotectonic conditions within the Powder River Basin permits more accurate correlation, mapping, and resource estimation of the Fort Union and Wasatch coal beds. The result is a better understanding of the sedimentology of the basin infill deposits in relation to peat bog accumulation.

Flores, Romeo M.; Spear, Brianne D.; Kinney, Scott A.; Purchase, Peter A.; Gallagher, Craig M.

2010-01-01

344

High-resolution sedimentological and subsidence analysis of the Late Neogene, Pannonian Basin, Hungary  

USGS Publications Warehouse

Detailed sedimentological and paleontological analyses were carried out on more than 13,000 m of core from ten boreholes in the Late Neogene sediments of the Pannonian Basin, Hungary. These data provide the basis for determining the character of high-order depositional cycles and their stacking patterns. In the Late Neogene sediments of the Pannonian Basin there are two third-order sequences: the Late Miocene and the Pliocene ones. The Miocene sequence shows a regressive, upward-coarsening trend. There are four distinguishable sedimentary units in this sequence: the basal transgressive, the lower aggradational, the progradational and the upper aggradational units. The Pliocene sequence is also of aggradational character. The progradation does not coincide in time in the wells within the basin. The character of the relative water-level curves is similar throughout the basin but shows only very faint similarity to the sea-level curve. Therefore, it is unlikely that eustasy played any significant role in the pattern of basin filling. Rather, the dominant controls were the rapidly changing basin subsidence and high sedimentation rates, together with possible climatic factors.

Juhasz, E.; Muller, P.; Toth-Makk, A.; Hamor, T.; Farkas-Bulla, J.; Suto-Szentai, M.; Phillips, R.L.; Ricketts, B.

1996-01-01

345

Workshop on the Martian Northern Plains: Sedimentological, periglacial, and paleoclimatic evolution  

NASA Technical Reports Server (NTRS)

The penultimate meeting in the Mars Surface and Atmosphere Through Time (MSATT) series of workshops was held on the campus of the University of Alaska in Fairbanks, Alaska, 12-13 Aug. 1993. This meeting, entitled 'The Martian Northern Plains: Sedimentological, Periglacial, and Paleoclimatic Evolution,' hosted by the Geophysical Institute at the University of Alaska, was designed to help foster an exchange of ideas among researchers of the Mars science community and the terrestrial glacial and periglacial science community. The technical sessions of the workshop were complemented by field trips to the Alaska Range and to the Fairbanks area and a low-altitude chartered overflight to the Arctic Costal Plain, so that, including these trips, the meeting lasted from 9-14 Aug. 1993. The meeting, field trips, and overflight were organized and partially funded by the Lunar and Planetary Institute and the MSATT Study Group. The major share of logistical support was provided by the Publications and Program Services Department of the Lunar and Planetary Institute. The workshop site was selected to allow easy access to field exposures of active glaciers and glacial and periglacial landforms. In all, 25 scientists attended the workshop, 24 scientists (plus 4 guests and the meeting coordinator) participated in the field trips, and 18 took part in the overflight. This meeting reaffirmed the value of expertly led geologic field trips conducted in association with topical workshops.

Kargel, J. S. (editor); Parker, T. J. (editor); Moore, J. M. (editor)

1993-01-01

346

Sedimentology and petroleum occurrence, Schoolhouse Member, Maroon Formation (Lower Permian), northwestern Colorado  

SciTech Connect

The Lower Permian Schoolhouse Member of the Maroon Formation (formerly considered the Schoolhouse Tongue of the Weber Sandstone) forms a partly exhumed petroleum reservoir in the Eagle basin of northwestern Colorado. The Schoolhouse consists mainly of yellowish gray to gray, low-angle to parallel bedded, very fine to fine-grained sandstone of eolian sand-sheet origin; interbedded fluvial deposits are present in most sections. The sand-sheet deposits of the Schoolhouse Member are sedimentologically and petrologically similar to those in the underlying red beds of the main body of the Maroon Formation, and the Schoolhouse is considered the uppermost sand sheet in the Maroon depositional sequence. The bleached and oil-stained Schoolhouse member is distinguished from the underlying Maroon red beds on the basis of its diagenetic history, which is related to regional hydrocarbon migration and development of secondary porosity. Geological and geochemical data suggest that Schoolhouse Member oils have upper Paleozoic sources, including the intrabasinal Belden Formation. 13 figs., 1 tab.

Johnson, S.Y.; Schenk, C.J.; Anders, D.L.; Tuttle, M.L. (Geological Survey, Denver, CO (USA))

1990-02-01

347

Variation in sedimentology and architecture of Eocene alluvial strata, Wind River and Washakie basins, Wyoming  

SciTech Connect

Eocene continental, alluvial strata of the Wind River Formation (Wind River Basin) and the Cathedral Bluffs Member of the Wasatch Formation (Washakie basin) provide two examples of Laramide intermontane basin aggradation. These alluvial sediments primarily represent overbank flood deposits marginal to channel complexes. Their sedimentology and architecture, although grossly similar, appear to vary somewhat with proximity to Laramide uplifts. In both cases, repetitive sedimentation on the floodplain produced a succession of depositional couplets, each composed of a light-gray sand overlain by a red clay-rich silt or sand. The lower sands are tabular bodies that, near their distal margins, taper discernibly. They commonly display planar and ripple-drift laminations. Upper clay-rich layers, which are laminated, are also generally tabular. Those floodplain strata depositional proximal to Laramide uplifts show little evidence of scouring prior to deposition of the next, overlying couplet. Most of these sedimentary layers, therefore, are laterally continuous (up to 2 km). This alluvial architecture results in relatively uniform porosity laterally within depositional units but variable porosity stratigraphically through the sequence. In contrast, alluvial sediments deposited farther from the Laramide uplifts have undergone sporadic incision (either during rising flood stage or subsequently) followed by aggradation. As a result, many of these floodplain couplets are discontinuous laterally and, hence, exhibit large-scale lateral variability in porosity. Both alluvial sequences have undergone similar types and extents of burial diagenesis.

Patterson, P.E.; Larson, E.E. (Univ. of Colorado, Boulder (United States))

1991-03-01

348

Sedimentology and diagenesis of a rift basin lacustrine sandstone: Pematang group, central Sumatra, Indonesia  

SciTech Connect

The Central Sumatra basin is a back-arc basin that formed during the Paleocene as a series of half-graben structures. These early formed half-graben structures were filled with nonmarine clastics and lacustrine sediments of the Pematang Group, sourced from local highland areas. The Pematang Group consists of the Lower Red Beds, Brown Shale, Coal Zone Member, and Lake Fill Formation (in ascending order). The Pematang Group sedimentology is intimately related to the regional and basinal tectonic development and history. Sandstones of the Pematang Group are predominantly sublitharenites and litharenites; feldspars are rare. Sandstone diagenesis is relatively uniform regardless of the depositional environment. Diagenetic modifications include compaction, early calcite and dolomite cementation, quartz overgrowth formation, unstable rock-fragment dissolution, kaolinite precipitation, siderite formation, and local illite formation. Secondary porosity accounts for up to 50% of the effective porosity and was created by rock-fragment dissolution. This dissolution is probably caused by the organic acids released during kerogen maturation. Stable isotope data from diagenetic siderite are presented.

Janks, J.S.; Kelley, P.A.; Williams, H.H.

1986-05-01

349

Reservoir sedimentology of the M. Triassic Halfway Fm. , Wembley field, Alberta  

SciTech Connect

The Middle Triassic Halfway Formation of west-central Alberta is interpreted as a prograding barrier island shoreline deposit. A detailed sedimentological study based on 130 cored sequences and 300 well logs in the Wembley area (Townships 72-73, Ranges 7-9, West of Sixth Meridian) has enabled the author to delineate the geometry of reservoir units, interpreted as tidal inlet fill, upper shoreface, and flood-tidal delta sandstones. Complete shoreface sequences average 15 m in thickness and form mappable trends tens of kilometers along depositional strike, but are only continuous for a few kilometers across dip, with the intervening areas having been reworked by one or more migrating tidal inlets. The strike-elongate inlet-fill sequences cover more than 50% of the field area. They are typically 10 m thick and exhibit the best porosities due to leaching of bioclastic material in the lower part of the fill, but the down-cutting of successive inlets makes the reservoir sands laterally discontinuous. Inlet sands extend up-dip into flood-tidal delta sandbodies that average 4 m in thickness and pinch out in lagoonal muds. Although showing much greater lateral continuity than the other reservoir units, the upper shoreface sandstones do not exhibit biomoldic porosity and are a less productive unit. Such an understanding of the architecture of the various reservoir components present in a barrier island shoreline system is essential when planning a secondary recovery program.

