Age and microfacies of oceanic Upper Triassic radiolarite components from the Middle Jurassic ophiolitic mélange in the Zlatibor Mountains (Inner Dinarides, Serbia) and their provenance

NASA Astrophysics Data System (ADS)

Gawlick, Hans-Jürgen; Djerić, Nevenka; Missoni, Sigrid; Bragin, Nikita Yu.; Lein, Richard; Sudar, Milan; Jovanović, Divna

2017-08-01

Oceanic radiolarite components from the Middle Jurassic ophiolitic mélange between Trnava and Rožanstvo in the Zlatibor Mountains (Dinaridic Ophiolite Belt) west of the Drina-Ivanjica unit yield Late Triassic radiolarian ages. The microfacies characteristics of the radiolarites show pure ribbon radiolarites without crinoids or thin-shelled bivalves. Beside their age and the preservation of the radiolarians this points to a deposition of the radiolarites on top of the oceanic crust of the Neo-Tethys, which started to open in the Late Anisian. South of the study area the ophiolitic mélange (Gostilje-Ljubiš-Visoka-Radoševo mélange) contains a mixture of blocks of 1) oceanic crust, 2) Middle and Upper Triassic ribbon radiolarites, and 3) open marine limestones from the continental slope. On the basis of this composition we can conclude that the Upper Triassic radiolarite clasts derive either from 1) the younger parts of the sedimentary succession above the oceanic crust near the continental slope or, more convincingly 2) the sedimentary cover of ophiolites in a higher nappe position, because Upper Triassic ribbon radiolarites are only expected in more distal oceanic areas. The ophiolitic mélange in the study area overlies different carbonate blocks of an underlying carbonate-clastic mélange (Sirogojno mélange). We date and describe three localities with different Upper Triassic radiolarite clasts in a mélange, which occurs A) on top of Upper Triassic fore-reef to reefal limestones (Dachstein reef), B) between an Upper Triassic reefal limestone block and a Lower Carnian reef limestone (Wetterstein reef), and C) in fissures of an Upper Triassic lagoonal to back-reef limestone (Dachstein lagoon). The sedimentary features point to a sedimentary and not to a tectonic emplacement of the ophiolitic mélange (= sedimentary mélange) filling the rough topography of the topmost carbonate-clastic mélange below. The block spectrum of the underlying and slightly older carbonate-clastic mélange points to a deposition of the sedimentary ophiolitic mélange east of or on top of the Drina-Ivanjica unit.

Hydrogeologic data from the US Geological Survey test wells near Waycross, Ware County, Georgia

USGS Publications Warehouse

Matthews, S.E.; Krause, R.E.

1983-01-01

Two wells were constructed near Waycross, Ware County, Georgia, from July 1980 to May 1981 to collect stratigraphic, structural, geophysical, hydrologic, hydraulic, and geochemical information for the U.S. Geological Survey Tertiary Limestone Regional Aquifer-System Analysis. Data collection included geologic sampling and coring, borehole geophysical logging, packer testing, water-level measuring, water-quality sampling, and aquifer testing. In the study area, the Tertiary limestone aquifer system is about 1,300 feet thick and is confined and overlain by about 610 feet of clastic sediments. The aquifer system consists of limestone, dolomite, and minor evaporites and has high porosity and permeability. A 4-day continuous discharge aquifer test was conducted, from which a transmissivity of about 1 million feet squared per day and a storage coefficient of 0.0001 were calculated. Water from the upper part of the aquifer is of a calcium bicarbonate type. The deeper highly mineralized zone produces a sodium bicarbonate type water in which concentrations of magnesium, sulfate, chloride, sodium, and some trace metals increase with depth. (USGS)

Anatomy of an embayment in an Ordovician epeiric sea, Upper Mississippi Valley, USA

NASA Astrophysics Data System (ADS)

Simo, J. A. Toni; Emerson, Norlene R.; Byers, Charles W.; Ludvigson, Gregory A.

2003-06-01

The integration of stratigraphic, geochemical, and biostratigraphic data from Middle Ordovician carbonates and shales indicates that the North American epeiric sea was partitioned into shelf areas with distinct characteristics. The Upper Mississippi Valley part of the epeiric sea was appraised by using regionally traceable and geochemically “fingerprinted” K-bentonites, as well as detailed lithologic correlation. In the Midcontinent, the Decorah Formation records a time of high clastic sediment influx and abundant freshwater runoff from the Transcontinental Arch that created a salinity-stratified water column and led to episodic dysoxia. Later, relative flooding of the clastic source areas greatly reduced both the clastic sediment and freshwater runoff. As a result, the salinity stratification broke down, oxygenating the seafloor and permitting carbonates to form. Associated with this change, clarity of the water improved and the photic zone expanded, allowing seasonal blooms of Gloeocapsomorpha prisca to occur, resulting in increased burial of organic matter. The increase in G. prisca and total organic carbon coincided with, but lagged behind, a regional δ13C excursion. In addition, the timing of the initiation of the isotopic anomaly is different across the studied area, suggesting that local environmental conditions influenced the isotopic record. Data presented in this study support the partitioning of distinct areas within epeiric seas and the importance of this setting in storing inorganic and organic carbon and recording environmental and biological changes.

Magnetotelluric Data, Central Yucca Flat, Nevada Test Site, Nevada

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

J.M. Williams; B.D. Rodriguez, and T.H. Asch

2005-11-23

Nuclear weapons are integral to the defense of the United States. The U.S. Department of Energy, as the steward of these devices, must continue to gauge the efficacy of the individual weapons. This could be accomplished by occasional testing at the Nevada Test Site (NTS) in Nevada, northwest of Las Vegas. Yucca Flat Basin is one of the testing areas at the NTS. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow in the area subsequent to a nuclear test. Ground-water modelers would like to know more about themore » hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Yucca Flat Corrective Action Unit (CAU). During 2003, the U.S. Geological Survey (USGS) collected and processed Magnetotelluric (MT) and Audio-magnetotelluric (AMT) data at the Nevada Test Site in and near Yucca Flat to help characterize this pre-Tertiary geology. That work will help to define the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal has been to define the upper clastic confining unit (UCCU) in the Yucca Flat area. Interpretation will include a three-dimensional (3-D) character analysis and two-dimensional (2-D) resistivity model. The purpose of this report is to release the MT sounding data for Central Yucca Flat, Profile 1, as shown in figure 1. No interpretation of the data is included here.« less

Magnetotelluric Data, North Central Yucca Flat, Nevada Test Site, Nevada

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

J.M. Williams; B.D. Rodriguez, and T.H. Asch

2005-11-23

Nuclear weapons are integral to the defense of the United States. The U.S. Department of Energy, as the steward of these devices, must continue to gauge the efficacy of the individual weapons. This could be accomplished by occasional testing at the Nevada Test Site (NTS) in Nevada, northwest of Las Vegas. Yucca Flat Basin is one of the testing areas at the NTS. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow in the area subsequent to a nuclear test. Ground-water modelers would like to know more about themore » hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Yucca Flat Corrective Action Unit (CAU). During 2003, the U.S. Geological Survey (USGS) collected and processed Magnetotelluric (MT) and Audio-magnetotelluric (AMT) data at the Nevada Test Site in and near Yucca Flat to help characterize this pre-Tertiary geology. That work will help to define the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal has been to define the upper clastic confining unit (UCCU) in the Yucca Flat area. Interpretation will include a three-dimensional (3-D) character analysis and two-dimensional (2-D) resistivity model. The purpose of this report is to release the MT sounding data for north central Yucca Flat, Profile 7, as shown in Figure 1. No interpretation of the data is included here.« less

Magnetotelluric Data, Northern Frenchman Flat, Nevada Test Site Nevada

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

J.M. Williams; B.D. Rodriguez, and T. H. Asch

2005-11-23

Nuclear weapons are integral to the defense of the United States. The U.S. Department of Energy, as the steward of these devices, must continue to gauge the efficacy of the individual weapons. This could be accomplished by occasional testing at the Nevada Test Site (NTS) in Nevada, northwest of Las Vegas. Yucca Flat Basin is one of the testing areas at the NTS. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow in the area subsequent to a nuclear test. Ground-water modelers would like to know more about themore » hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Yucca Flat Corrective Action Unit (CAU). During 2003, the U.S. Geological Survey (USGS) collected and processed Magnetotelluric (MT) and Audio-magnetotelluric (AMT) data at the Nevada Test Site in and near Yucca Flat to help characterize this pre-Tertiary geology. That work will help to define the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal has been to define the upper clastic confining unit (UCCU) in the Yucca Flat area. Interpretation will include a three-dimensional (3-D) character analysis and two-dimensional (2-D) resistivity model. The purpose of this report is to release the MT sounding data for Frenchman Flat Profile 3, as shown in Figure 1. No interpretation of the data is included here.« less

Magnetotelluric Data, Across Quartzite Ridge, Nevada Test Site, Nevada

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

J.M. Williams; B.D. Rodriguez, and T.H. Asch

2005-11-23

Nuclear weapons are integral to the defense of the United States. The U.S. Department of Energy, as the steward of these devices, must continue to gauge the efficacy of the individual weapons. This could be accomplished by occasional testing at the Nevada Test Site (NTS) in Nevada, northwest of Las Vegas. Yucca Flat Basin is one of the testing areas at the NTS. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow in the area subsequent to a nuclear test. Ground-water modelers would like to know more about themore » hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Yucca Flat Corrective Action Unit (CAU). During 2003, the U.S. Geological Survey (USGS) collected and processed Magnetotelluric (MT) and Audio-magnetotelluric (AMT) data at the Nevada Test Site in and near Yucca Flat to help characterize this pre-Tertiary geology. That work will help to define the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal has been to define the upper clastic confining unit (UCCU) in the Yucca Flat area. Interpretation will include a three-dimensional (3-D) character analysis and two-dimensional (2-D) resistivity model. The purpose of this report is to release the MT soundings across Quartzite Ridge, Profiles 5, 6a, and 6b, as shown in Figure 1. No interpretation of the data is included here.« less

Magnetotelluric Data, Southern Yucca Flat, Nevada Test Site, Nevada

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

J.M. Williams; B.D. Rodriguez, and T.H. Asch

2005-11-23

Nuclear weapons are integral to the defense of the United States. The U.S. Department of Energy, as the steward of these devices, must continue to gauge the efficacy of the individual weapons. This could be accomplished by occasional testing at the Nevada Test Site (NTS) in Nevada, northwest of Las Vegas. Yucca Flat Basin is one of the testing areas at the NTS. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow in the area subsequent to a nuclear test. Ground-water modelers would like to know more about themore » hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Yucca Flat Corrective Action Unit (CAU). During 2003, the U.S. Geological Survey (USGS) collected and processed Magnetotelluric (MT) and Audio-magnetotelluric (AMT) data at the Nevada Test Site in and near Yucca Flat to help characterize this pre-Tertiary geology. That work will help to define the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal has been to define the upper clastic confining unit (UCCU) in the Yucca Flat area. Interpretation will include a three-dimensional (3-D) character analysis and two-dimensional (2-D) resistivity model. The purpose of this report is to release the MT sounding data for Southern Yucca Flat, Profile 4, as shown in Figure 1. No interpretation of the data is included here.« less

Magnetotelluric Data, Northern Yucca Flat, Nevada Test Site, Nevada

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

J.M. Williams; B.D. Rodriguez, and T.H. Asch

2005-11-23

Nuclear weapons are integral to the defense of the United States. The U.S. Department of Energy, as the steward of these devices, must continue to gauge the efficacy of the individual weapons. This could be accomplished by occasional testing at the Nevada Test Site (NTS) in Nevada, northwest of Las Vegas. Yucca Flat Basin is one of the testing areas at the NTS. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow in the area subsequent to a nuclear test. Ground-water modelers would like to know more about themore » hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Yucca Flat Corrective Action Unit (CAU). During 2003, the U.S. Geological Survey (USGS) collected and processed Magnetotelluric (MT) and Audio-magnetotelluric (AMT) data at the Nevada Test Site in and near Yucca Flat to help characterize this pre-Tertiary geology. That work will help to define the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal has been to define the upper clastic confining unit (UCCU) in the Yucca Flat area. Interpretation will include a three-dimensional (3-D) character analysis and two-dimensional (2-D) resistivity model. The purpose of this report is to release the MT sounding data for Profile 2, (fig. 1), located in the northern Yucca Flat area. No interpretation of the data is included here.« less

Stratigraphy and depositional environment of upper Cambrian Red Lion Formation, southwestern Montana

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

Hayden, L.L.; Bush, J.H.

1987-08-01

The Red Lion Formation was examined along a northwest-southeast transect from Missoula to Bozeman, Montana. Lateral equivalents are the Snowy Range Formation east of Bozeman and the upper Fishtrap Dolomite in northwest Montana. The basal Dry Creek Member (0-5 m) consists of shale interbedded with quartz siltstones and sandstones. The overlying Sage Member, up to 115 meters in thickness, is characterized by ribbon carbonate beds containing lime mudstone and quartzose calcisiltite couplets arranged in fining-upward sequences 1-5 cm thick. Couplets are interlayered in places with thin (1-5 cm) to medium bedded (6-70 cm) units of laminated and non-laminated calcareous siltstones,more » flat-pebble conglomerates, trilobite packstones, cryptalgal boundstones, bioturbated lime mudstones and shales. In places, the upper Sage contains columnar and domal algal features. The Red Lion Formation is considered to be one Grand Cycle with the Dry Creek representing a lower inner detrital half-cycle and the Sage an upper carbonate half-cycle. The Dry Creek formed as the result of a westward clastic pulse from the inner detrital belt across an intrashelf basin onto outer middle carbonate peritidal complexes of the underlying Pilgrim Formation. Lower Sage ribbon rocks were deposited in storm-crossed, below wave-base areas. During deposition of the upper Sage, shallowing formed discontinuous algal-peritidal complexes over much of western and central Montana. These complexes were less extensive than earlier Cambrian buildups owing to slower rates of basin subsidence and clastic input suppressing carbonate production.« less

Mixing of biogenic siliceous and terrigenous clastic sediments: South Belridge field and Beta field, California

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

Schwartz, D.E.

1990-05-01

The intermixing and interbedding of biogenically derived siliceous sediment with terrigenous clastic sediment in reservoirs of upper Miocene age provides both reservoir rock and seal and influences productivity by affecting porosity and permeability. Miocene reservoirs commonly contain either biogenic-dominated cyclic diatomite, porcelanite, or chert (classic Monterey Formation) or clastic-dominated submarine fan sequences with interbedded or intermixed siliceous members of biogenic origin. Biogenic-clastic cycles, 30-180 ft thick, at South Belridge field were formed by episodic influx of clastic sediment from distant submarine fans mixing with slowly accumulating diatomaceous ooze. The cycles consist of basal silt and pelletized massive diatomaceous mudstone, overlainmore » by burrowed, faintly bedded clayey diatomite and topped by laminated diatomite. Cycle tops have higher porosity and permeability, lower grain density, and higher oil saturation than clay and silt-rich portions of the cycles. Submarine fan sediments forming reservoirs at the Beta field are comprised of interbedded sands and silts deposited in a channelized middle fan to outer fan setting. Individual turbidites display fining-upward sequences, with oil-bearing sands capped by wet micaceous silts. Average sands are moderately to poorly sorted, fine- to medium-grained arkosic arenites. Sands contain pore-filling carbonate and porcelaneous cements. Porcelaneous cement consists of a mixture of opal-A, opal-CT, and chert with montmorillonite and minor zeolite. This cement is an authigenic material precipitated in intergranular pore space. The origin of the opal is biogenic, with recrystallization of diatom frustules (opal-A) into opal-CT lepispheres and quartz crystals. Porcelaneous cement comprises 4-21% of the bulk volume of the rock. Seventy percent of the bulk volume of the cement is micropore space.« less

Depositional sequence stratigraphy and architecture of the cretaceous ferron sandstone: Implications for coal and coalbed methane resources - A field excursion

USGS Publications Warehouse

Garrison, J.R.; Van Den, Bergh; Barker, C.E.; Tabet, D.E.

1997-01-01

This Field Excursion will visit outcrops of the fluvial-deltaic Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale, known as the Last Chance delta or Upper Ferron Sandstone. This field guide and the field stops will outline the architecture and depositional sequence stratigraphy of the Upper Ferron Sandstone clastic wedge and explore the stratigraphic positions and compositions of major coal zones. The implications of the architecture and stratigraphy of the Ferron fluvial-deltaic complex for coal and coalbed methane resources will be discussed. Early works suggested that the southwesterly derived deltaic deposits of the the upper Ferron Sandstone clastic wedge were a Type-2 third-order depositional sequence, informally called the Ferron Sequence. These works suggested that the Ferron Sequence is separated by a type-2 sequence boundary from the underlying 3rd-order Hyatti Sequence, which has its sediment source from the northwest. Within the 3rd-order depositional sequence, the deltaic events of the Ferron clastic wedge, recognized as parasequence sets, appear to be stacked into progradational, aggradational, and retrogradational patterns reflecting a generally decreasing sediment supply during an overall slow sea-level rise. The architecture of both near-marine facies and non-marine fluvial facies exhibit well defined trends in response to this decrease in available sediment. Recent studies have concluded that, unless coincident with a depositional sequence boundary, regionally extensive coal zones occur at the tops of the parasequence sets within the Ferron clastic wedge. These coal zones consist of coal seams and their laterally equivalent fissile carbonaceous shales, mudstones, and siltstones, paleosols, and flood plain mudstones. Although the compositions of coal zones vary along depositional dip, the presence of these laterally extensive stratigraphic horizons, above parasequence sets, provides a means of correlating and defining the tops of depositional parasequence sets in both near-marine and non-marine parts of fluvial-deltaic depositional sequences. Ongoing field studies, based on this concept of coal zone stratigraphy, and detailed stratigraphic mapping, have documented the existence of at least 12 parasequence sets within the Last Chance delta clastic wedge. These parasequence sets appear to form four high frequency, 4th-order depositional sequences. The dramatic erosional unconformities, associated with these 4th-order sequence boundaries, indicate that there was up to 20-30 m of erosion, signifying locally substantial base-level drops. These base-level drops were accompanied by a basin ward shift in paleo-shorelines by as much as 5-7 km. These 4th-order Upper Ferron Sequences are superimposed on the 3rd-order sea-level rise event and the 3rd-order, sediment supply/accommodation space driven, stratigraphie architecture of the Upper Ferron Sandstone. The fluvial deltaic architecture shows little response to these 4th-order sea-level events. Coal zones generally thicken landward relative to the mean position of the landward pinch-out of the underlying parasequence set, but after some distance landward, they decrease in thickness. Coal zones also generally thin seaward relative to the mean position of the landward pinch-out of the underlying parasequence set. The coal is thickest in the region between this landward pinch-out and the position of maximum zone thickness. Data indicate that the proportion of coal in the coal zone decreases progressively landward from the landward pinch-out. The effects of differential compaction and differences in original pre-peat swamp topography have the effect of adding perturbations to the general trends. These coal zone systematics have major impact on approaches to exploration and production, and the resource accessment of both coal and coalbed methane.

Geology and hydrocarbon potential in the state of Qatar, Arabian Gulf

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

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

The state of Qatar is situated in the southern Arabian Gulf and covers an area of 12,000 km{sup 2}. It is formed by a large, broad anticline, which is part of the regional south-southwest-north-northeast-trending Qatar-South Fars arch. The arch separates the two Infracambrian salt basins. The Dukhan field was the first discovery, made in 1939, in the Upper Jurassic limestones. Since then, a series of discoveries have been made so that Qatar has become one of the leading OPEC oil states. Hydrocarbon accumulations are widely dispersed throughout the stratigraphic column from upper Paleozoic to Cretaceous producing strata. The most prolificmore » reservoirs are the Permian and Mesozoic shelf carbonate sequences. Minor clastic reservoirs occur in the Albian and Paleozoic sequences. Seals, mainly anhydrite and shale. occur both intraformationally and regionally. Several stratigraphic intervals contain source rocks or potential source rocks. The Silurian shales arc the most likely source of the hydrocarbon stored in the upper Paleozoic clastics and carbonates. The upper Oxfordian-middle Kimmeridgian rocks formed in the extensive starved basin during the Mesozoic period of sea level rise. Total organic carbon ranges between 1 and 6%, with the sulfur content approximately 9%. The source material consists of sapropelic liptodetrinite and algae. The geological background of the sedimentary facies through geologic time, stratigraphy, and structural evolution which control source, and the subsequent timing and migration of large-scale hydrocarbon generation are presented in detail.« less

Deep-water facies and petrography of the Galoc clastic unit, offshore Palawan, Philippines (south China Sea)

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

Link, M.H.; Helmold, K.P.

1988-02-01

The lower Miocene Galoc clastic unit, offshore Palawan, Philippines, is about 500-600 ft thick. The unit overlies the Galoc Limestone and is overlain by the Pelitic Pagasa Formation. The Galoc clastic unit consists of alternating quartzose sandstone, mudstone, and resedimented carbonate deposited at bathyal depths, mainly as turbidites. The deep-water deposits are confined to the axis of a northeast-trending trough in which slope, submarine channel, interchannel, depositional lobe, slump, and basinal facies are recognized. Eroded shallow-marine carbonate lithoclasts are commonly incorporated within the siliciclastic turbidites. The main reservoir sandstones occur in submarine channels and depositional lobes. The sandstones are texturallymore » submature, very fine to medium-grained feldspathic litharenites and subarkoses. The sandstones have detrital modes of Q78:F11:L11 and Qm51:F11:Lt38, with partial modes of the monocrystalline components of Qm82:P13:K5. Lithic fragments include chert, shale, schist, volcanic rock fragments, and minor plutonic rock fragments. Porosity in the better reservoir sandstones ranges from 11 to 25%, and calcite is the dominant cement. Dissolution textures and inhomogeneity of calcite distribution suggest that at least half of the porosity in the sandstones has formed through the leaching of calcite cement and labile framework grains. A source terrain of quartzo-feldspathic sediments and metasediments, chert, volcanics, and acid-intermediate plutonic rocks is visualized.« less

Pyroclastic Activity at Home Plate in Gusev Crater, Mars

NASA Technical Reports Server (NTRS)

Squyres, S. W.; Aharonson, O.; Clark, B. S.; Cohen, B.; Crumpler, L.; deSouza, P. A.; Farrand, W. H.; Gellert, R.; Grant, J.; Grotzinger, J. P.;

Pyroclastic activity at home plate in Gusev crater, Mars

USGS Publications Warehouse

Squyres, S. W.; Aharonson, O.; Clark, B. C.; Cohen, B. A.; Crumpler, L.; de Souza, P.A.; Farrand, W. H.; Gellert, Ralf; Grant, J.; Grotzinger, J.P.; Haldemann, A.F.C.; Johnson, J. R.; Klingelhofer, G.; Lewis, K.W.; Li, R.; McCoy, T.; McEwen, A.S.; McSween, H.Y.; Ming, D. W.; Moore, Johnnie N.; Morris, R.V.; Parker, T.J.; Rice, J. W.; Ruff, S.; Schmidt, M.; Schroder, C.; Soderblom, L.A.; Yen, A.

2007-01-01

Home Plate is a layered plateau in Gusev crater on Mars. It is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. A coarse-grained lower unit lies under a finer-grained upper unit. Textural observations indicate that the lower strata were emplaced in an explosive event, and geochemical considerations favor an explosive volcanic origin over an impact origin. The lower unit likely represents accumulation of pyroclastic materials, whereas the upper unit may represent eolian reworking of the same pyroclastic materials.

Petrography and geochemistry of clastic rocks within the Inthanon zone, northern Thailand: Implications for Paleo-Tethys subduction and convergence

NASA Astrophysics Data System (ADS)

Hara, Hidetoshi; Kunii, Miyuki; Hisada, Ken-ichiro; Ueno, Katsumi; Kamata, Yoshihito; Srichan, Weerapan; Charusiri, Punya; Charoentitirat, Thasinee; Watarai, Megumi; Adachi, Yoshiko; Kurihara, Toshiyuki

2012-11-01

The provenance, source rock compositions, and sediment supply system for a convergence zone of the Paleo-Tethys were reconstructed based on the petrography and geochemistry of clastic rocks of the Inthanon Zone, northern Thailand. The clastic rocks are classified into two types based on field and microscopic observations, the modal composition of sandstone, and mineral compositions: (1) lithic sandstone and shale within mélange in a Permo-Triassic accretionary complex; and (2) Carboniferous quartzose sandstone and mudstone within the Sibumasu Block. Geochemical data indicate that the clastic rocks of the mélange were derived from continental island arc and continental margin settings, which correspond to felsic volcanic rocks within the Sukhothai Zone and quartz-rich fragments within the Indochina Block, respectively. The results of a mixing model indicate the source rocks were approximately 35% volcanic rocks of the Sukhothai Zone and 65% craton sandstone and upper continental crust of the Indochina Block. In contrast, Carboniferous quartzose sedimentary rocks within the Sibumasu Block originated from a continental margin, without a contribution from volcanic rocks. In terms of Paleo-Tethys subduction, a continental island arc in the Sukhothai Zone evolved in tandem with Late Permian-Triassic forearc basins and volcanic activity during the Middle-early Late Triassic. The accretionary complex formed contemporaneously with the evolution of continental island arc during the Permo-Triassic, supplied with sediment from the Sukhothai Zone and the Indochina Block.

Physical stratigraphy and hydrostratigraphy of Upper Cretaceous and Paleocene sediments, Burke and Screven Counties, Georgia

USGS Publications Warehouse

Falls, W.F.; Baum, J.S.; Prowell, D.C.

1997-01-01

Six geologic units are recognized in the Cretaceous and the Paleocene sediments of eastern Burke and Screven Counties in Georgia on the basis of lithologic, geophysical, and paleontologic data collected from three continuously cored testholes in Georgia and one testhole in South Carolina. The six geologic units are separated by regional unconformities and are designated from oldest to youngest as the Cape Fear Formation, the Middendorf Formation, the Black Creek Group (undivided), and the Steel Creek Formation in the Upper Cretaceous section, and the Ellenton and the Snapp Formations in the Paleocene section. The geologic units provide a spatial and temporal framework for the identification and correlation of a basal confining unit beneath the Midville aquifer system and five aquifers and five confining units in the Dublin and the Midville aquifer systems. The Dublin aquifer system is divided hydrostratigraphically into the Millers Pond, the upper Dublin, and the lower Dublin aquifers. The Midville aquifer system is divided hydrostratigraphically into the upper and the lower Midville aquifers. The fine-grained sediments of the Millers Pond, the lower Dublin, and the lower Midville confining units are nonmarine deposits and are present in the upper part of the Snapp Formation, the Black Creek Group (undivided), and the Middendorf Formation, respectively. Hydrologic data for specific sets of monitoring wells at the Savannah River Site in South Carolina and the Millers Pond site in Georgia confirm that these three units are leaky confining units and locally impede vertical ground-water flow between adjacent aquifers. The fine-grained sediments of the upper Dublin and the upper Midville confining units are marine-deltaic deposits of the Ellenton Formation and the Black Creek Group (undivided), respectively. Hydrologic data confirm that the upper Dublin confining unit regionally impedes vertical ground-water flow on both sides of the Savannah River. The upper Midville confining unit impedes vertical ground-water flow in the middle and downdip parts of the study area and is a leaky confining unit in the updip part of the study area. Recognition of the upper Dublin confining unit as a regional confining unit between the Millers Pond and the upper Dublin aquifers also confirms that the Millers Pond aquifer is a separate hydrologic unit from the rest of the Dublin aquifer system. This multi-aquifer framework increases the vertical hydrostratigraphic resolution of hydraulic properties and gradients in the Dublin and Midville aquifer systems for the investigation of ground-water flow beneath the Savannah River in the vicinity of the U.S. Department of Energy Savannah River Site.

Provenance analysis and tectonic setting of the Triassic clastic deposits in Western Chukotka, Northeast Russia

NASA Astrophysics Data System (ADS)

Tuchkova, M. I.; Sokolov, S.; Kravchenko-Berezhnoy, I. R.

2009-09-01

The study area is part of the Anyui subterrane of the Chukotka microplate, a key element in the evolution of the Amerasia Basin, located in Western Chukotka, Northeast Russia. The subterrane contains variably deformed, folded and cleaved rhythmic Triassic terrigenous deposits which represent the youngest stage of widespread marine deposition which form three different complexes: Lower-Middle Triassic, Upper Triassic (Carnian) and Upper Triassic (Norian). All of the complexes are represented by rhythmic interbeds of sandstone, siltstone and mudstone. Macrofaunas are not numerous, and in some cases deposits are dated by analogy to, or by their relationship with, other units dated with macrofaunas. The deposits are composed of pelagic sediments, low-density flows, high-density flows, and shelf facies associations suggesting that sedimentation was controlled by deltaic progradation on a continental shelf and subsequent submarine fan sedimentation at the base of the continental slope. Petrographic study of the mineral composition indicates that the sandstones are lithic arenites. Although the Triassic sandstones appear similar in outcrop and by classification, the constituent rock fragments are of diverse lithologies, and change in composition from lower grade metamorphic rocks in the Lower-Middle Triassic to higher grade metamorphic rocks in the Upper Triassic. This change suggests that the Triassic deposits represent an unroofing sequence as the source of the clastic material came from more deeply buried rocks with time.

Radiolarian biochronology of upper Anisian to upper Ladinian (Middle Triassic) blocks and tectonic slices of volcano-sedimentary successions in the Mersin Mélange, southern Turkey: New insights for the evolution of Neotethys

NASA Astrophysics Data System (ADS)

Tekin, U. Kagan; Bedi, Yavuz; Okuyucu, Cengiz; Göncüoglu, M. Cemal; Sayit, Kaan

2016-12-01

The Mersin Ophiolitic Complex located in southern Turkey comprises two main structural units; the Mersin Mélange, and a well-developed ophiolite succession with its metamorphic sole. The Mersin Mélange is a sedimentary complex including blocks and tectonic slices of oceanic litosphere and continental crust in different sizes. Based on different fossil groups (Radiolaria, Conodonta, Foraminifera and Ammonoidea), the age of these blocks ranges from Early Carboniferous to early Late Cretaceous. Detailed fieldwork in the central part of the Mersin Mélange resulted in identification of a number of peculiar blocks of thick basaltic pillow-and massive lava sequences alternating with pelagic-clastic sediments and radiolarian cherts. The oldest ages obtained from the radiolarian assemblages from the pelagic sediments transitional to the volcano-sedimentary succession in some blocks are middle to late Late Anisian. These pelagic sediments are overlain by thick sandstones of latest Anisian to middle Early Ladinian age. In some blocks, sandstones are overlain by clastic and pelagic sediments with lower Upper to middle Upper Ladinian radiolarian fauna. Considering the litho- and biostratigraphical data from Middle Triassic successions in several blocks in the Mersin Mélange, it is concluded that they correspond mainly to the blocks/slices of the Beysehir-Hoyran Nappes, which were originated from the southern margin of the Neotethyan Izmir-Ankara Ocean. As the pre-Upper Anisian basic volcanics are geochemically evaluated as back-arc basalts, this new age finding suggest that a segment of the Izmir-Ankara branch of the Neotethys was already open prior to Middle Triassic and was the site of intraoceanic subduction.

Summary and evaluation of hydraulic property data available for the Hanford Site upper basalt confined aquifer system

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

Spane, F.A. Jr.; Vermeul, V.R.

Pacific Northwest Laboratory, as part of the Hanford Site Ground-Water Surveillance Project, examines the potential for offsite migration of contamination within the upper basalt confined aquifer system. For the past 40 years, hydrologic testing of the upper basalt confined aquifer has been conducted by a number of Hanford Site programs. Hydraulic property estimates are important for evaluating aquifer flow characteristics (i.e., ground-water flow patterns, flow velocity, transport travel time). Presented are the first comprehensive Hanford Site-wide summary of hydraulic properties for the upper basalt confined aquifer system (i.e., the upper Saddle Mountains Basalt). Available hydrologic test data were reevaluated usingmore » recently developed diagnostic test analysis methods. A comparison of calculated transmissivity estimates indicates that, for most test results, a general correspondence within a factor of two between reanalysis and previously reported test values was obtained. For a majority of the tests, previously reported values are greater than reanalysis estimates. This overestimation is attributed to a number of factors, including, in many cases, a misapplication of nonleaky confined aquifer analysis methods in previous analysis reports to tests that exhibit leaky confined aquifer response behavior. Results of the test analyses indicate a similar range for transmissivity values for the various hydro-geologic units making up the upper basalt confined aquifer. Approximately 90% of the calculated transmissivity values for upper basalt confined aquifer hydrogeologic units occur within the range of 10{sup 0} to 10{sup 2} m{sup 2}/d, with 65% of the calculated estimate values occurring between 10{sup 1} to 10{sup 2} m{sup 2}d. These summary findings are consistent with the general range of values previously reported for basalt interflow contact zones and sedimentary interbeds within the Saddle Mountains Basalt.« less

The paleomagnetism of clastic and precipitate deposits in limestone and dolomite caves

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

Latham, A.G.; Ford, D.C.

1991-03-01

Clastic sediments and calcite precipitates (stalagmites, flowstones, etc.) are abundant in modern limestone caves and normally are the dominant infillings in buried (paleokarst) caves. Clastic sediment fillings are chiefly of fluviatile or local breakdown origin, but lacustrine, colluvial, eolian, and glacial deposits are known. Paleomagnetism has been studied in the fluviatile and lacustrine types: (1) reversal stratigraphy aids dating of geomorphic and paleoclimatic events in the late Pliocene/Pleistocene; (2) fine magnetostratigraphy has yielded estimates of the westward drift. Calcite precipitates (speleothems) may display natural remanent magnetism of either depositional (DRM) or chemical (CRM) origin. NRMs of modern speleothems are primary,more » not diagenetic; CRMs are invariably associated with the degradation of surface organic matter. (1) Coarse reversal stratigraphy dates geomorphic, etc., events and erosion rates. (2) Fine stratigraphy combined with {sup 230}Th:{sup 234}U dating gives high precision estimates of secular variation, westward drift, and rate of change of geomagnetic anomalies in upper Pleistocene and Holocene deposits. Magnetostratigraphy of paleokarst speleothem fillings associated with hydrocarbons in Ordovician limestones suggest a Permian age for the karstification. Potential applications of magnetostratigraphy to paleokarst deposits of many different scales are considerable.« less

Sandy contourite drift in the late Miocene Rifian Corridor (Morocco): Reconstruction of depositional environments in a foreland-basin seaway

NASA Astrophysics Data System (ADS)

Capella, W.; Hernández-Molina, F. J.; Flecker, R.; Hilgen, F. J.; Hssain, M.; Kouwenhoven, T. J.; van Oorschot, M.; Sierro, F. J.; Stow, D. A. V.; Trabucho-Alexandre, J.; Tulbure, M. A.; de Weger, W.; Yousfi, M. Z.; Krijgsman, W.

2017-06-01

The Rifian Corridor was a seaway between the Atlantic Ocean and the Mediterranean Sea during the late Miocene. The seaway progressively closed, leading to the Messinian Salinity Crisis in the Mediterranean Sea. Despite the key palaeogeographic importance of the Rifian Corridor, patterns of sediment transport within the seaway have not been thoroughly studied. In this study, we investigated the upper Miocene sedimentation and bottom current pathways in the South Rifian Corridor. The planktic and benthic foraminifera of the upper Tortonian and lower Messinian successions allow us to constrain the age and palaeo-environment of deposition. Encased in silty marls deposited at 150-300 m depth, there are (i) 5 to 50 m thick, mainly clastic sandstone bodies with unidirectional cross-bedding; and (ii) 50 cm thick, mainly clastic, tabular sandstone beds with bioturbation, mottled silt, lack of clear base or top, and bi-gradational sequences. Furthermore, seismic facies representing elongated mounded drifts and associated moat are present at the western mouth of the seaway. We interpret these facies as contourites: the products of a westward sedimentary drift in the South Rifian Corridor. The contourites are found only on the northern margin of the seaway, thus suggesting a geostrophic current flowing westward along slope and then northward. This geostrophic current may have been modulated by tides. By comparing these fossil examples with the modern Gulf of Cadiz, we interpret these current-dominated deposits as evidence of late Miocene Mediterranean overflow into the Atlantic Ocean, through the Rifian Corridor. This overflow may have affected late Miocene ocean circulation and climate, and the overflow deposits may represent one of the first examples of mainly clastic contourites exposed on land.

Clastic dikes of Heart Mountain fault breccia, northwestern Wyoming, and their significance

USGS Publications Warehouse

Pierce, W.G.

1979-01-01

Structural features in northwestern Wyoming indicate that the Heart Mountain fault movement was an extremely rapid, cataclysmic event that created a large volume of carbonate fault breccia derived entirely from the lower part of the upper plate. After fault movement had ceased, much of the carbonate fault breccia, here called calcibreccia, lay loose on the resulting surface of tectonic denudation. Before this unconsolidated calcibreccia could be removed by erosion, it was buried beneath a cover of Tertiary volcanic rocks: the Wapiti Formation, composed of volcanic breccia, poorly sorted volcanic breccia mudflows, and lava flows, and clearly shown in many places by inter lensing and intermixing of the calcibreccia with basal volcanic rocks. As the weight of volcanic overburden increased, the unstable water-saturated calcibreccia became mobile and semifluid and was injected upward as dikes into the overlying volcanic rocks and to a lesser extent into rocks of the upper plate. In some places the lowermost part of the volcanic overburden appears to have flowed with the calcibreccia to form dike like bodies of mixed volcanic rock and calcibreccia. One calcibreccia dike even contains carbonized wood, presumably incorporated into unconsolidated calcibreccia on the surface of tectonic denudation and covered by volcanic rocks before moving upward with the dike. Angular xenoliths of Precambrian rocks, enclosed in another calcibreccia dike and in an adjoining dikelike mass of volcanic rock as well, are believed to have been torn from the walls of a vent and incorporated into the basal part of the Wapiti Formation overlying the clastic carbonate rock on the fault surface. Subsequently, some of these xenoliths were incorporated into the calcibreccia during the process of dike intrusion. Throughout the Heart Mountain fault area, the basal part of the upper-plate blocks or masses are brecciated, irrespective of the size of the blocks, more intensely at the base and in places extending upward for several tens of meters. North of Republic Mountain a small 25-m-high upper-plate mass, brecciated to some degree throughout, apparently moved some distance along the Heart Mountain fault as brecciated rock. Calcibreccia dikes intrude upward from the underlying 2 m of fault breccia into the lower part of the mass and also from its top into the overlying volcanic rocks; an earthquake-related mechanism most likely accounts for the observed features of this deformed body. Calcibreccia dikes are more common within the bedding-plane phase of the Heart Mountain fault but also occur in its transgressive and former land-surface phases. Evidence that the Wapiti Formation almost immediately buried loose, unconsolidated fault breccia that was the source of the dike rock strongly suggests a rapid volcanic deposition over the area in which clastic dikes occur, which is at least 75 km long. Clastic dikes were injected into both the upper-plate and the volcanic rocks at about the same time, after movement on the Heart Mouuntain fault had ceased, and therefore do not indicate a fluid-flotation mechanism for the Heart Mountain fault. The difference between contacts of the clastic dikes with both indurated and unconsolidated country rock is useful in field mapping at localities where it is difficult to distinguish between volcanic rocks of the Cathedral Cliffs and Lamar River Formations, and the Wapiti Formation. Thus, calcibreccia dikes in the Cathedral Cliffs and Lamar River Formations show a sharp contact because the country rock solidified prior to fault movement, whereas calcibreccia dikes in the Wapiti Formation in many instances show a transitional or semifluid contact because the country rock was still unconsolidated or semifluid at the time of dike injection.

Stratigraphic architecture and depositional history of lower Miocene, Planulina Zone, Southern Louisiana

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

Gates, B.C.; Galloway, W.E.

1988-01-01

The Planulina zone is a wedge of clastic sediment positioned between the Anahuac shale below and the Oakville sandstone interval above. Planulna sediments were deposited on an erosional surface, during a general rise in the sea level, and formed a retrogradational wedge. Within the study area, the Planulina zone consists of two large depositional complexes: the Mud Lake complex in west Cameron Parish, Louisiana, and the East Cameron complex in east Cameron Parish. The lowermost depositional sequence in the East Cameron complex is preserved in a network of submarine canyons that were eroded into the upper slope. Framework sands weremore » deposited in channel systems confined to the axis of the canyons, and the sands are encased in marine shale containing benthonic foraminifera indicative of an upper to middle slope paleoenvironment. Two younger depositional sequences overlie the submarine canyon facies and were deposited by deltaic systems that prograded basinward. A zone of expansion extends east to west through the Planulina interval and is named the ''Planulina flexure.'' The flexure is a large fault located at the relict shelf edge and soles out downdip inn the Anahuac shale. Several thousand feet of sediment downthrown on the flexure is equivalent to several hundred feet upthrown, and the flexure represented the boundary dividing updip deltaic processes from downdip slope processes during the beginning of Planulina deposition. The Planulina depositional history and stratigraphic architecture are directly related to the displacement along the flexure and the structural deformation of the underlying Anahuac shale.« less

Depositional facies, environments and sequence stratigraphic interpretation of the Middle Triassic-Lower Cretaceous (pre-Late Albian) succession in Arif El-Naga anticline, northeast Sinai, Egypt

NASA Astrophysics Data System (ADS)

El-Azabi, M. H.; El-Araby, A.

2005-01-01

The Middle Triassic-Lower Cretaceous (pre-Late Albian) succession of Arif El-Naga anticline comprises various distinctive facies and environments that are connected with eustatic relative sea-level changes, local/regional tectonism, variable sediment influx and base-level changes. It displays six unconformity-bounded depositional sequences. The Triassic deposits are divided into a lower clastic facies (early Middle Triassic sequence) and an upper carbonate unit (late Middle- and latest Middle/early Late Triassic sequences). The early Middle Triassic sequence consists of sandstone with shale/mudstone interbeds that formed under variable regimes, ranging from braided fluvial, lower shoreface to beach foreshore. The marine part of this sequence marks retrogradational and progradational parasequences of transgressive- and highstand systems tract deposits respectively. Deposition has taken place under warm semi-arid climate and a steady supply of clastics. The late Middle- and latest Middle/early Late Triassic sequences are carbonate facies developed on an extensive shallow marine shelf under dry-warm climate. The late Middle Triassic sequence includes retrogradational shallow subtidal oyster rudstone and progradational lower intertidal lime-mudstone parasequences that define the transgressive- and highstand systems tracts respectively. It terminates with upper intertidal oncolitic packstone with bored upper surface. The next latest Middle/early Late Triassic sequence is marked by lime-mudstone, packstone/grainstone and algal stromatolitic bindstone with minor shale/mudstone. These lower intertidal/shallow subtidal deposits of a transgressive-systems tract are followed upward by progradational highstand lower intertidal lime-mudstone deposits. The overlying Jurassic deposits encompass two different sequences. The Lower Jurassic sequence is made up of intercalating lower intertidal lime-mudstone and wave-dominated beach foreshore sandstone which formed during a short period of rising sea-level with a relative increase in clastic supply. The Middle-Upper Jurassic sequence is represented by cycles of cross-bedded sandstone topped with thin mudstone that accumulated by northerly flowing braided-streams accompanying regional uplift of the Arabo-Nubian shield. It is succeeded by another regressive fluvial sequence of Early Cretaceous age due to a major eustatic sea-level fall. The Lower Cretaceous sequence is dominated by sandy braided-river deposits with minor overbank fines and basal debris flow conglomerate.

Analysis of fractures from borehole televiewer logs in a 500m deep hole at Xiaguan, Yunnan province, Southwest China

USGS Publications Warehouse

Zhai, Qingshan; Springer, J.E.; Zoback, M.D.

1990-01-01

Fractures from a 500 m deep hole in the Red River fault zone were analyzed using an ultrasonic borehole televiewer. Four hundred and eighty individual fractures were identified between 19 m and 465 m depth. Fracture frequency had no apparent relation to the major stratigraphic units and did not change systematically with depth. Fracture orientation, however, did change with stratigraphic position. The borehole intersected 14 m of Cenozoic deposits, 363 m of lower Ordovician clastic sediments, and 106 m of older ultramafic intrusions. The clastic sequence was encountered again at a depth of 484 m, suggesting a large fault displacement. Fractures in the top 162 m of the sedimentary section appear randomly distributed. Below that depth, they are steeply dipping with northerly and north-westerly strikes, parallel to the major active faults in the region. Fractures in the ultramafic section strike roughly eastwest and are steeply dipping. These orientations are confined to the ultramafic section and are parallel to an older, inactive regional fault set. ?? 1990.

Dating the Gaofan and Hutuo Groups - Targets to investigate the Paleoproterozoic Great Oxidation Event in North China

NASA Astrophysics Data System (ADS)

Peng, Peng; Feng, Lianjun; Sun, Fengbo; Yang, Shuyan; Su, Xiangdong; Zhang, Zhiyue; Wang, Chong

2017-05-01

There are several sedimentary units in North China that are proposed to be associated with the Paleoproterozoic Great Oxidation Event (GOE) and/or subsequent events; however, few of them have been precisely dated. In this study, deposition age of the greenschist facies Gaofan and Hutuo Groups is determined. Zircon grains liberated from a tuff layer (metamorphosed to sericite-quartz schist) in the upper part of the Mohe Formation (the second of the three formations of the Gaofan Group) yield a weighted average 207Pb/206Pb age of 2186 ± 8 Ma (n = 7, MSWD = 1.3), representing time of deposition. This age and the detrital zircon U-Pb ages of the basal feldspar quartzite (meta-siltstone), as well as the initial deposition age of the unconformably overlying Hutuo Group, confine the deposition age of the Gaofan Group to 2350-2150 Ma. This result negates the Gaofan Group as one subgroup of the 2560-2510 Ma Wutai greenstone belt. Zircons from the Banlaoyao mafic sill (meta-diabase) that intruded the Dongye Subgroup of the Hutuo Group yield an upper intercept U-Pb age of 2057 ± 25 Ma (n = 14, MSWD = 1.3), representing time of crystallization. Considering the age of the basalt in the first formation of the Doucun Subgroup and the tuff in the first formation of the Dongye Subgroup, the deposition age of the Doucun and Dongye Subgroups of the Hutuo Group is confined to 2150-2090 Ma and 2090-2060 Ma, respectively. These age brackets, as well as the available carbon and nitrogen isotope data indicate that the Zhangxianbu Formation of the Gaofan Group possibly recorded the GOE; whereas the Mohe-Yaokouqian Formations of the Gaofan Group and the Doucun-Dongye Subgroups of the Hutuo Group recorded the subsequent Lomagundi-Jatuli Event (LJE). However, the Lomagundi-Jatuli carbon excursions are hardly distinguishable from the Gaofan Group and the Doucun Subgroup (Hutuo Group) as both units consist of little inorganic carbon but terrestrial clastic turbidites.

Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

PubMed

Rodriguez, J Alexis P; Kargel, Jeffrey S; Baker, Victor R; Gulick, Virginia C; Berman, Daniel C; Fairén, Alberto G; Linares, Rogelio; Zarroca, Mario; Yan, Jianguo; Miyamoto, Hideaki; Glines, Natalie

2015-09-08

Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System's most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet's upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected]. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

PubMed Central

Rodriguez, J. Alexis P.; Kargel, Jeffrey S.; Baker, Victor R.; Gulick, Virginia C.; Berman, Daniel C.; Fairén, Alberto G.; Linares, Rogelio; Zarroca, Mario; Yan, Jianguo; Miyamoto, Hideaki; Glines, Natalie

2015-01-01

Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System’s most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet’s upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform Boundary. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which was then completely submerged under a primordial northern plains ocean. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation. PMID:26346067

Hydrogeology and water quality of the shallow aquifer system at the Explosive Experimental Area, Naval Surface Warfare Center, Dahlgren Site, Dahlgren, Virginia

USGS Publications Warehouse

Bell, C.F.

1996-01-01

In October 1993, the U.S. Geological Survey began a study to characterize the hydrogeology of the shallow aquifer system at the Explosive Experimental Area, Naval Surface Warfare Center, Dahlgren Site, Dahlgren, Virginia, which is located on the Potomac River in the Coastal Plain Physiographic Province. The study provides a description of the hydrogeologic units, directions of ground-water flow, and back-ground water quality in the study area to a depth of about 100 feet. Lithologic, geophysical, and hydrologic data were collected from 28 wells drilled for this study, from 3 existing wells, and from outcrops. The shallow aquifer system at the Explosive Experimental Area consists of two fining-upward sequences of Pleistocene fluvial-estuarine deposits that overlie Paleocene-Eocene marine deposits of the Nanjemoy-Marlboro confining unit. The surficial hydrogeologic unit is the Columbia aquifer. Horizontal linear flow of water in this aquifer generally responds to the surface topography, discharging to tidal creeks, marshes, and the Potomac River, and rates of flow in this aquifer range from 0.003 to 0.70 foot per day. The Columbia aquifer unconformably overlies the upper confining unit 12-an organic-rich clay that is 0 to 55 feet thick. The upper confining unit conformably overlies the upper confined aquifer, a 0- to 35-feet thick unit that consists of interbedded fine-grained to medium-grained sands and clay. The upper confined aquifer probably receives most of its recharge from the adjacent and underlying Nanjemoy-Marlboro confining unit. Water in the upper confined aquifer generally flows eastward, northward, and northeastward at about 0.03 foot per day toward the Potomac River and Machodoc Creek. The Nanjemoy-Marlboro confining unit consists of glauconitic, fossiliferous silty fine-grained sands of the Nanjemoy Formation. Where the upper confined system is absent, the Nanjemoy-Marlboro confining unit is directly overlain by the Columbia aquifer. In some parts of the Explosive Experimental Area, horizontal hydraulic conductivities of the Nanjemoy-Marlboro confining unit and the Columbia aquifer are similar (from 10-4 to 10-2 foot per day), and these units effectively combine to form a thick (greater than 50 feet) aquifer. The background water quality of the shallow aquifer system is characteristic of ground waters in the Virginia Coastal Plain Physiographic Province. Water in the Columbia aquifer is a mixed ionic type, has a median pH of 5.9, and a median total dissolved solids of 106 milligrams per liter. Water in the upper confined aquifer and Nanjemoy-Marlboro confining unit is a sodium- calcium-bicarbonate type, and generally has higher pH, dissolved solids, and alkalinity than water in the Columbia aquifer. Water in the upper confined aquifer and some parts of the Columbia aquifer is anoxic, and it has high concentrations of dissolved iron, manganese, and sulfide.

Hydrogeology, water quality, and saltwater intrusion in the Upper Floridan Aquifer in the offshore area near Hilton Head Island, South Carolina, and Tybee Island, Georgia, 1999-2002

USGS Publications Warehouse

Falls, W. Fred; Ransom, Camille; Landmeyer, James E.; Reuber, Eric J.; Edwards, Lucy E.

2005-01-01

To assess the hydrogeology, water quality, and the potential for saltwater intrusion in the offshore Upper Floridan aquifer, a scientific investigation was conducted near Tybee Island, Georgia, and Hilton Head Island, South Carolina. Four temporary wells were drilled at 7, 8, 10, and 15 miles to the northeast of Tybee Island, and one temporary well was drilled in Calibogue Sound west of Hilton Head Island. The Upper Floridan aquifer at the offshore and Calibogue sites includes the unconsolidated calcareous quartz sand, calcareous quartz sandstone, and sandy limestone of the Oligocene Lazaretto Creek and Tiger Leap Formations, and the limestone of the late Eocene Ocala Limestone and middle Avon Park Formation. At the 7-, 10-, and 15-mile sites, the upper confining unit between the Upper Floridan and surficial aquifers correlates to the Miocene Marks Head Formation. Paleochannel incisions have completely removed the upper confining unit at the Calibogue site and all but a 0.8-foot-thick interval of the confining unit at the 8-mile site, raising concern about the potential for saltwater intrusion through the paleochannel-fill sediments at these two sites. The paleochannel incisions at the Calibogue and 8-mile sites are filled with fine- and coarse-grained sediments, respectively. The hydrogeologic setting and the vertical hydraulic gradients at the 7- and 10-mile sites favored the absence of saltwater intrusion during predevelopment. After decades of onshore water use in Georgia and South Carolina, the 0-foot contour in the regional cone of depression of the Upper Floridan aquifer is estimated to have been at the general location of the 7- and 10-mile sites by the mid-1950s and at or past the 15-mile site by the 1980s. The upward vertical hydraulic gradient reversed, but the presence of more than 17 feet of upper confining unit impeded the downward movement of saltwater from the surficial aquifer to the Upper Floridan aquifer at the 7- and 10-mile sites. At the 10-mile site, the chloride concentration in the Upper Floridan borehole-water sample and the pore-water samples from the Oligocene and Eocene strata support the conclusion of no noticeable modern saltwater intrusion in the Upper Floridan aquifer. The chloride concentration of 370 milligrams per liter in the borehole-water sample at the 7-mile site from the Upper Floridan aquifer at 78 to 135 feet below North American Vertical Datum of 1988 is considerably higher than the chloride concentration of 25 milligrams per liter measured at the 10-mile site. The higher concentration probably is the result of downward leakage of saltwater through the confining unit at the 7-mile site or could reflect downward leakage of saltwater through an even thinner layer of the upper confining unit beneath the paleochannel to the northeast and lateral movement (encroachment) from the paleochannel to the 7-mile site. Carbon-14 concentrations at both sites, however, are low and indicate that most of the water is relict fresh ground water. The hydrogeology at the 15-mile site includes 17 feet of the upper confining unit. The chloride concentration in the Upper Floridan aquifer is 6,800 milligrams per liter. The setting for the Upper Floridan aquifer beneath the 15-mile site is interpreted as a transitional mixing zone between relict freshwater and relict saltwater. At the Calibogue site, 35 feet of fine-grained paleochannel-fill sediments overlies the Oligocene strata of the Upper Floridan aquifer. The vertical hydraulic conductivity of the paleochannel fill at this site is similar to the upper confining unit and effectively replaces the missing upper confining unit. Chloride concentrations and low carbon-14 and tritium concentrations in borehole water from the Upper Floridan aquifer, and low chloride concentrations in pore water from the upper confining unit indicate relict freshwater confined in the Upper Floridan aquifer at the Calibogue site. The coarse-grained paleochannel-f

Lower Miocene stratigraphy of the Gebel Shabrawet area, north Eastern desert Egypt

NASA Astrophysics Data System (ADS)

Abdelghany, Osman

2002-05-01

The Lower Miocene carbonate/siliciclastic sequence of the Shabrawet area, comprises a complex alternation of autochthonous and allogenic sediments. The sequence can be subdivided into two lithostratigraphic units. The lower unit (unit I) is equivalent to the Gharra Formation. It is mainly clastic and composed of sandstones, siltstones and shales with minor limestone intercalations. These sediments are rich in Clypeaster spp., Scutella spp., Miogypsina intermedia, Operculina complanata, and smaller foraminifera. The upper unit (unit II) was considered by previous workers as being equivalent to the Marmarica Formation. It consists mainly of non-clastic rocks, dominated by sandy and chalky limestones rich in larger foraminifera (miogypsinids and nummulitids). This unit is topped by a highly fossiliferous ( Heterostegina, Operculina and Planostegina) sandy limestone. The present study places both units in the Gharra Formation and reports for the first time M. intermedia from the Miocene sequence of the Shabrawet area.

The coal-forming plants of the upper part of the Lower Cretaceous Starosuchan Formation (Partizansk Basin, South Primorye region)

NASA Astrophysics Data System (ADS)

Bugdaeva, E. V.; Markevich, V. S.; Volynets, E. B.

2014-05-01

The plant remains and palynological assemblages are studied in detail in the section of the coal-bearing upper part of the Aptian Starosuchan Formation near the village of Molchanovka (Partizansk Basin, South Primorye region). On the basis of the light and electron microscopic study of the disperse cuticles, it was established that the coals are mostly composed of remains of taxodialean Elatides asiatica (Yok.) Krassil., subordinate Miroviaceae, rare ginkgoalean Pseudotorellia sp., and bennettite Nilssoniopteris rithidorachis (Krysht.) Krassil. The spores Gleicheniidites and pollen Taxodiaceaepollenites are dominant in the palynospectrum of the coal interlayer. It was found that dominant taxodialeans and gleicheniaceous ferns with less abundant Miroviaceae, ginkgoaleans, and rare bennettites occurred in the Aptian swamp communities of the Partizansk basin. Shoots and leaves of Elatides asiatica, fronds of Birisia onychioides (Vassil. et K.-M.) Samyl., are dominant in the burials of plants from the clastic rocks. The fragments of leaves of Nilssoniopteris, scale-leaved conifers, and Ginkgo ex gr. adiantoides are rare. The disperse cuticle of these layers mostly includes Pseudotorellia sp.; however, its remains in burials were not found. The spores Laevigatosporites are dominant in the palynospectra from the clastic interlayers. Ginkgocycadophytus and taxa close to Pinaceae are plentiful among the pollen of gymnosperms.

Paleoecology of the Devonian-Mississippian black-shale sequence in eastern Kentucky with an atlas of some common fossils

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

Barron, L.S.; Ettensohn, F.R.

The Devonian-Mississippian black-shale sequence of eastern North America is a distinctive stratigraphic interval generally characterized by low clastic influx, high organic production in the water column, anaerobic bottom conditions, and the relative absence of fossil evidence for biologic activity. The laminated black shales which constitute most of the black-shale sequence are broken by two major sequences of interbedded greenish-gray, clayey shales which contain bioturbation and pyritized micromorph invertebrates. The black shales contain abundant evidence of life from upper parts of the water column such as fish fossils, conodonts, algae and other phytoplankton; however, there is a lack of evidence ofmore » benthic life. The rare brachiopods, crinoids, and molluscs that occur in the black shales were probably epiplanktic. A significant physical distinction between the environment in which the black sediments were deposited and that in which the greenish-gray sediments were deposited was the level of dissolved oxygen. The laminated black shales point to anaerobic conditions and the bioturbated greenish-gray shales suggest dysaerobic to marginally aerobic-dysaerobic conditions. A paleoenvironmental model in which quasi-estuarine circulation compliments and enhances the effect of a stratified water column can account for both depletion of dissolved oxygen in the bottom environments and the absence of oxygen replenishment during black-shale deposition. Periods of abundant clastic influx from fluvial environments to the east probably account for the abundance of clays in the greenish-gray shale as well as the small amounts of oxygen necessary to support the depauparate, opportunistic, benthic faunas found there. These pulses of greenish-gray clastics were short-lived and eventually were replaced by anaerobic conditions and low rates of clastic sedimentation which characterized most of black-shale deposition.« less

Fluvial channel-belts, floodbasins, and aeolian ergs in the Precambrian Meall Dearg Formation (Torridonian of Scotland): Inferring climate regimes from pre-vegetation clastic rock records

NASA Astrophysics Data System (ADS)

Lebeau, Lorraine E.; Ielpi, Alessandro

2017-07-01

The interpretation of climate regimes from facies analysis of Precambrian clastic rocks has been challenging thus far, hindering full reconstructions of landscape dynamics in pre-vegetation environments. Yet, comparisons between different and co-active sedimentary realms, including fluvial-channelised, floodplain, and aeolian hold the potential to shed further light on this thematic. This research discusses a fluvial-aeolian record from the 1.2 Ga Meall Dearg Formation, part of the classic Torridonian succession of Scotland. Tentatively considered to date as a braided-fluvial deposit, this unit is here reappraised as the record of fluvial channel-belts, floodbasins, and aeolian ergs. Fluvial deposits with abundant transitional- to upper-flow regime structures (mostly cross-beds with tangential sets and plane/antidunal beds) and simple, low-relief sediment bars indicate a low-sinuosity, ephemeral style. Floodbasin deposits consist of plane and cross-beds ubiquitously bounded by symmetrical ripples, and rare sediment bars related to the progradation of splay complexes in temporary flooded depressions. Aeolian deposits occur nearby basement topography, and are dominated by large-scale, pin-stripe laminated cross-beds, indicative of intermountain ergs. Neither ephemeral-fluvial nor intermountain aeolian systems can be considered as reliable indicators of local climate, since their sedimentary style is respectively controlled by catchment size and shape, and basin topography relative to groundwater tables. Contrarily, the occurrence of purely clastic - rather than carbonate or evaporitic - floodplain strata can be more confidently related to humid regimes. In brief, this study provides new insight into an overlooked portion of the Torridonian succession of Scotland, and discusses climate inferences for Precambrian clastic terrestrial rocks.

Subglacial Depositional Processes in the Port Askaig Formation (Neoproterozoic) of Ireland

NASA Astrophysics Data System (ADS)

Knight, J.

2004-12-01

The Port Askaig Formation was deposited during the Vendian glaciation (c. 650 Ma) and is a range of tillites that outcrop discontinuously from Banffshire (Scotland) to Connemara (Ireland). Sedimentary structures commonly observed include dropstones and sediment drapes, interpreted as deposition from a floating glacial ice shelf in a shallow marginal sea. Other structures, such as intersecting clastic dikes, have been interpreted as evidence for subaerial exposure of the tillite surface. Exposures of the Port Askaig Formation were examined at its Irish type area at Kiltyfanned Lough, County Donegal. Here, homogeneous sandy beds with internal planar bedding structures are separated by laminated fine sand beds which have erosional upper surfaces. The laminated beds are clast-free and individual laminae are laterally continuous and undisturbed. Larger clasts lie bed-parallel and are draped by overlying beds. Occasionally drapes are asymmetric with a thickened sediment prow, suggestive of flow direction. The clastic dikes are polygonal in plan view, may be isolated or interconnected, and are often arranged in parallel sheets which pinch out laterally. Internally, the clastic dikes are infilled with coarse sand to gravel. Infills are often aligned parallel to dike margins. The presence of draped and deformed sediments suggest a subglacial environment with free water availability. The flat-lying morphology of clasts also favours a subglacial rather than a full marine environment. The morphology and disposition of clastic dikes is interpreted as due to subglacial hydrofracturing of a till sheet and upward passage of sediment-charged water through the fracture zone, which is known from late Pleistocene and Precambrian tillites elsewhere. Variations in water availability can be reconciled by a sub-ice shelf depositional model with spatial and temporal changes in tidally-induced ice-bed coupling.

Stratigraphic and hydrogeologic framework of the Alabama Coastal Plain

USGS Publications Warehouse

Davis, M.E.

1988-01-01

Tertiary and Cretaceous sand aquifers of the Southeastern United States Coastal Plain comprise a major multlstate aquifer system informally defined as the Southeastern Coastal Plain aquifer system, which is being studied as part of the U.S. Geological Survey's Regional Aquifer System Analysis (RASA) program. The major objectives of each RASA study are to identify, delineate, and map the distribution of permeable clastlc rock, to examine the pattern of ground-water flow within the regional aquifers, and to develop digital computer simulations to understand the flow system. The Coastal Plain aquifers in Alabama are being studied as a part of this system. This report describes the stratlgraphlc framework of the Cretaceous, Tertiary, and Quaternary Systems in Alabama to aid in delineating aquifers and confining units within the thick sequence of sediments that comprises the Southeastern Coastal Plain aquifer system in the State. Stratigraphlc units of Cretaceous and Tertiary age that make up most of the aquifer system in the Coastal Plain of Alabama consist of clastlc deposits of Early Cretaceous age; the Coker and Gordo Formations of the Tuscaloosa Group, Eutaw Formation, and Selma Group of Late Cretaceous age; and the Midway, Wilcox, and Clalborne Groups of Tertiary age. However, stratigraphlc units of late Eocene to Holocene age partially overlie and are hydraulically connected to clastic deposits in southern Alabama. These upper carbonate and clastlc stratlgraphic units also are part of the adjoining Florldan and Gulf Coastal Lowlands aquifer systems. The Coastal Plain aquifer system is underlain by pre-Cretaceous rocks consisting of low-permeabillty sedimentary rocks of Paleozolc, Triassic, and Jurassic age, and a complex of metamorphic and igneous rocks of Precambrian and Paleozolc age similar to those found near the surface in the Piedmont physiographic province. Twelve hydrogeologlc units in the Alabama Coastal Plain are defined--slx aquifers and six confining units. Aquifers of the Coastal Plain aquifer system are composed of fine to coarse sand, gravel, and limestone; confining beds are composed of clay, shale, chalk, marl, and metamorphic and igneous rocks.

Magnetotelluric Data, Mid Valley, Nevada Test Site, Nevada

USGS Publications Warehouse

Williams, Jackie M.; Wallin, Erin L.; Rodriguez, Brian D.; Lindsey, Charles R.; Sampson, Jay A.

2007-01-01

Introduction The United States Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) at their Nevada Site Office (NSO) are addressing ground-water contamination resulting from historical underground nuclear testing through the Environmental Management (EM) program and, in particular, the Underground Test Area (UGTA) project. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow. Ground-water modelers would like to know more about the hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Rainier Mesa/Shoshone Mountain Corrective Action Unit (CAU). During 2003, the U.S. Geological Survey (USGS), in cooperation with the DOE and NNSA-NSO, collected and processed data at the Nevada Test Site in and near Yucca Flat (YF) to help define the character, thickness, and lateral extent of the pre-Tertiary confining units. We collected 51 magnetotelluric (MT) and audio-magnetotelluric (AMT), stations for that research. In early 2005 we extended that research with 26 additional MT data stations, located on and near Rainier Mesa and Shoshone Mountain (RM-SM). The new stations extended the area of the hydrogeologic study previously conducted in Yucca Flat. This work was done to help refine what is known about the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal was to define the upper clastic confining unit (UCCU). The UCCU is comprised of late Devonian to Mississippian siliciclastic rocks assigned to the Eleana Formation and Chainman Shale. The UCCU underlies the Yucca Flat area and extends westward towards Shoshone Mountain, southward to Buckboard Mesa, and northward to Rainier Mesa. Late in 2005 we collected another 14 MT stations in Mid Valley and in northern Yucca Flat basin. That work was done to better determine the extent and thickness of the UCCU near the southeastern RM-SM CAU boundary with the southwestern YF CAU, and also in the northern YF CAU. The purpose of this report is to release the MT data at those 14 stations. No interpretation of the data is included here.

The effect of a confining unit on the geochemical evolution of ground water in the Upper Floridan aquifer system

USGS Publications Warehouse

Wicks, C.M.; Herman, J.S.

1994-01-01

In west-central Florida, sections of the Upper Floridan aquifer system range in character from confined to leaky to unconfined. The confining unit is the Hawthorn Formation, a clay-rich sequence. The presence or absence of the Hawthorn Formation affects the geochemical evolution of the ground water in the Upper Floridan aquifer system. Mass-balance and mass-transfer models suggest that, in unconfined areas, the geochemical reactions are dolomite dissolution, ion exchange (Mg for Na, K), sulfate reduction, calcite dissolution, and CO2 exchange. In the areas in which the Hawthorn Formation is leaky, the evolution of the ground water is accounted for by ion exchange, sulfate reduction, calcite dissolution, and CO2 exchange. In the confined areas, no ion exchange and only limited sulfate reduction occur, and the chemical character of the ground water is consistent with dolomite and gypsum dissolution, calcite precipitation, and CO2 ingassing. The Hawthorn Formation acts both as a physical barrier to the transport of CO2 and organic matter and as a source of ion-exchange sites, but the carbonate-mineral reactions are largely unaffected by the extent of confinement of the Upper Floridan aquifer. ?? 1994.

Geomorphic and Aqueous Chemistry of a Portion of the Upper Rio Tinto System, Spain

NASA Technical Reports Server (NTRS)

Osburn, M. R.; Fernandez-Remolar, D. C.; Arvidson, R. E.; Morris, R. V.; Ming, D.; Prieto-Ballesteros, O.; Amils, R.; Stein, T. C.; Heil-Chapdelaine, V.; Friedlander, L. R.;

Mesozoic evolution of the Amu Darya basin

NASA Astrophysics Data System (ADS)

Brunet, Marie-Françoise; Ershov, Andrey; Korotaev, Maxim; Mordvintsev, Dmitriy; Barrier, Eric; Sidorova, Irina

2014-05-01

This study, granted by the Darius Programme, aims at proposing a model of tectono-stratigraphic evolution of the Amu Darya basin since the Late Palaeozoic and to understand the relationship with the nearby basins. The Amu Darya basin, as its close eastern neighbour, the Afghan-Tajik basin, lies on the Turan platform, after the closure of the Turkestan Ocean during the Late Paleozoic. These two basins, spread on mainly lowlands of Turkmenistan, southwest Uzbekistan, Tajikistan, and northern Afghanistan, are separated from one another by the South-Western Gissar meganticline, where series of the northern Amu Darya margin are outcropping. The evolution is closely controlled by several periods of crustal thinning (post-collision rifting and back-arc extension), with some marine incursions, coming in between accretions of continental blocks and collisions that succeeded from the Late Triassic-Early Jurassic (Eo-Cimmerian orogeny) to the Cenozoic times. These orogenies controlled the deposition of thick clastics sequences, and the collision of the Indian Plate with Eurasia strongly deformed the sedimentary cover of the Afghan-Tajik basin. The more than 7 km thick Meso-Cenozoic sedimentary succession of the Amu Darya basin, lies on a complex system of rifts and blocks. Their orientation and age (late Permian, Triassic?) are not well known because of deep burial. The north-eastern margin, with the Bukhara (upper margin) and Chardzhou steps, is NW oriented, parallel to the Paleozoic Turkestan suture. The orientation bends to W-E, in the part of the Gissar situated to the North of the Afghan-Tajik basin. This EW trending orientation prevails also in the south(-eastern) margin of the basin (series of North Afghanistan highs) and in the Murgab depression, the south-eastern deepest portion of the Amu Darya basin. It is in this area and in the eastern part of the Amu Darya basin that the Jurassic as well as the lower Cretaceous sediments are the thickest. The south-western part of the basin is occupied by the Pre-Kopet Dagh Cenozoic foreland basin NW oriented, possibly underlain by an earlier extensional trough. The main elements of the sedimentary pile, which can be partly observed in the South-Western Gissar are: Lower to Middle Jurassic continental to paralic clastic rocks; upper Middle to Upper Jurassic marine carbonate then thick Tithonian evaporite rocks, sealing the reservoirs in the Jurassic carbonates; continental Neocomian clastic rocks and red beds, Aptian to Paleogene marine carbonate and clastic rocks. To reconstruct the geodynamic evolution of the Amu Darya Basin, we analysed the subsidence by backstripping of some wells/pseudo-wells and of three cross-sections with some examples of thermal modelling on the periods of maturation of the potential source rocks. The crustal thinning events take place in the Permo-Triassic? (depending on the age of the rifts underlying the basin), in Early-Middle Jurassic and during the Early Cretaceous, resulting in increases of the tectonic subsidence rates.

Litho-kinematic facies model for large landslide deposits in arid settings

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

Yarnold, J.C.; Lombard, J.P.

1989-04-01

Reconnaissance field studies of six large landslide deposits in the S. Basin and Range suggest that a set of characteristic features is common to the deposits of large landslides in an arid setting. These include a coarse boulder cap, an upper massive zone, a lower disrupted zone, and a mixed zone overlying disturbed substrate. The upper massive zone is dominated by crackel breccia. This grades downward into a lower disrupted zone composed of a more matrix-rich breccia that is internally sheared, intruded by clastic dikes, and often contains a cataclasite layer at its base. An underlying discontinuous mixed zone ismore » composed of material from the overlying breccia mixed with material entrained from the underlying substrate. Bedding in the substrate sometimes displays folding and contortion that die out downward. The authors work suggests a spatial zonation of these characteristic features within many landslide deposits. In general, clastic dikes, the basal cataclasite, and folding in the substrate are observed mainly in distal parts of landslides. In most cases, total thickness, thickness of the basal disturbed and mixed zones, and the degree of internal shearing increase distally, whereas maximum clast size commonly decreases distally. Zonation of these features is interpreted to result from kinematics of emplacement that cause generally increased deformation in the distal regions of the landslide.« less

Thoughts Regarding the Dimensions of Faults at Rainier and Aqueduct Mesas, Nye County, Nevada, Based on Surface and Underground Mapping

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

Drellack, S.L.; Prothro, L.B.; Townsend, M.J.

2011-02-01

The geologic setting and history, along with observations through 50 years of detailed geologic field work, show that large-displacement (i.e., greater than 30 meters of displacement) syn- to post-volcanic faults are rare in the Rainier Mesa area. Faults observed in tunnels and drill holes are mostly tight, with small displacements (most less than 1.5 meters) and small associated damage zones. Faults are much more abundant in the zeolitized tuffs than in the overlying vitric tuffs, and there is little evidence that faults extend downward from the tuff section through the argillic paleocolluvium into pre-Tertiary rocks. The differences in geomechanical characteristicsmore » of the various tuff lithologies at Rainier Mesa suggest that most faults on Rainer Mesa are limited to the zeolitic units sandwiched between the overlying vitric bedded tuffs and the underlying pre-Tertiary units (lower carbonate aquifer–3, lower clastic confining unit–1, and Mesozoic granite confining unit).« less

Summary of the hydrology of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama

USGS Publications Warehouse

Johnston, Richard H.; Bush, Peter W.

1988-01-01

The Floridan aquifer system is one of the major sources of ground-water supplies in the United States. This highly productive aquifer system underlies all of Florida, southern Georgia, and small parts of adjoining Alabama and South Carolina, for a total area of about 100,000 square miles. About 3 billion gallons of water per day is withdrawn from the aquifer for all uses, and, in many areas, the Floridan is the sole source of freshwater. The aquifer system is a sequence of hydraulically connected carbonate rocks (principally limestone and some dolomite) that generally range in age from Late Paleocene to Early Miocene. The rocks vary in thickness from a featheredge where they crop out to more than 3,500 ft where the aquifer is deeply buried. The aquifer system generally consists of an upper aquifer and a lower aquifer, separated by a less permeable confining unit of highly variable properties. In parts of north Florida and southwest Georgia, there is little permeability contrast within the aquifer system. Thus in these areas the Floridan is effectively one continuous aquifer. The upper and lower aquifers are defined on the basis of permeability, and their boundaries locally do not coincide with those for either time-stratigraphic or rock-stratigraphic units. Low-permeability clastic rocks overlie much of the Floridan aquifer system. The lithology, thickness, and integrity of these low-permeability rocks have a controlling effect on the development of permeability and ground-water flow in the Floridan locally. The Floridan aquifer system derives its permeability from openings that vary from fossil hashes and networks of many solution-widened joints to large cavernous openings in karst areas. Diffuse flow pre-dominates where the small openings occur, whereas conduit flow may occur where there are large cavernous openings. For the Upper Floridan aquifer, transmissivities are highest (greater than 1,000,000 ft squared per day) in the unconfined karst areas of central and northern Florida. Lowest transmissivities (less than 50,000 ft squared per day) occur in the Florida panhandle and southernmost Florida, where the Upper Floridan aquifer is confined by thick clay sections. The hydraulic properties of the Lower Floridan aquifer are not well known; however, this unit also contains intervals of very high transmissivity that have been attributed to paleokarst development. The dominant feature of the Floridan flow system, both before and after ground-water development, is Upper Floridan aquifer springs, nearly all of which occur in unconfined and semiconfined parts of the aquifer in Florida. Before ground-water development, spring flow and point discharge to surface-water bodies was about 88 percent of the estimated 21,500 cubic ft per second total discharge. Current discharge (early 1980's) is about 24,100 cubic ft per second, 75 percent of which is spring flow and discharge to surface-water bodies, 17 percent is withdrawal from wells, and 8 percent is diffuse upward leakage. Pumpage has been and continues to be supplied primarily by the diversion of natural outflow from the aquifer system and by induced recharge rather than by loss of water from aquifer storage. The approximately 3 billion gallons per day pumped from the Floridan aquifer system has resulted in long-term regional water-level declines of more than 10 ft in three broad areas of the flow system: (1) coastal Georgia and adjacent South Carolina and northeast Florida, (2) west-central Florida, and (3) the Florida panhandle. Saltwater has encroached as a result of pumping in a few coastal areas. In general, the water chemistry in the Upper Floridan is related to flow and proximity to the freshwater-saltwater interface. In the unconfined or semiconfined areas where flow is vigorous, dissolved-solids concentrations are low (less than 250 milligrams per liter). Where the system is more tightly confined, flow is more sluggish and concentrations are higher (grea

Emplacement model of obsidian-rhyolite magma deduced from complete internal section of the Akaishiyama lava, Shirataki, northern Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Wada, K.; Sano, K.

2016-12-01

Simultaneously explosive and effusive eruptions of silicic magmas has shed light on the vesiculation and outgassing history of ascending magmas in the conduit and emplacement model of obsidian-rhyolite lavas (Castro et al., 2014; Shipper et al, 2013). As well as the knowledge of newly erupted products such as 2008-2009 Chaitén and 2011-2012 Cordón Caule eruptions, field and micro-textural evidences of well-exposed internal structure of obsidian-rhyolite lava leads to reveal eruption processes of silicic magmas. The Shirataki monogenetic volcano field, 2.2 million year age, northern Hokkaido, Japan, contains many outcrops of obsidian and vesiculated rhyolite zones (SiO2=76.7-77.4 wt.%). Among their outcrops, Akaishiyama lava shows good exposures of internal sections from the top to the bottom along the Kyukasawa valley with thickness of about 190 meters, showing the symmetrical structure comprising a upper clastic zone (UCZ; 5m thick), an upper dense obsidian zone (UDO; 15m), an upper banded obsidian zone (UBO; 70-80m), a central rhyolite zone (CR; 65m), a lower banded obsidian zone (LBO; 15m), a lower dense obsidian zone (LDO; 20m), and a lower clastic zone (LCZ; 3m). The upper banded obsidian zone is characterized by existence of spherulite concentration layers with tuffisite veins and rhyolite enclaves. Spherulites consisting of albite, cristobalaite and obsidian glass, are clustered in the dense obsidian. Tuffisite veins show brecciated obsidians in tuffaceous matrix, showing an outgassing path during the emplacement of obsidian lava. Perpendicular dip of spherulite parallel rows indicates the banded zone itself was the domain of vent area. From the observation of these occurrences in the internal section and rock texture, we show the qualitative formation model of Shirataki obsidian-rhyolite lava.

A conceptual review of regional-scale controls on the composition of clastic sediment and the co-evolution of continental blocks and their sedimentary cover.