Willis, A.J. (Univ. of Alberta, Edmonton (Canada))

1991-03-01

350

Sequence stratigraphy of Jurassic strata in the lower Surat Basin succession, Queensland  

Microsoft Academic Search

The principles of non-marine sequence stratigraphy were applied to the Jurassic strata in the lower part of the Surat Basin, in order to better determine the depositional history of the basin and highlight potential reservoir and source rocks. The lithostratigraphic units in the Early-early Late Jurassic interval can be divided into three supersequences: J, K and L. Each supersequence consists

K. L. Hoffmann; J. M. Totterdell; O. Dixon; G. A. Simpson; A. T. Brakel; A. T. Wells; J. L. Mckellar

2009-01-01

351

Jurassic-Cretaceous continental margin of Southeastern Russia: Outcrop sequence stratigraphy, sedimentation and tectonics  

Microsoft Academic Search

Data on the composition and distribution of the sedimentary complexes of the Late Mesozoic continental margin of Southeastern Russia and their boundaries permit reconstruction of the tectonic evolution stages using different units of outcrop sequence stratigraphy separated by unconformities. Four siliciclastic megasequences extending from the Bureya ancient massif (microcontinent) to Sakhalin have been recorded within the Jurassic-Cretaceous continental margin of

Kirillova

2009-01-01

352

Seismic stratigraphy of the western Florida carbonate platform above the Mid-Cretaceous sequence boundary (MCSB)  

Microsoft Academic Search

From the Apalachicola Basin (AB) to the Sarasota Arch, a web of multifold seismic and 29 wells were analyzed to determine Upper Cretaceous-Cenozoic stratigraphy. Concordant reflection geometries above and below the MCSB throughout most of the study area do not suggest prolonged subaerial exposure of the platform as some have considered. The configuration of the MCSB surface influenced the distribution

Jee

1993-01-01

353

Equivalent hydraulic conductivity of an experimental stratigraphy: Implications for basin-scale flow  

E-print Network

Equivalent hydraulic conductivity of an experimental stratigraphy: Implications for basin-scale groundwater flow models are the estimation of representative hydraulic conductivity for the model units. In this study, high-resolution, fully heterogeneous basin-scale hydraulic conductivity map is generated

Gable, Carl W.

354

C-Isotope stratigraphy, a monitor of paleoenvironmental change: A case study from the early cretaceous  

Microsoft Academic Search

Today's disturbance of the global carbon cycle induced by anthropogenic processes has raised new interest in the history of the global carbon cycle and its relationship to climate and other geochemical cycles. Carbon-isotope stratigraphy proves to be most useful as a monitor of the history of the carbon-cycle during the last 200 million years. In the introductory paragraphs of this

Helmut Weissert

1989-01-01

355

Foraminifera, sequence stratigraphy and regional correlation; an example from the uppermost Albian of Southern England  

Microsoft Academic Search

While the general principles of sequence stratigraphy are well-established, the detailed distribution of fossils within sequences is less well known. Emery & Myers (1996) indicate that the most distinctive palaeontological information comes from the Maximum Flooding Surface where diverse assemblages, often dominated by planktonic taxa, are characteristic. The palaeontological features of a number of sequences in the uppermost Albian of

Malcolm B. Hart

2000-01-01

356

Stratigraphy, paleoceanography, and evolution of Cretaceous Pacific guyots; relics from a greenhouse Earth  

Microsoft Academic Search

Many guyots in the north Pacific are built of drowned Cretaceous shallow-water carbonates that rest on edifice basalt. Dating of these limestones, using strontium- and carbon-isotope stratigraphy, illustrates a number of events in the evolution of these carbonate platforms: local deposition of marine black shales during the early Aptian oceanic anoxic event; synchronous development of oolitic deposits during the Aptian;

HUGH C. JENKYNS; PAUL A. WILSON

1999-01-01

357

Catoctin volcanic province: the bearing of stratigraphy and geochemistry on petrogenesis  

Microsoft Academic Search

The late Precambrian flood basalts of the Catoctin Volcanic Province in the central Appalachians are predominantly tholeiitic in composition, mostly aphyric and lack any trace of olivine. Recent mapping of two transects across the Blue Ridge in Virginia has shown a well preserved flow stratigraphy and fabric. In the southern transect, near Waynesboro, Virginia, flows are generally 1-30 meters thick,

R. L. Badger; A. K. Sinha

1985-01-01

358

PALEOCENE-LOWERMOST SEQUENCE STRATIGRAPHY OF THE NEW JERSEY COASTAL PLAIN  

E-print Network

PALEOCENE-LOWERMOST SEQUENCE STRATIGRAPHY OF THE NEW JERSEY COASTAL PLAIN by ASHLEY D. HARRIS A thesis submitted to the Graduate School-New Brunswick Rutgers, The State University of New Jersey by ________________________ ________________________ ________________________ New Brunswick, New Jersey January, 2007 #12;ii ABSTRACT OF THESIS PALEOCENE-LOWERMOST EOCENE SEQUENCE

359

Integrated Late Santonian-Early Campanian sequence stratigraphy, New Jersey Coastal Plain  

E-print Network

Integrated Late Santonian-Early Campanian sequence stratigraphy, New Jersey Coastal Plain section (Merchantville Formation) in two coreholes (Ancora and Bass River) from the New Jersey coastal-and biostratigraphic analyses of the Merchantville Formation sequences in four New Jersey coastal plain coreholes (Sea

360

Contaminant Stratigraphy of the Ballville Reservoir, Sandusky River, NW Ohio: Implications for Dam Removal  

E-print Network

Contaminant Stratigraphy of the Ballville Reservoir, Sandusky River, NW Ohio: Implications for Dam Green, Ohio 43403 ABSTRACT. The Ballville Dam (Sandusky River) is one of the major structures in the Lake Erie water- shed, impounding 1.7 million m3 of water and sediment. Removal of the dam would open

Gottgens, Hans

361

The nature and significance of condensed sections in Gulf Coast late Neogene sequence stratigraphy  

Microsoft Academic Search

Sequence stratigraphic analysis is being applied in the Gulf Coast to facilitate genetic interpretations of stratigraphy and to improve predictions of reservoir facies. Among the components of sequences, the condensed section is of paramount importance in providing a chronostratigraphic framework and in the delineation of systems tracts. Condensed sections are characterized by abundant and species diverse planktonic foraminiferal and calcareous

Bernard L. Shaffer

1990-01-01

362

Sequence-stratigraphic and mass-balance analysis of experimental stratigraphy  

NSDL National Science Digital Library

Sequence-stratigraphic and mass-balance analysis of experimental stratigraphy. Students are charged with evaluating how basin subsidence geometry influences depositional patterns. In addition to providing practice applying sequence-stratigraphic methods, this project builds quantitative data-analysis and writing skills.

Liz Hajek

363

Precise Dating of FloodPlain Stratigraphy Using Changes in Tree-Ring Anatomy Following Burial  

Microsoft Academic Search

Determination of sediment deposition rates from stratigraphy is typically limited by a scarcity of chronological information. We present a method for precise dating of sedimentary beds based on the change in anatomy of tree rings upon burial. When stems of tamarisk (Tamarix ramosissima)and sandbar willow (Salix exigua) are buried, subsequent annual rings in the buried portions become narrower and vessels

J. M. Friedman; P. B. Shafroth; K. R. Vincent; M. L. Scott; G. T. Auble

2001-01-01

364

Stratigraphy and infill history of the glacially eroded Matane River Valley, eastern Quebec, Canada  

E-print Network

ARTICLE Stratigraphy and infill history of the glacially eroded Matane River Valley, eastern Quebec. This paper presents a model of the evolution of the Matane River Valley, which in many points is similar to existing conceptual fjord-valley fill models. Résumé : Des terrasses dans la partie aval de la vallée de la

365

Sorting out meandering and braiding: discriminating formative conditions and stratigraphy  

NASA Astrophysics Data System (ADS)

For various river channel patterns, the necessary formative conditions differ, but how is not entirely understood. Furthermore, not only the morphology and dynamics differ, but also the resulting stratigraphy differs, of which understanding is required to infer past environmental conditions and predict reservoir behaviour. Our objective is to identify the necessary and sufficient conditions for forming dynamic meandering and braided rivers. We reproduced both patterns experimentally and with a physics-based numerical model, and produced synthetic stratification from bed elevation maps and control lacquer peels for the experiments. Experimental meandering was produced using a mixture of poorly sorted sediment and silt-sized silica flour and a transversely moving inflow boundary. Braiding was produced in exactly the same conditions but without the silica flour. These experiments represent gravel-bed rivers in nature, where both experimental meandering and braiding channels were close to the transition between the types. Onset meandering was also produced in the numerical model (Delft3D) with a similar transversely moving inflow boundary, whilst braided rivers formed with fixed inflow or some noise on the transverse discharge distribution at the inflow boundary. The silica flour deposited on crevasse splays and in chute channels, forming new floodplain. This caused much less chute cutoffs and stronger banks. The resulting meandering river formed multiple sets of scroll bars forming pointbars, overlain by splays and floodplain. The braided river, in contrast, showed mid-channel bars and multiple active channels, faster and more haphazard bar and channel migration, and frequent chute cutoffs. Apart from the floodplain, stratification in meandering rivers consisted of sigmoidally stratified units formed by scroll bars and channel fills, usually formed after chute cutoff. Braided rivers had similar units but much smaller and more. In both cases the highest preservation potential is in the deepest channels. We conclude that some floodplain-filling sediment or vegetation is required for meandering to prevent chute cutoffs to lead to weak braiding, but, more importantly, that some dynamics are required at the upstream boundary, where periodic perturbation causes meandering whilst stochastic perturbation causes braiding. Furthermore, morphology and stratification in braided gravel-bed rivers have much smaller morphological and stratigraphic units relative to average channel width than the meandering rivers, even though active bar dimensions are comparable.

Kleinhans, M. G.; van de Lageweg, W. I.; Schuurman, F.; Van Dijk, W. M.