PubMed

Cox, R; Lowe, D R

1995-01-02

Both sediment recycling and first-cycle input influence the composition of clastic material in sedimentary systems. This paper examines conceptually the roles played by these processes in governing the composition of clastic sediment on a regional scale by outlining the expected effects on sediment composition of protracted sediment recycling and of continuous first-cycle input on a maturing continental block. Generally speaking, long-term recycling tends to enrich sediments in the most chemically and mechanically stable components: quartz in the sand and silt size fractions, and illite among the clay minerals. Sandstones trend towards pure quartz arenites, and mudrocks become more potassic and aluminous. The average grain size of clastic sediment decreases by a combination of progressive attrition of sand grains and ongoing breakdown of primary silicate minerals to finer-grained clay minerals and oxides. Sandstones derived by continuous first-cycle input from an evolving continental crustal source also become increasingly rich in quartz, but in addition become more feldspathic as the proportion of granitic material in the upper continental crust increases during crustal stabilization. Associated mudrocks also become richer in potassium and aluminum, but will have higher K2O/Al2O3 ratios than recycled muds. The average grain size of the sediment may increase with time as the proportion of sand-prone granitic source rocks increases at the expense of more mud-prone volcanic sources. In general, except in instances where chemical weathering is extreme, first-cycle sediments lack the compositional maturity of recycled detritus, and are characterized by the presence of a variety of primary silicate minerals. Sedimentary systems are not usually completely dominated by either recycling or first-cycle detritus. Generally, however, sedimentary systems associated with the earliest phases of formation and accretion of continental crust are characterized by first-cycle input from igneous and metamorphic rocks, whereas those associated with more mature cratons tend to be dominated by recycled sedimentary material.

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

NASA Astrophysics Data System (ADS)

Bordy, Emese M.; Catuneanu, Octavian

2001-08-01

The sedimentary rocks of the Karoo Supergroup in the Tuli Basin (South Africa) may be grouped in four stratigraphic units: the basal, middle and upper units, and the Clarens Formation. This paper presents the findings of the sedimentological investigation of the fluvial terrigenous clastic and chemical deposits of the upper unit. Evidence provided by primary sedimentary structures, palaeontological record, borehole data, palaeo-flow measurements and stratigraphic relations resulted in the palaeo-environmental reconstruction of the upper unit. The dominant facies assemblages are represented by sandstones and finer-grained sediments, which both can be interbedded with subordinate intraformational coarser facies. The facies assemblages of the upper unit are interpreted as deposits of a low-sinuosity, ephemeral stream system with calcretes and silcretes in the dinosaur-inhabited overbank area. During the deposition of the upper unit, the climate was semi-arid with sparse precipitation resulting in high-magnitude, low-frequency devastating flash floods. The current indicators of the palaeo-drainage system suggest flow direction from northwest to southeast, in a dominantly extensional tectonic setting. Based on sedimentologic and biostratigraphic evidence, the upper unit of the Tuli Basin correlates to the Elliot Formation in the main Karoo Basin to the south.

Magnetotelluric Data, Mid Valley, Nevada Test Site, Nevada.

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

Jackie M. Williams; Erin L. Wallin; Brian D. Rodriguez

2007-08-15

The United States Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) at their Nevada Site Office (NSO) are addressing ground-water contamination resulting from historical underground nuclear testing through the Environmental Management (EM) program and, in particular, the Underground Test Area (UGTA) project. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow. Ground-water modelers would like to know more about the hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Rainier Mesa/Shoshone Mountain Corrective Action Unit (CAU) (Bechtel Nevada, 2006).more » During 2003, the U.S. Geological Survey (USGS), in cooperation with the DOE and NNSA-NSO, collected and processed data at the Nevada Test Site in and near Yucca Flat (YF) to help define the character, thickness, and lateral extent of the pre-tertiary confining units. We collected 51 magnetotelluric (MT) and audio-magnetotelluric (AMT), stations for that research (Williams and others, 2005a, 2005b, 2005c, 2005d, 2005e, 2005f). In early 2005 we extended that research with 26 additional MT data stations (Williams and others, 2006), located on and near Rainier Mesa and Shoshone Mountain (RM-SM). The new stations extended the area of the hydrogeologic study previously conducted in Yucca Flat. This work was done to help refine what is known about the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal was to define the upper clastic confining unit (UCCU). The UCCU is comprised of late Devonian to Mississippian siliciclastic rocks assigned to the Eleana Formation and Chainman Shale. The UCCU underlies the Yucca Flat area and extends westward towards Shoshone Mountain, southward to Buckboard Mesa, and northward to Rainier Mesa. Late in 2005 we collected another 14 MT stations in Mid Valley and in northern Yucca Flat basin. That work was done to better determine the extent and thickness of the UCCU near the southeastern RM-SM CAU boundary with the southwestern YF CAU, and also in the northern YF CAU. The purpose of this report is to release the MT data at those 14 stations shown in figure 1. No interpretation of the data is included here.« less

Clastic sediment flux to tropical Andean lakes: records of glaciation and soil erosion

NASA Astrophysics Data System (ADS)

Rodbell, Donald T.; Seltzer, Geoffrey O.; Mark, Bryan G.; Smith, Jacqueline A.; Abbott, Mark B.

2008-08-01

We developed records of clastic sediment flux to 13 alpine lakes in Peru, Ecuador, and Bolivia, and compared these with independently dated records of regional glaciation. Our objectives are to determine whether a strong relationship exists between the extent of ice cover in the region and the rate of clastic sediment delivery to alpine lakes, and thus whether clastic sediment records serve as reliable proxies for glaciation during the late Pleistocene. We isolated the clastic component in lake sediment cores by removing the majority of the biogenic and authigenic components from the bulk sediment record, and we dated cores by a combination of radiocarbon and tephrochronology. In order to partially account for intra-basin differences in sediment focusing, bedrock erosivity, and sediment availability, we normalized each record to the weighted mean value of clastic sediment flux for each respective core. This enabled the stacking of all 13 lake records to produce a composite record that is generally representative of the tropical Andes. There is a striking similarity between the composite record of clastic sediment flux and the distribution of ˜100 cosmogenic radionuclide (CRN) exposure ages for erratics on moraine crests in the central Peruvian and northern Bolivian Andes. The extent of ice cover thus appears to be the primary variable controlling the delivery of clastic sediment to alpine lakes in the region, which bolsters the increasing use of clastic sediment flux as a proxy for the extent of ice cover in the region. The CRN moraine record and the stacked lake core composite record together indicate that the expansion of ice cover and concomitant increase in clastic sediment flux began at least 40 ka, and the local last glacial maximum (LLGM) culminated between 30 and 20 ka. A decline in clastic sediment flux that began ˜20 ka appears to mark the onset of deglaciation from the LLGM, at least one millennium prior to significant warming in high latitude regions. The interval between 20 and 18 ka was marked by near-Holocene levels of clastic sediment flux, and appears to have been an interval of much reduced ice extent. An abrupt increase in clastic sediment flux 18 ka heralded the onset of an interval of expanded ice cover that lasted until ˜14 ka. Clastic sediment flux declined thereafter to reach the lowest levels of the entire length of record during the early-middle Holocene. A middle Holocene climatic transition is apparent in nearly all records and likely reflects the onset of Neoglaciation and/or enhanced soil erosion in the tropical Andes.

Madbi Amran/Qishn total petroleum system of the Ma'Rib-Al Jawf/Shabwah, and Masila-Jeza basins, Yemen

USGS Publications Warehouse

Ahlbrandt, Thomas S.

2002-01-01

Since the first discovery of petroleum in Yemen in 1984, several recent advances have been made in the understanding of that countrys geologic history and petroleum systems. The total petroleum resource endowment for the combined petroleum provinces within Yemen, as estimated in the recent U.S. Geological Survey world assessment, ranks 51st in the world, exclusive of the United States, at 9.8 BBOE, which includes cumulative production and remaining reserves, as well as a mean estimate of undiscovered resources. Such undiscovered petroleum resources are about 2.7 billion barrels of oil, 17 trillion cubic feet (2.8 billion barrels of oil equivalent) of natural gas and 1 billion barrels of natural gas liquids. A single total petroleum system, the Jurassic Madbi Amran/Qishn, dominates petroleum generation and production; it was formed in response to a Late Jurassic rifting event related to the separation of the Arabian Peninsula from the Gondwana supercontinent. This rifting resulted in the development of two petroleum-bearing sedimentary basins: (1) the western MaRibAl Jawf / Shabwah basin, and (2) the eastern Masila-Jeza basin. In both basins, petroleum source rocks of the Jurassic (Kimmeridgian) Madbi Formation generated hydrocarbons during Late Cretaceous time that migrated, mostly vertically, into Jurassic and Cretaceous reservoirs. In the western MaRibAl Jawf / Shabwah basin, the petroleum system is largely confined to syn-rift deposits, with reservoirs ranging from deep-water turbidites to continental clastics buried beneath a thick Upper Jurassic (Tithonian) salt. The salt initially deformed in Early Cretaceous time, and continued halokinesis resulted in salt diapirism and associated salt withdrawal during extension. The eastern Masila-Jeza basin contained similar early syn-rift deposits but received less clastic sediment during the Jurassic; however, no salt formed because the basin remained open to ocean circulation in the Late Jurassic. Thus, Madbi Formation-sourced hydrocarbons migrated vertically into Lower Cretaceous estuarine, fluvial, and tidal sandstones of the Qishn Formation and were trapped by overlying impermeable carbonates of the same formation. Both basins were formed by extensional forces during Jurassic rifting; how-ever, another rifting event that formed the Red Sea and Gulf of Aden during Oligocene and Miocene time had a strong effect on the eastern Masila-Jeza basin. Recurrent movement of basement blocks, particularly during the Tertiary, rather than halokinesis, was critical to the formation of traps.

The Sirte Basin province of Libya; Sirte-Zelten total petroleum system

USGS Publications Warehouse

Ahlbrandt, Thomas S.

2001-01-01

The Sirte (Sirt) Basin province ranks 13th among the world?s petroleum provinces, having known reserves of 43.1 bil-lion barrels of oil equivalent (36.7 billion barrels of oil, 37.7 tril-lion cubic feet of gas, 0.1 billion barrels of natural gas liquids). It includes an area about the size of the Williston Basin of the north-ern United States and southern Canada (?490,000 square kilome-ters). The province contains one dominant total petroleum system, the Sirte-Zelten, based on geochemical data. The Upper Cretaceous Sirte Shale is the primary hydrocarbon source bed. Reservoirs range in rock type and age from fractured Precam-brian basement, clastic reservoirs in the Cambrian-Ordovician Gargaf sandstones, and Lower Cretaceous Nubian (Sarir) Sand-stone to Paleocene Zelten Formation and Eocene carbonates commonly in the form of bioherms. More than 23 large oil fields (>100 million barrels of oil equivalent) and 16 giant oil fields (>500 million barrels of oil equivalent) occur in the province. Abstract 1 Production from both clastic and carbonate onshore reservoirs is associated with well-defined horst blocks related to a triple junc-tion with three arms?an eastern Sarir arm, a northern Sirte arm, and a southwestern Tibesti arm. Stratigraphic traps in combina-tion with these horsts in the Sarir arm are shown as giant fields (for example, Messla and Sarir fields in the southeastern portion of the province). Significant potential is identified in areas marginal to the horsts, in the deeper grabens and in the offshore area. Four assessment units are defined in the Sirte Basin prov-ince, two reflecting established clastic and carbonate reservoir areas and two defined as hypothetical units. Of the latter, one is offshore in water depths greater than 200 meters, and the other is onshore where clastic units, mainly of Mesozoic age, may be res-ervoirs for laterally migrating hydrocarbons that were generated in the deep-graben areas. The Sirte Basin reflects significant rifting in the Early Cre-taceous and syn-rift sedimentary filling during Cretaceous through Eocene time, and post-rift deposition in the Oligocene and Miocene. Multiple reservoirs are charged largely by verti-cally migrating hydrocarbons along horst block faults from Upper Cretaceous source rocks that occupy structurally low posi-tions in the grabens. Evaporites in the middle Eocene, mostly post-rift, provide an excellent seal for the Sirte-Zelten hydrocarbon system. The offshore part of the Sirte Basin is complex, with subduction occurring to the northeast of the province boundary, which is drawn at the 2,000-meter isobath. Possible petroleum systems may be present in the deep offshore grabens on the Sirte Rise such as those involving Silurian and Eocene rocks; however, potential of these systems remains speculative and was not assessed.

Hydrogeology of the Canal Creek area, Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Oliveros, J.P.; Vroblesky, D.A.

1989-01-01

Geologic and borehole geophysical logs made at 77 sites show that the hydrogeologic framework of the study area consists of a sequence of unconsolidated sediments typical of the Coastal Plain of Maryland. Three aquifers and two confining units were delineated within the study area. From the surface down, they are: (1) the surficial aquifer; (2) the upper confining unit; (3) the Canal Creek aquifer; (4) the lower confining unit; and (5) the lower confined aquifer. The aquifer materials range from fine sand to coarse sand and gravel. Clay lenses were commonly found interfingered with the sand, isolating parts of the aquifers. All the units are continuous throughout the study area except for the upper confining unit, which crops out within the study area but is absent in updip outcrops. The unit also is absent within a Pleistocene paleochannel, where it has been eroded. The surficial and Canal Creek aquifers are hydraulically connected where the upper confining unit is absent, and a substantial amount of groundwater may flow between the two aquifers. Currently, no pumping stresses are known to affect the aquifers within the study area. Under current conditions, downward vertical hydraulic gradients prevail at topographic highs, and upward gradients typically prevail near surface-water bodies. Regionally, the direction of groundwater flow in the confined aquifers is to the east and southeast. Significant water level fluctuations correspond with seasonal variations in rainfall, and minor daily fluctuations reflect tidal cycles. (USGS)

Thrust-ridge paleodepositional model for the Upper Freeport coal bed and associated clastic facies, Upper Potomac coal field, Appalachian Basin, U.S.A.

USGS Publications Warehouse

Belt, Edward S.; Lyons, P.C.

1990-01-01

Two differential depositional sequences are recognized within a 37-m-thick lowermost section of the Conemaugh Group of Late Pennsylvanian (Westphalian D) age in the southern part of the Upper Potomac coal field (panhandle of Maryland and adjacent West Virginia). The first sequence is dominated by the Upper Freeport coal bed and zone (UF); the UF consists of a complex of interfingered thick coal beds and mudrocks. The UF underlies the entire 500 km2 study area (approximately 40 km in a NE-SW direction). The second sequence is dominated by medium- to coarse-grained sandstone and pebbly sandstone. They were deposited in channel belts that cut into and interfingered laterally with mudrock and fine- to medium-grained sandstone facies of floodbasin and crevasse-lobe origin. Thin lenticular coals occur in the second sequence. Nowhere in the study area does coarse-grained sandstone similar to the sandstone of the channel belts of the second sequence occur within the UF. However, 20 km north of the study area, coarse channel belts are found that are apparently synchronous with the UF (Lyons et al., 1984). The southeastern margin of the study are is bounded by the Allegheny Front. Between it and the North Mountain thrust (75 km to the southeast), lie at least eight other thrusts of unknown extent (Wilson, 1887). All these thrusts are oriented northwest; Devonian and older strata are exposed at the surface between the Allegheny Front and the North Mountain thrust. A blind-thrust ridge model is proposed to explain the relation of the two markedly depositional sequences to the thrusts that lie to the southeast of the Upper Potomac coal field. This model indicates that thrust ridges diverted coarse clastics from entering the swamp during a period when the thick Upper Freeport peat accumulated. Anticlinal thrust ridges and associated depressions are envisioned to have developed parallel to the Appalachian orogen during Middle and early Late Pennsylvanian time. A blind thrust developed from one of the outboard ridges, and it was thrust farther outboard ahead of the main body of the orogen. Sediment derived from the orogen was diverted into a sediment trap inboard of the ridge (Fig. 1). The ridge prevented sediment from entering the main peat-forming swamp. Sediment shed from the orogen accumulated in the sediment trap was carried out of the ends of the trap by steams that occupied the shear zone at the ends of the blind-thrust ridge (Fig. 1). Remnants of blind-thrust ridges occurs in the Sequatchie Valley thrust and the Pine Mountain thrust of the southern Appalachians. The extent, parallel to the orogen, of the thick areally extensive UF coal is related to the length of the blind-thrust ridge that, in turn, controlled the spacing of the river-derived coarse clastics that entered the main basin from the east. Further tectonism caused the thrust plane to emerge to the surface of the blind-thrust ridge. Peat accumulation was then terminated by the rapid erosion of the blind-thrust ridge and by the release of trapped sediment behind it. The peat was buried by sediments from streams from closely spaced channel belts] with intervening floodbasins. The model was implications for widespread peat (coal) deposits that developed in tropical regions, a few hundred kilometers inland from the sea during Pennsylvanian time (Belt and Lyons, 1989). ?? 1990.

Geochemistry and diagenesis of Miocene lacustrine siliceous sedimentary and pyroclastic rocks, Mytilinii basin, Samos Island, Greece

USGS Publications Warehouse

Stamatakis, M.G.; Hein, J.R.; Magganas, A.C.

1989-01-01

A Late Miocene non-marine stratigraphic sequence composed of limestone, opal-CT-bearing limestone, porcelanite, marlstone, diatomaceous marlstone, dolomite, and tuffite crops out on eastern Samos Island. This lacustrine sequence is subdivided into the Hora Beds and the underlying Pythagorion Formation. The Hora Beds is overlain by the clastic Mytilinii series which contains Turolian (Late Miocene) mammalian fossils. The lacustrine sequence contains volcanic glass and the silica polymorphs opal-A, opal-CT, and quartz. Volcanic glass predominantly occurs in tuffaceous rocks from the lower and upper parts of the lacustrine sequence. Opal-A (diatom frustules) is confined to layers in the upper part of the Hora Beds. Beds rich in opal-CT underlie those containing opal-A. The occurrence of opal-CT is extensive, encompassing the lower Hora Beds and the sedimentary rocks and tuffs of the Pythagorion Formation. A transition zone between the opal-A and opal-CT zones is identified by X-ray diffraction patterns that are intermediate between those of opal-CT and opal-A, perhaps due to a mixture of the two polymorphs. Diagenesis was not advanced enough for opal-CT to transform to quartz or for volcanic glass to transform to opal-C. Based on geochemical and mineralogical data, we suggest that the rate of diagenetic transformation of opal-A to opal-CT was mainly controlled by the chemistry of pore fluids. Pore fluids were characterized by high salinity, moderately high alkalinity, and high magnesium ion activity. These pore fluid characteristics are indicated by the presence of evaporitic salts (halite, sylvite, niter), high boron content in biogenic silica, and by dolomite in both the opal-A and opal-CT-bearing beds. The absence of authigenic K-feldspar, borosilicates, and zeolites also support these pore fluid characteristics. Additional factors that influenced the rate of silica diagenesis were host rock lithology and the relatively high heat flow in the Aegean region from Miocene to Holocene. ?? 1989.

Relationships between sedimentation, depositional environments, and coal quality: upper Potomac coalfield, West Virginia and Maryland

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

Jake, T.R.

1987-09-01

Evaluations were made of sedimentation patterns and depositional environments from approximately 450 core logs and 225 surface exposures in the Upper Potomac coalfield. The relationships between the clastic depositional facies and the distribution and quality of the Bakerstown and upper Freeport coals were also investigated. Data from 61 Bakerstown and 35 upper Freeport coal samples from selected cores indicate a change from uniform coal quality to highly variable coal quality when moving from related interchannel and bay-fill facies to channel, channel-fill, levee, and crevasse-splay facies. Areas of uniform coal quality range from 20-26% ash and 55-62% fixed carbon (weight percent,more » dry basis), whereas areas of highly variable coal quality range from 26-54% ash and 33-55% fixed carbon. The channel and related facies represent areas where increased fresh water was introduced into the topogenous swamp system, causing increased microbial degradation and the concentration of authigenic minerals within the peat material. These conditions, combined with the introduction of detrital minerals, resulted in areas of lower quality coal.« less

New Insights into Arctic Tectonics: Uranium-Lead, (Uranium-Thorium)/Helium, and Hafnium Isotopic Data from the Franklinian Basin, Canadian Arctic Islands

NASA Astrophysics Data System (ADS)

Anfinson, Owen Anthony

More than 2300 detrital zircon uranium-lead (U-Pb) ages, 32 176Hf/177Hf (eHf) isotopic values, 37 apatite helium (AHe) ages, and 72 zircon helium (ZHe) ages represent the first in-depth geochronologic and thermochronologic study of Franklinian Basin strata in the Canadian Arctic and provide new insight on >500 M.y. of geologic history along the northern Laurentian margin (modern orientation). Detrital zircon U-Pb age data demonstrate that the Franklinian Basin succession is composed of strata with three distinctly different provenance signatures. Neoproterozoic and Lower Cambrian formations contain detrital zircon populations consistent with derivation from Archean to Paleoproterozoic gneisses and granites of the west Greenland--northeast Canadian Shield. Lower Silurian to Middle Devonian strata are primarily derived from foreland basin strata of the East Greenland Caledonides (Caledonian orogen). Middle Devonian to Upper Devonian strata also contain detrital zircon populations interpreted as being primarily northerly derived from the continental landmass responsible for the Ellesmerian Orogen (often referred to as Crockerland). U-Pb age data from basal turbidites of the Middle to Upper Devonian clastic succession suggest Crockerland contributed sediment to the northern Laurentian margin by early-Middle Devonian time and that prior to the Ellesmerian Orogeny Crockerland had a comparable geologic history to the northern Baltica Craton. Detrital zircon U-Pb ages in Upper Devonian strata suggest Crockerland became the dominant source by the end of Franklinian Basin sedimentation. Mean eHf values from Paleozoic detrital zircon derived from Crockerland suggest the zircons were primarily formed in either an island arc or continental arc built on accreted oceanic crust setting. ZHe cooling ages from Middle and Upper Devonian strata were not buried deeper than 7 km since deposition and suggest Crockerland was partially exhumed during the Caledonian Orogen. AHe cooling ages are partially reset since deposition and experienced varying burial histories depending on stratigraphic and geographic location within the basin. AHe ages from Middle Devonian strata from the western margin of the basin indicate episodes of exhumation associated with clastic influxes of sediment into the Sverdrup Basin during the Late Jurassic-Early Cretaceous and Late Cretaceous.

Stratigraphy of lower to middle Paleozoic rocks of northern Nevada and the Antler orogeny

USGS Publications Warehouse

Ketner, Keith B.

2013-01-01

Commonly accepted concepts concerning the lower Paleozoic stratigraphy of northern Nevada are based on the assumption that the deep-water aspects of Ordovician to Devonian siliceous strata are due to their origin in a distant oceanic environment, and their presence where we find them is due to tectonic emplacement by the Roberts Mountains thrust. The concept adopted here is based on the assumption that their deep-water aspects are the result of sea-level rise in the Cambrian, and all of the Paleozoic strata in northern Nevada are indigenous to that area. The lower part of the Cambrian consists mainly of shallow-water cross-bedded sands derived from the craton. The upper part of the Cambrian, and part of the Ordovician, consists mainly of deep-water carbonate clastics carried by turbidity currents from the carbonate shelf in eastern Nevada, newly constructed as a result of sea-level rise. Ordovician to mid-Devonian strata are relatively deep-water siliceous deposits, which are the western facies assemblage. The basal contact of this assemblage on autochthonous Cambrian rocks is exposed in three mountain ranges and is clearly depositional in all three. The western facies assemblage can be divided into distinct stratigraphic units of regional extent. Many stratigraphic details can be explained simply by known changes in sea level. Upper Devonian to Mississippian strata are locally and westerly derived orogenic clastic beds deposited disconformably on the western facies assemblage. This disconformity, clearly exposed in 10 mountain ranges, indicates regional uplift and erosion of the western facies assemblage and absence of local deformation. The disconformity represents the Antler orogeny.

Transition from confined to phreatic conditions as the factor controlling salinization and change in redox state, Upper subaquifer of the Judea Group, Israel

NASA Astrophysics Data System (ADS)

Gavrieli, Ittai; Burg, Avi; Guttman, Joseph

2002-08-01

An increase in salinity and change from oxic to anoxic conditions are observed in the Upper subaquifer of the Judea Group in the Kefar Uriyya pumping field at the western foothills of the Judea Mountains, Israel. Hydrogeological data indicate that the change, which occurs over a distance of only a few kilometers, coincides with a transition from confined to phreatic conditions in the aquifer. The deterioration in the water quality is explained as a result of seepage of more saline, organic-rich water from above, into the phreatic "roofed" part of the aquifer. The latter is derived from the bituminous chalky rocks of the Mount Scopus Group, which confine the aquifer in its southeastern part. In this confined part, water in perched horizons within the Mount Scopus Group cannot leak down and flow westward while leaching organic matter and accumulating salts. However, upon reaching the transition area from confined to phreatic conditions, seepage to the Judea Upper subaquifer is possible, thereby allowing it to be defined as a leaky aquifer. The incoming organic matter consumes the dissolved oxygen and allows bacterial sulfate reduction. The latter accounts for the H2S in the aquifer, as indicated by sulfur isotopic analyses of coexisting sulfate and sulfide. Thus, from an aquifer management point of view, in order to maintain the high quality of the water in the confined southeastern part of the Kefar Uriyya field, care should be taken not to draw the confined-roofed transition area further east by over pumping.

Geology and physiography of the continental margin north of Alaska and implications for the origin of the Canada Basin

USGS Publications Warehouse

Grantz, Arthur; Eittreim, Stephen L.; Whitney, O.T.

1979-01-01

The continental margin north of Alaska is of Atlantic type. It began to form probably in Early Jurassic time but possibly in middle Early Cretaceous time, when the oceanic Canada Basin of the Arctic Ocean is thought to have opened by rifting about a pole of rotation near the Mackenzie Delta. Offsets of the rift along two fracture zones are thought to have divided the Alaskan margin into three sectors of contrasting structure and stratigraphy. In the Barter Island sector on the east and the Chukchi sector on the west the rift was closer to the present northern Alaska mainland than in the Barrow sector, which lies between them. In the Barter Island and Chukchi sectors the continental shelf is underlain by prisms of clastic sedimentary rocks that are inferred to include thick sections of Jurassic and Neocomian (lower Lower Cretaceous) strata of southern provenance. In the intervening Barrow sector the shelf is underlain by relatively thin sections of Jurassic and Neocomian strata derived from northern sources that now lie beneath the outer continental shelf. The rifted continental margin is overlain by a prograded prism of Albian (upper Lower Cretaceous) to Tertiary clastic sedimentary rocks that comprises the continental terrace of the western Beaufort and northern Chukchi Seas. On the south the prism is bounded by Barrow arch, which is a hingeline between the northward-tilted basement surface beneath the continental shelf of the western Beaufort Sea and the southward-tilted Arctic Platform of northern Alaska. The Arctic platform is overlain by shelf clastic and carbonate strata of Mississippian to Cretaceous age, and by Jurassic and Cretaceous clastic strata of the Colville foredeep. Both the Arctic platform and Colville foredeep sequences extend from northern Alaska beneath the northern Chukchi Sea. At Herald fault zone in the central Chukchi Sea they are overthrust by more strongly deformed Cretaceous to Paleozoic sedimentary rocks of Herald arch, which trends northwest from Cape Lisburne. Hope basin, an extensional intracontinental sedimentary basin of Tertiary age, underlies the Chukchi Sea south of Herald arch.

Petroleum geology of Cretaceous-Tertiary rift basins in Niger, Chad, and Central African Republic

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

Genik, G.J.

1993-08-01

This overview of the petroleum geology of rift basins in Niger, Chad, and Central African Republic (CAR) is based on exploration work by Exxon and partners in the years 1969-1991. The work included 50,000 km of modern reflection seismic, 53 exploration wells, 1,000,000 km[sup 2] of aeromagnetic coverage, and about 10,500 km of gravity profiles. The results outline ten Cretaceous and Tertiary rift basins, which constitute a major part of the West and Central African rift system (WCARS). The rift basins derive from a multiphased geologic history dating from the Pan-African (approximately 750-550 Ma) to the Holocene. WCARS in themore » study area is divided into the West African rift subsystem (WAS) and the Central African rift subsystem (WAS) and the Central African rift subsystem (CAS). WAS basins in Niger and Chad are chiefly extensional, and are filled by up to 13,000 m of Lower Cretaceous to Holocene continental and marine clastics. The basins contain five oil (19-43[degrees]API) and two oil and gas accumulations in Upper Cretaceous and Eocene sandstone reservoirs. The hydrocarbons are sourced and sealed by Upper Cretaceous and Eocene marine and lacustrine shales. The most common structural styles and hydrocarbon traps usually are associated with normal fault blocks. CAS rift basins in Chad and CAR are extensional and transtensional, and are filled by up to 7500 m of chiefly Lower Cretaceous continental clastics. The basins contain eight oil (15-39[degrees]API) and one oil and gas discovery in Lower and Upper Cretaceous sandstone reservoirs. The hydrocarbons are sourced by Lower Cretaceous shales and sealed by interbedded lacustrine and flood-plain shales. Structural styles range from simple fault blocks through complex flower structures. The main hydrocarbon traps are in contractional anticlines. Geological conditions favor the discovery of potentially commercial volumes of oil in WCARS basins, of Niger, Chad and CAR. 108 refs., 24 figs., 4 tabs.« less

Geology of Paleozoic Rocks in the Upper Colorado River Basin in Arizona, Colorado, New Mexico, Utah, and Wyoming, Excluding the San Juan Basin

USGS Publications Warehouse

Geldon, Arthur L.

2003-01-01

The geology of the Paleozoic rocks in the Upper Colorado River Basin in Arizona, Colorado, New Mexico, Utah, and Wyoming, was studied as part of the U.S. Geological Survey's Regional Aquifer-System Analysis Program to provide support for hydrogeological interpretations. The study area is segmented by numerous uplifts and basins caused by folding and faulting that have recurred repeatedly from Precambrian to Cenozoic time. Paleozoic rocks in the study area are 0-18,000 feet thick. They are underlain by Precambrian igneous, metamorphic, and sedimentary rocks and are overlain in most of the area by Triassic formations composed mostly of shale. The overlying Mesozoic and Tertiary rocks are 0-27,000 feet thick. All Paleozoic systems except the Silurian are represented in the region. The Paleozoic rocks are divisible into 11 hydrogeologic units. The basal hydrogeologic unit consisting of Paleozoic rocks, the Flathead aquifer, predominantly is composed of Lower to Upper Cambrian sandstone and quartzite. The aquifer is 0-800 feet thick and is overlain gradationally to unconformably by formations of Cambrian to Mississippian age. The Gros Ventre confining unit consists of Middle to Upper Cambrian shale with subordinate carbonate rocks and sandstone. The confining unit is 0-1,100 feet thick and is overlain gradationally to unconformably by formations of Cambrian to Mississippian age. The Bighom aquifer consists of Middle Cambrian to Upper Ordovician limestone and dolomite with subordinate shale and sandstone. The aquifer is 0-3,000 feet thick and is overlain unconformably by Devonian and Mississipplan rocks. The Elbert-Parting confining unit consists of Lower Devonian to Lower Mississippian limestone, dolomite, sandstone, quartzite, shale, and anhydrite. It is 0-700 feet thick and is overlain conformably to unconformably by Upper Devonian and Mississippian rocks. The Madison aquifer consists of two zones of distinctly different lithology. The lower (Redwall-Leadville) zone is 0-2,500 feet thick and is composed almost entirely of Upper Devonian to Upper Mississippian limestone, dolomite, and chert. The overlying (Darwin-Humbug) zone is 0-800 feet thick and consists of Upper Mississippian limestone, dolomite, sandstone, shale, gypsum, and solution breccia. The Madison aquifer is overlain conformably by Upper Mississippian and Pennsylvanian rocks. The Madison aquifer in most areas is overlain by Upper Mississippian to Middle Pennsylvanian rocks of the Four Comers confining unit. The lower part of this confining unit, the Belden-Molas subunit, consists of as much as 4,300 feet of shale with subordinate carbonate rocks, sandstone, and minor gypsum. The upper part of the confining unit, the Paradox-Eagle Valley subunit, in most places consists of as much as 9,700 feet of interbedded limestone, dolomite, shale, sandstone, gypsum, anhydrite, and halite. Locally, the evaporitic rocks are deformed into diapirs as much as 15,000 feet thick. The Four Corners confining unit is overlain gradationally to disconformably by Pennsylvanian rocks. The uppermost Paleozoic rocks comprise the Canyonlands aquifer, which is composed of three zones with distinctly different lithologies. The basal (Cutler-Maroon) zone consists of as much as 16,500 feet of Lower Pennsylvanian to Lower Permian sandstone, conglomerate, shale, limestone, dolomite, and gypsum. The middle (Weber-De Chelly) zone consists of as much as 4,000 feet of Middle Pennsylvanian to Lower Permian quartz sandstone with minor carbonate rocks and shale. The upper (Park City-State Bridge) zone consists of as much as 800 feet of Lower to Upper Permian limestone, dolomite, shale, sandstone, phosphorite, chert, and gypsum. The Canyonlands aquifer is overlain disconformably to unconformably by formations of Triassic and Jurassic age.

Effects of model layer simplification using composite hydraulic properties

USGS Publications Warehouse

Sepúlveda, Nicasio; Kuniansky, Eve L.

2010-01-01

The effects of simplifying hydraulic property layering within an unconfined aquifer and the underlying confining unit were assessed. The hydraulic properties of lithologic units within the unconfined aquifer and confining unit were computed by analyzing the aquifer-test data using radial, axisymmetric two-dimensional (2D) flow. Time-varying recharge to the unconfined aquifer and pumping from the confined Upper Floridan aquifer (USA) were simulated using 3D flow. Conceptual flow models were developed by gradually reducing the number of lithologic units in the unconfined aquifer and confining unit by calculating composite hydraulic properties for the simplified lithologic units. Composite hydraulic properties were calculated using either thickness-weighted averages or inverse modeling using regression-based parameter estimation. No significant residuals were simulated when all lithologic units comprising the unconfined aquifer were simulated as one layer. The largest residuals occurred when the unconfined aquifer and confining unit were aggregated into a single layer (quasi-3D), with residuals over 100% for the leakage rates to the confined aquifer and the heads in the confining unit. Residuals increased with contrasts in vertical hydraulic conductivity between the unconfined aquifer and confining unit. Residuals increased when the constant-head boundary at the bottom of the Upper Floridan aquifer was replaced with a no-flow boundary.

Geologic assessment of undiscovered oil and gas resources in the Albian Clastic and Updip Albian Clastic Assessment Units, U.S. Gulf Coast Region

USGS Publications Warehouse

Merrill, Matthew D.

2016-03-11

U.S. Geological Survey National Oil and Gas Assessments (NOGA) of Albian aged clastic reservoirs in the U.S. Gulf Coast region indicate a relatively low prospectivity for undiscovered hydrocarbon resources due to high levels of past production and exploration. Evaluation of two assessment units (AUs), (1) the Albian Clastic AU 50490125, and (2) the Updip Albian Clastic AU 50490126, were based on a geologic model incorporating consideration of source rock, thermal maturity, migration, events timing, depositional environments, reservoir rock characteristics, and production analyses built on well and field-level production histories. The Albian Clastic AU is a mature conventional hydrocarbon prospect with undiscovered accumulations probably restricted to small faulted and salt-associated structural traps that could be revealed using high resolution subsurface imaging and from targeting structures at increased drilling depths that were unproductive at shallower intervals. Mean undiscovered accumulation volumes from the probabilistic assessment are 37 million barrels of oil (MMBO), 152 billion cubic feet of gas (BCFG), and 4 million barrels of natural gas liquids (MMBNGL). Limited exploration of the Updip Albian Clastic AU reflects a paucity of hydrocarbon discoveries updip of the periphery fault zones in the northern Gulf Coastal region. Restricted migration across fault zones is a major factor behind the small discovered fields and estimation of undiscovered resources in the AU. Mean undiscovered accumulation volumes from the probabilistic assessment are 1 MMBO and 5 BCFG for the Updip Albian Clastic AU.

Sedimentary conditions of Upper Permian volcano-clastic rocks of Ayan-Yrahskiy anticlinorium (Verhoyansk-Kolyma orogen)

NASA Astrophysics Data System (ADS)

Astakhova, Anna; Khardikov, Aleksandr

2013-04-01

Sedimentation conditions of upper Permian volcano-clastic rocks of Ayan-Yurakhsky anticlinorium are the reason of discussions between researchers. It is important to correctly solve this problem. Investigation allows us to conclude that upper Permian sediments was formed due to high rate deltaic sedimentation on shelf and continental slope of epicontinental sea basin. More than 45 outcrops of upper Permian sediments were described within Ayan-Yurakhsky anticlinorium. Termochemical and X-ray phase, lithological facies, stadial, paleogeographic and others were applied. Investigation allows to classify following types: tuffs, tuffites of andesites, andesi-dacites, sandstone tuffs, siltstone tuffs and claystone tuffs. Two facies were deliniated in the research area: 1) delta channel facies 2) epicontinental sea shelf edge and continental slope. Delta channel facies are located on the south-west part of Aian-Yrahskiy anticlinorium. It is composed of silty packsand and psammitic tuff-siltstone alternation and gravel-psammitic andesi-dacitic tuffute and tuff-breccia bands. Sediments have cross-bedding, through cross-bedding, curvilinear lamination structures. Facies occurred during high rate deltaic sedimentation on the shelf of epicontinental sea. Epicontinental sea shelf edge and continental slope facies are located on the south-west part. Sediments are represented by large thickness tuff-siltstone with tuff-sandstone, tuff-madstone, tuff, tuffite bands and lenses. Large number of submarine landslides sediments provide evidence that there was high angle sea floore environment. 30-50 m diametr eruption centers were described by authors during geological traverses. They are located in Kulu river basin. Their locations are limited by deep-seated pre-ore fault which extended along Ayan-Yurakhsky anticlinorium. U-Pb SHRIMP method showed that the average age of circons, taken from eruption centers, is Permian (256,3±3,7 ma). This fact confirms our emphasis that eruption centers were the centre of underwater effusive explosions which had been occurred in late Permian time. Gold ore deposits mainly localized in the south of Ayan-Yurakhsky anticlinorium and associated with upper Permian deltaic facies sediments. Taking into account lithological facies feature and volcanoclastic origin of sediments it is reasonable to suggest expelled-catagenesis model of gold mineralization. Gold was entered in sedimentary basin with piroclastic material. During catagenesis stage gold migrated from complex of shelf edge and continental slope to fan delta front complex in conjunction with expelled water. The emplacement of ore gold deposits related with upper Permian sediments can be successfully predicted, using this model and associated techniques.

Simulation of the mulltizones clastic reservoir: A case study of Upper Qishn Clastic Member, Masila Basin-Yemen

NASA Astrophysics Data System (ADS)

Khamis, Mohamed; Marta, Ebrahim Bin; Al Natifi, Ali; Fattah, Khaled Abdel; Lashin, Aref

2017-06-01

The Upper Qishn Clastic Member is one of the main oil-bearing reservoirs that are located at Masila Basin-Yemen. It produces oil from many zones with different reservoir properties. The aim of this study is to simulate and model the Qishn sandstone reservoir to provide more understanding of its properties. The available, core plugs, petrophysical, PVT, pressure and production datasets, as well as the seismic structural and geologic information, are all integrated and used in the simulation process. Eclipse simulator was used as a powerful tool for reservoir modeling. A simplified approach based on a pseudo steady-state productivity index and a material balance relationship between the aquifer pressure and the cumulative influx, is applied. The petrophysical properties of the Qishn sandstone reservoir are mainly investigated based on the well logging and core plug analyses. Three reservoir zones of good hydrocarbon potentiality are indicated and named from above to below as S1A, S1C and S2. Among of these zones, the S1A zone attains the best petrophysical and reservoir quality properties. It has an average hydrocarbon saturation of more than 65%, high effective porosity up to 20% and good permeability record (66 mD). The reservoir structure is represented by faulted anticline at the middle of the study with a down going decrease in geometry from S1A zone to S2 zone. It is limited by NE-SW and E-W bounding faults, with a weak aquifer connection from the east. The analysis of pressure and PVT data has revealed that the reservoir fluid type is dead oil with very low gas liquid ratio (GLR). The simulation results indicate heterogeneous reservoir associated with weak aquifer, supported by high initial water saturation and high water cut. Initial oil in place is estimated to be around 628 MM BBL, however, the oil recovery during the period of production is very low (<10%) because of the high water cut due to the fractures associated with many faults. Hence, secondary and tertiary methods are needed to enhance the oil recovery. Water flooding is recommended as the first step of oil recovery enhancement by changing some of high water cut wells to injectors.

Depositional history of the Fire Clay coal bed (Late Duckmantian), Eastern Kentucky, USA

USGS Publications Warehouse

Greb, S.F.; Eble, C.F.; Hower, J.C.

1999-01-01

More than 3800 coal thickness measurements, proximate analyses from 97 localities, and stratigraphic and sedimentological analyses from more than 300 outcrops and cores were used in conjunction with previously reported palynological and petrographic studies to map individual benches of the coal and document bench-scale variability in the Fire Clay (Hazard No. 4) coal bed across a 1860 km2 area of the Eastern Kentucky Coal Field. The bench architecture of the Fire Clay coal bed consists of uncommon leader benches, a persistent but variable lower bench, a widespread, and generally thick upper bench, and local, variable rider benches. Rheotrophic conditions are inferred for the leader benches and lower bench based on sedimentological associations, mixed palynomorph assemblages, locally common cannel coal layers, and generally high ash yields. The lower bench consistently exhibits vertical variability in petrography and palynology that reflects changing trophic conditions as topographic depressions infilled. Infilling also led to unconfined flooding and ultimately the drowning of the lower bench mire. The drowned mire was covered by an air-fall volcanic-ash deposit, which produced the characteristic flint clay parting. The extent and uniform thickness of the parting suggests that the ash layer was deposited in water on a relatively flat surface without a thick canopy or extensive standing vegetation across most of the study area. Ash deposits led to regional ponding and establishment of a second planar mire. Because the topography had become a broadly uniform, nutrient-rich surface, upper-bench peats became widespread with large areas of the mire distant to clastic sources. Vertical sections of thick (> 70 cm), low-ash yield, upper coal bench show a common palynomorph change from arborescent lycopod dominance upward to fern and densospore-producing, small lycopod dominance, inferred as a shift from planar to ombrotrophic mire phases. Domed mires appear to have been surrounded by wide areas of planar mires, where the coal was thinner (< 70 cm), higher in ash yield, and dominated by arborescent lycopods. Rectangular thickness trends suggest that syndepositional faulting influenced peat accumulation, and possibly the position of the domed mire phase. Faulting also influenced post-depositional clastic environments of deposition, resulting in sandstone channels with angular changes in orientation. Channels and lateral facies were locally draped by high-ash-yield rider coal benches, which sometimes merged with the upper coal bench. These arborescent-lycopod dominant rider coal benches were profoundly controlled by palcotopography, much like the leader coal benches. Each of the benches of coal documented here represent distinctly different mires that came together to form the Fire Clay coal bed, rather than a single mire periodically split by clastic influx. This is significant as each bench of the coal has its own characteristics, which contribute to the total coal characteristics. The large data set allows interpretation of both vertical and lateral limits to postulated domed phases in the upper coal bench, and to the delineation of subtle tectonic structures that allow for meaningful thickness projections beyond the limits of present mining.A study was conducted to analyze the depositional history of the Fire Clay coal bed in the eastern Kentucky coal field. The study involved over 3800 coal thickness measurements, proximate analyses from 97 localities, and stratigraphic and sedimentological analyses from more than 300 outcrops and cores in conjunction with previously reported palynological and petrographic studies to map individual benches of the coal and document bench-scale variability.

Revised hydrogeologic framework of the Floridan aquifer system in the northern coastal area of Georgia and adjacent parts of South Carolina

USGS Publications Warehouse

Williams, Lester J.; Gill, Harold E.

2010-01-01

The hydrogeologic framework for the Floridan aquifer system has been revised for eight northern coastal counties in Georgia and five coastal counties in South Carolina by incorporating new borehole geophysical and flowmeter log data collected during previous investigations. Selected well logs were compiled and analyzed to determine the vertical and horizontal continuity of permeable zones that make up the Upper and Lower Floridan aquifers and to define more precisely the thickness of confining beds that separate these aquifers. The updated framework generally conforms to the original framework established by the U.S. Geological Survey in the 1980s except for adjustments made to the internal boundaries of the Upper and Lower Floridan aquifers and the individual permeable zones that compose these aquifers. The revised boundaries of the Floridan aquifer system were mapped by taking into account results from local studies and regional correlations of geologic and hydrogeologic units. Because the revised framework does not match the previous regional framework along all edges, additional work will be needed to expand the framework into adjacent areas. The Floridan aquifer system in the northern coastal region of Georgia and parts of South Carolina can be divided into the Upper and Lower Floridan aquifers, which are separated by a middle confining unit of relatively lower permeability. The Upper Floridan aquifer includes permeable and hydraulically connected carbonate rocks of Oligocene and upper Eocene age that represent the most transmissive part of the aquifer system. The middle confining unit consists of low permeability carbonate rocks that lie within the lower part of the upper Eocene in Beaufort and Jasper Counties, South Carolina, and within the upper to middle parts of the middle Eocene elsewhere. Locally, the middle confining unit contains thin zones that have moderate to high permeability and can produce water to wells that tap them. The Lower Floridan aquifer includes all permeable strata that lie below the middle confining unit and above the base of the aquifer system. Beneath Hilton Head Island, South Carolina, the middle Floridan aquifer is now included as part of the Lower Floridan aquifer. The base of the Floridan aquifer system generally is located at the top of lower Eocene rocks in Georgia and the top of Paleocene rocks in South Carolina. The Upper and Lower Floridan aquifers are interconnected to varying degrees depending on the thickness and permeability of the middle confining unit that separates these aquifers. In most places, hydraulic head differences between the two aquifers range from a few inches to a few feet or more. Monitoring at several vertically clustered well-point sites where wells were set at different depths in the aquifer revealed variations in the degree of hydraulic separation with depth. In general, the head separation between the Upper and Lower Floridan aquifers increases with depth, which indicates that the deeper zones are more hydraulically separated than the shallower parts of the Lower Floridan aquifer.

Groundwater conditions and studies in the Augusta–Richmond County area, Georgia, 2008–2009

USGS Publications Warehouse

Gonthier, Gerard; Lawrence, Stephen J.; Peck, Michael F.; Holloway, O. Gary

2011-01-01

Groundwater studies and monitoring efforts conducted during 2008–2009, as part of the U.S. Geological Survey (USGS) Cooperative Water Program with the City of Augusta in Richmond County, Georgia, provided data for the effective management of local water resources. During 2008–2009 the USGS completed: (1) installation of three monitoring wells and the collection of lithologic and geophysical logging data to determine the extent of hydrogeologic units, (2) collection of continuous groundwater-level data from wells near Well Fields 2 and 3, (3) collection of synoptic groundwater-level measurements and construction of potentiometric-surface maps in Richmond County to establish flow gradients and groundwater-flow directions in the Dublin and Midville aquifer systems, (4) completion of a 24-hour aquifer test to determine hydraulic characteristics of the lower Dublin aquifer, and upper and lower Midville aquifers in Well Field 2, and (5) collection of groundwater samples from selected wells in Well Field 2 for laboratory analysis of volatile organic compounds and groundwater tracers to assess groundwater quality and estimate the time of groundwater recharge. Potentiometric-surface maps of the Dublin and Midville aquifer systems for 2008–2009 indicate that the general groundwater flow direction within Richmond County is eastward toward the Savannah River, with the exception of the area around Well Field 2, where pumping interrupts the eastward flow of water toward the Savannah River and causes flow lines to bend toward the center of pumping. Results from a 24-hour aquifer test conducted in 2009 within the upper and lower Midville aquifers at Well Field 2 indicated a transmissivity and storativity for the upper and lower Midville aquifers, combined, of 4,000 feet-squared per day and 2x10-4, respectively. The upper and lower Midville aquifers and the middle lower Midville confining unit, which is 85-feet thick in this area, yielded horizontal hydraulic conductivity and specific storage values of about 45 feet per day and 2x10-6 ft-1, respectively. Results from the 24-hour aquifer test also indicate a low horizontal hydraulic conductivity for the lower Dublin aquifer of less than 1 foot per day. Of the 35 volatile organic compounds (VOCs) analyzed in 23 groundwater samples during 2008–2009, only six were detected above laboratory reporting limits in samples from eight wells. No concentration in groundwater samples collected during 2008–2009 exceeded drinking water standards. Trichloroethene had the maximum VOC concentration (1.9 micrograms per liter) collected from a water sample during 2008–2009. Water-quality sampling of several wells near Well Field 2 indicate that, while in operation, the northernmost production well might have diverted groundwater, containing low levels of trichloroethene from at least two other production wells. Analysis of sulfur hexafluoride data indicate the average year of recharge ranges between 1981 and 1984 for water samples from five wells open to the upper and lower Midville aquifers, and 1991 for a water sample from one shallow well open to the lower Dublin aquifer. All of these ages suggest a short flow path and nearby source of contamination. The actual source of low levels of VOCs at Well Field 2 remains unknown. Three newly installed monitoring wells indicate that hydrogeologic units beneath Well Fields 2 and 3 are composed of sand and clay layers. Hydrogeologic units, encountered at Well Field 2, in order of increasing depth are the lower Dublin confining unit, lower Dublin aquifer, upper Midville confining unit, upper Midville aquifer, lower Midville confining unit, and lower Midville aquifer. West of Well Field 3, hydrogeologic units, in order of increasing depth are the Upper Three Runs aquifer, Gordon confining unit, Gordon aquifer, lower Dublin confining unit, lower Dublin aquifer, upper Midville confining unit, upper Midville aquifer, lower Midville confining unit, and lower Midville aquifer.

Petroleum geology and resources of the Baykit High province, East Siberia, Russia

USGS Publications Warehouse

Ulmishek, Gregory F.

2001-01-01

The Baykit High province consists of two principal structural units?the Baykit regional high in the west, which occupies most of the province, and the Katanga structural saddle in the east. The province is on the western margin of the Siberian craton east of theYenisey Ridge foldbelt. The province is an exploration frontier and only a few prospects have been drilled. The oldest sedimentary rocks of the province, Riphean carbonate and clastic strata of Late Proterozoic age (1,650?650 million years old) that were deposited on the passive margin, cover the Archean?Lower Proterozoic basement. Basal Vendian (uppermost Proterozoic, 650?570 million years old) clastic rocks unconformably overlie various units of the Riphean and locally lie directly on the basement. Younger Vendian and lowermost Cambrian rocks are primarily dolomites. The Vendian/Cambrian boundary is con-formable, and its exact stratigraphic position has not been identified with certainty. The Lower Cambrian section is thick, and it consists of alternating beds of dolomite and evaporites (mostly salt). Middle and Upper Cambrian strata are composed of shale and dolomite. Ordovician-Silurian and upper Paleozoic rocks are thin, and they are present only in the northern areas of the province. Structural pattern of Riphean rocks differs substantially from that of Vendian-Cambrian rocks. A single total petroleum system (TPS) was identified in the Baykit High province. Discovered oil of the system is chiefly concentrated in Riphean carbonate reservoirs of the Yurubchen-Tokhom zone that is currently being explored and that has the Abstract 1 potential to become a giant field (or group of fields). The TPS also contains about 5 trillion cubic feet of discovered recover-able gas in clastic reservoir rocks at the base of the Vendian section. Petroleum source rocks are absent in the stratigraphic succession over most of the TPS area. Riphean organic-rich shales and carbonates that crop out in the Yenisey Ridge foldbelt west of the Baykit high are probable source rocks. Their areal distribution extends from the foldbelt into the foredeep along the province?s western margin. Potential source rocks also are present in platform depressions in eastern areas of the province. Hydrocarbon generation and migration west of the province started as early as Riphean time, before the beginning of the deformation in the Yenisey Ridge foldbelt that occurred about 820?850 million years ago. However, the presently known oil and gas accumulations were formed after deposition of the Lower Cambrian salt seal. Available data allow identification of only one assessment unit, and it covers the entire TPS area. Undiscovered oil and gas resources are moderate, primarily due to the poor quality of reservoir rocks. However, the reserve growth in the Yurubchen-Tokhom zone may be large and may exceed the volume of undiscovered resources in the rest of the province. Most oil and gas resourcesareexpectedtobeinstructuralandstratigraphictrapsin Riphean carbonate reservoirs. Vendian clastic reservoirs are probably gas-prone.

Understanding the mechanical and acoustical characteristics of sand aggregates compacting under triaxial conditions

NASA Astrophysics Data System (ADS)

Hangx, Suzanne; Brantut, Nicolas

2016-04-01

Mechanisms such as grain rearrangement, coupled with elastic deformation, grain breakage, grain rearrangement, grain rotation, and intergranular sliding, play a key role in determining porosity and permeability reduction during burial of clastic sediments. Similarly, in poorly consolidated, highly porous sands and sandstones, grain rotation, intergranular sliding, grain failure, and pore collapse often lead to significant reduction in porosity through the development of compaction bands, with the reduced porosity and permeability of such bands producing natural barriers to flow within reservoir rocks. Such time-independent compaction processes operating in highly porous water- and hydrocarbon-bearing clastic reservoirs can exert important controls on production-related reservoir deformation, subsidence, and induced seismicity. We performed triaxial compression experiments on sand aggregates consisting of well-rounded Ottawa sand (d = 300-400 μm; φ = 36.1-36.4%) at room temperature, to systematically investigate the effect of confining pressure (Pceff = 5-100 MPa), strain rate (10-6-10-4 s-1) and chemical environment (decane vs. water; Pf = 5 MPa) on compaction. For a limited number of experiments grain size distribution (d = 180-500 μm) and grain shape (subangular Beaujean sand; d = 180-300 μm) were varied to study their effect. Acoustic emission statistics and location, combined with microstructural and grain size analysis, were used to verify the operating microphysical compaction mechanisms. All tests showed significant pre-compaction during the initial hydrostatic (set-up) phase, with quasi-elastic loading behaviour accompanied by permanent deformation during the differential loading stage. This permanent volumetric strain involved elastic grain contact distortion, particle rearrangement, and grain failure. From the acoustic data and grain size analysis, it was evident that at low confining pressure grain rearrangement controlled compaction, with grain failure being present but occurring to a relatively limited extent. Acoustic emission localization showed that failure was focussed along a broad shear plane. At higher confining pressure pervasive grain failure clearly accommodated compaction, though no strain localization was observed and failure appeared to be through cataclastic flow. Chemical environment, i.e. chemically inert decane vs. water as a pore fluid, had no significant effect on compaction in the strain rate range tested. Grain size distribution or grain shape also appeared to not affect the observed mechanical behaviour. Our results can be used to better understand the compaction behaviour of poorly consolidated sandstones. Future research will focus on understanding the effect of cementation on strain localization in deforming artificial Ottawa sandstone.

Hydrologeology and water quality of the Floridan aquifer system and effect of Lower Floridan aquifer pumping on the Upper Floridan aquifer, Pooler, Chatham County, Georgia, 2011–2012

USGS Publications Warehouse

Gonthier, Gerard

2012-01-01

Two test wells were completed in Pooler, Georgia, in 2011 to investigate the potential of using the Lower Floridan aquifer as a source of water for municipal use. One well was completed in the Lower Floridan aquifer at a depth of 1,120 feet (ft) below land surface; the other well was completed in the Upper Floridan aquifer at a depth of 486 ft below land surface. At the Pooler test site, the U.S. Geological Survey performed flowmeter surveys, packer-isolated slug tests within the Lower Floridan confining unit, slug tests of the entire Floridan aquifer system, and aquifer tests of the Upper and Lower Floridan aquifers. Drill cuttings, geophysical logs, and borehole flowmeter surveys indicate that the Upper Floridan aquifer extends 333 –515 ft below land surface, the Lower Floridan confining unit extends 515–702 ft below land surface, and the Lower Floridan aquifer extends 702–1,040 ft below land surface. Flowmeter surveys indicate that the Upper Floridan aquifer contains two water-bearing zones at depth intervals of 339 –350 and 375–515 ft; the Lower Floridan confining unit contains one zone at a depth interval of 550–620 ft; and the Lower Floridan aquifer contains five zones at depth intervals of 702–745, 745–925, 925–984, 984–1,015, and 1,015–1,040 ft. Flowmeter testing of the test borehole open to the entire Floridan aquifer system indicated that the Upper Floridan aquifer contributed 92.4 percent of the total flow rate of 708 gallons per minute; the Lower Floridan confining unit contributed 3.0 percent; and the Lower Floridan aquifer contributed 4.6 percent. Horizontal hydraulic conductivity of the Lower Floridan confining unit derived from slug tests within three packer-isolated intervals ranged from 0.5 to 10 feet per day (ft/d). Aquifer-test analyses yielded values of transmissivity for the Upper Floridan aquifer, Lower Floridan confining unit, and the Lower Floridan aquifer of 46,000, 700, and 4,000 feet squared per day (ft2/d), respectively. Horizontal hydraulic conductivity of 4 ft/d for the Lower Floridan confining unit, derived from aquifer-test analyses, is near the midrange for values derived from packer-isolated slug tests. The transmissivity of the entire Floridan aquifer system derived from aquifer-test analyses totals about 51,000 ft2/d, similar to the value of 58,000 ft2/d derived from open slug tests on the entire Floridan aquifer system. Water-level data for each aquifer test were filtered for external influences such as barometric pressure, earth-tide effects, and long-term trends to enable detection of small (less than 1 foot) water-level responses to aquifer-test pumping. During the 72-hour aquifer test of pumping the Lower Floridan aquifer, a drawdown response of 51.7 ft was observed in the Lower Floridan pumped well and a drawdown response of 0.9 foot was observed in the Upper Floridan observation well located 85 ft from the pumped well.

Scarps Confined to Crater Floors

NASA Image and Video Library

2000-01-15

This image, from NASA Mariner 10 spacecraft which launched in 1974, shows several scarps, which appear to be confined to crater floors. The scarp in the crater at the upper left of the image has been diverted by the central peaks.

Subsurface stratigraphy of upper Devonian clastics in southern West Virginia

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

Neal, D.W.; Patchen, D.G.

Studies of upper Devonian shales and siltstones in southern West Virginia have resulted in a refinement of the stratigraphic framework used in characterizing the gas-producing Devonian shales. Gamma-ray log correlation around the periphery of the Appalachian Basin has extended the usage of New York stratigraphic nomenclature for the interval between the base of the Dunkirk shale and the top of the Tully limestone to southern West Virginia. Equivalents of the Dunkirk shale and younger rocks of New York are recognized in southwestern West Virginia and are named according to Ohio usage. Gas production is primarily from the basal black shalemore » member of the Ohio shale. Gas shows from older black shale units (Rhinestreet and Marcellus shales) are recorded from wells east of the major producing trend. Provided suitable stimulation techniques can be developed, these older and deeper black shales may prove to be another potential gas resource.« less

Biostratigraphy of the Cretaceous/Tertiary boundary in the Sirwan Valley (Sulaimani Region, Kurdistan, NE Iraq)

NASA Astrophysics Data System (ADS)

Sharbazheri, Khalid Mahmood; Ghafor, Imad Mahmood; Muhammed, Qahtan Ahmad

2009-10-01

The Cretaceous/Tertiary (K/T) boundary sequence, which crops out in the studied area is located within the High Folded Zone, in the Sirwan Valley, northeastern Iraq. These units mainly consist of flysch and flysch-type successions of thick clastic beds of Tanjero/Kolosh Formations. A detailed lithostratigraphic study is achieved on the outcropping uppermost part of the Upper Cretaceous successions (upper part of Tanjero Formation) and the lowermost part of the Kolosh Formation. On the basis of the identified planktonic foraminiferal assemblages, five biozones are recorded from the uppermost part of Tanjero Formation and four biozones from the lower part of the Kolosh Formation (Lower Paleocene) in the Sirwan section. The biostratigraphic correlations based on planktonic foraminiferal zonations showed a comparison between the biostratigraphic zones established in this study and other equivalents of the commonly used planktonic zonal scheme around the Cretaceous/Tertiary boundary in and outside Iraq.

Hydrogeologic framework of the North Fork and surrounding areas, Long Island, New York

USGS Publications Warehouse

Schubert, Christopher E.; Bova, Richard G.; Misut, Paul E.

2004-01-01

Ground water on the North Fork of Long Island is the sole source of drinking water, but the supply is vulnerable to saltwater intrusion and upconing in response to heavy pumping. Information on the area's hydrogeologic framework is needed to analyze the effects of pumping and drought on ground-water levels and the position of the freshwater-saltwater interface. This will enable water-resource managers and water-supply purveyors to evaluate a wide range of water-supply scenarios to safely meet water-use demands. The extent and thickness of hydrogeologic units and position of the freshwater-saltwater interface were interpreted from previous work and from exploratory drilling during this study.The fresh ground-water reservoir on the North Fork consists of four principal freshwater flow systems (referred to as Long Island mainland, Cutchogue, Greenport, and Orient) within a sequence of unconsolidated Pleistocene and Late Cretaceous deposits. A thick glacial-lake-clay unit appears to truncate underlying deposits in three buried valleys beneath the northern shore of the North Fork. Similar glacial-lake deposits beneath eastern and east-central Long Island Sound previously were inferred to be younger than the surficial glacial deposits exposed along the northern shore of Long Island. Close similarities in thickness and upper-surface altitude between the glacial-lake-clay unit on the North Fork and the glacial-lake deposits in Long Island Sound indicate, however, that the two are correlated at least along the North Fork shore.The Matawan Group and Magothy Formation, undifferentiated, is the uppermost Cretaceous unit on the North Fork and constitutes the Magothy aquifer. The upper surface of this unit contains a series of prominent erosional features that can be traced beneath Long Island Sound and the North Fork. Northwest-trending buried ridges extend several miles offshore from areas southeast of Rocky Point and Horton Point. A promontory in the irregular, north-facing cuesta slope extends offshore from an area southwest of Mattituck Creek and James Creek. Buried valleys that trend generally southeastward beneath Long Island Sound extend onshore northeast of Hashamomuck Pond and east of Goldsmith Inlet.An undifferentiated Pleistocene confining layer, the lower confining unit, consists of apparently contiguous units of glacial-lake, marine, and nonmarine clay. This unit is more than 200 feet thick in buried valleys filled with glacial-lake clay along the northern shore, but elsewhere on the North Fork, it is generally less than 50 feet thick and presumably represents an erosional remnant of marine clay. Its upper surface is generally 75 feet or more below sea level where it overlies buried valleys, and is generally 100 feet or less below sea level in areas where marine clay has been identified.A younger unit of glacial-lake deposits, the upper confining unit, is a local confining layer and underlies a sequence of late Pleistocene moraine and outwash deposits. This unit is thickest (more than 45 feet thick) beneath two lowland areas--near Mattituck Creek and James Creek, and near Hashamomuck Pond--but pinches out close to the northern and southern shores and is locally absent in inland areas of the North Fork. Its upper-surface altitude generally rises to near sea level toward the southern shore.Freshwater in the Orient flow system is limited to the upper glacial aquifer above the top of the lower confining unit. The upper confining unit substantially impedes the downward flow of freshwater in inland parts of the Greenport flow system. Deep freshwater within the lower confining unit in the east-central part of the Cutchogue flow system probably is residual from an interval of lower sea level. The upper confining unit is absent or only a few feet thick in the west-central part of the Cutchogue flow system and does not substantially impede the downward flow of freshwater, but the lower confining unit probably impedes the downward flow of freshwater within a southeast-trending buried valley in this area.

Estimated discharge and chemical-constituent loading from the upper Floridan aquifer to the lower St John's River, northeastern Florida, 1990-91

USGS Publications Warehouse

Spechler, R.M.

1995-01-01

The lower St. Johns River, a 101-mile long segment of the St. Johns River, begins at the confluence of the Ocklawaha River and ends where the river discharges into the Atlantic Ocean at Mayport. The St. Johns River is affected by tides as far upstream as Lake George, 106 miles from the mouth. Saltwater from the ocean advances inland during each incoming tide and recedes during each outgoing tide. The chemical quality of the lower St. Johns River is highly variable primarily because of the inflow of saltwater from the ocean, and in some areas, from the discharge of mineralized ground water. Three hydrogeologic units are present in the study area: the surficial aquifer system, the intermediate confining unit, and the Floridan aquifer system. The surficial aquifer system overlies the intermediate confining unit and consists of deposits containing sand, clay, shell, and some limestone and dolomite. The intermediate confining unit underlies all of the study area and retards the vertical movement of water between the surficial aquifer system and the Floridan aquifer system. The intermediate confining unit consists of beds of relatively low permeability sediments that vary in thickness and areal extent and can be breached by sinkholes, fractures, and other openings. The Floridan aquifer system primarily consists of limestone and dolomite. The quality of water in the Upper Floridan aquifer varies throughout the study area. Dissolved solids in water range from about 100 to more than 5,000 milligrams per liter. Chloride and sulfate concentrations in water from the Upper Floridan aquifer range from about 4 to 3,700 milligrams per liter and from 1 to 1,300 milligrams per liter, respectively. The rate of leakage through the intermediate confining unit is controlled by the leakance coefficient of the intermediate confining unit and by the head difference between the Upper Floridan aquifer and the surficial aquifer system. The total ground-water discharge from the Upper Floridan aquifer to the St. Johns River within the lower St. Johns River drainage basin, based on the potentiometric surface of the Upper Floridan aquifer in September 1990, was estimated to be 86 cubic feet per second. Total estimated ground-water discharge to the lower St. Johns River in September 1991, when heads in the Upper Floridan aquifer averaged about 4 feet higher than in 1990, was 133 cubic feet per second. The load of dissolved-solids that discharged from the Upper Floridan aquifer into the lower St. Johns River on the basis of September 1990 heads is estimated to be 47,000 tons per year. Estimated chloride and sulfate loads are 18,000 and 9,500 tons per year, respectively. Dissolved-solids, chloride, and sulfate loads discharging into the lower St. Johns River are estimated to be 81,000, 39,000, and 15,000 tons per year, respectively, on the basis of September 1991 heads.

Suspected microbial-induced sedimentary structures (MISS) in Furongian (Upper Cambrian; Jiangshanian, Sunwaptan) strata of the Upper Mississippi Valley

USGS Publications Warehouse

Eoff, Jennifer D.

2014-01-01

The Furongian (Upper Cambrian; Jiangshanian and Sunwaptan) Tunnel City Group (Lone Rock Formation and Mazomanie Formation), exposed in Wisconsin and Minnesota, represents a shallow-marine clastic environment during a time of exceptionally high sea level. Lithofacies from shoreface to transitional-offshore settings document deposition in a wave- and storm-dominated sea. Flooding of the cratonic interior was associated with formation of a condensed section and the extensive development of microbial mats. Biolamination, mat fragments, wrinkle structures, and syneresis cracks are preserved in various sandstone facies of the Lone Rock Formation, as is evidence for the cohesive behavior of sand. These microbial-induced sedimentary structures (MISS) provide unique signals of biological–physical processes that physical structures alone cannot mimic. The MISS are associated with a trilobite extinction event in the Steptoean–Sunwaptan boundary interval. This may support recent claims that Phanerozoic microbial mats were opportunistic disaster forms that flourished during periods of faunal turnover. Further investigation of stratigraphic, taphonomic, and other potential biases, however, is needed to fully test this hypothesis.

The Laughlin liquid in an external potential

NASA Astrophysics Data System (ADS)

Rougerie, Nicolas; Yngvason, Jakob

2018-04-01

We study natural perturbations of the Laughlin state arising from the effects of trapping and disorder. These are N-particle wave functions that have the form of a product of Laughlin states and analytic functions of the N variables. We derive an upper bound to the ground state energy in a confining external potential, matching exactly a recently derived lower bound in the large N limit. Irrespective of the shape of the confining potential, this sharp upper bound can be achieved through a modification of the Laughlin function by suitably arranged quasi-holes.

Map showing distribution of small-scale deformation structures in a part of the upper coastal plain of South Carolina and adjacent Georgia

USGS Publications Warehouse

McDowell, R.C.; Houser, B.B.

1983-01-01

Fieldwork was done principally by vehicle along roads, but also included railroad cuts and excavation sites, such as quarries and landfills. Natural exposures are rare and provided no examples of deformation structures for this study. The geologic units exposed in the area are chiefly clastic sediments deposited in nearshore marine to continental environments. They include semi-consolidated sand, silt, clay, and rare thin impure limestone beds of Late Cretaceous to Eocene age (fig. 2). These sedimentary beds generally have a gentle regional dip to the southeast (Faye and Prowell, 1982, p. 6).

Geochemical characteristics of Holocene laminated sapropel (unit II) and underlying lacustrine unit III in the Black Sea

USGS Publications Warehouse

Dean, Walter E.; Arthur, Michael A.

2011-01-01

eg 1 of the 1988 R/V Knorr expeditions to the Black Sea recovered 90 gravity and box cores. The longest recovery by gravity cores was about 3 meters, with an average of about 2.5 meters, recovering all of the Holocene and upper Pleistocene sections in the Black Sea. During the latest Pleistocene glaciation, sea level dropped below the 35-meters-deep Bosporus outlet sill of the Black Sea. Therefore throughout most of its history the Black Sea was a lake, and most of its sediments are lacustrine. The oldest sediments recovered (older than 8,000 calendar years) consist of massive to coarsely banded lacustrine calcareous clay designated as lithologic Unit III, generally containing less than 1 percent organic carbon (OC). The base of overlying Unit II marks the first incursion of Mediterranean seawater into the Black Sea, and the onset of bottom-water anoxia about 7,900 calendar years. Unit II contains as much as 15 percent OC in cores from the deepest part of the Black Sea (2,200 meters). The calcium carbonate (CaCO3) remains of the coccolith Emiliania huxleyi form the distinctive white laminae of overlying Unit I. The composition of Unit III and Unit II sediments are quite different, reflecting different terrigenous clastic sources and increased contributions from hydrogenous and biogenic components in anoxic Unit II sapropel. In Unit II, positive covariance between OC and three trace elements commonly concentrated in OC-rich sediments where sulfate reduction has occurred (molybdenum, nickel, and vanadium) and a nutrient (phosphorus) suggest a large marine source for these elements although nickel and vanadium also have a large terrigenous clastic source. The marine sources may be biogenic or hydrogenous. A large biogenic source is also suggested for copper and cobalt. Because abundant pyrite forms in the water column and sediments of the Black Sea, we expected to find a large hydrogenous iron component, but a strong covariance of iron with aluminum suggests that the dominant source of iron is from terrigenous clastic material. Most elements in lacustrine Unit III sediments have a strong covariance with Al indicating a very dominant terrigenous source. In Unit II, some elements, especially nickel, molybdenum, vanadium, and zinc, do not correlate with aluminum and have concentrations well above terrigenous clastic material, indicating a marine source.

Hydrogeology at Air Force Plant 4 and vicinity and water quality of the Paluxy Aquifer, Fort Worth, Texas

USGS Publications Warehouse

Kuniansky, Eve L.; Jones, Sonya A.; Brock, Robert D.; Williams, M.D.

1996-01-01

Ground water in the surficial terrace alluvial aquifer is contaminated at Air Force Plant 4, Fort Worth, Texas, and at the adjacent Naval Air Station. Some of the contaminated water has leaked from the terrace alluvial aquifer to an uppermost interval of the Paluxy Formation (the Paluxy "upper sand") beneath the east parking lot, east of the assembly building, and to the upper and middle zones of the Paluxy aquifer near Bomber Road, west of the assembly building. Citizens are concerned that contaminants from the plant, principally trichloroethylene and chromium might enter nearby municipal and domestic wells that pump water from the middle and lower zones of the Paluxy aquifer. Geologic formations that crop out in the study area, from oldest to youngest, are the Paluxy Formation (aquifer), Walnut Formation (confining unit), and Goodland Limestone (confining unit). Beneath the Paluxy Formation is the Glen Rose Formation (confining unit) and Twin Mountains Formation (aquifer). The terrace alluvial deposits overlie these Cretaceous rocks. The terrace alluvial aquifer, which is not used for municipal water supply, is separated from the Paluxy aquifer by the Goodland-Walnut confining unit. The confining unit restricts the flow of ground water between these aquifers in most places; however, downward leakage to the Paluxy aquifer might occur through the "window," where the confining unit is thin or absent. The Paluxy aquifer is divided into upper, middle, and lower zones. The Paluxy "upper sand" underlying the "window" is an apparently isolated, mostly unsaturated, sandy lens within the uppermost part of the upper zone. The Paluxy aquifer is recharged by leakage from Lake Worth and by precipitation on the outcrop area. Discharge from the aquifer primarily occurs as pumpage from municipal and domestic wells. The Paluxy aquifer is separated from the underlying Twin Mountains aquifer by the Glen Rose confining unit. Water-level maps indicate that (1) ground water in the terrace alluvial aquifer appears to flow outward, away from Air Force Plant 4; (2) a ground-water mound, possibly caused by downward leakage from the terrace alluvial aquifer, is present in the Paluxy "upper sand" beneath the "window;" and (3) lateral ground-water flow in regionally extensive parts of the Paluxy aquifer is from west to east-southeast. Trichloroethylene concentrations at Air Force Plant 4 have ranged from about 10,000 to about 100,000 micrograms per liter in the terrace alluvial aquifer, from 8,000 to 11,000 micrograms per liter in the Paluxy "upper sand," and from 2 to 50 micrograms per liter in the upper and middle zones of the Paluxy aquifer. Chromium concentrations at Air Force Plant 4 have ranged from 0 to 629 micrograms per liter in the terrace alluvial aquifer. The seven municipal wells mostly west and south of Air Force Plant 4 are not along a flowpath for leakage of contaminants from the plant because ground-water flow in the Paluxy aquifer is toward the east-southeast. Furthermore, trichloroethylene was not detected in any of these wells in 1993 when all were sampled for water quality. The results of water-quality sampling at 10 domestic wells northwest of the Air Force Plant 4 during April 1993 and April 1995 indicated that neither trichloroethylene nor chromium had migrated off-site to these wells.

Influence of depositional environment on diagenesis in St. Peter sandstone, Michigan basin

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

Lundgren, C.E. Jr.; Barnes, D.A.

1989-03-01

The Middle Ordovician St. Peter Sandstone in the Michigan basin was deposited in marine peritidal to storm-dominated, outer shelf depositional environments that evolved in a regionally significant transgressive pattern. The formation is bounded by carbonate and shaly clastic strata of the Prairie du Chien Group below and is transitional to condensed sequence clastics and carbonates of the Glenwood Formation above. Sedimentologic and petrographic analysis of conventional core from 25 wells suggests that reservoir quality in the formation is strongly dependent on a complex diagenetic history, especially the nature and subsequent dissolution of intergranular carbonate in the sandstone. Petrographic evidence indicatesmore » that porosity in the formation formed by dissolution of precursor dolomite of various origins and, locally, the formation of pore-filling authigenic clay (chlorite-illite). Authigenic clay is the incongruent dissolution product of dolomite, detrital K-feldspar, and, possibly, muscovite and results in diminished reservoir quality where abundant in the St. Peter Sandstone. Authigenic clay is volumetrically more significant in the upper portions of the formation and is associated with higher concentrations of detrital K-feldspar. Depositional facies controlled the distribution and types of intergranular carbonate (now dolomite) and detrital K-feldspar in the St. Peter Sandstone and hence reservoir quality; both components were more significant in storm-shelf sandstone facies.« less

Chemical Characteristics, Water Sources and Pathways, and Age Distribution of Ground Water in the Contributing Recharge Area of a Public-Supply Well near Tampa, Florida, 2002-05

USGS Publications Warehouse

Katz, Brian G.; Crandall, Christy A.; Metz, Patricia A.; McBride, W. Scott; Berndt, Marian P.

2007-01-01

In 2001, the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey began a series of studies on the transport of anthropogenic and natural contaminants (TANC) to public-supply wells. The main goal of the TANC program was to better understand the source, transport, and receptor factors that control contaminant movement to public-supply wells in representative aquifers of the United States. Studies were first conducted at regional scales at four of the eight TANC study areas during 2002-03 and at small (local) scales during 2003-05 in California, Nebraska, Connecticut, and Florida. In the Temple Terrace study area near Tampa, Florida, multiple chemical indicators and geochemical and ground-water flow modeling techniques were used to assess the vulnerability of a public-supply well in the karstic Upper Floridan aquifer to contamination from anthropogenic and naturally occurring contaminants. During 2003-05, water samples were collected from the public-supply well and 13 surrounding monitoring wells that all tap the Upper Floridan aquifer, and from 15 monitoring wells in the overlying surficial aquifer system and the intermediate confining unit that are located within the modeled ground-water contributing recharge area of the public-supply well. Six volatile organic compounds and four pesticides were detected in trace concentrations (well below drinking-water standards) in water from the public-supply well, which had an open interval from 36 to 53 meters below land surface. These contaminants were detected more frequently in water samples from monitoring wells in the overlying clastic surficial aquifer system than in water from monitoring wells in the Upper Floridan aquifer in the study area. Likewise, nitrate-N concentrations in the public-supply well (0.72-1.4 milligrams per liter) were more similar to median concentrations in the oxic surficial aquifer system (2.1 milligrams per liter) than to median nitrate-N concentrations in the anoxic Upper Floridan aquifer (0.06 milligram per liter) under sulfate-reducing conditions. High concentrations of radon-222 and uranium in the public-supply well compared to those in monitoring wells in the Upper Floridan aquifer appear to originate from water moving downward through sands and discontinuous clay lenses that overlie the aquifer. Water samples also were collected from three overlapping depth intervals (38-53, 43-53, and 49-53 meters below land surface) in the public-supply well. The 49- to 53-meter interval was identified as a high-flow zone during geophysical logging of the wellbore. Water samples were collected from these depth intervals at a low pumping rate by placing a low-capacity submersible pump (less than 0.02 cubic meter per minute) at the top of each interval. To represent higher pumping conditions, a large-capacity portable submersible pump (1.6 cubic meters per minute) was placed near the top of the open interval; water-chemistry samples were collected using the low-capacity submersible pump. The 49- to 53-meter depth interval had distinctly different chemistry than the other two sampled intervals. Higher concentrations of nitrate-N, atrazine, radon, trichloromethane (chloroform), and arsenic (and high arsenic (V)/arsenic (III) ratios); lower concentrations of dissolved solids, strontium, iron, manganese, and lower nitrogen and sulfur isotope ratios were found in this highly transmissive zone in the limestone than in water from the two other depth intervals. Movement of water likely occurs from the overlying sands and clays of the oxic surficial aquifer system and intermediate confining unit (that contains high radon-222 and nitrate-N concentrations) into the anoxic Upper Floridan aquifer (that contains low radon-222 and nitrate-N concentrations). Differences in arsenic concentrations in water from the various depth intervals in the public-supply well (3.2-19.0 micrograms per liter) were related to pumping conditions. The high arsenic

Homogeneous impact melts produced by a heterogeneous target?. Sr-Nd isotopic evidence from the Popigai crater, Russia

NASA Astrophysics Data System (ADS)

Kettrup, B.; Deutsch, A.; Masaitis, V. L.