2011-12-01

366

The International Subcommission on Stratigraphic Classification of the International Commission on Stratigraphy: The Knowledge  

NASA Astrophysics Data System (ADS)

The International Subcommission on Stratigraphic Classification (ISSC) was born in 1955 as an effort to promote awareness of stratigraphic principles and encourage worldwide standardization of stratigraphic approaches and terminology. The first major achievement of ISSC was the 1976 publication of the International Stratigraphic Guide. It was revised in 1994, with an abridged version appearing in 1999. These documents achieved their goals magnificently: cited innumerable times and forming the core of many national stratigraphic codes. As the discipline has evolved, particularly from technological advances and ocean drilling, new tools and methodologies have been developed and these have led to ever finer resolution of geological time and ever more exact correlation of stratigraphic units and events, thereby enhancing the understanding of the genesis of the geological record. Under the leadership of M. B. Cita, ISSC embarked in 2002 on a renewed initiative to disseminate to the global geological community these newer developments, and ultimately incorporate them into a third edition of the Guide. To this aim, traditional and new branches of stratigraphy are being treated: chemostratigraphy, cyclostratigraphy, magnetostratigraphy, lithostratigraphy, sequence stratigraphy, biostratigraphy, and chronostratigraphy. An open-access review paper is dedicated to each and published in Newsletters on Stratigraphy. The next edition of the Guide will be inclusive of all branches of stratigraphy and also embrace igneous and metamorphic rocks. It is envisaged that a textbook on stratigraphy based on these papers and the revised Guide could prove a timely contribution, especially to younger generations of practitioners, and aid global communication and understanding of stratigraphic principles and methods.

Pratt, Brian

2014-05-01

367

Stratigraphy of Upper Cretaceous-Palaeogene sequences in the southern and eastern Menderes Massif (western Turkey)  

NASA Astrophysics Data System (ADS)

The stratigraphy of the uppermost levels of the Menderes Massif is controversial and within its details lie vital constraints to the tectonic evolution of south-western Turkey. Our primary study was carried out in four reference areas along the southern and eastern Menderes Massif. These areas lie in the upper part of the Menderes metamorphic cover and have a clear stratigraphic relationship and contain datable fossils. The first one, in the Akbük-Milas area, is located south-east of Bafa Lake where the Milas, then K?z?la?aç and Kaz?kl? formations are well exposed. There, the Milas formation grades upwards into the K?z?la?aç formation. The contact between the K?z?la?aç and the overlying Kaz?kl? formation is not clearly seen but is interpreted as an unconformity. The Milas and K?z?la?aç formations are also found north of Mu?la, in the region of Yata?an and Kavakl?dere. In these areas, the Milas formation consists of schists and conformably overlying platform-type, emery and rudist-bearing marbles. Rudists form the main palaeontological data from which a Santonian-Campanian age is indicated. The K?z?la?aç formation is characterized by reddish-greyish pelagic marbles with marly-pelitic interlayers and coarsening up debris flow deposits. Pelagic marbles within the formation contain planktonic foraminifera and nanoplankton of late Campanian to late Maastrichtian age. The Kaz?kl? formation is of flysch type and includes carbonate blocks. Planktonic foraminifera of Middle Palaeocene age are present in carbonate lenses within the formation. In the Serinhisar-Tavas area, Mesozoic platform-type marbles (Y?lanl? formation) belonging to the cover series of the Menderes Massif exhibit an imbricated internal structure. Two rudist levels can be distinguished in the uppermost part of the formation: the first indicates a middle-late Cenomanian age and the upper one is Santonian to Campanian in age. These marbles are unconformably covered by the Palaeocene-Early Eocene Zeybekölentepe formation with polygenetic breccias. In the Çal-Denizli area, the Menderes massif succession consists of cherty marbles and clastic rocks with metavolcanic lenses. The Lower-Middle Eocene ?alvan formation lies unconformably on this sequence and is interpreted as equivalent to the marble horizons at Serinhisar but with pelagic facies. The ?alvan formation consists of shale, mafic volcanic rock, lenses of limestone and blocks of recrystallized limestone. The ?alvan formation is dated here for the first time by Early-Middle Eocene foraminifera and nanoplankton from the matrix of the formation. An angular unconformity exists between the Upper Cretaceous and Lower Tertiary sequences, suggesting that a phase of deformation affected the southern and eastern part of the Menderes Massif at this time. This deformation may be caused by initial obduction of the Lycian ophiolite onto the passive margin to the north of the Menderes carbonate platform during the latest Cretaceous. Drowning of the platform led to termination of carbonate deposition and deposition of deep water flysch-like clastic sediments.

Özer, Sacit; Sözbilir, Hasan; Özkar, ?zver; Toker, Vedia; Sari, Bilal

2001-03-01

368

A review of Arbuckle Group strata in Kansas from a sedimentologic perspective: Insights for future research from past and recent studies  

USGS Publications Warehouse

Arbuckle Group and equivalent-age rocks (Cambrian and Lower Ordovician) represent an important record of sediment deposition in the history of the North American continent and they contain important accumulations of hydrocarbons (oil and gas) and base metal deposits. This is true for Kansas as well where Arbuckle strata account for approximately 40% of the volume of produced petroleum and known reserves. However, in comparison to their counterparts in other areas, such as the Ellenburger and Knox, Arbuckle rocks in Kansas remain relatively understudied, especially with respect to sedimentology and diagenesis. The Arbuckle is present in the subsurface in most of Kansas and is absent only in areas of northeastern and northwestern Kansas, and over ancient uplifts and buried Precambrian highs. Arbuckle rocks thicken from north to south and are up to 1,390 feet in the southeastern corner of Kansas. Arbuckle Group and equivalent-age rocks from Kansas and surrounding areas are similar, consisting of platform deposits dominated by ramp-type subtidal to peritidal carbonates (mostly dolomitized) which can be subdivided into cycles, less than 0.5 m to 40 m thick, based on facies type and depositional patterns. Recent studies from central Kansas show that major depositional facies consist of coarse-grained packstones/ grainstones, fine-grained packstones/wackestones/mudstones, stromatolites-thrombolites, intraclastic conglomerate and breccia, and shale. In addition, secondary features include dolomitization, breccia, fracture, and conglomerate related to early subaerial exposure and later karst, burial or structural processes, silicification, and local mineralization. Arbuckle and equivalent strata in the Midcontinent were affected by prolonged subaerial exposure that began immediately after Arbuckle deposition, forming the sub-Tippecanoe to sub-Absaroka unconformity. Favorable reservoir qualities generally are thought to be related directly to basement structural elements and karstic features from the post-Arbuckle subaerial exposure event. Although most production in Kansas is from the top of the Arbuckle, some early and recent studies indicate that the Arbuckle is not a simple homogeneous reservoir, that complex vertical and lateral heterogeneities exist including both nonporous and porous horizons in the formation, and that high probability exist of locating additional oil with improved reservoir characterization. Although fracture and vuggy porosity contribute importantly to the production of Arbuckle strata, recent observations indicate a significant amount of porosity (about 50%) in many cores is controlled by depositional facies and dolomitization. Studies of Arbuckle and equivalent-age strata from other areas indicate that Arbuckle strata and diagenetic processes are complex and that porosity/permeability patterns are related to a number of processes. These studies underscore the importance of continued study of Arbuckle rocks in Kansas for improved reservoir characterization. Ongoing and future geologic studies of Arbuckle rocks in Kansas are being directed toward: (1) Continued sedimentologic, stratigraphic, and sequence stratigraphic analyses incorporating core, well log, and seismic data; (2) petrophysical studies. Initial studies indicate that core plug petrophysical properties are controlled by matrix grain size and that upscalling from plug to whole-core and drill-stem test data can identify and quantify the relative contribution of karstic, fracture and matrix porosity and permeability: (3) Regional and local structural analyses and mapping of the upper Arbuckle surface to provide more details on the contribution of structural features and karst paleogeomorphology to reservoir character; and (4) diagenetic and geochemical studies focusing especially on the timing of, and processes associated with, dolomitization and karstification events and their contributions to creating or occluding porosity.

Franseen, E.K.

2000-01-01

369

Insights into the October-November 2010 Gunung Merapi eruption (Central Java, Indonesia) from the stratigraphy, volume and characteristics of its pyroclastic deposits  

NASA Astrophysics Data System (ADS)

The 2010 eruption of Merapi was the second most deadly in the historic record of this volcano, claiming over 380 lives. By relating the observations of this eruption with detailed examination of deposit distribution, stratigraphy and sedimentology, a reconstruction of the properties of the pyroclastic density currents (PDCs) is presented, including the valley controlled block-and-ash flows (BAFs) and widespread, energetic pyroclastic surges. The distribution, volume and mobility characteristics of all types of PDC during the eruption sequence show evidence for levels of intensity unseen since the large-scale 1872 and 1930 eruption phases, especially during the climactic events of October 26 and November 5. Many tephra falls interbedded with PDC units show that most dome-collapse events occurred along with and between explosive vulcanian eruptions. The 2010 eruption produced very long-runout BAFs, reaching 16.1 km in the Kali Gendol on November 5. This runout could be explained by its large-volume (20 million m3), around 10 times that of previous Merapi BAFs during the last 130 years. Major avulsion of these dense BAFs to form overbank deposits became more common through the eruptive sequence as the valley was progressively filled with successive PDC deposits. Spreading avulsed BAFs were a particular hazard downstream of ~ 10 km where the landscape is less dissected. Less clear, however, is why pyroclastic surges extended up to 10 km from the vent on November 5 and > 6.4 km on October 26. These expanded much farther from BAF margins (~ 2 km) than ever seen before at Merapi. In one location they were decoupled from valley-centered BAFs with high momentum, traveling initially laterally across steep valley systems, before draining downslope. At this site, on the western side of the upper Gendol at around 3 km from source, surge decoupling was apparently exacerbated by upstream collision and deflection of high-flux, hot and gas-rich BAFs against the cliffs of Gunung Kendil. The 1.4 km-long cliff face was impacted directly for the first time in 2010 events, and may have been responsible for the formation of larger than normal turbulent ash-rich clouds above BAFs. These results imply that future eruption events under the present summit and upper flow-path configuration are also highly likely to generate wide dispersal pyroclastic surges and extreme hazard, especially now that dense forest has been destroyed on the upper southern slopes of the volcano.

Cronin, Shane J.; Lube, Gert; Dayudi, Devi S.; Sumarti, Sri; Subrandiyo, S.; Surono

2013-07-01

370

Site characterization using a portable optically stimulated luminescence reader: delineating disrupted stratigraphy in Holocene eolian deposits on the Canadian Great Plains  

NASA Astrophysics Data System (ADS)

The use of portable optically stimulated luminescence (POSL) readers to elucidate on complex depositional sequences has been demonstrated in a number of recent studies. POSL readers are robust versions of the traditional lab-bound luminescence readers and they can be used in the field, allowing for rapid decisions to be made when collecting samples for dating. Furthermore, in contrast with lab-bound readers, POSL readers can perform measurements on bulk samples, negating the need to carry out time-intensive mineralogical separations. The POSL reader is equipped with both infra-red and blue light (OSL) stimulating sources such that signal separation during measurement can be carried out by selectively exciting feldspar using the IR source (IRSL) after which a quartz dominant signal is obtained from the same sample using post-IR blue OSL. The signals obtained are then plotted to give luminescence profiles that depict the variation of the luminescence signal with depth. Signal intensities depend on mineralogical concentrations, grain luminescence sensitivities, dose rates as well as on burial ages of the grains. Where all these variables, apart from the burial age, are held constant up the depositional sequence the luminescence profile serves as a proxy for the chronostratigraphy. As a contribution to a growing archive of studies that have employed POSL readers to unravel complex depositional sequences, this study uses a POSL system developed by the Scottish Universities Environmental Research Centre to characterize the stratigraphy at an archaeological site that lies next to an oilfield plant located on a Holocene fossil dune landscape in southern Alberta, Canada. Oilfield activity was initiated at the site several decades ago and it involved the laying of pipelines below ground which disturbed considerable archaeological deposits. Subsequent work led to the discovery of the archeological site which was previously occupied by ancestral indigenous peoples at various times during the mid to late Holocene. Ongoing maintenance of the original pipelines is now carefully monitored to maximize the protection of the site's archaeological resources, and a critical part of this process is the ability to distinguish between previously disturbed deposits from areas of the site that have intact stratigraphy. The POSL reader was incorporated in this study to address this aspect. As a preliminary test, excavations were made at selected sites and samples collected at 5 cm intervals from four separate profiles. These were then analyzed with the POSL reader using both IRSL and post IR blue OSL stimulation. A portable gamma ray spectrometer was used to determine concentrations of elements responsible for environmental radiation. Constructed luminescence profiles show that areas with disrupted stratigraphy are identifiable by the fluctuating signals, a result of the mixing of strata of varying age. Conversely, zones that have undisturbed stratigraphy display luminescence profiles that have stable signals or show an increase with depth. The luminescence profiling also allows the approximation of relative ages of the undisturbed strata. The approach used in this study has potential for a broad range of applications within the earth sciences.

Munyikwa, K.; Gilliland, K.; Gibson, T.; Plumb, E.

2012-12-01

371

A revised inoceramid biozonation for the Upper Cretaceous based on high-resolution carbon isotope stratigraphy in northwestern Hokkaido, Japan  

NASA Astrophysics Data System (ADS)

Hayakawa, T., Hirano, H. 2013. A revised inoceramid biozonation for the Upper Cretaceous based on high-resolution carbon isotope stratigraphy in northwestern Hokkaido, Japan. Acta Geologica Polonica, 63 (2), 239-263. Warszawa. Biostratigraphic correlations of inoceramid bivalves between the North Pacific and Euramerican provinces have been difficult because the inoceramid biostratigraphy of the Japanese strata has been based on endemic species of the northwest Pacific. In this study, carbon stable isotope fluctuations of terrestrial organic matter are assembled for the Upper Cretaceous Yezo Group in the Haboro and Obira areas, Hokkaido, Japan, in order to revise the chronology of the inoceramid biozonation in Japan. The carbon isotope curves are correlated with those of marine carbonates in English and German sections with the aid of age-diagnostic taxa. According to the correlations of the carbon isotope curves, 11 isotope events are recognised in the sections studied. As a result of these correlations, the chronology of the inoceramid biozones of the Northwest Pacific has been considerably revised. The revised inoceramid biozones suggest that the timing of the origination and extinction of the inoceramids in the North Pacific biotic province is different from the stage/substage boundaries defined by inoceramids, as used in Europe and North America.

Hayakawa, Tatsuya; Hirano, Hiromichi

2013-06-01

372

Seismic stratigraphy of the Tyrrhenian Sea (western Mediterranean Sea) based on ODP leg results: Consequences for the basin evolution  

SciTech Connect

A revision of the seismic stratigraphy of the Tyrrehenian Sea is based on detailed calibrations between a dense network of single-channel seismic reflection lines, about 2,000 km of recent multichannel seismic profiles, and the seven sites drilled within the Tyrrhenian in 1986 during the Ocean Drilling Program Leg 107. These correlations substantiate that the basin has been submitted to a succession of short-lived rifting episodes progressively shifting toward the southeast and leading to the local creation of discrete oceanic crust floored basins. Most of the Tyr-rhenian basins and margins have been created in a very short time (between 8 and 2 m.y. in age) and are much younger than previously anticipated. Rifting processes have been acting on a very heterogeneous continental basement (including several suture zones); drifting has created small oceanic subbasins also floored by a very heterogeneous magmatic basement (including serpentinized peridotites). The hypothesis of an asymmetric evolution facilitated by one or several crustal detachment fault systems and driven by geodynamic mechanisms of the bordering collision/subduction is considered.

Mascle, J.; Rehault, J.

1988-08-01

373

Tephra stratigraphy and geochemistry from three Icelandic lake cores: a new method for determining source volcano of tepra layers   

E-print Network

At present there is no consistent method for the identification of source volcanoes for a tephra layer found in a stratigraphy. This has led to several studies misidentifying source volcanoes. Geochemical analysis of the ...

Jagan, Anna

2010-01-01

374

Deciphering the Geochronological Framework of Serbian Loess Using Amino Acid Stratigraphy  

NASA Astrophysics Data System (ADS)

Serbian loess deposits preserve the most widespread, semi-continuous terrestrial records of glacial-interglacial climate variability in Europe. The sedimentary deposition, distribution, and thickness of loess in SE Europe are closely linked with major fluvial systems draining the continental interior. During glacial periods, under predominantly cold, semiarid climatic conditions, the extensive floodplain of the middle and lower Danube River was exposed to aeolian deflation, resulting in the accumulation of loess deposits up to 50 m thickness on adjacent fluvial terraces. The geomorphic setting of these loess formations, however, made them vulnerable to fluvial erosion and reworking, resulting in unconformities that may not be visually recognized in sedimentary sequences. Such unconformities, often of unknown duration and spatial extent, confound regional chronostratigraphic and paleoclimatic interpretations. Amino acid racemisation (AAR) geochronology, although primarily a relative dating method, offers an independent assessment of numerical age estimates when results are at or near their methodological limits and can assist in the chronostratigraphic evaluation of loess units beyond the applicable range of numerical dating methods. In this study we present the first comprehensive aminostratigraphic results measured on fossil gastropod shells of the genera Pupilla, Helicopsis, and Vallonia from the loess series at Stari Slankamen and Mosorin/Dukatar (Titel Plateau) in Vojvodina, Serbia, in order to verify the chronostratigraphic position of the upper stratigraphic units and to establish a reliable correlation between older loess-paleosol couplets. Given the interpreted stratigraphic continuity and the high sedimentation rates at Mosorin/Dukatar, we established this site as a chronostratigraphic reference for correlation with the long-studied loess profile Stari Slankamen, where at least two unconformities have led to ambiguous paleoclimatic and stratigraphic interpretation in previous studies. AAR analyses allow us to establish an independent chronostratigraphic framework for Serbian loess sequences correlated with marine oxygen-isotope stages 16-2. The results demonstrate the vast potential of amino acid stratigraphy to identify and constrain the extent, continuity, and duration of erosional discontinuities in long sedimentary sequences, such as those at Stari Slankamen. Ultimately, these results contribute to the development of a robust regional chronostratigraphic framework in support of paleoclimate reconstructions from high-resolution proxies, such as grain-size data, toward an improved understanding of the paleoenvironmental dynamics of SE Europe in an intra-hemispheric context.

Oches, E. A.; Machalett, B.; McCoy, W. D.; Markovic, S.

2010-12-01

375

GEOELECTRICAL STRATIGRAPHY AND ANALYSIS OF A HYDROCARBON IMPACTED AQUIFER  

EPA Science Inventory

A recently proposed geoelectrical model for hydrocarbon impacted sites predicts anomalously high conductivities coincident with aged contaminated zones. These high conductivities are attributed to an enhancement of mineral weathering resulting from byproducts of microbial redox p...