The 35.7 ± 0.2 Ma old Popigai crater, Siberia, with a diameter of about 100 km is one of the best preserved large terrestrial impact structures. The heterogeneous target at the impact site consists of Archean to Lower Proterozoic metamorphic rocks of the crystalline basement, Upper Proterozoic quartzites and other clastic deposits, as well as Cambrian to Cretaceous clastic sediments and sedimentary rocks, including carbonate rocks. Moreover, Proterozoic and Permo-Triassic dolerite dykes are found in the target area. We report major element, Sr and Nd isotope data for 13 of these target rocks and for various types of impactites. The 15 analysed impactite samples include tagamites (impact melt rocks), suevites and impact glass from small veins. Furthermore, two impact breccias and two impact glass-coated gneiss bombs were analysed. We discuss the relation of these impactites to the target lithologies, and evaluate on the basis of literature data the relation of microkrystites (and associated microtektites) in Upper Eocene sediments to the Popigai event. The impactites have SiO 2 abundances ranging from 59 to 66 wt.% and show significant variations in the content of Fe, Ca, and Ti. They have present day 87Sr/ 86Sr ratios between 0.7191 and 0.7369. Their Sr model ages T SrUR range from 1.9 to 2.3 Ga. The 143Nd/ 144Nd ratios for the impactite samples cluster between 0.5113 and 0.5115. The Nd model ages T NdCHUR range from 1.9 to 2.1 Ga. In an ɛ CHUR(Nd)-ɛ UR(Sr) diagram, the impactites and Upper Eocene microkrystites (and associated microtektites) plot in a field delimited by Popigai target lithologies. The impactites are restricted to the field of crystalline basement rocks and Upper Proterozoic quartzites, but they show different isotopic signatures in different crater sectors. Impactites and Upper Eocene microkrystites plot in different, only partly overlapping clusters. The leucocratic microkrystites and microtektites have a higher affinity to the post-Proterozoic rocks in the target area than the impactites. Seemingly, the melanocratic microkrystites originated mostly from crystalline basement. This data alignment supports the assumption that Popigai is the source crater for all three types of ejecta. For the first time, clear relations are established of the geochemically variable Upper Eocene microkrystites and associated microtektites to specific target lithologies at Popigai crater. Finally, the observed range in Sr and Nd isotope parameters determined for impact melt lithologies that originated during the Popigai event show a much higher variability than known from other craters. This result indicates that mixing of impact melt which later formed tagamite sheets and glass particles in different impact breccias, was incomplete at the time of ejecta dispersal.

Computation of porosity redistribution resulting from thermal convection in slanted porous layers

NASA Astrophysics Data System (ADS)

Gouze, Phillippe; Coudrain-Ribstein, Anne; Bernard, Dominique

1994-01-01

Unlike fluid displacement due to regional hydraulic head, thermoconvetive motions are generally slow. The thermal impacts of such movements are very weak, whereas their chemical impacts may be significant because of their cumulated effects over geologic time. For nonhorizontal thick sedimentary reservoirs, the fluid velocity due to thermal convection can be accurately approximated by an explicit function of the dip of the reservior, the permeability and the difference in thermal conductivity between the aquifer and the confining beds. The latter parameter controls the rotation direction of the flow and, for clastic reservoirs bounded by impervious clayey media, fluid moves up the slope along the caprock layer. As the fluid velocity is small, the major rock-forming minerals control the fluid composition by thermodynamic equilibrium. Thus, whereas the volume of redistributed mineral depends on the volume of water circulated, the localization of porosity enhancement is strongly controlled by the reservoir mineralogy. With realistic values of permeability and layer thickness, several per cent of secondary porosity per million years can be created or lost at shallow depth (less than 2 km), depending on the chlorinity, the set of representative minerals and the temperature. In sandstone resevoirs and high-chlorinity calcarenite resoervoirs, the porosity decreases under the caprock where hydrocarbons can accumulate. In chlorinity calcarenite resevoirs, the porosity decreases under the caprock where hydrocarbons can accumulate. In chloride-depleted carbonate aquifers, the simulataneous control by carbonates, silica and aluminosilicates can produce a decrease of porosity above the bedrock and an enhancement of porosity under the caprock. However, computations show that the quality of the upper part of the reservoir is mainly reduced by the precipitation of silica and clays.

Interaction of the Siberian craton and Central Asian Orogenic Belt (CAOB) recorded by detrital zircons from Transbaikalia

NASA Astrophysics Data System (ADS)

Powerman, V.; Shatsillo, A.; Chumakov, N.; Kapitonov, I.; Hourigan, J. K.

2015-12-01

The goal of this study is to pinpoint the beginning of interaction of two gigantic crustal structures: the Siberian Craton and the Central Asian Orogenic Belt (CAOB). We hypothesize that the beginning of convergence should be recorded in the Neoproterozoic passive margin strata of Siberian Craton by the first appearance of extraregional Neoproterozoic zircons. In order to test this hypothesis, we have acquired U-Pb zircon age distributions from twelve Neoproterozoic clastic rocks from the Baikal-Patom margin of Siberia and one sample from the volcaniclastic Padrinsky Group that was deposited atop accreted CAOB crust. Stratigraphically lower strata from the Siberian margin yield Archean - Paleoproterozoic detrital zircon ages, which are similar to, and probably derived from the Siberian Precambrian craton. A few extra-regional Mesoproterozoic grains are also present. The provenance shift happens in the upper portion of the section and is marked by a strong influx of extra-regional Neoproterozoic sediments. The youngest grains of 610 Ma constrain the sedimentation age and confine the timing of interaction between CAOB and Siberia in this region. Neoproterozoic zircons also dominate the overlying sedimentary unit, suggesting the continuance of the convergence. The coeval volcanoclastic unit on the CAOB side has a similar U-Pb detrital age distribution, strengthening the provenance link. Analysis of the local tectonics suggests that the beginning of accretion might have started even before the first appearance of Neoproterozoic zircon: during the development of a regional unconformity, capped by 635 Ma (?) "Snowball Earth" tillites of Dzhemkukan Fm. The absence of Neoproterozoic zircons in Dzhemkukan Fm. is probably explained by a thin-skinned tectonics that did not result in massive orogenesis . Our data are in good correlation with other Neoproterozoic sedimentary basins of southern Siberian Craton, including Cisbaikalia and Bodaibo Synclinorium.

Erosion rates and landscape evolution of the lowlands of the Upper Paraguay river basin (Brazil) from cosmogenic 10Be

NASA Astrophysics Data System (ADS)

Pupim, Fabiano do Nascimento; Bierman, Paul R.; Assine, Mario Luis; Rood, Dylan H.; Silva, Aguinaldo; Merino, Eder Renato

2015-04-01

The importance of Earth's low sloping areas in regard to global erosion and sediment fluxes has been widely and vigorously debated. It is a crucial area of research to elucidate geologically meaningful rates of land-surface change and thus the speed of element cycling on Earth. However, there are large portions of Earth where erosion rates have not been well or extensively measured, for example, the tropical lowlands. The Cuiabana lowlands are an extensive low-altitude and low-relief dissected metamorphic terrain situated in the Upper Paraguay river basin, central-west Brazil. Besides exposures of highly variable dissected metamorphic rocks, flat residual lateritic caps related to a Late Cenozoic planation surface dominate interfluves of the Cuiabana lowlands. The timescale over which the lowlands evolved and the planation surface developed, and the rate at which they have been modified by erosion, are poorly known. Here, we present measurements of in situ produced cosmogenic 10Be in outcropping metamorphic bedrock and clastic-lateritic caps to quantify rates of erosion of the surface and associated landforms in order to better understand the Quaternary landscape evolution of these lowlands. Overall, slow erosion rates (mean 10 m/Ma) suggest a stable tectonic environment in these lowlands. Erosion rates vary widely between different lithologies (range 0.57 to 28.3 m/Ma) consistent with differential erosion driving regional landform evolution. The lowest erosion rates are associated with the low-relief area (irregular plains), where clastic-laterite (mean 0.67 m/Ma) and quartzite (mean 2.6 m/Ma) crop out, whereas the highest erosion rates are associated with dissection of residual hills, dominated by metasandstone (mean 11.6 m/Ma) and phyllite (mean 27.6 m/Ma). These data imply that the Cuiabana lowland is comprised of two dominant landform sets with distinct and different dynamics. Because the planation surface (mostly lowlands) is lowering and losing mass more slowly than associated residual hills, regional relief is decreasing over time and the landscape is not in steady state. The extremely slow erosion rates of the clastic-laterite are similar to the slowest outcrop erosion rates reported worldwide. These slow rates are due to the material's properties and resistance, being comprised of quartzite fragments cemented by an iron-rich crust, and reflecting long-term weathering with iron chemical precipitation and ferricrete formation, at least since the Middle Pleistocene. The lateritic caprock appears to be a key factor maintaining hilltop summits of the planation surface over long timescales.

Geologic summary of the Appalachian Basin, with reference to the subsurface disposal of radioactive waste solutions

USGS Publications Warehouse

Colton, G.W.

1962-01-01

The Appalachian basin is an elongate depression in the crystalline basement complex< which contains a great volume of predominantly sedimentary stratified rocks. As defined in this paper it extends from the Adirondack Mountains in New York to central Alabama. From east to west it extends from the west flank of the Blue Ridge Mountains to the crest of the Findlay and Cincinnati arches and the Nashville dome. It encompasses an area of about 207,000 square miles, including all of West Virginia and parts of New York, New Jersey, Pennsylvania, Ohio, Maryland, Virginia, Kentucky, Tennessee, North Carolina, Georgia, and Alabama. The stratified rocks that occupy the basin constitute a wedge-shaped mass whose axis of greatest thickness lies close to and parallel to the east edge of the basin. The maximum thickness of stratified rocks preserved in any one part of the basin today is between 35,000 and 40,000 feet. The volume of the sedimentary rocks is approximately 510,000 cubic miles and of volcanic rocks is a few thousand cubic miles. The sedimentary rocks are predominantly Paleozoic in age, whereas the volcanic rocks are predominantly Late Precambrian. On the basis of gross lithology the stratified rocks overlying the crystalline basement complex can be divided into nine vertically sequential units, which are designated 'sequences' in this report. The boundaries between contiguous sequences do not necessarily coincide with the commonly recognized boundaries between systems or series. All sequences are grossly wedge shaped, being thickest along the eastern margin of the basin and thinnest along the western margin. The lowermost unit--the Late Precambrian stratified sequence--is present only along part of the eastern margin of the basin, where it lies unconformably on the basement complex. It consists largely of volcanic tuffs and flows but contains some interbedded sedimentary rocks. The Late Precambrian sequence is overlain by the Early Cambrian clastic sequence. Where the older sequence is absent, the Early Cambrian sequence rests on the basement complex. Interbedded fine- to coarse-grained noncarbonate detrital rocks comprise the bulk of the sequence, but some volcanic and carbonate rocks are included. Next above is the Cambrian-Ordovician carbonate sequence which consists largely of limestone and dolomite. Some quartzose sandstone is present in the lower part in the western half of the basin, and much shale is present in the upper part in the southeast part of the basin. The next higher sequence is the Late Ordovician clastic sequence, which consists largely of shale, siltstone, and sandstone. Coarse-grained light-gray to red rocks are common in the sequence along the eastern side of the basin, whereas fine-grained dark-gray to black calcareous rocks are common along the west side. The Late Ordovician clastic sequence is overlain--unconformably in many places--by the Early Silurian clastic sequence. The latter comprises a relatively thin wedge of coarse-grained clastic rocks. Some of the most prolific oil- and gas-producing sandstones in the Appalachian basin are included. Among these are the 'Clinton' sands of Ohio, the Medina Sandstones of New York and Pennsylvania, and the Keefer or 'Big Six' Sandstone of West Virginia and Kentucky. Conformably overlying the Early Silurian clastic sequence is the Silurian-Devonian carbonate sequence, which consists predominantly of limestone and dolomite. It also contains a salt-bearing unit in the north-central part of the basin and a thick wedge of coarse-grained red beds in the northeastern part. The sequence is absent in much of the southern part of the basin. Large volumes of gas and much oil are obtained from some of its rocks, especially from the Oriskany Sandstone and the Huntersville Chert. The Silurian-Devonian carbonate sequence is abruptly overlain by the Devonian clastic sequence--a thick succession of interbedded shale, mudrock, siltstone, and sandstone. Colors range f

Petroleum geology and resources of the North Caspian Basin, Kazakhstan and Russia

USGS Publications Warehouse

Ulmishek, Gregory F.

2001-01-01

The North Caspian basin is a petroleum-rich but lightly explored basin located in Kazakhstan and Russia. It occupies the shallow northern portion of the Caspian Sea and a large plain to the north of the sea between the Volga and Ural Rivers and farther east to the Mugodzhary Highland, which is the southern continuation of the Ural foldbelt. The basin is bounded by the Paleozoic carbonate platform of the Volga-Ural province to the north and west and by the Ural, South Emba, and Karpinsky Hercynian foldbelts to the east and south. The basin was originated by pre-Late Devonian rifting and subsequent spreading that opened the oceanic crust, but the precise time of these tectonic events is not known. The sedimentary succession of the basin is more than 20 km thick in the central areas. The drilled Upper Devonian to Tertiary part of this succession includes a prominent thick Kungurian (uppermost Lower Permian) salt formation that separates strata into the subsalt and suprasalt sequences and played an important role in the formation of oil and gas fields. Shallow-shelf carbonate formations that contain various reefs and alternate with clastic wedges compose the subsalt sequence on the 1 basin margins. Basinward, these rocks grade into deep-water anoxic black shales and turbidites. The Kungurian salt formation is strongly deformed into domes and intervening depressions. The most active halokinesis occurred during Late Permian?Triassic time, but growth of salt domes continued later and some of them are exposed on the present-day surface. The suprasalt sequence is mostly composed of clastic rocks that are several kilometers thick in depressions between salt domes. A single total petroleum system is defined in the North Caspian basin. Discovered reserves are about 19.7 billion barrels of oil and natural gas liquids and 157 trillion cubic feet of gas. Much of the reserves are concentrated in the supergiant Tengiz, Karachaganak, and Astrakhan fields. A recent new oil discovery on the Kashagan structure offshore in the Caspian Sea is probably also of the supergiant status. Major oil and gas reserves are located in carbonate reservoirs in reefs and structural traps of the subsalt sequence. Substantially smaller reserves are located in numerous fields in the suprasalt sequence. These suprasalt fields are largely in shallow Jurassic and Cretaceous clastic reservoirs in salt dome-related traps. Petroleum source rocks are poorly identified by geochemical methods. However, geologic data indicate that the principal source rocks are Upper Devonian to Lower Permian deep-water black-shale facies stratigraphically correlative to shallow-shelf carbonate platforms on the basin margins. The main stage of hydrocarbon generation was probably in Late Permian and Triassic time, during deposition of thick orogenic clastics. Generated hydrocarbons migrated laterally into adjacent subsalt reservoirs and vertically, through depressions between Kungurian salt domes where the salt is thin or absent, into suprasalt clastic reservoirs. Six assessment units have been identified in the North Caspian basin. Four of them include Paleozoic subsalt rocks of the basin margins, and a fifth unit, which encompasses the entire total petroleum system area, includes the suprasalt sequence. All five of these assessment units are underexplored and have significant potential for new discoveries. Most undiscovered petroleum resources are expected in Paleozoic subsalt carbonate rocks. The assessment unit in subsalt rocks with the greatest undiscovered potential occupies the south basin margin. Petroleum potential of suprasalt rocks is lower; however, discoveries of many small to medium size fields are expected. The sixth identified assessment unit embraces subsalt rocks of the central basin areas. The top of subsalt rocks in these areas occurs at depths ranging from 7 to 10 kilometers and has not been reached by wells. Undiscovered resources of this unit did not rec

Nano scale dynamics of bubble nucleation in confined liquid subjected to rapid cooling: Effect of solid-liquid interfacial wettability

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Rabbi, Kazi Fazle; Mukut, K. M.; Tamim, Saiful Islam; Faisal, A. H. M.

2017-06-01

This study focuses on the occurrence of bubble nucleation in a liquid confined in a nano scale confinement and subjected to rapid cooling at one of its wall. Due to the very small size scale of the present problem, we adopt the molecular dynamics (MD) approach. The liquid (Argon) is confined within two solid (Platinum) walls. The temperature of the upper wall of the confinement is maintained at 90 K while the lower wall is being cooled rapidly to 50 K from initial equilibrium temperature of 90 K within 0.1 ns. This results in the nucleation and formation of nanobubbles in the liquid. The pattern of bubble nucleation has been studied for three different conditions of solid-liquid interfacial wettability such as hydrophilic, hydrophobic and neutral. Behavior of bubble nucleation is significantly different in the three case of solid-liquid interfacial wettability. In case of the hydrophobic confinement (weakly adsorbing), the liquid cannot achieve deeper metastability; vapor layers appear immediately on the walls. In case of the neutral confinement (moderately adsorbing), bubble nucleation is promoted by the walls where the nucleation is heterogeneous. In case of the hydrophilic walls (strongly adsorbing) bubbles are developed inside the liquid; that is the nucleation process is homogeneous. The variation in bubble nucleation under different conditions of surface wettability has been studied by the analysis of number density distribution, spatial temperature distribution, spatial number density distribution and heat flux through the upper and lower walls of the confinement. The present study indicates that the variation of heat transfer efficiency due to different surface wettability has significant effect on the size, shape and location of bubble nucleation in case rapid cooling of liquid in nano confinement.

Geohydrologic data from Port Royal Sound, Beaufort County, South Carolina

USGS Publications Warehouse

Burt, R.A.; Belval, D.L.; Crouch, Michael; Hughes, W.B.

1986-01-01

Nine offshore wells were drilled through overlying sediments into the Upper Floridan aquifer in Port Royal Sound, South Carolina and the adjacent Atlantic Ocean, to obtain geologic, hydrologic, and water quality data. The Upper Floridan aquifer consists predominantly of light-gray, poorly consolidated, fossiliferous limestone. In the Port Royal Sound area, the Upper Floridan is overlain by olive-gray, medium to course sand and silty sand. Falling-head permeability tests on these overlying clastic sediments indicate permeabilities of 1,100 to 4.3 x 10 to the 7th power centimeters/sec. Other geologic and hydrologic data, including geophysical logs, sieve analyses, and detailed core descriptions were obtained, along with continuous water level records of the wells, tidal records, and barometric pressure records. Water collected from the Upper Floridan aquifer beneath Port Royal Sound and the ocean ranged in concentration of chloride from 54 to 12,000 mg/l. Measured pH ranged from 6.8 to 8.4, and alkalinity ranged from 122 to 368 mg/l as CaC03. Other water quality data obtained include temperature, specific conductance, carbon-13, carbon-14, tritium , deuterium, oxygen-18, dissolved oxygen, dissolved solids, nitrogen species, phosphorus, organic carbon, cyanide, sulfide, calcium, magnesium, sodium, potassium, sulfate, fluoride, silica , bromide, iodide, and selected trace metals. (USGS)

Magnetic susceptibility as an indicator to paleo-environmental pollution in an urban lagoon near Istanbul city

NASA Astrophysics Data System (ADS)

Alpar, Bedri; Unlu, Selma; Altinok, Yildiz; Ongen, Sinan

2014-05-01

For assessing anthropogenic pollution, magnetic susceptibility profiles and accompanying data were measured along three short cores recovered at the southern part of an urban lagoon; Kucukcekmece, Istanbul, Turkey. This marine inlet, connected to the Sea of Marmara by a very narrow channel, was used as a drinking water reservoir 40-50 years ago before it was contaminated by municipal, agricultural and industrial activities, mainly carried by three streams feeding the lagoon. The magnetic signals decrease gradually from the lake bottom towards the core base showing some characteristic anomalies. These signatures were tested as an environmental magnetic parameter against the lithological diversity (silici-clastic, total organic matter and carbonate), metal enrichments with larger variations (Pb, Mn, Zn, Ni, Co, Cr, U and Al) and probable hydrocarbon contamination. Mineral assemblage was determined by a computer driven X-ray diffractometer. The heavy metal concentrations and total petroleum hydrocarbons (TPH) were measured by ICP-MS and UVF spectrometry, respectively. Magnetic susceptibility shows slightly higher values in interlayers containing higher silici-clastic material and organic content which may suggest first-order changes in the relative supplies of terrigenous and biogenic materials. On the basis of cluster analyses, enhanced magnetic signals could be correlated with the elevated concentrations of Co, Zn, U, Pb and TPH along the cores. The Pb concentrations at the upper parts of the cores were higher than the "Severe Effect Level" and could pose a potential risk for living organisms. Greater amounts of organic carbon tend to accumulate in muddy sediments. In fact, there are a few studies reporting some relationship between enhanced magnetic signals and organic contamination mainly due to petroleum aromatic hydrocarbons. In conclusion, the magnetic susceptibility changes in sedimentary depositional environments could be used as a rapid and cost-effective tool in identification of silici-clastic content, enrichment of some metals (iron cycling and bacterial activity) and increased TPH concentrations in hydrocarbon contaminated sediments along the cores.

Petroleum geology and resources of the West Siberian Basin, Russia

USGS Publications Warehouse

Ulmishek, Gregory F.

2003-01-01

The West Siberian basin is the largest petroleum basin in the world covering an area of about 2.2 million km2. The basin occupies a swampy plain between the Ural Mountains and the Yenisey River. On the north, the basin extends offshore into the southern Kara Sea. On the west, north, and east, the basin is surrounded by the Ural, Yenisey Ridge, and Turukhan-Igarka foldbelts that experienced major deformations during the Hercynian tectonic event and the Novaya Zemlya foldbelt that was deformed in early Cimmerian (Triassic) time. On the south, the folded Caledonian structures of the Central Kazakhstan and Altay-Sayan regions dip northward beneath the basin?s sedimentary cover. The basin is a relatively undeformed Mesozoic sag that overlies the Hercynian accreted terrane and the Early Triassic rift system. The basement is composed of foldbelts that were deformed in Late Carboniferous?Permian time during collision of the Siberian and Kazakhstan continents with the Russian craton. The basement also includes several microcontinental blocks with a relatively undeformed Paleozoic sedimentary sequence. The sedimentary succession of the basin is composed of Middle Triassic through Tertiary clastic rocks. The lower part of this succession is present only in the northern part of the basin; southward, progressively younger strata onlap the basement, so that in the southern areas the basement is overlain by Toarcian and younger rocks. The important stage in tectono-stratigraphic development of the basin was formation of a deep-water sea in Volgian?early Berriasian time. The sea covered more than one million km2 in the central basin area. Highly organic-rich siliceous shales of the Bazhenov Formation were deposited during this time in anoxic conditions on the sea bottom. Rocks of this formation have generated more than 80 percent of West Siberian oil reserves and probably a substantial part of its gas reserves. The deep-water basin was filled by prograding clastic clinoforms during Neocomian time. The clastic material was transported by a system of rivers dominantly from the eastern provenance. Sandstones within the Neocomian clinoforms contain the principal oil reservoirs. The thick continental Aptian?Cenomanian Pokur Formation above the Neocomian sequence contains giant gas reserves in the northern part of the basin. Three total petroleum systems are identified in the West Siberian basin. Volumes of discovered hydrocarbons in these systems are 144 billion barrels of oil and more than 1,300 trillion cubic feet of gas. The assessed mean undiscovered resources are 55.2 billion barrels of oil, 642.9 trillion cubic feet of gas, and 20.5 billion barrels of natural gas liquids. The largest known oil reserves are in the Bazhenov-Neocomian total petroleum system that includes Upper Jurassic and younger rocks of the central and southern parts of the basin. Oil reservoirs are mainly in Neocomian and Upper Jurassic clastic strata. Source rocks are organic-rich siliceous shales of the Bazhenov Formation. Most discovered reserves are in structural traps, but stratigraphic traps in the Neocomian clinoform sequence are pro-ductive and are expected to contain much of the undiscovered resources. Two assessment units are identified in this total petroleum system. The first assessment unit includes all conventional reservoirs in the stratigraphic interval from the Upper Jurassic to the Cenomanian. The second unit includes unconventional (or continuous), self-sourced, fractured reservoirs in the Bazhenov Formation. This unit was not assessed quantitatively. The Togur-Tyumen total petroleum system covers the same geographic area as the Bazhenov-Neocomian system, but it includes older, Lower?Middle Jurassic strata and weathered rocks at the top of the pre-Jurassic sequence. A Callovian regional shale seal of the Abalak and lower Vasyugan Formations separates the two systems. The Togur-Tyumen system is oil-prone; gas reserves are insignificant. The principal o

Petroleum geology and resources of the Dnieper-Donets Basin, Ukraine and Russia

USGS Publications Warehouse

Ulmishek, Gregory F.

2001-01-01

The Dnieper-Donets basin is almost entirely in Ukraine, and it is the principal producer of hydrocarbons in that country. A small southeastern part of the basin is in Russia. The basin is bounded by the Voronezh high of the Russian craton to the northeast and by the Ukrainian shield to the southwest. The basin is principally a Late Devonian rift that is overlain by a Carboniferous to Early Permian postrift sag. The Devonian rift structure extends northwestward into the Pripyat basin of Belarus; the two basins are separated by the Bragin-Loev uplift, which is a Devonian volcanic center. Southeastward, the Dnieper-Donets basin has a gradational boundary with the Donbas foldbelt, which is a structurally inverted and deformed part of the basin. The sedimentary succession of the basin consists of four tectono-stratigraphic sequences. The prerift platform sequence includes Middle Devonian to lower Frasnian, mainly clastic, rocks that were deposited in an extensive intracratonic basin. 1 The Upper Devonian synrift sequence probably is as thick as 4?5 kilometers. It is composed of marine carbonate, clastic, and volcanic rocks and two salt formations, of Frasnian and Famennian age, that are deformed into salt domes and plugs. The postrift sag sequence consists of Carboniferous and Lower Permian clastic marine and alluvial deltaic rocks that are as thick as 11 kilometers in the southeastern part of the basin. The Lower Permian interval includes a salt formation that is an important regional seal for oil and gas fields. The basin was affected by strong compression in Artinskian (Early Permian) time, when southeastern basin areas were uplifted and deeply eroded and the Donbas foldbelt was formed. The postrift platform sequence includes Triassic through Tertiary rocks that were deposited in a shallow platform depression that extended far beyond the Dnieper-Donets basin boundaries. A single total petroleum system encompassing the entire sedimentary succession is identified in the Dnieper-Donets basin. Discovered reserves of the system are 1.6 billion barrels of oil and 59 trillion cubic feet of gas. More than one-half of the reserves are in Lower Permian rocks below the salt seal. Most of remaining reserves are in upper Visean-Serpukhovian (Lower Carboniferous) strata. The majority of discovered fields are in salt-cored anticlines or in drapes over Devonian horst blocks; little exploration has been conducted for stratigraphic traps. Synrift Upper Devonian carbonate reservoirs are almost unexplored. Two identified source-rock intervals are the black anoxic shales and carbonates in the lower Visean and Devonian sections. However, additional source rocks possibly are present in the deep central area of the basin. The role of Carboniferous coals as a source rock for gas is uncertain; no coal-related gas has been identified by the limited geochemical studies. The source rocks are in the gas-generation window over most of the basin area; consequently gas dominates over oil in the reserves. Three assessment units were identified in the Dnieper-Donets Paleozoic total petroleum system. The assessment unit that contains all discovered reserves embraces postrift Carboniferous and younger rocks. This unit also contains the largest portion of undiscovered resources, especially gas. Stratigraphic and combination structural and stratigraphic traps probably will be the prime targets for future exploration. The second assessment unit includes poorly known synrift Devonian rocks. Carbonate reef reservoirs along the basin margins probably will contain most of the undiscovered resources. The third assessment unit is an unconventional, continuous, basin-centered gas accumulation in Carboniferous low-permeability clastic rocks. The entire extent of this accumulation is unknown, but it occupies much of the basin area. Resources of this assessment unit were not estimated quantitatively.

Repeated fault rupture recorded by paleoenvironmental changes in a wetland sedimentary sequence ponded against the Alpine Fault, New Zealand

NASA Astrophysics Data System (ADS)

Clark, K.; Berryman, K. R.; Cochran, U. A.; Bartholomew, T.; Turner, G. M.

2010-12-01

At Hokuri Creek, in south Westland, New Zealand, an 18 m thickness of Holocene sediments has accumulated against the upthrown side of the Alpine Fault. Recent fluvial incision has created numerous exposures of this sedimentary sequence. At a decimetre to metre scale there are two dominant types of sedimentary units: clastic-dominated, grey silt packages, and organic-dominated, light brown peaty-silt units. These units represent repeated alternations of the paleoenvironment due to fault rupture over the past 7000 years. We have located the event horizons within the sedimentary sequence, and identified evidence to support earthquake-driven paleoenvironmental change (rather than climatic variability), and developed a model of paleoenvironmental changes over a typical seismic cycle. To quantitatively characterise the sediments we use high resolution photography, x-ray imaging, magnetic-susceptibility and total carbon analysis. To understand the depositional environment we used diatom and pollen studies. The organic-rich units have very low magnetic susceptibility and density values, with high greyscale and high total carbon values. Diatoms indicate these units represent stable wetland environments with standing water and predominantly in-situ organic material deposition. The clastic-rich units are characterised by higher magnetic susceptibility and density values, with low greyscale and total carbon. The clastic-rich units represent environments of flowing water and deep pond settings that received predominantly catchment-derived silt and sand. The event horizon is located at the upper contact of the organic-rich horizons. The event horizon contact marks a drastic change in hydrologic regime as fault rupture changed the stream base level and there was a synchronous influx of clastic sediment as the catchment responded to earthquake shaking. During the interseismic period the flowing-water environment gradually stabilised and returned to an organic-rich wetland. Such cycles were repeated 18 times at Hokuri Creek. Evidence that fault rupture was responsible for the cyclical paleoenvironmental changes at Hokuri Creek include: the average time period for each organic- and clastic-rich couplet to be deposited approximately equals the long-term average Alpine Fault recurrence interval, and the most recent events recorded at Hokuri correlate to an earthquake dated in paleoseismic trenches 100 km along strike; fault rupture is the only mechanism that can create accommodation space for 18 m of sediment to accumulate, and the sedimentary units can be traced from the outcrop to the fault trace and show tectonic deformation. The record of 18 fault rupture events at Hokuri Creek is one of the longest records of surface ruptures on a major plate boundary fault. High-resolution dating and statistical treatment of the radiocarbon data (Biasi et al., this meeting) has resulted in major advances in understanding the long-term behaviour of the Alpine Fault (Berryman et al., this meeting).

The Middle Jurassic microflora from El Maghara N° 4 borehole, Northern Sinai, Egypt

NASA Astrophysics Data System (ADS)

Mohsen, Sayed Abdel

The coal bearing formation in El Maghara area, northern Sinai, yielded abundant, diverse and generally well preserved spores, pollen and marine microflora. The palynological analysis of the fine clastic sediments in this formation yielded (71) species related to (44) genera. Three different palynological assemblage zones can be distinguished. The sediments which contain lower and the upper assemblage zones bearing the coal seems, were deposited in non-marine (swamp) environment. In the middle assemblage zone few marine microflora can be identified, indicating a coastal near shore marine environment. Compared with other palynologic data obtained from Egypt and other countries, the three described assemblage zones belong to Middle Jurassic (Bathonian) age.

29 CFR Appendix A to Subpart B of... - Compliance Assistance Guidelines for Confined and Enclosed Spaces and Other Dangerous Atmospheres

Code of Federal Regulations, 2010 CFR

2010-07-01

... interchangeably in fire science literature. Section 1915.11(b)Definition of “Upper explosive limit.” The terms upper flammable limit (UFL) and upper explosive limit (UEL) are used interchangeably in fire science... life and is adequate for entry. However, any oxygen level greater than 20.8 percent by volume should...

29 CFR Appendix A to Subpart B of... - Compliance Assistance Guidelines for Confined and Enclosed Spaces and Other Dangerous Atmospheres

Code of Federal Regulations, 2011 CFR

2011-07-01

... interchangeably in fire science literature. Section 1915.11(b)Definition of “Upper explosive limit.” The terms upper flammable limit (UFL) and upper explosive limit (UEL) are used interchangeably in fire science... life and is adequate for entry. However, any oxygen level greater than 20.8 percent by volume should...

Hydrogeologic framework and geologic structure of the Floridan aquifer system and intermediate confining unit in the Lake Okeechobee area, Florida

USGS Publications Warehouse

Reese, Ronald S.

2014-01-01

The successful implementation of aquifer storage and recovery (ASR) as a water-management tool requires detailed information on the hydrologic and hydraulic properties of the potential water storage zones. This report presents stratigraphic and hydrogeologic sections of the upper part of the Floridan aquifer system and the overlying confining unit or aquifer system in the Lake Okeechobee area, and contour maps of the upper contacts of the Ocala Limestone and the Arcadia Formation, which are represented in the sections. The sections and maps illustrate hydrogeologic factors such as confinement of potential storage zones, the distribution of permeability within the zones, and geologic features that may control the efficiency of injection, storage, and recovery of water, and thus may influence decisions on ASR activities in areas of interest to the Comprehensive Everglades Restoration Plan.

Karst connections between unconfined aquifers and the Upper Floridan aquifer in south Georgia: geophysical evidence and hydrogeological models

NASA Astrophysics Data System (ADS)

Thieme, D. M.; Denizman, C.

2011-12-01

Buried karst features in sedimentary rocks of the south Georgia Coastal Plain present a challenge for hydrogeological models of recharge and confined flow within the underlying Upper Floridan aquifer. The Withlacoochee River, the trunk stream for the area, frequently disappears into subsurface caverns as it makes its way south to join the Suwannee River in northern Florida. The Withlacoochee also receives inputs from small ponds and bays which in turn receive spring and seep groundwater inputs. We have mapped karst topography at the "top of rock" using ground-penetrating radar (GPR). Up to seven meters of relief is indicated for the paleotopography on Miocene to Pliocene rocks, contrasting with the more subdued relief of the modern landscape. Current stratigraphic and hydrogeological reconstructions do not incorporate this amount of relief or lateral variation in the confining beds. One "pipe" which is approximately four meters in diameter is being mapped in detail. We have field evidence at this location for rapid movement of surficial pond and river water with a meteoric signature through several separate strata of sedimentary rock into an aquifer in the Hawthorn formation. We use our geophysical and hydrological field evidence to constrain quantitative hydrogeological models for the flow rates into and out of both this upper aquifer and the underlying Upper Floridan aquifer, which is generally considered to be confined by the clays of the Hawthorn.

Sedimentology and genetic stratigraphy of Dean and Spraberry Formations (Permian), Midland basin, Texas

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

Handford, C.R.

1981-09-01

The Spraberry trend of west Texas, once known as the world's largest uneconomic oil field, will undoubtedly become an increasingly important objective for the development of enhanced oil recovery techniques in fine-grained, low-permeability, low-pressure reservoirs. As the trend expands, facies and stratigraphic data should be integrated into exploration strategies. The Spraberry and Dean Formations may be divided into three genetic sequences, each consisting of several hundred feet of interbedded shale and carbonate overlain by a roughly equal amount of sandstone and siltstone. These sequences record episodes of shelf-margin progradation, deep-water resedimentation of shelf-derived carbonate debris, followed by influxes of terrigenousmore » clastics into the basin by way of feeder channels or submarine canyons, and suspension settling of fine-grained sediment from the water column. Four lithofacies comprise the terrigenous clastics of the Spraberry and Dean Fomations: (1) cross-laminated, massive, and parallel-laminated sandstone, (2) laminated siltstone, (3) bioturbated siltstone, and (4) black, organic-rich shale. Carbonate lithofacies occur mostly in the form of thin-bedded turbidites, slump, and debris-flow deposits. Terrigenous clastic rocks display facies sequences, isopach patterns, and sedimentary structures suggestive of deposition from turbidity currents, and long-lived saline density underflow and interflow currents. Clastic isopach patterns reflect an overall southward thinning of clastics in the Midland basin. Channelized flow and suspension settling were responsible for the formation of elongate fan-shaped accumulations of clastic sediments.« less

Proceedings of the Ground-Water Detection Workshop Held at Vicksburg, Mississippi on 12-14 January 1982.

DTIC Science & Technology

1984-12-01

shales and hard aquiferic car- bonates. Therefore, small confined and perched aquifers can occur in a number of localities. The basement complex...the region that extends from Saudia Arabia all the way into Algeria, Morocco, and Tunisia is from older to younger strata. The major aquifer in the... aquifers all the way down the stratigraphic section--a phreatic one at the top, then semi- confined and confined aquifers until we get to upper

Age and correlation of tertiary sediments in the western South Carolina Coastal Plain

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

Laws, R.A.; Harris, W.B.; Zullo, V.A.

1987-01-01

Integration of coastal onlap stratigraphy, calcareous nannofossil, dinoflagellate, and megafossil biostratigraphy provide new data for interpretation of age and interregional correlation of Paleocene to Oligocene deposits of the western South Carolina Coastal Plain. Clastic and calcareous sediments examined in cores and outcrops in the vicinity of the Savannah River Plant record at least seven coastal onlap cycles. Basal Tertiary sediments of the Ellenton Formation represent cycles TA1.1 - 1.3 and contain dinoflagellates of Midwayan to Sabinian age. The overlying Williamsburg Formation probably represents deposits of cycle TA2.1. The superjacent siliciclastics of the Congaree Formation contain few fossils, but may preservemore » transgressive and highstand deposits of cycles TA2.4 - 3.3. The overlying unit is commonly calcareous, contains nannofossils indicative of zones NP16-17 (Upper Claibornian), and marks a significant change in depositional style subsequent to the 49.5 Ma eustatic fall. ''Marls'' of the overlying Griffins Landing Member of the Dry Branch Formation contain micro- and megafossils of Late Eocene (Jacksonian) age and represent transgressive deposits of cycle TA4.1. The discontinuous lateral distribution of these calcareous units and overlying clastics of the Dry Branch and Tobacco Road Formations results largely from erosion and deep incision during the mid-Oligocene eustatic fall (30 Ma). The ''Upland'' unit is interpreted as being deposited on this erosional surface.« less

Multi-scale constraints of sediment source to sink systems in frontier basins: a forward stratigraphic modeling case study of the Levant region

NASA Astrophysics Data System (ADS)

Hawie, Nicolas; Deschamps, Remy; Granjeon, Didier; Nader, Fadi-Henri; Gorini, Christian; Müller, Carla; Montadert, Lucien; Baudin, François

2015-04-01

Recent scientific work underlined the presence of a thick Cenozoic infill in the Levant Basin reaching up to 12 km. Interestingly; restricted sedimentation was observed along the Levant margin in the Cenozoic. Since the Late Eocene successive regional geodynamic events affecting Afro-Arabia and Eurasia (collision and strike slip deformation)induced fast marginal uplifts. The initiation of local and long-lived regional drainage systems in the Oligo-Miocene period (e.g. Lebanon versus Nile) provoked a change in the depositional pattern along the Levant margin and basin. A shift from carbonate dominated environments into clastic rich systems has been observed. Through this communication we explore the importance of multi-scale constraints (i.e.,seismic, well and field data) in the quantification of the subsidence history, sediment transport and deposition of a Middle-Upper Miocene "multi-source" to sink system along the northernLevant frontier region. We prove through a comprehensive forward stratigraphic modeling workflow that the contribution to the infill of the northern Levant Basin (offshore Lebanon) is split in between proximal and more distal clastic sources as well as in situ carbonate/hemipelagic deposition. In a wider perspective this work falls under the umbrella of multi-disciplinary source to sink studies that investigate the impact of geodynamic events on basin/margin architectural evolutions, consequent sedimentary infill and thus on petroleum systems assessment.

Magnetotelluric Data, Rainier Mesa/Shoshone Mountain, Nevada Test Site, Nevada.

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

Jackie M. Williams; Jay A. Sampson; Brian D. Rodriguez

2006-11-03

The United States Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) at their Nevada Site Office (NSO) are addressing ground-water contamination resulting from historical underground nuclear testing through the Environmental Management (EM) program and, in particular, the Underground Test Area (UGTA) project. From 1951 to 1992, 828 underground nuclear tests were conducted at the Nevada Test Site northwest of Las Vegas. Most of these tests were conducted hundreds of feet above the ground-water table; however, more than 200 of the tests were near or within the water table. This underground testing was limited to specific areas ofmore » the Nevada Test Site, including Pahute Mesa, Rainier Mesa/Shoshone Mountain, Frenchman Flat, and Yucca Flat. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology, and its effects on ground-water flow. Ground-water modelers would like to know more about the hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Rainier Mesa/Shoshone Mountain Corrective Action Unit (Bechtel Nevada, 2006). During 2005, the U.S. Geological Survey (USGS), in cooperation with the DOE and NNSA-NSO, collected and processed data from twenty-six magnetotelluric (MT) and audio-magnetotelluric (AMT) sites at the Nevada Test Site. The 2005 data stations were located on and near Rainier Mesa and Shoshone Mountain to assist in characterizing the pre-Tertiary geology in those areas. These new stations extend the area of the hydrogeologic study previously conducted in Yucca Flat. This work will help refine what is known about the character, thickness, and lateral extent of pre-Tertiary confining units. In particular, a major goal has been to define the upper clastic confining unit (UCCU – late Devonian to Mississippian-age siliciclastic rocks assigned to the Eleana Formation and Chainman Shale) from the Yucca Flat area and west towards Shoshone Mountain, to Buckboard Mesa in the south, and onto Rainier Mesa in the north. Subsequent interpretation will include a three-dimensional (3-D) character analysis and a two-dimensional (2-D) resistivity model. The purpose of this report is to release the MT sounding data for the twenty-six stations shown in figure 1. No interpretation of the data is included here.« less

Revised geologic cross sections of parts of the Colorado, White River, and Death Valley regional groundwater flow systems, Nevada, Utah, and Arizona

USGS Publications Warehouse

Page, William R.; Scheirer, Daniel S.; Langenheim, V.E.; Berger, Mary A.

2006-01-01

This report presents revisions to parts of seven of the ten cross sections originally published in U.S. Geological Survey Open-File Report 2006-1040. The revisions were necessary to correct errors in some of the original cross sections, and to show new parts of several sections that were extended and (or) appended to the original section profiles. Revisions were made to cross sections C-C', D-D', E-E', F-F', G-G', I-I', and J-J', and the parts of the sections revised or extended are highlighted below the sections on plate 1 by red brackets and the word "revised," or "extended." Sections not listed above, as well as the interpretive text and figures, are generally unchanged from the original report. Cross section C-C' includes revisions in the east Mormon Mountains in the east part of the section; D-D' includes revisions in the Mormon Mesa area in the east part of the section; E-E' includes revisions in the Muddy Mountains in the east part of the section; F-F' includes revisions from the Muddy Mountains to the south Virgin Mountains in the east part of the section; and J-J' includes some revisions from the east Mormon Mountains to the Virgin Mountains. The east end of G-G' was extended about 16 km from the Black Mountains to the southern Virgin Mountains, and the northern end of I-I' was extended about 45 km from the Muddy Mountains to the Mormon Mountains, and revisions were made in the Muddy Mountains part of the original section. This report contains 10 interpretive cross sections and an integrated text describing the geology of parts of the Colorado, White River, and Death Valley regional groundwater flow systems in Nevada, Utah, and Arizona. The primary purpose of the report is to provide geologic framework data for input into a numerical groundwater model. Therefore, the stratigraphic and structural summaries are written in a hydrogeologic context. The oldest rocks (basement) are Early Proterozoic metamorphic and intrusive crystalline rocks that are considered confining units because of their low permeability. Late Proterozoic to Lower Cambrian clastic units overlie the crystalline rocks and are also considered confining units within the regional flow systems. Above the clastic units are Middle Cambrian to Lower Permian carbonate rocks that are the primary aquifers in the flow systems. The Middle Cambrian to Lower Permian carbonate rocks are overlain by a sequence of mainly clastic rocks of late Paleozoic to Mesozoic age that are mostly considered confining units, but they may be permeable where faulted. Tertiary volcanic and plutonic rocks are exposed in the northern and southern parts of the study area. In the Clover and Delamar Mountains, these rocks are highly deformed by north- and northwest-striking normal and strike-slip faults that are probably important conduits in transmitting groundwater from the basins in the northern Colorado and White River flow systems to basins in the southern part of the flow systems. The youngest rocks in the region are Tertiary to Quaternary basin-fill deposits. These rocks consist of middle to late Tertiary sediments consisting of limestone, conglomerate, sandstone, tuff, and gypsum, and younger Quaternary surficial units consisting of alluvium, colluvium, playa deposits, and eolian deposits. Basin-fill deposits are both aquifers and aquitards. The rocks in the study area were complexly deformed by episodes of Mesozoic compression and Cenozoic extensional tectonism. Some Cretaceous thrust faults and folds of the Sevier orogenic belt form duplex zones and define areas of maximum thickness for the Paleozoic carbonate rocks. Cenozoic faults are important because they are the primary structures that control groundwater flow in the regional flow systems.

Comment on “An unconfined groundwater model of the Death Valley Regional Flow System and a comparison to its confined predecessor” by R.W.H. Carroll, G.M. Pohll and R.L. Hershey [Journal of Hydrology 373/3–4, pp. 316–328

USGS Publications Warehouse

Faunt, Claudia C.; Provost, Alden M.; Hill, Mary C.; Belcher, Wayne R.

2011-01-01

Carroll et al. (2009) state that the United States Geological Survey (USGS) Death Valley Regional Flow System (DVRFS) model, which is based on MODFLOW, is “conceptually inaccurate in that it models an unconfined aquifer as a confined system and does not simulate unconfined drawdown in transient pumping simulations.” Carroll et al. (2009) claim that “more realistic estimates of water availability” can be produced by a SURFACT-based model of the DVRFS that simulates unconfined groundwater flow and limits withdrawals from wells to avoid excessive drawdown. Differences in results from the original MODFLOW-based model and the SURFACT-based model stem primarily from application by Carroll et al. (2009) of head limits that can also be applied using the existing MODLOW model and not from any substantial difference in the accuracy with which the unconfined aquifer is represented in the two models. In a hypothetical 50-year predictive simulation presented by Carroll et al. (2009), large differences between the models are shown when simulating pumping from the lower clastic confining unit, where the transmissivity is nearly two orders of magnitude less than in an alluvial aquifer. Yet even for this extreme example, drawdowns and pumping rates from the MODFLOW and SURFACT models are similar when the head-limit capabilities of the MODFLOW MNW Package are applied. These similarities persist despite possible discrepancies between assigned hydraulic properties. The resulting comparison between the MODFLOW and SURFACT models of the DVRFS suggests that approximating the unconfined system in the DVRFS as a constant-saturated-thickness system (called a “confined system” by Carroll et al., 2009) performs very well.

Reaching High Bookshelves From a Wheelchair

NASA Technical Reports Server (NTRS)

Walch, A. J.

1982-01-01

"Book retriever" allows people confined to wheelchairs to remove or replace books from upper shelves of library stacks. Retriever is mechanical device composed of aluminum tube approximately 5 feet long with two jaws at upper end. Jaws securely clamp selected book; they are thin enough to be inserted between adjacent books.

Hydrogeology, Chemical Characteristics, and Transport Processes in the Zone of Contribution of a Public-Supply Well in York, Nebraska

USGS Publications Warehouse

Landon, Matthew K.; Clark, Brian R.; McMahon, Peter B.; McGuire, Virginia L.; Turco, Michael J.

2008-01-01

In 2001, the U.S. Geological Survey, as part of the National Water Quality Assessment (NAWQA) Program, initiated a topical study of Transport of Anthropogenic and Natural Contaminants (TANC) to PSW (public-supply wells). Local-scale and regional-scale TANC study areas were delineated within selected NAWQA study units for intensive study of processes effecting transport of contaminants to PSWs. This report describes results from a local-scale TANC study area at York, Nebraska, within the High Plains aquifer, including the hydrogeology and geochemistry of a 108-square-kilometer study area that contains the zone of contribution to a PSW selected for study (study PSW), and describes factors controlling the transport of selected anthropogenic and natural contaminants to PSWs. Within the local-scale TANC study area, the High Plains aquifer is approximately 75 m (meter) thick, and includes an unconfined aquifer, an upper confining unit, an upper confined aquifer, and a lower confining unit with lower confined sand lenses (units below the upper confining unit are referred to as confined aquifers) in unconsolidated alluvial and glacial deposits overlain by loess and underlain by Cretaceous shale. From northwest to southeast, land use in the local-scale TANC study area changes from predominantly irrigated agricultural land to residential and commercial land in the small community of York (population approximately 8,100). For the purposes of comparing water chemistry, wells were classified by degree of aquifer confinement (unconfined and confined), depth in the unconfined aquifer (shallow and deep), land use (urban and agricultural), and extent of mixing in wells in the confined aquifer with water from the unconfined aquifer (mixed and unmixed). Oxygen (delta 18O) and hydrogen (delta D) stable isotopic values indicated a clear isotopic contrast between shallow wells in the unconfined aquifer (hereinafter, unconfined shallow wells) and most monitoring wells in the confined aquifers (hereinafter, confined unmixed wells). Delta 18O and delta D values for a minority of wells in the confined aquifers were intermediate between those for the unconfined shallow wells and those for the confined unmixed wells. These intermediate values were consistent with mixing of water from unconfined and confined aquifers (hereinafter, confined mixed wells). Oxidation-reduction conditions were primarily oxic in the unconfined aquifer and variably reducing in the confined aquifers. Trace amounts of volatile organic compounds (VOC), particularly tetrachloroethylene (PCE) and trichloroethylene (TCE), were widely detected in unconfined shallow urban wells and indicated the presence of young urban recharge waters in most confined mixed wells. The presence of degradation products of agricultural pesticides (acetochlor and alachlor) in some confined mixed wells suggests that some fraction of the water in these wells also was the result of recharge in agricultural areas. In the unconfined aquifer, age-tracer data (chlorofluorocarbon and sulfur hexafluoride data, and tritium to helium-3 ratios) fit a piston-flow model, with apparent recharge ages ranging from 7 to 48 years and generally increasing with depth. Age-tracer data for the confined aquifers were consistent with mixing of 'old' water, not containing modern tracers recharged in the last 60 years, and exponentially-mixed 'young' water with modern tracers. Confined unmixed wells contained less than (=) 97% of old water. Confined mixed wells contained >30% young water and mean ages ranged from 12 to 14 years. Median concentrations of nitrate (as nitrogen, hereinafter, nitrate-N) were 17.3 and 16.0 mg/L (milligram per liter) in unconfined shallow urban and agricultural wells, respectively, indicating a range of likely nitrate sources. Septic systems are most numerous near the edge of the urban area and appear to be

Facies analysis of Late Proterozoic through Lower Cambrian rocks of the Death Valley regional ground-water system and surrounding areas, Nevada and California

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

Sweetkind, D.S.; White, D.K.

Late Proterozoic through Lower Cambrian rocks in the southern Great Basin form a westward-thickening wedge of predominantly clastic deposits that record deposition on the early western shelf edge of western North America (Stewart and Poole, 1974; Poole and others, 1992). Regional analyses of geologic controls on ground-water flow in the southern Great Basin typically combined lithostratigraphic units into more general hydrogeologic units that have considerable lateral extent and distinct hydrologic properties. The Late Proterozoic through Lower Cambrian rocks have been treated as a single hydrogeologic unit, named the lower clastic aquitard (Winograd and Thordarson, 1975) or the quartzite confining unitmore » (Laczniak and others, 1996), that serves as the hydrologic basement to the flow system. Although accurate in a general sense, this classification ignores well-established facies relations within these rocks that might increase bedrock permeability and locally influence ground-water flow . This report presents a facies analysis of Late Proterozoic through Lower Cambrian rocks (hereafter called the study interval) in the Death Valley regional ground-water flow system - that portion of the southern Great Basin that includes Death Valley, the Nevada Test Site, and the potential high-level nuclear waste underground repository at Yucca Mountain (fig. 1). The region discussed in this report, hereafter called the study area, covers approximately 100,000 km2 (lat 35 degrees-38 degrees 15'N., long 115 degrees-118 degrees W.). The purpose of this analysis is to provide a general documentation of facies transitions within the Late Proterozoic through Lower Cambrian rocks in order to provide an estimate of material properties (via rock type, grain size, and bedding characteristics) for specific hydrogeologic units to be included in a regional ground-water flow model.« less

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

Lefeuvre, F.E.; Wrolstad, K.H.; Zou, Ke Shan

Total and Unocal estimated sand-shale ratios in gas reservoirs from the upper Tertiary clastics of Myanmar. They separately used deterministic pre-stack and statistical post-stack seismic attribute analysis calibrated at two wells to objectively extrapolate the lithologies and reservoir properties several kilometers away from the wells. The two approaches were then integrated and lead to a unique distribution of the sands and shales in the reservoir which fit in the known regional geological model. For the sands, the fluid distributions (gas and brine) were also estimated as well as the porosity, water saturation, thickness and clay content of the sands. Thismore » was made possible by using precise elastic modeling based on the Biot-Gassmann equation in order to integrate the effects of reservoir properties on seismic signatures.« less

Rock Magnetic Properties of Remagnetised Devonian and Carboniferous Carbonate and Clastic Rocks From The NE Rhenish Massif, Germany

NASA Astrophysics Data System (ADS)

Zwing, A.; Matzka, J.; Bachtadse, V.; Soffel, H. C.

Previous studies on remagnetised carbonate rocks from the North American and Eu- ropean Variscides reported characteristic rock magnetic properties which are thought to be diagnostic for a chemical remagnetisation event. Their hysteresis properties with high ratios of Mrs/Ms and Hcr/Hc indicate the presence of a mixture of single-domain and superparamagnetic magnetite (Jackson, et al. 1990). In order to test if this fin- gerprint can be identified in remagnetised carbonate and clastic rocks from the NE Rhenish Massif, Germany, a series of rock magnetic experiments has been carried out. The hysteresis properties of the remagnetised clastic rocks indicate the domi- nance of large MD particles, as can be expected for detrital sediments. The carbon- ates yield significantly higher ratios of Mrs/Ms and Hcr/Hc than the clastic rocks, but only partly correspond to the characteristic properties of remagnetised carbon- ates described above. The latter might be attributed to detrital input into the carbonate platforms. Additional low-temperature remanence measurements show a wide vari- ety of phenomena, including Verwey transitions and indications for the presence of superparamagnetic grains. However, the low-temperature experiments do not allow a straightforward discrimination between the clastic and carbonate rocks and suggest more complex magnetomineralogies than expected from the hysteresis measurements alone.

Effect of nanostructured surface configuration on evaporation and condensation characteristics of thin film liquid argon in a nano-scale confinement

NASA Astrophysics Data System (ADS)

Kuri, Subrata Kumar; Rakibuzzaman, S. M.; Sabah, Arefiny; Ahmed, Jannat; Hasan, Mohammad Nasim

2017-12-01

Molecular dynamics simulation has been carried out to go through the evaporation and condensation characteristics of thin liquid argon film in nanoscale confinement having nanostructured boundary. Nanoscale confinement under consideration consists of hot and cold parallel platinum plates at the bottom and top end of a model cuboid inside which the fluid domain comprised of liquid argon film at the bottom plate and vapor argon in between liquid argon and upper plate of the confinement. Three different confinement configurations have been considered here: (i) Both platinum plates are flat, (ii) Upper plate consisting of transverse slots and (iii) Both plates consisting of transverse slots. The height of the slots is 1.5 nm. Considering hydrophilic nature of top and bottom plates, two different high temperatures of the hot wall was set and an observation was made. For all the structures, equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. Then the lower wall is set to two different temperatures like 110 K and 250 K for all three models to perform non-equilibrium molecular dynamics (NEMD). Various system characteristics such as atomic distribution, wall heat flux, evaporative mass flux etc. have been obtained and discussed to have a clear understanding of the effect of nanotextured surface on phase change phenomena.

Intra-continental subduction and contemporaneous lateral extrusion of the upper plate: insights into Alps-Adria interactions

NASA Astrophysics Data System (ADS)

van Gelder, Inge; Willingshofer, Ernst; Sokoutis, Dimitrios; Cloetingh, Sierd

2017-04-01

A series of physical analogue experiments were performed to simulate intra-continental subduction contemporaneous with lateral extrusion of the upper plate to study the interferences between these two processes at crustal levels and in the lithospheric mantle. The lithospheric-scale models are specifically designed to represent the collision of the Adriatic microplate with the Eastern Alps, simulated by an intra-continental weak zone to initiate subduction and a weak confined margin perpendicular to the direction of convergence in order to allow for extrusion of the lithosphere. The weak confined margin is the analog for the opening of the Pannonian back-arc basin adjacent to the Eastern Alps with the direction of extension perpendicular to the strike of the orogen. The models show that intra-continental subduction and coeval lateral extrusion of the upper plate are compatible processes. The obtained deformation structures within the extruding region are similar compared to the classical setup where lateral extrusion is provoked by lithosphere-scale indentation. In the models a strong coupling across the subduction boundary allows for the transfer of abundant stresses to the upper plate, leading to laterally varying strain regimes that are characterized by crustal thickening near a confined margin and dominated by lateral displacement of material near a weak lateral confinement. During ongoing convergence the strain regimes propagate laterally, thereby creating an area of overlap characterized by transpression. In models with oblique subduction, with respect to the convergence direction, less deformation of the upper plate is observed and as a consequence the amount of lateral extrusion decreases. Additionally, strain is partitioned along the oblique plate boundary leading to less subduction in expense of right lateral displacement close to the weak lateral confinement. Both oblique and orthogonal subduction models have a strong resemblance to lateral extrusion tectonics of the Eastern Alps, where subduction of the adjacent Adriatic plate beneath the Eastern Alps is debated. Our results highlight that both indentation and subduction of Adria are valid collisional mechanisms to provoke lateral extrusion-type deformation within the Eastern Alps lithosphere, i.e. the upper plate. Moreover, the insights suggest that the Oligocene to Late Miocene structural evolution of the Eastern Alps is best described by phases of oblique and subsequent orthogonal subduction which is in line with Miocene rotations of the Adriatic plate. Furthermore, oblique subduction of the Adriatic plate provides a viable mechanism to explain the rapid decrease in slab length beneath the Eastern Alps towards the Pannonian Basin, also implying that the Adriatic slab can behave and form independently with regards to the adjacent subduction of Adria beneath the Dinarides.

Cost and Performance Report of Electrical Resistance Heating (ERH) for Source Treatment. Addendum

DTIC Science & Technology

2008-09-29

and clay. The Upper Cretaceous Severn, Matawan, and Magothy Formations underlie the Brightseat Formation. The groundwater table at the site is...Table 1, the aquifers include, in descending order, the Aquia, the Monmouth, the Magothy , the Upper and Lower Patapsco and the Patuxent. The... Magothy Magothy Aquifer Sand, light-gray to white, with interbedded thin layers of organic clay. _-300(1) Confining Unit _-360(1) Upper Patapsco

Modelling fluid flow in clastic eruptions: application to the Lusi mud eruption.

NASA Astrophysics Data System (ADS)

Collignon, Marine; Schmid, Daniel W.; Galerne, Christophe; Lupi, Matteo; Mazzini, Adriano

2017-04-01

Clastic eruptions involve the rapid ascension of clasts together with fluids, gas and/or liquid phases that may deform and brecciate the host rocks. These fluids transport the resulting mixture, called mud breccia, to the surface. Such eruptions are often associated with geological structures such as mud volcanoes, hydrothermal vent complexes and more generally piercement structures. They involve various processes, acting over a wide range of scales which makes them a complex and challenging, multi-phase system to model. Although piercement structures have been widely studied and discussed, only few attempts have been made to model the dynamics of such clastic eruptions. The ongoing Lusi mud eruption, in the East Java back-arc basin, which began in May 2006, is probably the most spectacular clastic eruption. Lusi's eruptive behaviour has been extensively studied over the past decade and thus represents a unique opportunity to better understand the dynamics driving clastic eruptions, including fossil clastic systems. We use both analytical formulations and numerical models to simulate Lusi's eruptive dynamics and to investigate simple relationships between the mud breccia properties (density, viscosity, gas and clast content) and the volumetric flow rate. Our results show that the conduit radius of such piercement system cannot exceeds a few meters at depth, and that clasts, if not densely packed, will not affect the flow rate when they are smaller than a fifth of the conduit size. Using published data for the annual gas fluxes at Lusi, we infer a maximal depth at which exsolution starts. This occurs between 1800 m and 3200 m deep for the methane and between 750 m and 1000 m for the carbon dioxide.

Some Cenozoic hydrocarbon basins on the continental shelf of Vietnam

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

Dien, P.T.

1994-07-01

The formation of the East Vietnam Sea basins was related to different geodynamic processes. The pre-Oligocene basement consists of igneous, metamorphic, and metasediment complexes. The Cretaceous-Eocene basement formations are formed by convergence of continents after destruction of the Tethys Ocean. Many Jurassic-Eocene fractured magmatic highs of the Cuulong basin basement constitute important reservoirs that are producing good crude oil. The Paleocene-Eocene formations are characterized by intramountain metamolasses, sometimes interbedded volcanic rocks. Interior structures of the Tertiary basins connect with rifted branches of the widened East Vietnam Sea. Bacbo (Song Hong) basin is predominated by alluvial-rhythmic clastics in high-constructive deltas, whichmore » developed on the rifting and sagging structures of the continental branch. Petroleum plays are constituted from Type III source rocks, clastic reservoirs, and local caprocks. Cuulong basin represents sagging structures and is predominated by fine clastics, with tidal-lagoonal fine sandstone and shalestone in high-destructive deltas that are rich in Type II source rocks. The association of the pre-Cenozoic fractured basement reservoirs and the Oligocene-Miocene clastic reservoir sequences with the Oligocene source rocks and the good caprocks is frequently met in petroleum plays of this basin. Nan Conson basin was formed from complicated structures that are related to spreading of the oceanic branch. This basin is characterized by Oligocene epicontinental fine clastics and Miocene marine carbonates that are rich in Types I, II, and III organic matter. There are both pre-Cenozoic fractured basement reservoirs, Miocene buildup carbonate reservoir rocks and Oligocene-Miocene clastic reservoir sequences, in this basin. Pliocene-Quaternary sediments are sand and mud carbonates in the shelf facies of the East Vietnam Sea back-arc basin. Their great thickness provides good conditions for maturation and trapping.« less

Hydrogeology and water quality of the shallow aquifer system at the Mainside, Naval Surface Warfare Center, Dahlgren Site, Dahlgren, Virginia

USGS Publications Warehouse

Harlow, G.E.; Bell, C.F.

1996-01-01

Lithologic and geophysical logs of boreholes at 29 sites show that the hydrogeologic framework of the Mainside of the Naval Surface Warfare Center, Dahlgren Site at Dahlgren, Virginia, consists of un-consolidated sedimentary deposits of gravel, sand, silt, and clay. The upper 220 feet of these sediments are divided into five hydrogeologic units, including the (1) Columbia (water-table) aquifer, (2) upper confining unit, (3) upper confined aquifer, (4) Nanjemoy-Marlboro confining unit, and (5) Aquia aquifer. The Columbia aquifer in the study area is a local system that is not affected by regional pumping. Ground-water recharge occurs at topographic highs in the northern part of the Mainside, and ground-water discharge occurs at topographic lows associated with adjacent surface-water bodies. Regionally, the direction of ground-water flow in the upper confined and Aquia aquifers is toward the southwest and southeast, respectively. A downward hydraulic gradient exists between the aquifers in the shallow system, and stresses on the Aquia aquifer are indicated by heads that range between 2 and 12 feet below sea level. The ratio of median horizontal hydraulic conductivity of the Columbia aquifer to median vertical hydraulic con-ductivity of the upper confining unit, however, is approximately 2,600:1; therefore, under natural- flow conditions, most water in the Columbia aquifer probably discharges to adjacent surface- water bodies. The composition and distribution of major ions vary in the Columbia aquifer. In general, water samples from wells located along the inland perimeter roads of the study area have chloride or a combination of chloride and sulfate as the dominant anions, and water samples from wells located in the interior of the study area have bicarbonate or a combination of bicarbonate and sulfate as the dominant anions. Sodium and calcium were the dominant cations in most samples. Dissolved solids and four inorganic constituents are present in water from the Columbia aquifer at concentrations that exceed the secondary maximum contaminant levels (SMCL's) for drinking water established by the U.S. Environmental Protection Agency. Concentration of dissolved solids exceed the SMCL of 500 milligrams per liter in 3 of 29 samples from the Columbia aquifer. An elevated concentration of sodium is present in one water sample, and elevated concentrations of chloride are present in two water samples. Concentrations of dissolved iron and manga-nese exceed the SMCL in 10 and 17 of 29 water samples, respectively, and are the most extensive water-quality problem with regard to inorganic constituents in the Columbia aquifer.

Criteria for successful exploration for Miocene reef production in the Philippines

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

Downey, M.W.

1990-06-01

An abundance of modern geologic, geophysical, and geochemical data has been provided to interested members of the petroleum industry by the Philippine government, in cooperation with the World Bank. These data have been analyzed to assess whether more, and larger, Miocene reef fields should be expected in the Philippines. In the past decade, exploration by Cities Service (OXY), Amoco, Alcorn, and others has resulted in the discovery of several small Miocene reef and Miocene sandstone oil fields in offshore Palawan. Phillips/Shell also made a significant gas discovery of about 750 bcf in a Palawan Miocene reef that is currently uneconomicmore » to develop given the water depth (1,090 ft) and distance from users. Miocene reefs are commonly buried within Miocene clastics, and, where these impinging clastics are porous, they allow pathways for hydrocarbons to leak from the Miocene reefs. Drape closure is an important positive factor in assessing seal risk for Philippine Miocene reefs. Source rocks to charge middle and upper Miocene reefs are typically restricted to lower Miocene horizons. Geothermal gradients are modest in much of the Philippine offshore, and only select areas provide sufficient burial to mature and expel significant hydrocarbons. It is predicted by the author that additional, larger, and highly profitable Miocene reef fields will be found by future explorers in areas where Miocene reefs have drape closure top seals and are adjacent to deeply buried Miocene source rocks.« less

Hydrogeologic Framework of Onslow County, North Carolina, 2008

USGS Publications Warehouse

Fine, Jason M.

2008-01-01

The unconsolidated sediments that underlie the Onslow County area are composed of interlayered permeable and impermeable beds, which overlie the crystalline basement rocks. The aquifers, composed mostly of sand and limestone, are separated by confining units composed mostly of clay and silt. The aquifers from top to bottom are the surficial, Castle Hayne, Beaufort, Peedee, Black Creek, and Upper and Lower Cape Fear aquifers. For this study, the Castle Hayne aquifer is informally divided into the upper and lower Castle Hayne aquifers. The eight aquifers and seven confining units of the Tertiary and Cretaceous strata beneath Onslow County are presented in seven hydrogeologic sections. The hydrogeologic framework was refined from existing interpretations by using geophysical logs, driller's logs, and other available data from 123 wells and boreholes.

Geologic characterization report for the Paradox Basin Study Region, Utah Study Areas. Volume 6: Salt Valley

NASA Astrophysics Data System (ADS)

1984-12-01

Surface landforms in the Salt Valley Area are generally a function of the Salt Valley anticline and are characterized by parallel and subparallel cuestaform ridges and hogbacks and flat valley floors. The most prominent structure in the Area is the Salt Valley anticline. Erosion resulting from the Tertiary uplift of the Colorado Plateau led to salt dissolution and subsequent collapse along the crest of the anticline. Continued erosion removed the collapse material, forming an axial valley along the crest of the anticline. Paleozoic rocks beneath the salt bearing Paradox Formation consist of limestone, dolomite, sandstone, siltstone and shale. The salt beds of the Paradox formation occur in distinct cycles separated by an interbed sequence of anhydrite, carbonate, and clastic rocks. The Paradox Formation is overlain by Pennsylvanian limestone; Permian sandstone; and Mesozoic sandstone, mudstone, conglomerate and shale. No earthquakes have been reported in the area during the period of the historic record and contemporary seismicity appears to be diffusely distributed, of low level and small magnitude. The upper unit includes the Permian strata and upper Honaker trail formation.

Nonlocal response in plasmonic waveguiding with extreme light confinement

NASA Astrophysics Data System (ADS)

Toscano, Giuseppe; Raza, Søren; Yan, Wei; Jeppesen, Claus; Xiao, Sanshui; Wubs, Martijn; Jauho, Antti-Pekka; Bozhevolnyi, Sergey I.; Mortensen, N. Asger

2013-07-01

We present a novel wave equation for linearized plasmonic response, obtained by combining the coupled real-space differential equations for the electric field and current density. Nonlocal dynamics are fully accounted for, and the formulation is very well suited for numerical implementation, allowing us to study waveguides with subnanometer cross-sections exhibiting extreme light confinement. We show that groove and wedge waveguides have a fundamental lower limit in their mode confinement, only captured by the nonlocal theory. The limitation translates into an upper limit for the corresponding Purcell factors, and thus has important implications for quantum plasmonics.

Inter-aquifer Dynamics in and Near a Confining Unit Window in Shelby County, Tennessee, USA

NASA Astrophysics Data System (ADS)

Gentry, R. W.; McKay, L. D.; Larsen, D.; Carmichael, J. K.; Solomon, D. K.; Thonnard, N.; Anderson, J. L.

2003-12-01

An interdisplinary research team is investigating the interaction between the surficial alluvial aquifer and the deeper confined Memphis aquifer in the Memphis area, Shelby County, Tennessee. Previous research has identified a window in the clay-rich, upper Claiborne confining unit that separates the two aquifers near a closed municipal landfill in east-central Shelby County, an area undergoing rapid urbanization. For this investigation, a combination of environmental tracers (tritium/helium-3), major and trace ion geochemistry, hydraulic response testing, measurement of hydraulic gradients, and groundwater flow modeling is being used to quantify recharge of young water from the alluvial aquifer through the window to the Memphis aquifer. The research will provide results to better understand how windows were formed and how they influence recharge and water quality in otherwise confined parts of the Memphis aquifer downdip of its outcrop/subcrop area. Examination of continuous core samples and geophysical logs from wells installed for the study using Rotasonic drilling methods confirmed the existence of a sand-dominated window that may be as much as 1 km in diameter in the upper Claiborne confining unit. The upper Claiborne confining unit is 15 to 20 m thick in most of the study area and is overlain by a 10 to 12 m thick alluvial aquifer. The window is interpreted to have formed as a result of depositional and incisional processes in an Eocene-age deltaic system. Hydraulic gradients of several feet exist vertically between the alluvial and Memphis aquifers within the window, indicating downward flow. Groundwater age-dates from tritium/helium-3 analyses indicate that groundwater in the window at the depth of the base of the surrounding confining unit (approximately 30 m) has an apparent age of 19.8 years, which confirms the occurrence of downward flow. Young groundwater age dates (less than 32 years) also were obtained from wells in the Memphis aquifer at confined sites downgradient of the window, suggesting that a plume of young water is spreading outwards from the window and mixing with the older Memphis aquifer water. Preliminary inverse modeling of the site using a genetic algorithm coupled with a central finite difference flow model indicates a probable steady-state downward flux of about 12,000 m3/d through the window. Collection and analysis of additional groundwater samples are planned to examine geochemical conditions in the confining unit and in the Memphis aquifer upgradient of the window. These analyses will aid in developing a final conceptual model and in subsequent numerical modeling of mixing of the young recharge water with the older Memphis aquifer water.

Anatomically preserved marattiales from coal swamps of the Desmoinesian and Missourian of the midcontinent United States: Systematics, ecology and evolution

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

Lesnikowska, A.D.

1989-01-01

Eleven species-level assemblages of stems, frond members and fertile foliage of anatomically preserved Marattiales are proposed, based on specimens in coal balls from 16 coals in the Desmoinesian and Missourian (Westphalian D and Stephanian) of the Illinois, Forest City and Arkoma Basins. Four new combinations, Psaronius calicifolius (Millay) Lesnikowska, and Psaronius gnomus (Lesnikowska Millay) Lesnikowska, Psaronius illinoensis (Eqart) Lesnikowska, and Psaronius minor (Hoskins) Lesnikowska are made to accommodate well documented assemblages and seven are treated informally. The taxonomy of the fertile foliage is revised as follows: Scolecopteris dispora Lesnikowska sp. nov. is described from an Iowa coal and Scolecopteris parkerensismore » Lesnikowska sp. nov. from the Parker Coal of Indiana. Scolecopteris fragilis is made a synonym of S. mamayi, and S. revoluta, and S. saharaensis synonyms of S. minor. The type and Middle Pennsylvanian specimens of Scolecopteris parvifolia belong in S. minor but the Upper Pennsylvanian specimens are S. illinoensis. Only one species occurs in both the Middle and the Upper Pennsylvanian; the extinction event near the Middle/Upper Pennsylvanian boundary extended to coal-swamp Marattiales as well as tree lycopods. The Upper Pennsylvanian tree ferns are interpreted as derived from clastic-swamp species that recolonized the coal-swamp habitat after this extinction. Upper Pennsylvanian tree ferns were significantly larger than Middle Pennsylvanian ones and were characterized by a massive root mantle whereas as least one Middle Pennsylvanian species lacked a root mantle and had a scrambling habit. Biomass allocation to reproduction was significantly greater in the Middle Pennsylvanian species.« less

Lithostratigraphical correlation of the Neoproterozoic Roan Supergroup from Shaba (Zaire) and Zambia, in the central African copper-cobalt metallogenic province

NASA Astrophysics Data System (ADS)

Cailteux, J.; Binda, P. L.; Katekesha, W. M.; Kampunzu, A. B.; Intiomale, M. M.; Kapenda, D.; Kaunda, C.; Ngongo, K.; Tshiauka, T.; Wendorff, M.

1994-11-01

New data on the lower Katangan sequences in Shaba (Zaire) and Zambia, collected during the 1989 and 1990 UNESCO-sponsored Geotraverses, reveal an important development on friction breccias throughout the Zambian Copperbelt, which still remains poorly documented, and shows that the Zairean and Zambian facies of the Roan Supergroup can be correlated in detail. As in Zaire, the deformation of Katangan terranes during the Lufilian orogeny produced important friction breccias in Zambia. Such breccias occur mostly between the upper part of the Lower Roan Supergroup and the Mwashya Group (R-4): above the shale with grit (RL3) at Konkola and Mindola, or within the Upper Roan Dolomite at Chambishi South, Muliashi and Nchanga. At Mufulira, a typical fragment of Shaba Mines Group was observed within a major heterogeneous tectonic breccia. This situation is similar to that reported at Kipapila (Kimpe) and Lubembe in Zaire, both located on the same tectonic trend as Mufulira. However, a continuous stratigraphical succession can be observed in Zambia from the basal unconformity to the Mwashya Group. Strong lithological similarities were found, formation by formation, between the Roan sequences of Zambia and Zaire. In particular, the complete Mines Group of Zaire (R-2) and the units from the RL6 to the RL4 in Zambia were deposited under comparable conditions of sedimentation and show a similar and correlatable evolution of lithologies. Furthermore, the overlying Dipeta Group (R-3) of Zaire and the RL3, RU2/RU1 of Zambia, are equally comparable. Above the Upper Roan Dolomite, Lower Mwashya dolomitic rocks, identical with the ones of Shaba, have been noted to occur in Zambia in stratigraphical continuity with the typical black shales of the Upper Mwashya. The correlation between the coarse clastics of the Zambian footwall (RL7) and the red dolomitic argillites and sandstones of the Zairean R.A.T. (Roches Argillo Talqueuses: R-1) remains uncertain. However these two sequences show some similarities suggesting a lateral facies change from high-energy siliciclastic sedimentation in Zambia, to quieter, less clastic and more carbonate rich sedimentation in Zaire. In agreement with the proposed lithostratigraphical correlation, volcanic and pyroclastic rocks, occurring both in Zaire and Zambia in the Lower Mwashya, testify to a major period of igneous activity in the region. Intrusive rocks found in the Zambian Roan Group and in the Zairean Dipeta Group can probably be attributed to the same episode of magmatism. Finally it can be shown that several copper-cobalt orebodies are found at the same lithostratigraphical position in Zambia and Zaire: the Zambian ore shale corresponds to the classical Shaba orebodies at the base of the Mines Group (R-2), the Nchanga upper orebody to the lower R-2.3 mineralization and the Zambian RL3 anomalous copper occurrences to those of the R-3.1.2 Dipeta unit.

Hydrogeology and groundwater quality of Highlands County, Florida

USGS Publications Warehouse

Spechler, Rick M.

2010-01-01

Groundwater is the main source of water supply in Highlands County, Florida. As the demand for water in the county increases, additional information about local groundwater resources is needed to manage and develop the water supply effectively. To address the need for additional data, a study was conducted to evaluate the hydrogeology and groundwater quality of Highlands County. Total groundwater use in Highlands County has increased steadily since 1965. Total groundwater withdrawals increased from about 37 million gallons per day in 1965 to about 107 million gallons per day in 2005. Much of this increase in water use is related to agricultural activities, especially citrus cultivation, which increased more than 300 percent from 1965 to 2005. Highlands County is underlain by three principal hydrogeologic units. The uppermost water-bearing unit is the surficial aquifer, which is underlain by the intermediate aquifer system/intermediate confining unit. The lowermost hydrogeologic unit is the Floridan aquifer system, which consists of the Upper Floridan aquifer, as many as three middle confining units, and the Lower Floridan aquifer. The surficial aquifer consists primarily of fine-to-medium grained quartz sand with varying amounts of clay and silt. The aquifer system is unconfined and underlies the entire county. The thickness of the surficial aquifer is highly variable, ranging from less than 50 to more than 300 feet. Groundwater in the surficial aquifer is recharged primarily by precipitation, but also by septic tanks, irrigation from wells, seepage from lakes and streams, and the lateral groundwater inflow from adjacent areas. The intermediate aquifer system/intermediate confining unit acts as a confining layer (except where breached by sinkholes) that restricts the vertical movement of water between the surficial aquifer and the underlying Upper Floridan aquifer. The sediments have varying degrees of permeability and consist of permeable limestone, dolostone, or sand, or relatively impermeable layers of clay, clayey sand, or clayey carbonates. The thickness of the intermediate aquifer system/ intermediate confining unit ranges from about 200 feet in northwestern Highlands County to more than 600 feet in the southwestern part. Although the intermediate aquifer system is present in the county, it is unclear where the aquifer system grades into a confining unit in the eastern part of the county. Up to two water-bearing units are present in the intermediate aquifer system within the county. The lateral continuity and water-bearing potential of the various aquifers within the intermediate aquifer system are highly variable. The Floridan aquifer system is composed of a thick sequence of limestone and dolostone of Upper Paleocene to Oligocene age. The top of the aquifer system ranges from less than 200 feet below NGVD 29 in extreme northwestern Highlands County to more than 600 feet below NGVD 29 in the southwestern part. The principal source of groundwater supply in the county is the Upper Floridan aquifer. As of 2005, about 89 percent of the groundwater withdrawn from the county was obtained from this aquifer, mostly for agricultural irrigation and public supply. Over most of Highlands County, the Upper Floridan aquifer generally contains freshwater, and the Lower Floridan aquifer contains more mineralized water. The potentiometric surface of the Upper Floridan aquifer is constantly fluctuating, mainly in response to seasonal variations in rainfall and groundwater withdrawals. The potentiometric surface of the Upper Floridan aquifer in May 2007, which represents the hydrologic conditions near the end of the dry season when water levels generally are near their lowest, ranged from about 79 feet above NGVD 29 in northwestern Highlands County to about 40 feet above NGVD 29 in the southeastern part of the county. The potentiometric surface of the Upper Floridan aquifer in September 2007 was about 3 to 10 feet high

Evolution of the Alpine Tethys (Sava) suture zone in Fruška Gora Mountains (N Serbia): from orogenic building to tectonic omissions

NASA Astrophysics Data System (ADS)

Toljić, Marinko; Matenco, Liviu; ĐErić, Nevenka; Milivojević, Jelena; Gerzina, Nataša.; Stojadinović, Uros

2010-05-01

The Fru\\vska Gora Mountains in northern Serbia offers an unique opportunity to study the Cretaceous-Eocene evolution of the NE part of the Dinarides, which is largely covered elsewhere beneath the thick Miocene sediments of the Pannonian basin, deposited during the back-arc collapse associated with the subduction and roll-back recorded in the external Carpathians. The structural grain of the Fru\\vska Gora Mountains is the one of a large scale antiform, exposing a complex puzzle of highly deformed metamorphic rocks in its centre and Triassic-Miocene sequence of non-metamorphosed sediments, ophiolites and volcanics along its flanks. The metamorphic rocks were the target of structural investigations coupled with paleontological dating (conodonts, palynomorphs and radiolarians) in an effort to unravel the geodynamic evolution of an area thought to be located near the suture zone between the Tisza upper plate and the Adriatic lower plate, i.e. the Sava subduction zone of the Dinarides (e.g., Pamic, 2002; Schmid et al., 2008). The existence of this subduction zone was previously inferred here by local observations, such as metamorphosed Mesozoic sediments containing Middle Triassic conodonts (Đurđanović, 1971) or Early Cretaceous blue schists metamorphism (123±5 Ma, Milovanović et al., 1995). The metamorphic sequence is characterized by a Paleozoic age meta-sedimentary basement which contains palynomorphs of Upper Paleozoic - Carboniferous age and a meta-sedimentary and meta-volcanic sequence which contain a succession of contrasting metamorphosed lithologies such sandstones, black limestones, shallow water white limestones, basic volcanic sequences, deep nodular limestiones, radiolarites, meta-ophiolites and turbiditic sequences. The lower part of the sequence is contrastingly similar with the Triassic cover of the Drina-Ivanijca thrust sheet and its metamorphosed equivalent observed in the Kopaonik and Studenica series (Schefer et al., in press). This observation is supported by the newly found micro-fauna of Upper Triassic in age in the meta-sandstones associated with meta-volcanics on the SW slopes of the mountain. The upper part of the sequence display metamorphosed "flysh"-type of sequences and meta-basalts. In these deposits, slightly metamorphosed siliciclastics (lithic sandstones with volcanic-derived clasts) previously interpreted as Upper Jurassic mélange have proved to contain Upper Cretaceous palynomorphs. Among the rocks exposed in the metamorphic core of the mountains, the SW slope of Fru\\vska Gora offers the optimal locality for the study of the kinematic evolution. Here, four phases of folding have been mapped, being associated mainly with large-scale regional contraction. The first phase is characterized by isoclinal folding, with reconstructed SW vergence. The second generation of E-W oriented and coaxial folds is asymmetric and is up to metres in size, displaying a south vergence and has largely refolded the previous generation. The third event was responsible for the formation of upright folds, yet again E-W oriented, re-folding earlier structures. The first two phases of folding are associated with metamorphic conditions, while the third was apparently near the transition with the brittle domain. The relationship with a fourth folding event observed also in the non-metamorphosed clastic-carbonate rocks is rather uncertain, but is apparently associated with the present day antiformal structure of the Fuska Gora Mountains. Interestingly, the metamorphosed Triassic and Upper Cretaceous carbonatic-clastic sequence in the core of the antiform is in structural contact along the antiformal flanks with Lower-Middle Triassic and Upper Cretaceous-Paleogene sediments which display the same facies, but these are not metamorphosed. This demonstrates a large scale tectonic omission along the flanks of the Fru\\vska Gora antiform, 9-10km of rocks being removed by what we speculatively define as an extensional detachment exhuming the metamorphic core. This detachment has been subsequently folded into the present-day antiformal geometry of the Fru\\vska Gora Mountains. These findings demonstrate that the metamorphic and non-metamorphic Upper Cretaceous - Paleogene clastic-carbonate sediments belongs to the main Alpine Tethys (Sava) subduction zone of the Dinarides. The Paleozoic-Triassic metamorphic and non-metamorphic rocks belong to the distal Adriatic lower plate, or more precisely to the Jadar-Kopaonik composite thrust sheet (Schmid et al., 2008), while the layer of serpentinized peridotite found at their contact most probably belongs to the Western Vardar ophiolites obducted over the Adriatic plate during Late Jurassic - Earliest Cretaceous. The distal Jadar-Kopaonik composite unit was partly affected by strong contractional deformation and a Late Eocene greenschist facies metamorphism during the main phase of subduction and collision, similarly to what has been observed elsewhere in the Dinarides (Pamić, 2002; Schefer et al., in press). A Miocene phase of core-complex formation was responsible for the large tectonic omission observed, being probably followed by the formation of a wide open antiformal structure during the Pliocene-Quaternary inversion of the Pannonian basin.

Influence of the confining pressure on precursory and rupture processes of Westerly granite.

NASA Astrophysics Data System (ADS)

Passelegue, Francois; Nicolas, Aurelien; Madonna, Claudio; Schubnel, Alexandre

2016-04-01

In the shallow crust, brittle deformation mechanisms lead to damage and rupture of rocks. These mechanisms are generally described by non-linear stress relations and decrease of the elastic moduli due to microcrak opening and sliding. However, failure mode depends on confining pressure and ranges from axial splitting to shear localization. Here we report experiments on Westerly granite samples deformed under controlled upper crustal stress conditions in the laboratory. Experiments were conducted under triaxial loading (σ1>σ2=σ3) at confining pressures (σ3) ranging from 2 to 50 MPa (similar to upper crustal stress conditions) and at constant axial strain rate 10-5/s. Usual a dual gain system, a high frequency acoustic monitoring array recorded particles acceleration during macroscopic rupture of the intact specimen and premonitory background microseismicity. Secondly, acoustic sensors were used in an active way to measure the evolution of elastic wave velocities. In addition, we used an amplified strain gage to record the dynamic stress change during the dynamic rupture. Our preliminary results show that increasing confining pressure leads to the transition between axial cracks opening to shear localization. This result is supported by the moment tensor solutions of acoustic emissions and CT scan imaging of the post mortem sample. In addition, we systematically observe an exponential increase of the premonitory activity up to the shear failure of the sample. While the intensity of this precursory activity increase with the confining pressure in term of energy, the crack density leading to the failure of the sample is independent of the confinement. We show that the dynamic rupture occurs in only few microseconds, suggesting a rupture speed close to the shear wave velocity. In addition, the ratio between the stress drop and the peak of stress increases with the confinement. This result suggest that the weakening of faulting increases with the confinement. Finally, using both dynamic stress drop and axial displacement measurement, we show that the fracture energy increases with both confining pressure and seismic slip.

Geomorphic effects, flood power, and channel competence of a catastrophic flood in confined and unconfined reaches of the upper Lockyer valley, southeast Queensland, Australia

NASA Astrophysics Data System (ADS)

Thompson, Chris; Croke, Jacky

2013-09-01

Flooding is a persistent natural hazard, and even modest changes in future climate are believed to lead to large increases in flood magnitude. Previous studies of extreme floods have reported a range of geomorphic responses from negligible change to catastrophic channel change. This paper provides an assessment of the geomorphic effects of a rare, high magnitude event that occurred in the Lockyer valley, southeast Queensland in January 2011. The average return interval of the resulting flood was ~ 2000 years in the upper catchment and decreased to ~ 30 years downstream. A multitemporal LiDAR-derived DEM of Difference (DoD) is used to quantify morphological change in two study reaches with contrasting valley settings (confined and unconfined). Differences in geomorphic response between reaches are examined in the context of changes in flood power, channel competence and degree of valley confinement using a combination of one-dimensional (1-D) and two-dimensional (2-D) hydraulic modelling. Flood power peaked at 9800 W m- 2 along the confined reach and was 2-3 times lower along the unconfined reach. Results from the DoD confirm that the confined reach was net erosional, exporting ~ 287,000 m3 of sediment whilst the unconfined reach was net depositional gaining ~ 209,000 m3 of sediment, 70% of the amount exported from the upstream, confined reach. The major sources of eroded sediment in the confined reach were within channel benches and macrochannel banks resulting in a significant increase of channel width. In the unconfined reach, the benches and floodplains were the major loci for deposition, whilst the inner channel exhibited minor width increases. The presence of high stream power values, and resultant high erosion rates, within the confined reach is a function of the higher energy gradient of the steeper channel that is associated with knickpoint development. Dramatic differences in geomorphic responses were observed between the two adjacent reaches of contrasting valley configuration. The confined reach experienced large-scale erosion and reorganisation of the channel morphology that resulted in significantly different areal representations of the five geomorphic features classified in this study.

Fluorescent fluid interface position sensor

DOEpatents

Weiss, Jonathan D.

2004-02-17

A new fluid interface position sensor has been developed, which is capable of optically determining the location of an interface between an upper fluid and a lower fluid, the upper fluid having a larger refractive index than a lower fluid. The sensor functions by measurement, of fluorescence excited by an optical pump beam which is confined within a fluorescent waveguide where that waveguide is in optical contact with the lower fluid, but escapes from the fluorescent waveguide where that waveguide is in optical contact with the upper fluid.

Provenance of the Walash-Naopurdan back-arc-arc clastic sequences in the Iraqi Zagros Suture Zone

NASA Astrophysics Data System (ADS)

Ali, Sarmad A.; Sleabi, Rajaa S.; Talabani, Mohammad J. A.; Jones, Brian G.

2017-01-01

Marine clastic rocks occurring in the Walash and Naopurdan Groups in the Hasanbag and Qalander areas, Kurdistan region, Iraqi Zagros Suture Zone, are lithic arenites with high proportions of volcanic rock fragments. Geochemical classification of the Eocene Walash and Oligocene Naopurdan clastic rocks indicates that they were mainly derived from associated sub-alkaline basalt and andesitic basalt in back-arc and island arc tectonic settings. Major and trace element geochemical data reveal that the Naopurdan samples are chemically less mature than the Walash samples and both were subjected to moderate weathering. The seaway in the southern Neotethys Ocean was shallow during both Eocene and Oligocene permitting mixing of sediment from the volcanic arcs with sediment derived from the Arabian continental margin. The Walash and Naopurdan clastic rocks enhance an earlier tectonic model of the Zagros Suture Zone with their deposition occurring during the Eocene Walash calc-alkaline back-arc magmatism and Early Oligocene Naopurdan island arc magmatism in the final stages of intra-oceanic subduction before the Miocene closure and obduction of the Neotethys basin.

Field trip guidebook for the post-meeting field trip: The Central Appalachians

USGS Publications Warehouse

Taylor, John F.; Loch, James D.; Ganis, G. Robert; Repetski, John E.; Mitchell, Charles E.; Blackmer, Gale C.; Brezinski, David K.; Goldman, Daniel; Orndorff, Randall C.; Sell, Bryan K.

2015-01-01

The lower Paleozoic rocks to be examined on this trip through the central Appalachians represent an extreme range of depositional environments. The lithofacies we will examine range from pelagic radiolarian chert and interbedded mudstone that originated on the deep floor of the Iapetus Ocean, through mud cracked supratidal dolomitic laminites that formed during episodes of emergence of the long-lived Laurentian carbonate platform, to meandering fluvial conglomerate and interstratified overbank mudstone packages deposited in the latest stages of infilling of the Taconic foredeep. In many ways this field trip is about contrasts. The Upper Cambrian (Furongian) and Lower Ordovician deposits of the Sauk megasequence record deposition controlled primarily by eustatic sea level sea level fluctuations that influenced deposition along the passive, southern (Appalachian) margin of the paleocontinent of Laurentia. The only tectonic influence apparent in these passive margin deposits is the expected thickening of the carbonate stack toward the platform margin as compared to the thinner (and typically shallower) facies that formed farther in toward the paleoshoreline. Carbonates overwhelmingly dominate the passive margin succession. Clastic influx was minimal and consisted largely of eastward transport of clean cratonic sands across the platform from the adjacent inner detrital belt to the west during higher order (2nd and 3rd order) regressions.In contrast, Middle and Upper Ordovician deposits of the Tippecanoe megasequence record the strong influence of tectonics, specifically Iapetus closure. The first signal of this tectonic transformation was the arrival of arc-related ash beds that abound in the active margin carbonates. Subsequent intensification of Taconic orogenesis resulted in the foundering of the carbonate platform under the onslaught of fine siliciclastics arriving from offshore tectonic sources to the east, creating a deep marine flysch basin where graptolitic shale and sandstone turbidites accumulated. The foreland basin thus created would fill with progressively coarser and more shallow/proximal clastic facies through the Upper Ordovician, culminating in deposition of fluvial redbeds that cap the Taconic clastic wedge. Arguably the most controversial rocks within the Tippecanoe Sequence in this area are unusual, Lower Ordovician deep marine facies that are associated with the much younger flysch of the Martinsburg Formation in the Great Valley of eastern Pennsylvania. Long considered the erosional remnants of a Taconic-style thrust sheet, and referred to as the Hamburg Klippe, these deep marine deposits have recently been reinterpreted as olistostromal deposits that were introduced by gravity sliding into the flysch basin contemporaneous with Martinsburg deposition.Besides their constituent lithofacies, rocks of the Sauk and Tippecanoe megasequences also present a stark contrast in faunas. Cambrian and Lower Ordovician faunas predate the Great Ordovician Biodiversification Event (GOBE), a global event that saw unprecedented diversification within many major invertebrate groups (mollusks, corals, and bryozoans to name a few) that previously were only minor components of the marine fauna. Unfortunately, the much higher diversity of Middle and Upper Ordovician faunas wrought by the GOBE is somewhat muted in this region by the stresses introduced by conversion of the Appalachian shelf into a flysch basin. Another noteworthy difference between the Cambrian and Ordovician biota related to the paleogeographic setting of the rocks to be examined on this trip derives from their evolution in the shallow marine environments of Laurentia. Several shelf-wide extinctions decimated the shallow marine faunas of the Laurentian shelf through the late Cambrian producing stage-level biostratigraphic units known as biomeres. The biomere phenomenon is discussed in this guidebook and a few stops to examine Cambrian faunas and one biomere boundary extinction are included to provide contrast with stage boundary extinctions that occurred later, in the Ordovician, that lack the defining attributes of the biomere boundary extinctions. Again, it’s all about contrast.

Summary of hydrologic testing of the Floridan aquifer system at Hunter Army Airfield, Chatham County, Georgia

USGS Publications Warehouse

Williams, Lester J.

2010-01-01

A 1,168-foot deep test well was completed at Hunter Army Airfield in the summer of 2009 to investigate the potential of using the Lower Floridan aquifer as a source of water supply to satisfy increased needs as a result of base expansion and increased troop levels. The U.S. Geological Survey conducted hydrologic testing at the test site including flowmeter surveys, packer-slug tests, and aquifer tests of the Upper and Lower Floridan aquifers. Flowmeter surveys were completed at different stages of well construction to determine the depth and yield of water-bearing zones and to identify confining beds that separate the main producing aquifers. During a survey when the borehole was open to both the upper and lower aquifers, five water-bearing zones in the Upper Floridan aquifer supplied 83.5 percent of the total pumpage, and five water-bearing zones in the Lower Floridan aquifer supplied the remaining 16.5 percent. An upward gradient was indicated from the ambient flowmeter survey: 7.6 gallons per minute of groundwater was detected entering the borehole between 750 and 1,069 feet below land surface, then moved upward, and exited the borehole into lower-head zones between 333 and 527 feet below land surface. During a survey of the completed Lower Floridan well, six distinct water-producing zones were identified; one 17-foot-thick zone at 768-785 feet below land surface yielded 47.9 percent of the total pumpage while the remaining five zones yielded between 2 and 15 percent each. The thickness and hydrologic properties of the confining unit separating the Upper and Lower Floridan aquifers were determined from packer tests and flowmeter surveys. This confining unit, which is composed of rocks of Middle Eocene age, is approximately 160 feet thick with horizontal hydraulic conductivities determined from four slug tests to range from 0.2 to 3 feet per day. Results of two separate slug tests within the middle confining unit were both 2 feet per day. Aquifer testing indicated the Upper Floridan aquifer had a transmissivity of 40,000 feet squared per day, and the Lower Floridan aquifer had a transmissivity of 10,000 feet squared per day. An aquifer test conducted on the combined aquifer system, when the test well was open from 333 to 1,112 feet, gave a transmissivity of 50,000 feet squared per day. Additionally, during the 72-hour test of the Lower Floridan aquifer, a drawdown response was observed in the Upper Floridan aquifer wells.

Stratigraphy of the Sarkisla area, Sivas basin, eastern central Anatolia

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

Bilgic, T.; Sumengen, M.; Terlemez, I.

1988-08-01

The stratigraphy of the Sarkisla area, southeastern Central Anatolian Massif, is characterized by a succession of rock units ranging from late Paleocene to Pliocene in age. The Caldag group mostly consists of deep-water units and forms the base of the Tertiary rocks. However, its relation to the basement rocks is not observed in the area. This group is represented by late Paleocene-Lutetian-age turbiditic pyroclastics and limestones, andesitic lavas and pyroclastics topped with reefal limestones, and turbiditic limestones and pyroclastics alternating with limestone blocks. During Lutetian to early Priabonian time, shallow marine clastics were deposited along the southern margin of themore » basin, while continental clastics and platform limestones accumulated along the northern margin. Late Priabonian to early Oligocene time is represented by gypsiferous deposits followed by late Oligocene-age fluvial clastics. The gypsiferous deposits conformably overlie the shallow marine formations but rest on the Caldag group unconformably. During early to middle Miocene time, alternating lacustrine limestones, gypsum, and basalts formed on the fluvial clastics; to the north, basalts formed on the platform limestones. The uppermost sequence of the basin, composed of Tortonian-early Pliocene-age fluvial clastics, lacustrine limestones, and fan deposits, unconformably overlies the older formations. The stratigraphy of the study area is similar to the Ulukisla basin, southwestern Central Anatolian Massif. Therefore, this basin can be considered to be the prolongation of the Ulukisla basin offset by the Ecemis fault.« less

Interpreting the Holocene fluctuations of Quelccaya Ice Cap, Peru: using a combination of glacial and non-glacial lake records

NASA Astrophysics Data System (ADS)

Stroup, J. S.; Kelly, M. A.; Lowell, T. V.; Smith, C.; Beal, S. A., Jr.; Tapia, P. M.

2016-12-01

The past fluctuations of Quelccaya Ice Cap (QIC) are an indicator of tropical paleoclimate. At QIC, ice core and glacial geological records provide late Holocene climate constraints. However, early and middle Holocene QIC fluctuations are less well-known. To interpret past QIC fluctuations, we present Holocene-long lake sediment records from Challpacocha, a lake fed by QIC meltwater, and Yanacocha, a lake that has not received meltwater during the Holocene. To assess the clastic sediment delivered to Challpacocha by QIC meltwater, we compare visual stratigraphy, X-ray fluorescence chemistry, grainsize, loss on ignition and clastic flux records from both lakes (additional Yanacocha proxies are presented by Axford et al. (this meeting, abstract 157985)). We compare the meltwater derived clastic sediment record from Challpacocha with moraine and stratigraphic records of past ice extents during the late Holocene. This comparison indicates that clastic sediment flux in Challpacocha increased during QIC recession and decreased during QIC advance, or significantly reduced QIC extent. We then use the Challpacocha clastic sediment record to interpret early and middle Holocene QIC fluctuations. Based on the Challpacocha sediment record, combined with prior work, we suggest that from 11 to 6.5 ka QIC was similar to or smaller than its late Holocene extent. From 6.9 to 6.5 ka QIC may have been absent from the landscape. At 3-2.4 and 0.62-0.31 ka QIC experienced the most extensive Holocene fluctuations. We compare the clastic sediment fluxes from Challpacocha and Pacococha (a nearby lake fed by QIC; Rodbell et al., 2008) to infer QIC expansion between 6.5-5 ka. This is supported by 14C ages of in-situ subfossil plants which indicate ice advance at 6.3-4.7 ka (Thompson et al., 2006, 2013; Buffen et al., 2009). Our study highlights the value of using multiple datasets to improve lake sediment record interpretations.

Summary of hydrologic testing of the Floridan aquifer system at Fort Stewart, Georgia

USGS Publications Warehouse

Gonthier, Gerard

2011-01-01

Flowmeter surveys at the study site indicate several permeable zones within the Floridan aquifer system. The Upper Floridan aquifer is composed of two water-bearing zones-the upper zone and the lower zone. The upper zone extends from 520 to 650 feet below land surface, contributes 96 percent of the total flow, and is more permeable than the lower zone, which extends from 650 to 705 feet below land surface and contributes the remaining 4 percent of the flow. The Lower Floridan aquifer consists of three zones at depths of 912-947, 1,090-1,139, and 1,211-1,250 feet below land surface that are inter-layered with three less-permeable zones. The Lower Floridan confining unit includes a permeable zone that extends from 793 to 822 feet below land surface. Horizontal hydraulic conductivity values of the Lower Floridan confining unit derived from slug tests within four packer-isolated intervals were from 2 to 20 feet per day, with a high value of 70 feet per day obtained for one of the intervals. Aquifer testing, using analytical techniques and model simulation, indicated the Upper Floridan aquifer had a transmissivity of about 100,000 feet squared per day, and the Lower Floridan aquifer had a transmissivity of 7,000 feet squared per day. Flowmeter surveys, slug tests within packer-isolated intervals, and parameter-estimation results indicate that the hydraulic properties of the Lower Floridan confining unit are similar to those of the Lower Floridan aquifer. Water-level data, for each aquifer test, were filtered for external influences such as barometric pressure, earth-tide effects, and long-term trends to enable detection of small water-level responses to aquifer-test pumping of less than 1 foot. During a 72-hour aquifer test of the Lower Floridan aquifer, a drawdown response of 0.3 to 0.4 foot was observed in two Upper Floridan aquifer wells, one of which was more than 1 mile away from the pumped well.

Provenance and geochronological insights into Late Cretaceous-Paleogene foreland basin development in the Subandean Zone and Oriente Basin of Ecuador

NASA Astrophysics Data System (ADS)

Gutierrez, E. G.; Horton, B. K.; Vallejo, C.

2017-12-01

The tectonic history of the Oriente foreland basin and adjacent Subandean Zone of Ecuador during contractional mountain building in the northern Andes can be revealed through integrated stratigraphic, geochronological, structural, and provenance analyses of clastic sediments deposited during orogenesis. We present new maximum depositional ages and a comprehensive provenance analysis for key stratigraphic units deposited in the western (proximal) Oriente Basin. Detrital zircon U-Pb ages were obtained from Upper Cretaceous and Cenozoic clastic formations from exposures in the Subandean Zone. The sampled stratigraphic intervals span critical timeframes during orogenesis in the Ecuadorian Andes. Cenozoic formations have poorly defined chronostratigraphic relationships and are therefore a primary target of this study. In addition, the newly acquired U-Pb age spectra allow clear identification of the various sediment source regions that fed the system during distinct depositional phases. Maximum depositional ages (MDA) were obtained for five samples from three formations: the Tena (MDA=69.6 Ma), Chalcana (MDA=29.3 Ma), and Arajuno (MDA= 17.1, 14.2, 12.8 Ma) Formations, placing them in the Maastrichtian, early Oligocene, and early-middle Miocene, respectively. Detrital zircon U-Pb ages identify clear signatures of at least four different sources: craton (1600-1300 Ma, 1250-900 Ma), Eastern Cordillera fold-thrust belt (600-450 Ma, 250-145 Ma), Western Cordillera magmatic arc (<88 Ma), and recycling of cratonic material from the Eastern Cordillera. The U-Pb age spectra of the Upper Cretaceous-Paleogene type sections allow us to recognize variations in the contribution of each recognized source over time. We identify recycled material with two dominant peak ages (1250-900 Ma and 600-450 Ma), material derived from the adjacent uplifted orogen or recycled from foredeep sediments incorporated into the deforming wedge. Finally, an apparent unroofing event is inferred from a 250-145 Ma age peak in the Plio-Pleistocene Mesa-Mera Formation revealing the persistent shortening deformation influencing the structural configuration and sediment dispersal patterns of the Oriente Basin and Subandean Zone.

A Lower Carboniferous two-stage extensional basin along the Avalon-Meguma terrane boundary: Evidence from southeastern Isle Madame, Nova Scotia

USGS Publications Warehouse

Force, E.R.; Barr, S.M.

2006-01-01

Anomalously thick and coarse clastic sedimentary successions, including over 5000 m of conglomerate, are exposed on Isle Madame off the southern coast of Cape Breton Island. Two steeply to moderately dipping stratigraphic packages are recognized: one involving Horton and lower Windsor groups (Tournasian-Visean); the other involving upper Windsor and Mabou (Visean-Namurian) groups. Also anomalous on Isle Madame are three long narrow belts of "basement" rocks, together with voluminous chloritic microbreccia and minor semi-ductile mylonite, which are separated from the conglomerate-dominated successions by faults. The angular relations between the cataclastic rocks and the conglomerate units, combined with the presence of cataclasite clasts in the conglomerate units and evidence of dip-slip faults within the basin, suggest an extensional setting, where listric normal faults outline detachment allochthons. Allochthon geometry requires two stages of extension, the older stage completed in early Windsor Group time and including most of the island, and the more local younger stage completed in Mabou Group time. Domino-style upper-plate faulting in the younger stage locally repeated the older detachment relation of basement and conglomerate to form the observed narrow belts. Re-rotation of older successions in the younger stage also locally overturned the Horton Group. These features developed within a broad zone of Carboniferous dextral transcurrent faulting between already-docked Avalon and Meguma terranes. Sites of transpression and transtension alternated along the Cobequid-Chedabucto fault zone that separated these terranes. The earlier extensional features in Isle Madame likely represent the northern headwall and associated clastic debris of a pull-apart or other type of transtensional basin developed along part of this fault zone that had become listric; they were repeated and exposed by being up-ended in the second stage of extension, also on listric faults. The two-stage history on Isle Madame exposes the deeper parts of one of the Horton-age extensional basins of the Maritimes, others of which have been described as half-grabens based on their shallower exposures.

New geological data of New Siberian Archipelago

NASA Astrophysics Data System (ADS)

Sobolev, Nikolay; Petrov, Evgeniy

2014-05-01

The area of New Siberian Archipelago (NSA) encompasses different tectonic blocks is a clue for reconstruction of geological structure and geodynamic evolution of East Arctic. According to palaeomagnetic study two parts of the archipelago - Bennett and Anjou Islands formed a single continental block at least from the Early Palaeozoic. Isotope dating of De Long Islands igneous and sedimentary rocks suggests Neoproterozoic (Baikalian) age of its basement. The De Long platform sedimentary cover may be subdivided into two complexes: (1) intermediate of PZ-J variously deformed and metamorphosed rocks and (2) K-KZ of weakly lithified sediments. The former complex comprises the Cambrian riftogenic volcanic-clastic member which overlain by Cambrian-Ordovician turbiditic sequence, deposited on a continental margin. This Lower Palaeozoic complex is unconformably overlain by Early Cretaceous (K-Ar age of c.120 Ma) basalts with HALIP petrochemical affinities. In Anjou Islands the intermediate sedimentary complex encompasses the lower Ordovician -Lower Carboniferous sequence of shallow-marine limestone and subordinate dolomite, mudstone and sandstone that bear fossils characteristic of the Siberian biogeographic province. The upper Mid Carboniferous - Jurassic part is dominated by shallow-marine clastic sediments, mainly clays. The K-KZ complex rests upon the lower one with angular unconformity and consists mainly of coal-bearing clastic sediments with rhyolite lavas and tuffs in the bottom (117-110 Ma by K-Ar) while the complexe's upper part contains intraplate alkalic basalt and Neogene-Quaternary limburgite. The De-Long-Anjou block's features of geology and evolution resemble those of Wrangel Island located some 1000 km eastward. The Laptev Sea shelf outcrops in intrashelf rises (Belkovsky and Stolbovoy Islands) where its geology and structure may be observed directly. On Belkovsky Island non-dislocated Oligocene-Miocene sedimentary cover of littoral-marine coal-bearing unconformably overlies folded basement. The latter encompasses two sedimentary units: the Middle Devonian shallow-marine carbonate and Late-Devonian-Permian olistostrome - flysch deposited in transitional environment from carbonate platform to passive margin. Dating of detrital zircons suggests the Siberian Platform and Taimyr-Severnaya Zemlya areas as the most possible provenance. The magmatic activity on Belkovsky Island resulted in formation of Early Triassic gabbro-dolerite similar to the Siberian Platform traps. Proximity of Belkovsky Island to the north of Verkhoyansk foldbelt allows continuation of the latter into the Laptev Sea shelf. The geology of Bolshoy Lyakhovsky Island is discrepant from the rest of the NSA. In the south of Bolshoy Lyakhovsky Island the ophiolite crops complex out: it is composed of tectonic melange of serpentinized peridotite, bandedf gabbro, pillow-basalt, and pelagic sediments (black shales and cherts). All the rocks underwent epidot - amphibolite, glaucophane and greenschist facies metamorphism. The ophiolite is intruded by various in composition igneous massifs - from gabbro-diorite to leuco-granite, which occurred at 110-120 Ma. The Bolshoy Lyakhovsky Island structure is thought to be a westerly continuation of the South Anui suture of Chukchi.

The combined effects of eustasy, tectonism, and clastic influx on the development of Pennsylvanian cyclic carbonates, southern Sangre de Cristo Mountains, New Mexico

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

Gong Shouyeh; Humphrey, J.D.

1991-03-01

Pennsylvania cyclothems are well documented on stable continental shelves and the cyclicity has generally been attributed to glacio-eustasy. As a contrast, Atokan-Desmoinesian cyclic carbonates of the southern Sangre de Cristo Mountains developed in a tectonically active foreland basin, formed by thrusting along the Picuris-Pecos fault during early Pennsylvanian time. Strata exposed in two sections (Dalton Bluff, 260 m; Johnson Mesa, 340 m) are characterized by (1) shallowing-upward cycles, (2) cycles of variable thickness (5-20 m), (3) incomplete cycles, (4) cycles interrupted by terrigenous clastic input, and (5) noncyclic intervals. Allocyclic mechanisms alone cannot fully explain these observations; the authors hereinmore » propose that a complex interplay among eustasy, tectonism, and clastic sediment supply were responsible for the observed cycles. Lithofacies analysis indicates that location within the foreland basin played a significant role in cycle attributes. In the deeper portions of the basin (e.g., Dalton Bluff), an idealized cycle, from base to top consists of (1) shale/marl facies, (2) brachiopod wackestone facies, (3) phylloid algal facies, and (4) marine clastic facies. No evidence for subaerial exposure of cycle caps is noted. In contrast, in shallow portions of the basin near the forebulge (e.g., Johnson Mesa) the marine clastic facies is substituted by crinoidal grainstone/packstone facies that is capped by subaerial exposure surface. Each of the two cycles displays an overall grand (lower order) shallowing-upward cycle. This grand cycle developed as sediments infilled the initially starved foreland basin.« less

Tektite-bearing, deep-water clastic unit at the Cretaceous-Tertiary boundary in northeastern Mexico

NASA Technical Reports Server (NTRS)

Smit, J.; Montanari, A.; Swinburne, N. H.; Alvarez, W.; Hildebrand, A. R.; Margolis, S. V.; Claeys, P.; Lowrie, W.; Asaro, F.

1992-01-01

The hypothesis of Cretaceous-Tertiary (K-T) boundary impact on Yucatan, Mexico, predicts that nearby sites should show evidence of proximal impact ejecta and disturbance by giant waves. An outcrop along the Arroyo el Mimbral in northeastern Mexico contains a layered clastic unit up to 3 m thick that interrupts a biostratigraphically complete pelagic-marl sequence deposited at more than 400 m water depth. The marls were found to be unsuitable for determining magnetostratigraphy, but foraminiferal biostratigraphy places the clastic unit precisely at the K-T boundary. We interpret this clastic unit as the deposit of a megawave or tsunami produced by an extraterrestrial impact. The clastic unit comprises three main subunits. (1) The basal "spherule bed" contains glass in the form of tektites and microtektites, glass spherules replaced by chlorite-smectite and calcite, and quartz grains showing probable shock features. This bed is interpreted as a channelized deposit of proximal ejecta. (2) A set of lenticular, massive, graded "laminated beds" contains intraclasts and abundant plant debris, and may be the result of megawave backwash that carried coarse debris from shallow parts of the continental margin into deeper water. (3) At the top, several thin "ripple beds" composed of fine sand are separated by clay drapes; they are interpreted as deposits of oscillating currents, perhaps a seiche. An iridium anomaly (921 +/- 23 pg/g) is observed at the top of the ripple beds. Our observations at the Mimbral locality support the hypothesis of a K-T impact on nearby Yucatan.

Provenance of Mesozoic clastic rocks within the Bangong-Nujiang suture zone, central Tibet: Implications for the age of the initial Lhasa-Qiangtang collision

NASA Astrophysics Data System (ADS)

Li, Shun; Guilmette, Carl; Ding, Lin; Xu, Qiang; Fu, Jia-Jun; Yue, Ya-Hui

2017-10-01

The Bangong-Nujiang suture zone, separating the Lhasa and Qiangtang blocks of the Tibetan Plateau, is marked by remnants of the Bangong-Nujiang oceanic basin. In the Gaize area of central Tibet, Mesozoic sedimentary strata recording the evolution of the basin and subsequent collision between these two blocks include the Upper Triassic-Lower Jurassic turbidites of the Mugagangri Group, the Upper Jurassic-Lower Cretaceous sandstone-dominated Wuga and Shamuluo formations, and the Upper Cretaceous molasse deposits of the Jingzhushan Formation. The Shamuluo and Jingzhushan formations rest unconformably on the underlying Mugagangri Group and Wuga Formation, respectively. In this contribution, we analyze petrographic components of sandstones and U-Pb-Hf isotopic compositions of detrital zircons from the Wuga and Jingzhushan formations for the first time. Based on the youngest detrital zircon ages, the maximum depositional ages of the Wuga and Jingzhushan formations are suggested to be ∼147-150 Ma and ∼79-91 Ma, respectively. Petrographic and isotopic results indicate that sediments in the Wuga Formation were mainly sourced from the accretionary complex (preserved as the Mugagangri Group) in the north, while sediments in the Jingzhushan Formation have mixed sources from the Lhasa block, the Qiangtang block and the intervening suture zone. Provenance analysis, together with regional data, suggests that the Upper Jurassic-Lower Cretaceous Wuga and Shamuluo formations were deposited in a peripheral foreland basin and a residual-sea basin, respectively, in response to the Lhasa-Qiangtang collision, whereas the Upper Cretaceous Jingzhushan Formation reflects continental molasse deposition during the post-collisional stage. The development of the peripheral foreland basin evidenced by deposition of the Wuga Formation reveals that the age of the initial Lhasa-Qiangtang collision might be the latest Jurassic (∼150 Ma).

Complex facies relationships and regional stratigraphy of the Mississippian Ste. Genevieve, Paoli, and Aux Vases Formations, Illinois basin: A major hydrocarbon-producing interval

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

Cole, R.D.; Nelson, W.J.

1993-03-01

The Mississippian Ste. Genevieve and Paoli Limestones and sandstones of the Aux Vases Formation are lateral facies of one another. This interpretation is based on comprehensive investigations of outcrops, and selected cores, samples of well cuttings, and geophysical logs conducted over a period of four years. Both units exhibit similar sedimentological characteristics and represent open marine, shallow subtidal, and intertidal environments. The presence of low-angle cross-laminae, ripple- and plane-laminae, climbing ripples, and ooid shoals suggest most deposition occurred under low energy conditions. Lenticular, channel-like scour and fill structures that contain both fine-grained quartz sand and abraded, disarticulated fossil fragments indicatemore » localized higher energy deposition. The authors studies indicate that siliciclastic vs. carbonate deposition was controlled strictly by available sediment, and not by regressive (siliciclastic) and transgressive (carbonate) events, as inferred by previous workers. This conclusion is based on lateral facies relationships, and the supplanting of carbonates by clastics occurring in the upper part of the Ste. Genevieve through the middle part of the Paoli. The Aux Vases is thickest, coarsest, and least mature in the northwestern part of the Illinois Basin, and pinches out to the southeast. This implies a northwesterly source for clastics, perhaps the Transcontinental Arch. After early Chesterian time, the Transcontinental Arch apparently supplied little or no sediment to any flanking basin. The Ste. Genevieve, Paoli, and Aux Vases are major oil-producing units in the Illinois Basin. New understanding of regional relationships should enhance exploratory success and improve recovery from established fields.« less

Benthic foraminifera at the Cretaceous-Tertiary boundary around the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Alegret, Laia; Molina, Eustoquio; Thomas, Ellen

2001-10-01

Cretaceous-Tertiary (K-T) boundary sections in northeastern Mexico contain marly formations separated by a controversial clastic unit. Benthic foraminifera in seven sections indicate middle and lower bathyal depths of deposition for the marls, with the exception of the upper bathyal northernmost section. Mixed neritic-bathyal faunas were present in the clastic unit, indicating redeposition in the deep basin by mass-wasting processes resulting from the K-T bolide impact in the Gulf of Mexico. Benthic foraminifera in the Mexican sections, and at other deep-sea locations, were not subject to major extinction at the time of impact, but there were temporary changes in assemblage composition. Benthic faunas indicate well- oxygenated bottom waters and mesotrophic conditions during the late Maastrichtian and increased food supply during the latest Maastrichtian. The food supply decreased drastically just after the K-T boundary, possibly because of the collapse of surface productivity. Cretaceous and early Paleogene benthic foraminifera, however, did not exhibit the benthic-pelagic coupling of present-day faunas, as documented by the lack of significant extinction at the K-T collapse of surface productivity. Much of the food supplied to the benthic faunas along this continental margin might have been refractory material transported from land or shallow coastal regions. The decrease in food supply at the K-T boundary might be associated with the processes of mass wasting, which removed surface, food-rich sediment. Benthic faunas show a staggered pattern of faunal recovery in the lowermost Paleogene, consistent with a staged recovery of the vertical organic flux but also with a gradual buildup of organic matter in the sediment.

Provenance of sandstones in the Golconda terrane, north central Nevada

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

Jones, E.A.

1991-02-01

The upper Paleozoic Golconda terrane of north-central Nevada is a composite of several structurally bounded subterranes made of clastic, volcanic, and carbonate rocks. The clastic rocks provide important clues for the interpretation of the provenance and paleogeographic settings of the different lithologic assemblages found in these subterranes. Two petrographically distinct sandstones are identified in the Golconda terrane in the Osgood Mountains and the Hot springs Range of north-central Nevada. The sandstone of the Mississippian Farrel Canyon Formation, part of the Dry Hills subterrane, is characterized by quartzose and sedimentary and lithic-rich clasts with a small feldspar component. in contrast, themore » sandstone of the Permian Poverty Peak (II) subterrane is a silty quartzarenite with no lithic component, and a very limited feldspar component. The sandstone of the Farrel Canyon Formation is similar to nonvolcanic sandstones reported from elsewhere in the Golconda terrane. Modal data reflect a provenance of a recycled orogen and permit the interpretation that it could have been derived from the antler orogen as has been proposed for other sandstones of the golconda terrane. The sandstone of the Poverty Peak (II) subterrane is more mature than any of the other sandstones in either the Golconda terrane, the Antler overlap sequence, or the Antler foreland basin sequence. Modal data put the Poverty Peak (II) sandstone in the continental block provenance category. The distinct extrabasinal provenances represented in these different sandstones support the idea that the Golconda basin was made up of complex paleogeographic settings, which included multiple sources of extrabasinal sediment.« less

Radiocarbon dating of dissolved inorganic carbon in groundwater from confined parts of the Upper Floridan aquifer, Florida, USA

USGS Publications Warehouse

Plummer, Niel; Sprinkle, C.L.

2001-01-01

Geochemical reaction models were evaluated to improve radiocarbon dating of dissolved inorganic carbon (DIC) in groundwater from confined parts of the Upper Floridan aquifer in central and northeastern Florida, USA. The predominant geochemical reactions affecting the 14C activity of DIC include (1) dissolution of dolomite and anhydrite with calcite precipitation (dedolomitization), (2) sulfate reduction accompanying microbial degradation of organic carbon, (3) recrystallization of calcite (isotopic exchange), and (4) mixing of fresh water with as much as 7% saline water in some coastal areas. The calculated cumulative net mineral transfers are negligibly small in upgradient parts of the aquifer and increase significantly in downgradient parts of the aquifer, reflecting, at least in part, upward leakage from the Lower Floridan aquifer and circulation that contacted middle confining units in the Floridan aquifer system. The adjusted radiocarbon ages are independent of flow path and represent travel times of water from the recharge area to the sample point in the aquifer. Downgradient from Polk City (adjusted age 1.7 ka) and Keystone Heights (adjusted age 0.4 ka), 14 of the 22 waters have adjusted 14C ages of 20-30 ka, indicating that most of the fresh-water resource in the Upper Floridan aquifer today was recharged during the last glacial period. All of the paleowaters are enriched in 18O and 2H relative to modern infiltration, with maximum enrichment in ??18O of approximately 2.0%o.

Petroleum geology and resources of the Amu-Darya basin, Turkmenistan, Uzbekistan, Afghanistan, and Iran

USGS Publications Warehouse

Ulmishek, Gregory F.

2004-01-01

The Amu-Darya basin is a highly productive petroleum province in Turkmenistan and Uzbekistan (former Soviet Union), extending southwestward into Iran and southeastward into Afghanistan. The basin underlies deserts and semideserts north of the high ridges of the Kopet-Dag and Bande-Turkestan Mountains. On the northwest, the basin boundary crosses the crest of the Karakum regional structural high, and on the north the basin is bounded by the shallow basement of the Kyzylkum high. On the east, the Amu-Darya basin is separated by the buried southeast spur of the Gissar Range from the Afghan-Tajik basin, which is deformed into a series of north-south-trending synclinoria and anticlinoria. The separation of the two basins occurred during the Neogene Alpine orogeny; earlier, they were parts of a single sedimentary province. The basement of the Amu-Darya basin is a Hercynian accreted terrane composed of deformed and commonly metamorphosed Paleozoic rocks. These rocks are overlain by rift grabens filled with Upper Permian-Triassic rocks that are strongly compacted and diagenetically altered. This taphrogenic sequence, also considered to be a part of the economic basement, is overlain by thick Lower to Middle Jurassic, largely continental, coal-bearing rocks. The overlying Callovian-Oxfordian rocks are primarily carbonates. A deep-water basin surrounded by shallow shelves with reefs along their margins was formed during this time and reached its maximum topographic expression in the late Oxfordian. In Kimmeridgian-Tithonian time, the basin was filled with thick evaporites of the Gaurdak Formation. The Cretaceous-Paleogene sequence is composed chiefly of marine clastic rocks with carbonate intervals prominent in the Valanginian, Barremian, Maastrichtian, and Paleocene stratigraphic units. In Neogene time, the Alpine orogeny on the basin periphery resulted in deposition of continental clastics, initiation of new and rejuvenation of old faults, and formation of most structural traps. A single total petroleum system is identified in the Amu-Darya basin. The system is primarily gas prone. Discovered gas reserves are listed by Petroconsultants (1996) at about 230 trillion cubic feet, but recent discoveries and recent reserve estimates in older fields should increase this number by 40 to 50 trillion cubic feet. Reserves of liquid hydrocarbons (oil and condensate) are comparatively small, less than 2 billion barrels. Most of the gas reserves are concentrated in two stratigraphic intervals, Upper Jurassic carbonates and Neocomian clastics, each of which contains about one-half of the reserves. Reserves of other stratigraphic units?from Middle Jurassic to Paleogene in age?are relatively small. Source rocks for the gas are the Lower to Middle Jurassic clastics and coal and Oxfordian basinal black shales in the east-central part of the basin. The latter is probably responsible for the oil legs and much of the condensate in gas pools. Throughout most of the basin both source-rock units are presently in the gas-window zone. Traps are structural, paleogeomorphic, and stratigraphic, as well as a combination of these types. The giant Dauletabad field is in a combination trap with an essential hydrodynamic component. Four assessment units were identified in the total petroleum system. One unit in the northeastern, northern, and northwestern marginal areas of the basin and another in the southern marginal area are characterized by wide vertical distribution of hydrocarbon pools in Middle Jurassic to Paleocene rocks and the absence of the salt of the Gaurdak Formation. The other two assessment units are stratigraphically stacked; they occupy the central area of the basin and are separated by the regional undeformed salt seal of the Gaurdak Formation. The largest part of undiscovered hydrocarbon resources of the Amu-Darya basin is expected in older of these assessment units. The mean value of total assessed resources of the Amu-Darya basin is estimated

Petroleum geology and resources of the North Ustyurt Basin, Kazakhstan and Uzbekistan

USGS Publications Warehouse

Ulmishek, Gregory F.

2001-01-01

The triangular-shaped North Ustyurt basin is located between the Caspian Sea and the Aral Lake in Kazakhstan and Uzbekistan and extends offshore both on the west and east. Along all its sides, the basin is bounded by the late Paleozoic and Triassic foldbelts that are partially overlain by Jurassic and younger rocks. The basin formed on a cratonic microcontinental block that was accreted northward to the Russian craton in Visean or Early Permian time. Continental collision and deformation along the southern and eastern basin margins occurred in Early Permian time. In Late Triassic time, the basin was subjected to strong compression that resulted in intrabasinal thrusting and faulting. Jurassic-Tertiary, mostly clastic rocks several hundred meters to 5 km thick overlie an older sequence of Devonian?Middle Carboniferous carbonates, Upper Precambrian massifs and deformed Caledonian foldbelts. The Carboniferous?Lower Permian clastics, carbonates, and volca-basement is at depths from 5.5 km on the highest uplifts to 11 nics, and Upper Permian?Triassic continental clastic rocks, pri-km in the deepest depressions. marily red beds. Paleogeographic conditions of sedimentation, Three total petroleum systems are identified in the basin. the distribution of rock types, and the thicknesses of pre-Triassic Combined volumes of discovered hydrocarbons in these sysstratigraphic units are poorly known because the rocks have been tems are nearly 2.4 billion barrels of oil and 2.4 trillion cubic penetrated by only a few wells in the western and eastern basin feet of gas. Almost all of the oil reserves are in the Buzachi Arch areas. The basement probably is heterogeneous; it includes and Surrounding Areas Composite Total Petroleum System in 2 Petroleum Geology, Resources?North Ustyurt Basin, Kazakhstan and Uzbekistan the western part of the basin. Oil pools are in shallow Jurassic and Neocomian sandstone reservoirs, in structural traps. Source rocks are absent in the total petroleum system area; therefore, the oil could have migrated from the adjacent North Caspian basin. The North Ustyurt Jurassic Total Petroleum System encompasses the rest of the basin area and includes Jurassic and younger rocks. Several oil and gas fields have been discovered in this total petroleum system. Oil accumulations are in Jurassic clastic reservoirs, in structural traps at depths of 2.5?3 km. Source rocks for the oil are lacustrine beds and coals in the continental Jurassic sequence. Gas fields are in shallow Eocene sandstones in the northern part of the total petroleum system. The origin of the gas is unknown. The North Ustyurt Paleozoic Total Petroleum System stratigraphically underlies the North Ustyurt Jurassic system and occupies the same geographic area. The total petroleum system is almost unexplored. Two commercial flows of gas and several oil and gas shows have been tested in Carboniferous shelf carbonates in the eastern part of the total petroleum system. Source rocks probably are adjacent Carboniferous deep-water facies interpreted from seismic data. The western extent of the total petroleum system is conjectural. Almost all exploration drilling in the North Ustyurt basin has been limited to Jurassic and younger targets. The underlying Paleozoic-Triassic sequence is poorly known and completely unexplored. No wells have been drilled in offshore parts of the basin. Each of three total petroleum systems was assessed as a single assessment unit. Undiscovered resources of the basin are small to moderate. Most of the undiscovered oil probably will be discovered in Jurassic and Neocomian stratigraphic and structural traps on the Buzachi arch, especially on its undrilled off-shore extension. Most of the gas discoveries are expected to be in Paleozoic carbonate reservoirs in the eastern part of the basin.

Unusual occurrence of some sedimentary structures and their significance in Jurassic transgressive clastic successions of Northern Ethiopia

NASA Astrophysics Data System (ADS)

Dubey, N.; Bheemalingeswara, K.

2009-04-01

Mesozoic sedimentary successions produced by marine transgression and regression of sea in northeastern part of Africa are well preserved in Mekelle basin of Ethiopia. Here, a typical second order sequence is well developed and preserved overlying the Precambrian basement rocks or patchy Palaeozoic sedimentary successions. Initiation of Mesozoic sedimentation in Mekelle basin has started with deposition of Adigrat Sandstone Formation (ASF). It is a retrogradational succession of siliciclastics in coastline/beach environment due to transgression of sea from southeast. ASF is followed by Antallo Limestone Formation (ALF)- an aggradational succession of carbonates in tidal flat environment; Agula Shale/Mudstone Formation (AMF); and Upper/Ambaradom Sandstone Formation (USF)- a progradational succession formed during regression in ascending order (Dubey et al., 2007). AMF is deposited in a lagoonal evaporatic environment whereas USF in a fluvial coastal margin. ASF is an aggregate of cyclically stacked two lithologies ASF1 and ASF2 produced by sea-level rise and fall of a lower order mini-cycle. ASF1 is a thick, multistoried, pink to red, friable, medium to fine grained, cross-bedded sandstone deposited in a high energy environment. ASF2 is a thin, hard and maroon colored iron-rich mudstone (ironstones) deposited in a low energy environment. ASF1 has resulted during regressive phase of the mini-cycle when rate of sedimentation was extremely high due to abundant coarser clastic supply from land to the coastal area. On the other hand, ASF2 has resulted during transgressive phase of the mini-cycle which restricted the supply of the coarser clastic to the coastal area and deposited the muddy ferruginous sediments in low energy offshore part of the basin where sedimentation rate was very low. Apart from these two major lithologies, there are also few other minor lithologies like fine-grained white sandstone, carbonate (as bands), claystone and mudstone present in ASF. ASF is a well developed lithostratigraphic unit of northern Ethiopia and represents the Jurassic transgressive clastic succession of Mekelle basin. The physical and biogenic sedimentary structures reported in this paper are observed from the terminal part of ASF. Their occurrence is unusual, rare, unknown so far and unreported. It includes (i) mud cracks (including their casts filled with overlying lithology) representing subaerial exposure which is unusual during transgressive phase, (ii) vertical traces of Skolithos burrows in ASF2 produced by suspension feeders in high energy environment of deposition (Dubey et al., 2007), (iii) tiny bivalve moulds and casts (external- and internal-moulds) of body fossils, and (iv) elliptical negative epirelief (potato shaped empty depressions - external moulds of eggs or nodules?). Fifty two such randomly oriented external moulds are noticed within 2 m2 area on an upper bedding plane of thin, white and fine- grained sandstone. Their in- fills are missing/removed as they are present on a gently dipping bed. Therefore, it is difficult to ascertain their biogenic (egg) or abiogenic (nodule) origin. Their detail investigation is under progress. Since ASF developed during marine transgression, presence of mud cracks in its terminal part indicates subaerial exposure. This provides suitable sites for nesting eggs (reptile?) in wet sands. Removal of such preserved eggs can provide potato depressions. Though it is difficult to relate these moulds to the eggs because of the missing in-fills, their shape, size and restricted occurrence supports biogenic origin. Reference Dubey, N., Bheemalingeswara, K. and Tadesse, N. (2007). Sedimentology and lithostratigraphy of the Mesozoic successions of Mekelle Basin, Ethiopia, Norteastern Africa. Geophysical Research Abstracts, Vol.9, 11471. (SRef-ID: 1607-7962/gra/EGU2007-A-11471).

Bounds on quantum confinement effects in metal nanoparticles

NASA Astrophysics Data System (ADS)

Blackman, G. Neal; Genov, Dentcho A.

2018-03-01

Quantum size effects on the permittivity of metal nanoparticles are investigated using the quantum box model. Explicit upper and lower bounds are derived for the permittivity and relaxation rates due to quantum confinement effects. These bounds are verified numerically, and the size dependence and frequency dependence of the empirical Drude size parameter is extracted from the model. Results suggest that the common practice of empirically modifying the dielectric function can lead to inaccurate predictions for highly uniform distributions of finite-sized particles.

Palaeoenvironmental reconstruction of Hüsamlar coal seam, SW Turkey

NASA Astrophysics Data System (ADS)

Büçkün, Zeynep; İnaner, Hülya; Oskay, Riza Görkem; Christanis, Kimon

2015-06-01

The Ören and Yatağan Basins in SW Turkey host several Miocene coal deposits currently under exploitation for power generation. The present study aims to provide insight into the palaeoenvironmental conditions, which controlled the formation of the Hüsamlar coal seam located in Ören Basin. The coal seam displays many sharp alternations of matrix lignite beds and inorganic, lacustrine sediment layers. The coal is a medium-to-high ash lignite (10.47-31.16 wt%, on dry basis) with high total sulphur content (up to 10 wt%, on dry, ash-free basis), which makes it prone to self-combustion. The maceral composition indicates that the peat-forming vegetation consisted of both arboreal and herbaceous plants, with the latter being predominant in the upper part of the seam. Mica and feldspars contribute to the low part of the seam; carbonates are dominant in the upper part, whereas quartz and pyrite are present along the entire coal profile. The sudden transitions of the telmatic to the lacustrine regime and reverse is attributed to tectonic movements that controlled water table levels in the palaeomire, which affected surface runoff and hence, clastic deposition.

Transitioning Groundwater from an Extractive Resource to a Managed Water Storage Resource: Geology and Recharge in Sedimentary Basins

NASA Astrophysics Data System (ADS)

Maples, S.; Fogg, G. E.; Maxwell, R. M.; Liu, Y.

2017-12-01

Civilizations have typically obtained water from natural and constructed surface-water resources throughout most of human history. Only during the last 50-70 years has a significant quantity of water for humans been obtained through pumping from wells. During this short time, alarming levels of groundwater depletion have been observed worldwide, especially in some semi-arid and arid regions that rely heavily on groundwater pumping from clastic sedimentary basins. In order to reverse the negative effects of over-exploitation of groundwater resources, we must transition from treating groundwater mainly as an extractive resource to one in which recharge and subsurface storage are pursued more aggressively. However, this remains a challenge because unlike surface-water reservoirs which are typically replenished over annual timescales, the complex geologic architecture of clastic sedimentary basins impedes natural groundwater recharge rates resulting in decadal or longer timescales for aquifer replenishment. In parts of California's Central Valley alluvial aquifer system, groundwater pumping has outpaced natural groundwater recharge for decades. Managed aquifer recharge (MAR) has been promoted to offset continued groundwater overdraft, but MAR to the confined aquifer system remains a challenge because multiple laterally-extensive silt and clay aquitards limit recharge rates in most locations. Here, we simulate the dynamics of MAR and identify potential recharge pathways in this system using a novel combination of (1) a high-resolution model of the subsurface geologic heterogeneity and (2) a physically-based model of variably-saturated, three-dimensional water flow. Unlike most groundwater models, which have coarse spatial resolution that obscures the detailed subsurface geologic architecture of these systems, our high-resolution model can pinpoint specific geologic features and locations that have the potential to `short-circuit' aquitards and provide orders-of-magnitude greater recharge rates and volumes than would be possible over the rest of the landscape. Our results highlight the importance of capturing detailed geologic heterogeneity and physical processes that are not typically included in groundwater models when evaluating groundwater recharge potential.

Stratigraphy, U-Th chronology, and paleoenvironments at Gladysvale Cave: insights into the climatic control of South African hominin-bearing cave deposits.

PubMed

Pickering, Robyn; Hancox, Phillip J; Lee-Thorp, Julia A; Grün, Rainer; Mortimer, Graham E; McCulloch, Malcolm; Berger, Lee R

2007-11-01

Gladysvale Cave is one of the few Plio-Pleistocene hominin-bearing cave sites in South Africa that contains a well-stratified cave fill with clastic sediments interspersed with flowstones. The clastic sediments can be divided into units based on the presence of intercalated flowstones, forming flowstone bounded units (FBU). Ten MC-ICP-MS uranium-series dates on several flowstone horizons in the Gladysvale Internal Deposit fan indicate deposition from the late mid-Pleistocene ( approximately 570 ka) to Holocene ( approximately 7 ka) during limited periods of higher effective moisture. Clastic sedimentation occurred during the interceding, presumably more arid, periods. This sequence is not consistent with earlier models for South African caves that simply assumed interglacial sedimentation and glacial erosion. (13)C/(12)C data suggest that flowstone tended to form during periods with higher proportions of C(3) plants in the local vegetation, while clastic sediments reflect higher proportions of C(4) grasses, although this is not always the case. We argue that flowstones are precipitated during periods of higher effective precipitation and restricted cave entrances, while clastic sediments accumulated during periods with more open vegetation. The sedimentary fill of the fossiliferous deposits are, therefore, highly episodic in nature, with large periods of time unlikely to be represented. This has serious implications for the other hominin-bearing caves close by, as these deposits are likely to be similarly episodic. This is especially pertinent when addressing extinction events and reconstructions of paleoenvironments, as large periods of time may be unrecorded. The Gladysvale Cave fill sediments may serve as a climatically forced chronostratigraphic model for these less well-stratified and well-dated Plio-Pleistocene sites.

Probing the mechanism for Deep Submarine Groundwater Discharge using a Case Study in the Levant Basin (Achziv Canyon)

NASA Astrophysics Data System (ADS)

Paldor, A.; Aharonov, E.; Katz, O.

2017-12-01

Deep Submarine Groundwater Discharge (DSGD) is a ubiquitous and highly significant phenomenon, yet it remains poorly understood. Here we use numerical modeling (FEFLOW) to investigate a case study of DSGD offshore northern Israel, aiming to unravel the main features and mechanics of steady-state DSGD: the hydrology that enables its formation, the controls on rates and salinity of seepage, and the residence time of fluid underground. In addition, we investigate the geometry of the fresh-salt water interface within the seeping offshore aquifer. The first part of this work constructs a large scale (70 km) geologic cross-section of our case-study region. The mapping suggests outcropping of confined aquifer strata (Upper Cenomanian Judea Group) on the continental shelf break, 5-15 km offshore. The second part consists of hydrological simulations of DSGD from a confined aquifer similar to the case-study aquifer. The main findings are thus: steady-state DSGD from a confined aquifer occurs far offshore even under moderate heads. It is accompanied by a circulation cell that forms around an intrinsic freshwater-seawater interface. Circulation consists of seawater entering the confined aquifer at the exposed section offshore, mixing with terrestrial groundwater within the aquifer, and seeping saline water out the upper part of the exposed section. In addition, the simulated confined aquifer displays a very flat fresh-salt water interface extending far offshore, as observed in natural offshore aquifers. Preliminary results of a hydrographic survey in the area of study suggest a low-salinity anomaly close to the seafloor, implying seepage of brines in that area, as expected from the model. These new insights have potentially important implications for coastal hydrology, seawater chemistry, biogeochemistry, and submarine slope instability.

Microstructural study of natural fractures in Cape Roberts Project 3 core, Western Ross Sea, Antarctica

USGS Publications Warehouse

Millan, C.; Wilson, T.; Paulsen, T.

2007-01-01

Microstructures in natural fractures in core recovered offshore from Cape Roberts, Ross Sea, Antarctica, provide new constraints on the relative timing of faulting and sedimentation in the Victoria Land Basin along the Transantarctic Mountain rift flank. This study characterizes the textures, fabrics and grain-scale structures from thin section analysis of samples of microfaults, veins, and clastic dikes. Microfaults are abundant and display two different types of textures, interpreted to record two different deformation modes: pre-lithification shearing and brittle faulting of cohesive sediment. Both clastic dikes and calcite veins commonly follow fault planes, indicating that injections of liquefied sediment and circulating fluids used pre-existing faults as conduits. The close association of clastic injections, diagenetic mineralization, and faulting indicates that faulting was synchronous with deposition in the rift basin

The system controlling the composition of clastic sediments

USGS Publications Warehouse

Johnsson, Mark J.

1993-01-01

The composition of clastic sediments and rocks is controlled by a complex suite of parameters operating during pedogenesis, erosion, transport, deposition, and burial. The principal first-order parameters include source rock composition, modification by chemical weathering, mechanical disaggregation and abrasion, authigenic inputs, hydrodynamic sorting, and diagenesis. Each of these first-order parameters is influenced to varying degrees by such factors as the tectonic settings of the source region, transportational system and depositional environment, climate, vegetation, relief, slope, and the nature and energy of transportational and depositional systems. These factors are not independent; rather a complicated web of interrelationships and feedback mechanisms causes many factors to be modulated by others. Accordingly, processes controlling the composition of clastic sediments are best viewed as constituting a system, and in evaluating compositional information the dynamics of the system must be considered as whole.

Sources of groundwater and characteristics of surface-water recharge at Bell, White, and Suwannee Springs, Florida, 2012–13

USGS Publications Warehouse

Stamm, John F.; McBride, W. Scott

2016-12-21

Discharge from springs in Florida is sourced from aquifers, such as the Upper Floridan aquifer, which is overlain by an upper confining unit that locally can have properties of an aquifer. Water levels in aquifers are affected by several factors, such as precipitation, recharge, and groundwater withdrawals, which in turn can affect discharge from springs. Therefore, identifying groundwater sources and recharge characteristics can be important in assessing how these factors might affect flows and water levels in springs and can be informative in broader applications such as groundwater modeling. Recharge characteristics include the residence time of water at the surface, apparent age of recharge, and recharge water temperature.The groundwater sources and recharge characteristics of three springs that discharge from the banks of the Suwannee River in northern Florida were assessed for this study: Bell Springs, White Springs, and Suwannee Springs. Sources of groundwater were also assessed for a 150-foot-deep well finished within the Upper Floridan aquifer, hereafter referred to as the UFA well. Water samples were collected for geochemical analyses in November 2012 and October 2013 from the three springs and the UFA well. Samples were analyzed for a suite of major ions, dissolved gases, and isotopes of sulfur, strontium, oxygen, and hydrogen. Daily means of water level and specific conductance at White Springs were continuously recorded from October 2012 through December 2013 by the Suwannee River Water Management District. Suwannee River stage at White Springs was computed on the basis of stage at a U.S. Geological Survey streamgage about 2.4 miles upstream. Water levels in two wells, located about 2.5 miles northwest and 13 miles southeast of White Springs, were also used in the analyses.Major ion concentrations were used to differentiate water from the springs and Upper Floridan aquifer into three groups: Bell Springs, UFA well, and White and Suwannee Springs. When considered together, evidence from water-level, specific conductance, major-ion concentration, and isotope data indicated that groundwater at Bell Springs and the UFA well was a mixture of surface water and groundwater from the upper confining unit, and that groundwater at White and Suwannee Springs was a mixture of surface water, groundwater from the upper confining unit, and groundwater from the Upper Floridan aquifer. Higher concentrations of magnesium in groundwater samples at the UFA well than in samples at Bell Springs might indicate less mixing with surface water at the UFA well than at Bell Springs. Characteristics of surface-water recharge, such as residence time at the surface, apparent age, and recharge water temperature, were estimated on the basis of isotopic ratios, and dissolved concentrations of gases such as argon, tritium, and sulfur hexafluoride. Oxygen and deuterium isotopic ratios were consistent with rapid recharge by rainwater for samples collected in 2012, and longer residence time at the surface (ponding) for samples collected in 2013. Apparent ages of groundwater samples, computed on the basis of tritium activity and sulfur hexafluoride concentration, indicated groundwater recharge occurred after the late 1980s; however, the estimated apparent ages likely represent the average of ages of multiple sources. Recharge since the 1980s is consistent with groundwater from shallow sources, such as the upper confining unit and Upper Floridan aquifer. Recharge water temperature computed for the three springs and UFA well averaged 20.1 degrees Celsius, which is similar to the mean annual air temperature of 20.6 degrees Celsius at a nearby weather station for 1960–2014.

Magnetotellurics applied to the study of the Guaraní aquifer in Entre Ríos Province, N-E Argentina

NASA Astrophysics Data System (ADS)

Favetto, Alicia; Curcio, Ana; Pomposiello, Cristina

2011-07-01

The South American Guaraní Aquifer System covers the entire Parana basin and part of the Chaco-Parana basin. This system is one of the most important groundwater reservoirs; it is shared by four neighboring countries covering an area larger than one million square kilometers. The geological units closely related to the Guaraní Aquifer are the Piramboia and Botucatu Formations that consist of Triassic-Jurassic aeolian, fluvial and lacustrine sandstones, and the Serra Geral basalts with clastic intercalations. Serra Geral, an effusive Cretaceous complex, covers the sandstones and provides a high degree of confinement to the system. This paper presents the interpretation of magnetotelluric (MT) data collected during 2007-2008 in Entre Ríos Province, Argentina. These data, recorded in three profiles, mainly provide the depth to the crystalline basement, determinant for the presence of aquifer-related sediments. Models showed that the discrimination of the basalts strongly depends on local electrical characteristics. Model information is quite consistent with the information from oil and thermal wells located close to the profiles.

Hydrothermal mineralization along submarine rift zones, Hawaii

USGS Publications Warehouse

Hein, J.R.; Gibbs, A.E.; Clague, D.A.; Torresan, M.

1996-01-01

Describes mineralization of midplate submarine rift zones and hydrothermal manganese oxide mineralization of midplate volcanic edifices. Hydrothermal Mn oxides were recovered from submarine extensions of two Hawaiian rift zones, along Haleakala and Puna Ridges. These Mn oxides form two types of deposits, metallic stratiform layers in volcaniclastic rocks and cement for clastic rocks; both deposit types are composed of todorokite and birnessite. Unlike most other hydrothermal Mn oxide deposits, those from Hawaiian rift zones are enriched in the trace metals Zn, Co, Ba, Mo, Sr, V, and especially Ni. Metals are derived from three sources: mafic and ultramafic rocks leached by circulating hydrothermal fluids, clastic material (in Mn-cemented sandstone), and seawater that mixed with the hydrothermal fluids. Precipitation of Mn oxide below the seafloor is indicated by its occurrence as cement, growth textures that show mineralizing fluids were introduced from below, and pervasive replacement of original matrix of clastic rocks.Hydrothermal Mn oxides were recovered from submarine extensions of two Hawaiian rift zones, along Haleakala and Puna Ridges. These Mn oxides form two types of deposits, metallic stratiform layers in volcaniclastic rocks and cement for clastic rocks. Both deposit types are composed of todorokite and birnessite. This article describes in detail the specific characteristics of these Mn oxides.

Hydrogeology and chemical quality of water and soil at Carroll Island, Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Tenbus, F.J.; Phillips, S.W.

1996-01-01

Carroll Island was used for open-air testing of chemical warfare agents from the late 1940's until 1971. Testing and disposal activities weresuspected of causing environmental contamination at 16 sites on the island. The hydrogeology and chemical quality of ground water, surface water, and soil at these sites were investigated with borehole logs, environmental samples, water-level measurements, and hydrologic tests. A surficial aquifer, upper confining unit, and upper confined aquifer were defined. Ground water in the surficial aquifer generally flows from the east-central part of the island toward the surface-water bodies, butgradient reversals caused by evapotranspiration can occur during dry seasons. In the confined aquifer, hydraulic gradients are low, and hydraulic head is affected by tidal loading and by seasonal pumpage from the west. Inorganic chemistry in the aquifers is affected by brackish-water intrusion from gradient reversals and by dissolution ofcarboniferous shell material in the confining unit.The concentrations of most inorganic constituents probably resulted from natural processes, but some concentrations exceeded Federal water-quality regulations and criteria. Organic compounds were detected in water and soil samples at maximum concentrations of 138 micrograms per liter (thiodiglycol in surface water) and 12 micrograms per gram (octadecanoic acid in soil).Concentrations of organic compounds in ground water exceeded Federal drinking-water regulations at two sites. The organic compounds that weredetected in environmental samples were variously attributed to natural processes, laboratory or field- sampling contamination, fallout from industrial air pollution, and historical military activities.

Nuclear reactor

DOEpatents

Yant, Howard W.; Stinebiser, Karl W.; Anzur, Gregory C.

1977-01-01

A nuclear reactor, particularly a liquid-metal breeder reactor, whose upper internals include outlet modules for channeling the liquid-metal coolant from selected areas of the outlet of the core vertically to the outlet plenum. The modules are composed of a highly-refractory, high corrosion-resistant alloy, for example, INCONEL-718. Each module is disposed to confine and channel generally vertically the coolant emitted from a subplurality of core-component assemblies. Each module has a grid with openings, each opening disposed to receive the coolant from an assembly of the subplurality. The grid in addition serves as a holdown for the assemblies of the corresponding subplurality preventing their excessive ejection upwardly from the core. In the region directly over the core the outlet modules are of such peripheral form that they nest forming a continuum over the core-component assemblies whose outlet coolant they confine. Each subassembly includes a chimney which confines the coolant emitted by its corresponding subassemblies to generally vertical flow between the outlet of the core and the outlet plenum. Each subplurality of assemblies whose emitted coolant is confined by an outlet module includes assemblies which emit lower-temperature coolant, for example, a control-rod assembly, or fertile assemblies, and assemblies which emit coolant of substantially higher temperature, for example, fuel-rod assemblies. The coolants of different temperatures are mixed in the chimneys reducing the effect of stripping (hot-cold temperature fluctuations) on the remainder of the upper internals which are composed typically of AISI-304 or AISI-316 stainless steel.

Well sealing via thermite reactions

DOEpatents

Lowry, William Edward; Dunn, Sandra Dalvit

2016-11-15

A platform is formed in a well below a target plug zone by lowering a thermite reaction charge into the well and igniting it, whereby the products of the reaction are allowed to cool and expand to form a platform or support in the well. A main thermite reaction charge is placed above the platform and ignited to form a main sealing plug for the well. In some embodiments an upper plug is formed by igniting an upper thermite reaction charge above the main thermite reaction charge. The upper plug confines the products of ignition of the main thermite reaction charge.

Potentiometric surface of the upper Floridan aquifer, west-central Florida, May 2011

USGS Publications Warehouse

Ortiz, Anita G.

2011-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2011. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when groundwater levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 45.74 inches for west-central Florida (from June 2010 through May 2011) was 6.85 inches below the historical cumulative average of 52.59 inches (Southwest Florida Water Management District, 2011). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September from 1975 through 2010. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 23-27, 2011. Supplemental water-level data were collected by other agencies and companies. Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a "snapshot" of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition.

Potentiometric Surface of the Upper Floridan Aquifer, West-central Florida, May 2010

USGS Publications Warehouse

Ortiz, A.G.

2010-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2010. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when groundwater levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 55.21 inches for west-central Florida (from June 2009 through May 2010) was 2.55 inches above the historical cumulative average of 52.66 inches (Southwest Florida Water Management District, 2010). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 17-21, 2010. Supplemental water-level data were collected by other agencies and companies. Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition.

Hydrogeology and simulation of ground-water flow at US Marine Corps Air Station, Cherry Point, North Carolina, 1987-90

USGS Publications Warehouse

Eimers, J.L.; Daniel, C. C.; Coble, R.W.

1994-01-01

Geophysical and lithologic well-log data from 30 wells and chloride data, and water-level data from oil-test wells, supply wells, and observation wells were evaluated to define the hydrogeologic framework at the U.S. Marine Corps Air Station, Cherry Point, North Carolina. Elements of the hydrogeologic framework important to this study include six aquifers and their respective confining units. In descending order, these aquifers are the surficial, Yorktown, Pungo River, upper and lower Castle Hayne, and Beaufort. The upper and lower Castle Hayne and Beaufort aquifers and related confining units are relatively continuous throughout the study area. The surficial, Yorktown, Pungo River, and upper and lower Castle Hayne aquifers contain freshwater. The upper and lower Castle Hayne aquifers serve as the Air Station?s principal supply of freshwater. However, the lower Castle Hayne aquifer contains brackish water near its base and there is potential for upward movement of this water to supply wells completed in this aquifer. The potential for brackish-water encroachment is greatest if wells are screened too deep in the lower Castle Hayne aquifer or if pumping rates are too high. Lateral movement of brackish water into aquifers incised by estuarine streams is also possible if ground-water flow gradients toward these bodies are reversed by pumping. The potential for the reversed movement of water from the surficial aquifer downward to the water-supply aquifer is greatest in areas where clay confining units are missing. These missing clay units could indicate the presence of a paleochannel of the Neuse River. A quasi three-dimensional finite-difference ground-water flow model was constructed and calibrated to simulate conditions at and in the vicinity of the Air Station for the period of 1987-90. Comparisons of 94 observed and computed heads were made, and the average difference between them is -0.2 feet with a root mean square error of 5.7 feet. An analysis was made to evaluate the sensitivity of the model to the absence of the Yorktown and Pungo River confining units in a 1-square-mile area in the southern part of the Air Station. This analysis resulted in a maximum simulated head increase of 2 feet in one 0.11-square-mile model cell in the Pungo River aquifer.

Sedimentation, zoning of reservoir rocks in W. Siberian basin oil fields

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

Kliger, J.A.

1994-02-07

A line pattern of well cluster spacing was chosen in western Siberia because of taiga, marshes, etc., on the surface. The zoning of the oil pools within productive Upper Jurassic J[sub 3] intervals is complicated. This is why until the early 1990s almost each third well drilled in the Shaimsky region on the western edge of the West Siberian basin came up dry. The results of development drilling would be much better if one used some sedimentological relationships of zoning of the reservoir rocks within the oil fields. These natural phenomena are: Paleobasin bathymetry; Distances from the sources of themore » clastic material; and Proximity of the area of deposition. Using the diagram in this article, one can avoid drilling toward areas where the sandstone pinch out, area of argillization of sand-stones, or where the probability of their absence is high.« less

Suggested nomenclature change and new reference locality for Dequeen Formation, Pike County, Arkansas

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

Ham, T.L.; Landry, R.J.

1983-09-01

The DeQueen Formation of the Trinity Group, Comanchean Cretaceous, crops out in southwestern Arkansas and southeastern Oklahoma. The outcrop, located in the Highland gypsum quarry of Pike County, southwestern Arkansas, is described in detail in this paper and presented as a reference locality. Data from the locality provide the basis for a nomenclature change from the DeQueen Limestone Member to the DeQueen Formation. The formation consists of 64.23% clastic sediments, 24.72% gypsum, and 11.05% limestone. Hopper salt casts, ripple marks, scattered pyrite and marcasite nodules, celestite, and chickenwire gypsum can also be found. The DeQueen Formation is underlain by claysmore » and the Ultima Thule Gravel lentil, while the top is unconformably overlain by Upper Cretaceous Tokio gravels. The general paleoenvironment represents a normally low-energy subtidal environment ranging from brackish to normal to hypersaline waters in a lagoonal setting that shallows upward.« less

The interplay between subduction and lateral extrusion: A case study for the European Eastern Alps based on analogue models

NASA Astrophysics Data System (ADS)

van Gelder, I. E.; Willingshofer, E.; Sokoutis, D.; Cloetingh, S. A. P. L.

2017-08-01

A series of analogue experiments simulating intra-continental subduction contemporaneous with lateral extrusion of the upper plate are performed to study the interference between these two processes at crustal levels and in the lithospheric mantle. The models demonstrate that intra-continental subduction and coeval lateral extrusion of the upper plate are compatible processes leading to similar deformation structures within the extruding region as compared to the classical setup, lithosphere-scale indentation. Strong coupling across the subduction boundary allows for the transfer of stresses to the upper plate, where strain regimes are characterized by crustal thickening near a confined margin and dominated by lateral displacement of material near a weak lateral confinement. The strain regimes propagate laterally during ongoing convergence creating an area of overlap characterized by transpression. When subduction is oblique to the convergence direction, the upper plate is less deformed and as a consequence the amount of lateral extrusion decreases. In addition, strain is partitioned along the oblique plate boundary resulting in less subduction in expense of right lateral displacement close to the weak lateral confinement. Both oblique and orthogonal subduction models have a strong resemblance to lateral extrusion tectonics of the Eastern Alps (Europe), where subduction of the adjacent Adriatic plate beneath the Eastern Alps is debated. Our results imply that subduction of Adria is a valid mechanisms to induce extrusion-type deformation within the Eastern Alps lithosphere. Furthermore, our findings suggest that the Oligocene to Late Miocene structural evolution of the Eastern Alps reflects a phase of oblique subduction followed by a later stage of orthogonal subduction conform a Miocene shift in the plate motion of Adria. Oblique subduction also provides a viable mechanism to explain the rapid decrease in slab length of the Adriatic plate beneath the Eastern Alps towards the Pannonian Basin.

Stratigraphy, petrography, and provenance of Archean sedimentary rocks of the Nsuze Group, Pongola Supergroup, in the Wit M'folozi Inlier, South Africa

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

Gamero de Villarroel, H.; Lowe, D.R.

1993-02-01

The Upper Archean Pongola Supergroup is a succession of clastic and volcanic rocks that represents the oldest relatively unmetamorphosed sedimentary sequence deposited on the basement of the 3.5-3.2 Ga-old Kaapvaal Craton. The Pongola Supergroup includes two subdivisions, the Nsuze and the Mozaan Groups. The Nsuze Group is composed of clastic rocks, minor carbonate units, and basalt. Nsuze sandstones are dominated by granite-derived sediments, and minor basaltic-derived detritus. Most Nsuze sedimentary rocks are sandstones that include both quartz-fieldspar and lithic-rich varieties. The mineralogy of Nsuze sandstones reflects the mixing of debris derived from two distinctive sources: (1) a sialic plutonic sourcemore » yielding quartz and microcline and (2) a basaltic source yielding basaltic lithic detritus and plagioclase. The most likely source rocks for the Nsuze sandstones in the Wit M'folozi Inlier were Archean granitic basement, represented by the Mpuluzi batholith, and Nsuze basaltic volcanic rocks. Both continental arc and rift settings have been proposed for the Pongola Supergroup. Nsuze sandstones show similarities to continental arc sandstone suites. However, there is no report of the existence of high standing stratovolcanoes, calc-alkaline plutonism, or contact and regional metamorphism of the intruded volcanic-sedimentary and basement rocks in the Pongola basin, features that are typically associated with continental arcs. The dominance of continent-derived detritus in the Nsuze Group argues that volcanic rocks made up a minor part of the exposed source area and that volcanism was largely restricted to the basin of deposition. Collectively, available evidence favors an intracratonic rift for the depositional setting of the Nsuze Group.« less

Recent sediments of the St. Marks River coast, northwest Florida, a low-energy, sediment-starved estuary

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

Highly, A.B.; Donoghue, J.F.; Garrett, C.