376

Bathymetry and seismic stratigraphy of East Greenland fjords and sounds  

NASA Astrophysics Data System (ADS)

Swath bathymetry and high-resolution penetration echo sounder (chirp) data from fjords and sounds between Kong Oscars Fjord (~72°30') and Bredefjord (~75°30'), East Greenland, reveal a variety of sedimentary processes related to glacial activity and mass wasting, as well as evidence of tectonic activity. The large-scale bathymetry of most fjords and sounds is characterized by sills that occasionally are shallower than 30 m, and basins reaching maximum water depths of more than 760 m. Multiple "steps", some more than 250 meters high and with gradients exceeding 60° (e.g. in Bredefjord) are most probably related to vertical movements along tectonic lineaments. The basin floors are typically smooth suggesting sedimentation predominantly from suspension settling. However, an approx. 100 m wide and 5 m deep channel in Kempefjord provides evidence of gravity-flow erosion sub-parallel to the fjord axis. Multiple sediment lobes along the fjord sides reflect repeated mass wasting. Relatively straight linear features oriented parallel to the fjord axes are interpreted to be glacial lineations that were formed beneath fast-flowing ice draining the Greenland Ice Sheet. They occur rarely on shallower plateaus and are often overlain by transverse ridges. In Youngsund, such ridges are typically 1-2 m high, 50 m wide and the distances between crests are most often approx. 100 m. The ridges are most probably 'retreat moraines' that were deposited during minor halts and/or re-advances during the last deglaciation. More curvilinear and randomly oriented furrows with raised rims are most probably iceberg ploughmarks that were formed from grounded icebergs calving off the Greenland Ice Sheet during the last deglaciation (e.g. in Rudis Bugt). Elongated to round, randomly distributed depressions of up to >10 m depth and >200 m width occur, e.g. in the inner parts of Tyrolerfjord. They are often filled with acoustically stratified sediments and we assume that they might have resulted from post-glacial tectonic activity. Up to 180 ms two-way travel time thick acoustically stratified sequences dominate the fjord-fill and sound-fill stratigraphies. These deposits are suggested to reflect repeatedly changing physical conditions in a glacimarine environment where deposition occurred from suspension fall-out, ice rafting from icebergs and sea ice, as well as smaller-scale mass wasting. An acoustically transparent drape overlies these deposits rarely (e.g. in Rudis Bugt). Multiple acoustically transparent bodies with irregular geometries intercalated within the stratified deposits are suggested to reflect repeated larger-scale mass wasting, either from slope failures along fjord sides or related to glacier advances (e.g. in Nordfjord). Occasional distortions and blanking of reflections (e.g. in Nordfjord and Kong Oscar Fjord) might be related to relatively recent tectonic activity and fluid flow/gas expansion.

Forwick, Matthias; Sverre Laberg, Jan; Husum, Katrine; Olsen, Ingrid L.

2014-05-01

377

Hydrological and sedimentological variability of the peri-fluvial wetlands of the middle Loire river (France)  

NASA Astrophysics Data System (ADS)

With a catchment basin of 112,120 km^2 and a length of 1012 km, the Loire River is one of the most important fluvial hydrosystems in France. Notwithstanding numerous modifications (dikes, dams, nuclear power plants, gravel extractions), the Loire River hydrology has been saved from a total regularisation. Therefore, the spatial diversity of fluvial landforms creates a patchwork of wetlands: ox-bow lakes, dewatered channels... As one aim of this work was to determine the hydrological and sedimentological processes in the various wetlands, in a context of spatial variability of the fluvial landforms, we used a pluridisciplinarity approach: geomorphology, hydrology, geochemistry. The present study has targeted the functioning between the various hydro-geomorphologic units of the floodplain (main and secondary active channels, abandoned branches and the riverbank [alluvial] and perched aquifers), with regard to the spatial heterogeneity of the different fluxes and the temporal variations of bottom water level, full-bank stage and overflow discharge. In the upper part of the study area, mobile meanders prevail. The meanders migration results in oxbow lakes and the connection between the lakes and the other water reservoirs (e.g. river- and groundwaters) induce a strong lateral variability and a time delayed water input by the river as evidenced by the different geochemical and isotopic signatures. Downstream, the Loire River develops a multiple-channels pattern, of which numerous are abandoned. They are often dewatered along the year, only reconnected to the main channel during the periods of overflow discharges and the influence of the Loire riverwater is progressively substituted by the input of groundwaters (alluvial and perched aquifers). It appears that the submersion duration and the type of connection between the wetlands and the various reservoirs (inlet or outlet connection with the river, connection with the aquifers.) strongly influence the sedimentation rate and granulometric features.

Gautier, E.; Kunesch, S.; Negrel, P.; Petelet-Giraud, E.

2003-04-01

378

Sedimentology and paleogeography of the Natih carbonate platform in the Oman mountains  

SciTech Connect

Field study of the Natih Formation in the Jebel Akhdar and the Oman foothills allows us to establish a new stratigraphical and sedimentological model of this important hydrocarbon reservoir unit. Thanks to the study of rudists and the discovery of ammonites, a new precisions can be given to the chronostratigraphy of the Natih Formation. It was especially demonstrated by the presence of Hippuritids (rudists) that the top of the Natih Formation matches the Cenomanian/Turonian boundary and corresponds to either rudist-rich layers or hard grounds and condensed levels. The stratigraphical correlations between several outcrop section allow one to establish a conceptual sequence stratigraphic model which can be compared to the subsurface by using the Natih subdivisions [open quotes]A to G.[close quotes] The recognition of sequence boundaries, maximum flooding surfaces, and system tracts might help to understand the seismo-stratigraphic expression of the Natih interval in the subsurface. Furthermore, this sequence stratigraphic model clearly illustrates the interfingering of the carbonate reservoir intervals and the organic-rich units (Fitri Mb) at the top of the Natih Formation. We also have identified a clear zonation from deeper marine to shallow-marine carbonate deposits, the most significant of which are the rudistid facies. They form banks, thickets, and biostroms and do not constitute anomalous build ups such as bioherms. Good leaching potentials generally are related to these rudistid facies, especially when they are very rich in skeletal aragonite from the Caprinids shells. Significant primary porosity may be related also to the Hippuritid skeletal cavities at the top of the Natih. Reservoir potentials can be enhanced if these Caprinid-rich intervals are related to exposure surfaces such as the top Natih E and the top Natih A.

Philip, J.M. (Univ. Aix-Marseille I, Marseille (France)); Borgomano, J.R.; Al Maskiry, S. (Petroleum Development Oman, Muscat (Oman))

1993-09-01

379

Sedimentologic succession of uplifted coral community, Urvina Bay, Isabela Island, Galapagos Archipelago, Ecuador  

SciTech Connect

In March 1954, along the west-central coast of Isabela Island, an upward movement of magma suddenly raised Urvina Bay over 6 m and exposed several square kilometers of carbonate deposits covering a young aa lava flow (around 1000 years old). Results from 6 transect lines across the uplift, 30 cores, and 10 trenches describe the sedimentologic and ecologic transition from barren basalt to diverse carbonate sediments with small coral reefs. Along horizontal transects spanning from 0 to 7 m paleowater depth, there is a seaward progression from beaches, mangroves, and basalt to thick deposits (> 1.6 m) of carbonate sands and small coral reefs. Variation in water depth, degree of wave exposure, and irregularity of the aa lava topography provided many microhabitats where coral, calcareous algae, and mollusks settled and grew. Eight hermatypic coral species are found throughout the shelf, and three species (i.e., Pavona clavus, Pocillopora damicornis, and Porites lobata) produced five small, isolated, monospecific, coral-reef frameworks. The vertical section seen in cores and trenches shows that calcium carbonate increased upward, whereas volcanic sediments decreased; however, episodic layers occur with high concentrations of basaltic sands. In vertical samples from the central portion of the shelf, the coral population changed from small, isolated colonies of Psammocora (Plesioseris) superficalis near the basalt basement to large reef-forming colonies of Pocillopora damicornis farther upsection. Reefs of the Galapagos Islands are small and less diverse than most Pacific reefs. Nonetheless, understanding their temporal successional development should throw light on the origin and history of larger oceanic reefs in the Pacific.

Colgan, M.W.; Hollander, D.

1987-05-01

380

The Ardross reservoir gridblock analogue: Sedimentology, statistical representivity, and flow upscaling  

SciTech Connect

We have used a reservoir gridblock-sized outcrop (10m by 100m) of fluvio-deltaic sandstones to evaluate the importance of internal heterogeneity for a hypothetical waterflood displacement process. Using a dataset based on probe permeameter measurements taken from two vertical transacts representing {open_quotes}wells{close_quotes} (5cm sampling) and one {open_quotes}core{close_quotes} sample (exhaustive 1mm-spaced sampling), we evaluate the permeability variability at different lengthscales, the correlation characteristics (structure of the variogram, function), and larger-scale trends. We then relate these statistical measures to the sedimentology. We show how the sediment architecture influences the effective tensor permeability at the lamina and bed scale, and then calculate the effective relative permeability functions for a waterflood. We compare the degree of oil recovery from the formation: (a) using averaged borehole data and no geological structure, and (b) modelling the sediment architecture of the interwell volume using mixed stochastic/deterministic methods. We find that the sediment architecture has an important effect on flow performance, mainly due to bedscale capillary trapping and a consequent reduction in the effective oil mobility. The predicted oil recovery differs by 18% when these small-scale effects are included in the model. Traditional reservoir engineering methods, using averages permeability values, only prove acceptable in high-permeability and low-heterogeneity zones. The main outstanding challenge, represented by this illustration of sub-gridblock scale heterogeneity, is how to capture the relevant geological structure along with the inherent geo-statistical variability. An approach to this problem is proposed.