1994-03-01

The St. Marks river of northwest Florida drains parts of the central panhandle of northwestern Florida, and a small area in southwestern Georgia. It traverses nearly 56.3 kilometers through a watershed of 1,711 square kilometers. The slow-moving river carries little sediment and terminates in Apalachee Bay, a low-energy embayment in the northeasternmost Gulf of Mexico. The coastal region is characterized by mudflats, seagrass beds, and an absence of sandy beaches and barrier islands. Clastic sediments of the coast and shelf rest on a shallow-dipping carbonate platform. The upper surface of the platform is locally karstic. As a result, like othermore » rivers in this region of northwest Florida, the St. Marks watershed is marked by sinkholes and disappearing streams. The fact that the river travels underground through part of its lower watershed serves to trap or sieve some of its clastic load. In the estuary, the undulating karst topography causes the estuarine sediments to vary in thickness from 0 to 4+ meters. The concave shape of the coastline and its orientation with respect to prevailing winds result in low average wave energy. Sedimentation is therefore controlled by riverine and tidal forces. The relatively low energy conditions result in good preservation of the sedimentary record in the St. Marks estuary. A suite of sediment cores has been collected in the lower river, estuary and adjacent Gulf of Mexico. Lead-210 dating results indicate a slow average sedimentation rate ([approximately] 1mm/yr). Investigation of sedimentation rates and sediment characteristics over time in the St. Marks estuary indicate that sedimentologic conditions in this low-energy environment have been relatively stable during the recent geologic history of the estuary.« less

The Sredne-Amursky basin: A migrating cretaceous depocenter for the Amur river, eastern Siberia

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

Light, M.; Maslanyj, M.; Davidson, K.

1993-09-01

Recently acquired seismic, well, and regional geological data imply favorable conditions for the accumulation of oil and gas in the 20,000 km[sup 2] Sredne-Amursky basin. Major graben and northeast-trending sinistral wrench-fault systems are recognized in the basin. Lower and Upper Cretaceous sediments are up to 9000 and 3000 m thick, respectively. Paleogeographic reconstructions imply that during the Late Triassic-Early Cretaceous the Sredne-Amursky basin was part of a narrow marine embayment (back-arc basin), which was open to the north. During the Cretaceous, the region was part of a foreland basin complicated by strike-slip, which produced subsidence related to transtension during obliquemore » collision of the Sikhote-Alin arc with Eurasian margin. Contemporaneous uplift also related to this collision migrated from south to north and may have sourced northward-directed deltas and alluvial fans, which fed northward into the closing back-arc basin between 130 and 85 Ma. The progradational clastic succession of the Berriasian-Albian and the Late Cretaceous fluvial, brackish water and paralic sediments within the basin may be analogous to the highly productive late Tertiary clastics of the Amur River delta in the northeast Sakhalin basin. Cretaceous-Tertiary lacustrine-deltaic sapropelic shales provide significant source and seal potential and potential reservoirs occur in the Cretaceous and Tertiary. Structural plays were developed during Cretaceous rifting and subsequent strike-slip deformation. If the full hydrocarbon potential of the Sredne-Amursky basin is to be realized, the regional appraisal suggests that exploration should be focused toward the identification of plays related to prograding Cretaceous deltaic depositional systems.« less

Changing Depositional Conditions of the Cretaceous-Paleocene Sediments in the Southern Sakarya Zone and Implications for Tectonic Evolution

NASA Astrophysics Data System (ADS)

Baykut, Tanyel; Koral, Hayrettin; Özkar Öngen, İzver

2016-04-01

Study area is located between Göynük (Bolu) and Nallıhan (Ankara), NW Anatolia, to the north of the Neotethyan (Izmir-Ankara-Erzincan) Suture Zone. It comprises units ranging from the Jurassic to Miocene ages. Middle Jurassic-Lower Cretaceous age pelagic limestones of the Soǧukçam Formation is the oldest rock, overlain by the Upper Cretaceous Gölpazarı Group. The Gölpazarı Group includes the Cenomanian-Campanian age turbiditic Yenipazar Formation and the Maastrichtian age Taraklı Formation. Over the Taraklı Formation lies conformably the Kızılçay Group, and it exhibits varying facies from north to south of the study area. In the north, there occurs the coral-bearing Lower Paleocene Selvipınar Formation. In the south, instead, there are clastics of the Kızılçay Group overthrust by the Soǧukçam Formation. Clastics and bituminous shales of the Kızılçay Group indicate a terrestrial setting of the study area during the Lower Paleocene-Eocene. The Soǧukçam and Yenipazar Formations represent deep marine conditions, while the Taraklı Formation a shallow one. This indicates the region underwent a rapid uplift due possibly to initial collision and overthrusting. In the post-Maastrichtian age units, the occurrence and lateral transitions of shallow marine and terrestrial sediments suggest a progress of uplift, but at different rates at different locations; at a relatively fast rate in the south and a slow rate in the north. The presence of tectonic features such as E-W oriented folds, overturned folds and faults are related to shortening during a collisional stage that affected the whole region.

Well characteristics influencing arsenic concentrations in ground water.

PubMed

Erickson, Melinda L; Barnes, Randal J

2005-10-01

Naturally occurring arsenic contamination is common in ground water in the upper Midwest. Arsenic is most likely to be present in glacial drift and shallow bedrock wells that lie within the footprint of northwest provenance Late Wisconsinan glacial drift. Elevated arsenic is more common in domestic wells and in monitoring wells than it is in public water system wells. Arsenic contamination is also more prevalent in domestic wells with short screens set in proximity to an upper confining unit, such as glacial till. Public water system wells have distinctly different well-construction practices and well characteristics when compared to domestic and monitoring wells. Construction practices such as exploiting a thick, coarse aquifer and installing a long well screen yield good water quantity for public water system wells. Coincidentally, these construction practices also often yield low arsenic water. Coarse aquifer materials have less surface area for adsorbing arsenic, and thus less arsenic available for potential mobilization. Wells with long screens set at a distance from an upper confining unit are at lower risk of exposure to geochemical conditions conducive to arsenic mobilization via reductive mechanisms such as reductive dissolution of metal hydroxides and reductive desorption of arsenic.

Ground-water recharge and flowpaths near the edge of the Decorah-Platteville-Glenwood confining unit, Rochester, Minnesota

USGS Publications Warehouse

Lindgren, Richard J.

2001-01-01

The water withdrawn by pumped wells or discharged to Bear Creek is derived predominantly from areal recharge near the edge of the Decorah-Platteville-Glenwood confining unit (0.47 ft3/s), rather than from water that has leaked downward through the Decorah unit (0.03 ft3/s). Model simulated discharge through springs and seeps in the lower part of the upper carbonate aquifer (0.21 ft3/s) represents a potential source of water to the St. Peter-Prairie du Chien-Jordan aquifer.

Sedimentological imprints of environmental variability at the Balkan Peninsula on the sediment sequence of Lake Ohrid (Macedonia, Albania) between the Mid Pleistocene Transition and present days: The ICDP SCOPSCO project

NASA Astrophysics Data System (ADS)

Francke, Alexander; Wagner, Bernd; Leicher, Niklas; Raphael, Gromig; Leng, Melanie; Lacey, Jack; Vogel, Hendrik; Baumgarten, Henrike; Thomas, Wonik; Zanchetta, Giovanni; Roberto, Sulpizio; Krastel, Sebastian; Lindhorst, Katja

2015-04-01

The UNESCO World Heritage site of Lake Ohrid in the Balkans is thought to be the oldest, continuously existing lake in Europe. In order to unravel the geological and evolutionary history of the lake, a deep drilling campaign was conducted in spring 2013 under the umbrella of the ICDP SCOPSCO project. At the coring site "DEEP" in central parts of the lake, more than 1,500 m of sediments were recovered down to a penetration depth of 569 m blf. This sediment sequence is assumed to be more than 1.2 Ma old and likely covers the entire lacustrine deposits of the Lake Ohrid Basin. Currently, an age model for the upper 260m of the DEEP- site sequence is available. This age model is based on chronological tie points (tephrochronology), and wiggle matching of down hole logging data and (bio-)geochemistry data (XRF, TIC, TOC) from the core sequence to the global benthic stack LR04 and local insolation patterns. The data suggests that the upper 260 m of the DEEP-site sequence corresponds to the time period between the Mid Pleistocene Transition (MPT) and present days. During this period, the sedimentological properties of the sediments show a strong dependency on environmental variability in the area. Interglacial deposits appear massive or marbled, contain up to 80 % of CaCO3 (high TIC), high amounts of organic matter (high TOC) and biogenic silica (high BSi), and low contents of clastic material. Glacial deposits are predominantly marbled and calcite is generally absent. Similarly, the amounts of organic matter and biogenic silica are low, and glacial sediments predominately consist of clastic matter. Distinct layers of siderite and uniformly distributed Fe- or Mn- oxides occur in the glacial deposits, vivianite concretions occur in both the glacial and interglacial periods. High CaCO3 contents in deposits formed during warm (interglacial) periods are also known from studies on short pilot cores from Lake Ohrid and are triggered by increased productivity in the lake, such as also indicated by enhanced contents of organic matter and biogenic silica. Thereby, CaCO3 precipitation is caused by photosynthesis induced calcite precipitation during algae blooms in spring and early summer. Negligible contents of TIC in deposits formed during glacial periods can be explained by an overall low productivity (low TOC and BSi) and, in addition, by dilution of CaCO3. Dilution of CaCO3 might be a result of more acid bottom water conditions, triggered by improved mixing conditions (less thermal stratification), oxidation of OM and CO2 release from the surface sediments. Oxygenated surface sediments and degradation of organic matter are indicated by the marbled structure of the glacial sediments implying intensive bioturbation, and by TOC/TN ratios around 4, respectively. The high amount of clastic material in deposits from cold (glacial) periods can be a result of mutual dilution with calcite, organic matter and biogenic silica, but might also indicate more intensive erosion in the catchment due to a less dense vegetation cover.

Tracking an upper limit of the "Carnian Crisis" and/or Carnian stage in the Western Carpathians (Slovakia)

NASA Astrophysics Data System (ADS)

Kohút, Milan; Hofmann, Mandy; Havrila, Milan; Linnemann, Ulf; Havrila, Jakub

2018-01-01

The Late Triassic timescale, especially the Carnian-Norian boundary, is poorly constrained mainly due to a paucity of high-precision radio-isotopic ages that can be related accurately to contradictions between the biostratigraphic and magnetostratigraphic correlations. LA ICP-MS dating of detrital zircons from five samples of the Lunz Formation—the Upper Triassic siliciclastic sediments from the Western Carpathians (Slovakia)—provided a wide spectrum of ages that vary from Late Archaean (ca. 2582 Ma) to Triassic (ca. 216 Ma). These marine delta sediments represent a typical product of the "Carnian Crisis"—a major climate change and biotic turnover that occurred during the Carnian stage in the Tethys Ocean within the carbonate shelf and intrashelf basins in the Northern Calcareous Alps and the Western Carpathians. The supply of clastic material in the studied Lunz Formation was derived from several sources, especially: (i) from the recycled Variscan orogen; (ii) from the remote East European Platform; and (iii) from the contemporaneous Triassic volcanic sources. Syn-sedimentary volcanic zircons with a concordia age of 221.2 ± 1.6 Ma (calculated from 12 single analyses) represent the maximum age of deposition of the Lunz Formation, and demonstrate that the upper limit of the "Carnian Crisis" and/or the Carnian stage in the Alpine-Carpathians realm is younger than the current age of the Carnian-Norian boundary at ca. 227 Ma listed on the International Chronostratigraphic Chart (International Commission on Stratigraphy 2016/12 Edition).

Tectonic control on sediment sources in the Jaca basin (Middle and Upper Eocene of the South-Central Pyrenees)

NASA Astrophysics Data System (ADS)

Roigé, Marta; Gómez-Gras, David; Remacha, Eduard; Daza, Raquel; Boya, Salvador

2016-03-01

The Eocene clastic systems of the Jaca foreland Basin (southern Pyrenees) allow us to identify changes in sediment composition through time. We provide new data on sediment composition and sources of the northern Jaca basin, whose stratigraphic evolution from Middle Lutetian deep-marine to Priabonian alluvial systems record a main reorganization in the active Pyrenean prowedge. Petrological analysis shows that the Banastón and the Lower Jaca turbidite systems (Middle-Upper Lutetian) were fed from an eastern source, which dominated during the sedimentation of the Hecho Group turbidites. In contrast, the upper part of the Jaca turbidite systems (Lutetian-Bartonian transition) records an increase in the number of subvolcanic rock and hybrid-sandstone fragments (intrabasinal and extrabasinal grains) being the first system clearly fed from the north. This change is interpreted as associated with an uplifting of the Eaux-Chaudes/Lakora thrust sheet in the northern Axial Zone. The Middle Bartonian Sabiñánigo sandstone derives from eastern and northeastern source areas. In contrast, the overlying Late Bartonian-Early Priabonian Atarés delta records sediment input from the east. The Santa Orosia alluvial system records a new distinct compositional change, with a very high content of hybrid-sandstone clasts from the Hecho Group, again from a northern provenance. Such cannibalized clasts were sourced from newly emerged areas of the hinterland, associated with the basement-involved Gavarnie thrust activity in the Axial Zone.

Hydrocarbon source rock potential of the Karoo in Zimbabwe

NASA Astrophysics Data System (ADS)

Hiller, K.; Shoko, U.

1996-07-01

The hydrocarbon potential of Zimbabwe is tied to the Karoo rifts which fringe the Zimbabwe Craton, i.e. the Mid-Zambezi basin/rift and the Mana Pools basin in the northwest, the Cabora Bassa basin in the north and the Tuli-Bubye and Sabi-Runde basins in the south. Based on the geochemical investigation of almost one thousand samples of fine clastic Karoo sediments, a concise source rock inventory has been established showing the following features. No marine source rocks have been identified. In the Mid-Zambezi area and Cabora Bassa basin, the source rocks are gas-prone, carbonaceous to coaly mudstones and coal of Lower Karoo age. In the Cabora Bassa basin, similar gas-prone source rocks occur in the Upper Karoo (Angwa Alternations Member). These kerogen type III source rocks are widespread and predominantly immature to moderately mature. In the southern basins, the Lower Karoo source rocks are gas-prone; in addition some have a small condensate potential. Most of the samples are, however, overmature due to numerous dolerite intrusions. Samples with a mixed gas, condensate and oil potential (mainly kerogen types II and III) were identified in the Lower Karoo (Coal Measure and Lower Madumabisa Mudstone Formations) of the Mid-Zambezi basin, and in the Louver Karoo (Mkanga Formation) and Upper Karoo (Upper Angwa Alternations Member Formation) of the Cabora Bassa basin. The source rocks, with a liquid potential, are also immature to moderately mature and were deposited in swamp, paludal and lacustrine environments of limited extent.

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

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

Abreu, V.S.

1996-01-01

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

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

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

Abreu, V.S.

1996-12-31

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

Provenance and sequence architecture of the Middle-Late Eocene Gehannam and Birket Qarun formations at Wadi Al Hitan, Fayum Province, Egypt

NASA Astrophysics Data System (ADS)

Anan, Tarek; El Shahat, Adam

2014-12-01

The Middle-Upper Eocene Gehannam and Birket Qarun formations at Wadi Al Hitan (Valley of Whales) in Fayum Province of Egypt are dominated by marine siliciclastic sediments. Sedimentation took place in synclinal basins that were inherited from the Late Cretaceous tectonism. The siliciclastic sediments accumulated in low energy open shallow marine shelf. Most of the siliciclastics are heavily bioturbated by Thalassinoides. The abundance of unstable and moderately stable heavy minerals suggests that the Middle-Upper Eocene clastics were largely derived from the weathered regolith of the exhumed basement rocks of the Red Sea mountains. The ultrastable heavies were mainly recycled from positive landmass that bound the Eocene basins. Two sequence boundaries were observed in the studied succession. The first boundary lies within a rhizolith bearing-sandstone unit that occurs at the boundary between the Gehannam and Birket Qarun formations. The second sequence boundary occurs within the upper part of the Birket Qarun Formation, in a shale horizon bioturbated by Thalassinoides. Three 3rd order depositional sequences were recognized. These sequences may be formed due to tectonic activity that started in the Late Cretaceous and may be rejuvenated again during the Eocene time. Also emergence activities that were active during the Eocene led to the formation of the picked sequences by changing relative sea level. The recorded systems tracts are transgressive systems tract (TST), highstand systems tract (HST), and falling-stage systems tract (FSST).

Documentation of a computer program to simulate transient leakage from confining units using the modular finite-difference, ground-water flow model

USGS Publications Warehouse

Leake, S.A.; Leahy, P.P.; Navoy, A.S.

1994-01-01

Transient leakage into or out of a compressible fine-grained confining unit results from ground- water storage changes within the unit. The computer program described in this report provides a new method of simulating transient leakage using the U.S. Geological Survey modular finite- difference ground-water flow model (MODFLOW). The new program is referred to as the Transient- Leakage Package. The Transient-Leakage Package solves integrodifferential equations that describe flow across the upper and lower boundaries of confining units. For each confining unit, vertical hydraulic conductivity, thickness, and specific storage are specified in input arrays. These properties can vary from cell to cell and the confining unit need not be present at all locations in the grid; however, the confining units must be bounded above and below by model layers in which head is calculated or specified. The package was used in an example problem to simulate drawdown around a pumping well in a system with two aquifers separated by a confining unit. For drawdown values in excess of 1 centimeter, the solution using the new package closely matched an exact analytical solution. The problem also was simulated without the new package by using a separate model layer to represent the confining unit. That simulation was refined by using two model layers to represent the confining unit. The simulation using the Transient-Leakage Package was faster and more accurate than either of the simulations using model layers to represent the confining unit.

Clastic polygonal networks around Lyot crater, Mars: Possible formation mechanisms from morphometric analysis

NASA Astrophysics Data System (ADS)

Brooker, L. M.; Balme, M. R.; Conway, S. J.; Hagermann, A.; Barrett, A. M.; Collins, G. S.; Soare, R. J.

2018-03-01

Polygonal networks of patterned ground are a common feature in cold-climate environments. They can form through the thermal contraction of ice-cemented sediment (i.e. formed from fractures), or the freezing and thawing of ground ice (i.e. formed by patterns of clasts, or ground deformation). The characteristics of these landforms provide information about environmental conditions. Analogous polygonal forms have been observed on Mars leading to inferences about environmental conditions. We have identified clastic polygonal features located around Lyot crater, Mars (50°N, 30°E). These polygons are unusually large (>100 m diameter) compared to terrestrial clastic polygons, and contain very large clasts, some of which are up to 15 metres in diameter. The polygons are distributed in a wide arc around the eastern side of Lyot crater, at a consistent distance from the crater rim. Using high-resolution imaging data, we digitised these features to extract morphological information. These data are compared to existing terrestrial and Martian polygon data to look for similarities and differences and to inform hypotheses concerning possible formation mechanisms. Our results show the clastic polygons do not have any morphometric features that indicate they are similar to terrestrial sorted, clastic polygons formed by freeze-thaw processes. They are too large, do not show the expected variation in form with slope, and have clasts that do not scale in size with polygon diameter. However, the clastic networks are similar in network morphology to thermal contraction cracks, and there is a potential direct Martian analogue in a sub-type of thermal contraction polygons located in Utopia Planitia. Based upon our observations, we reject the hypothesis that polygons located around Lyot formed as freeze-thaw polygons and instead an alternative mechanism is put forward: they result from the infilling of earlier thermal contraction cracks by wind-blown material, which then became compressed and/or cemented resulting in a resistant fill. Erosion then leads to preservation of these polygons in positive relief, while later weathering results in the fracturing of the fill material to form angular clasts. These results suggest that there was an extensive area of ice-rich terrain, the extent of which is linked to ejecta from Lyot crater.

Implementation and thickness optimization of perpetual pavements in Ohio : [executive summary].

DOT National Transportation Integrated Search

2015-06-01

Perpetual asphalt pavements are designed to confine distresses to the upper layer of the structure, by eliminating : or reducing the potential for fatigue cracking by maintaining the horizontal strains at the bottom of the pavement : below a critical...

Deep Resistivity Structure of Mid Valley, Nevada Test Site, Nevada

USGS Publications Warehouse

Wallin, Erin L.; Rodriguez, Brian D.; Williams, Jackie M.

2009-01-01

The U.S. Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) at their Nevada Site Office (NSO) are addressing ground-water contamination resulting from historical underground nuclear testing through the Environmental Management (EM) program and, in particular, the Underground Test Area (UGTA) project. From 1951 to 1992, 828 underground nuclear tests were conducted at the Nevada Test Site northwest of Las Vegas (DOE UGTA, 2003). Most of these tests were conducted hundreds of feet above the ground-water table; however, more than 200 of the tests were near, or within, the water table. This underground testing was limited to specific areas of the Nevada Test Site including Pahute Mesa, Rainier Mesa/Shoshone Mountain (RM-SM), Frenchman Flat, and Yucca Flat. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow in the area subsequent to a nuclear test. Ground-water modelers would like to know more about the hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Rainier Mesa/Shoshone Mountain (RM-SM) Corrective Action Unit (CAU) (National Security Technologies, 2007). During 2003, the U.S. Geological Survey (USGS), in cooperation with the DOE and NNSA-NSO collected and processed data at the Nevada Test Site in and near Yucca Flat (YF) to help define the character, thickness, and lateral extent of the pre-Tertiary confining units. We collected 51 magnetotelluric (MT) and audio-magnetotelluric (AMT) stations for that research (Williams and others, 2005a, 2005b, 2005c, 2005d, 2005e, and 2005f). In early 2005 we extended that research with 26 additional MT data stations (Williams and others, 2006) located on and near Rainier Mesa and Shoshone Mountain (RM-SM). The new stations extended the area of the hydrogeologic study previously conducted in Yucca Flat, further refining what is known about the pre-Tertiary confining units. In particular, a major goal was to define the extent of the upper clastic confining unit (UCCU). The UCCU is composed of late Devonian to Mississippian siliciclastic rocks assigned to the Eleana Formation and Chainman Shale (National Security Technologies, 2007). The UCCU underlies the Yucca Flat area and extends southwestward toward Shoshone Mountain, westward toward Buckboard Mesa, and northwestward toward Rainier Mesa. Late in 2005 we collected data at an additional 14 MT stations in Mid Valley, CP Hills, and northern Yucca Flat. That work was done to better determine the extent and thickness of the UCCU near the boundary between the southeastern RM-SM CAU and the southwestern YF CAU, and also in the northern YF CAU. The MT data have been released in a separate U.S. Geological Survey report (Williams and others, 2007). The Nevada Test Site magnetotelluric data interpretation presented in this report includes the results of detailed two-dimensional (2-D) resistivity modeling for each profile and inferences on the three-dimensional (3-D) character of the geology within the region.

Abnormal high surface heat flow caused by the Emeishan mantle plume

NASA Astrophysics Data System (ADS)

Jiang, Qiang; Qiu, Nansheng; Zhu, Chuanqing

2016-04-01

It is commonly believed that increase of heat flow caused by a mantle plume is small and transient. Seafloor heat flow data near the Hawaiian hotspot and the Iceland are comparable to that for oceanic lithosphere elsewhere. Numerical modeling of the thermal effect of the Parana large igneous province shows that the added heat flow at the surface caused by the magmatic underplating is less than 5mW/m2. However, the thermal effect of Emeishan mantle plume (EMP) may cause the surface hear-flow abnormally high. The Middle-Late Emeishan mantle plume is located in the western Yangtze Craton. The Sichuan basin, to the northeast of the EMP, is a superimposed basin composed of Paleozoic marine carbonate rocks and Mesozoic-Cenozoic terrestrial clastic rocks. The vitrinite reflectance (Ro) data as a paleogeothermal indicator records an apparent change of thermal regime of the Sichuan basin. The Ro profiles from boreholes and outcrops which are close to the center of the basalt province exhibit a 'dog-leg' style at the unconformity between the Middle and Upper Permian, and they show significantly higher gradients in the lower subsection (pre-Middle Permian) than the Upper subsection (Upper Permian to Mesozoic). Thermal history inversion based on these Ro data shows that the lower subsection experienced a heat flow peak much higher than that of the upper subsection. The abnormal heat flow in the Sichuan basin is consistent with the EMP in temporal and spatial distribution. The high-temperature magmas from deep mantle brought heat to the base of the lithosphere, and then large amount of heat was conducted upwards, resulting in the abnormal high surface heat flow.

High-resolution hydro- and geo-stratigraphy at Atlantic Coastal Plain drillhole CR-622 (Strat 8)

USGS Publications Warehouse

Wrege, B.M.; Isely, J.J.

2009-01-01

We interpret borehole geophysical logs in conjunction with lithology developed from continuous core to produce high-resolution hydro- and geo-stratigraphic profiles for the drillhole CR-622 (Strat 8) in the Atlantic Coastal Plain of North Carolina. The resulting hydrologic and stratigraphic columns show a generalized relation between hydrologic and geologic units. Fresh-water aquifers encountered are the surficial, Yorktown, Pungo River and Castle Hayne. Geologic units present are of the middle and upper Tertiary and Quaternary periods, these are the Castle Hayne (Eocene), Pungo River (Miocene), Yorktown (Pliocene), James City and Flanner Beach (Pleistocene), and the topsoil (Holocene). The River Bend Formation (Oligocene) is missing as a distinct unit between the Pungo River Formation and the Castle Hayne Formation. The confining unit underlying the Yorktown Aquifer corresponds to the Yorktown Geologic Unit. The remaining hydrologic units and geologic units are hydrologically transitional and non-coincident. The lower Pungo River Formation serves as the confining unit for the Castle Hayne Aquifer, rather than the River Bend Aquifer, and separates the Pungo River Aquifer from the upper Castle Hayne Aquifer. All geologic formations were bound by unconformities. All aquifers were confined by the anticipated hydrologic units. We conclude that CR-622 (Strat 8) represents a normal sequence in the Atlantic Coastal Plain.

Upper limb musculoskeletal complaints among technicians working in a diagnostic tuberculosis laboratory: two case reports.

PubMed

Wong, Joyce Y P; Chin, David; Fung, Henry; Li, Ann; Wong, Marcus M S; Kwok, Henry K H

2014-01-01

Upper limb musculoskeletal complaints are common among certain health professionals. We report two cases, both involving technicians working in a diagnostic tuberculosis laboratory in Hong Kong. A work process evaluation suggest that the need to repeatedly open and close small bottles, as well as to work for prolonged periods of time in confined areas, could be related to the workers' clinical presentation. The cases are also compatible with the diagnosis of repetitive strain injury (RSI) of the upper limb, but this term is not commonly used nowadays because of various definitional issues. A review of the various diagnostic issues in RSI is presented.

Petrography and geochemistry of clastic sedimentary rocks as evidences for provenance of the Lower Cambrian Lalun Formation, Posht-e-badam block, Central Iran

NASA Astrophysics Data System (ADS)

Etemad-Saeed, N.; Hosseini-Barzi, M.; Armstrong-Altrin, John S.

2011-09-01

Petrography and geochemistry (major, trace and rare earth elements) of clastic rocks from the Lower Cambrian Lalun Formation, in the Posht-e-badam block, Central Iran, have been investigated to understand their provenance. Petrographical analysis suggests that the Lalun conglomerates are dominantly with chert clasts derived from a proximal source, probably chert bearing Precambrian Formations. Similarly, purple sandstones are classified as litharenite (chertarenite) and white sandstones as quartzarenite types. The detrital modes of purple and white sandstones indicate that they were derived from recycled orogen (uplifted shoulders of rift) and stable cratonic source. Most major and trace element contents of purple sandstones are generally similar to upper continental crust (UCC) values. However, white sandstones are depleted in major and trace elements (except SiO 2, Zr and Co) relative to UCC, which is mainly due to the presence of quartz and absence of other Al-bearing minerals. Shale samples have considerably lower content in most of the major and trace elements concentration than purple sandstones, which is possibly due to intense weathering and recycling. Modal composition (e.g., quartz, feldspar, lithic fragments) and geochemical indices (Th/Sc, La/Sc, Co/Th, Cr/Th, Cr/V and V/Ni ratios) of sandstones, and shales (La/Sc and La/Cr ratios) indicate that they were derived from felsic source rocks and deposited in a passive continental margin. The chondrite-normalized rare earth element (REE) patterns of the studied samples are characterized by LREE enrichment, negative Eu anomaly and flat HREE similar to an old upper continental crust composed chiefly of felsic components in the source area. The study of paleoweathering conditions based on modal composition, chemical index of alteration (CIA), plagioclase index of alteration (PIA) and A-CN-K (Al 2O 3 - CaO + Na 2O - K 2O) relationships indicate that probably chemical weathering in the source area and recycling processes have been more important in shale and white sandstones relative to purple sandstones. The results of this study suggest that the main source for the Lalun Formation was likely located in uplifted shoulders of a rifted basin (probably a pull-apart basin) in its post-rift stage (Pan-African basement of the Posht-e-badam block).

Geologic framework of pre-Cretaceous rocks in the Southern Ute Indian Reservation and adjacent areas, southwestern Colorado and northwestern New Mexico

USGS Publications Warehouse

Condon, Steven M.

1992-01-01

This report is a discussion and summary of Jurassic and older rocks in the Southern Ute Indian Reservation and adjacent areas, southwestern Colorado and northwestern New Mexico, and is based on analysis of geophysical logs and observations of outcrops. The Reservation, which is located in the northern San Juan Basin, has been the site of deposition of sediments for much of the Phanerozoic. Geologic times represented on the Reservation are the Precambrian, Cambrian, Devonian, Mississippian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Tertiary, and Quaternary. Rocks of Ordovician and Silurian age have not been reported in this region. Thicknesses of pre-Cretaceous sedimentary rocks range from about 750 feet (229 meters) on the Archuleta arch, east of the Reservation, to more than 8,300 feet (2,530 meters) just northwest of the Reservation. About 5,500 feet (1,676 meters) of pre-Cretaceous sedimentary rocks occur in the central part of the Reservation, near Ignacio. At Ignacio the top of the Jurassic lies at a depth of 7,600 feet (2,316 meters) below the surface, which is composed of Tertiary rocks. As much as 2,500 feet (762 meters) of Tertiary rocks occur in the area. More than 10,000 feet (3,048 meters) of Cretaceous and younger rocks, and 15,600 feet (4,755 meters) of all Phanerozoic sedimentary rocks occur in the vicinity of the Reservation. In the early Paleozoic the area that includes the Southern Ute Reservation was on the stable western shelf of the craton. During this time sediments that compose the following shallow-marine clastic and carbonate rocks were deposited: the Upper Cambrian Ignacio Quartzite (0-150 feet; 0-46 meters), Upper Devonian Elbert Formation (50-200 feet; 15-61 meters), Upper Devonian Ouray Limestone (10-75 feet; 3-23 meters), and Mississippian Leadville Limestone (0-250 feet; 0-76 meters). Mixed carbonate and clastic deposition, which was punctuated by a unique episode of deposition of evaporite sediments, continued through the Pennsylvanian after a significant episode of erosion at the end of the Mississippian. Pennsylvanian rocks on the Reservation are the Molas Formation (20-100 feet; 6-30 meters) and Hermosa Group (400-2,800 feet; 122-853 meters), which consists of the Pinkerton Trail Formation (40-120 feet; 12-36 meters), Paradox Formation and equivalent rocks (200-1,800 feet; 61-549 meters), and Honaker Trail Formation (200-1,300 feet; 61-396 meters). A unit that is transitional between the Pennsylvanian and Permian is the Rico Formation, which is about 200 feet (61 meters) thick across most of the Reservation area. The close of the Paleozoic Era was marked by a great influx of arkosic clastic sediments from uplifted highlands to the north of the Reservation area during the Permian. Near the paleomountain front the Cutler Formation (presently as thick as 8,000 feet; 2,438 meters) formed as a result of deposition of arkosic sediments; however, the original thickness of the Cutler is unknown due to an unconformity at its top. In the area of the Reservation the Cutler has group status and has been divided into several formations: the Halgaito Formation (350-800 feet; 107-244 meters), Cedar Mesa Sandstone and equivalent rocks (150-350 feet; 46-107 meters), Organ Rock Formation (500-900 feet; 152-274 meters), and De Chelly Sandstone (0-100 feet; 0-30 meters). The sediments of these formations were deposited in a variety of environments, including eolian, mud-flat, and fluvial systems. Following an episode of erosion in the Early and Middle(?) Triassic, deposition in the area of the Southern Ute Reservation continued during the Mesozoic. Sediments of the Upper Triassic Dolores and correlative Chinle Formations were deposited in fluvial, lacustrine, and minor eolian environments. On the Reservation the Dolores is 500-1,200 feet (152-366 meters) thick. Lower Jurassic eolian and fluvial deposits may have been present in much of the Reservation area but have been removed

Discriminating Sediment Supply versus Accommodation Controls on Late Cretaceous Foreland Basin Stratigraphic Architecture in the Book Cliffs, Utah using Detrital Zircon Double Dating

NASA Astrophysics Data System (ADS)

Bartschi, N.; Saylor, J. E.

2016-12-01

Middle to late Campanian strata of the Book Cliffs, Utah record the Late Cretaceous deposition of three clastic wedges in the North American Cordilleran foreland basin east of the Sevier thrust-belt. Variations in wedge geometries provide an opportunity to evaluate the effects of sediment supply versus accommodation on foreland basin stratal architecture. There is a significant increase in eastward progradation rate from the Lower to the Upper Castlegate Sandstone. However, the progradation rate decreases in the overlying Bluecastle and Price River formations, as well as the laterally equivalent Farrer and Tuscher formations. Rapid progradation during Upper Castlegate deposition may be caused by increased sediment supply from either rapid exhumation of the Sevier thrust-belt or introduction of a new sediment source. Alternatively, reduced accommodation within the proximal foreland basin from uplifts associated with Laramide deformation, or a transition from flexural to dynamic subsidence, could produce the observed rapid wedge progradation. Changes in sediment provenance and source-area exhumation rate can be identified using a combination of detrital zircon U-Pb geochronology and (U-Th)/He thermochronology. Quantitative comparisons between collected samples and published provenance data indicates an upsection increase in a new sediment source, revealing a significant overall shift in provenance between wedge boundaries. This change in provenance is coupled by an upsection decrease in lag time between the Lower and Upper Castlegate, consistent with an increase in exhumation rate. Conversely, there is no change in lag time between the Upper Castlegate and overlying Price River Formation, suggesting a relatively constant exhumation rate. Near-zero lag times during the Upper Castlegate is consistent with rapid exhumation associated with increased thrusting of the Sevier thrust-belt. Therefore, progradation of the Upper Castlegate can be attributed to an increase in sediment supply due to both rapid exhumation of the Sevier thrust-belt and introduction of a new sediment source. However, the data do not rule out the potential influence of reduced accommodation associated with early Laramide deformation during Upper Castlegate deposition.

Confinement of the solar tachocline by a cyclic dynamo magnetic field

NASA Astrophysics Data System (ADS)

Barnabé, Roxane; Strugarek, Antoine; Charbonneau, Paul; Brun, Allan Sacha; Zahn, Jean-Paul

2017-05-01

Context. The surprising thinness of the solar tachocline is still not understood with certainty today. Among the numerous possible scenarios suggested to explain its radial confinement, one hypothesis is based on Maxwell stresses that are exerted by the cyclic dynamo magnetic field of the Sun penetrating over a skin depth below the turbulent convection zone. Aims: Our goal is to assess under which conditions (turbulence level in the tachocline, strength of the dynamo-generated field, spreading mechanism) this scenario can be realized in the solar tachocline. Methods: We develop a simplified 1D model of the upper tachocline under the influence of an oscillating magnetic field imposed from above. The turbulent transport is parametrized with enhanced turbulent diffusion (or anti-diffusion) coefficients. Two main processes that thicken the tachocline are considered; either turbulent viscous spreading or radiative spreading. An extensive parameter study is carried out to establish the physical parameter regimes under which magnetic confinement of the tachocline that is due to a surface dynamo field can be realized. Results: We have explored a large range of magnetic field amplitudes, viscosities, ohmic diffusivities and thermal diffusivities. We find that, for large but still realistic magnetic field strengths, the differential rotation can be suppressed in the upper radiative zone (and hence the tachocline confined) if weak turbulence is present (with an enhanced ohmic diffusivity of η> 107-8 cm2/ s), even in the presence of radiative spreading. Conclusions: Our results show that a dynamo magnetic field can, in the presence of weak turbulence, prevent the inward burrowing of a tachocline subject to viscous diffusion or radiative spreading.

Geochemistry of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama

USGS Publications Warehouse

Sprinkle, Craig L.

1989-01-01

The chemical quality of the ground water in the Floridan aquifer system is determined primarily by mineral-water interaction. However, some changes in water quality have been imposed by development, particularly near coastal pumping centers. A total of 601 chemical analyses, all from different wells, most completed in the upper part of the aquifer system, were used to describe the variations in water chemistry and to study the processes responsible for observed changes. The Floridan aquifer system is a vertically continuous sequence of Tertiary carbonate rocks that are of generally high permeability and are hydraulically connected in varying degrees. The rocks are principally limestone and dolomite, but they grade into limy sands and clays near the aquifer system's updip limits. Major minerals in the aquifer system are calcite, dolomite, and, locally, gypsum or quartz; minor minerals include apatite, glauconite, and clay minerals such as kaolinite and montmorillonite. Trace amounts of metallic oxides or sulfides are present in some areas. The aquifer system consists of the Upper and Lower Floridan aquifers, separated in most places by a less permeable confining unit that has highly variable hydraulic properties. Only the Upper Floridan aquifer is present throughout the study area. Freshwater enters the aquifer system in outcrop areas located primarily in central Georgia and north-central Florida. Discharge occurs chiefly to streams and springs and, to a lesser extent, directly into the sea. Most of the flow into and out of the system takes place where it is unconfined or where the upper confining unit is thin. Secondary permeability developed by dissolution of aquifer material is most prominent in these areas of dynamic flow. Dissolved-solids concentrations in water from the Upper Floridan aquifer generally range from less than 25 milligrams per liter near outcrops to more than 25,000 milligrams per liter along the coasts. The dominant cations in the ground water are Ca2+, Mg2+, and Na+; the dominant anions are HCO3-, Cl-, and SO42-, The concentration of Ca2+ is controlled primarily by calcite saturation. Concentrations of Mg2+, NA+, and Cl- are highest where mixing of freshwater and saltwater occurs. Concentrations of HCO3- reflect the control of calcite solubility. The concentration of SO42- is highest where gypsiferous rock units are present in the aquifer system. The major geochemical processes that occur in the Upper Floridan aquifer, based on water-quality maps and computations using a geochemical model, are (1) dissolution of aquifer minerals toward equilibrium, (2) mixing of ground water with recharge, leakage, or seawater, (3) sulfate reduction, and (4) cation exchange between water and aquifer minerals. Similar processes apparently control minor dissolved constituents, although quantification is difficult with the available data. Statistical tests of available nutrient data indicate that concentrations of N (nitrogen) species in unconfined recharge areas may be increasing over time; more detailed studies of all N species are needed to test this hypothesis, however. Data on trace metals, radionuclides, and man-made organic contaminants are limited. Available data indicate that most freshwater within the Upper Floridan is potable, but detection of pesticides in a few samples indicates that the system is susceptible to contamination from the land surface in some areas, particularly where its upper confining unit is thin or absent. Geochemical models were used to examine changes in major chemical elements along selected ground-water paths within the Upper Floridan aquifer. Water in the Upper Floridan aquifer can be categorized into four hydrochemical facies, whose exact distribution is determined by confined or unconfined conditions of the aquifer and by chloride concentrations. The reaction models are considered plausible based on available chemical, isotopic, and hydrologic information, and they

Replication in plastic of three-dimensional fossils preserved in indurated clastic sedimentary rocks

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

Zapasink, H.T.; Johnston, P.A.

A new technique for replicating in plastic the fossils preserved in clastic rocks should now make available reliable morphologic and frequency data, comparable in quality to those derived from acid-prepared silicified faunas, for a major segment of the fossil record. The technique involves 3 steps: the dissolution of carbonate in fossiliferous rocks with hydrochloric acid, impregnation of resulting voids with liquid plastic, and dissolution of the rock matrix with hydrofluoric acid, leaving a concentrate of plastic-replaced fossils.

Water resources of Lincoln and Union counties, South Dakota

USGS Publications Warehouse

Niehus, C.A.

1994-01-01

Water resources of Lincoln and Union Counties occur as surface water in streams and lakes and ground water in ten major glacial and one major bedrock aquifers. The major surface-water sources are the Missouri and Big Sioux Rivers. Glacial aquifers contain about 4 million acre-feet of water in storage; 1.5 million acre-feet are contained in the Missouri aquifer. The Wall Lake, Shindler, and Upper Vemillion-Missouri aquifers are deeply buried, confined aquifers with average thicknesses ranging from 31 to 41 feet. The Harrisburg and Big Sioux aquifers are shallow, water-table aquifers with average thicknesses of 26 and 28 feet, respectively. The Parker-Centerville, Newton Hills, and Brule Creek aquifers are buried, confined aquifers with average thicknesses ranging from 33 to 36 feet. The Lower Vermillion-Missouri aquifer is a buried, confined aquifer with an average thickness of 99 feet. The Missouri aquifer is confined in the northeastern portion of the aquifer and is a shallow, water-table aquifer elsewhere with average cumulative thickness of 84 feet.

Hydrogeologic Framework and Occurrence and Movement of Ground Water in the Upper Humboldt River Basin, Northeastern Nevada

USGS Publications Warehouse

Plume, Russell W.

2009-01-01

The upper Humboldt River basin encompasses 4,364 square miles in northeastern Nevada, and it comprises the headwaters area of the Humboldt River. Nearly all flow of the river originates in this area. The upper Humboldt River basin consists of several structural basins, in places greater than 5,000 feet deep, in which basin-fill deposits of Tertiary and Quaternary age and volcanic rocks of Tertiary age have accumulated. The bedrock of each structural basin and adjacent mountains is composed of carbonate and clastic sedimentary rocks of Paleozoic age and crystalline rocks of Paleozoic, Mesozoic and Cenozoic age. The permeability of bedrock generally is very low except for carbonate rocks, which can be very permeable where circulating ground water has widened fractures through geologic time. The principal aquifers in the upper Humboldt River basin occur within the water-bearing strata of the extensive older basin-fill deposits and the thinner, younger basin-fill deposits that underlie stream flood plains. Ground water in these aquifers moves from recharge areas along mountain fronts to discharge areas along stream flood plains, the largest of which is the Humboldt River flood plain. The river gains flow from ground-water seepage to its channel from a few miles west of Wells, Nevada, to the west boundary of the study area. Water levels in the upper Humboldt River basin fluctuate annually in response to the spring snowmelt and to the distribution of streamflow diverted for irrigation of crops and meadows. Water levels also have responded to extended periods (several years) of above or below average precipitation. As a result of infiltration from the South Fork Reservoir during the past 20 years, ground-water levels in basin-fill deposits have risen over an area as much as one mile beyond the reservoir and possibly even farther away in Paleozoic bedrock.

Mealtime Manual for the Aged and Handicapped.

ERIC Educational Resources Information Center

Klinger, Judith Lannefeld; And Others

Specific techniques to alleviate difficulties encountered in routine kitchen tasks are described for the elderly and the handicapped, particularly those persons with upper extremity weakness or amputees, arthritis, incoordination, wheelchair confinement, loss of sensation, and limited vision. Helpful information is provided in areas of kitchen…

The New Dislocated Worker. Trends and Issues Alerts.

ERIC Educational Resources Information Center

Imel, Susan

In the past, worker displacement resulting from structural changes in the economy remained confined to industrial occupations such as manufacturing. The recent trends toward corporate restructuring, global competition, and military downsizing have created new groups of dislocated workers, including upper and middle management and military…

ELM elimination with Li powder injection in EAST discharges using the tungsten upper divertor

DOE PAGES

Maingi, R.; Hu, J. S.; Sun, Z.; ...

2018-01-05

Here, we report the first successful use of lithium (Li) to eliminate edge-localized modes (ELMs) with tungsten divertor plasma-facing components in the EAST device. Li powder injected into the scrape-off layer of the tungsten upper divertor successfully eliminated ELMs for 3–5 s in EAST. The ELM elimination became progressively more effective in consecutive discharges at constant lithium delivery rates, and the divertor D α baseline emission was reduced, both signatures of improved wall conditioning. A modest decrease in stored energy and normalized energy confinement was also observed, but the confinement relative to H98 remained well above 1, extending the previousmore » ELM elimination results via Li injection into the lower carbon divertor in EAST. These results can be compared with recent observations with lithium pellets in ASDEX-Upgrade that failed to mitigate ELMs, highlighting one comparative advantage of continuous powder injection for real-time ELM elimination.« less

ELM elimination with Li powder injection in EAST discharges using the tungsten upper divertor

NASA Astrophysics Data System (ADS)

Maingi, R.; Hu, J. S.; Sun, Z.; Tritz, K.; Zuo, G. Z.; Xu, W.; Huang, M.; Meng, X. C.; Canik, J. M.; Diallo, A.; Lunsford, R.; Mansfield, D. K.; Osborne, T. H.; Gong, X. Z.; Wang, Y. F.; Li, Y. Y.; EAST Team

2018-02-01

We report the first successful use of lithium (Li) to eliminate edge-localized modes (ELMs) with tungsten divertor plasma-facing components in the EAST device. Li powder injected into the scrape-off layer of the tungsten upper divertor successfully eliminated ELMs for 3-5 s in EAST. The ELM elimination became progressively more effective in consecutive discharges at constant lithium delivery rates, and the divertor D α baseline emission was reduced, both signatures of improved wall conditioning. A modest decrease in stored energy and normalized energy confinement was also observed, but the confinement relative to H98 remained well above 1, extending the previous ELM elimination results via Li injection into the lower carbon divertor in EAST (Hu et al 2015 Phys. Rev. Lett. 114 055001). These results can be compared with recent observations with lithium pellets in ASDEX-Upgrade that failed to mitigate ELMs (Lang et al 2017 Nucl. Fusion 57 016030), highlighting one comparative advantage of continuous powder injection for real-time ELM elimination.

ELM elimination with Li powder injection in EAST discharges using the tungsten upper divertor

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

Maingi, R.; Hu, J. S.; Sun, Z.

Here, we report the first successful use of lithium (Li) to eliminate edge-localized modes (ELMs) with tungsten divertor plasma-facing components in the EAST device. Li powder injected into the scrape-off layer of the tungsten upper divertor successfully eliminated ELMs for 3–5 s in EAST. The ELM elimination became progressively more effective in consecutive discharges at constant lithium delivery rates, and the divertor D α baseline emission was reduced, both signatures of improved wall conditioning. A modest decrease in stored energy and normalized energy confinement was also observed, but the confinement relative to H98 remained well above 1, extending the previousmore » ELM elimination results via Li injection into the lower carbon divertor in EAST. These results can be compared with recent observations with lithium pellets in ASDEX-Upgrade that failed to mitigate ELMs, highlighting one comparative advantage of continuous powder injection for real-time ELM elimination.« less

Water levels and artesian pressures in the Chad Basin of northeastern Nigeria, 1963-68

USGS Publications Warehouse

Carmalt, S.W.; Tibbitts, G.C.

1969-01-01

This report presents records of water levels and artesian pressures collected during 1963-68 on an observational network of 116 dug wells and boreholes (drilled wells) in the Chad Basin of northeastern Nigeria. The Chad Basin is underlain by the Chad Formation, a series of fluvio-lacustrine sediments which attain a thickness of 1,500 feet or more in Nigeria. Three water-bearing zones, designated Upper, Middle and Lower, have been identified in the Chad Formation of Nigeria. The Upper Zone aquifer, which contains water under both unconfined and confined conditions, provides the principal source of water to dug wells for domestic and village water supply. The Middle Zone aquifer is tapped by numerous deep boreholes (drilled wells) which provide water by artesian flow in more than 13,000 square miles of Nigeria north and east of Maiduguri. The Lower Zone, which is also confined has only been identified thus far (1969) in the vicinity of Maiduguri.

Method for isolating two aquifers in a single borehole

DOEpatents

Burklund, P.W.

1984-01-20

A method for isolating and individually instrumenting separate aquifers within a single borehole is disclosed. A borehole is first drilled from the ground surface, through an upper aquifer, and into a separating confining bed. A casing, having upper and lower sections separated by a coupling collar, is lowered into the borehole. The borehole is grouted in the vicinity of the lower section of the casing. A borehole is then drilled through the grout plug and into a lower aquifer. After the lower aquifer is instrumented, the borehole is grouted back into the lower portion of the casing. Then the upper section of the casing is unscrewed via the coupling collar and removed from the borehole. Finally, instrumentation is added to the upper aquifer and the borehole is appropriately grouted. The coupling collar is designed to have upper right-hand screw threads and lower left-hand screw thread, whereby the sections of the casing can be readily separated.

Method for isolating two aquifers in a single borehole

DOEpatents

Burklund, Patrick W.

1985-10-22

A method for isolating and individually instrumenting separate aquifers within a single borehole. A borehole is first drilled from the ground surface, through an upper aquifer, and into a separating confining bed. A casing, having upper and lower sections separated by a coupling collar, is lowered into the borehole. The borehole is grouted in the vicinity of the lower section of the casing. A borehole is then drilled through the grout plug and into a lower aquifer. After the lower aquifer is instrumented, the borehole is grouted back into the lower portion of the casing. Then the upper section of the casing is unscrewed via the coupling collar and removed from the borehole. Finally, instrumentation is added to the upper aquifer and the borehole is appropriately grouted. The coupling collar is designed to have upper right-hand screw threads and lower left-hand screw thread, whereby the sections of the casing can be readily separated.

Late quaternary sediments, minerals, and inferred geochemical history of Didwana Lake, Thar Desert, India

USGS Publications Warehouse

Wasson, R.J.; Smith, G.I.; Agrawal, D.P.

1984-01-01

Variations in clastic sediment texture, mineralogy of both evaporites formed at the surface and precipitates formed below the lake floor, and the relative chemical activities of the major dissolved components of the chemical precipitates, have allowed reconstruction of the history of salinity and water-level changes in Didwana Lake, Thar Desert, India. Hypersaline conditions prevailed at about the Last Glacial Maximum, with little evidence of clastic sediments entering the lake. Between ca. 13,000 and 6000 B.P. the lake level fluctuated widely, the lake alternately hypersaline and fresh, and clastic sediments were delivered to the lake at a low rate. Deep-water conditions occurred ca. 6000 B.P. and clastic influx increased abruptly. The water level dropped towards 4000 B.P. when the lake dried briefly. Since 4000 B.P. the lake has been ephemeral with a lowered rate of sedimentation and mildly saline conditions rather like those of today. This sequence of changes documented in the lake parallels changes in vegetation recorded in published pollen diagrams from both the Thar and the Arabian Sea. Correlation of the various lines of evidence suggests that the climate of the Last Glacial Maximum at Didwana was dry and windy with a weak monsson circulation. The monsson was re-established between ca. 13,000 and a little before 6000 B.P., and, when winter rainfall increased ca. 6000 B.P., the lake filled to its maximum depth. ?? 1984.

Eocene upper shoreface facies from the Circum-Rhodope belt, NE Greece: sedimentological evidence for an ancient rocky shore environment

NASA Astrophysics Data System (ADS)

Chatalov, Atanas; Ivanova, Daria; Bonev, Nikolay

2013-04-01

The studied Middle to Upper Eocene sequence (ca.60 m) is located in western part of the large Tertiary Thrace Basin. The crudely stratified rocks consist of granuly to cobbly gravel and calcareous matrix. The former originated solely from the underlying Lower Cretaceous Aliki Limestone. The matrix includes various bioclasts plus sand-sized lithics derived from the same limestones. The broken and abraded skeletal debris belong to the heterozoan association and testify to non-tropical environment with normal marine salinity and good bottom oxygenation. The monomict gravel implies a local source of clastics close to the marine depositional basin. The bulk of extrabasinal material was produced through erosion of a rocky shore during a transgressive phase as is revealed by the present-day proximity of Aliki Limestone exposures, unconformity boundary with the overlying Eocene rocks, variable thickness and limited surface occurrence of the clastic-carbonate sequence. The extraclasts were deposited within the upper shoreface zone which is proved by their poor sorting and good roundness, absence of imbrication and disc-shaped fragments, local occurrence of matrix-supported fabric, and presence of abundant fossil debris. The Eocene transgression flooded a cliffed coast consisting of Lower Cretaceous limestones. The uneven bottom profile of the shoreface zone predetermined the formation of a wave ravinement surface (e.g. Cattaneo and Steel, 2003). The ravinement occurred through coastal erosion and wave abrasion as the shoreface shifted landward along with the rising sea level and shoreline retreat. The generated extraclasts were continuously reworked by wave motion and finally deposited as a mixture with shallow water bioclasts (also strongly reworked). The formation of a thick transgressive sequence was favoured by the interplay of several major factors as a persistent balance between sediment supply and accommodation development is inferred. The lack of vertical lithofacies transitions, small-scale cycles, and internal key stratal surfaces in the Eocene rocks testifies that the upper shoreface deposits were accumulated during a single transgressive phase. The particular absence of convincingly recognized beachface facies can be explained with the so called "cannibalization" mechanism (cf. Sheppard, 2006). The present-day exposures of the basement and covering rocks are consistent with the assumption of a paleoisland having homogeneous lithology. The prolonged erosional destruction of its rocky coast was gradually terminated and after the cessation of marine wave-cutting processes and contemporaneous deposition the remaining emerged cliffs of Lower Cretaceous limestones were continuously degraded by subaerial processes. The obtained results may elucidate the geological evolution of the hydrocarbon-bearing Thrace Basin and to promote the basin-wide correlation of its thick (~9000 m) sedimentary record. Acknowledgments: This study was supported by the National Science Fund of Bulgaria, Grant DDVU 02/94. References Cattaneo, A., R. J. Steel. 2003. Transgressive deposits: a review of their variability. - Earth Sci. Rev., 62, 187-228. Sheppard, T. H. 2006. Sequence architecture of ancient rocky shorelines and their response to sea-level change: an Early Jurassic example from South Wales, UK. - Jour. Geol. Soc. London, 163, 595-606.

Neogene stratigraphy, foraminifera, diatoms, and depositional history of Maria Madre Island, Mexico: Evidence of early Neogene marine conditions in the southern Gulf of California

USGS Publications Warehouse

McCloy, C.; Ingle, J.C.; Barron, J.A.

1988-01-01

Foraminifera and diatoms have been analyzed from an upper Miocene through Pleistocene(?) sequence of marine sediments exposed on Maria Madre Island, largest of the Tre??s Marias Islands off the Pacific coast of Mexico. The Neogene stratigraphic sequence exposed on Maria Madre Island includes a mid-Miocene(?) non-marine and/or shallow marine sandstone unconformably overlain by a lower upper Miocene to uppermost Miocene upper to middle bathyal laminated and massive diatomite, mudstone, and siltstone unit. This unit is unconformably overlain by lower Pliocene middle to lower bathyal sandstones and siltstones which, in turn, are unconformably overlain by upper Pliocene through Pleistocene(?) upper bathyal to upper middle bathyal foraminiferal limestones and siltstones. These beds are unconformably capped by Pleistocene terrace deposits. Basement rocks on the island include Cretaceous granite and granodiorite, and Tertiary(?) andesites and rhyolites. The upper Miocene diatomaceous unit contains a low diversity foraminiferal fauna dominated by species of Bolivina indicating low oxygen conditions in the proto-Gulf Maria Madre basin. The diatomaceous unit grades into a mudstone that contains a latest Miocene upper to middle bathyal biofacies characterized by Baggina californica and Uvigerina hootsi along with displaced neritic taxa. An angular unconformity separates the upper Miocene middle bathyal sediments from overlying lower Pliocene siltstones and mudstones that contain a middle to lower bathyal biofacies and abundant planktonic species including Neogloboquadrina acostaensis and Pulleniatina primalis indicating an early Pliocene age. Significantly, this Pliocene unit contains common occurrences of benthic species restricted to Miocene sediments in California including Bulimina uvigerinaformis. Pliocene to Pleistocene(?) foraminiferal limestones and siltstones characterize submarine bank accumulations formed during uplift of the Tre??s Marias Island area, and include abundant planktonic foraminifera such as Pulleniatina obliquiloculata and Neogloboquadrina duterteri. Common benthic foraminifera in this unit are indicative of upper bathyal water depths. The Neogene depositional history recorded on Maria Madre Island involves an early late Miocene subsidence event marking formation of the Tre??s Marias Basin with relatively undiluted diatomaceous sediment deposited in a low oxygen setting. Subsidence and deepening of the basin continued into the early Pliocene along with rapid deposition of terrigenous clastics. Uplift of the basinal sequence began in late Pliocene time accompanied by deposition of upper Pliocene-Pleistocene foraminiferal limestones on a rising submarine bank. Continued episodic uplift of the Neogene deposits brought the island above sea level by late Pleistocene time. ?? 1988.

Geohydrology and evaluation of water-resource potential of the upper Floridan Aquifer in the Albany area, southwestern Georgia

USGS Publications Warehouse

Torak, L.J.; Davis, G.S.; Strain, G.A.; Herndon, J.G.

1993-01-01

In the Albany area of southwestern Georgia, the Upper Floridan aquifer lies entirely within the Dougherty Plain district of the Coastal Plain physiographic province, and consists of the Ocala Limestone of late Eocene age. The aquifer is divided throughout most of the study area into an upper and a lower lithologic unit, which creates an upper and a lower water-bearing zone. The lower waterbearing zone consists of alternating layers of sandy limestone and medium-brown, recrystallized dolomitic limestone, and ranges in thickness from about 50 ft to 100 ft. It is highly fractured and exhibits well-developed permeability by solution features that are responsible for transmitting most of the ground water in the aquifer. Transmissivity of the lower water-bearing zone ranges from about 90,000 to 178,000 ft2/d. The upper water-bearing zone is a finely crystallized-to-oolitic, locally dolomitic limestone having an average thickness of about 60 ft. Transmissivities are considerably less in the upper water-bearing zone than in the lower water-bearing zone. The Upper Floridan aquifer is overlain by about 20-120 ft of undifferentiated overburden consisting of fine-to-coarse quartz sand and noncalcareous clay. A clay zone about 10-30 ft thick may be continuous throughout the southwestern part of the Albany area and, where present, causes confinement of the Upper Floridan aquifer and creates perched ground water after periods of heavy rainfall. The Upper Floridan aquifer is confined below by the Lisbon Formation, a mostly dolomitic limestone that contains trace amounts of glauconite. The Lisbon Formation is at least 50 ft thick in the study area and acts as an impermeable base to the Upper Floridan aquifer. The quality of ground water in the Upper Floridan aquifer is suitable for most uses; wells generally yield water of the hard, calcium-bicarbonate type that meets the U.S. Environmental Protection Agency's Primary or Secondary Drinking-Water Regulations. The water-resource potential of the Upper Floridan aquifer was evaluated by compiling results of drilling and aquifer testing in the study area, and by conducting computer simulations of the ground-water flow system under the seasonally low conditions of November 1985, and under conditions of pumping within a 12-mi 2 area located southwest of Albany. Results of test drilling, aquifer testing, and water-quality analyses indicate that, in the area southwest of Albany, geohydrologic conditions in the Upper Floridan aquifer, undifferentiated overburden, and Lisbon Formation were favorable for the aquifer to provide a large quantity of water without having adverse effects on the groundwater system. The confinement of the Upper Floridan aquifer by the undifferentiated overburden and the rural setting of the area of potential development decrease the likelihood that chemical constituents will enter the aquifer during development of the ground-water resources. Computer simulations of ground-water flow in the Upper Floridan aquifer, incorporating conditions for regional flow across model boundaries, leakage from rivers and other surface-water features, and vertical leakage from the undifferentiated overburden, were conducted by using a finite-element model for ground-water flow in two dimensions. Comparison of computed and measured water levels in the Upper Floridan aquifer for November 1985 at 74 locations indicated that computed water levels generally were within 5 ft of the measured values, which is the accuracy to which measured water levels were known. Water-level altitudes ranged from about 260 ft to 130 ft above sea level in the study area during calibration. Aquifer discharge to the Flint River downstream from the Lake Worth dam was computed by the calibrated model to be about 1 billion gallons per day; about 300 million gallons per day (Mgal/d) greater than was measured for similar lowflow conditions. The excess computed discharge was attributed partially to stream withdrawals for

Observed stratospheric downward reflection, and its relation to upward pulses of wave activity

NASA Astrophysics Data System (ADS)

Harnik, N.

2009-04-01

We examine the differences between observed stratospheric vertical wave reflection and wave absorption events, which differ in that the wave induced deceleration remains confined to upper levels in the former. The two types of events signify two types of stratospheric winter dynamics, associated with different downward coupling to the troposphere (Perlwitz and Harnik, 2004). Using time lag composites, we find that the main factor influencing which event will occur is the duration, in time, of the upward pulse of wave activity entering the stratosphere from the troposphere. Short pulses accelerate the flow at their trailing edge in the lower stratosphere while they decelerate it at upper levels, resulting in a vertical shear reversal, and corresponding downward reflection, while long pulses continue decelerating the vortex at progressively lower levels. The confinement of deceleration to upper levels for short wave forcing pulses is also found in an idealized model of an interaction between a planetary wave and the stratospheric vortex, though some aspects of the wave geometry evolution, and thus vertical reflection, are not captured realistically in the model. The results suggest the stratospheric influence on the type of wave interaction, in reality, is indirect - through a possible effect on the duration of upward wave fluxes through the tropopause.

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, September 2006

USGS Publications Warehouse

Ortiz, A.G.

2007-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2006. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 46.06 inches for west-central Florida (from October 2005 through September 2006) was 6.91 inches below the historical cumulative average of 52.97 inches (Southwest Florida Water Management District, 2006). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during September 18-22, 2006. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman, 2007). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal high water-level condition.

Potentiometric surface of the Upper Floridan aquifer, west-central Florida, September 2005

USGS Publications Warehouse

Ortiz, A.G.

2006-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public-supply, domestic use, irrigation, and brackish-water desalination in coastal communities (Southwest Florida Water Management District, 2000).This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2005. The potentiometric surface is an imaginary surface, connecting points of equal altitude to which water will rise in tightly cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 55.19 inches for west-central Florida (from October 2004 through September 2005) was 2.00 inches above the historical cumulative average of 53.19 inches (Southwest Florida Water Management District, 2005). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District.This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period September 19-23, 2005. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Altamonte Springs, Florida (Kinnaman, 2006). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a "snapshot" of conditions at a specific time, nor do they necessarily coincide with the seasonal high water-level condition.

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, September 2007

USGS Publications Warehouse

Ortiz, A.G.

2008-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2007. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 39.50 inches for west-central Florida (from October 2006 through September 2007) was 13.42 inches below the historical cumulative average of 52.92 inches (Southwest Florida Water Management District, 2007). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period September 17-21, 2007. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman and Dixon, 2008). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal high water-level condition.

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, September 2008

USGS Publications Warehouse

Ortiz, Anita G.

2009-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2008. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 50.63 inches for west-central Florida (from October 2007 through September 2008) was 2.26 inches below the historical cumulative average of 52.89 inches (Southwest Florida Water Management District, 2008). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period September 15-19, 2008. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman and Dixon, 2009). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal high water-level condition.

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, May 2008

USGS Publications Warehouse

Ortiz, A.G.

2008-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2008. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 46.95 inches for west-central Florida (from June 2007 through May 2008) was 5.83 inches below the historical cumulative average of 52.78 inches (Southwest Florida Water Management District, 2008). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 19-23, 2008. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman and Dixon, 2008). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition.

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, May 2007

USGS Publications Warehouse

Ortiz, A.G.

2008-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2007. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 41.21 inches for west-central Florida (from June 2006 through May 2007) was 11.63 inches below the historical cumulative average of 52.84 inches (Southwest Florida Water Management District, 2007). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 21-25, 2007. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman and Dixon, 2007). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition.

Generalized analytical model for benthic water flux forced by surface gravity waves

USGS Publications Warehouse

King, J.N.; Mehta, A.J.; Dean, R.G.

2009-01-01

A generalized analytical model for benthic water flux forced by linear surface gravity waves over a series of layered hydrogeologic units is developed by adapting a previous solution for a hydrogeologic unit with an infinite thickness (Case I) to a unit with a finite thickness (Case II) and to a dual-unit system (Case III). The model compares favorably with laboratory observations. The amplitude of wave-forced benthic water flux is shown to be directly proportional to the amplitude of the wave, the permeability of the hydrogeologic unit, and the wave number and inversely proportional to the kinematic viscosity of water. A dimensionless amplitude parameter is introduced and shown to reach a maximum where the product of water depth and the wave number is 1.2. Submarine groundwater discharge (SGD) is a benthic water discharge flux to a marine water body. The Case I model estimates an 11.5-cm/d SGD forced by a wave with a 1 s period and 5-cm amplitude in water that is 0.5-m deep. As this wave propagates into a region with a 0.3-m-thick hydrogeologic unit, with a no-flow bottom boundary, the Case II model estimates a 9.7-cm/d wave-forced SGD. As this wave propagates into a region with a 0.2-m-thick hydrogeologic unit over an infinitely thick, more permeable unit, the Case III quasi-confined model estimates a 15.7-cm/d wave-forced SGD. The quasi-confined model has benthic constituent flux implications in coral reef, karst, and clastic regions. Waves may undermine tracer and seepage meter estimates of SGD at some locations. Copyright 2009 by the American Geophysical Union.

Cosmogenic He and Ne in chondrules from clastic matrix and a lithic clast of Murchison: No pre-irradiation by the early sun

NASA Astrophysics Data System (ADS)

Riebe, My E. I.; Huber, Liliane; Metzler, Knut; Busemann, Henner; Luginbuehl, Stefanie M.; Meier, Matthias M. M.; Maden, Colin; Wieler, Rainer

2017-09-01

Whether or not some meteorites retain a record of irradiation by a large flux of energetic particles from the early sun in the form of excesses of cosmic-ray produced noble gases in individual crystals or single chondrules is a topic of ongoing debate. Here, we present He and Ne isotopic data for individual chondrules in Murchison, a chondritic regolith breccia of the CM group. We separated 27 chondrules from a clastic matrix portion and 26 chondrules from an adjacent single so-called "primary accretionary rock" (Metzler et al., 1992). All chondrules from the primary rock fragment are expected to share a common irradiation history, whereas chondrules from the clastic matrix were stirred in the regolith independently of each other. All "primary rock chondrules" and 23 of the "matrix chondrules" have very similar concentrations of cosmogenic 3He and 21Ne, corresponding to a cosmic-ray exposure age to galactic cosmic rays (GCR) of ∼1.3-1.9 Ma, in the range of Murchison's meteoroid exposure age determined with cosmogenic radionuclides. Four clastic matrix chondrules contain excesses of cosmogenic 3He and 21Ne, corresponding to nominal 4π exposure ages of ∼4-∼29 Ma, with a Ne isotopic composition as expected for production by GCR. If the fraction of excess cosmogenic gas bearing chondrules in the primary rock and clastic matrix were the same, we would expect this result with a statistical probability of only 0.5 - 2.7%. Therefore, the exposure age distributions for Murchison chondrules in primary rock and clastic matrix are very likely different. Such a difference is expected if the excess cosmogenic gas was acquired by some of the matrix chondrules in the regolith, but not if chondrules were irradiated in the solar nebula by the early sun before they accreted on the Murchison parent body. Therefore, Murchison does not provide evidence for irradiation by a high fluence of energetic particles from the early sun. By inference, this statement likely holds for the other regolithic meteorites for which large occasional excesses of cosmogenic noble gases have been reported. Considering pre-irradiation in a regolith (2π exposure), the pre-exposure times for these four chondrules are at least between some 4 and 40 Ma near the very surface of the parent body, and even longer if they were buried deeper in the regolith.

Eustatic and tectonic control of deposition of the lower and middle Pennsylvanian strata of the Central Appalachian Basin

USGS Publications Warehouse

Chesnut, D.R.

1997-01-01

Stratigraphic analysis of Lower and Middle Pennsylvanian rocks of part of the Central Appalachian Basin reveals two orders of cycles and one overall trend in the vertical sequence of coal-bearing rocks. The smallest order cycle, the coal-clastic cycle, begins at the top of a major-resource coal bed and is composed of a vertical sequence of shale, siltstone, sandstone, seat rock, and overlying coal, which, in turn, is overlain by the next coal-clastic sequence. The average duration of the coal-clastic cycle has been calculated to be about 0.4 m.y. The major marine-transgression cycle is composed of five to seven coal-clastic cycles and is distinguished by the occurrence of widespread, relatively thick (generally thicker than 5 m) marine strata at its base. The duration of this cycle has been calculated to be about 2.5 m.y. The Breathitt coarsening-upward trend describes the general upward coarsening of the Middle Pennsylvanian part of the Breathitt Group. The Breathitt Group includes eight major marine-transgression cycles, and was deposited during a period of approximately 20 m.y. The average duration of coal-clastic cycles is of the same order of magnitude (105 year) as the Milankovitch orbital-eccentricity cycles, and matches the 0.4 m.y. second-order eccentricity cycle (Long Earth-Eccentricity cycle). These orbital periodicities are thought to modulate glacial stages and glacio-eustatic levels. The calculated periodicities of the coal-clastic cycles can be used as evidence for glacio-eustatic control of the coal-bearing rocks of the Appalachian Basin. The 2.5-m.y. periodicity of the major marine-transgression cycle does not match any known orbital or tectonic cycle; the cause of this cycle is unknown, but it might represent episodic thrusting in the orogen, propagation of intraplate stresses, or an unidentified orbital cycle. The Breathitt coarsening-upward trend is interpreted to represent the increasing intensity and proximity of the Alleghenian Orogeny. Previously, tectonic subsidence of the basin was considered to be the dominant control on deposition of the coal-bearing rocks of the basin. However, new calculations show that eustatic rates are more significant than averaged subsidence rates for the Pennsylvanian Appalachian Basin. Accordingly, sea-level changes are considered to be a dominant control on coastal sedimentation during the Pennsylvanian. However, tectonic subsidence created the accomodation space for preservation of various orders of cyclic sedimentation; the preserved order of cycles was dependent upon the rate of subsidence from basin margin to axis.

41 CFR 102-80.145 - What is meant by “flashover”?

Code of Federal Regulations, 2010 CFR

2010-07-01

...”? Flashover means fire conditions in a confined area where the upper gas layer temperature reaches 600 °C (1100 °F) and the heat flux at floor level exceeds 20 kW/m2 (1.8 Btu/ft2/sec). Reasonable Worst Case...

41 CFR 102-80.145 - What is meant by “flashover”?

Code of Federal Regulations, 2011 CFR

2011-01-01

...”? Flashover means fire conditions in a confined area where the upper gas layer temperature reaches 600 °C (1100 °F) and the heat flux at floor level exceeds 20 kW/m2 (1.8 Btu/ft2/sec). Reasonable Worst Case...

Concurrent Preoperative Presence of Hydronephrosis and Flank Pain Independently Predicts Worse Outcome of Upper Tract Urothelial Carcinoma.

PubMed

Yeh, Hsin-Chih; Jan, Hau-Chern; Wu, Wen-Jeng; Li, Ching-Chia; Li, Wei-Ming; Ke, Hung-Lung; Huang, Shu-Pin; Liu, Chia-Chu; Lee, Yung-Chin; Yang, Sheau-Fang; Liang, Peir-In; Huang, Chun-Nung

2015-01-01

To investigate the impact of preoperative hydronephrosis and flank pain on prognosis of patients with upper tract urothelial carcinoma. In total, 472 patients with upper tract urothelial carcinoma managed by radical nephroureterectomy were included from Kaohsiung Medical University Hospital Healthcare System. Clinicopathological data were collected retrospectively for analysis. The significance of hydronephrosis, especially when combined with flank pain, and other relevant factors on overall and cancer-specific survival were evaluated. Of the 472 patients, 292 (62%) had preoperative hydronephrosis and 121 (26%) presented with flank pain. Preoperative hydronephrosis was significantly associated with age, hematuria, flank pain, tumor location, and pathological tumor stage. Concurrent presence of hydronephrosis and flank pain was a significant predictor of non-organ-confined disease (multivariate-adjusted hazard ratio = 2.10, P = 0.025). Kaplan-Meier analysis showed significantly poorer overall and cancer-specific survival in patients with preoperative hydronephrosis (P = 0.005 and P = 0.026, respectively) and in patients with flank pain (P < 0.001 and P = 0.001, respectively) than those without. However, only simultaneous hydronephrosis and flank pain independently predicted adverse outcome (hazard ratio = 1.98, P = 0.016 for overall survival and hazard ratio = 1.87, P = 0.036 for and cancer-specific survival, respectively) in multivariate Cox proportional hazards models. In addition, concurrent presence of hydronephrosis and flank pain was also significantly predictive of worse survival in patient with high grade or muscle-invasive disease. Notably, there was no difference in survival between patients with hydronephrosis but devoid of flank pain and those without hydronephrosis. Concurrent preoperative presence of hydronephrosis and flank pain predicted non-organ-confined status of upper tract urothelial carcinoma. When accompanied with flank pain, hydronephrosis represented an independent predictor for worse outcome in patients with upper tract urothelial carcinoma.

A 1.3-μm four-channel directly modulated laser array fabricated by SAG-Upper-SCH technology

NASA Astrophysics Data System (ADS)

Guo, Fei; Lu, Dan; Zhang, Ruikang; Liu, Songtao; Sun, Mengdie; Kan, Qiang; Ji, Chen

2017-01-01

A monolithically integrated four-channel directly modulated laser (DML) array working at the 1.3-μm band is demonstrated. The laser was manufactured by using the techniques of selective area growth (SAG) of the upper separate confinement heterostructure (Upper-SCH) and modified butt-joint method. The fabricated device showed stable single mode operation with the side mode suppression ratio (SMSR) >35 dB, and high wavelength accuracy with the deviations from the linear fitted values <±0.03 nm for all channels. Furthermore, small signal modulation bandwidth >7 GHz was obtained, which may be suitable for 40 GbE applications in the 1.3-μm band.

Hydrogeologic framework and simulation of ground-water flow and travel time in the shallow aquifer system in the area of Naval Support Activity Memphis, Millington, Tennessee

USGS Publications Warehouse

Robinson, James L.; Carmichael, John K.; Halford, Keith J.; Ladd, David E.

1997-01-01

Naval Support Activity (NSA) Memphis is a Department of the Navy facility located at the City of Millington, Tennessee, about 5 miles north of Memphis. Contaminants have been detected in surface-water, sediment, and ground-water samples collected at the facility. As part of the Installation Restoration Program, the Navy is considering remedial-action options to prevent or lessen the effect of ground-water contamination at the facility and to control the movement and discharge of contaminants. A numerical model of the ground-water-flow system in the area of NSA Memphis was constructed and calibrated so that quantifiable estimates could be made of ground-water-flow rates, direction, and time-of-travel. The sediments beneath NSA Memphis, to a depth of about 200 feet, form a shallow aquifer system. From youngest to oldest, the stratigraphic units that form the shallow aquifer system are alluvium, loess, fluvial deposits, and the Cockfield and Cook Mountain Formations. The shallow aquifer system is organized into five hydrogeologic units: (1) a confining unit composed of the relatively low permeability sediments of the upper alluvium and the loess; (2) the A1 aquifer comprising sand and gravel of the lower alluvium and the fluvial deposits, and sand lenses in the upper part of the preserved section of the Cockfield Formation; (3) a confining unit composed of clay and silt within the upper part of the Cockfield Formation; (4) the Cockfield aquifer comprising sand lenses within the lower part of the preserved section of the Cockfield Formation; and (5) a confining unit formed by low permeability sediments of the Cook Mountain Formation that composes the upper confining unit for the Memphis aquifer. Thicknesses of individual units vary considerably across the facility. Structural and depositional features that affect the occurrence of ground water in the shallow aquifer system include faulting, an erosional scarp, and 'windows' in the confining units. Underlying the shallow aquifer system is the Memphis aquifer, the primary source of water for NSA Memphis and the City of Memphis, Tennessee. Analyses of sediment cores, aquifer and well specific-capacity tests, and numerical modeling were used to estimate the hydraulic characteristics of units of the shallow aquifer system. The vertical hydraulic conductivity of core samples of the alluvium-loess confining unit ranged from about 8.5 x 10-5 to 1.6 x 10-2 feet per day, and the total porosity of the samples ranged from about 35 to 48 percent. The results of the aquifer test were used to estimate a horizontal hydraulic conductivity of about 5 feet per day for the alluvial-fluvial deposits aquifer. The total porosity of core samples of the alluvial-fluvial deposits aquifer ranged from about 22 to 39 percent. The vertical hydraulic conductivity of core samples of the Cockfield confining unit ranged from about 4.5 x 10-5 to 2.5 x 10-3 feet per day, and the total porosity ranged from about 41 to 55 percent. Well specific-capacity tests indicate that the horizontal hydraulic conductivity of sand units that compose the Cockfield aquifer range from about 0.5 to 3 feet per day. The vertical hydraulic conductivity of core samples of the Cook Mountain confining unit ranged from about 5.0 x 10-6 to 9.9 x 10-4 feet per day. Total porosity of core samples of the Cook Mountain confining unit ranged from about 30 to 42 percent. Ground-water flow and time-of-travel in the shallow aquifer system were simulated using the MODFLOW finite-difference model and the -particle-tracking program MODPATH. A three-layer, steady-state model of the shallow aquifer system was constructed and calibrated to the potentiometric surface of the A1 aquifer. Results of numerical modeling support the proposed conceptual hydrogeologic model of the shallow aquifer system. Ground-water time-of-travel in the A1 aquifer was simulated using an assumed effective porosity of 25 percent. Typical ground-water-flow velocities were on the or

Toroidal midplane neutral beam armor and plasma limiter

DOEpatents

Kugel, Henry W.; Hand Jr, Samuel W.; Ksayian, Haig

1986-02-04

For use in a tokamak fusion reactor having a midplane magnetic coil on the inner wall of an evacuated toriodal chamber within which a neutral beam heated, fusing plasma is magnetically confined, a neutral beam armor shield and plasma limiter is provided on the inner wall of the toroidal chamber to shield the midplane coil from neutral beam shine-thru and plasma deposition. The armor shield/plasma limiter forms a semicircular enclosure around the midplane coil with the outer surface of the armor shield/plasma limiter shaped to match, as closely as practical, the inner limiting magnetic flux surface of the toroidally confined, indented, bean-shaped plasma. The armor shield/plasma limiter includes a plurality of semicircular graphite plates each having a pair of coupled upper and lower sections with each plate positioned in intimate contact with an adjacent plate on each side thereof so as to form a closed, planar structure around the entire outer periphery of the circular midplane coil. The upper and lower plate sections are adapted for coupling to heat sensing thermocouples and to a circulating water conduit system for cooling the armor shield/plasma limiter.The inner center portion of each graphite plate is adapted to receive and enclose a section of a circular diagnostic magnetic flux loop so as to minimize the power from the plasma confinement chamber incident upon the flux loop.

Toroidal midplane neutral beam armor and plasma limiter

DOEpatents

Kugel, Henry W.; Hand, Jr, Samuel W.; Ksayian, Haig

1986-01-01

For use in a tokamak fusion reactor having a midplane magnetic coil on the inner wall of an evacuated toriodal chamber within which a neutral beam heated, fusing plasma is magnetically confined, a neutral beam armor shield and plasma limiter is provided on the inner wall of the toroidal chamber to shield the midplane coil from neutral beam shine-thru and plasma deposition. The armor shield/plasma limiter forms a semicircular enclosure around the midplane coil with the outer surface of the armor shield/plasma limiter shaped to match, as closely as practical, the inner limiting magnetic flux surface of the toroidally confined, indented, bean-shaped plasma. The armor shield/plasma limiter includes a plurality of semicircular graphite plates each having a pair of coupled upper and lower sections with each plate positioned in intimate contact with an adjacent plate on each side thereof so as to form a closed, planar structure around the entire outer periphery of the circular midplane coil. The upper and lower plate sections are adapted for coupling to heat sensing thermocouples and to a circulating water conduit system for cooling the armor shield/plasma limiter.The inner center portion of each graphite plate is adapted to receive and enclose a section of a circular diagnostic magnetic flux loop so as to minimize the power from the plasma confinement chamber incident upon the flux loop.

Geologic history of the summit of Axial Seamount, Juan de Fuca Ridge

USGS Publications Warehouse

Clague, David A.; Dreyer, Brian M; Paduan, Jennifer B; Martin, Julie F; Chadwick, William W Jr; Caress, David W; Portner, Ryan A; Guilderson, Thomas P.; McGann, Mary; Thomas, Hans; Butterfield, David A; Embley, Robert W

2013-01-01

Multibeam (1 m resolution) and side scan data collected from an autonomous underwater vehicle, and lava samples, radiocarbon-dated sediment cores, and observations of flow contacts collected by remotely operated vehicle were combined to reconstruct the geologic history and flow emplacement processes on Axial Seamount's summit and upper rift zones. The maps show 52 post-410 CE lava flows and 20 precaldera lava flows as old as 31.2 kyr, the inferred age of the caldera. Clastic deposits 1–2 m thick accumulated on the rims postcaldera. Between 31 ka and 410 CE, there are no known lava flows near the summit. The oldest postcaldera lava (410 CE) is a pillow cone SE of the caldera. Two flows erupted on the W rim between ∼800 and 1000 CE. From 1220 to 1300 CE, generally small eruptions of plagioclase phyric, depleted, mafic lava occurred in the central caldera and on the east rim. Larger post-1400 CE eruptions produced inflated lobate flows of aphyric, less-depleted, and less mafic lava on the upper rift zones and in the N and S caldera. All caldera floor lava flows, and most uppermost rift zone flows, postdate 1220 CE. Activity shifted from the central caldera to the upper S rift outside the caldera, to the N rift and caldera floor, and then to the S caldera and uppermost S rift, where two historical eruptions occurred in 1998 and 2011. The average recurrence interval deduced from the flows erupted over the last 800 years is statistically identical to the 13 year interval between historical eruptions.

Recognition and delineation of Paleokarst zones by the use of wireline logs in the bitumen-saturated upper Devonian Grosmont formation of Northeastern Alberta, Canada

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

Dembicki, E.A.; Machel, H.G.

1996-05-01

The Upper Devonian Grosmont Formation in northeastern Alberta, Canada, is a shallow-marine carbonate platform complex that was subaerially exposed for hundreds of millions of years between the Mississippian(?) and Cretaceous. During this lengthy exposure period, an extensive karst system developed that is characterized by an irregular erosional surface, meter-size (several feet) dissolution cavities, collapse breccias, sinkholes, paleosols, and fractures. The karsted Grosmont Formation, which contains giant reserves of bitumen, sub-crops beneath Cretaceous clastic sediments of the giant Athabasca tar sands deposit. The paleokarst in the Grosmont Formation can be recognized on wireline logs in relatively nonargillaceous carbonate intervals (<30 APImore » units on the gamma-ray log) as excursions of the caliper log, off-scale neutron-density porosity readings, and severe cycle skipping of the acoustic log. The paleokarst is more prevalent in the upper units of the Grosmont Formation, and the effects of karstification decrease toward stratigraphically older and deeper units. The paleokarst usually occurs within 35 m (115 ft) of the erosional surface. The reservoir properties of the Grosmont Formation (e.g., thickness, porosity, permeability, and seal effectiveness) are significantly influenced by karstification. Depending upon the location, karstification has either benefited or degraded the reservoir characteristics. Benefits include porosity values greater than 40% (up to 100% in caverns) and permeability values of 30,000 md in severely fractured intervals. Detrimental reservoir characteristics include erosion, porosity and permeability reduction, and seal ineffectiveness.« less

Hydrogeologic setting, hydraulic properties, and ground-water flow at the O-Field area of Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Banks, W.S.; Smith, B.S.; Donnelly, C.A.

1996-01-01

The U.S. Army disposed chemical agents, laboratory materials, and unexploded ordnance at O-Field in the Edgewood area of Aberdeen Proving Ground, Maryland, from before World War II until at least the 1950's. Soil, ground water, surface water,and wetland sediments in the O-Field area were contaminated from the disposal activity. A ground-water-flow model of the O-Field area was constructed by the U.S. Geological Survey (USGS) in 1989 to simulate flow in the central and southern part of the Gunpowder Neck. The USGS began an additional study of the contamination in the O-Field area in cooperation with the U.S. Army in 1990 to (1) further define the hydrogeologic framework of the O-Field area, (2) characterize the hydraulic properties of the aquifers and confining units, and (3) define ground-water flow paths at O-Field based on the current data and simulations of ground-water flow. A water-table aquifer, an upper confining unit, and an upper confined aquifer comprise the shallow ground-water aquifer system of the O-Field area. A lower confining unit, through which ground-water movement is negligible, is considered a lower boundary to the shallow aquifer system. These units are all part of the Pleistocene Talbot Formation. The model developed in the previous study was redesigned using the data collected during this study and emphasized New O-Field. The current steady-state model was calibrated to water levels of June 1993. The rate of ground-water flow calculated by the model was approximately 0.48 feet per day (ft/d) and the rate determined from chlorofluorocarbon dates was approximately 0.39 ft/d.

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

USGS Publications Warehouse

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

1991-01-01

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

Hydrogeochemical and vertical electrical soundings for groundwater investigations, Burg El-Arab area, Northwestern Coast of Egypt

NASA Astrophysics Data System (ADS)

Atwia, Mohamed G.; Abu-Heleika, Mohamed M.; El-Horiny, Mohamed M.

2013-04-01

An integrated geological, hydrochemical, and geoelectrical investigation of shallow groundwater occurrence in Burg El-Arab area, northwestern coastal zone of Egypt is carried out. Groundwater of oolitic limestone and clastic aquifers is the principal source of water supply for agriculture in the area. The purpose of this study is to describe the hydrogeologic characteristics of aquifers and to provide a general evaluation of the chemical quality of water in aquifers. Chemical analysis was used to evaluate the chemical characteristics of groundwater and assessment of water quality. Electrical soundings were employed to delineate different water bearing formations and the configuration of the interface between them. Thirty-four water samples were collected and chemically analyzed from the two main aquifers in the area. Groundwaters of oolitic limestone aquifer are dominated by NaCl and have average TDS of approximately 2830 mg/l. Groundwater samples from clastic aquifer are slightly weakly mineralized (TDS approximately 2700 mg/l) and dominated by CaSO4. The hydrochemical data indicate that the groundwater is of meteoric origin. The variation in the chemistry of water is thought to be related to the weathering of minerals of the water-bearing sediments, mixing with marine water, and leaching of fertilizers in the newly reclaimed areas. Groundwater of the area can be used for irrigation under special circumstances management as the sodium hazard is medium while the salinity hazard ranges from high to very high. Thirty-four profiles of vertical electrical soundings (VESs) were obtained in Burg El-Arab area to examine the variations of subsurface geology and associated groundwater chemistry. Resistivity and thickness of aquifers, resistivity of the unsaturated zone and depth to the confining bed have been delineated from the interpretation of electrical sounding data. The range of electrical resistivity values have been assigned to different layers by calibrating electrical resistivity with the borehole data. Results of the vertical electrical soundings and the hydrochemistry of the groundwater samples show that the brackish groundwater is dominated in the study area whereas the fresh groundwater is found as isolated patches in oolitic limestone aquifer.

The Pliocene seamount series of La Palma/Canary Islands

NASA Astrophysics Data System (ADS)

Staudigel, Hubert; Schmincke, Hans-Ulrich

1984-12-01

A Pliocene submarine series of alkali basaltic pillow lavas, hyaloclastites, and breccias (A), a sheeted dike swarm (B), and a basal suite of gabbro and ultramafic rocks (C) from La Palma (Canary Islands) is interpreted as a cross section through an uplifted seamount. This series has been tilted to its present orientation of 50°/230° (plunge and azimuth), probably by upwarping due to intrusions in the central portion of the island. The basal plutonic complex (C) also includes intrusives coeval with up to 2000 m of younger subaerial alkali basaltic lavas unconformably overlying the submarine series. The plutonic suite (C) is overlain abruptly by more than 1800 m of sills (B), 0.4-1 m thick on average, with minor screens of lavas and breccias. Extrusives (A) form a 1750 m thick sequence of pillow lavas, breccias, and hyaloclastites. The clastic rocks increase in abundance upward and are of four main types: (1) breccias, consisting of partly broken pillows, formed nearly in situ, (2) heterolithologic pillow fragment breccias, (3) hyaloclastites composed dominantly of highly vesicular lapilli and ash sized shards, the latter thought to have formed by near surface explosive eruptions and been subsequently transported downslope by mass flows, (2) and (3) being interpreted to have been resedimented, and (4) pillow scoria breccias from the upper 700 m of the extrusive section consisting of amoeboidal, highly vesicular "pillows" and lava stringers and local bombs, probably formed by cracking and "bleeding" of gas-rich expanding pillow lava and some shallow submarine/subaerial lava fountaining. The extrusive series is chemically and mineralogically crudely zoned, with the most differentiated rocks (metatrachytes and mugearites) at the base and most picritic lavas occurring near the top of the series. Subsequent to emplacement, the entire extrusive and intrusive series has been hydrothermally altered, the lower part to greenschist and the upper part to smectite—zeolite facies mineral assemblages. The La Palma succession, combined with evidence from surface studies of seamounts, suggests that seamounts are formed by intrusive and extrusive processes in approximately equal portions. The nature of eruptive clastic and depositional mechanisms changes drastically during growth of a seamount if the critical depth for major magmatic degassing is surpassed and especially if magmatic explosive processes can occur at very shallow water depth, the critical depth depending on magma and thus volatile composition. Changes in slopes of a seamount influence depositional processes. Based on these factors, at least three major depositional sites develop as a seamount grows: summit, flank, and apron facies. Nonexplosive, extrusive processes prevail in the Deep Water Stage, dominantly producing pillow lavas (75%). These consist of individual pillow volcanoes up to 200 m high, with large pillows near the base and decreasing pillow size toward the top of a volcano. Pillow breccias, and pillow fragment breccias comprise approximately 20% of this facies. The deep water flank and apron facies are characterized by debris flow deposits with possibjy rather dense matrix material. The Shallow Water (shoaling) Stage is reached when the seamount top reaches the critical depth for drastic increase in exsolution of magmatic volatiles, about 800 m for the alkali basaltic seamount of La Palma, resulting in formation of mainly clastic rocks (70%): in situ pillow rind breccias and scoriaceous amoeboidal breccias and pillows are formed in the summit regions of the seamount, by repeated expansion and leaking of frothy pillow lava possibly by lava fountaining. Resedimented, heterolithologic pillow fragment breccias, lapilli breccias, and hyaloclastites are deposited on the flanks and aprons of the seamount. Pillow lavas comprise < 30% of these deposits.

Hydrologic properties and ground-water flow systems of the Paleozoic rocks in the upper Colorado River basin in Arizona, Colorado, New Mexico, Utah, and Wyoming, excluding the San Juan Basin

USGS Publications Warehouse

Geldon, Arthur L.

2003-01-01

The hydrologic properties and ground-water flow systems of Paleozoic sedimentary rocks in the Upper Colorado River Basin were investigated under the Regional Aquifer-System Analysis (RASA) program of the U.S. Geological Survey in anticipation of the development of water supplies from bedrock aquifers to fulfill the region's growing water demands. The study area, in parts of Arizona, Colorado, New Mexico, Utah, and Wyoming, covers about 100,000 square miles. It includes parts of four physiographic provinces--the Middle Rocky Mountains, Wyoming Basin, Southern Rocky Mountains, and Colorado Plateaus. A variety of landforms, including mountains, plateaus, mesas, cuestas, plains, badlands, and canyons, are present. Altitudes range from 3,100 to 14,500 feet. Precipitation is distributed orographically and ranges from less than 6 inches per year at lower altitudes to more than 60 inches per year in some mountainous areas. Most of the infrequent precipitation at altitudes of less than 6,000 feet is consumed by evapotranspiration. The Colorado and Green Rivers are the principal streams: the 1964-82 average discharge of the Colorado River where it leaves the Upper Colorado River Basin is 12,170 cubic feet per second (a decrease of 5,680 cubic feet per second since construction of Glen Canyon Dam in 1963). On the basis of their predominant lithologic and hydrologic properties, the Paleozoic rocks are classified into four aquifers and three confining units. The Flathead aquifer, Gros Ventre confining unit, Bighorn aquifer, Elbert-Parting confining unit, and Madison aquifer (Redwall-Leadville and Darwin-Humbug zones) make up the Four Corners aquifer system. A thick sequence, composed mostly of Mississippian and Pennsylvanian shale, anhydrite, halite, and carbonate rocks--the Four Corners confining unit (Belden-Molas and Paradox-Eagle Valley subunits)--overlies the Four Corners aquifer system in most areas and inhibits vertical ground-water flow between the Four Corners aquifer system and the overlying Canyonlands aquifer. Composed of the uppermost Paleozoic rocks, the Canyonlands aquifer consists, in ascending order, of the Cutler-Maroon, Weber-De Chelly, and Park City-State Bridge zones. The Paleozoic rocks are underlain by a basal confining unit consisting of Precambrian sedimentary, igneous, and metamorphic rocks and overlain throughout most of the Upper Colorado River Basin by the Chinle-Moenkopi confining unit, which consists of Triassic formations composed mostly of shale. The largest values of porosity, permeability, hydraulic conductivity, transmissivity, and artesian yield are exhibited by the Redwall-Leadville zone of the Madison aquifer and the Weber-De Chelly zone of the Canyonlands aquifer. The former consists almost entirely of Devonian and Mississippian carbonate rocks: the latter consists mostly of Pennsylvanian and Permian quartz sandstone. Unit-averaged porosity in hydrogeologic units composed of Paleozoic rocks ranges from less than 1 to 28 percent. Permeability ranges from less than 0.0001 to 3,460 millidarcies. Unit-averaged hydraulic conductivity ranges from 0.000005 to 200 feet per day. The composite transmissivity of Paleozoic rocks ranges from 0.0005 to 47,000 feet squared per day. Artesian yields to wells and springs (excluding atypical springflows) from these hydrogeologic units range from less than 1 to 10,000 gallons per minute. The permeability and watersupply capabilities of all hydrogeologic units progressively decrease from uplifted areas to structural basins. Recharge to the Paleozoic rocks is provided by direct infiltration of precipitation, leakage from streams, and ground-water inflows from structurally continuous areas west and north of the Upper Colorado River Basin. The total recharge available flom ground-water systems in the basin from direct precipitation and stream leakage is estimated to be 6,600,000 acre-feet per year. However, little of this recharge directly enters the Paleozoic rocks

Geohydrology of the lower Apalachicola-Chattahoochee-Flint River basin, southwestern Georgia, northwestern Florida, and southeastern Alabama

USGS Publications Warehouse

Torak, Lynn J.; Painter, Jaime A.

2006-01-01

The lower Apalachicola-Chattahoochee-Flint (ACF) River Basin contains about 4,600 square miles of karstic and fluvial plains and nearly 100,000 cubic miles of predominantly karst limestone connected hydraulically to the principal rivers and lakes in the Coastal Plain of southwestern Georgia, northwestern Florida, and southwestern Alabama. Sediments of late-middle Eocene to Holocene in hydraulic connection with lakes, streams, and land surface comprise the surficial aquifer system, upper semiconfining unit, Upper Floridan aquifer, and lower semiconfining unit and contribute to the exchange of ground water and surface water in the stream-lake-aquifer flow system. Karst processes, hydraulic properties, and stratigraphic relations limit ground-water and surface-water interaction to the following hydrologic units of the stream-lake-aquifer flow system: the surficial aquifer system, upper semiconfining unit, Upper Floridan aquifer, and lower confining unit. Geologic units corresponding to these hydrologic units are, in ascending order: Lisbon Formation; Clinchfield Sand; Ocala, Marianna, Suwannee, and Tampa Limestones; Hawthorn Group; undifferentiated overburden (residuum); and terrace and undifferentiated (surficial) deposits. Similarities in hydraulic properties and direct or indirect interaction with surface water allow grouping sediments within these geologic units into the aforementioned hydrologic units, which transcend time-stratigraphic classifications and define the geohydrologic framework for the lower ACF River Basin. The low water-transmitting properties of the lower confining unit, principally the Lisbon Formation, allow it to act as a nearly impermeable base to the stream-lake-aquifer flow system. Hydraulic connection of the surficial aquifer system with surface water and the Upper Floridan aquifer is direct where sandy deposits overlie the limestone, or indirect where fluvial deposits overlie clayey limestone residuum. The water level in perched zones within the surficial aquifer system fluctuates independently of water-level changes in the underlying aquifer, adjacent streams, or lakes. Where the surficial aquifer system is connected with surface water and the Upper Floridan aquifer, water-table fluctuations parallel those in adjacent streams or the underlying aquifer. More...

The Westphalian D fossil lepidodendrid forest at Table Head, Sydney Basin, Nova Scotia: Sedimentology, paleoecology and floral response to changing edaphic conditions

USGS Publications Warehouse

Calder, J.H.; Gibling, M.R.; Eble, C.F.; Scott, A.C.; MacNeil, D.J.

1996-01-01

Strata of Westphalian D age on the western coast of the Sydney Basin expose a fossil forest of approximately 30 lepidodendrid trees within one of several clastic splits of the Harbour Seam. A mutidisciplinary approach was employed to interpret the origins of the coal bed, the depositional history of the site and the response of the fossil forest to changing edaphic conditions. The megaspore and miospore records indicate that the mire vegetation was dominated by arboreous lycopsids, especially Paralycopodites, with subdominant tree ferns. Petrographic, palynological and geochemical evidence suggest that the Harbour coal bed at Table Head originated as a rheotrophic (cf. planar) mire (eutric histosol). The mire forest is interpreted to have been engulfed by prograding distributary-channel sediments; sparse protist assemblages are suggestive of a freshwater delta-plain lake environment occasionally in contact with brackish waters. Lepidodendrids persisted as site colonizers of clastic substrates even after burial of the rheotrophic peatland and influenced the morphology of deposited sediment, but apparently were unable to colonize distributary channels. Equivocal taxonomic data (compression fossils) show the fossil forest to have been composed of both monocarpic (Lepidodendron) and polycarpic (Diaphorodendron, Paralycopodites, ?Sigillaria) lycopsids, genera recorded in the palynology of the uppermost ply of the underlying coal bed. Comparatively rare within the clastic beds of the fossil forest, however, is the stem compression of Paralycopodites, whose dispersed megapores and miospores dominate the underlying coal bed. Tree diameter data recorded equivalent to breast height indicate a forest of mixed age. These data would appear to suggest that some lepidodendrids employing a polycarpic reproductive strategy were better able to cross the ecological barrier imposed between peat and clastic substrates. Foliar compressions indicate that an understory or stand of Psaronius type tree ferns co-existed with the lepidodendrids on clastic substrates, which developed as incipient gleysol soils. The entombment of the forest can be ascribed to its distributary coastal setting, local subsidence and a seasonal climate that fostered wildfire and increased sedimentation.

Geological history of the west Libyan offshore and adjoining regions

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

Benniran, M.M.; Taleb, T.M.; McCrossan, R.G.

1988-08-01

The continental margin of the African plate north of Libya is separated from the Saharan platform to the south by a major Variscan fault system running along the coastline. The structural evolution of three sedimentary basins within the margin is discussed. The Jeffara basin, onshore western Libya-southern Tunisia, formed as a right-lateral pull-part late in the Variscan event. When the strike-slip motion ceased in the Late Permian, the basin continued to subside thermally. The Sabratah (Tripolitanian) basin, offshore western Libya-southern Tunisia, and the Benghazi basin in the Sirte rise were both formed as left-lateral pull-aparts in the Late Triassic-Early Jurassic.more » From the Middle Jurassic to the present they have subsided thermally. Onshore the lower Mesozoic is characterized by continental and nearshore clastics, separated by an evaporite sequence of Late Triassic-Early Jurassic age. Offshore this sequence is thought to grade northward into open marine carbonates. Uplift along the edge of the Saharan platform during the Early Cretaceous sourced coarse clastics, which grade northward into a thick sequence of shallow-water carbonates. Throughout the Late Cretaceous and early Tertiary, high-energy carbonates were deposited around the flanks of the Sabratah basin, grading into deeper-water, fine-grained clastics and carbonates toward the center of the basin. The late Tertiary succession is dominated by clastics derived from the growing Tellian Atlas to the northwest. During the Mesozoic and Tertiary a thick sequence of carbonates was deposited on the Pelagian platform to the north of the Sabratah basin. Periodically the platform was exposed subaerially.« less

Vertical movement of ground water under the Merrill Field landfill, Anchorage, Alaska

USGS Publications Warehouse

Nelson, Gordon L.; Dearborn, L.L.

1982-01-01

Shallow groundwater under the Merrill Field sanitary landfill at Anchorage is polluted by leachate. Wells, including three Municipal-supply wells, obtain water from two confined aquifers 100-300 feet beneath the landfill area. Aquifer-test data and information on subsurface geology, ground-water levels, and properties of materials were used to estimate vertical gradients and vertical permeabilities under the landfill. The authors ' best estimates ' of vertical permeabilities of two confining units are 1 x 10 super -2 foot per day and 2 x 10 super -4 foot per day. Theoretical travel-time calculations indicate that minor amounts of pollutants may reach the upper confined aquifer after many tens of years, but that water of the composition of the leachate probably would not reach the aquifer for more than three centuries. The range of error in the theoretical travel-time calculations is likely to be plus or minus a factor of two or three. (USGS)

Altitudes and thicknesses of hydrogeologic units of the Ozark Plateaus aquifer system in Arkansas, Kansas, Missouri, and Oklahoma

USGS Publications Warehouse

Westerman, Drew A.; Gillip, Jonathan A.; Richards, Joseph M.; Hays, Phillip D.; Clark, Brian R.

2016-09-29

A hydrogeologic framework was constructed to represent the altitudes and thicknesses of hydrogeologic units within the Ozark Plateaus aquifer system as part of a regional groundwater-flow model supported by the U.S. Geological Survey Water Availability and Use Science Program. The Ozark Plateaus aquifer system study area is nearly 70,000 square miles and includes parts of Arkansas, Kansas, Missouri, and Oklahoma. Nine hydrogeologic units were selected for delineation within the aquifer system and include the Western Interior Plains confining system, the Springfield Plateau aquifer, the Ozark confining unit, the Ozark aquifer, which was divided into the upper, middle, and lower Ozark aquifers to better capture the spatial variation in the hydrologic properties, the St. Francois confining unit, the St. Francois aquifer, and the basement confining unit. Geophysical and well-cutting logs, along with lithologic descriptions by well drillers, were compiled and interpreted to create hydrologic altitudes for each unit. The final compiled dataset included more than 23,000 individual altitude points (excluding synthetic points) representing the nine hydrogeologic units within the Ozark Plateaus aquifer system.

Evidence and dating of mid-Cretaceous tectonic activity in the San Rafael Swell, Emery County, Utah

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

Eaton, J.G.; Kirkland, J.I.; Kauffman, E.G.

1990-04-01

Evidence of tectonic activity in the form of recycled conglomerates has been found in middle Cretaceous deposits on the western flank of the San Rafael Swell. These conglomerates, present in the upper part of the Dakota Formation and in the overlying basal Mancos Shale (Tununk Member), are separated by an earliest Turonian unconformity. The conglomerates appear to be derived from the Lower Cretaceous Buckhorn Conglomerate, or similar conglomerates, which were re-exposed by latest Cenomanian uplift. Coarse clastics provided to the nearshore facies of the Dakota Formation by coastal rivers are preserved as a coarsening upward sequence. Continued uplift eventually causedmore » a local marine regression by temporarily inhibiting the initial (latest Cenomanian) transgression of the Greenhorn Sea. In subaerially exposed environments pebbles and cobbles from the Buckhorn were distributed across the coastal floodplain by rivers. These clasts were reworked into a basal lag deposit when renewed transgression of the Greenhorn Sea occurred during the late early Turonian.« less

Geology of the offshore Southeast Georgia Embayment, U.S. Atlantic continental margin, based on multichannel seismic reflection profiles

USGS Publications Warehouse

Buffler, Richard T.; Watkins, Joel S.; Dillon, William P.

1979-01-01

The sedimentary section is divided into three major seismic intervals. The intervals are separated by unconformities and can be mapped regionally. The oldest interval ranges in age from Early Cretaceous through middle Late Cretaceous, although it may contain Jurassic rocks where it thickens beneath the Blake Plateau. It probably consists of continental to nearshore clastic rocks where it onlaps basement and grades seaward to a restricted carbonate platform facies (dolomite-evaporite). The middle interval (Upper Cretaceous) is characterized by prograding clinoforms interpreted as open marine slope deposits. This interval represents a Late Cretaceous shift of the carbonate shelf margin from the Blake Escarpment shoreward to about its present location, probably due to a combination of co tinued subsidence, an overall Late Cretaceous rise in sea level, and strong currents across the Blake Plateau. The youngest (Cenozoic) interval represents a continued seaward progradation of the continental shelf and slope. Cenozoic sedimentation on the Blake Plateau was much abbreviated owing mainly to strong currents.

Provenance and petrofacies, Upper Devonian sandstones, Philip Smith Mountains and Arctic quandrangles, Brooks Range, Alaska: Final report, Project No. 3

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

Anderson, A.V.; Coney, P.J.

1987-11-01

Late Devonian sandstone beds are exposed as allochthonous sequences that extend for over 1000 km along the east-west strike of the Brooks Range in northern Alaska. These horizons, at least in part, record Late Devonian tectonism and deposition along the southern margin of the Arctic Alaska block. This study identifies clastic petrofacies in the western Philip Smith Mountains and southern Arctic quadrangles and infers the composition of the source terrane. The paleogeography is not known and the original distribution of lithofacies is uncertain, owing to the extensive post-depositional tectonism. In the study area the sandstones are exposed along rugged mountainmore » tops and high ridges. Although exposures are excellent, access is often difficult. Samples were collected from exposures near the western end of the Chandalar Shelf, Atigun Pass, and the Atigun River valley in the Philip Smith Mountains quadrangle and from the Crow Nest Creek and Ottertail Creek areas in the Arctic quadrangle. 34 refs., 17 figs.« less

Environmental Controls on Photosynthetic Microbial Mat Distribution and Morphogenesis on a 3.42 Ga Clastic-Starved Platform

NASA Astrophysics Data System (ADS)

Tice, Michael M.

2009-12-01

All mats are preserved in the shallowest-water interval of those rocks deposited below normal wave base and above storm wave base. This interval is bounded below by a transgressive lag formed during regional flooding and above by a small condensed section that marks a local relative sea-level maximum. Restriction of all mat morphotypes to the shallowest interval of the storm-active layer in the BRC ocean reinforces previous interpretations that these mats were constructed primarily by photosynthetic organisms. Morphotypes α and β dominate the lower half of this interval and grew during deposition of relatively coarse detrital carbonaceous grains, while morphotype γ dominates the upper half and grew during deposition of fine detrital carbonaceous grains. The observed mat distribution suggests that either light intensity or, more likely, small variations in ambient current energy acted as a first-order control on mat morphotype distribution. These results demonstrate significant environmental control on biological morphogenetic processes independent of influences from siliciclastic sedimentation.

Rospo Mare (Adriatic Sea) - An oil-bearing paleokarst in the Mediterranean region

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

Soudet, H.; Sorriaux, P.; Michaud, F.

1990-05-01

The oil-bearing paleokarst at Rospo Mare is located in the Adriatic Sea, 20 km off the Italian coast. The reservoir lies at a depth of 1,300 m and consists of a paleokarst of Oligocene to Miocene age that developed within Cretaceous limestones, now covered by 1,200 m of Miocene-Pliocene clastics. The oil column is about 140 m. The karstic nature of the reservoir was identified through vertical cored drill holes, which allowed us to analyze the various solution features and the sedimentary infill (speleothems, terra rossa, marine clays), as well as their vertical distribution. Observations concerning the upper part ofmore » the reservoir were compared to a paleokarst of the same age, outcropping widely onshore, in quarries located nearby. Erosion morphology at the top of the karst is highly irregular, including especially paleovalleys as well as many pit-shaped sink holes. Detailed knowledge of that morphology through geophysics helped optimizing the development of the field through horizontal drilling.« less

Geology and depositional environments of the Guadalupian rocks of the northern Del Norte Mountains, West Texas

USGS Publications Warehouse

Rudine, S.F.; Wardlaw, B.R.; Rohr, D.M.; Grant, R.E.

2000-01-01

The Guadalupian rocks of the northern Del Norte Mountains were deposited in a foreland basin between land of the Marathon orogen and a carbonate shoal established on the geanticline separating the foreland basin from the Delaware basin. Deposition was alternately influenced by coarse clastic input from the orogen and carbonate shoal, which interrupted shallow basinal siltstone depletion. Relatively deeper-water deposition is characterized by carbonate input from the shoal, and relatively shallow-water deposition is characterized by sandstone input from the orogen. Deposition was in five general transgressive-regressive packages that include (1) the Road Canyon Formation and the first siltstone member and first sandstone member of the Word Formation, (2) the second siltstone member, Appel Ranch Member, and limy sandy siltstone member of the Word Formation, (3) the Vidrio Formation, (4) the lower and part of the middle members of the Altuda Formation, and (5) part of the middle and upper members of the Altuda Formation.

Apollo 16 site geology and impact melts - Implications for the geologic history of the lunar highlands

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

Spudis, P.D.

1984-11-15

The geology of the Apollo 16 site is reconsidered on the basis of data from photogeology, geochemical remote sensing, and lunar samples. The site possesses an upper surface of anorthositic gabbro and related rocks. Mafic components were deposited as basin ejecta. The events involved in its geological evolution were the Nectaris impact and the Imbrium impact. The role of large, local craters in the history of the region was to serve as topographic depressions to accumulate basin ejecta. The most abundant melt composition at Apollo 16 is an aluminous variety of LKFM basalt supplied by the Nectaris impact as ejectedmore » basin impact melt. The mafic LKFM melt may have been supplied by the Imbrium impact. More aluminous melt groups are probably derived from local, small craters. The remainder of the deposits in the region are composed of anorthositic clastic debris derived from the Nectaris basin, the local crustal substrate, and Imbrium and other basins.« less

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

Cebi, F.H.; Korkmaz, S.; Akcay, M.

The majority of coal deposits in the world are of Carboniferous and Tertiary age but Jurassic coals are seldom present. They are also exposed in northern Turkey and occur both at the lower and upper sections of the Liassic-Dogger volcanic- and volcani-clastic series. The coals at the base of the Jurassic units are characterized by higher Ba, Th, Zr, and Cr-Ni and lower S values than those at the top of the units, indicating, in general, laterally consistent trace element contents. The vertical distribution of trace elements in individual coal seams is also rather consistent. The B contents of coalsmore » from the Godul and Norsun areas vary from 1.5 to 4.3 ppm whereas those from the Alansa area are in the range of 95 to 138 ppm. This suggests that the coals in the Godul and Norsun areas were deposited in a swamp environment inundated by the sea from time to time, whereas coals of the Alansa were deposited in a saline environment.« less

Slumping and a sandbar deposit at the Cretaceous-Tertiary boundary in the El Tecolote section (northeastern Mexico): An impact-induced sediment gravity flow

NASA Astrophysics Data System (ADS)

Soria, Ana R.; Liesa, Carlos L.; Mata, Maria Pilar; Arz, José A.; Alegret, Laia; Arenillas, Ignacio; Meléndez, Alfonso

2001-03-01

Slumps affecting uppermost Méndez Formation marls, as well as the spherulitic layer and basal part of the sandy deposits of the Cretaceous-Tertiary (K-T) boundary clastic unit, are described at the new K-T El Tecolote section (northeastern Mexico). These K-T clastic deposits represent sedimentation at middle-bathyal water depths in channel and nonchannel or levee areas of reworked materials coming from environments ranging from outer shelf to shallower slope via a unidirectional, high- to low-density turbidite flow. We emphasize the development and accretion of a lateral bar in a channel area from a surging low-density turbidity current and under a high-flow regime. The slumps discovered on land and the sedimentary processes of the K-T clastic unit reflect destabilization and collapse of the continental margin, support the mechanism of gravity flows in the deep sea, and represent important and extensive evidence for the impact effects in the Gulf of México triggered by the Chicxulub event.

Pre-lithification tectonic foliation development in a clastic sedimentary sequence

NASA Astrophysics Data System (ADS)

Meere, Patrick; Mulchrone, Kieran; McCarthy, David; Timmermann, Martin; Dewey, John

2016-04-01

The current view regarding the timing of regionally developed penetrative tectonic fabrics in sedimentary rocks is that their development postdates lithification of those rocks. In this case fabric development is achieved by a number of deformation mechanisms including grain rigid body rotation, crystal-plastic deformation and pressure solution (wet diffusion). The latter is believed to be the primary mechanism responsible for shortening and the domainal structure of cleavage development commonly observed in low grade metamorphic rocks. In this study we combine field observations with strain analysis and modelling to fully characterise considerable (>50%) mid-Devonian Acadian crustal shortening in a Devonian clastic sedimentary sequence from south west Ireland. Despite these high levels of shortening and associated penetrative tectonic fabric there is a marked absence of the expected domainal cleavage structure and intra-clast deformation, which are expected with this level of deformation. In contrast to the expected deformation processes associated with conventional cleavage development, fabrics in these rocks are a product of translation, rigid body rotation and repacking of extra-formational clasts during deformation of an un-lithified clastic sedimentary sequence.

Bear-inflicted injuries - a report from Nepal.

PubMed

Atreya, Alok; Kanchan, Tanuj; Nepal, Samata; Acharya, Jenash

2016-06-01

Upper Mustang in the Northern Himalayan range of Nepal is the home of brown bears (Ursusarctos). Low-plant biomass as a result of scanty rainfall in Upper Mustang is a reason for habitat overlap of humans and wild animals. Humans who enter into the wild to collect firewood and graze cattle are liable to wild animal attacks. Such attacks, especially by brown bears, are readily identified by the type of injuries. These are more commonly confined to head and neck regions. Cutting, gnawing and tearing by sharp teeth and claws produces specific pattern of injuries, which are devastating but seldom fatal. This article reports a rare case of brown bear injury inflicted upon a man from the Upper Mustang region in Nepal. © The Author(s) 2016.

Pore-Water Quality in the Clay-Silt Confining Units of the Lower Miocene Kirkwood Formation and Hypothetical Effects on Water Quality in the Atlantic City 800-Foot Sand, Northeastern Cape May County, New Jersey, 2001

USGS Publications Warehouse

Szabo, Zoltan; Keller, Elizabeth A.; Defawe, Rose M.

2006-01-01

Pore water was extracted from clay-silt core samples collected from a borehole at Ocean View, west of Sea Isle City, in northeastern Cape May County, New Jersey. The borehole intersects the lower Miocene Kirkwood Formation, which includes a thick sand and gravel unit between two clay-silt units. The sand and gravel unit forms a major confined aquifer in the region, known as the Atlantic City 800-foot sand, the major source of potable water along the Atlantic Coast of southern New Jersey. The pore water from the core is of interest because the borehole intersects the aquifer in an area where the ground water is sodium-rich and sulfidic. Locally in the aquifer in central and southern Cape May County, sodium concentrations are near the New Jersey secondary drinking-water standard of 50 mg/L (milligrams per liter), and typically are greater than 30 mg/L, but chloride and sulfate do not approach their respective secondary drinking-water standards except in southernmost Cape May County. Pore waters from the confining units are suspected to be a source of sodium, sulfur, and chloride to the aquifer. Constituent concentrations in filtered pore-water samples were determined using the inductively coupled plasma-mass spectrometry analytical technique to facilitate the determination of low-level concentrations of many trace constituents. Calcium-sodium-sulfate-bicarbonate, calcium-chloride-sulfate, calcium-sulfate, and sodium-sulfate-chloride-bicarbonate type waters characterize samples from the deepest part of the confining unit directly overlying the aquifer (termed the 'lower' confining unit). A sodium-chloride-sulfate type water is dominant in the composite confining unit below the aquifer. Sodium, chloride, and sulfate became increasingly dominant with depth. Pore water from the deepest sample recovered (1,390 ft (feet) below land surface) was brackish, with concentrations of sodium, chloride, and sulfate of 5,930, 8,400, and 5,070 mg/L, respectively. Pore-water samples from 900 ft or less below land surface, although mineralized, were fresh, not brackish. Sodium concentrations ranged from 51.3 to 513 mg/L, with the maximum concentration found at 882 ft below land surface in the composite confining unit below the aquifer. Chloride concentrations ranged from 46.4 to 757 mg/L, with the maximum concentration found at 596 ft below land surface in the 'lower' confining unit, and were higher than those in pore water from the same units at Atlantic City, N.J. Concentrations of chloride in the composite confining unit below the aquifer were consistently greater than 250 mg/L, indicating that the confining unit can be a source of chloride at depth. Of the major anions, sulfate was the constituent whose concentration varied most, ranging from 42 to 799 mg/L. The maximum concentration was found at 406 ft below land surface, in the upper part of the confining unit overlying the aquifer and the Rio Grande water-bearing zone (termed the 'upper' confining unit). Sulfide was not detected in any pore-water sample despite the presence of abundant quantities of sulfate and sulfide in the aquifer. The absence of sulfide in the pore waters is consistent with the hypothesis that sulfate is reduced in the aquifer. The presence of arsenic, at concentrations ranging from 0.0062 to 0.0374 mg/L, is consistent with the absence of sulfide and the possible presence of iron in the pore water.

Chloride Concentration in Water from the Upper Permeable Zone of the Tertiary Limestone Aquifer System, Southeastern United States

USGS Publications Warehouse

Sprinkle, Craig L.

1982-01-01

INTRODUCTION The tertiary limestone aquifer system of the southeastern United States is a sequence of carbonate rocks referred to as the Floridan aquifer in Florida and the principal artesian aquifer in Georgia, Alabama, and South Carolina. More than 3 billion gallons of water are pumped daily from the limestone aquifer; and the system is the principal source of municipal, industrial, and agricultural water supply in south Georgia and most of Florida. The aquifer system includes units of Paleocene to early Miocene age that combine to form a continuous carbonate sequence that is hydraulically connected in varying degrees. In a small area near Brunswick, Ga., a thin sequence of rocks of Late Cretaceous age is part of the system. In and directly downdip from much of the outcrop area, the system consists of one continuous permeable unit. Further downdip the aquifer system generally consists of two major permeable zones separated by a less-permeable unit of highly variable hydraulic properties (very leaky to virtually nonleaky). Conditions for the system vary from unconfined to confined depending upon whether the argillaceous Miocene and younger rocks that form the upper confining unit have been removed by erosion. This report is one of a series of preliminary products depicting the hydrogeologic framework, water chemistry, and hydrology of the aquifer system. The map shows the distribution of chloride ions in water from the upper permeable zone of the limestone aquifer system. The upper permeable zone consists of several formations, primarily the Tampa, Suwannee, Ocala, and Avon Park Limestones (Miller 1981a, b). Chloride concentrations of water within the upper permeable zone vary from nearly zero in recharge areas to many thousands of milligrams per liter (mg/L) in coastal discharge areas. Where the aquifer system discharges into the sea, the upper permeable zone contains increasing amounts of seawater. In these areas, wells that fully penetrate the upper permeable zone will yield water with chloride concentrations that approach that of seawater, about 19500 mg/L.

Critical elements in sediment-hosted deposits (clastic-dominated Zn-Pb-Ag, Mississippi Valley-type Zn-Pb, sedimentary rock-hosted Stratiform Cu, and carbonate-hosted Polymetallic Deposits): A review: Chapter 12

USGS Publications Warehouse

Marsh, Erin; Hitzman, Murray W.; Leach, David L.

2016-01-01

Some sediment-hosted base metal deposits, specifically the clastic-dominated (CD) Zn-Pb deposits, carbonate-hosted Mississippi Valley-type (MVT) deposits, sedimentary-rock hosted stratiform copper deposits, and carbonate-hosted polymetallic (“Kipushi type”) deposits, are or have been important sources of critical elements including Co, Ga, Ge, and Re. The generally poor data concerning trace element concentrations in these types of sediment-hosted ores suggest that there may be economically important concentrations of critical elements yet to be recognized.

Holocene fluctuations of Quelccaya Ice Cap, Peru based on lacustrine and surficial geologic archives

NASA Astrophysics Data System (ADS)

Stroup, J. S.; Kelly, M. A.; Lowell, T. V.; Beal, S. A.; Smith, C. A.

2013-12-01

Peru's Quelccaya Ice Cap (QIC; 13.9°S, 70.8°W, ~5200-5670 m asl) is an important site for understanding tropical paleoclimate, mainly because of annually layered ice cores that provide an ~1800 year long record of tropical paleoclimatic conditions (e.g., Thompson et al., 2013). Here, we present a detailed record of QIC fluctuations using surficial deposits and lake sediments that extend back to late glacial time. We compare the late Holocene records of QIC 10Be-dated moraines and ice core data with lake sediments from a nearby glacially fed lake to establish the framework we use to interpret a Holocene long sediment record from a glacially fed lake. We also examine sediments from a nearby non-glacial lake to constrain non-glacial clastic input. We collected two ~5 m-long sediment cores, one from Laguna Challpacocha, which is currently fed by QIC meltwater, and one from the Laguna Yanacocha, which has not received QIC meltwater since ~12.3 ka. Changes in magnetic susceptibility, loss on ignition, bulk density and X-ray fluorescence chemistry combined with 14C and 210Pb chronologies provide information about sediment transported to the lakes. Retreat from the late Holocene extent defined by the 10Be-dated moraine record (~0.52 ka) is contemporaneous with a sharp transition from organic to clastic sedimentation in the Challpacocha core at ~ 0.52 ka. This implies that glacially-sourced clastic sedimentation, as tracked by loss on ignition, Ti counts and bulk density, increased during ice cap recession. Based on these same proxy data, we suggest the following Holocene history of QIC: QIC receded from the Challpacocha basin by ~10.6 ka. Increased clastic sedimentation at 8.2 - 4.1, 3.6 - 2.7 ka and from 0.55 ka - present are interpreted as times of ice cap recession. The increased clastic sedimentation at ~8.2 - 4.1 ka is consistent with surficial deposits near the present-day ice margin that indicate that at ~7.0 - 4.6 ka QIC was smaller than at present (Buffen et al., 2009). Clastic sedimentation may reflect the glacier thermal regime. Relic plants now being uncovered by the receding QIC (Thompson et al., 2006, 2013) suggest advance of cold-based ice that did not produce significant meltwater or rock flour. Striations, also present on the landscape, indicate warm-based ice conditions, which would produce meltwater and rock flour. We suggest that these striations were likely produced during ice cap retreat. A small QIC during early and middle Holocene time and large QIC during late Holocene time is similar to the Holocene extents of many Northern Hemisphere glaciers and apparently follows the pattern of Northern Hemisphere summer insolation.

Terahertz quantum cascade lasers based on resonant phonon scattering for depopulation.

PubMed

Hu, Qing; Williams, Benjamin S; Kumar, Sushil; Callebaut, Hans; Reno, John L

2004-02-15

We report our development of terahertz (THz) quantum cascade lasers (QCLs), in which the depopulation of the lower radiative level is achieved through resonant longitudinal optical (LO) phonon scattering. This depopulation mechanism, similar to that implemented in all the QCLs operating at mid-infrared frequencies, is robust at high temperatures and high injection levels. The unique feature of resonant LO-phonon scattering in our THz QCL structures allows a highly selective depopulation of the lower radiative level with a sub-picosecond lifetime, while maintaining a relatively long upper level lifetime (more than 5 ps) that is due to upper-to-ground-state scattering. The first QCL based on this mechanism achieved lasing at 3.4 THz (lambda approximately 87 microm) up to 87 K for pulsed operations, with peak power levels exceeding 10 mW at ca. 40 K. Using a novel double-sided metal waveguide for mode confinement, which yields a unity mode confinement factor and therefore a low total cavity loss at THz frequencies, we have also achieved lasing at wavelengths longer than 100 microm.

Folded fabric tunes rock deformation and failure mode in the upper crust.

PubMed

Agliardi, F; Dobbs, M R; Zanchetta, S; Vinciguerra, S

2017-11-10

The micro-mechanisms of brittle failure affect the bulk mechanical behaviour and permeability of crustal rocks. In low-porosity crystalline rocks, these mechanisms are related to mineralogy and fabric anisotropy, while confining pressure, temperature and strain rates regulate the transition from brittle to ductile behaviour. However, the effects of folded anisotropic fabrics, widespread in orogenic settings, on the mechanical behaviour of crustal rocks are largely unknown. Here we explore the deformation and failure behaviour of a representative folded gneiss, by combining the results of triaxial deformation experiments carried out while monitoring microseismicity with microstructural and damage proxies analyses. We show that folded crystalline rocks in upper crustal conditions exhibit dramatic strength heterogeneity and contrasting failure modes at identical confining pressure and room temperature, depending on the geometrical relationships between stress and two different anisotropies associated to the folded rock fabric. These anisotropies modulate the competition among quartz- and mica-dominated microscopic damage processes, resulting in transitional brittle to semi-brittle modes under P and T much lower than expected. This has significant implications on scales relevant to seismicity, energy resources, engineering applications and geohazards.

Hydrocarbon potential of Upper Devonian black shale, eastern Kentucky

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

Johnston, I.M.; Frankie, W.T.; Moody, J.R.

The gas-producing Upper Devonian black shales of eastern Kentucky represent cycles of organic units alternating with less-organic units that were dominated by an influx of clastics from a northeastern source. This pattern of sedimentation is typical throughout the southern Appalachian basin in areas basinal to, yet still influenced by, the Catskill delta to the northwest. These black shales, which thin westward onto the Cincinnati arch, dip eastward into the Appalachian basin. To evaluate the future gas potential of Devonian shale, a data base has been compiled, consisting of specific geologic and engineering information from 5920 Devonian shale wells in Letcher,more » Knott, Floyd, Martin, and Pike Counties, Kentucky. The first successful gas completion in eastern Kentucky was drilled in Martin County in 1901. Comparison of initial open-flow potential (IP) and long-term production data for these wells demonstrates that higher IP values generally indicate wells of higher production potential. Areas of higher IP are aligned linearly, and these lineaments are interpreted to be related to fracture systems within the Devonian shale. These fractures may be basement influenced. Temperature log analyses indicate that the greatest number of natural gas shows occur in the lower Huron Member of the Ohio Shale. Using both the temperature log to indicate gas shows and the gamma-ray log to determine the producing unit is a workable method for selecting the interval for treatment.« less

Mantle transition zone structure beneath the Canadian Shield

NASA Astrophysics Data System (ADS)

Thompson, D. A.; Helffrich, G. R.; Bastow, I. D.; Kendall, J. M.; Wookey, J.; Eaton, D. W.; Snyder, D. B.

2010-12-01

The Canadian Shield is underlain by one of the deepest and most laterally extensive continental roots on the planet. Seismological constraints on the mantle structure beneath the region are presently lacking due to the paucity of stations in this remote area. Presented here is a receiver function study on transition zone structure using data from recently deployed seismic networks from the Hudson Bay region. High resolution images based on high signal-to-noise ratio data show clear arrivals from the 410 km and 660 km discontinuities, revealing remarkably little variation in transition zone structure. Transition zone thickness is close to the global average (averaging 245 km across the study area), and any deviations in Pds arrival time from reference Earth models can be readily explained by upper-mantle velocity structure. The 520 km discontinuity is not a ubiquitous feature, and is only weakly observed in localised areas. These results imply that the Laurentian root is likely confined to the upper-mantle and if any mantle downwelling exists, possibly explaining the existence of Hudson Bay, it is also confined to the upper 400 km. Any thermal perturbations at transition zone depths associated with the existence of the root, whether they be cold downwellings or elevated temperatures due to the insulating effect of the root, are thus either non-existent or below the resolution of the study.

Allogenic controls on the fluvial architecture and fossil preservation of the Upper Triassic Ischigualasto Formation, NW Argentina

NASA Astrophysics Data System (ADS)

Colombi, Carina E.; Limarino, Carlos O.; Alcober, Oscar A.

2017-12-01

The Upper Triassic Ischigualasto Formation in NW Argentina was deposited in a fluvial system during the synrift filling of the extensional Ischigualasto-Villa Unión Basin. The expansive exposures of the fluvial architecture and paleosols provide a framework to reconstruct the paleoenvironmental evolution of this basin during the Upper Triassic using continental sequence stratigraphy. The Ischigualasto Formation deposition can be divided into seven sequential sedimentary stages: the 1) Bypass stage; 2) Confined low-accommodation stage; 3) Confined high accommodation stage; 4) Unstable-accommodation stage; 5) Unconfined high-accommodation stage; 6) Unconfined low-accommodation stage; and finally, 7) Unconfined high-accommodation stage. The sedimentary evolution of the Ischigualasto Formation was driven by different allogenic controls such as rises and falls in lake levels, local tectonism, subsidence, volcanism, and climate, which also produced modifications of the equilibrium profile of the fluvial systems. All of these factors result in different accommodations in central and flank areas of the basin, which led to different architectural configurations of channels and floodplains. Allogenic processes affected not only the sequence stratigraphy of the basin but also the vertebrate and plant taphocenosis. Therefore, the sequence stratigraphy can be used not only as a predictive tool related to fossil occurrence but also to understand the taphonomic history of the basin at each temporal interval.

Surface-Water and Groundwater Interactions along the Withlacoochee River, West-Central Florida

USGS Publications Warehouse

Trommer, J.T.; Yobbi, D.K.; McBride, W.S.

2009-01-01

A study of the Withlacoochee River watershed in west-central Florida was conducted from October 2003 to March 2007 to gain a better understanding of the hydrology and surface-water and groundwater interactions along the river. The Withlacoochee River originates in the Green Swamp area in north-central Polk County and flows northerly through seven counties, emptying into the Gulf of Mexico. This study includes only the part of the watershed located between the headwaters in the Green Swamp and the U.S. Geological Survey gaging station near Holder, Florida. The Withlacoochee River within the study area is about 108 miles long and drains about 1,820 square miles. The Withlacoochee River watershed is underlain by thick sequences of carbonate rock that are covered by thin surficial deposits of unconsolidated sand and sandy clay. The clay layer is breached in many places because of the karst nature of the underlying limestone, and the degree of confinement between the Upper Florida aquifer and the surficial aquifer is highly variable throughout the watershed. The potential for movement of water from the surface or shallow deposits to deeper deposits, or from deeper deposits to the shallow deposits, exists throughout the Withlacoochee River watershed. Water levels were higher in deeper Upper Floridan aquifer wells than in shallow Upper Floridan aquifer wells or surficial aquifer wells at 11 of 19 paired or nested well sites, indicating potential for discharge to the surface-water system. Water levels were higher in shallow Upper Floridan aquifer or surficial aquifer wells than in deeper Upper Floridan aquifer wells at five other sites, indicating potential for recharge to the deeper Upper Floridan aquifer. Water levels in the surficial aquifer and Upper Floridan aquifer wells at the remaining three sites were virtually the same, indicating little or no confinement at the sites. Potentiometric-surface maps of the Upper Floridan aquifer indicate the pattern of groundwater flow in the aquifer did not vary greatly from season to season during the study. Potentiometric contours indicate groundwater discharge to the river in the vicinity of Dade City and Lake Panasoffkee. During dry periods, groundwater from the underlying Upper Floridan aquifer contributed to the flow in the river. During wet periods, streamflow had additional contributions from runoff and input from tributaries. Groundwater has a greater effect on streamflow downstream from the Dade City station than upstream from the Dade City station because confinement between surficial deposits and the Upper Floridan aquifer is greater in the Green Swamp area than in downstream areas. Estimates of streamflow gains and losses were made along the Withlacoochee River during base-flow conditions in May 2004, April 2005, and April 2006. Base flow was higher in April 2005 than in May 2004 and April 2006. Consistent net seepage gains were identified in 16 of 20 subreaches analyzed during all seepage runs. The direction of exchange was variable in the remaining four subreaches. Low specific conductance, pH, and calcium concentrations in water from the Withlacoochee River near the headwater area indicated a surface-water system not directly connected to the Upper Floridan aquifer. Downstream from the Dade City station, higher specific conductance, pH, and calcium concentrations in the river water indicated an increasing influence of groundwater, and were similar to groundwater during low-flow conditions. Strontium isotope ratios indicate groundwater originates from shallow parts of the Upper Floridan aquifer in the upper reaches of the river, and from increasingly deeper parts of the aquifer in the downstream direction. Mean annual base-flow estimates also indicate increasing groundwater discharge to the river in the downstream direction. Mean annual base flow estimated using standard hydrograph separation method assumptions ranged from about 4.7 to 5.1 inches per year

Finite-frequency wave propagation through outer rise fault zones and seismic measurements of upper mantle hydration

USGS Publications Warehouse

Miller, Nathaniel; Lizarralde, Daniel

2016-01-01

Effects of serpentine-filled fault zones on seismic wave propagation in the upper mantle at the outer rise of subduction zones are evaluated using acoustic wave propagation models. Modeled wave speeds depend on azimuth, with slowest speeds in the fault-normal direction. Propagation is fastest along faults, but, for fault widths on the order of the seismic wavelength, apparent wave speeds in this direction depend on frequency. For the 5–12 Hz Pn arrivals used in tomographic studies, joint-parallel wavefronts are slowed by joints. This delay can account for the slowing seen in tomographic images of the outer rise upper mantle. At the Middle America Trench, confining serpentine to fault zones, as opposed to a uniform distribution, reduces estimates of bulk upper mantle hydration from ~3.5 wt % to as low as 0.33 wt % H2O.

Circulation in the Chesapeake Bay entrance region: Estuary-shelf interaction

NASA Technical Reports Server (NTRS)

Boicourt, W. C.

1981-01-01

Current meters and temperature-salinity recorders confirm the assumption that the upper layers of the continental shelf waters off Chesapeake Bay can be banded in summer, such that the coastal boundary layer (consisting of the Bay outflow) and the outer shelf flow southward while the inner shelf flows to the north, driven by the prevailing southerly winds. These measurements show that the estuary itself may also be banded in its lower reaches such that the inflow is confined primarily to the deep channel, while the upper layer outflow is split into two flow maxima on either side of this channel.

Geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin

NASA Astrophysics Data System (ADS)

Vibhava, F.; Graham, W. D.; Maxwell, R. M.

2012-12-01

Streamflow at any given location and time is representative of surface and subsurface contributions from various sources. The ability to fully identify the factors controlling these contributions is key to successfully understanding the transport of contaminants through the system. In this study we developed a fully integrated 3D surface water-groundwater-land surface model, PARFLOW, to evaluate geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin in North Central Florida. In addition to traditional model evaluation criterion, such as comparing field observations to model simulated streamflow and groundwater elevations, we quantitatively evaluated the model's predictions of surface-groundwater interactions over space and time using a suite of binary end-member mixing models that were developed using observed specific conductivity differences among surface and groundwater sources throughout the domain. Analysis of model predictions showed that geologic heterogeneity exerts a strong control on both streamflow generation processes and land atmospheric fluxes in this watershed. In the upper basin, where the karst aquifer is overlain by a thick confining layer, approximately 92% of streamflow is "young" event flow, produced by near stream rainfall. Throughout the upper basin the confining layer produces a persistent high surficial water table which results in high evapotranspiration, low groundwater recharge and thus negligible "inter-event" streamflow. In the lower basin, where the karst aquifer is unconfined, deeper water tables result in less evapotranspiration. Thus, over 80% of the streamflow is "old" subsurface flow produced by diffuse infiltration through the epikarst throughout the lower basin, and all surface contributions to streamflow originate in the upper confined basin. Climatic variability provides a secondary control on surface-subsurface and land-atmosphere fluxes, producing significant seasonal and interannual variability in these processes. Spatial and temporal patterns of evapotranspiration, groundwater recharge and streamflow generation processes reveal potential hot spots and hot moments for surface and groundwater contamination in this basin.

Hydrogeologic framework and estimates of ground-water volumes in Tertiary and upper Cretaceous hydrogeologic units in the Powder River basin, Wyoming

USGS Publications Warehouse

Hinaman, Kurt

2005-01-01

The Powder River Basin in Wyoming and Montana is an important source of energy resources for the United States. Coalbed methane gas is contained in Tertiary and upper Cretaceous hydrogeologic units in the Powder River Basin. This gas is released when water pressure in coalbeds is lowered, usually by pumping ground water. Issues related to disposal and uses of by-product water from coalbed methane production have developed, in part, due to uncertainties in hydrologic properties. One hydrologic property of primary interest is the amount of water contained in Tertiary and upper Cretaceous hydrogeologic units in the Powder River Basin. The U.S. Geological Survey, in cooperation with the Bureau of Land Management, conducted a study to describe the hydrogeologic framework and to estimate ground-water volumes in different facies of Tertiary and upper Cretaceous hydrogeologic units in the Powder River Basin in Wyoming. A geographic information system was used to compile and utilize hydrogeologic maps, to describe the hydrogeologic framework, and to estimate the volume of ground water in Tertiary and upper Cretaceous hydrogeologic units in the Powder River structural basin in Wyoming. Maps of the altitudes of potentiometric surfaces, altitudes of the tops and bottoms of hydrogeologic units, thicknesses of hydrogeologic units, percent sand of hydrogeologic units, and outcrop boundaries for the following hydrogeologic units were used: Tongue River-Wasatch aquifer, Lebo confining unit, Tullock aquifer, Upper Hell Creek confining unit, and the Fox Hills-Lower Hell Creek aquifer. Literature porosity values of 30 percent for sand and 35 percent for non-sand facies were used to calculate the volume of total ground water in each hydrogeologic unit. Literature specific yield values of 26 percent for sand and 10 percent for non-sand facies, and literature specific storage values of 0.0001 ft-1 (1/foot) for sand facies and 0.00001 ft-1 for non-sand facies, were used to calculate a second volume of ground water for each hydrogeologic unit. Significant figure considerations limited estimates of ground-water volumes to two significant digits. A total ground-water volume of 2.0x1014 ft3 (cubic feet) was calculated using porosity values, and a total ground-water volume of 3.6x1013 ft3 was calculated using specific yield and specific storage values. These results are consistent with retention properties, which would have some of the total water being retained in the sediments. Sensitivity analysis shows that the estimates of ground-water volume are most sensitive to porosity. The estimates also are sensitive to confined thickness and saturated thickness. Better spatial information for hydrogeologic units could help refine the ground-water volume estimates.

Field guide to Cretaceous-tertiary boundary sections in northeastern Mexico

NASA Technical Reports Server (NTRS)

Keller, Gerta; Stinnesbeck, Wolfgang; Adatte, Thierry; Macleod, Norman; Lowe, Donald R.

1994-01-01

This guide was prepared for the field trip to the KT elastic sequence of northeastern Mexico, 5-8 February 1994, in conjunction with the Conference on New Developments Regarding the KT Event and Other Catastrophes in Earth History, held in Houston, Texas. The four-day excursion offers an invaluable opportunity to visit three key outcrops: Arroyo El Mimbral, La Lajilla, and El Pinon. These and other outcrops of this sequence have recently been interpreted as tsunami deposits produced by the meteorite impact event that produced the 200 to 300-km Chicxulub basin in Yucatan, and distributed ejecta around the world approximately 65 m.y. ago that today is recorded as a thin clay layer found at the K/T boundary. The impact tsunami interpretation for these rocks has not gone unchallenged, and others examining the outcrops arrive at quite different conclusions: not tsunami deposits but turbidites; not KT at all but 'upper Cretaceous.' Indeed, it is in hopes of resolving this debate through field discussion, outcrop evaluation, and sampling that led the organizers of the conference to sanction this field trip. This field guide provides participants with background information on the KT clastic sequence outcrops and is divided into two sections. The first section provides regional and logistical context for the outcrops and a description of the clastic sequence. The second section presents three representative interpretations of the outcrops by their advocates. There is clearly no way that these models can be reconciled and so two, if not all three, must be fundamentally wrong. Readers of this guide should keep in mind that many basic outcrop observations that these models are based upon remain unresolved. While great measures were taken to ensure that the information in the description section was as objective as possible, many observations are rooted in interpretations and the emphasis placed on certain observations depends to some degree upon the perspective of the author.

Detrital zircons from the Tananao metamorphic complex of Taiwan: Implications for sediment provenance and Mesozoic tectonics

NASA Astrophysics Data System (ADS)

Yui, T. F.; Maki, K.; Lan, C. Y.; Hirata, T.; Chu, H. T.; Kon, Y.; Yokoyama, T. D.; Jahn, B. M.; Ernst, W. G.

2012-05-01

Taiwan formed during the Plio-Pleistocene collision of Eurasia with the outboard Luzon arc. Its pre-Tertiary basement, the Tananao metamorphic complex, consists of the western Tailuko belt and the eastern Yuli belt. These circum-Pacific belts have been correlated with the high-temperature/low-pressure (HT/LP) Ryoke belt and the high-pressure/low-temperature (HP/LT) Sanbagawa belt of Japan, respectively. To test this correlation and to reveal the architecture and plate-tectonic history of the Tananao metamorphic basement, detrital zircons were separated from 7 metasedimentary rock samples for U-Pb dating by LA-ICPMS techniques. Results of the present study, coupled with previous data, show that (1) the Tailuko belt consists of a Late Jurassic to earliest Cretaceous accretionary complex sutured against a Permian-Early Jurassic marble ± metabasaltic terrane, invaded in the north by scattered Late Cretaceous granitic plutons; the latter as well as minor Upper Cretaceous cover strata probably formed in a circum-Pacific forearc; (2) the Yuli belt is a mid- to Late Cretaceous accretionary complex containing HP thrust sheets that were emplaced attending the Late Cenozoic Eurasian plate-Luzon arc collision; (3) these two Late Mesozoic belts are not coeval, and in part were overprinted by low-grade metamorphism during the Plio-Pleistocene collision; (4) accreted clastic sediments of the Tailuko belt contain mainly Phanerozoic detrital zircons, indicating that terrigenous sediments were mainly sourced from western Cathaysia, whereas in contrast, clastic rocks of the Yuli accretionary complex contain a significant amount of Paleoproterozoic and distinctive Neoproterozoic zircons, probably derived from the North China craton and the Yangtze block ± eastern Cathaysia, as a result of continent uplift/exhumation after the Permo-Triassic South China-North China collision; and (5) the Late Jurassic-Late Cretaceous formation of the Tananao basement complex precludes the possibility that the early Yanshanian (Early Jurassic) granitoids in southern China represent a landward arc contemporaneous with the later, outboard Tananao accretionary event.

Early Mesozoic history and petroleum potential of formations in Wyoming and northern Utah

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

Picard, M.D.

1993-08-01

During the Triassic and Jurassic, over what is now Wyoming and northern Utah, roughly equal amounts of sediment were being deposited in continental settings-lake, stream, and eolian-and in shallow-marine or deltaic-plain settings-delta, beach, marsh, tidal flat, and shallow shelf. Clastic rocks dominate. In order of decreasing abundance, the rocks are fine-grained clastics (siltstone, claystone, mudstone), sandstone, carbonates, evaporites, and claystone- and carbonate-pebble conglomerate. Approximately four-fifths of the succession contains red beds or variegated layers-purple, maroon, lavender, olive, green. Unconformities bound Jurassic formations in Wyoming-Nugget, Gypsum Spring, Sundance, and Morrison. Unconformities also bound the continental Upper Triassic section-unnamed red bed unit,more » Jelm, Popo Agie-separating it from the underlying shallow-marine formations-Dinwoody, Red Peak, Alcova, Crow Mountain. Within the marine sequence, an unconformity occurs at the top of the Alcova and, quite likely, shorter periods of erosion took place at the top and below the base of the sandy faces that underlies the Alcova. The postulate duration of the principal unconformities totals about 18 m.y., at least one-sixth of early Mesozoic time. The bulk of the remaining 80-100 m.y. may be represented by a large number of smaller unconformities. For the lower Mesozoic, as for most stratigraphic intervals, a few beds contain the story of what has taken place during the abyss of geologic time. Like other places in the world where evaporites occur in the Triassic, the Wyoming section produces little crude oil. No significant sequence in the early Mesozoic shows source-bed characteristics. The Crow Mountain Sandstone contains the best reservoirs. The Lower( ) Jurassic Nugget Sandstone produces the most oil and gas in the thrust belt of southwestern Wyoming and northern Utah. Cretaceous claystones below the thrusts contain the source beds.« less

Rise and fall of bat population induced from immobile elements and fossil helminth eggs of bat guano deposits, Korea

NASA Astrophysics Data System (ADS)

Jun, Chang-Pyo; Lee, Seong-Joo

2014-05-01

Bat guano samples were collected from three carbonate caves located along the eastern coast of Korean Peninsula: Gossi Cave (40 cm high and 200 cm wide dome), Baegryong Cave (50 cm high and 100 cm wide dome), and Seongryu Cave (20 cm high platform). The guano deposits are rich in organic materials including undigested insect fragments, together with authigenic minerals and imported clastic sediments. The guano profiles were calculated to have been deposited 1) from 3097 to 4200 BP yrs in Gossi guano, 2) from 3650 to 7150 BP yrs in Baegryong guano, and 3) from 150 to 6000 BP yrs in Seongryu guano. Among the immobile elements identified, three immobile elements including Al2O3, SiO2, and TiO2 were detected from all the bat guano profiles. Distributional pattern of these elements throughout each guano profile also shows a close similarity. Such immobile elements are those of clastic sediments blown into the caves as dust. The amount of such immobile elements is closely related with deposition rate of the bat guano; low concentration of those elements implies rapid deposition rate while high concentration represents slow deposition rate of bat guano profiles. Basically, deposition rate of bat guano is controlled by the population density of bat lived in the cave. The amount of immobile elements of the Gossi Cave, for example, tends to increase toward top layer with a sudden decrease at the middle-upper layer (4,000 BP yr). It is, thus be concluded that bat population experienced fluctuation showing an decrease from 6150 to 4150 BP yr and sudden increase at 4000 BP yr, followed by constant decrease to 3150 BP yr. Fossil parasite eggs were also found from the guano deposits, and the number of parasite eggs show similar trend to that of immobile elements.

Lake Sediment Records as an Indicator of Holocene Fluctuations of Quelccaya Ice Cap, Peru and Regional Climate

NASA Astrophysics Data System (ADS)

Stroup, J. S.; Kelly, M. A.; Lowell, T. V.; Beal, S. A.; Smith, C. A.; Baranes, H. E.

2012-12-01

The past fluctuations of Quelccaya Ice Cap, (QIC; 13°S, 70°W, 5200 m asl) located in the southeastern Peruvian Andes, provide a record of tropical climate since the last glacial-interglacial transition. A detailed surficial geomorphic record of past glacial extents developed over the last several decades (e.g. Mercer and Palacios 1977; Buffen et al. 2009; Kelly et al. 2012 accepted) demonstrates that QIC is a dynamic glacial system. These records show that the ice cap was larger than present and retreating by ~11,500 yr BP, and smaller than present between ~7,000 and ~4,600 yr BP. The most recent advance occurred during the late Holocene (Little Ice Age;LIA), dated with 10Be surface exposure ages (510±90 yrs (n = 8)) (Stroup et al. in prep.). This overrode earlier deposits obscuring a complete Holocene record; we aim to address the gaps in glacial chronology using the sedimentary record archived in lakes. We retrieved two sets cores (8 and 5 m-long) from Laguna Challpacocha (13.91°S, 70.86°W, 5040 m asl), a lake that currently receives meltwater from QIC. Four radiocarbon ages from the cores suggest a continuous record dating to at least ~10,500 cal. yr BP. Variations in magnetic susceptibility, percent organic and inorganic carbon, bulk density, grayscale and X-ray fluorescence chemistry indicate changes in the amount of clastic sediment deposition. We interpret clastic sediments to have been deposited from ice cap meltwater, thus indicating more extensive ice. Clastic sediments compose the top of the core from 4 to 30 cm depth, below there is a sharp transition to organic sediments radiocarbon dated to (500±30 and 550±20 cal. yr BP). The radiocarbon ages are similar to the 10Be dated (LIA) glacial position. At least three other clastic units exist in the core; dating to ~2600-4300, ~4800-7300 and older then ~10,500 cal. yr BP based on a linear age model with four radiocarbon dates. We obtained two, ~4 m long, cores from Laguna Yanacocha (13.95°S,70.87°W, 4910 m asl), a lake that has not received glacial meltwater since late glacial time. We used the clastic sediment record to determine the input from non-glacial sources, representing ambient climate. This information tests our hypothesis that increased clastic sediment is from a glacial source in the Challpacocha record. The Yanacocha cores are composed primarily of organic-rich sediment with little clastic sediment. Eight radiocarbon ages in stratigraphic order indicate a continuous sedimentation in the lake since 11,240±90 cal. yr BP. Till at the base of the core indicates likely ice recession from the basin at this time. Variations in magnetic susceptibility, percent organic and inorganic carbon, bulk density, and gray scale suggest only minor changes in sedimentation relative to those in the Challpacocha core. Our new continuous lake sediment record provides complementary data to the discontinuous records of QIC Holocene extents as marked by moraines and exposed sections (e.g. Buffen et al. 2009; Thompson et al. 2006). Our record has some similarities with the nearby lacustrine record from Laguna Pacococha, which also receives meltwater from QIC (Rodbell and Seltzer, 2000; Abbott et al., 2003).

Standardizing texture and facies codes for a process-based classification of clastic sediment and rock

USGS Publications Warehouse

Farrell, K.M.; Harris, W.B.; Mallinson, D.J.; Culver, S.J.; Riggs, S.R.; Pierson, J.; ,; Lautier, J.C.

2012-01-01

Proposed here is a universally applicable, texturally based classification of clastic sediment that is independent from composition, cementation, and geologic environment, is closely allied to process sedimentology, and applies to all compartments in the source-to-sink system. The classification is contingent on defining the term "clastic" so that it is independent from composition or origin and includes any particles or grains that are subject to erosion, transportation, and deposition. Modifications to Folk's (1980) texturally based classification that include applying new assumptions and defining a broader array of textural fields are proposed to accommodate this. The revised ternary diagrams include additional textural fields that better define poorly sorted and coarse-grained deposits, so that all end members (gravel, sand, and mud size fractions) are included in textural codes. Revised textural fields, or classes, are based on a strict adherence to volumetric estimates of percentages of gravel, sand, and mud size grain populations, which by definition must sum to 100%. The new classification ensures that descriptors are applied consistently to all end members in the ternary diagram (gravel, sand, and mud) according to several rules, and that none of the end members are ignored. These modifications provide bases for standardizing vertical displays of texture in graphic logs, lithofacies codes, and their derivatives- hydrofacies. Hydrofacies codes are nondirectional permeability indicators that predict aquifer or reservoir potential. Folk's (1980) ternary diagram for fine-grained clastic sediments (sand, silt, and clay size fractions) is also revised to preserve consistency with the revised diagram for gravel, sand, and mud. Standardizing texture ensures that the principles of process sedimentology are consistently applied to compositionally variable rock sequences, such as mixed carbonate-siliciclastic ramp settings, and the extreme ends of depositional systems.

Structure, stratigraphy, and hydrocarbons offshore southern Kalimantan, Indonesia

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

Bishop, W.F.

1980-01-01

Offshore southern Kalimantan (Borneo), Indonesia, the Sunda Shelf is bounded on the south by the east-west-trending Java-Madura foreland basin and on the north by outcrops of the granitic core of Kalimantan. Major northeast-southwest-trending faults created a basin and ridge province which controlled sedimentation at least until early Miocene time. Just above the unconformity, the oldest pre-CD Limestone clastic strata are fluviatile and lacustrine, the remainder consisting largely of shallow-marine, calcareous shale with interbeds of fine-grained, quartzose sandstone. A flood of terrigenous detritus - Kudjung unit 3 - resulted from post-CD Limestone uplift, and is more widely distributed. Unit 3 consistsmore » largely of fluviatile sandstone interbedded with shale and mudstone, grading upward to marine clastics with a few thin limestones near the top. The resulting Kudjing unit 2 is largely a shallow-basinal deposit, comprising thin, micritic limestones interbedded with calcareous shale and mudstone. Infilling of the basins was nearly complete by the end of Kudjing unit 1 deposition. Eastern equivalents of Kudjing units 1 and 2 are known as the Berai limestone interval (comprising bank, reefal, basinal, and open-marine limestones, and marl). Of the three oil fields in the area, two are shut in, but one has produced nearly 100 million bbl. Gas shows were recorded in most wells of the area, but the maximum flow was 1.8 MMcf methane/day, although larger flows with high percentages of carbon dioxide and nitrogen were reported. Fine-grained clastic strata of unit 3 are continuous with those farther south, where geochemical data indicate good source and hydrocarbon-generating potential. Sandstones with reservoir capability are present in the clastic intervals, and several carbonate facies have sporadically developed porosity. A variety of structural and stratigraphic traps is present. 20 figures, 1 table.« less

Diatremes of the Hopi Buttes, Arizona; chemical and statistical analyses

USGS Publications Warehouse

Wenrich, K.J.; Mascarenas, J.F.

1982-01-01

Lacustrine sediments deposited in maar lakes of the Hopi Buttes diatremes are hosts for uranium mineralization of as much as 1500 ppm. The monchiquites and limburgite turfs erupted from the diatremes are distinguished from normal alkalic basalts of the Colorado Plateau by their extreme silica undersaturation and high water, TiO2, and P2O5 contents. Many trace elements are also unusually abundant, including Ag, As, Ba, Be, Ce, Dy, Eu, F, Gd, Hf, La, Nd, Pb, Rb, Se, Sm, Sn, Sr, Ta, Tb, Th, U, V, Zn, and Zr. The lacustrine sediments, which consist predominantly of travertine and clastic rocks, are the hosts for syngenetic and epigenetic uranium mineralization of as much as 1500 ppm uranium. Fission track maps show the uranium to be disseminated within the travertine and clastic rocks, and although microprobe analyses have not, as yet, revealed discrete uranium-bearing phases, the clastic rocks show a correlation of high Fe, Ti, and P with areas of high U. Correlation coefficients show that for the travertines, clastics, and limburgite ruffs, Mo, As, Sr, Co, and V appear to have the most consistent and strongest correlations with uranium. Many elements, including many of the rare-earth elements, that are high in these three rocks are also high in the monchiquites, as compared to the average crustal abundance for the respective rock type. This similar suite of anomalous elements, which includes such immobile elements as the rare earths, suggests that Fluids which deposited the travertines were related to the monchiquitic magma. The similar age of about 5 m.y. for both the lake beds and the monchiquites also appears to support this source for the mineralizing fluids.

Using Geophysics to Define Hydrostratigraphic Units in the Edwards and Trinity Aquifers, Texas

NASA Astrophysics Data System (ADS)

Smith, B. D.; Blome, C. D.; Clark, A. K.; Kress, W.; Smith, D. V.

2007-05-01

Airborne and ground geophysical surveys conducted in Uvalde, Medina, and northern Bexar counties, Texas, can be used to define and characterize hydrostratigraphic units of the Edwards and Trinity aquifers. Airborne magnetic surveys have defined numerous Cretaceous intrusive stocks and laccoliths, mainly in Uvalde County, that influence local hydrology and perhaps regional ground-water flow paths. Depositional environments in the aquifers can be classified as shallow water platforms (San Marcos Platform, Edwards Group), shoal and reef facies (Devils River Trend, Devils River Formation), and deeper water basins (Maverick Basin, West Nueces, McKnight, and Salmon Peak Formations). Detailed airborne and ground electromagnetic surveys have been conducted over the Edwards aquifer catchment zone (exposed Trinity aquifer rocks), recharge zone (exposed Edwards aquifer rocks), and artesian zone (confined Edwards) in the Seco Creek area (northeast Uvalde and Medina Counties; Devils River Trend). These geophysical survey data have been used to divide the Edwards exposed within the Balcones fault zone into upper and lower hydrostratigraphic units. Although both units are high electrical resistivity, the upper unit has slightly lower resistivity than the lower unit. The Georgetown Formation, at the top of the Edwards Group has a moderate resistivity. The formations that comprise the upper confining units to the Edwards aquifer rocks have varying resistivities. The Eagleford and Del Rio Groups (mainly clays) have very low resistivities and are excellent electrical marker beds in the Seco Creek area. The Buda Limestone is characterized by high resistivities. Moderate resistivities characterize the Austin Group rocks (mainly chalk). The older Trinity aquifer, underlying the Edwards aquifer rocks, is characterized by less limestone (electrically resistive or low conductivity units) and greater quantities of mudstones (electrically conductive or low resistivity units). In the western area (Devils River Trend and Maverick Basin) of the Trinity aquifer system there are well-defined collapse units and features that are marked by moderate resistivities bracketed by resistive limestone and conductive mudstone of the Glen Rose Limestone. In the central part of the aquifer (San Marcos Platform) the Trinity's lithologies are divided into upper and lower units with further subdivisions into hydrostratigraphic units. These hydrostratigraphic units are well mapped by an airborne electromagnetic survey in Bexar County. Electrical properties of the Edwards aquifer also vary across the fresh-saline water interface where ground and borehole electrical surveys have been conducted. The saline- saturated Edwards is predictably more conductive than the fresh-water saturated rocks. Similar fresh-saline water interfaces exist within the upper confining units of the Edwards aquifer (Carrizo-Wilcox aquifer) and the Trinity aquifer rocks.