Ringrose, P.; Pickup, G.; Jensen, J. [Heriot-Watt Univ., Edinburgh (United Kingdom)] [and others

1997-08-01

381

Morphology and sedimentology of a central Brazos River point bar, Boxley Bend, Brazos County, Texas  

SciTech Connect

A reconnaissance of Brazos River point bars reveals great variety in their morphology and sedimentology, owing to the complex interaction of climate, local hydrography, and local sediment sources. This paper presents the first in a series of studies of point bars of the Brazos River and concentrates on the Boxley Bend point bar near Snook, Texas. The summer morphology of the point bar is complex, consisting of an upper and lower tier separated by a scarp but connected by a central ramp. The surfaces of the lower tier and ramp display numerous large gravel bars and shallow scour pools as well as low-amplitude sand waves, ripples, and current lineations. In cross section, the lower tier and ramp are characterized by (1) trough cross-bedded, medium to fine sand produced by megaripple migration during floods; (2) massive gravel beds, the product of formation and migration of gravel bars during floods; and (3) fine rippled sand and clay drapes formed during falling flood. The surface of the upper tier displays ripple-laminated eolian sand and deflation deposits of mud clasts. In cross section, the upper tier is characterized by thick beds of horizontally stratified fine sand. During the winter, the entire surface of the point bar is covered by large (2 m high) transverse bars separated by deep scour troughs. Transverse bars migrate into the troughs to produce a sequence of fine sand with backflow ripple cross-stratification overlain by thick beds of tabular cross-bedded medium sand. The transverse bars appear to be transitory features with little net effect on sedimentation, because they are removed from the surface of the point bar by summertime.

Connolly, W.M.; Mazzullo, J.

1986-09-01

382

Sedimentology, diagenesis, and oil habitat of Lower Cretaceous Qamchuqa Group, Northern Iraq  

SciTech Connect

The Zagros basin (Iraq) constitutes a rich petroleum province. The Lower Cretaceous Qamchuqa Group comprises on of its major reservoirs. Data from about 30 wells, drilled in a limited sector corresponding to a northwest-southeast anticlinal structure situated in the Kirkuk region, permit analysis of serveral sedimentological and diagenetic events that led to the formation of this reservoir. Facies changes took place and divided the structure into three parts: the northwestern part in which neritic facies dominate, the central part in which basinal influence is considerable, and the southeastern part that shows basinal mudstone type facies. The Lower Cretaceous carbonate platform in the northwestern part of the study area displays good primary porosity. During the course of burial, high secondary porosity related to dolomitization appeared. However, a major part of the porosity was produced when the reservoir was fractured during the Priabonian after the collision between the Arabian and Eurasian plates. Lopatin`s method suggests that organic matter maturation started during the Turonian (around 90 MA), whereas most of the maturation developed during the Miocene due to the rapid accumulation of foreland basin sediments containing evaporite facies (lower Fars Formation) followed by the accumulation of thick upper molasse-type sediments from the erosion of the Zagros Mountains. The accumulation of sediments enhanced the total tectonic subsidence. During this period, the relatively brief time spent by the source rock in a given temperature interval was compensated for by a rapid rise in temperature. This late thermal maturation period controlled most of the transformation of the organic matter into hydrocarbons.

Al Shdidi, S.; Thomas, G.; Delfaud, J. [Avenue de l`Universite, Pau (France)

1995-05-01

383

Sedimentological, biogeochemical and mineralogical facies of Northern and Central Western Adriatic Sea  

NASA Astrophysics Data System (ADS)

The aim of this work was to identify sedimentary facies, i.e. facies having similar biogeochemical, mineralogical and sedimentological properties, in present and recent fine sediments of the Northern and Central Adriatic Sea with their spatial and temporal variations. Further aims were to identify the transportation, dispersion and sedimentation processes and provenance areas of sediments belonging to the facies. A Q-mode factor analysis of mineralogical, granulometric, geochemical (major and trace elements) and biochemical (organic carbon and total nitrogen) properties of surficial and sub-surficial sediments sampled in the PRISMA 1 Project has been used to identify the sedimentary facies. On the whole, four facies were identified: 1) Padanic Facies, made up of fine siliciclastic sediments which reach the Adriatic Sea mainly from the Po River and are distributed by the Adriatic hydrodynamic in a parallel belt off the Italian coast. Southward, this facies gradually mixes with sediments from the Apennine rivers and with biogenic autochthonous particulate; 2) Dolomitic Facies, made up of dolomitic sediments coming from the eastern Alps. This facies is predominant north of the Po River outfalls and it mixes with Padanic Facies sediments in front of the Po River delta; 3) Mn-carbonate Facies, made up of very fine sediments, rich in coccolithophores and secondary Mn-oxy-hydroxides resulting from the reworking of surficial fine sediments in shallow areas and subsequent deposition in deeper areas; 4) Residual Facies, made up of coarse siliciclastic sediments and heavy minerals resulting from the action of waves and coastal currents; this facies is present mainly in inshore areas. The zoning of the facies, resulting from this study, will make possible the identification, through further investigation, on a greater scale, of more accurate facies borders and the recognition of sub-facies, resulting from secondary or weaker biogeochemical processes.

Spagnoli, Federico; Dinelli, Enrico; Giordano, Patrizia; Marcaccio, Marco; Zaffagnini, Fabio; Frascari, Franca

2014-11-01

384

Sedimentological control on Mn, and other trace elements, in groundwater of the Bengal delta.  

PubMed

To reveal what controls the concentration and distribution of possibly hazardous (Mn, U, Se, Cd, Bi, Pb) and nonhazardous (Fe, V, Mo, PO(4)) trace elements in groundwater of the Bengal delta, we mapped their concentrations in shallow groundwater (<60 mbgl) across 102 km(2) of West Bengal. Only Mn is a potential threat to health, with 55% of well water exceeding 0.3 mg/L, the current Indian limit for drinking water in the absence of an alternate source, and 75% exceeding the desirable limit of 0.1 mg/L. Concentrations of V are <3 ?g/L. Concentrations of U, Se, Pb, Ni, Bi, and Cd, are below WHO guideline values. The distributions of Fe, Mn, As, V, Mo, U, PO(4), and ?(18)O in groundwater reflect subsurface sedimentology and sources of water. Areas of less negative ?(18)O reveal recharge by sources of evaporated water. Concentrations of Fe, As, Mo, and PO(4) are high in palaeo-channel groundwaters and low in palaeo-interfluvial groundwaters. Concentrations of U, V, and Mn, are low in palaeo-channel groundwaters and high in palaeo-interfluvial groundwaters. Concentrations of Fe and Mn are highest (18 and 6 mg/L respectively) at dual reduction-fronts that form strip interfaces at depth around the edges of palaeo-interfluvial aquifers. The fronts form as focused recharge carries dissolved organic carbon into the aquifer margins, which comprise brown, iron-oxide bearing, sand. At the Mn-reduction front, concentrations of V and Mo reach peak concentrations of 3 ?g/L. At the Fe-reduction front, concentrations of PO(4) and As reach concentrations 3 mg/L and 150 ?g/L respectively. Many groundwaters contain >10 mg/L of Cl, showing that they are contaminated by Cl of anthropogenic origin and that organic matter from in situ sanitation may contribute to driving reduction. PMID:22148466

McArthur, J M; Sikdar, P K; Nath, B; Grassineau, N; Marshall, J D; Banerjee, D M

2012-01-17

385

Sedimentology of high-stage flood deposits of the Tagus River, Central Spain  

NASA Astrophysics Data System (ADS)

This paper details the sedimentology of high-stage flood deposits, with the definition of sedimentary environments and their characteristic sequences, along two bedrock reaches of the Tagus River (Central Spain). High-stage flood deposits accumulated in bedrock canyons include slackwater flood deposits (SWD) and other types of deposits located at flow separation zones and associated with slow-moving flow (<1 m s -1). These flood deposits are common indirect indicators of flood stages used in palaeoflood studies for estimating the discharges associated with Quaternary floods. Depositional environments of flood deposits include (1) channel widening, (2) canyon expansion, (3) bedrock obstacles, and (4) backflooded areas along tributary streams. These flood deposits can be found associated with other non-fluvial environments, namely aeolian reworked and slope washflow facies. Channel widening, due to flood stage variations, comprises internal and external zones of the channel margins, and their characteristic sequences contain similar facies to those of alluvial floodplains. Canyon expansion environments favour vertical accretion of slackwater units and the development of flood deposit benches, which contain four sequences related to bench elevation and distance from the channel's main thread of flow. At the lee side of bedrock obstacles, characteristic sedimentary sequences are dominated by reverse flow structures (e.g. climbing ripples migrating upstream) due to eddies with a high sand concentration. Flood deposits located within tributary mouths contain typical sequences of reworked floodplain deposits. Backflooding of tributaries during flood stages produces deposition from suspension of sand, silt and clay within three sequences characterised by non-structure or parallel lamination and intense bioturbation. A better understanding of the flood deposit sequences may contribute to the characterisation of flood magnitudes and flood hydraulics and can also be applied to some ancient depositional environments.