Surface-geophysical characterization of ground-water systems of the Caloosahatchee River basin, southern Florida

USGS Publications Warehouse

Cunningham, Kevin J.; Locker, Stanley D.; Hine, Albert C.; Bukry, David; Barron, John A.; Guertin, Laura A.

2001-01-01

The Caloosahatchee River Basin, located in southwestern Florida, includes about 1,200 square miles of land. The Caloosahatchee River receives water from Lake Okeechobee, runoff from the watershed, and seepage from the underlying ground-water systems; the river loses water through drainage to the Gulf of Mexico and withdrawals for public-water supply and agricultural and natural needs. Water-use demands in the Caloosahatchee River Basin have increased dramatically, and the Caloosahatchee could be further stressed if river water is used to accommodate restoration of the Everglades. Water managers and planners need to know how much water will be used within the river basin and how much water is contributed by Lake Okeechobee, runoff, and ground water. In this study, marine seismic-reflection and ground-penetrating radar techniques were used as a means to evaluate the potential for flow between the river and ground-water systems. Seven test coreholes were drilled to calibrate lithostratigraphic units, their stratal geometries, and estimated hydraulic conductivities to surface-geophysical profiles. A continuous marine seismic-reflection survey was conducted over the entire length of the Caloosahatchee River and extending into San Carlos Bay. Lithostratigraphic units that intersect the river bottom and their characteristic stratal geometries were identified. Results show that subhorizontal reflections assigned to the Tamiami Formation intersect the river bottom between Moore Haven and about 9 miles westward. Oblique and sigmoidal progradational reflections assigned to the upper Peace River Formation probably crop out at the floor of the river in the Ortona area between the western side of Lake Hicpochee and La Belle. These reflections image a regional-scale progradational deltaic depositional system containing quartz sands with low to moderate estimated hydraulic conductivities. In an approximate 6-mile length of the river between La Belle and Franklin Lock, deeper karstic collapse structures are postulated. These structures influence the geometries of parallel reflections that intersect the river channel. Here, reflections assigned to the Buckingham Limestone Member of the Tamiami Formation (a confining unit) and reflections assigned to the clastic zone of the sandstone aquifer likely crop out at the river bottom. Beneath these shallow reflections, relatively higher amplitude parallel reflections of the carbonate zone of the sandstone aquifer are well displayed in the seismic-reflection profiles. In San Carlos Bay, oblique progradational reflections assigned to the upper Peace River Formation are shown beneath the bay. Almost everywhere beneath the river, a diffuse ground-water flow system is in contact with the channel bottom. Ground-penetrating radar profiles of an area about 2 miles north of the depositional axis of the deltaic depositional system in the Ortona area show that progradational clinoforms imaged on seismic reflection profiles in the Caloosahatchee River are present within about 17 feet of the ground surface. Ground-penetrating radar profiles show southward dipping, oblique progradational reflections assigned to the upper Peace River Formation that are terminated at their tops by a toplapping or erosional discontinuity. These clinoformal reflections image clean quartz sand that is probably characterized by moderate hydraulic conductivity. This sand could be mapped using ground-penetrating radar methods.

The age of volcanic tuffs from the Upper Freshwater Molasse (North Alpine Foreland Basin) and their possible use for tephrostratigraphic correlations across Europe for the Middle Miocene

NASA Astrophysics Data System (ADS)

Rocholl, Alexander; Schaltegger, Urs; Gilg, H. Albert; Wijbrans, Jan; Böhme, Madelaine

2018-03-01

The Middle Miocene Upper Freshwater Molasse sediments represent the last cycle of clastic sedimentation during the evolution of the North Alpine Foreland Basin. They are characterized by small-scale lateral and temporal facies changes that make intra-basin stratigraphic correlations at regional scale difficult. This study provides new U-Pb zircon ages as well as revised 40Ar/39Ar data of volcanic ash horizons in the Upper Freshwater Molasse sediments from southern Germany and Switzerland. In a first and preliminary attempt, we propose their possible correlation to other European tephra deposits. The U-Pb zircon data of one Swiss (Bischofszell) and seven southern German (Zahling, Hachelstuhl, Laimering, Unterneul, Krumbad, Ponholz) tuff horizons indicate eruption ages between roughly 13.0 and 15.5 Ma. The stratigraphic position of the Unterneul and Laimering tuffs, bracketing the ejecta of the Ries impact (Brockhorizon), suggests that the Ries impact occurred between 14.93 and 15.00 Ma, thus assigning the event to the reversed chron C5Bn1r (15.032-14.870 Ma) which is in accordance with paleomagnetic evidence. We combine our data with published ages of tuff horizons from Italy, Switzerland, Bavaria, Styria, Hungary, and Romania to derive a preliminary tephrochronological scheme for the Middle Miocene in Central Europe in the age window from 13.2 to 15.5 Ma. The scheme is based on the current state of knowledge that the Carpathian-Pannonian volcanic field was the only area in the region producing explosive calc-alkaline felsic volcanism. This preliminary scheme will require verification by more high-quality ages complemented by isotopic, geochemical and paleomagnetic data.

Neogene shortening and exhumation of the Zagros fold-thrust belt and foreland basin in the Kurdistan region of northern Iraq

NASA Astrophysics Data System (ADS)

Koshnaw, Renas I.; Horton, Brian K.; Stockli, Daniel F.; Barber, Douglas E.; Tamar-Agha, Mazin Y.; Kendall, Jerome J.

2017-01-01

The Zagros fold-thrust belt in the Kurdistan region of Iraq encroached southward toward a rapidly subsiding Neogene foreland basin and was later partitioned by out-of-sequence shortening focused along the Mountain Front Flexure (MFF), as defined by new low-temperature thermochronologic, stratigraphic, and provenance results. Apatite (U-Th)/He ages document rapid deformation advance from the Main Zagros Fault to southern frontal structures (Kirkuk, Shakal, and Qamar thrusts) at 10-8 Ma, followed by potential basement-involved out-of-sequence development of the MFF (Qaradagh anticline) by 5 Ma. Distinct shifts in detrital zircon U-Pb provenance signatures for Neogene foreland basin fill provide evidence for drainage reorganization during fold-thrust belt advance. U-Pb age spectra and petrologic data from the Injana (Upper Fars) Formation indicate derivation from a variety of Eurasian, Pan-African, ophiolitic and Mesozoic-Cenozoic volcanic terranes, whereas the Mukdadiya (Lower Bakhtiari) and Bai-Hasan (Upper Bakhtiari) Formations show nearly exclusive derivation from the Paleogene Walash-Naopurdan volcanic complex near the Iraq-Iran border. Such a sharp cutoff in Eurasian, Pan-African, and ophiolitic sources is likely associated with drainage reorganization and tectonic development of the geomorphic barrier formed by the MFF. As a result of Zagros crustal shortening, thickening and loading, the Neogene foreland basin developed and accommodated an abrupt influx of fluvial clastic sediment that contains growth stratal evidence of synkinematic accumulation. The apparent out-of-sequence pattern of upper crustal shortening in the hinterland to foreland zone of Iraqi Kurdistan suggests that structural inheritance and the effects of synorogenic erosion and accumulation are important factors influencing the irregular and episodic nature of orogenic growth in the Zagros.

Sedimentological and diagenetic patterns of anhydrite deposits in the Badenian evaporite basin of the Carpathian Foredeep, southern Poland

NASA Astrophysics Data System (ADS)

Kasprzyk, Alicja

2003-05-01

Anhydrite deposits are widely distributed in the Middle Miocene Badenian evaporite basin of Poland, including the marginal sulphate platform and adjacent salt depocenter. Particular sedimentological, petrographic and geochemical characteristics of these anhydrite deposits and especially common pseudomorphic features, inherited from the precursor gypsum deposits, allow the interpretation of the original sedimentary facies. The observed facies distribution and succession (lower and upper members) reveal three distinct facies associations that record a range of depositional environments from nearshore to deeper basinal settings. Platform sulphates were deposited in subaerial and shallow-marine environments (shoreline and inner platform-lagoon system) mainly as autochthonous selenitic gypsum. This was reworked and redistributed into deeper waters (outer platform-lagoon, slope and the proximal basin floor system) to form resedimented facies composed mostly of allochthonous clastic gypsum and minor anhydrite. The general variation in petrographic and geochemical compositions of anhydrite lithofacies of the lower and upper members reflects the brine evolution, as the result of interactions between seawater, meteoric runoff and highly saline, residual pore fluids. The results indicate the importance of synsedimentary and diagenetic anhydritisation processes in formation of the Badenian anhydrite lithofacies, all of which preserve the original depositional features of the former gypsum. This also applies to the basinal anhydrite previously interpreted to have a depositional genesis. Two different genetic patterns of anhydrite have been reinforced by this study: (1) synsedimentary anhydritisation of gypsum deposits by highly concentrated brines or elevated temperatures in surficial to shallow-burial environments (lower member), and (2) successive phases (syndepositional de novo growth, early diagenetic to late diagenetic replacement of former gypsum) of anhydrite formation during progressive burial (upper member).

Lower Brioverian formations (Upper Proterozoic) of the Armorican Massif (France): geodynamic evolution of source areas revealed by sandstone petrography and geochemistry

NASA Astrophysics Data System (ADS)

Dabard, Marie Pierre

1990-11-01

Formations with interbedded cherts constitute an important part of the Lower Brioverian succession (Upper Proterozoic age) in the Armorican Massif (northwest France). These formations are composed of shale-sandstone alternations with interbedded siliceous carbonaceous members. Petrographic and geochemical study of the detrital facies shows that these rocks are compositionally immature. The wackes are rich in lithic fragments (volcanic fragments: 3-20% modal; sedimentary and metamorphic fragments: 0-7% modal) and in feldspar (5-16%). From the geochemical point of view, they are relatively enriched in Fe 2+MgO (about 5.5%) and in alkalis with {Na 2O }/{K 2O } ratios greater than 1. The CaO contents are low (about 0.3%). Slightly negative Eu anomalies are observed ( {Eu}/{Eu ∗} = 0.8 ). Their chemical compositions are in agreement with a dominantly acidic source area with deposition in a continental active margin setting. Compared with other Upper Proterozoic deposits of the Armorican Massif, the interbedded-chert formations appear rather similar to other deposits in North Brittany which accumulated in an intra-arc or back-arc basin environment. The formations with interbedded cherts are interpreted as having been deposited during an early stage of magmatic arc activity (around 640-630 Ma ago) in an immature marginal basin. The clastic supply to these formations is derived in part from early volcanic products (acidic to intermediate) which are linked to subduction beneath the North Armorican Domain. Another component is inherited from the reworking of 2000 Ma old basement relics. The opening of the back-arc domain, with associated basaltic volcanism, would bring about a progressive displacement of the interbedded-chert depositional basin towards the continental margin.

Upper crust beneath the central Illinois basin, United States

USGS Publications Warehouse

McBride, J.H.; Kolata, Dennis R.

1999-01-01

Newly available industry seismic reflection data provide critical information for understanding the structure and origin of the upper crust (0-12 km depth) beneath the central Illinois basin and the seismic-tectonic framework north of the New Madrid seismic zone in the central Mississippi Valley. Mapping of reflector sequences furnishes the first broad three-dimensional perspective of the structure of Precambrian basement beneath the central United States Midcontinent. The highly coherent basement reflectivity is expressed as a synformal wedge of dipping and subhorizontal reflections situated beneath the center of the Illinois basin that thickens and deepens to the northeast (e.g., 0 to ???5.3 km thickness along a 123 km south to north line). The thickening trend of the wedge qualitatively mimics the northward thickening of the Late Cambrian Mt. Simon Sandstone; however, other Paleozoic units in the Illinois basin generally thicken southward into the basin center. The seismic data also reveal an anomalous subsequence defined by a spoon-shaped distribution of disrupted reflections located along the southern margin of the wedge. The boundaries of this subsequence are marked by distinct steeply dipping reflections (possible thrust faults?) that continue or project up to antiformal disruptions of lower Paleozoic marker reflectors, suggesting Paleozoic or possibly later tectonic reactivation of Precambrian structure. The areal extent of the subsequence appears to roughly correspond to an anomalous concentration of larger magnitude upper to middle crustal earthquakes. There are multiple hypotheses for the origin of the Precambrian reflectivity, including basaltic flows or sills interlayered with clastic sediments and/or emplaced within felsic igneous rocks. Such explanations are analogous to nearby Keweenawan rift-related volcanism and sedimentation, which initiated during Proterozoic rifting, and were followed eventually by reverse faulting along the rift margins caused by Grenville compression.

Characteristics of a young lava-hyaloclastite sheet, Snaebylisheidi, Iceland

NASA Astrophysics Data System (ADS)

White, J. D.; Gorny, C. F.; Gudmundsson, M. T.

2009-12-01

Extensive sheets of hyaloclastite volcaniclastic debris, coupled with and intruded by largely underlying layers of coherent basalt, are common in the Sida area of southeastern Iceland. They were initially interpreted as submarine deposits, but have recently been re-interpreted as nonmarine deposits formed in the presence of glaciers. Detailed interpretation of the units has been challenging, because their source areas are not preserved. A younger deposit of the same type forms an elongate flat-topped ridge in the Snaebylisheidi area. Its volume of ca. 35 cubic km is similar to that of the larger Sida units, its source area is preserved, and parts of the deposit remain unlithified. Our initial investigation reveals that the source area is dominated by clastic deposits. There is no evidence for a source edifice of pillow or sheet lavas, but there are extensive low-level intrusions near the base, and a plexus of smaller high-level intrusions showing evidence of high viscosities during emplacement. Isolated pillows and other fluidal juvenile clasts near the source lie within matrices of highly vesicular ash and lapilli, or of mixed vesicular and dense glassy fragments. Downstream in the unit, deposits are dominated by dense clasts, and these can in places be demonstrated to have been derived locally from the underlying to intruding basalt sheet. Larger dense clasts are commonly highly irregular, vuggy, and composite; in places many are rolled into subspherical forms enclosing matrix material comprising dense angular glass fragments. The clastic part of the unit has an upper subunit dominated by well-developed bedding in complex geometries with multiple internal truncation surfaces. Lower subunits include thick structureless to alignment-bedded layers, along with intrusion-dominated zones. Soft-sediment deformation is ubiquitous along the edges of the deposit, with many layers broken and tilted to subvertical inclinations. Taken together, these features indicate that little or no lava accumulated at the source area during eruption, but that much basalt was intruded into unconsolidated volcaniclastic deposits. Coherent basalt sheets extended downslope from the source, perhaps largely as intrusions into earlier-deposited tephra, and produced much of the downstream clastic material by local fragmentation of the advancing sheet. Thick beds reflecting high accumulation rates are intercalated with groups of thinner beds formed by multiple depositional pulses. Deformation along deposit tops and edges records pervasive slumping of the unconsolidated deposits. The characteristics overall are suggestive of an initially explosive subglacial origin, with much of the unit emplaced subglacially. More work is underway to better understand the source eruption, and the way in which the basalt sheet was emplaced and associated volcaniclastic deposits produced and deposited.

Recycling of Amazonian detrital zircons in the Mixteco terrane, southern Mexico: Paleogeographic implications during Jurassic-Early Cretaceous and Paleogene times

NASA Astrophysics Data System (ADS)

Silva-Romo, Gilberto; Mendoza-Rosales, Claudia Cristina; Campos-Madrigal, Emiliano; Morales-Yáñez, Axél; de la Torre-González, Alam Israel; Nápoles-Valenzuela, Juan Ivan

2018-04-01

In the northeastern Mixteco terrane of southern Mexico, in the Ixcaquixtla-Atzumba region, the recycling of Amazonian detrital zircons records the paleogeography during the Mesozoic period in the context of the breakup of Pangea, a phenomenon that disarticulated the Sanozama-La Mora paleo-river. The clastic units of southern Mexico in the Ayuquila, Otlaltepec and Zapotitlán Mesozoic basins, as well as in the Atzumba Cenozoic basin, are characterized by detrital zircon contents with ages specific to the Amazonian craton, ranging between 3040 and 1278 Ma. The presence of zircons of Amazonian affinity suggests a provenance by recycling from carrier units such as the La Mora Formation or the Ayú Complex. In the area, the Ayú and Acatlán complexes form the Cosoltepec block, a paleogeographic element that during Early Cretaceous time acted as the divide between the slopes of the paleo-Gulf of Mexico and the paleo-Pacific Ocean. The sedimentological characteristics of the Jurassic-Cenozoic clastic successions in the Ixcaquixtla-Atzumba region denote relatively short transport in braided fluvial systems and alluvial fans. In this way, several basins are recognized around the Cosoltepec block. At the southeastern edge of the Cosoltepec block, the Ayuquila and Tecomazúchil formations accumulated in the Ayuquila continental basin on the paleo-Pacific Ocean slope. On the other hand, within the paleo-Gulf of Mexico slope, in the Otlaltepec continental basin, the Piedra Hueca and the Otlaltepec formations accumulated. The upper member of the Santa Lucía Formation accumulated in a transitional environment on the southwestern shoulder of the Zapotitlán basin, as well as on the paleo-Gulf of Mexico slope. In the Ayuquila basin, a marine transgression is recognized that advanced from south to north during the Late Jurassic. At the northeastern edge of the Cosoltepec block, we propose that the Santa Lucía formation attests to a transgression from the paleo-Gulf of Mexico during the Early Cretaceous. Thus, the Cosoltepec block flood occurred during the Albian-Cenomanian, as recognized by the Cipiapa Limestone accumulation. The subsequent uplift of the region and its incorporation into the continental slope is attested by the Atzumba Formation, which offers further evidence of the content of Amazonian detrital zircons recycled from the Ayú Complex. The Atzumba Formation accumulated as alluvial fans during the Paleogene at the hanging wall of the Chazumba fault, which displaced the Cosoltepec block. That is, the detrital zircons in the clastic successions of the Ixcaquixtla-Atzumba region bear indirect testimony to the origin and Amazonian affinity of the Ayú Complex and/or other lithodemes of the Acatlán Complex.

Tectono-sedimentary constraints to the Oligocene-to-Miocene evolution of the Peloritani thrust belt (NE Sicily)

NASA Astrophysics Data System (ADS)

Giunta, G.; Nigro, F.

1999-12-01

The Peloritani thrust belt belongs to the southern sector of the Calabrian Arc and is formed by a set of south-verging tectonic units, including crystalline basement and sedimentary cover (from the top: Aspromonte U.; Mela U.; Mandanici U.; Fondachelli U.; Longi-Taormina U.), piled up starting from Late Oligocene. At least two main terrigenous clastic formations lie with complicated relationships on top of the previous units: the Frazzanò Fm (Oligocene) and the Stilo-Capo d'Orlando Fm (Late Oligocene?-Early Miocene), as syn-to-post-tectonic deposits. These clastic deposits have different characteristics, in space and time, representing or flysch-like sequences involved in several thrust events (Frazzanò Fm) or molassic-like sequences (Stilo-Capo d'Orlando Fm), which unconformably overlie the tectonic units. In the present paper we describe a kinematic model of the progressive foreland migration of the Peloritani thrust belt, starting from Oligocene, carrying piggy-back basins and incorporating foredeep deposits, recognised in the Frazzanò-Stilo-Capo d'Orlando terrigenous successions. In general, the facies and structural observations on the overall Oligo-Miocene clastic sequences, outcropping in the Western Peloritani Mts, indicate: (a) the distal character of the Frazzanò Fm; (b) a complex group of terrigenous facies of the Stilo-Capo d'Orlando Fm, with lateral-to-vertical organisation, characterised by a distal-to-proximal-to-distal facies trend; (c) facies analogies of the basal portions of the Stilo-Capo d'Orlando Fm with the Frazzanò Fm; (d) the involvement of the Frazzanò Fm in lowermost and more external thrusting, and of the basal (Late Oligocene?) distal Stilo-Capo d'Orlando facies in the higher and inner thrusting during the early stages of deformation; (e) the involvement of the proximal Stilo-Capo d'Orlando facies in the tectonic edifice during the Early Miocene deformation; (f) the generally unconformable stratigraphical contacts of the higher proximal-to-distal (Early Miocene) Stilo-Capo d'Orlando facies on the constructing mobile belt; and (g) the presence of various thrust-faults, distinguished in a sequential order. The collected data allow us to hypothesise that the Oligo-Miocene tectono-sedimentary history was characterised by a foredeep with a deforming internal flank, probably lying in onlap on the constructing tectonic edifice (Frazzanò-lower Stilo-Capo d'Orlando Fms), and then deformed and covered by a piggy-back like sequence (middle-upper Stilo-Capo d'Orlando Fm), which was subsequently also deformed. The tectono-sedimentary evolution of the Peloritani belt has been probably developed through a progressive migration towards the foreland of a foredeep-compressional front couple and the chain body. The thrust stack progressively incorporates terrigenous foredeep deposits and in turn carried piggy-back basins.

An undergraduate student project to improve mechanical control of perenial nutsedges with a peanut digger in organic crop production

USDA-ARS?s Scientific Manuscript database

Perennial nutsedges are difficult to control in organic crop production systems. Tubers are generally confined to the upper portions of the soil profile and vulnerable to desiccation when on the soil surface. A peanut digger is a common implement found in the coastal plain region of the southeaste...

The American species of Orthophragmina and Lepidocyclina

USGS Publications Warehouse

Cushman, J.A.

1920-01-01

Orbitoid Foraminifera, on account of their short stratigraphic range, have proved to be excellent horizon markers, and, because of their wide geographic distribution, they are valuable in correlation. The genus Orbitoides, as now restricted, is found exclusively in deposits of Cretaceous age, Orthophragmina appears to be confined to the Eocene; but Lepidocyclina ranges through the upper Eocene and Oligocene.

Effects of Prescribed Fire on Herpetofauna Within Hardwood Forests of the Upper Piedmont of South Carolina: A Preliminary Analysis

Treesearch

Thomas M. Floyd; Kevin R. Russell; Christopher E. Moorman; David H. van Lear; David C. Guynn; J. Drew Lanham

2002-01-01

Despite a large body of knowledge concerning the use of prescribed burning for wildlife management, amphibians and reptiles (collectively, herpetofauna) have received relatively little attention regarding their responses to fire. With few exceptions, previous studies of herpetofauna and prescribed burning have been confined to fire-maintained, pine-dominated...

Age and tectonic setting of the Mesozoic McCoy Mountains Formation in western Arizona, USA

USGS Publications Warehouse

Spencer, J.E.; Richard, S.M.; Gehrels, G.E.; Gleason, J.D.; Dickinson, W.R.

2011-01-01

The McCoy Mountains Formation consists of Upper Jurassic to Upper Cretaceous siltstone, sandstone, and conglomerate exposed in an east-west-trending belt in southwestern Arizona and southeastern California. At least three different tectonic settings have been proposed for McCoy deposition, and multiple tectonic settings are likely over the ~80 m.y. age range of deposition. U-Pb isotopic analysis of 396 zircon sand grains from at or near the top of McCoy sections in the southern Little Harquahala, Granite Wash, New Water, and southern Plomosa Mountains, all in western Arizona, identifi ed only Jurassic or older zircons. A basaltic lava fl ow near the top of the section in the New Water Mountains yielded a U-Pb zircon date of 154.4 ?? 2.1 Ma. Geochemically similar lava fl ows and sills in the Granite Wash and southern Plomosa Mountains are inferred to be approximately the same age. We interpret these new analyses to indicate that Mesozoic clastic strata in these areas are Upper Jurassic and are broadly correlative with the lowermost McCoy Mountains Formation in the Dome Rock, McCoy, and Palen Mountains farther west. Six samples of numerous Upper Jurassic basaltic sills and lava fl ows in the McCoy Mountains Formation in the Granite Wash, New Water, and southern Plomosa Mountains yielded initial ??Nd values (at t = 150 Ma) of between +4 and +6. The geochemistry and geochronology of this igneous suite, and detrital-zircon geochronology of the sandstones, support the interpretation that the lower McCoy Mountains Formation was deposited during rifting within the western extension of the Sabinas-Chihuahua-Bisbee rift belt. Abundant 190-240 Ma zircon sand grains were derived from nearby, unidentifi ed Triassic magmatic-arc rocks in areas that were unaffected by younger Jurassic magmatism. A sandstone from the upper McCoy Mountains Formation in the Dome Rock Mountains (Arizona) yielded numerous 80-108 Ma zircon grains and almost no 190-240 Ma grains, revealing a major reorganization in sediment-dispersal pathways and/or modifi cation of source rocks that had occurred by ca. 80 Ma. ?? 2011 Geological Society of America.

Geology, hydrology, and water quality of the Tracy-Dos Palos area, San Joaquin Valley, California

USGS Publications Warehouse

Hotchkiss, W.R.; Balding, G.O.

1971-01-01

The Tracy-Dos Palos area includes about 1,800 square miles on the northwest side of the San Joaquin Valley. The Tulare Formation of Pliocene and Pleistocene age, terrace deposits of Pleistocene age, and alluvium and flood-basin deposits of Pleistocene and Holocene age constitute the fresh ground-water reservoir Pre-Tertiary and Tertiary sedimentary and crystalline rocks, undifferentiated, underlie the valley and yield saline water. Hydrologically most important, the Tulare Formation is divided into a lower water-bearing zone confined by the Corcoran Clay Member and an upper zone that is confined, semiconfined, and unconfined in different parts of the area. Alluvium and flood-basin deposits are included in the upper zone. Surficial alluvium and flood-basin deposits contain a shallow water-bearing zone. Lower zone wells were flowing in 1908, but subsequent irrigation development caused head declines and land subsidence. Overdraft in both zones ended in 1951 with import of surface water. Bicarbonate water flows into the area from the Sierra Nevada and Diablo Range. Diablo Range water is higher in sulfate, chloride, and dissolved solids. Upper zone water averages between 400 and 1,200 mg/l (milligrams per liter) dissolved solids and water hardness generally exceeds 180 mg/l as calcium carbonate. Nitrate, fluoride, iron, and boron occur in excessive concentrations in water from some wells. Dissolved constituents in lower zone water generally are sodium chloride and sodium sulfate with higher dissolved solids concentration than water from the upper zone. The foothills of the Diablo Range provide favorable conditions for artificial recharge, but shallow water problems plague about 50 percent of the area and artificial recharge is undesirable at this time.

Hydrogeology of the surficial and intermediate aquifers of central Sarasota County, Florida

USGS Publications Warehouse

Duerr, A.D.; Wolansky, R.M.

1986-01-01

The geohydrologic units underlying a 300 sq mi area in central Sarasota County, Florida, consist of the surficial aquifer, intermediate aquifers (Tamiami-upper Hawthorn and lower Hawthorn-upper Tampa aquifers) and confining units, the Floridan aquifer system, and the sub-Floridan confining unit. The saturated thickness of the surficial aquifer ranges from about 40 to 75 ft and the water table is generally within 5 ft of land surface. The Tamiami-upper Hawthorn is the uppermost intermediate aquifer. The top of the aquifer ranges from about 50 ft to about 75 below sea level and has an average thickness of about 100 ft. The lower Hawthorne-upper Tampa aquifer is the lowermost intermediate aquifer. The top of the aquifer ranges from about 190 to about 220 ft below sea level and its thickness ranges from about 200 to 250 ft. The quality of water in the surficial and the two intermediate aquifers is acceptable for potable use except near the coast. Water from the Floridan aquifer system is used primarily for agricultural purposes because it is too mineralized for most other uses; therefore, the surficial and intermediate aquifers are developed for water supply. The artesian pressure of the various aquifers generally increases with depth. A more detailed geohydrologic description is presented for the Ringling-MacArthur Reserve, a 51 sq mi area in the central part of the county that may be used by Sarasota County as a future water supply. Average annual rainfall is 56 inches and evapotranspiration is about 42 in at the Reserve. The area has a high water table, many sloughs and swamps, and undeveloped land, making it an attractive site as a potential source of water. (Author 's abstract)

Concurrent Preoperative Presence of Hydronephrosis and Flank Pain Independently Predicts Worse Outcome of Upper Tract Urothelial Carcinoma

PubMed Central

Yeh, Hsin-Chih; Jan, Hau-Chern; Wu, Wen-Jeng; Li, Ching-Chia; Li, Wei-Ming; Ke, Hung-Lung; Huang, Shu-Pin; Liu, Chia-Chu; Lee, Yung-Chin; Yang, Sheau-Fang; Liang, Peir-In; Huang, Chun-Nung

2015-01-01

Objectives To investigate the impact of preoperative hydronephrosis and flank pain on prognosis of patients with upper tract urothelial carcinoma. Methods In total, 472 patients with upper tract urothelial carcinoma managed by radical nephroureterectomy were included from Kaohsiung Medical University Hospital Healthcare System. Clinicopathological data were collected retrospectively for analysis. The significance of hydronephrosis, especially when combined with flank pain, and other relevant factors on overall and cancer-specific survival were evaluated. Results Of the 472 patients, 292 (62%) had preoperative hydronephrosis and 121 (26%) presented with flank pain. Preoperative hydronephrosis was significantly associated with age, hematuria, flank pain, tumor location, and pathological tumor stage. Concurrent presence of hydronephrosis and flank pain was a significant predictor of non-organ-confined disease (multivariate-adjusted hazard ratio = 2.10, P = 0.025). Kaplan-Meier analysis showed significantly poorer overall and cancer-specific survival in patients with preoperative hydronephrosis (P = 0.005 and P = 0.026, respectively) and in patients with flank pain (P < 0.001 and P = 0.001, respectively) than those without. However, only simultaneous hydronephrosis and flank pain independently predicted adverse outcome (hazard ratio = 1.98, P = 0.016 for overall survival and hazard ratio = 1.87, P = 0.036 for and cancer-specific survival, respectively) in multivariate Cox proportional hazards models. In addition, concurrent presence of hydronephrosis and flank pain was also significantly predictive of worse survival in patient with high grade or muscle-invasive disease. Notably, there was no difference in survival between patients with hydronephrosis but devoid of flank pain and those without hydronephrosis. Conclusion Concurrent preoperative presence of hydronephrosis and flank pain predicted non-organ-confined status of upper tract urothelial carcinoma. When accompanied with flank pain, hydronephrosis represented an independent predictor for worse outcome in patients with upper tract urothelial carcinoma. PMID:26469704

Pleniglacial sedimentation process reconstruction on laminated lacustrine sediments from lava-dammed Paleolake Alf, West Eifel Volcanic Field (Germany)

NASA Astrophysics Data System (ADS)

Eichhorn, Luise; Pirrung, Michael; Zolitschka, Bernd; Büchel, Georg

2017-09-01

Differentiating between regularly seasonal, irregular and event-based clastic sedimentation is difficult if sedimentation structures resemble and dating methods are imprecise. In this study - clastic light and dark laminae from lava-dammed Paleolake Alf in the Late Pleistocene in the Quaternary West Eifel Volcanic Field are analyzed to clarify how they formed and if they are of annual origin and comparable to assumed periglacial varves from neighboring Lake Holzmaar. Therefore, a multiproxy approach is applied combining sediment thin section analysis which focuses on composition and structure with 14C dates. The results are compared to recently-formed annually-laminated clastic sediments of, e.g., the High Canadian Arctic. Observed sedimentation structures reveal sediment delivery by over- and interflows and deposition from suspension forming two characteristic microfacies: Type I graded laminae and Type II laminae with graded sublayers. Additionally, erosional bases and event deposits indicate episodic underflows. Thus, lamination is potentially seasonal but is significantly veiled by extreme runoff causing erosion and resuspension processes or a mixed water body preventing sediment delivery into the lake basin. However, sedimentation processes between watershed and lake could be reconstructed by comparing recent and paleosediment structures.

Jurassic-Cretaceous history of Cuba: implications for the evolution of the southern margin of the North American plate

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

Barros, J.A.; Rosencrantz, E.

The oldest Cuban sedimentary rocks, clastics of the Bajocian San Cayetano Fm. provide the earliest record of North American-Gondwana rifting as seen in Cuba. A similar clastic sequence is seen below the carbonates of the Bahamas platform. In the Pinar del Rio area, the San Cayetano is succeeded by Oxfordian limestones, the shallow water Jagua Fm. to the south and deeper water Francisco Fm. to the north. Both contain basaltic pillow lavas, related either to rifting or to leaky transform motion parallel to the margin. The Oxfordian units are overlain by Kimmeridgian to Tithonian pelagic limestones, the Guasasa and Artemisamore » Fms. The later interfingers with northerly derived calci-turbidites. North of the Escambray, silici-clastic fragments in late Jurassic pelagic limestones suggests that a basement high existed south of the platform until the Berriasian. The carbonate platform continues to shed debris along its southern edge throughout the Cretaceous. To the south an Aptian-Albian episode of turbidite deposition suggests that South America-Africa rifting caused tectonic disturbances in the Caribbean. Southerly derived volcanoclastics deposited during the Maastrichtian marks the start of the Cuban orogeny.« less

Detrital zircon evidence for the ternary sources of the Chinese Loess Plateau

NASA Astrophysics Data System (ADS)

Sun, Jimin; Ding, Zhongli; Xia, Xiaoping; Sun, Min; Windley, Brian F.

2018-04-01

The provenance of Chinese loess is fundamental for understanding its origin, transportation and climatic significance. In this paper, eight samples were collected for detrital zircon age analysis, five from different deserts, and three from the Jingbian Section in the northern Chinese Loess Plateau, covering an age range of 2.6-0.03 Ma. The new results, integrated with knowledge of relevant topography and wind patterns, demonstrate that the age spectra of the detrital zircons in the loess are different from those of the sands from the Tarim, Junggar and Qaidam basins, implying that these basins were not the sources of the silts of the Loess Plateau. Further analysis suggests that the three sources for the loess are: (1) clastic materials eroded from the mountains of the Central Asian Orogenic Belt (especially the Gobi Altai and Hangay), (2) clastic loess-sized materials generated by erosion of the Qilian Mountains in the NE Tibetan Plateau, and (3) minor clastic debris derived from the mountains of the North China Craton. Thus, silts of the Loess Plateau have a complex origin, although inland basins, long believed to be important sources, have only a minor role at most.

A ~20,000 year history of glacial variability in the tropical Andes recorded in lake sediments from the Cordillera Blanca, Peru

NASA Astrophysics Data System (ADS)

Stansell, N.; Rodbell, D. T.; Moy, C. M.

2010-12-01

Pro-glacial lake sediments from the Cordillera Blanca, Peru contain continuous records of climate variability spanning the Last Glacial Maximum to present day. Here we present results from two alpine lake basins in the Queshgue Valley (9.8°S, 77.3°W) that contain high-resolution records of clastic sediment deposition for the last ~20,000 years. Radiocarbon-dated sediment cores were scanned at 0.5 to 1.0 cm resolution using a profiling x-ray fluorescence scanner for major and minor element distributions. In addition, we measured down-core variations in magnetic susceptibility, organic carbon, biogenic silica and calcium carbonate. Samples of bedrock and sediments from glacial moraines in the Queshgue watershed were analyzed using an ICP-MS in order to fingerprint and trace the source of glacial sediments deposited in the lakes. The bedrock is dominated by a combination of granodiorite with high Sr concentrations and meta-sedimentary rocks with high Zr values. Because the glacial sediments proximal to the modern glacier terminus are composed mostly of the granodiorite end-member, we interpret changes in Sr and clastic sediment concentrations in the lake sediment profiles as proxies for past glacial variability. Preliminary results indicate that glaciers retreated soon after ~14,500 cal yr BP and remained less extensive during the remaining late Glacial Stage and early Holocene. Gradually increasing clastic sediments through the middle and late Holocene indicate that glaciers became progressively larger, or more erosive towards present day. However, this overall Holocene trend of increasing glacier extent was interrupted by multiple periods of centennial- to millennial-scale ice margin retreat. For example, relative peaks in clastic sediments occurred from ~14,500 to 6000, 5600 to 5000, 4600 to 4200, 3600 to 3200, 2800 to 2700, 2400 to 2200, 1750 to 1550, 1100 to 900 cal yr BP, and during the Little Ice Age (~700 to 50 cal yr BP), while periods of low clastic sedimentary influx took place from between ~6000 to 5600, 5000 to 4600, 4200 to 3600, 3200 to 2800, 2700 to 2400, and 2200 to 1750, 1550 to 1100, and 900 to 700 cal yr BP. Periods of ice advance in the Cordillera Blanca generally correspond to times of increased moisture-balance and lower temperatures that are recorded in other regional, terrestrial proxy records.

Improving age-depth models using sedimentary proxies for accumulation rates in fluvio-lacustrine deposits

NASA Astrophysics Data System (ADS)

Minderhoud, Philip S. J.; Cohen, Kim M.; Toonen, Willem. H. J.; Erkens, Gilles; Hoek, Wim Z.

2017-04-01

Lacustrine fills, including those of oxbow lakes in river floodplains, often hold valuable sedimentary and biological proxy records of palaeo-environmental change. Precise dating of accumulated sediments at levels throughout these records is crucial for interpretation and correlation of (proxy) data existing within the fills. Typically, dates are gathered from multiple sampled levels and their results are combined in age-depth models to estimate the ages of events identified between the datings. In this paper, a method of age-depth modelling is presented that varies the vertical accumulation rate of the lake fill based on continuous sedimentary data. In between Bayesian calibrated radiocarbon dates, this produces a modified non-linear age-depth relation based on sedimentology rather than linear or spline interpolation. The method is showcased on a core of an infilled palaeomeander at the floodplain edge of the river Rhine near Rheinberg (Germany). The sequence spans from 4.7 to 2.9 ka cal BP and consists of 5.5 meters of laminated lacustrine, organo-clastic mud, covered by 1 meter of peaty clay. Four radiocarbon dates provide direct dating control, mapping and dating in the wider surroundings provide additional control. The laminated, organo-clastic facies of the oxbow fill contains a record of nearby fluvial-geomorphological activity, including meander reconfiguration events and passage of rare large floods, recognized as fluctuations in coarseness and amount of allochthonous clastic sediment input. Continuous along-core sampling and measurement of loss-on-ignition (LOI) provided a fast way of expressing the variation in clastic sedimentation influx from the nearby river versus autochthonous organic deposition derived from biogenic production in the lake itself. This low-cost sedimentary proxy data feeds into the age-depth modelling. The sedimentology-modelled age-depth relation (re)produces the distinct lithological boundaries in the fill as marked changes in sedimentation rate. Especially the organo-clastic muddy facies subdivides in centennial intervals of relative faster and slower accumulation. For such intervals, sedimentation rates are produced that deviate 10 to 20% from that in simpler stepped linear age-models. For irregularly laminated muddy intervals of the oxbow fill - from which meaningful sampling for radiocarbon dating is more difficult than from peaty or slowly accumulating organic lake sediments - supplementing spotty radiocarbon sampling with continuous sedimentary proxy data creates more realistic age-depth modelling results.

Imaging the Crust in the Northern Sector of the 2009 L'Aquila Seismic Sequence through Oil Exploration Data Interpretation

NASA Astrophysics Data System (ADS)

Grazia Ciaccio, Maria; Improta, Luigi; Patacca, Etta; Scandone, Paolo; Villani, Fabio

2010-05-01

The 2009 L'Aquila seismic sequence activated a complex, about 40 km long, NW-trending and SW-dipping normal fault system, consisting of three main faults arranged in right-lateral en-echelon geometry. While the northern sector of the epicentral area was extensively investigated by oil companies, only a few scattered, poor-quality commercial seismic profiles are available in the central and southern sector. In this study we interpret subsurface commercial data from the northern sector, which is the area where is located the source of the strong Mw5.4 aftershock occurred on the 9th April 2009. Our primary goals are: (1) to define a reliable framework of the upper crust structure, (2) to investigate how the intense aftershock activity, the bulk of which is clustered in the 5-10 km depth range, relates to the Quaternary extensional faults present in the area. The investigated area lies between the western termination of the W-E trending Gran Sasso thrust system to the south, the SW-NE trending Mt. Sibillini thrust front (Ancona-Anzio Line Auctt.) to the north and west, and by the NNW-SSE trending, SW-dipping Mt. Gorzano normal fault to the east. In this area only middle-upper Miocene deposits are exposed (Laga Flysch and underlying Cerrogna Marl), but commercial wells have revealed the presence of a Triassic-Miocene sedimentary succession identical to the well known Umbria-Marche stratigraphic sequence. We have analyzed several confidential seismic reflection profiles, mostly provided by ENI oil company. Seismic lines are tied to two public wells, 5766 m and 2541 m deep. Quality of the reflection imaging is highly variable. A few good quality stack sections contain interpretable signal down to 4.5-5.5 s TWT, corresponding to depths exceeding 10-12 km and thus allowing crustal imaging at seismogenic depths. Key-reflectors for the interpretation correspond to: (1) the top of the Miocene Cerrogna marls, (2) the top of the Upper Albian-Oligocene Scaglia Group, (3) the Aptian-Albian Fucoid Marl horizon, (4) the top of the upper Jurassic "Calcari ad Aptici" Formation, (5) the top of the upper Triassic dolomites plus evaporites of the Burano Formation. Strong but discontinuous deep reflectors can be reasonably attributed to the Paleozoic-Trassic clastic sequence underlying the evaporites. Neogene compression is responsible for a system of NNW-SSE trending fault-propagation folds which have often grown on top of popup-like structures. Extensional features include shallow-seated low-angle faults, likely related to gravitational readjustments on top of compressional features, and younger NNW-SSE trending high-angle faults. The major high-angle fault in the investigated area is represented by the Mt. Gorzano Fault, a regional structure the surface trace of which is at least 20 km long. The Mt. Gorzano Fault is a listric fault that dips around 60° in the first 2 s TWT and flattens at greater depths until it becomes sub-horizontal at about 5 s TWT, i.e. at a depth averaging 12 kilometers. Depth converted sections, calibrated by well data, indicate that the bulk of the aftershock activity is confined between the Triassic dolomites plus evaporites and the underlying Paleozoic-Triassic terrigenous deposits, without affecting the overlying carbonates. Events alignment revealed by accurate Double-Difference relative locations suggests that the Mw5.4 aftershock activated a 12 km-long segment of the Mt. Gorzano Fault at depths ranging from 5 to 10-12 kilometers. Aftershocks cluster in the hanging-wall of the deep portion of the fault recognized in the stack sections, whose geometry is consistent with the fault plane highlighted by earthquakes alignment.

Aquifer test results, Green Swamp area, Florida

USGS Publications Warehouse

Tibbals, C.H.; Grubb, Hayes F.

1982-01-01

An aquifer test conducted in the Green Swamp area December 15-16 , 1975 was designed to stress the uppermost part of the Floridan aquifer so that the leakage characteristics of the overlying confining bed could be determined. A well tapping the upper part of the Floridan aquifer was pumped at a rate of about 1,040 gallons per minute for 35 hours; drawdown was measured in the Floridan aquifer and in two horizons in the confining bed. Analysis of the data indicates that the transmissivity of the uppper 160 feet of the Floridan is 13,000 square feet per day, the storage coefficient is about 0.0002.5, and the overlying confining bed leakance coefficient is about 0.02 to 0.025 per day. The vertical hydraulic diffusivity of the confining bed ranged from 610 square feet per day to 16,000 square feet per day. Results of the test indicate that, in the area of the test site, a Floridan aquifer well field would induce additional recharge to the Floridan. As a result of that increased recharge , water levels in the surficial aquifer would tend to stand lower, runoff from the area would tend to be less, and, perhaps, evapotranspiration would be less than normal.(USGS)

Hydrogeology of the surficial aquifer in the vicinity of a former landfill, Naval Submarine Base Kings Bay, Camden County, Georgia

USGS Publications Warehouse

Leeth, David C.

1999-01-01

Neogene and Quaternary sediments constitute the surficial aquifer beneath the study area; in descending order from youngest to oldest these include-the Quaternary undifferentiated surficial sand and Satilla Formation; the Pliocene(?) Cypresshead Formation; and the middle Miocene Coosawhatchie Formation. Beneath the surficial aquifer, the upper Brunswick aquifer consists of part of the lower Miocene Marks Head Formation. The surficial aquifer is divided into three water-bearing zones on the basis of lithologic and geophysical properties of sediments, hydraulic-head differences between zones, and differences in ground-water chemistry. The shallowest zone-the water-table zone-consists of medium to fine sand and clayey sand and is present from land surface to a depth of about 77 feet. Below the water-table zone, the confined upper water-bearing zone consists of medium to very coarse sand and is present from a depth of about 110 to 132 feet. Beneath the upper water-bearing zone, the confined lower water-bearing zone consists of coarse sand and very fine gravel and is present from a depth of about 195 to 237 feet. Hydraulic separation is suggested by differences in water chemistry between the water-table zone and upper water-bearing zone. The sodium chloride type water in the water-table zone differs from the calcium bicarbonate type water in the upper water-bearing zone. Hydraulic separation also is indicated by hydraulic head differences of more than 6.5 feet between the water-table zone and the upper water-bearing zone. Continuous and synoptic water-level measurements in the water-table zone, from October 1995 to April 1997, indicate the presence of a water-table high beneath and adjacent to the former landfill-the surface of which varies about 5 feet with time because of recharge and discharge. Water-level data from clustered wells also suggest that restriction of vertical ground-water flow begins to occur at an altitude of about 5 to 10 feet below sea level (35 to 40 feet below land surface) in the water-table zone because of the increasing clay content of the Cypresshead Formation.

Effect of the shell material and confinement type on the conversion efficiency of core/shell quantum dot nanocrystal solar cells

NASA Astrophysics Data System (ADS)

Sahin, Mehmet

2018-05-01

In this study, the effects of the shell material and confinement type on the conversion efficiency of core/shell quantum dot nanocrystal (QDNC) solar cells have been investigated in detail. For this purpose, the conventional, i.e. original, detailed balance model, developed by Shockley and Queisser to calculate an upper limit for the conversion efficiency of silicon p–n junction solar cells, is modified in a simple and effective way to calculate the conversion efficiency of core/shell QDNC solar cells. Since the existing model relies on the gap energy () of the solar cell, it does not make an estimation about the effect of QDNC materials on the efficiency of the solar cells, and gives the same efficiency values for several QDNC solar cells with the same . The proposed modification, however, estimates a conversion efficiency in relation to the material properties and also the confinement type of the QDNCs. The results of the modified model show that, in contrast to the original one, the conversion efficiencies of different QDNC solar cells, even if they have the same , become different depending upon the confinement type and shell material of the core/shell QDNCs, and this is crucial in the design and fabrication of the new generation solar cells to predict the confinement type and also appropriate QDNC materials for better efficiency.

Human enteric viruses in groundwater from a confined bedrock aquifer

USGS Publications Warehouse

Borchardt, M. A.; Bradbury, K.R.; Gotkowitz, M.B.; Cherry, J.A.; Parker, B.L.

2007-01-01

Confined aquifers are overlain by low-permeability aquitards that are commonly assumed to protect underlying aquifers from microbial contaminants. However, empirical data on microbial contamination beneath aquitards is limited. This study determined the occurrence of human pathogenic viruses in well water from a deep sandstone aquifer confined by a regionally extensive shale aquitard. Three public water-supply wells were each sampled 10 times over 15 months. Samples were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) for several virus groups and by cell culture for infectious enteroviruses. Seven of 30 samples were positive by RT-PCR for enteroviruses; one of these was positive for infectious echovirus 18. The virus-positive samples were collected from two wells cased through the aquitard, indicating the viruses were present in the confined aquifer. Samples from the same wells showed atmospheric tritium, indicating water recharged within the past few decades. Hydrogeologic conditions support rapid porous media transport of viruses through the upper sandstone aquifer to the top of the aquitard 61 m below ground surface. Natural fractures in the shale aquitard are one possible virus transport pathway through the aquitard; however, windows, cross-connecting well bores, or imperfect grout seals along well casings also may be involved. Deep confined aquifers can be more vulnerable to contamination by human viruses than commonly believed. ?? 2007 American Chemical Society.

Direct Evidence for Solid-like Hydrogen in a Nanoporous Carbon Hydrogen Storage Material at Supercritical Temperatures

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

Ting, Valeska P.; Ramirez-Cuesta, Anibal J.; Bimbo, Nuno

Here in this paper we report direct physical evidence that confinement of molecular hydrogen (H 2) in an optimized nanoporous carbon results in accumulation of hydrogen with characteristics commensurate with solid H 2 at temperatures up to 67 K above the liquid vapor critical temperature of bulk H 2. This extreme densification is attributed to confinement of 112 molecules in the optimally sized micropores, and occurs at pressures as low as 0.02 MPa. The quantities of contained, solid-like H 2 increased with pressure and were directly evaluated using in situ inelastic neutron scattering and confirmed by analysis of gas sorptionmore » isotherms. The demonstration of the existence of solid-like H 2 challenges the existing assumption that supercritical hydrogen confined in nanopores has an upper limit of liquid H 2 density. Thus, this insight offers opportunities for the development of more accurate models for the evaluation and design of nanoporous materials for high capacity adsorptive hydrogen storage.« less

Direct Evidence for Solid-like Hydrogen in a Nanoporous Carbon Hydrogen Storage Material at Supercritical Temperatures

DOE PAGES

Ting, Valeska P.; Ramirez-Cuesta, Anibal J.; Bimbo, Nuno; ...

2015-07-14

Here in this paper we report direct physical evidence that confinement of molecular hydrogen (H 2) in an optimized nanoporous carbon results in accumulation of hydrogen with characteristics commensurate with solid H 2 at temperatures up to 67 K above the liquid vapor critical temperature of bulk H 2. This extreme densification is attributed to confinement of 112 molecules in the optimally sized micropores, and occurs at pressures as low as 0.02 MPa. The quantities of contained, solid-like H 2 increased with pressure and were directly evaluated using in situ inelastic neutron scattering and confirmed by analysis of gas sorptionmore » isotherms. The demonstration of the existence of solid-like H 2 challenges the existing assumption that supercritical hydrogen confined in nanopores has an upper limit of liquid H 2 density. Thus, this insight offers opportunities for the development of more accurate models for the evaluation and design of nanoporous materials for high capacity adsorptive hydrogen storage.« less

Barometric response functions from borehole water level records and quantification of aquifer vulnerability

NASA Astrophysics Data System (ADS)

Odling, N. E.; Serrano, R. P.; Hussein, M.; Guadagnini, A.; Riva, M.

2013-12-01

In confined and semi-confined aquifers, borehole water levels respond to fluctuations in barometric pressure and this response can be used to estimate the properties of aquifer confining layers. We use this response as indicator of groundwater vulnerability for the semi-confined Chalk aquifer in East Yorkshire, UK. Time series data of borehole water levels are corrected for Earth tides and recharge, and barometric response functions (BRFs) estimated using cross-spectral deconvolution-averaging techniques. The resulting BRFs are fitted using a theoretical model of the BRF gain and phase for a semi-confined aquifer (Rojstaczer, 1988) to obtain confining layer properties. For all of the boreholes, non-zero hydraulic diffusivities for the confining layer were found indicating that the aquifer is semi-confined. A ';characteristic time scale' based on the hydraulic and pneumatic diffusivities of the confining layer is introduced as a measure of the degree of aquifer confinement and therefore groundwater vulnerability. The analytical model assumes that the confining layer and aquifer are homogeneous. However, in nature, confining layers are heterogeneous and groundwater vulnerability dominated by the presence of high diffusivity, high flow pathways through the confining layer to the aquifer. A transient numerical model (MODFLOW) was constructed to test the impact of such heterogeneities on the BRF. In the model, an observed barometric pressure time series is used as a boundary condition applied to the upper surface of the top unit of the model (representing the confining layer) and BRFs determined from the time series of model heads in the bottom unit (representing the aquifer). The results from a numerical model with a homogeneous confining layer were found to accurately reproduce the BRFs from a modified version of the analytical model. The introduction of a localized, high diffusive block in the confining layer was found to modify the BRF, reducing the gain amplitude while having limited impact on the phase. It was found that the BRF reflects the presence of a fully penetrating, high diffusivity heterogeneity up to several hundred meters distant from the observation borehole, and shows little sensitivity to the heterogeneity's horizontal dimension. Heterogeneities that are 50% partially penetrating do not significantly impact on the BRF and 90% penetrating heterogeneities can only be detected when large and close to the observation borehole. These results show that BRF gain may be particularly useful in detecting the presence of fully penetrating heterogeneities of high diffusivity within confining layers that potentially enhance groundwater vulnerability. This research has been funded in part through the EU ITN ';IMVUL' (PITN-GA-2008-212298). Reference: Rojstaczer, S. (1988) Determination of fluid-flow properties from the response of water levels in wells to atmospheric loading, Water Resources Research, 24(11), 1927-1938.

Respiratory Health Effects of Large Animal Farming Environments

PubMed Central

May, Sara; Romberger, Debra J.; Poole, Jill A.

2014-01-01

With increases in large animal-feeding operations to meet consumer demand, adverse upper and lower respiratory health effects in exposed agriculture workers is a concern. The aim of this study was to review large animal confinement feeding operational exposures associated with respiratory disease with focus on recent advances in the knowledge of causative factors and cellular and immunological mechanisms. A PubMed search was conducted with the following keywords: airway, farm, swine, dairy, horse, cattle inflammation, organic dust, endotoxin, and peptidoglycan that were published between 1980 and current. Articles were selected based on their relevance to environmental exposure and reference to airway diseases. Airway diseases included rhinitis, sinusitis, mucus membrane inflammation syndrome, asthma, chronic bronchitis, chronic obstructive pulmonary disease, hypersensitivity pneumonitis, and organic dust toxic syndrome. There is lower prevalence of IgE-mediated asthma and atopy in farmers and their children, but organic dust worsens existing asthma. Multiple etiologic factors are linked to disease including allergens, organic dusts, endotoxins, peptidoglycans and gases. Large animal confinement feeding operations contain a wide-diversity of microbes with increasing focus on Gram-positive bacteria and archeabacteria as opposed to Gram-negative bacteria in mediating disease. Toll-like receptors (TLR) and nucleotide oligomerization domain (NOD)-like innate immune pathways respond to these exposures. Finally, a chronic inflammatory adaptation, tolerance-like response in chronically exposed workers occurs. Large animal confinement farming exposures produces a wide spectrum of upper and lower respiratory tract diseases due to the complex diversity of organic dust, particulates, microbial cell wall components and gases and resultant activation of various innate immune receptor signaling pathways. PMID:23199220

Hydrogeology of the Croton-Ossining area, Westchester County, New York

USGS Publications Warehouse

Reynolds, Richard J.

1988-01-01

The hydrogeology of a 29-sq-mi area surrounding the village of Croton-on-Hudson, New York, is summarized on 6 sheets at 1:12 ,000 scale that show locations of wells and test holes, surficial geology, geologic sections, bedrock geology, land use, and soil permeability. The primary stratified-drift aquifer in this area is the Croton River aquifer, which consists of outwash sand and gravel that partly fills the Croton River valley from the New Croton Dam to the Hudson River--a distance of approximately 3 miles. The valley is narrow and ranges in width from 100 to 1,900 ft, and its v-notch bedrock floor ranges from 30 to 50 ft below sea level. Detailed hydrogeologic studies during 1936-38 showed the stratigraphy to consist of an upper water-table aquifer with a saturated thickness of about 35 ft, underlain by a silt and clay confining unit 8 to o0 ft in thickness that in turn is underlain by a lower confined outwash aquifer up to 40 ft thick. Aquifer-test data and laboratory permeability tests show that the average hydraulic conductivity of the upper outwash aquifer is 475 ft/d, and that of the lower confined aquifer is about 300 ft/d. The aquifer is recharged through direct precipitation, runoff from adjacent hillsides, and leakage under the new Croton Dam. Previous studies estimate the average leakage under the dam to be 0.65 Mgal/d and the total average daily recharge to the aquifer between New Croton Dam and Quaker Bridge to be 1.73 Mgal/d. (USGS)

Nicholas Thornburg | NREL

Science.gov Websites

;Consequences of Confinement for Alkene Epoxidation with Hydrogen Peroxide on Highly Dispersed Group 4 and 5 Size in the center and has one clockwise arc arrow moving from left to right connecting 5.4 nm M-SiO2 oxide and cyclohexane diol (using one H2O2 molecule), which is shown in the upper right and labeled

Seismic properties of Leg 195 serpentinites and their geophysical implications

USGS Publications Warehouse

Courtier, Anna M.; Hart, David J.; Christensen, Nikolas I.; Shinohara, Masanao; Salisbury, Matthew H.; Richter, Carl

2006-01-01

Knowledge of seismic velocities is necessary to constrain the lithologies encountered in seismic studies. We measured the seismic velocities, both compressional and shear wave, of clasts recovered during Ocean Drilling Program Leg 195 from a serpentine mud volcano, the South Chamorro Seamount. The compressional wave velocities of these clasts vary from a lower value of 5.5 km/s to an upper value of 6.1 km/s at a confining stress of 200 MPa. The shear wave velocities vary from a lower value of 2.8 km/s to an upper value of 3.3 km/s at a confining stress of 200 MPa. The densities of the samples vary from 2548 to 2701 kg/m3. These velocities and densities are representative of the highly serpentinized harzburgite and dunite mineralogy of the clasts. Velocities from a seismic study of the Izu-Bonin forearc wedge were used to calculate the degree of serpentinization in the forearc wedge. The seismic velocities of the forearc wedge are higher than the velocities of the clasts recovered from the South Chamorro Seamount, suggesting that the clasts are more serpentinized than the forearc wedge.

Steady-State Groundwater Flow Model for Great Neck, Long Island, New York

NASA Astrophysics Data System (ADS)

Chowdhury, S. H.; Klinger, D.; Sallemi, B. M.

2001-12-01

This paper describes a comprehensive groundwater flow model for the Great Neck section of Long Island, New York. The hydrogeology of this section of Long Island is dominated by a buried erosional valley consisting of sediments comparable to the North Shore Confining Unit. This formation cross-cuts, thus is in direct hydraulic connection with the Upper Glacial, North Shore Confining Unit, Raritan Clay, and Lloyd aquifers. The Magothy aquifer is present only in remote southern sections of the model area. In addition, various lenses of coarser material from the overlying Upper Glacial aquifer are dispersed throughout the area. Data collection consisted of gathering various parameter values from existing USGS reports. Hydraulic conductivity, porosity, estimated recharge values, evapotranspiration, well locations, and water level data have all been gathered from the USGS Office located in Coram, New York. Appropriate modeling protocol was followed throughout the modeling process. The computer code utilized for solving this numerical model is Visual MODFLOW as manufactured by Waterloo Hydrogeologic. Calibration and a complete sensitivity analysis were conducted. Modeled results indicate that the groundwater flow direction is consistent with what is viewed onsite. In addition, the model is consistent in returning favorable parameter results to historical data.

The integrated impacts of natural processes and human activities on groundwater salinization in the coastal aquifers of Beihai, southern China

NASA Astrophysics Data System (ADS)

Li, Qinghua; Zhang, Yanpeng; Chen, Wen; Yu, Shaowen

2018-03-01

Salinization in coastal aquifers is usually related to both seawater intrusion and water-rock interaction. The results of chemical and isotopic methods were combined to identify the origin and processes of groundwater salinization in Daguansha area of Beihai, southern China. The concentrations of the major ions that dominate in seawater (Cl-, Na+, Ca2+, Mg2+ and SO4 2- ), as well as the isotopic content and ratios (2H, 18O, 87Sr/86Sr and 13C), suggest that the salinization occurring in the aquifer of the coastal plain is related to seawater and that the prevailing hydrochemical processes are evaporation, mixing, dissolution and ion exchange. For the unconfined aquifer, groundwater salinization has occurred in an area that is significantly influenced by land-based sea farming. The integrated impacts of seawater intrusion from the Beibuwan Gulf and infiltration of seawater from the culture ponds are identified in the shallowest confined aquifer (I) in the middle of the area (site BBW2). Leakage from this polluted confined aquifer causes the salinization of groundwater in the underlying confined aquifer (II). At the coastal monitoring site (BBW3), confined aquifer I and lower confined aquifer II are heavily contaminated by seawater intrusion. The weak connectivity between the upper aquifers, and the seaward movement of freshwater, prevents saltwater from encroaching the deepest confined aquifer (III). A conceptual model is presented. Above all, understanding of the origin and processes of groundwater salinization will provide essential information for the planning and sustainable management of groundwater resources in this region.

Tailoring graphene layer-to-layer growth

NASA Astrophysics Data System (ADS)

Li, Yongtao; Wu, Bin; Guo, Wei; Wang, Lifeng; Li, Jingbo; Liu, Yunqi

2017-06-01

A layered material grown between a substrate and the upper layer involves complex interactions and a confined reaction space, representing an unusual growth mode. Here, we show multi-layer graphene domains grown on liquid or solid Cu by the chemical vapor deposition method via this ‘double-substrate’ mode. We demonstrate the interlayer-induced coupling effect on the twist angle in bi- and multi-layer graphene. We discover dramatic growth disunity for different graphene layers, which is explained by the ideas of a chemical ‘gate’ and a material transport process within a confined space. These key results lead to a consistent framework for understanding the dynamic evolution of multi-layered graphene flakes and tailoring the layer-to-layer growth for practical applications.

Nonvolatile semiconductor memory having three dimension charge confinement

DOEpatents

Dawson, L. Ralph; Osbourn, Gordon C.; Peercy, Paul S.; Weaver, Harry T.; Zipperian, Thomas E.

1991-01-01

A layered semiconductor device with a nonvolatile three dimensional memory comprises a storage channel which stores charge carriers. Charge carriers flow laterally through the storage channel from a source to a drain. Isolation material, either a Schottky barrier or a heterojunction, located in a trench of an upper layer controllably retains the charge within the a storage portion determined by the confining means. The charge is retained for a time determined by the isolation materials' nonvolatile characteristics or until a change of voltage on the isolation material and the source and drain permit a read operation. Flow of charge through an underlying sense channel is affected by the presence of charge within the storage channel, thus the presences of charge in the memory can be easily detected.

Clastic sedimentary rocks of the Michipicoten Volcanic-sedimentary belt, Wawa, Ontario

NASA Technical Reports Server (NTRS)

Ojakangas, R. W.

1983-01-01

The Wawa area, part of the Michipicoten greenstone belt, contains rock assemblages representative of volcanic sedimentary accumulations elsewhere on the shield. Three mafic to felsic metavolcanic sequences and cogenetic granitic rocks range in age from 2749 + or - 2Ma to 2696 + or - 2Ma. Metasedimentary rocks occur between the metavolcanic sequences. The total thickness of the supracrustal rocks may be 10,000 m. Most rocks have been metamorphosed under greenschist conditions. The belt has been studied earlier and is currently being remapped by Sage. The sedimentrologic work has been briefly summarized; two mainfacies associations of clastic sedimentary rocks are present - a Resedimented (Turbidite) Facies Association and a Nonmarine (Alluvial Fan Fluvial) Facies Association.

Play-level distributions of estimates of recovery factors for a miscible carbon dioxide enhanced oil recovery method used in oil reservoirs in the conterminous United States

USGS Publications Warehouse

Attanasi, E.D.; Freeman, P.A.

2016-03-02

The retention factor is the percentage of injected CO2 that is naturally retained in the reservoir. Retention factors were also estimated in this study. For clastic reservoirs, 90 percent of the estimated retention factors were between 21.7 and 32.1 percent, and for carbonate reservoirs, 90 percent were between 23.7 and 38.2 percent. The respective median values were 22.9 for clastic reservoirs and 26.1 for carbonate reservoirs. Both distributions were right skewed. The recovery and retention factors that were calculated are consistent with the corresponding factors reported in the literature.

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, May 2009

USGS Publications Warehouse

Ortiz, Anita G.

2009-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2009. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 48.53 inches for west-central Florida (from June 2008 through May 2009) was 4.12 inches below the historical cumulative average of 52.65 inches (Southwest Florida Water Management District, 2009). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 18-22, 2009. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman and Dixon, 2009). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition. The potentiometric contours are generalized to synoptically portray the head in a dynamic hydrologic system, taking due account of the variations in hydrogeologic conditions, such as differing depths of wells, nonsimultaneous measurements of water levels, variable effects of pumping, and changing climatic influence. The potentiometric contours may not conform exactly with the individual measurements of water levels.

Hydrogeology of the gray limestone aquifer in southern Florida

USGS Publications Warehouse

Reese, Ronald S.; Cunningham, Kevin J.

2000-01-01

Results from 35 new test coreholes and aquifer-test, water-level, and water-quality data were combined with existing hydrogeologic data to define the extent, thickness, hydraulic properties, and degree of confinement of the gray limestone aquifer in southern Florida. This aquifer, previously known to be present only in southeastern Florida (Miami-Dade, Broward, and Palm Beach Counties) below, and to the west of, the Biscayne aquifer, extends over most of central-south Florida, including eastern and central Collier County and southern Hendry County; it is the same as the lower Tamiami aquifer to the north, and it becomes the water-table aquifer and the upper limestone part of the lower Tamiami aquifer to the west. The aquifer generally is composed of gray, shelly, lightly to moderately cemented limestone with abundant shell fragments or carbonate sand, abundant skeletal moldic porosity, and minor quartz sand. The gray limestone aquifer comprises the Ochopee Limestone of the Tamiami Formation, and, in some areas, the uppermost permeable part of an unnamed formation principally composed of quartz sand. Underlying the unnamed formation is the Peace River Formation of the upper Hawthorn Group, the top of which is the base of the surficial aquifer system. Overlying the aquifer and providing confinement in much of the area is the Pinecrest Sand Member of the Tamiami Formation. The thickness of the aquifer is comparatively uniform, generally ranging from 30 to 100 feet. The unnamed formation part of the aquifer is up to 20 feet thick. The Ochopee Limestone accumulated in a carbonate ramp depositional system and contains a heterozoan carbonate-particle association. The principal rock types of the aquifer are pelecypod lime rudstones and floatstones and permeable quartz sands and sandstones. The pore types are mainly intergrain and separate vug (skeletal-moldic) pore spaces. The rock fabric and associated primary and secondary pore spaces combine to form a dual diffuse-carbonate and conduit flow system capable of producing high values of hydraulic conductivity. Transmissivity values of the aquifer are commonly greater than 50,000 feet squared per day to the west of Miami-Dade and Broward Counties. Hydraulic conductivity ranges from about 200 to 12,000 feet per day and generally increases from east to west; an east-to-west shallowing of the depositional profile of the Ochopee Limestone carbonate ramp contributes to this spatial trend. The aquifer contains two areas of high transmissivity, both of which trend northwest-southeast. One area extends through southern Hendry County. The other area extends through eastern Collier County, with a transmissivity as high as 300,000 feet squared per day; in this area, the aquifer is structurally high, the top of the aquifer is close to land surface, and it is unconfined to semiconfined. The confinement of the aquifer is good to the north and east in parts of southern Hendry, Palm Beach, Collier, Broward, and Miami-Dade Counties. In these areas, the upper confining unit approaches or is greater than 50 feet thick, and vertical leakance is less than 1.0 x 10-3 l/day. In most of the study area, the specific conductance in water from the gray limestone aquifer is 1,500 microsiemens per centimeter or less (chloride concentration of about 250 milligrams per liter or less). Areas where specific conductance is greater than 3,000 microsiemens per centimeter are found where there is a low horizontal-head gradient and the upper confining unit is greater than 50 feet thick. An area with specific conductance less than 1,500 microsiemens per centimeter extends from southern Hendry County to the southeast into western Broward County and coincides with an area of high transmissivity. However, much of this area has good confinement. The potentiometric gradient also is to the southeast in much of the area, and this area of low specific conductance is probably caused by a relatively rapid downgradient movement of fres

Hydrogeology and simulation of flow between the alluvial and bedrock aquifers in the upper Black Squirrel Creek basin, El Paso County, Colorado

USGS Publications Warehouse

Watts, K.R.

1995-01-01

Anticipated increases in pumping from the bedrock aquifers in El Paso County potentially could affect the direction and rate of flow between the alluvial and bedrock aquifers and lower water levels in the overlying alluvial aquifer. The alluvial aquifer underlies about 90 square miles in the upper Black Squirrel Creek Basin of eastern El Paso County. The alluvial aquifer consists of unconsolidated alluvial deposits that unconformably overlie siltstones, sandstones, and conglomerate (bedrock aquifers) and claystone, shale, and coal (bedrock confining units) of the Denver Basin. The bedrock aquifers (Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers) are separated by confining units (upper and lower Denver and the Laramie confining units) and overlie a relatively thick and impermeable Pierre confining unit. The Pierre confining unit is assumed to be a no-flow boundary at the base of the alluvial/ bedrock aquifer system. During 1949-90, substantial water-level declines, as large as 50 feet, in the alluvial aquifer resulted from withdrawals from the alluvial aquifer for irrigation and municipal supplies. Average recharge to the alluvial aquifer from infiltration of precipitation and surface water was an estimated 11.97 cubic feet per second and from the underlying bedrock aquifers was an estimated 0.87 cubic foot per second. Water-level data from eight bedrock observation wells and eight nearby alluvial wells indicate that, locally, the alluvial and bedrock aquifers probably are hydraulically connected and that the alluvial aquifer in the upper Black Squirrel Creek Basin receives recharge from the Denver and Arapahoe aquifers but-locally recharges the Laramie-Fox Hills aquifer. Subsurface-temperature profiles were evaluated as a means of estimating specific discharge across the bedrock surface (the base of the alluvial aquifer). However, assumptions of the analytical method were not met by field conditions and, thus, analyses of subsurface-temperature profiles did not reliably estimate specific discharge across the bedrock surface. The vertical hydraulic diffusivity of a siltstone and sandstone in the lower Denver confining unit was estimated, by an aquifer test, to be about 8 x 10'4 square foot per day. Physical and chemical characteristics of water from the bedrock aquifers in the study area generally differ from the physical and chemical characteristics of water from the alluvial aquifer, except for the physical and chemical characteristics of water from one bedrock well, which is completed in the Laramie-Fox Hills aquifer. In the southern part of the study area, physical and chemical characteristics of ground water indicate downward flow of water from the alluvial aquifer to the Laramie-Fox Hills aquifer. A three-dimensional numerical model was used to evaluate flow of water between the alluvial aquifer and underlying bedrock. Simulation of steady-state conditions indicates that flow from the bedrock aquifers to the alluvial aquifer was about 7 percent of recharge to the alluvial aquifer, about 0.87 cubic foot per second. The potential effects of withdrawal from the alluvial and bedrock aquifers at estimated (October 1989 to September 1990) rates and from the bedrock aquifers at two larger hypothetical rates were simulated for a 50-year projection period. The model simulations indicate that water levels in the alluvial aquifer will decline an average of 8.6 feet after 50 years of pumping at estimated October 1989 to September 1990 rates. Increases in withdrawals from the bedrock aquifers in El Paso County were simulated to: (1) Capture flow that currently discharges from the bedrock aquifers to springs and streams in upland areas and to the alluvial aquifer, (2) induce flow downward from the alluvial aquifer, and (3) accelerate the rate of waterlevel decline in the alluvial aquifer.

Deposition and deformation of fluvial-lacustrine sediments of the Upper Triassic-Lower Jurassic Whitmore Point Member, Moenave Formation, northern Arizona

NASA Astrophysics Data System (ADS)

Tanner, Lawrence H.; Lucas, Spencer G.

2010-01-01

The stratigraphic section of the Upper Triassic-Lower Jurassic Whitmore Point Member of the Moenave Formation at Potter Canyon, Arizona, comprises c. 26 m of gray to black shales and red mudstones interbedded with mainly sheet-like siltstones and sandstones. These strata represent deposition from suspension and sheetflow processes in shallow, perennial meromictic to ephemeral lakes, and on dry mudflats of the terminal floodout of the northward-flowing Moenave stream system. The lakes were small, as indicated by the lack of shoreline features and limited evidence for deltas. Changes in base level, likely forced by climate change, drove the variations between mudflat and perennial lacustrine conditions. Lenticular sandstones that occur across the outcrop face in the same stratigraphic interval in the lower part of the sequence represent the bedload fill of channels incised into a coarsening-upward lacustrine sequence following a fall in base level. These sandstones are distinctive for the common presence of over-steepened bedding, dewatering structures, and less commonly, folding. Deformation of these sandstones is interpreted as aseismic due to the lack of features typically associated with seismicity, such as fault-graded bedding, diapirs, brecciated fabrics and clastic dikes. Rapid deposition of the sands on a fluid-rich substrate produced a reverse density gradient that destabilized, and potentially fluidized the underlying, finer-grained sediments. This destabilization allowed synsedimentary subsidence of most of the channel sands, accompanied by longitudinal rotation and/or ductile deformation of the sand bodies.

New findings in the Eocene stratigraphy of Siwa-El Qara stretch, north western desert, Egypt

NASA Astrophysics Data System (ADS)

Osman, R.; Orabi, H.

2017-10-01

The Upper Hamra Member of Said and Issawi (1964) is a clastic/carbonate succession at Qor El Hamra east of the Bahariya Oasis in the Western Desert, Egypt. Earlier, the authors changed this member into a new informal name, the Al Humaymat formation (Priabonian) at the Siwa Oasis, which consists generally of carbonate sediments and overlays the mushroom rock of the Mokattam Formation (Late Lutetian). The thickness of the Al Humaymat formation is about 22 m recorded at the El Qara section and at the El Arag section reaches 5 m, where the collected fauna from this formation is represented by larger foraminifera Nummulites fabianii retiatus, Gaziryina aff. pulchellus, Silvestriella tetraedra and Grzybowskia sp. are assigned to Late Eocene (Priabonian). The base of the Al Humaymat formation is composed of grey marl to varicolored small scale tabular cross-bedded limestone, which reflects sheet flood deposits with a great unconformity surface; the middle part is composed of reefal limestone and sandy limestone. The upper part of this formation is characterized by earthy white limestone, which is overlain by very hard brown ferruginous paleosol bands and pockets, which represent distal floodplain deposits. Here it is interesting to notice that the Early and Late Priabonian decrease in depth of the sea over the studied area seems to be a reflection of a global decrease in depth of the sea as suggested from eustatic curves published by Haq et al., l987.

Middle Triassic back-arc basalts from the blocks in the Mersin Mélange, southern Turkey: Implications for the geodynamic evolution of the Northern Neotethys

NASA Astrophysics Data System (ADS)

Sayit, Kaan; Bedi, Yavuz; Tekin, U. Kagan; Göncüoglu, M. Cemal; Okuyucu, Cengiz

2017-01-01

The Mersin Mélange is a tectonostratigraphic unit within the allochthonous Mersin Ophiolitic Complex in the Taurides, southern Turkey. This chaotic structure consists of blocks and tectonic slices of diverse origins and ages set in a clastic matrix of Upper Cretaceous age. In this study, we examine two blocks at two different sections characterized by basaltic lava flows alternating with radiolarian-bearing pelagic sediments. The radiolarian assemblage extracted from the mudstone-chert alternation overlying the lavas yields an upper Anisian age (Middle Triassic). The immobile element geochemistry suggests that the lava flows are predominantly characterized by sub-alkaline basalts. All lavas display pronounced negative Nb anomalies largely coupled with normal mid-ocean basalt (N-MORB)-like high field strength element (HFSE) patterns. On the basis of geochemical modelling, the basalts appear to have dominantly derived from spinel-peridotite and pre-depleted spinel-peridotite sources, while some enriched compositions can be explained by contribution of garnet-facies melts from enriched domains. The overall geochemical characteristics suggest generation of these Middle Triassic lavas at an intra-oceanic back-arc basin within the northern branch of Neotethys. This finding is of significant importance, since these rocks may represent the presence of the oldest subduction zone found thus far from the Neotethyan branches. This, in turn, suggests that the rupturing of the Gondwanan lithosphere responsible for the opening of the northern branch of Neotethys should have occurred during the Lower Triassic or earlier.

A pure dipole analysis of the Gondwana apparent polar wander path: Paleogeographic implications in the evolution of Pangea

NASA Astrophysics Data System (ADS)

Gallo, L. C.; Tomezzoli, R. N.; Cristallini, E. O.

2017-04-01

The paleogeography of prebreakup Pangea at the beginning of the Atlantic Spreading has been a subject of debate for the past 50 years. Reconciling this debate involves theoretical corrections that cast doubt on available data and paleomagnetism as an effective tool for performing paleoreconstructions. This 50 year old debate focuses specifically on magnetic remanence and its ability to correctly record the inclination of the paleomagnetic field. In this paper, a selection of paleopoles was made to find the great circles containing the paleomagnetic pole and the respective sampling site. The true dipole pole (TDP) was then calculated by intersecting these great circles, effectively avoiding nondipolar contributions and inclination shallowing, in an innovative method. The great circle distance between each of these TDPs and the paleomagnetic means show the accuracy of paleomagnetic determinations in the context of a dominantly geocentric, axial, and dipolar geomagnetic field. The TDPs calculated allowed a bootstrap analysis to be performed to further consider the flattening factor that should be applied to the sedimentary-derived paleopoles. It is argued that the application of a single theoretical correction factor for clastic sedimentary-derived records could lead to a bias in the paleolatitude calculation and therefore to incorrect paleogeographic reconstructions. The unbiased APWP makes it necessary to slide Laurentia to the west in relation to Gondwana in a B-type Pangea during the Upper Carboniferous, later evolving, during the Early Permian, to reach the final A-type Pangea configuration of the Upper Permian.

Recent Trends and Advances in Sedimentology.

ERIC Educational Resources Information Center

Suttner, Lee J.

1979-01-01

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

Massive sulfide metallogenesis at a late Mesozoic sediment-covered spreading axis: Evidence from the Franciscan complex and contemporary analogues

USGS Publications Warehouse

Koski, Randolph A.; Lamons, Roberta C.; Dumoulin, Julie A.; Bouse, Robin M.

1993-01-01

The Island Mountain deposit, an anomalous massive sulfide in the Central belt of the Franciscan subduction complex, northern California Coast Ranges, formed during hydrothermal activity in a sediment-dominated paleo-sea-floor environment. Although the base of the massive sulfide is juxtaposed against a 500-m-wide melange band, its gradational upper contact within a coherent sequence of sandstone, siltstone, and mudstone indicates that hydrothermal activity was concurrent with turbidite deposition. Accumulations of sulfide breccia and clastic sulfide were produced by mass wasting of the sulfide mound prior to burial by turbidites. The bulk composition of sulfide samples (pyrrhotite rich; high Cu, As, and Au contents; radiogenic Pb isotope ratios) is consistent with a hydrothermal system dominated by fluid-sediment interaction. On the basis of a comparison with possible contemporary tectonic analogues at the southern Gorda Ridge and the Chile margin triple junction, we propose that massive sulfide mineralization in the Central belt of the Franciscan complex resulted from hydrothermal activity at a late Mesozoic sediment-covered ridge axis prior to collision with the North American plate.