Benito, Gerardo; Sánchez-Moya, Yolanda; Sopeña, Alfonso

2003-03-01

386

Geomorphology, facies architecture, and high-resolution, non-marine sequence stratigraphy in avulsion deposits, Cumberland Marshes, Saskatchewan  

Microsoft Academic Search

This paper demonstrates field relationships between landforms, facies, and high-resolution sequences in avulsion deposits. It defines the building blocks of a prograding avulsion sequence from a high-resolution sequence stratigraphy perspective, proposes concepts in non-marine sequence stratigraphy and flood basin evolution, and defines the continental equivalent to a parasequence.The geomorphic features investigated include a distributary channel and its levee, the Stage

K. M. Farrell

2001-01-01

387

Salt tectonism and seismic stratigraphy of the Upper Jurassic in the Destin Dome Region, northeastern Gulf of Mexico  

E-print Network

SALT TECI'ONISM AND SEISMIC STRATIGRAPHY OF THE UPPER JURASSIC IN THE DESTIN DOME REGION, NORTHEASTERN GULF OF MEXICO A Thesis by GRANT MACRAE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 1990 Major Subject: Oceanography SALT TECI'ONISM AND SEISMIC STRATIGRAPHY OF THE UPPER JURASSIC IN THE DESTIN DOME REGION, NORTHEASTERN GULF OF MEXICO A Thesis by GRANT MACRAE Approved...

MacRae, Grant

2012-06-07

388

Neogene carbonate exploration play concepts for Northern New Guinea: New iteration from field work and seismic stratigraphy along the Northern New Guinea Fault Zone  

SciTech Connect

Recent field reconnaissance, petrography, nanno and foraminifera age determinations, and seismic stratigraphy of the Sepik and Piore subbasins of northern New Guinea reveal the existence of an extensive, tectonically unstable, Miocene-Pliocene carbonate shelf system. These findings represent the first recorded evidence of northern Papuan limestones coeval in age to those of the hydrocarbon productive Salawati Basin of Irian Jaya. Moreover, these observations also demonstrate the significance of episodic activities of the northern New Guinea fault zone upon the changes in carbonate sedimentation and diagenesis. During the Neogene, algal biosparites to foraminiferal biomicrites defined the clean portion of a mixed clastic-carbonate shelf system of the northern New Guinea basin, which began at the central New Guinea cordillera and deepened northward. This shelf was interrupted by coral-coralline algal boundstone fringing- to patch-reef buildups with associated skeletal grainstones. Clean carbonates were spatially and temporally restricted to basement blocks, which episodically underwent uplift while terrigenous dilutes carbonates were more common in adjacently subsiding basement block bathymetric lows. These tectonic expressions were caused by the spatially transient nature of constraining bends of the evolving north New Guinea faults. As shown by seismic stratigraphy, by the late Miocene to the early Pliocene the uplift of the Bewani-Torricelli Mountains sagittally divided the shelf of the northern New Guinea basin into the Ramu-Sepik and the Piore basins. Continued regional sinistral transpression between the Pacific and the New Guinea leading edge of the Indo-Australian plates led to the reverse tilting of the Piore basin, the shallowing of the former distal shelf with concomitant extensive biolithite development (e.g., on subsiding volcanic islands) eventual uplifting of the Oenake Range, and en echelon faulting of the Bewani-Torricelli Mountains.

Pigott, J.D.; Geiger, C. (Univ. of Oklahoma, Norman, OK (United States))

1994-07-01

389

Using NIR Photography to Document Snow Stratigraphy Quickly: Lessons from Three Field Campaigns  

NASA Astrophysics Data System (ADS)

We began using near-infrared (NIR) photography as a quick way to document snow stratigraphy in 2006 as part a snow validation campaign in Barrow, Alaska. Seventeen snow pits (30 to 80 cm deep) were photographed using a Sony DSC-P200 Cybershot 7.2-megapixel digital camera supported on a mini-tripod and equipped with a NIR filter (850 nm). Standard layer measurements of thickness, density, grain size, hardness, and grain type were also made in each pit. During the 2007 SnowSTAR traverse across Alaska and Canada, 43 snow pits were photographed and measured in the same fashion. During the CLPX-Alaska campaign of 2008, three trenches each about 10 m long were photographed in their entirety as well as documented in a traditional manner, this time using a Fuji S9100 9 mega-pixel digital camera with an 850 nm filter. For the trenches, the camera was supported on a sliding rail system. NIR photographs were processed using Image-J software and a simple algorithm that enhanced contrast based on grain size. Our goal is to develop a method of documenting stratigraphy that is faster than recording the results in a field book. For a 50 cm deep pit prior methods of recording stratigraphy would have required about 30 minutes. We succeeded in reducing the average time to acquire a pit photograph to less than 15 minutes. However, pit face preparation time increased by about 15 minutes because of the need to produce a smooth, divot-free snow surface. Required protocols to compute grain size from the photos added a further 20 minutes or more if used, so frequently these were omitted. While at present there is no real net reduction in the time to record stratigraphy using NIR photography vs. older methods, the result is superior in all ways to our best previous efforts to "map" the stratigraphy though hand-recorded data. A combination of older traditional methods and NIR photography is strongly recommended as the best method to document the snow stratigraphy.

Sturm, M.; Tape, K.; Liston, G. E.; Rutter, N.

2008-12-01

390

The Late Holocene Stratigraphy of an Inlet-Dominated Barrier Island, Pea Island, North Carolina.  

NASA Astrophysics Data System (ADS)

Sedimentological, foraminiferal, geochemical, and geophysical data sets as well as aerial photographs have been used to investigate the natural processes (inlet dynamics, ocean/estuarine washover, and sea-level change) responsible for the late Holocene units preserved in the barrier island subsurface at Pea Island National Wildlife Refuge. Historic nautical charts indicate that three inlets characterized Pea Island between early European exploration (1590) and the late 19th century; aerial photographs show New Inlet open in 1932 and 1940. Vibracores (up to 5.5 m) collected along three transects across Pea Island extend our knowledge of the geological evolution of this region to pre-historic times. The section in the longest core (PI01S6) consists of four fining-upwards depositional sequences. The basal unit of each sequence is a bedded, medium to fine, clean quartz sand with increasing concentrations of organic matter (3-4 % detrital and 5-7 % in situ Spartina alterniflora roots) or irregular mud clasts (2-5 cm) to spherical mud balls (1-2 cm) up core. The clean sand units have so far proven to be barren of foraminifera except for a shelly unit at ca. 220 cm below MSL. The foraminiferal assemblage in this unit is of open shelf character (Elphidium excavatum, Hanzawaia strattoni, and Buccella inusitata). A 14C age on a disarticulated Chione cancellata valve from this unit is cal. 930+/-60 BP. The sand grades into a gray, tight mud in the first two sequences and into an inter-laminated mud and in situ peat in the third sequence. The peat contains leaf fragments and rhizomes of the marsh plants Juncus roemarianus, Spartina cynosuroides, and/or Phragmites spp. The peat and muddy sand units contain marsh foraminifera (Trochammina spp., Miliammina fusca, Arenoparrella mexicana), which are also found in modern marsh deposits. A peat sample from the third fining upward sequence (the only one to grade into a true peat) has a 14C age of cal. 395+/-35 BP, cal. 295+/-35 BP, or cal 180+/-40 BP. The four fining-upwards sequences have sharp erosional basal contacts. These deposits appear to reflect back-barrier processes including sequential deposition of flood-tide delta sands and/or sound sands adjacent to marshes. The shelly sands, containing open shelf foraminiferal assemblages, represent oceanic overwash, inlet deposits, or open embayment sands deposited behind a laterally extensive breach in the barrier island. The sequences are capped by the deposits of modern environments that include algal flats, tidal creeks, high and low marshes, back-barrier berms, overwash fans, and aeolian dunes. Several of the modern environments became covered with marsh vegetation after the construction of barrier dune ridges in the late 1930?s.

Smith, C. G.; Ames, D.; Corbett, D. R.; Culver, S.; Mallinson, D.; Riggs, S. R.; Vance, D.

2002-12-01

391

Sedimentology of the Neoproterozoic (c. 580 Ma) Squantum 'Tillite', Boston Basin, USA: Mass flow deposition in a deep-water arc basin lacking direct glacial influence  

NASA Astrophysics Data System (ADS)

The Squantum 'Tillite' (c. 593-570 Ma) consists of thick (up to 215 m) massive and crudely-stratified diamictites conformably interbedded with subaqueously-deposited conglomerates and sandstones within a thick (~ 7 km) Boston Basin fill which is dominated by argillite turbidites. The Squantum Tillite was first interpreted as being glacigenic in origin in 1914 because of the presence of diamictites; argillites were interpreted as glaciolacustrine 'varves' with rare ice-rafted debris, and conglomerates as glaciofluvial outwash. More recently these have been shown to be the product of deep marine mass flow processes with no glacial influence, yet because of its age equivalence with the deep marine, glacially-influenced Gaskiers Formation, the Squantum Tillite is still seen by some as supporting evidence for a widespread 'Snowball Earth' event at c. 580 Ma. New sedimentological work confirms that conglomerate and sandstone facies are deep marine sediment gravity flows genetically related to massive (homogeneous) and crudely-stratified (heterogeneous) diamictites produced subaqueously by downslope mixing of gravel and cobbles with muddy facies. Rare horizons of 'ice rafted debris' in thin-bedded and laminated turbidite facies interbedded with thick debrites show a weak but positive correlation of lamina thickness with grain size, suggesting these facies are non-glacial co-genetic 'debrite-turbidite' couplets. A significant volcanic influence on sedimentation is identified from reworked lapilli tuff beds and reworked ash in turbidites. The depositional setting of the Squantum 'Tillite' appears to be that of a submarine slope/fan setting in an open marine volcanic arc basin receiving large volumes of poorly-sorted sediment on the mid-latitude active margin of Gondwana. No direct glacial influence is apparent.

Carto, Shannon L.; Eyles, Nick

2012-08-01

392

Postglacial eruptive history of Laguna del Maule volcanic field in Chile, from fallout stratigraphy in Argentina  

NASA Astrophysics Data System (ADS)

The Laguna del Maule (LdM) volcanic field, which surrounds the 54-km2 lake of that name, covers ~500 km2 of rugged glaciated terrain with Quaternary lavas and tuffs that extend for 40 km westward from the Argentine frontier and 30 km N-S from the Rio Campanario to Laguna Fea in the Southern Volcanic Zone of Chile. Geologic mapping (Hildreth et al., 2010) shows that at least 130 separate vents are part of the LdM field, from which >350 km3 of products have erupted since 1.5 Ma. These include a ring of 36 postglacial rhyolite and rhyodacite coulees and domes that erupted from 24 separate vents and encircle the lake, suggesting a continued large magma reservoir. Because the units are young, glassy, and do not overlap, only a few ages had been determined and the sequence of most of the postglacial eruptions had not previously been established. However, most of these postglacial silicic eruptions were accompanied by explosive eruptions of pumice and ash. Recent investigations downwind in Argentina are combining stratigraphy, grain-size analysis, chemistry, and radiocarbon dating to correlate the tephra with eruptive units mapped in Chile, assess fallout distribution, and establish a time-stratigraphic framework for the postglacial eruptions at Laguna del Maule. Two austral summer field seasons with a tri-country collaboration among the geological surveys of the U.S., Chile, and Argentina, have now established that a wide area east of the volcanic field was blanketed by at least 3 large explosive eruptions from LdM sources, and by at least 3 more modest, but still significant, eruptions. In addition, an ignimbrite from the LdM Barrancas vent complex on the border in the SE corner of the lake traveled at least 15 km from source and now makes up a pyroclastic mesa that is at least 40 m thick. This ignimbrite (72-75% SiO2) preceded a series of fall deposits that are correlated with eruption of several lava flows that built the Barrancas complex. Recent 14C dates suggest that most of the preserved LdM fallout eruptions were between 7 ka and 2 ka. However, the oldest and perhaps largest fall unit yet recognized is correlated with the Los Espejos rhyolite lava flow that dammed the lake and yields a 40Ar/39Ar age of 23 ka. Pumice clasts as large as 8.5 cm and lithics to 4 cm were measured 32 km ENE of source. It is the only high-silica rhyolite (75.5-76% SiO2) fall layer yet found, correlates chemically with the Los Espejos rhyolite lava flow, and includes distinctive olivine-bearing lithics that are correlated with mafic lavas which underlie the Espejos vent. Extremely frothy pumice found near the vent is also consistent with the bubble-wall shards and reticulite pumice distinctive of the correlative fall deposit. Another large rhyolite fall deposit (74.5% SiO2), 4 m thick 22 km E of source, has pumice clasts to 9.5 cm and includes ubiquitous coherent clasts of fine, dense soil that suggests it erupted through wet ground; 14C dates (uncalibrated) yield ages ~7 ka. Stratigraphic details suggest that pulses of fallout were accompanied by small pyroclastic flows. Ongoing field and lab work continues to build the LdM postglacial eruptive story. The numerous postglacial explosive eruptions from the LdM field are of significant concern because of ongoing 33 cm/year uplift along the western lakeshore, as measured by InSAR and verified by GPS.

Fierstein, J.; Sruoga, P.; Amigo, A.; Elissondo, M.; Rosas, M.

2012-12-01

393

Stratigraphy and erosional landforms of layered deposits in Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

Satellite imagery is used to identify stratigraphy and erosional landforms of 13 layered deposits in the Valles Marineris region of Mars (occurring, specifically, in Gangis, Juventae, Hebes, Ophir-Candor, Melas, and Capri-Eos Chasmata), based on albedo and erosional styles. Results of stratigraphic correlations show that the stratigraphy of layered deposits in the Hebes, Juventae, and Gangis Chasmata are not well correlated, indicating that at least these chasmata had isolated depositional environments resulting in different stratigraphic sequences. On the other hand, the layered deposits in Ophir-Candor and Melas Chasmata appear to have been connected in each chasma. Some of the layered deposits display complexities which indicate changes in space and time in the dominant source materials.

Komatsu, G.; Geissler, P. E.; Strom, R. G.; Singer, R. B.

1993-06-01

394

Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis  

SciTech Connect

This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

Suzette Payne

2007-08-01

395

Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis  

SciTech Connect

This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

Suzette Payne

2006-04-01

396

40Ar/(39)Ar geochronology and paleomagnetic stratigraphy of the Lukeino and lower Chemeron Formations at Tabarin and Kapcheberek, Tugen Hills, Kenya.  

PubMed

(40)Ar/(39)Ar single-crystal laser-fusion dating, K-Ar dating, and paleomagnetic reversal stratigraphy have been used to determine the chronostratigraphy of the Kabarnet Trachyte, Lukeino Formation, Kaparaina Basalt Formation, and Chemeron Formation at the sites of Kapcheberek (BPRP#77) and Tabarin (BPRP#77) in the Tugen Hills, Kenya. The succession ranges in age from 6.56-3.8 Ma. The upper Lukeino Formation at Kapcherberek, including the fauna from the site BPRP#76, was deposited during chron C3r and can be constrained to the interval 5.88-5.72 Ma. The Chemeron Formation at Tabarin includes at the base an ignimbrite and associated basal air-fall tuff with a combined age of 5.31+/-0.03 Ma. Sedimentary and volcaniclastic rocks of the Chemeron Formation which unconformably overlie the ignimbrite record chrons C3n.2n through C2Ar. The combined(40)Ar/(39)Ar and paleomagnetic data constrain the age of this sequence to 4.63-3.837 Ma. The age of the Tabarin mandible fragment (KNM-TH 13150) and associated fauna at site BPRP#77 in the Chemeron Formation is 4.48-4.41 Ma, marginally older than similar early hominids from Aramis, Ethiopia. Basin subsidence appears to be defining an overall accumulation rate of about 17 cm/ka over the 2.7 Ma represented at Tabarin and Kapcheberek, despite episodes of rapid accumulation and hiatuses. PMID:11795971

Deino, Alan L; Tauxe, Lisa; Monaghan, Marc; Hill, Andrew

2002-01-01

397

Loess–paleosol stratigraphy of Dukso area, Namyangju City, Korea (South)  

Microsoft Academic Search

As Korea lies between China, with a drier climate, and the wetter Japanese Islands, the Korean loess–paleosol stratigraphy constitutes an important record of variations in the East Asian monsoon climate. The loess–paleosol sequence consists of three loess layers (L1LL1, L1LL2, and L2) and three paleosols (L1SS1, S1, and S2) in the study area. L1LL1 accumulated near the surface, and is

Kang-Min Yu; Jae-Bong Shin; Toshiro Naruse

2008-01-01

398

Correlation of stratigraphy with revegetation conditions at the Gibbons Creek Lignite Mine, Grimes County, Texas  

E-print Network

and hydrometer analyses. The geochemical parameters ? acidity, potential acidity, salinity, and trace metal concentration in the soil ? are compared with the Railroad Commission of Texas regulation values. The final step, correlating the environments... . Stratigraphy, DETERMINATION OF THE ENVIRONMENTS OF DEPOSITION . . 13] 13, ' 15/ 20 Geophysical Logs 20 Caliper Logs . Gamma-Ray Logs Density Logs . Resistivity Logs 20 22' 22, 25' Hydrometer Analyses Core Description Environments of Deposition...

Parisot, Laurence D.

2012-06-07

399

Lower Cretaceous turbiditic sediments from the Rif chain (Northern Marocco) — palynology, stratigraphy and palaeogeographic setting  

Microsoft Academic Search

Zusammenfassung  Von den afrikanischen und Alboran-Kontinentalrändern der westlichen Tethys (Externe Domäne und Flyschdecken im Rif, Nordmarokko) werden terrigene turbiditische Tiefseesedimente von Unterkreidealter beschrieben (Palynologie, Stratigraphie, Sedimentologie und paläogeographischer Rahmen).Während der Unterkreide finden sich terrigene turbiditische Tiefseeablagerungen in zwei verschiedenen paläogeographischen Räumen des Südteils der westlichen Tethys:? \\u000aIm Nordteil der Externen Domäne (Ketama-Einheit des Rif) werden Wechsellagerungen von Areniten und Peliten als

Alfred A. Gübeli; Peter A. Hochuli; Walter Wildi

1984-01-01

400

Image analysis for measuring stratigraphy in sand-gravel laboratory experiments  

NASA Astrophysics Data System (ADS)

Measurements of spatial and temporal changes in the grain size distribution are crucial to improving the modelling of sediment transport and associated grain size-selective processes. We present three complementary techniques to determine such variations in the grain size distribution in sand-gravel laboratory experiments, as well as the resulting stratigraphy: (1) particle colouring, (2) removal of sediment layers, and (3) image analysis. The resulting stratigraphy measurement method has been evaluated in two sets of experiments. In both sets three grain size fractions within the range of coarse sand to fine gravel were painted in different colours. Sediment layers are removed using a wet vacuum cleaner. Subsequently areal images are taken of the surface of each layer. The areal fraction content, i.e. the relative presence of each size fraction over the bed surface, is determined using a colour segmentation algorithm which provides the areal fraction content of a specific colour (i.e., grain size) covering the bed surface. Particle colouring is not only beneficial to this type of image analysis but also