Interpretation of sedimentological processes of coarse-grained deposits applying a novel combined cluster and discriminant analysis

NASA Astrophysics Data System (ADS)

Farics, Éva; Farics, Dávid; Kovács, József; Haas, János

2017-10-01

The main aim of this paper is to determine the depositional environments of an Upper-Eocene coarse-grained clastic succession in the Buda Hills, Hungary. First of all, we measured some commonly used parameters of samples (size, amount, roundness and sphericity) in a much more objective overall and faster way than with traditional measurement approaches, using the newly developed Rock Analyst application. For the multivariate data obtained, we applied Combined Cluster and Discriminant Analysis (CCDA) in order to determine homogeneous groups of the sampling locations based on the quantitative composition of the conglomerate as well as the shape parameters (roundness and sphericity). The result is the spatial pattern of these groups, which assists with the interpretation of the depositional processes. According to our concept, those sampling sites which belong to the same homogeneous groups were likely formed under similar geological circumstances and by similar geological processes. In the Buda Hills, we were able to distinguish various sedimentological environments within the area based on the results: fan, intermittent stream or marine.

Does a strong pycnocline impact organic-matter preservation and accumulation in an anoxic setting? The case of the Orca Basin, Gulf of Mexico

NASA Astrophysics Data System (ADS)

Tribovillard, Nicolas; Bout-Roumazeilles, Viviane; Sionneau, Thomas; Serrano, Jean Carlos Montero; Riboulleau, Armelle; Baudin, François

2009-01-01

The Orca Basin (an intraslope depression located in the Gulf of Mexico) collects sedimentary particles of terrestrial origin (clastic and organic particles mainly supplied by the Mississippi River) and of marine origin (biogenic productivity). The basin is partly filled with dense brines leached from salt diapirs cropping out on the sea floor, and is permanently stratified. A strong pycnocline induces anoxic bottom conditions, expectedly favorable to organic matter (OM) preservation. Here, we report on OM in the upper 750 cm below sea floor of Core MD02-2552 (Holocene). The organic content is dominated by marine-derived amorphous OM. The organic assemblage is unexpectedly degraded to some extent, which may be accounted for by a relatively long residence time of organic particles at the halocline-pycnocline at ˜2240 m. Thus the organic particles are temporarily trapped and kept in contact with the dissolved oxygen-rich overlying water mass. Lastly, the land-derived organic fraction shows co-variations with the land-derived clay mineral supply.

Massive sulfide metallogenesis at a late Mesozoic sediment-covered spreading axis: Evidence from the Franciscan complex and contemporary analogues

NASA Astrophysics Data System (ADS)

Koski, Randolph A.; Lamons, Roberta C.; Dumoulin, Julie A.; Bouse, Robin M.

1993-02-01

The Island Mountain deposit, an anomalous massive sulfide in the Central belt of the Franciscan subduction complex, northern California Coast Ranges, formed during hydrothermal activity in a sediment-dominated paleo-sea-floor environment. Although the base of the massive sulfide is juxtaposed against a 500-m-wide melange band, its gradational upper contact within a coherent sequence of sandstone, siltstone, and mudstone indicates that hydrothermal activity was concurrent with turbidite deposition. Accumulations of sulfide breccia and clastic sulfide were produced by mass wasting of the sulfide mound prior to burial by turbidites. The bulk composition of sulfide samples (pyrrhotite rich; high Cu, As, and Au contents; radiogenic Pb isotope ratios) is consistent with a hydrothermal system dominated by fluid-sediment interaction. On the basis of a comparison with possible contemporary tectonic analogues at the southern Gorda Ridge and the Chile margin triple junction, we propose that massive sulfide mineralization in the Central belt of the Franciscan complex resulted from hydrothermal activity at a late Mesozoic sediment-covered ridge axis prior to collision with the North American plate.

South Sumatra Basin Province, Indonesia; the Lahat/Talang Akar-Cenozoic total petroleum system

USGS Publications Warehouse

Bishop, Michele G.

2000-01-01

Oil and gas are produced from the onshore South Sumatra Basin Province. The province consists of Tertiary half-graben basins infilled with carbonate and clastic sedimentary rocks unconformably overlying pre-Tertiary metamorphic and igneous rocks. Eocene through lower Oligocene lacustrine shales and Oligocene through lower Miocene lacustrine and deltaic coaly shales are the mature source rocks. Reserves of 4.3 billion barrels of oil equivalent have been discovered in reservoirs that range from pre-Tertiary basement through upper Miocene sandstones and carbonates deposited as synrift strata and as marine shoreline, deltaic-fluvial, and deep-water strata. Carbonate and sandstone reservoirs produce oil and gas primarily from anticlinal traps of Plio-Pleistocene age. Stratigraphic trapping and faulting are important locally. Production is compartmentalized due to numerous intraformational seals. The regional marine shale seal, deposited by a maximum sea level highstand in early middle Miocene time, was faulted during post-depositional folding allowing migration of hydrocarbons to reservoirs above the seal. The province contains the Lahat/Talang Akar-Cenozoic total petroleum system with one assessment unit, South Sumatra.

Clastic dikes of the Hatrurim basin (western flank of the Dead Sea) as natural analogues of alkaline concretes: Mineralogy, solution chemistry, and durability

NASA Astrophysics Data System (ADS)

Sokol, E. V.; Gaskova, O. L.; Kozmenko, O. A.; Kokh, S. N.; Vapnik, E. A.; Novikova, S. A.; Nigmatulina, E. N.

2014-11-01

This study shows that the mineral assemblages from clastic dikes in areas adjacent to the Dead Sea graben may be considered as natural analogues of alkaline concretes. The main infilling material of the clastic dikes is composed of well-sorted and well-rounded quartz sand. The cement of these hard rocks contains hydroxylapophyllite, tacharanite, calcium silicate hydrates, opal, calcite, and zeolite-like phases, which is indicative of a similarity of the natural cementation processes and industrial alkaline concrete production from quartz sands and industrial alkaline cements. The quartz grains exhibit a variety of reaction textures reflecting the interaction with alkaline solutions (opal and calcium hydrosilicate overgrowths; full replacement with apophyllite or thomsonite + apophyllite). The physicochemical analysis and reconstruction of the chemical composition of peralkaline Ca, Na, and K solutions that formed these assemblages reveal that the solutions evolved toward a more stable composition of zeolite-like phases, which are more resistant to long-term chemical weathering and atmospheric corrosion. The 40Ar/39Ar age of 6.2 ± 0.7 Ma obtained for apophyllite provides conclusive evidence for the high corrosion resistance of the assemblages consisting of apophyllite and zeolite-like phases.

3D modelling of mechanical peat properties in the Holocene coastal-deltaic sequence of the Netherlands

NASA Astrophysics Data System (ADS)

Koster, Kay; Stouthamer, Esther; Cohen, Kim; Stafleu, Jan; Busschers, Freek; Middelkoop, Hans

2016-04-01

Peat is abundantly present within the Holocene coastal-deltaic sequence of the Netherlands, where it is alternating with clastic fluvial, estuarine and lagoonal deposits. The areas that are rich in peat are vulnerable to land subsidence, resulting from consolidation and oxidation, due to loading by overlying deposits, infrastructure and buildings, as well as excessive artificial drainage. The physical properties of the peat are very heterogeneous, with variable clastic admixture up to 80% of its mass and rapid decrease in porosity with increasing effective stress. Mapping the spatial distribution of the peat properties is essential for identifying areas most susceptible to future land subsidence, as mineral content determines volume loss by oxidation, and porosity influences the rate of consolidation. Here we present the outline of a study focusing on mapping mechanical peat properties in relation to density and amount of admixed clastic constituents of Holocene peat layers (in 3D). In this study we use a staged approach: 1) Identifying soil mechanical properties in two large datasets that are managed by Utrecht University and the Geological Survey. 2) Determining relations between these properties and palaeogeographical development of the area by evaluating these properties against known geological concepts such as distance to clastic source (river, estuary etc.). 3) Implementing the obtained relations in GeoTOP, which is a 3D geological subsurface model of the Netherlands developed by the Geological Survey. The model will be used, among others, to assess the susceptibility of different areas to peat related land subsidence and load bearing capacity of the subsurface. So far, our analysis has focused stage 1, by establishing empirical relations between mechanical peat properties in ~70 paired (piezometer) cone penetration tests and continuously cored boreholes with LOI measurements. Results show strong correlations between net cone resistance (qn), excess pore water (u1-u0), and total vertical stress (σvo), suggesting that the overburden strongly controls the vertical differential susceptibility of peat layers to consolidation.

Monitoring the formation of clastic-biogenic varves to improve the quality of paleoclimate reconstructions

NASA Astrophysics Data System (ADS)

Ojala, A.; Kosonen, E.; Weckstrom, J.; Korkonen, S.

2013-12-01

Annually laminated (varved) sediments are excellent archives for studies of past climate and environmental changes, as they allow analysis of the undisturbed 'in-situ' sediment composition and structure with a seasonal-scale resolution. Among those, clastic-biogenic varved lake sediments have been found and investigated in Finland and Sweden during the last decades. An important prerequisite for applying varved sediments in palaeoenvironmental studies is understanding the mechanism of rhythmic sedimentation and the composition of different laminae representing annual sedimentation events. This knowledge is essential for verifying the annual nature of varves, for investigating the main factors controlling seasonal sedimentation, and for the interpretations of past environmental changes. Here, we report detailed information on the seasonal sedimentation of different varve components and palaeolimnological indicators (diatoms, chrysophycaean cysts) in Lake Nautajärvi, Finland, using near-bottom sediment trap monitoring. The monitoring results strongly support previous interpretations of the formation of clastic-biogenic varves in Fennoscandian lakes. The results also indicate that seasonal sediment fluxes correspond with regional climate and environmental changes. They clearly reveal differences in the amount of seasonal sediment flux between two climatologically and hydrologically different years. For example, higher snow storage in winter and the discharge intensity during the following spring snow melt clearly increases the suspended sediment load, transportation, and net accumulation of detrital mineral matter during spring and early summer. A prolonged autumn and subsequent freezing and thawing cycles in winter, conversely, results in an incremental but slow accumulation of assorted mineral matter and organic particles during winter, whereas the subsequent spring flooding and detrital sediment yield are diminished and thinner clastic laminae are formed. The accumulation rates of diatoms and chrysophyte cysts suggest these algal groups are more dependent on seasonal processes (e.g. spring and autumnal overturn) than on rapid, short-lived environmental episodes such as the spring discharge peak.

Geochemical and isotopic composition of ground water with emphasis on sources of sulfate in the upper Floridan Aquifer and intermediate aquifer system in southwest Florida

USGS Publications Warehouse

Sacks, Laura A.; Tihansky, Ann B.

1996-01-01

In southwest Florida, sulfate concentrations in water from the Upper Floridan aquifer and overlying intermediate aquifer system are commonly above 250 milligrams per liter (the drinking water standard), particularly in coastal areas. Possible sources of sulfate include dissolution of gypsum from the deeper part of the Upper Floridan aquifer or the middle confining unit, saltwater in the aquifer, and saline waters from the middle confining unit and Lower Floridan aquifer. The sources of sulfate and geochemical processes controlling ground-water composition were evaluated for the Peace and Myakka River Basins and adjacent coastal areas of southwest Florida. Samples were collected from 63 wells and a saline spring, including wells finished at different depth intervals of the Upper Floridan aquifer and intermediate aquifer system at about 25 locations. Sampling focused along three ground-water flow paths (selected based on a predevelopment potentiometric-surface map). Ground water was analyzed for major ions, selected trace constituents, dissolved organic carbon, and stable isotopes (delta deuterium, oxygen-18, carbon-13 of inorganic carbon, and sulfur-34 of sulfate and sulfide); the ratio of strontium-87 to strontium-86 was analyzed for waters along one of the flow paths. Chemical and isotopic data indicate that dedolomitization reactions (gypsum and dolomite dissolution and calcite precipitation) control the chemical composition of water in the Upper Floridan aquifer in inland areas. This is confirmed by mass-balance modeling between wells in the shallowest interval in the aquifer along the flow paths. However, gypsum occurs deeper in the aquifer than these wells. Upwelling of sulfate-rich water that previously dissolved gypsum in deeper parts of the aquifer is a more likely source of sulfate than gypsum dissolution in shallow parts of the aquifer. This deep ground water moves to shallower zones in the aquifer discharge area. Saltwater from the Upper Floridan aquifer has not dissolved significant amounts of gypsum compared to fresher water in the aquifer. This is consistent with a shallow seawater source for the saltwater, rather than a deeper source from the underlying middle confining unit or Lower Floridan aquifer, which would have elevated sulfate concentrations. Ion exchange and dolomitization may be important reactions for saltwater in the aquifer. According to geochemical modeling, the freshwater end member for water in the saltwater mixing zone in the southwestern part of the study area is not upgradient water from the Upper Floridan aquifer that dissolved gypsum. Instead, this water appears to be isolated from the regional freshwater flow system and may be part of a more localized flow system. The chemical and isotopic composition of water in the intermediate aquifer system is controlled by differences in extent of reactions with aquifer minerals, upward leakage from the Upper Floridan aquifer, and saltwater mixing. In inland areas, water generally is characterized by relatively low sulfate concentrations (less than 250 milligrams per liter) and differences in extent of carbonate mineral dissolution. Some inland waters have elevated chloride concentrations, which may be related to evaporation prior to recharge. In coastal Sarasota County and in isolated inland areas, water from the intermediate aquifer system has high sulfate concentrations characteristic of dedolomitization waters from the Upper Floridan aquifer. The chemical and isotopic composition of these waters is controlled by upward leakage from the Upper Floridan aquifer, which naturally occurs in the discharge area but may be locally enhanced by pumping or interconnection of wells open to both aquifer systems. In western Charlotte County, the waters are dominated by sodium and chloride, and their compositions are consistent with mixing between saltwater and inland intermediate aquifer system water that has not been influenced by discharge from the

Geohydrology and Water Quality of the Valley-Fill Aquifer System in the Upper Sixmile Creek and West Branch Owego Creek Valleys in the Town of Caroline, Tompkins County, New York

USGS Publications Warehouse

Miller, Todd S.

2009-01-01

In 2002, the U.S. Geological Survey, in cooperation with the Town of Caroline and Tompkins County Planning Department, began a study of the valley-fill aquifer system in upper Sixmile Creek and headwaters of West Branch Owego Creek valleys in the Town of Caroline, NY. The purpose of the study is to provide geohydrologic data to county and town planners as they develop a strategy to manage and protect their water resources. The first aquifer reach investigated in this series is in the Town of Caroline and includes the upper Sixmile Creek valley and part of West Branch Owego Creek valley. The portions of the valley-fill aquifer system that are comprised of saturated coarse-grained sediments including medium to coarse sand and sandy gravel form the major aquifers. Confined sand and gravel units form the major aquifers in the western and central portions of the upper Sixmile Creek valley, and an unconfined sand and gravel unit forms the major aquifer in the eastern portion of the upper Sixmile Creek valley and in the headwaters of the West Branch Owego Creek valley. The valley-fill deposits are thinnest near the edges of the valley where they pinch out along the till-mantled bedrock valley walls. The thickness of the valley fill in the deepest part of the valley, at the western end of the study area, is about 100 feet (ft); the thickness is greater than 165 ft on top of the Valley Heads Moraine in the central part of the valley. An estimated 750 people live over and rely on groundwater from the valley-fill aquifers in upper Sixmile Creek and West Branch Owego Creek valleys. Most groundwater withdrawn from the valley-fill aquifers is pumped from wells with open-ended 6-inch diameter casings; the remaining withdrawals are from shallow dug wells or cisterns that collect groundwater that discharges to springs (especially in the Brooktondale area). The valley-fill aquifers are the sources of water for about 200 households, several apartment complexes, two mobile home parks, a school, and several farms and small businesses. Most groundwater that is withdrawn from pumped wells is returned to the groundwater system via septic systems. Groundwater in the upper and basal confined aquifers in the upper Sixmile Creek valley is under artesian conditions everywhere except where the water discharges to springs along bluffs in the western end of the Sixmile Creek valley. Principal sources of recharge to the confined aquifers are (1) the sides of the valley where the confined aquifers may extend up along the flank of the bedrock valley wall and crop out at land surface or are overlain and in contact with surficial coarse-grained deltaic and fluvial sediments that provide a pathway through which direct precipitation and seepage losses from tributary streams can reach the buried aquifers, or (2) where the buried aquifers are isolated and receive recharge only from adjacent fine-grained sediment and bedrock. The base-flow and runoff components of total streamflow at two streamgages, Sixmile Creek at Brooktondale and Sixmile Creek at Bethel Grove, were calculated using hydrograph-separation techniques from 2003 to 2007 discharge records. Base flow constituted 64 and 56 percent of the total annual flow at the Brooktondale and Bethel Grove streamgages, respectively. Water-quality samples were collected from 2003 to 2005, with 10 surface-water samples collected seasonally during base-flow conditions at the Sixmile Creek at Brooktondale streamgage, and 12 samples were collected during base-flow conditions at several selected tributaries from 2004 to 2005. The predominant cation detected in the surface-water samples was calcium, but moderate amounts of magnesium, silica, and sodium were also detected; the major anions were bicarbonate, chloride, and sulfate. Sodium and chloride concentrations were relatively low in all samples but increased downstream from the Sixmile Creek sampling site at Six Hundred Road near Slaterville Springs, NY, to B

Development and Calibration of a Variable-Density Numerical Model of a Deep-well Injection Site near the Southeastern Florida Coast

NASA Astrophysics Data System (ADS)

Dausman, A.; Langevin, C.; Sukop, M.; Walsh, V.

2006-12-01

The South District Wastewater Treatment Plant (SDWWTP), located in southeastern Miami-Dade County about 1 mi west of the Biscayne Bay coastline, is the largest capacity deep-well injection plant in the United States. Currently, about 100 Mgal/d of partially treated, essentially fresh (less than 1000 mg/L total dissolved solids) effluent is injected through 17 wells (each approximately 2500 ft below land surface) into the highly transmissive, lower-temperature, saline Boulder Zone composed of highly fractured dolomite. A thin confining unit called the Delray Dolomite, which is 8-16 ft thick, overlies the intended injection zone at the site. Although the Delray Dolomite has a vertical hydraulic conductivity estimated between 0.001 and 0.00001 ft/d, well casings for 10 of the 17 wells do not extend beneath the unit. A 700-ft-thick middle confining unit, with estimated vertical hydraulic conductivities between 0.1 and 28 ft/d, overlies the Delray Dolomite and separates it from the Upper Floridan aquifer. Protected by the Safe Drinking Water Act (SDWA), the Upper Floridan aquifer contains water that is less than 10,000 mg/L total dissolved solids. In southern Florida, this aquifer is used for reverse osmosis, blending with other waters, and as a reservoir for aquifer storage and recovery. At the SDWWTP, ammonia concentrations that exceed background conditions have been observed in monitoring wells open in and above the middle confining unit, indicating upward vertical migration of effluent, possibly toward the Upper Floridan aquifer. The U.S. Geological Survey currently is developing a variable-density groundwater flow and solute transport model for the Floridan aquifer system in Miami-Dade County. This model includes the injection of treated wastewater at the SDWWTP. The developed numerical model uses SEAWAT, a code that calculates variable- density flow as a function of salinity, to capture the buoyancy effects at the site and along the coast. Simulation efforts have been designed to determine likely mechanisms for vertical fluid migration as well as predict future movement of the effluent. Two alternative mechanisms for upward fluid migration are being tested with the model: (1) site-wide, diffuse upward movement through the Delray Dolomite and middle confining unit with all 17 injection wells; and (2) localized upward movement from the shallow casing depths at 10 of the 17 wells. The parameter estimation program, PEST, has estimated two different hydraulic conductivity configurations for the Delray Dolomite, middle confining unit, and other layers under these two possible conditions. The different parameter sets have yielded two satisfactory model calibrations. Results of these calibrations indicate that vertical effluent migration potentially is occurring either from (1) the 10 wells open above the Delray Dolomite, with virtually no effluent migration through the Delray Dolomite; or (2) all 17 wells open above and below the Delray Dolomite, with effluent migration through the Delray Dolomite.

The Lusi mud eruption dynamics: constraints from field data.

NASA Astrophysics Data System (ADS)

Mazzini, Adriano; Sciarra, Alessandra; Lupi, Matteo; Mauri, Guillaume; Karyono, Karyono; Husein, Alwi; Aquino, Ida; Ricco, Ciro; Obermann, Anne; Hadi, Soffian

2017-04-01

The Indonesian Lusi eruption has been spewing boiling water, gas, and sediments since the 29th of May 2006. Initially, numerous aligned eruptions sites appeared along the Watukosek fault system that was reactivated after the Yogyakarta earthquake occurring the 27th of May in the Java Island. Since its birth Lusi erupted with a pulsating behavior showing intermittent periods of stronger activity resulting in higher fluids and solid emissions intervals. Since 2010 two active vents are constantly active. We conducted detailed monitoring of such clastic geysering activity and this allowed us to distinguish four distinct phases that follow each other and that reoccur every 30 minutes: (1) regular bubbling activity (constant emission of water, mud breccia, and gas); (2) clastic geysering phase with intense bubbling (consisting in reduced vapor emission and more powerful diffused mud bursting); (3) clastic geysering with mud bursts and intense vapour discharge (typically dense plume that propagates up to 100 m in height); (4) quiescent phase marking the end of the geysering activity (basically no gas emissions or bursts observed). In order to better understand this pulsating behavior and to constrain the mechanisms controlling its activity, we designed a multidisciplinary monitoring of the eruption site combining the deployment of numerous instruments around the crater site. Processing of the collected data reveals the dynamic activity of Lusi's craters. Satellite images show that the location of these vents migrated along a NE-SW direction. This is subparallel to the direction of the Watukosek fault system that is the zone of (left) lateral deformation upon which Lusi developed in 2006. Coupling HR camera images with broadband and short period seismic stations allowed us to describe the seismic signal generated by clastic geysering and to constrain the depth of the source generating the signal. We measure a delay between the seismic (harmonic) record and the associated clastic geyser explosion of approximately 3 s. This, in agreement with previous studies, corresponds to a source located some tens of meters depth inside the conduits. We ascribe the harmonic seismic signal to rise of batches of H2O-CO2-CH4 fluids inside the conduit. Once they approach the water-vapour region the sudden pressure drop triggers flashing and the exsolution of the dissolved CO2 and CH4. In the last part of our study we verified whether the powerful clastic geysering (emitting jets up to 20 m high) may induce local deformation of the mud edifice. During the stronger geysering events we measure an increase and drop of gravity overtime that are related to change of mud density within the feeder conduit. We process continuous camera recordings with a video magnifying tool capable of enhancing small variations in the recorded images. Results highlight that major eruptive events are preceded by a deformation of the mud edifice surrounding the vents. Ongoing studies aim to verify if these events are also captured by the tiltmeter measurements. This study represents a step forward to better understand the activity that characterizes Lusi. Further studies will help to better constrain the reactions and dynamics ongoing inside the conduit.

Agricultural lung diseases.

PubMed Central

Kirkhorn, S R; Garry, V F

2000-01-01

Agriculture is considered one of the most hazardous occupations. Organic dusts and toxic gases constitute some of the most common and potentially disabling occupational and environmental hazards. The changing patterns of agriculture have paradoxically contributed to both improved working conditions and increased exposure to respiratory hazards. Animal confinement operations with increasing animal density, particularly swine confinement, have contributed significantly to increased intensity and duration of exposure to indoor air toxins. Ongoing research has implicated bacterial endotoxins, fungal spores, and the inherent toxicity of grain dusts as causes of upper and lower airway inflammation and as immunologic agents in both grain and animal production. Animal confinement gases, particularly ammonia and hydrogen sulfide, have been implicated as additional sources of respiratory irritants. It has become evident that a significant percentage of agricultural workers have clinical symptoms associated with long-term exposure to organic dusts and animal confinement gases. Respiratory diseases and syndromes, including hypersensitivity pneumonitis, organic dust toxic syndrome, chronic bronchitis, mucous membrane inflammation syndrome, and asthmalike syndrome, result from ongoing acute and chronic exposures. In this review we focus upon the emerging respiratory health issues in a changing agricultural economic and technologic environment. Environmental and occupational hazards and exposures will be emphasized rather than clinical diagnosis and treatment. Methods of prevention, from both engineering controls and personal respiratory perspectives, are also addressed. PMID:10931789

Effect of the shell material and confinement type on the conversion efficiency of core/shell quantum dot nanocrystal solar cells.

PubMed

Sahin, Mehmet

2018-05-23

In this study, the effects of the shell material and confinement type on the conversion efficiency of core/shell quantum dot nanocrystal (QDNC) solar cells have been investigated in detail. For this purpose, the conventional, i.e. original, detailed balance model, developed by Shockley and Queisser to calculate an upper limit for the conversion efficiency of silicon p-n junction solar cells, is modified in a simple and effective way to calculate the conversion efficiency of core/shell QDNC solar cells. Since the existing model relies on the gap energy ([Formula: see text]) of the solar cell, it does not make an estimation about the effect of QDNC materials on the efficiency of the solar cells, and gives the same efficiency values for several QDNC solar cells with the same [Formula: see text]. The proposed modification, however, estimates a conversion efficiency in relation to the material properties and also the confinement type of the QDNCs. The results of the modified model show that, in contrast to the original one, the conversion efficiencies of different QDNC solar cells, even if they have the same [Formula: see text], become different depending upon the confinement type and shell material of the core/shell QDNCs, and this is crucial in the design and fabrication of the new generation solar cells to predict the confinement type and also appropriate QDNC materials for better efficiency.

Cap-shaped gastropods from Upper Jurassic and Lower Cretaceous deposits of northern East Siberia

NASA Astrophysics Data System (ADS)

Guzhov, A. V.; Zakharov, V. A.

2015-09-01

Cap-shaped gastropods are first identified in Upper Jurassic and Lower Cretaceous sections of northern East Siberia. They belong to three new genera of the subclass Pectinibranchia ( Boreioconus gen. nov., Nixepileolus gen. nov., and Taimyroconus gen. nov.), which are identified at the species level ( B. bojarkensis sp. nov., N. depressus sp. nov., T. zakharovi sp. nov.), and several species with the open nomenclature. The genus Taimyroconus attributed to the family Calyptraeidae is considered as an ancestral form of the genus Crepidula. The stratigraphic position of each taxon is determined for several sections. The facies confinement, habitat conditions, and ethology of defined genera are considered with the analysis of their geographic distribution.

Evolution of the eastern Austrian Molasse Basin: The Lower Miocene (Burdigalian) as a key to the understanding of the Eastern Alps - Molasse Basin system

NASA Astrophysics Data System (ADS)

Palzer, Markus; Knierzinger, Wolfgang; Wagreich, Michael; Meszar, Maria E.; Gier, Susanne; Soliman, Ali; -Elena Kallanxhi, Mǎdǎlina

2016-04-01

The eastern Austrian Molasse Basin is situated between the Bohemian Massif, the Waschberg-Zone and the Alps. There, sands of the Lower Miocene (Upper Ottnangian) Traisen Formation represent a clastic interval at the top of pelitic Schlier successions, which is correlated with the global sea level drop Bur3 (Burdigalian). North of the Danube River, the continuation of the Traisen-Formation is overlain by the Karpatian Laa-Formation. Drill cores from OMV-wells predominantly from the continuation of the Traisen Formation in deep parts in the NE of the basin show hundreds of meters of pelites with intersections of sands. Contrary to the exposed, mainly brackish TF, a turbiditic and predominantly fully marine deep-water environment is inferred from the cores. Profiles of carbonate content, XRD, XRF, whole rock chemistry, clay minerals, calcareous nannoplankton and dinoflagellate cysts of 7 wells were investigated representing a NE-SW transect through the LAMB. Based on these data, a new stratigraphy for the Burdigalian distal parts of the LAMB can be defined and correlated with the proximal units. The Traisen Formation and its equivalents are characterized at their base by an increased clastic input in the south and by increasing mica content in the northern parts. The complete interval is characterized by the decreased carbonate content. The XRD data show strongly reduced calcite contents which goe hand in hand with the absence of nannoplankton. Whether the signal is related to a crisis in primary production or to carbonate dissolution remains unclear. The absence of dinoflagellate cysts and the chemical data (reduced B/Al* ratios indicate reduced salinity) are considered as an argument for an environmental crisis. However, the absence of resedimented Cretaceous to Paleocene nannofossils, which usually occur together with the autochthonous NN4-nannofossils, indicates carbonate dissolution. These results enable us to define a basinal interval as equivalent to the proximal Traisen Formation which may serve as a key section for the stratigraphy of the deep basinal part. Sediments of this section were influenced by a low salinity crisis that was caused by the closure of the connection to the Upper Austrian Molasse Basin. This led to a partly or completely isolated basin in Lower Austria with a probably strongly reduced water circulation and strong freshwater influence. The closure is probably connected to the Miocene lateral extrusion of the Alps, the fast uplift of the Northern Calcareous Alps and accelerated sediment input from the south. This isolation may be terminated by the deepening of the Vienna Basin during Karpatian/Badenian times.

Spatially referenced statistical assessment of dissolved-solids load sources and transport in streams of the Upper Colorado River Basin

USGS Publications Warehouse

Kenney, Terry A.; Gerner, Steven J.; Buto, Susan G.; Spangler, Lawrence E.

2009-01-01

The Upper Colorado River Basin (UCRB) discharges more than 6 million tons of dissolved solids annually, about 40 to 45 percent of which are attributed to agricultural activities. The U.S. Department of the Interior estimates economic damages related to salinity in excess of $330 million annually in the Colorado River Basin. Salinity in the UCRB, as measured by dissolved-solids load and concentration, has been studied extensively during the past century. Over this period, a solid conceptual understanding of the sources and transport mechanisms of dissolved solids in the basin has been developed. This conceptual understanding was incorporated into the U.S. Geological Survey Spatially Referenced Regressions on Watershed Attributes (SPARROW) surface-water quality model to examine statistically the dissolved-solids supply and transport within the UCRB. Geologic and agricultural sources of dissolved solids in the UCRB were defined and represented in the model. On the basis of climatic and hydrologic conditions along with data availability, water year 1991 was selected for examination with SPARROW. Dissolved-solids loads for 218 monitoring sites were used to calibrate a dissolved-solids SPARROW model for the UCRB. The calibrated model generally captures the transport mechanisms that deliver dissolved solids to streams of the UCRB as evidenced by R2 and yield R2 values of 0.98 and 0.71, respectively. Model prediction error is approximated at 51 percent. Model results indicate that of the seven geologic source groups, the high-yield sedimentary Mesozoic rocks have the largest yield of dissolved solids, about 41.9 tons per square mile (tons/mi2). Irrigated sedimentary-clastic Mesozoic lands have an estimated yield of 1,180 tons/mi2, and irrigated sedimentary-clastic Tertiary lands have an estimated yield of 662 tons/mi2. Coefficients estimated for the seven landscape transport characteristics seem to agree well with the conceptual understanding of the role they play in the delivery of dissolved solids to streams in the UCRB. Predictions of dissolved-solids loads were generated for more than 10,000 stream reaches of the stream network defined in the UCRB. From these estimates, the downstream accumulation of dissolved solids, including natural and agricultural components, were examined in selected rivers. Contributions from each of the 11 dissolved-solids sources were also examined at select locations in the Grand, Green, and San Juan Divisions of the UCRB. At the downstream boundary of the UCRB, the Colorado River at Lees Ferry, Arizona, monitoring site, the dissolved-solids contribution of irrigated agricultural lands and natural sources were about 45 and 57 percent, respectively. Finally, model predictions, including the contributions of natural and agricultural sources for selected locations in the UCRB, were compared with results from two previous studies.

Controls on the accumulation of coal and on the development of anastomosed fluvial systems in the Cretaceous Dakota Formation of southern Utah

USGS Publications Warehouse

Kirschbaum, M.A.; McCabe, P.J.

1992-01-01

Alluvial strata of the Cretaceous Dakota Formation of southern Utah are part of a transgressive systems tract associated with a foreland basin developed adjacent to the Sevier orogenic belt. These strata contain valley fill deposits, anastomosed channel systems and widespread coals. The coals constitute a relatively minor part of the Dakota Formation in terms of sediment volume, but may represent a substantial amount of the time represented by the formation. The coals are separated by clastic units up to 20 m thick. The mires developed during periods when clastic influx was reduced either by high rates of subsidence close to the thrust belt or by deflection of rivers by emergent thrusts. -from Authors

Geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within northern Bexar and Comal Counties, Texas

USGS Publications Warehouse

Clark, Allan K.; Golab, James A.; Morris, Robert R.

2016-11-28

During 2014–16, the U.S. Geological Survey, in cooperation with the Edwards Aquifer Authority, documented the geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within northern Bexar and Comal Counties, Texas. The Edwards and Trinity aquifers are major sources of water for agriculture, industry, and urban and rural communities in south-central Texas. Both the Edwards and Trinity are classified as major aquifers by the State of Texas.The purpose of this report is to present the geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within northern Bexar and Comal Counties, Tex. The report includes a detailed 1:24,000-scale hydrostratigraphic map, names, and descriptions of the geology and hydrostratigraphic units (HSUs) in the study area.The scope of the report is focused on geologic framework and hydrostratigraphy of the outcrops and hydrostratigraphy of the Edwards and Trinity aquifers within northern Bexar and Comal Counties, Tex. In addition, parts of the adjacent upper confining unit to the Edwards aquifer are included.The study area, approximately 866 square miles, is within the outcrops of the Edwards and Trinity aquifers and overlying confining units (Washita, Eagle Ford, Austin, and Taylor Groups) in northern Bexar and Comal Counties, Tex. The rocks within the study area are sedimentary and range in age from Early to Late Cretaceous. The Miocene-age Balcones fault zone is the primary structural feature within the study area. The fault zone is an extensional system of faults that generally trends southwest to northeast in south-central Texas. The faults have normal throw, are en echelon, and are mostly downthrown to the southeast.The Early Cretaceous Edwards Group rocks were deposited in an open marine to supratidal flats environment during two marine transgressions. The Edwards Group is composed of the Kainer and Person Formations. Following tectonic uplift, subaerial exposure, and erosion near the end of Early Cretaceous time, the area of present-day south-central Texas was again submerged during the Late Cretaceous by a marine transgression resulting in deposition of the Georgetown Formation of the Washita Group.The Early Cretaceous Edwards Group, which overlies the Trinity Group, is composed of mudstone to boundstone, dolomitic limestone, argillaceous limestone, evaporite, shale, and chert. The Kainer Formation is subdivided into (bottom to top) the basal nodular, dolomitic, Kirschberg Evaporite, and grainstone members. The Person Formation is subdivided into (bottom to top) the regional dense, leached and collapsed (undivided), and cyclic and marine (undivided) members.Hydrostratigraphically the rocks exposed in the study area represent a section of the upper confining unit to the Edwards aquifer, the Edwards aquifer, the upper zone of the Trinity aquifer, and the middle zone of the Trinity aquifer. The Pecan Gap Formation (Taylor Group), Austin Group, Eagle Ford Group, Buda Limestone, and Del Rio Clay are generally considered to be the upper confining unit to the Edwards aquifer.The Edwards aquifer was subdivided into HSUs I to VIII. The Georgetown Formation of the Washita Group contains HSU I. The Person Formation of the Edwards Group contains HSUs II (cyclic and marine members [Kpcm], undivided), III (leached and collapsed members [Kplc,] undivided), and IV (regional dense member [Kprd]), and the Kainer Formation of the Edwards Group contains HSUs V (grainstone member [Kkg]), VI (Kirschberg Evaporite Member [Kkke]), VII (dolomitic member [Kkd]), and VIII (basal nodular member [Kkbn]).The Trinity aquifer is separated into upper, middle, and lower aquifer units (hereinafter referred to as “zones”). The upper zone of the Trinity aquifer is in the upper member of the Glen Rose Limestone. The middle zone of the Trinity aquifer is formed in the lower member of the Glen Rose Limestone, Hensell Sand, and Cow Creek Limestone. The regionally extensive Hammett Shale forms a confining unit between the middle and lower zones of the Trinity aquifer. The lower zone of the Trinity aquifer consists of the Sligo and Hosston Formations, which do not crop out in the study area.The upper zone of the Trinity aquifer is subdivided into five informal HSUs (top to bottom): cavernous, Camp Bullis, upper evaporite, fossiliferous, and lower evaporite. The middle zone of the Trinity aquifer is composed of the (top to bottom) Bulverde, Little Blanco, Twin Sisters, Doeppenschmidt, Rust, Honey Creek, Hensell, and Cow Creek HSUs. The underlying Hammett HSU is a regional confining unit between the middle and lower zones of the Trinity aquifer. The lower zone of the Trinity aquifer is not exposed in the study area.Groundwater recharge and flow paths in the study area are influenced not only by the hydrostratigraphic characteristics of the individual HSUs but also by faults and fractures and geologic structure. Faulting associated with the Balcones fault zone (1) might affect groundwater flow paths by forming a barrier to flow that results in water moving parallel to the fault plane, (2) might affect groundwater flow paths by increasing flow across the fault because of fracturing and juxtaposing porous and permeable units, or (3) might have no effect on the groundwater flow paths.The hydrologic connection between the Edwards and Trinity aquifers and the various HSUs is complex. The complexity of the aquifer system is a combination of the original depositional history, bioturbation, primary and secondary porosity, diagenesis, and fracturing of the area from faulting. All of these factors have resulted in development of modified porosity, permeability, and transmissivity within and between the aquifers. Faulting produced highly fractured areas that have allowed for rapid infiltration of water and subsequently formed solutionally enhanced fractures, bedding planes, channels, and caves that are highly permeable and transmissive. The juxtaposition resulting from faulting has resulted in areas of interconnectedness between the Edwards and Trinity aquifers and the various HSUs that form the aquifers.

Hydrogeologic Framework of the New Jersey Coastal Plain

USGS Publications Warehouse

Zapecza, Otto S.

1989-01-01

This report presents the results of a water-resources, oriented subsurface mapping program within the Coastal Plain of New Jersey. The occurrence and configuration of 15 regional hydrogeologic units have been defined, primarily on the basis of an interpretation of borehole geophysical data. The nine aquifers and six confining beds are composed of unconsolidated clay, silt, sand, and gravel and range in age from Cretaceous to Quaternary. Electric and gamma-ray logs from more than 1,000 Coastal Plain wells were examined. Of these, interpretive data for 302 sites were selected, on the basis of logged depth, quality of data, and data distribution, to prepare structure contour and thickness maps for each aquifer and a thickness map for each confining bed. These maps, together with 14 hydrogeologic sections, show the geometry, lateral extent, and vertical and horizontal relationships among the 15 hydrogeologic units. The hydrogeologic maps and sections show that distinct lower, middle, and upper aquifers are present within the Potomac, Raritan-Magothy aquifer system near the Delaware River from Burlington County to Salem County. Although the lower aquifer is recognized only in this area, the middle aquifer extends into the northeastern Coastal Plain of New Jersey, where it is stratigraphically equivalent to the Farrington aquifer. The upper aquifer extends throughout most of the New Jersey Coastal Plain and is stratigraphically equivalent to the Old Bridge aquifer in the northeastern Coastal Plain. The overlying Merchantville-Woodbury confining bed is the most regionally extensive confining bed within the New Jersey Coastal Plain. Its thickness ranges from less than 100 feet near the outcrop to more than 450 feet along the coast. The Englishtown aquifer system acts as a single aquifer throughout most of its subsurface extent, but it contains two water-bearing sands in pars of Monmouth and Ocean Counties. The overlying Marshalltown-Wenonah confining bed is a thin, leaky unit ranging in thickness from approximately 20 to 80 feet. The Wenonah-Mount Laurel aquifer is identified in the subsurface throughout the New Jersey Coastal Plain southeast of its outcrop area. Sediments that overlie the Wenonah-Mount Lauren aquifer and that are subjacent to the major aquifers within the Kirkwood Formation and the Cohansey Sand are described hydrologically as a composite confining bed. These include the Navesink Formation, Red Bank Sand, Tinton Sand, Hornerstown Sand, Vincentown Formation, Manasquan Formation, Shark River Formation, and Piney Point Formation and the basal clay of the Kirkwood Formation.. The Vincentown Formation functions as n aquifer within 3 to 10 miles downdip of its outcrop area. In areas farther downdip the Vincentown Formation functions as a confining bed. The Piney Point aquifer is laterally persistent from the southern New Jersey Coastal Plain northward into parts of Burlington and Ocean Counties. The Atlantic City 800-foot sand of the Kirkwood Formation can be recognized in the subsurface along coastal areas of Cape May, Atlantic, and southern Ocean Counties, but inland only as far west as the extent of the overlying confining bed. In areas west of the extent of the overlying confining bed, the Kirkwood Formation is in hydraulic connection with the overlying Cohansey Sand and younger surficial deposits and functions as an unconfined aquifer.

The QCD mass gap and quark deconfinement scales as mass bounds in strong gravity

NASA Astrophysics Data System (ADS)

Burikham, Piyabut; Harko, Tiberiu; Lake, Matthew J.

2017-11-01

Though not a part of mainstream physics, Salam's theory of strong gravity remains a viable effective model for the description of strong interactions in the gauge singlet sector of QCD, capable of producing particle confinement and asymptotic freedom, but not of reproducing interactions involving SU(3) color charge. It may therefore be used to explore the stability and confinement of gauge singlet hadrons, though not to describe scattering processes that require color interactions. It is a two-tensor theory of both strong interactions and gravity, in which the strong tensor field is governed by equations formally identical to the Einstein equations, apart from the coupling parameter, which is of order 1 {GeV}^{-1}. We revisit the strong gravity theory and investigate the strong gravity field equations in the presence of a mixing term which induces an effective strong cosmological constant, Λ f. This introduces a strong de Sitter radius for strongly interacting fermions, producing a confining bubble, which allows us to identify Λ f with the `bag constant' of the MIT bag model, B ˜eq 2 × 10^{14} {g} {cm}^{-3}. Assuming a static, spherically symmetric geometry, we derive the strong gravity TOV equation, which describes the equilibrium properties of compact hadronic objects. From this, we determine the generalized Buchdahl inequalities for a strong gravity `particle', giving rise to upper and lower bounds on the mass/radius ratio of stable, compact, strongly interacting objects. We show, explicitly, that the existence of the lower mass bound is induced by the presence of Λ _f, producing a mass gap, and that the upper bound corresponds to a deconfinement phase transition. The physical implications of our results for holographic duality in the context of the AdS/QCD and dS/QCD correspondences are also discussed.

Hydrogeology of the surficial and intermediate aquifer systems in Sarasota and adjacent counties, Florida

USGS Publications Warehouse

Barr, G.L.

1996-01-01

From 1991 to 1995, the hydrogeology of the surficial aquifer system and the major permeable zones and confining units of the intermediate aquifer system in southwest Florida was studied. The study area is a 1,400-square-mile area that includes Sarasota County and parts of Manatee, De Soto, Charlotte, and Lee Counties. Lithologic, geophysical, hydraulic property, and water-level data were used to correlate the hydrogeology and map the extent of the aquifer systems. Water chemistry was evaluated in southwest Sarasota County to determine salinity of the surficial and intermediate aquifer systems. The surficial aquifer is an unconfined aquifer system that overlies the intermediate aquifer system and ranges from a few feet to over 60 feet in thickness in the study area. Hydraulic properties of the surficial aquifer system determined from aquifer and laboratory tests, and model simulations vary considerably across the study area. The intermediate aquifer system, a confined aquifer system that lies between the surficial and the Upper Floridan aquifers, is composed of alternating confining units and permeable zones. The intermediate aquifer system has three major permeable zones that exhibit a wide range of hydraulic properties. Horizontal flow in the intermediate aquifer system is northeast to southwest. Most of the study area is in a discharge area of the intermediate aquifer system. Water ranges naturally from fresh in the surficial aquifer system and upper permeable zones of the intermediate aquifer system to moderately saline in the lower permeable zone. Water-quality data collected in coastal southwest Sarasota County indicate that ground-water withdrawals from major pumping centers have resulted in lateral seawater intrusion and upconing into the surficial and intermediate aquifer systems.

Hydrogeologic framework and ground-water resources at Seymour Johnson Air Force Base, North Carolina

USGS Publications Warehouse

Cardinell, A.P.; Howe, S.S.

1997-01-01

A preliminary hydrogeologic framework of the Seymour Johnson Air Force Base was constructed from published data, available well data, and reports from Air Base files, City of Goldsboro and Wayne County records, and North Carolina Geological Survey files. Borehole geophysical logs were run in selected wells; and the surficial, Black Creek, and upper Cape Fear aquifers were mapped. Results indicate that the surficial aquifer appears to have the greatest lateral variability of clay units and aquifer material of the three aquifers. A surficial aquifer water-level surface map, constructed from selected monitoring wells screened exclusively in the surficial aquifer, indicates the general direction of ground-water movement in this mostly unconfined aquifer is toward the Neuse River and Stoney Creek. However, water-level gradient data from a few sites in the surficial aquifer did not reflect this trend, and there are insufficient hydrologic and hydrogeologic data to determine the cause of these few anamalous measurements. The Black Creek aquifer underlies the surficial aquifer and is believed to underlie most of Wayne County, including the Air Base where the aquifer and overlying confining unit are estimated from well log data to be as much as 100 feet thick. The Black Creek confining unit ranges in thickness from less than 8 feet to more than 20 feet. There are currently no accessible wells screened exclusively in the Black Creek aquifer from which to measure water levels. The upper Cape Fear aquifer and confining unit are generally found at depths greater than 80 feet below land surface at the Air Base, and are estimated to be as much as 70 feet thick. Hydrologic and hydrogeologic data are insufficient to determine localized surficial aquifer hydrogeology, ground-water movement at several sites, or hydraulic head differences between the three aquifers.

Middle Triassic molluscan fossils of biostratigraphic significance from the Humboldt Range, northwestern Nevada

USGS Publications Warehouse

Silberling, Norman J.; Nichols, K.M.

1982-01-01

Cephalopods and bivalves of the genus Daonella occur at certain levels throughout the Middle Triassic section in the Humboldt Range, northwestern Nevada. These fossiliferous strata are assigned to the Fossil Hill Member and upper member of the Prida Formation, which here forms the oldest part of the Star Peak Group. The distribution and abundance of fossils within the section is uneven, partly because of original depositional patterns within the dominantly calcareous succession and partly because of diagenetic secondary dolomitization and hydrothermal metamorphism in parts of the range.Lower and middle Anisian fossil localities are restricted to the northern part of the range and are scattered, so that only three demonstrably distinct stratigraphic levels are represented. Cephalopods from these localities are characteristic of the Caurus Zone and typify the lower and upper parts of the Hyatti Zone, a new zonal unit whose faunas have affinity with those from the older parts of the Varium Zone in Canada.The upper Anisian and lowermost Ladinian, as exposed in the vicinity of Fossil Hill in the southern part of the range, are extremely fossiliferous. Cephalopod and Daonella shells form a major component of many of the limestone interbeds in the calcareous fine-grained clastic section here. Stratigraphically controlled bedrock collections representing at least 20 successive levels have been made from the Fossil Hill area, which is the type locality for the Rotelliformis, Meeki, and Occidentalis Zones of the upper Anisian and the Subasperum Zone of the lower Ladinian. Above the Subasperum Zone fossils are again scarce; upper Ladinian faunas representing the Daonella lommeli beds occur at only a few places in the upper member of the Prida Formation.Although unevenly fossiliferous, the succession of Middle Triassic cephalopod and Daonella faunas in the Humboldt Range is one of the most complete of any known in the world. Newly collected faunas from this succession provide the basis for revising the classic monograph on Middle Triassic marine invertebrates of North America published in 1914 by J. P. Smith and based largely on stratigraphically uncontrolled collections from the Humboldt Range. Taxonomic treatment of these collections, old and new, from the Humboldt Range provides the documentation necessary to establish this Middle Triassic succession as a biostratigraphic standard of reference.Of the 68 species of ammonites described or discussed, 4 are from the lower Anisian, 20 from the middle Anisian, 39 from the upper Anisian, 4 from the lower Ladinian, and 1 from the upper Ladinian. A few additional ammonite species from other localities in Nevada are also treated in order to clarify their morphologic characteristics and stratigraphic occurrence. Other elements in the Middle Triassic molluscan faunas of the Humboldt Range comprise five species of nautiloids and three of coleoids from the middle and upper Anisian parts of the section. Eight more or less stratigraphically restricted species of Daonella occur in the upper Anisian and Ladinian.

The combined use of 87Sr/86Sr and carbon and water isotopes to study the hydrochemical interaction between groundwater and lakewater in mantled karst

USGS Publications Warehouse

Katz, B.G.; Bullen, T.D.

1996-01-01

The hydrochemical interaction between groundwater and lakewater influences the composition of water that percolates downward from the surficial aquifer system through the underlying intermediate confining unit and recharges the Upper Floridan aquifer along highlands in Florida. The 87Sr/86Sr ratio along with the stable isotopes, D, 18O, and 13C were used as tracers to study the interaction between groundwater, lakewater, and aquifer minerals near Lake Barco, a seepage lake in the mantled karst terrane of northern Florida. Upgradient from the lake, the 87Sr/86Sr ratio of groundwater decreases with depth (mean values of 0.71004, 0.70890, and 0.70852 for water from the surficial aquifer system, intermediate confining unit, and Upper Floridan aquifer, respectively), resulting from the interaction of dilute oxygenated recharge water with aquifer minerals that are less radiogenic with depth. The concentrations of Sr2+ generally increase with depth, and higher concentrations of Sr2+ in water from the Upper Floridan aquifer (20-35 ??g/L), relative to water from the surficial aquifer system and the intermediate confining unit, result from the dissolution of Sr-bearing calcite and dolomite in the Eocene limestone. Dissolution of calcite [??13C = -1.6 permil (???)] is also indicated by an enriched ??13CDIC (-8.8 to - 11.4???) in water from the Upper Floridan aquifer, relative to the overlying hydrogeologic units (??13CDIC < - 16???). Groundwater downgradient from Lake Barco was enriched in 18O and D relative to groundwater upgradient from the lake, indicating mixing of lakewater leakage and groundwater. Downgradient from the lake, the 87Sr/86Sr ratio of groundwater and aquifer material become less radiogenic and the Sr2+ concentrations generally increase with depth. However, Sr2+ concentrations are substantially less than in upgradient groundwaters at similar depths. The lower Sr2+ concentrations result from the influence of anoxic lakewater leakage on the mobility of Sr2+ from clays. Based on results from mass-balance modeling, it is probable that cation exchange plays the dominant role in controlling the 87Sr/86Sr ratio of groundwater, both upgradient and downgradient from Lake Barco. Even though groundwater from the three distinct hydrogeologic units displays considerable variability in Sr concentration and isotopic composition, the dominant processes associated with the mixing of lakewater leakage with groundwater, as well as the effects of mineral-water interaction, can be ascertained by integrating the use of stable and radiogenic isotopic measurements of groundwater, lakewater, and aquifer minerals.

Overview of long pulse H-mode operation on EAST

NASA Astrophysics Data System (ADS)

Gong, X.; Garofalo, A. M.; Wan, B.; Li, J.; Qian, J.; Li, E.; Liu, F.; Zhao, Y.; Wang, M.; Xu, H.; EAST Team

2017-10-01

The EAST research program aims to demonstrate steady-state long-pulse high-performance H-mode operations with ITER-like poloidal configuration and RF-dominated heating schemes. In the recent experimental campaign, a long pulse fully non-inductive H-mode discharge lasting over 100 seconds using the upper ITER-like tungsten divertor has been achieved in EAST. This scenario used only RF heating and current drive, but also benefitted from an integrated control of the wall conditioning, plasma configuration, divertor heat flux, particle exhaust, impurity management and superconducting coils safety. Maintaining effective coupling of multiple RF heating and current drive sources on EAST is a critical ingredient. This long pulse discharge had good energy confinement, H98,y2 1.1-1.2, and all of the plasma parameters reach a true steady-state. Power balance indicates that the confinement improvement is due partly to a significantly reduced core electron transport inside minor radius rho<0.4. This work was supported by the National Magnetic Confinement Fusion Program of China Contract No. 2015GB10200 and the US Department of Energy Contract No. DE-SC0010685.

Hot-water aquifer storage: A field test

NASA Astrophysics Data System (ADS)

Parr, A. D.; Molz, F. J.; Andersen, P. F.

1980-03-01

The basic water injection cycle used in a large-scale field study of heat storage in a confined aquifer near Mobile, Alabama is described. Water was pumped from an upper semi-confined aquifer, passed through a boiler where it was heated to a temperature of about 55 C, and injected into a medium sand confined aquifer. The injection well has a 6-inch (15-cm) partially-penetrating steel screen. The top of the storage formation is about 40 meters below the surface and the formation thickness is about 21 meters. In the first cycle, after a storage period of 51 days, the injection well was pumped until the temperature of the recovered water dropped to 33 c. At that point 55,300 cubic meters of water had been withdrawn and 66 percent of the injected energy had been recovered. The recovery period for the second cycle continued until the water temperature was 27.5 C and 100,100 cubic meters of water was recovered. At the end of the cycle about 90 percent of the energy injected during the cycle had been recovered.

Hydrogeologic framework, groundwater and surface-water systems, land use, pumpage, and water budget of the Chamokane Creek basin, Stevens County, Washington

USGS Publications Warehouse

Kahle, Sue C.; Taylor, William A.; Lin, Sonja; Sumioka, Steven S.; Olsen, Theresa D.

2010-01-01

A study of the water resources of the unconsolidated groundwater system of the Chamokane Creek basin was conducted to determine the hydrogeologic framework, interactions of shallow and deep parts of the groundwater system with each other and the surface-water system, changes in land use and land cover, and water-use estimates. Chamokane Creek basin is a 179 mi2 area that borders and partially overlaps the Spokane Indian Reservation in southern Stevens County in northeastern Washington State. Aquifers within the Chamokane Creek basin are part of a sequence of glaciofluvial and glaciolacustrine sediment that may reach total thicknesses of about 600 ft. In 1979, most of the water rights in the Chamokane Creek basin were adjudicated by the United States District Court requiring regulation in favor of the Spokane Tribe of Indians' senior water right. The Spokane Tribe, the State of Washington, and the United States are concerned about the effects of additional groundwater development within the basin on Chamokane Creek. Information provided by this study will be used to evaluate the effects of potential increases in groundwater withdrawals on groundwater and surface-water resources within the basin. The hydrogeologic framework consists of six hydrogeologic units: The Upper outwash aquifer, the Landslide Unit, the Valley Confining Unit, the Lower Aquifer, the Basalt Unit, and the Bedrock Unit. The Upper outwash aquifer occurs along the valley floors of the study area and consists of sand, gravel, cobbles, boulders, with minor silt and (or) clay interbeds in places. The Lower aquifer is a confined aquifer consisting of sand and gravel that occurs at depth below the Valley confining unit. Median horizontal hydraulic conductivity values for the Upper outwash aquifer, Valley confining unit, Lower aquifer, and Basalt unit were estimated to be 540, 10, 19, and 3.7 ft/d, respectively. Many low-flow stream discharge measurements at sites on Chamokane Creek and its tributaries were at or near zero flow. The most notable exception is where Chamokane Creek is supported by discharge of large springs from the Upper outwash aquifer in the southern part of the basin. Most high-flow measurements indicated gains in streamflow (groundwater discharging to the stream). Large streamflow losses, however, were recorded near the north end of Walkers Prairie where streamflow directly recharges the Upper outwash aquifer. The similarity in seasonal water-level fluctuations in the Upper outwash aquifer and the Lower aquifer indicate that these systems may be fairly well connected. Land use and land cover change analysis indicates that Chamokane Creek basin has been dominated by forests with some pasture and agricultural lands with sparse residential development from the 1980s to present. Loss in forest cover represents the largest change in land cover in the basin between 1987 and 2009. This appears to be mostly due to forestry activities, especially in the northern part of the basin. Since 1987, more than 18,000 acres of evergreen forest have been logged and are at various stages of regrowth. Estimated average annual total groundwater pumpage in the basin increased from 224 million gallons per year (Mgal/yr) in 1980 to 1,330 Mgal/yr in 2007. The largest withdrawals during 2007 were to supply two fish hatcheries, with a combined total annual pumpage of about 1,150 Mgal. Annual groundwater pumpage values from 1980 through 2007 for the study area ranged from 21.1 to 28.9 Mgal/yr for domestic wells and 0.38 to 23.7 Mgal/yr for public supply. An approximate water budget for a typical year in the Chamokane Creek basin indicates that 19.6 in. of precipitation are balanced by 4.7 in. of streamflow discharge from the basin, and 14.9 in. of evapotranspiration.

Hydrogeologic framework, hydrology, and refined conceptual model of groundwater flow for Coastal Plain aquifers at the Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2005-12

USGS Publications Warehouse

Brayton, Michael J.; Cruz, Roberto M.; Myers, Luke; Degnan, James R.; Raffensperger, Jeff P.

2015-01-01

The regional hydrogeologic framework indicates that the site is underlain by Coastal Plain sediments of the Columbia, Merchantville, and Potomac Formations. Two primary aquifers underlying the site, the Columbia and the upper Potomac, are separated by the Merchantville Formation confining unit. Local groundwater flow in the surficial (Columbia) aquifer is controlled by topography and generally flows northward and discharges to nearby surface water. Regional flow within the Potomac aquifer is towards the southeast, and is strongly influenced by major water withdrawals locally. Previous investigations at the site indicated that contaminants, primarily benzene and chlorinated benzene compounds, were present in the Columbia aquifer in most locations; however, there were only limited detections in the upper Potomac aquifer as of 2004. From 2005 through 2012, the USGS designed a monitoring network, assisted with exploratory drilling, collected data at monitoring wells, conducted geophysical surveys, evaluated water-level responses in wells during pumping of a production well, and evaluated major aquifer withdrawals. Data collected through these efforts were used to refine the local conceptual flow system. The refined conceptual flow system for the site includes: (a) identification of gaps in confining units in the study area, (b) identification and correlation of multiple water-bearing sand intervals within the upper Potomac Formation, (c) connections between groundwater and surface water, (d) connections between shallow and deeper groundwater, (e) new water-level (or potentiometric surface) maps and inferred flow directions, and (f) identification of major local pumping well influences. The implications of the revised conceptual flow system on the occurrence and movement of site contaminants are that the resulting detection of contaminants in the upper Potomac aquifer at specific well locations can be attributed primarily to either advective lateral transport, direct vertical contaminant transport, or a combination of vertical and lateral movement resulting from changes in water withdrawal rates over time.

Geologic structure and altitude of the top of the Minnelusa Formation, northern Black Hills, South Dakota and Wyoming, and Bear Lodge Mountains, Wyoming

USGS Publications Warehouse

Peter, Kathy D.; Kyllonen, David P.; Mills, K.R.

1987-01-01

Beginning in 1981, a 3-yr project was conducted to determine the availability and quality of groundwater in the sedimentary bedrock aquifers in the Black Hills of South Dakota and Wyoming. The project was limited to three bedrock units in order of increasing age: the Cretaceous Inyan kara Group, Permian and Pennsylvanian Minnelusa Formation, and Mississippian Madison (or Pahasapa) Limestone. This map shows the altitude of the top of the Minnelusa Formation in the northern Black Hills, and shows the configuration of the structural features in the northern part of the Black Hills and the eastern part of the Bear Lodge Mountains. In general, the Minnelusa Formation dips away from the Black Hills uplift, either to the northeast and the Williston Basin or, south of the Bear Lodge Mountains, to the southwest and the Powder River basin, which is outside the map area. In the map area, the upper beds of the Minnelusa Formation are an aquifer and the lower beds are a confining or semi-confining unit. The upper part of the Minnelusa Formation has a greater percentage of coarse-grained sandstone beds than the lower part. Furthermore, solution and removal of anhydrite, brecciation, and solution of cement binding the sandstone grains may have increased the permeability of the upper part of the Minnelusa Formation in the Black Hills. Wells completed in the upper part of the Minnelusa have yields that exceed 100 gal/min in some areas and at least one large diameter well is reported to flow 1,000 gal/min in some areas and at least one large diameter well is reported to flow 1,000 gal/min. Flowing wells have been completed in the Minnelusa aquifer in most of the study area in South Dakota and in about the northern one-half of Crook County, Wyoming. (Lantz-PTT)

Genomic Biomarkers for the Prediction of Stage and Prognosis of Upper Tract Urothelial Carcinoma.

PubMed

Bagrodia, Aditya; Cha, Eugene K; Sfakianos, John P; Zabor, Emily C; Bochner, Bernard H; Al-Ahmadie, Hikmat A; Solit, David B; Coleman, Jonathan A; Iyer, Gopa; Scott, Sasinya N; Shah, Ronak; Ostrovnaya, Irina; Lee, Byron; Desai, Neil B; Ren, Qinghu; Rosenberg, Jonathan E; Dalbagni, Guido; Bajorin, Dean F; Reuter, Victor E; Berger, Michael F

2016-06-01

Genomic characterization of radical nephroureterectomy specimens in patients with upper tract urothelial carcinoma may allow for thoughtful integration of systemic and targeted therapies. We sought to determine whether genomic alterations in upper tract urothelial carcinoma are associated with adverse pathological and clinical outcomes. Next generation exon capture sequencing of 300 cancer associated genes was performed in 83 patients with upper tract urothelial carcinoma. Genomic alterations were assessed individually and also grouped into core signal transduction pathways or canonical cell functions for association with clinicopathological outcomes. Binary outcomes, including grade (high vs low), T stage (pTa/T1/T2 vs pT3/T4) and organ confined status (pT2 or less and N0/Nx vs greater than pT2 or N+) were assessed with the Kruskal-Wallis and Fisher exact tests as appropriate. Associations between alterations and survival were estimated using the Kaplan-Meier method and Cox regression. Of the 24 most commonly altered genes in 9 pathways TP53/MDM2 alterations and FGFR3 mutations were the only 2 alterations uniformly associated with high grade, advanced stage, nonorgan confined disease, and recurrence-free and cancer specific survival. TP53/MDM2 alterations were associated with adverse clinicopathological outcomes whereas FGFR3 mutations were associated with favorable outcomes. We created a risk score using TP53/MDM2 and FGFR3 status that was able to discriminate between adverse pathological and clinical outcomes, including in the subset of patients with high grade disease. The study is limited by small numbers and lack of validation. Our data indicate that specific genomic alterations in radical nephroureterectomy specimens correlate with tumor grade, stage and cancer specific survival outcomes. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Life threatening angioedema in a patient on ACE inhibitor (ACEI) confined to the upper airway

PubMed Central

Tharayil, Abdulgafoor Muslim; Chanda, Arshad Hussain; Shiekh, Hakim Ahmad; Elkhatib, Mohamed Saad; Nayeemuddin, Mohammed; Alshamandy, Abdelhafiz Ali Ahmed

2014-01-01

Introduction: ACE inhibitors accounts for 8% of all cases of angioneurotic edema and the overall incidence is 0.1 to 0.7% of patients on ACE inhibitors. It is a leading cause (20-40%) of emergency room visits in the US with angioedema. We report a case of angioedema caused by ACE inhibitors confined to the upper airway after four years on treatment with Lisinopril which persisted for three weeks and required endotracheal intubation and subsequent tracheostomy due to delayed resolution. This case is one of the rare cases presented as upper airway edema which persisted for a long time. Presentation: A 60-year-old Sudanese male patient with osteoarthritis in both knees underwent bilateral total knee replacement under single-shot epidural anesthesia. He had significant past medical history of type II diabetes, bipolar affective disorder and hypertension managed with Lisinopril for the past four years. Postoperatively after 10 hours the patient desaturated and developed airway obstruction requiring intubation. Laryngoscopy revealed an edematous tongue and upper airway and vocal cords were not visualized. In view of this clinical picture a provisional diagnosis of angioedema secondary to Lisinopril was made and it was discontinued. CT scan of the neck and soft tissues revealed severe airway edema with snugly fitting endotracheal tube with no peritubal air. A repeat CT neck on the tenth postoperative day showed no signs of resolution and an elective tracheostomy was performed on the eleventh postoperative day. C1 inhibitor protein and C4 levels were assayed to exclude hereditary angioedema and were found to be within normal range. Decannulation of tracheostomy was done after airway edema resolved on the twenty-fourth postoperative day as confirmed by CT scan. Subsequently he was transferred to the ward and discharged home. Conclusion: ACEI induced angioedema is a well-recognized condition. Early diagnosis based on a high index of suspicion, immediate withdrawal of the offending drug followed by supportive therapy is the cornerstone of management. PMID:25745598

Effects of groundwater flow on the distribution of biogenic gas in parts of the northern Great Plains of Canada and United States

USGS Publications Warehouse

Anna, Lawrence O.

2011-01-01

Parts of the northern Great Plains in eastern Montana and western North Dakota and southeastern Alberta and southwestern Saskatchewan, Canada, were studied as part of an assessment of shallow biogenic gas in Upper Cretaceous rocks.Parts of the northern Great Plains in eastern Montana and western North Dakota and southeastern Alberta and southwestern Saskatchewan, Canada, were studied as part of an assessment of shallow biogenic gas in Upper Cretaceous rocks. Large quantities of shallow biogenic gas are produced from low-permeability, Upper Cretaceous reservoirs in southeastern Alberta and southwestern Saskatchewan, Canada. Rocks of similar types and age produce sparingly in the United States except on large structures, such as Bowdoin dome and Cedar Creek anticline. Significant production also occurs in the Tiger Ridge area, where uplift of the Bearpaw Mountains created stratigraphic traps. The resource in Canada is thought to be a continuous, biogenic-gas-type accumulation with economic production in a variety of subtle structures and stratigraphic settings. The United States northern Great Plains area has similar conditions but only broad structural closures or stratigraphic traps associated with local structure have produced economically to date. Numerical flow modeling was used to help determine that biogenic gas in low-permeability reservoirs is held in place by high hydraulic head that overrides buoyancy forces of the gas. Modeling also showed where hydraulic head is greater under Tertiary capped topographic remnants rather than near adjacent topographic lows. The high head can override the capillary pressure of the rock and force gas to migrate to low head in topographically low areas. Most current biogenic gas production is confined to areas between mapped lineaments in the northern Great Plains. The lineaments may reflect structural zones in the Upper Cretaceous that help compartmentalize reservoirs and confine gas accumulations.

Potentiometric surface of the intermediate aquifer system, west- central Florida, May 1987

USGS Publications Warehouse

Lewelling, B.R.

1988-01-01

The intermediate aquifer system within the Southwest Florida Water Management District underlies a 5,000 sq mi area of De Soto, Sarasota, Hardee, Manatee, and parts of Charlotte, Hillsborough, Highlands, and Polk Counties. The intermediate aquifer system occurs between the overlying surficial aquifer system and the underlying Floridan aquifer system, and consists of layers of sand, shell, clay, marl, limestone, and dolom of the Tamiami, Hawthorn, and Tampa Formations of late Tertiary age. The intermediate aquifer system contains one or more water-bearing units separated by discontinuous confining units. This aquifer system is the principal source of potable water in the southwestern part of the study area and is widely used as a source of water in other parts where wells are open to the intermediate aquifer system or to both the intermediate and Floridan aquifer systems. Yields of individual wells open to the intermediate aquifer system range from a few gallons to several hundred gallons per minute. The volume of water withdrawn from the intermediate aquifer system is considerably less than that withdrawn from the Floridan aquifer system in the study area. The surface was mapped by determining the altitude of water levels in a network of wells and is represented on maps by contours that connect points of equal altitude. The compos potentiometric surface of all water-bearing units within the intermediate aquifer system is shown. In areas where multiple aquifers exist, wells open to all aquifers were selected for water level measurements whenever possible. In the southwestern and lower coastal region of the study area, two aquifers and confining units are described for the intermediate aquifer system: the Tamiami-upper Hawthorn aquifer and the underlying lower Hawthorn-upper Tampa aquifer. The potentiometric surface of the Tamiami-upper Hawthorn aquifer is also shown. Water levels are from wells drilled and open exclusively to that aquifer. The exact boundary for the Tamiami-upper Hawthorn aquifer is undetermined because of limd geohydrologic data available from wells. (Lantz-PTT)

Evolution of a Miocene sag basin in the Alboran Sea

NASA Astrophysics Data System (ADS)

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

2012-04-01

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

Geology of Mount Rainier National Park, Washington

USGS Publications Warehouse

Fiske, Richard S.; Hopson, Clifford Andrae; Waters, Aaron Clement

1963-01-01

Mount Rainier National Park includes 378 square miles of rugged terrain on the west slope of the Cascade Mountains in central Washington. Its mast imposing topographic and geologic feature is glacier-clad Mount Rainier. This volcano, composed chiefly of flows of pyroxene andesite, was built upon alt earlier mountainous surface, carved from altered volcanic and sedimentary rocks invaded by plutonic and hypabyssal igneous rocks of great complexity. The oldest rocks in the park area are those that make up the Olmnapecosh Formation of late Eocene age. This formation is more than 10,000 feet thick, and consists almost entirely of volcanic debris. It includes some lensoid accumulations of lava and coarse mudflows, heaped around volcanic centers., but these are surrounded by vastly greater volumes of volcanic clastic rocks, in which beds of unstratified coarse tuff-breccia, about 30 feet in average thickness, alternate with thin-bedded breccias, sandstones, and siltstones composed entirely of volcanic debris. The coarser tuff-breccias were probably deposited from subaqueous volcanic mudflows generated when eruption clouds were discharged directly into water, or when subaerial ash flows and mudflows entered bodies of water. The less mobile mudflows and viscous lavas built islands surrounded by this sea of thinner bedded water-laid clastics. In compostion the lava flows and coarse lava fragments of the Ohanapecosh Formation are mostly andesite, but they include less abundant dacite, basalt, and rhyolite. The Ohanapecosh Formation was folded, regionally altered to minerals characteristic of the zeolite facies of metamorphism, uplifted, and deeply eroded before the overlying Stevens Ridge Formation of Oligocene or early Miocene age was deposited upon it. The Stevens Ridge rocks, which are about 3,000 feet in maximum total thickness, consist mainly of massive ash flows. These are now devitrified and altered, but they originally consisted of rhyodacite pumice lapilli and glass shards, which compacted and welded into thick massive units during emplacement and cooling. Subordinate water-laid clastic rocks occur t(ward the top of the formation, and thin-bedded pyroclastic layers occur between some of the ash flows. Exposures on Backbone Ridge and on Carbon River below the mouth of Cataract Creek show that in places the thick basal Stevens Ridge ash flows swept with great violence over an old erosion surface developed on rocks of the Ohanapecosh Formation. Masses of mud, tree trunks, and other surface debris were swirled upward into the base of the lowermost ash fiery, and lobes and tongues of hot ash were forced downward into. the saprolitic mud. The Stevens Ridge Formation is concordantly overlain by the Fifes Peak Formation of probable early Miocene age, which consists of lava flows, subordinate mudflows, and minor quantities of tuffaceous clastic rocks. The lavas are predominantly olivine basalt and basaltic andesite, but they include a little rhyolite. They are slightly to moderately altered: the ferromagnesian phenocrysts are generally replaced by saponite, chiprite, or carbonate ; the glass is devitrified ; and the rocks are locally permeated by veinlets of zeolite. Swarms of diabase sills and dikes are probably intrusive equivalents of the Fifes Peak lavas. The upper part of the Fifes Peak Formation has been mostly eroded from Mount Rainier National Park, but farther north, in the Cedar Lake quadrangle, it attains a thickness of more than 5,000 feet. The Fifes Peak and earlier formations were gently folded, faulted, uplifted, and eroded before the. late Miocene Tatoosh pluton worked its way upward to shallow depths and eventually broke through to the surface. The rise of the pluton was accompanied by .the injection of a complicated melange of satellitic stocks, sills, and dikes. A favored horizon for intrusion of sills was along or near the unconfo

Red River of the North, Reconnaissance Report: Main Stem Subbasin.

DTIC Science & Technology

1980-12-01

total subbasin land area. The bottomland hardwood forests which survived agricultural land clearing operations are confined today to corridors along...impair many of its uses such as recreation, 16 stock watering, and fish and wildife propagation (North Dakota Public Health Service, 1978; Upper... corridor for animals moving north and south along the Red River. Forests afford breeding and nesting areas for birds and rank second only 2to wetlands

Nimrod Lake, An Archeological Survey of a Reservoir Drawdown.

DTIC Science & Technology

1978-01-01

nomadic bands hunted late Pleistocene megafauna (e.g., mammoths, mastodons, bison and smaller game) and also gathered wild plant foods. The most...primary exploitation of Pleistocene megafauna , in particular the bison, to subsistence strategies exercising more variation in faunal and floral...a- the upper end of the reservoir where the reservoir is confined to the river channel and the gradient is much steeper, other factors in addition to

Tree shaking machine aids cone collection in a Douglas-fir seed orchard.

Treesearch

Donald L. Copes; William K. Randall

1983-01-01

A boom-type tree shaker was used in a Douglas-fir seed orchard to remove cones from 7- to 9-meter tall grafted Douglas-fir trees. An average of 55 percent of the cones were removed by shaking, while damage inflicted to the upper crown was confined primarily to branch and leader breakage in the top three internodes. Damage to the lower bole, where the shaker head...

Hydrogeology of the Sarasota-Port Charlotte area, Florida

USGS Publications Warehouse

Wolansky, R.M.

1983-01-01

The surficial and intermediate aquifers are the major source of public water supplies in the Sarasota-Port Charlotte, Florida, area because of the relatively poor quality of Floridan aquifer water. The hydrogeologic framework consists of the surficial aquifer, intermediate aquifers (Tamiami-upper Hawthorn and lower Hawthorn-upper Tampa aquifers) and confining beds, Floridan aquifer, and lower confining bed (or base of the Floridan aquifer). The quality of ground water in the surficial and intermediate aquifers is generally good, except in the western (coastal) and southern parts where saltwater intrusion or incomplete flushing of connate water has occurred. The mineral content of ground water generally increases with depth and areally from the northeast towards the west and south. A water budget for the study area shows that an average annual rainfall of 51.0 inches minus an evapotranspiration of 38.0 inches per year and streamflow of 12.5 inches per year leaves 0.5 inch per year of recharge to the surficial aquifer. Combined pumpage from the aquifers is 1.06 inches per year. A preliminary quasi-time dimensional model has been applied to the study area to check the reasonableness of the hydrogeologic framework defined and of aquifer parameters. The model was considered calibrated when the final head matrix was within plus or minus 5 feet of the starting head. (USGS)

Deep-sea tsunami deposits in the Miocene Nishizaki Formation of Boso Peninsula, Central Japan

NASA Astrophysics Data System (ADS)

Lee, I. T.; Ogawa, Y.

2003-12-01

Many sets of deep-sea deposits considered to be formed by return flow of tsunami were found from the middle Miocene Nishizaki Formation of Boso Peninsula, Central Japan, which is located near the convergent plate boundary at present as well as in the past, and has been frequently attacked by tsunami. The characteristics of the tsunami deposits in the Nishizaki Formation are as follows. Each set consists of 10-20 beds with parallel laminations formed under upper plane regime composed of alternated pumiceous beds in white and black colors. The white bed comprises coarse sands and pebbles with thickness of 5-10 cm. In contrast, the black bed is made of silts with thickness less than 1 cm. Among the 10-20 beds, the grain size is coarsest in the middle part of the set in general. The uppermost bed of each set shows cross-lamination formed by lower plane regime, gradually changing into finer graded bed on top. Sometimes, the lower part of the parallel laminated bed is associated with an underlying debrite or turbidite bed. Each set of these parallel-laminated beds is lenticular in shape thinning to the east in consistent with the generally eastward paleocurrent of the cross-lamination at the top. Such sedimentary characteristics are different from any event deposits reported in deep-sea but similar to the deep-sea K/T boundary deposits in the Caribbean region. Statistically, tsunami waves occur totally 12-13 times. Among them the height of 5-6th wave is known to be strongest. Interval time of each return flow is known to be 30-40 minutes, enough to settle the finer clastics at each bed top. The parallel-laminated parts have common dish structure and never trace fossils, indicating rather rapid deposition for the whole parts of the set. Consequently, the sedimentary characteristics shown from the parallel-laminated beds of the Nishizaki Formation are attributed to the return flow of tsunami to the deep-sea. We considered that such deep-sea parallel-laminated deposits of pumiceous clastics occur just after a large earthquake which forms the debrite or turbidite at the lowermost part.

Tectonic and climatic controls on continental depositional facies in the Karoo Basin of northern Natal, South Africa

NASA Astrophysics Data System (ADS)

Turner, Brian R.

1986-02-01

The eastern Karoo Basin, South Africa, contains a thick sequence of terrigenous clastic sediments comprising a meanderbelt facies, braided channel facies divided into coarse and fine subfacies, fluviolacustrine facies and aeolian facies. Depositional trends and changes in fluvial style reflect a progressive increase in aridity of the climate under stable tectonic conditions, interrupted by two phases of source area tectonism and the development of fine and coarse clastic wedges of the braided channel subfacies; the latter signifying a short interlude of cool, wet conditions. The fine braided channel subfacies occurs in the upper part of the meanderbelt facies, which was deposited by ephemeral, meandering mixed-load streams of variable discharge and sinuosity, under dry, semi-arid climatic conditions. These deposited complex, internally discordant channel sands and well-developed levee deposits. Following deposition of the coarse braided channel subfacies semi-arid conditions returned and fluvial deposition was dominated by ephemeral, straight to slightly sinuous mixed load streams characterised by simple channel sand bodies. As the aridity of the climate increased, the streams became more localised and carried an increasing proportion of fines. Interbedded with and overlying the fluvial deposits is a mudstone-dominated lacustrine sequence grading up into aeolian sands suggesting a playa lake-type situation. The general absence of evaporites from these sediments is attributed to the fresh nature of the lake waters, as evidenced by the freshwater aquatic organisms and clay-mineral suite, the lack of adequate inflow for solute accumulation and the removal of dust impregnated by salts from the surface of the dry lake bed during the dry season by superheated, upward-spiralling columns of air. Broadly similar environments to the fluvio-lacustrine and aeolian facies sequence are to be found in the Lake Eyre Basin of central Australia and the Okavango "delta" of northern Botswana. The Okavango "delta" model has an important bearing on patterns of fluvial sedimentation in arid regions since it shows many characteristics of temperate, well-vegetated anastomosed fluvial systems despite its location in the Kalahari Desert.

Growth of the Zagros Fold-Thrust Belt and Foreland Basin, Northern Iraq, Kurdistan

NASA Astrophysics Data System (ADS)

Koshnaw, Renas; Horton, Brian; Stockli, Daniel; Barber, Douglas; Ghalib, Hafidh; Dara, Rebwar

2016-04-01

The Zagros orogenic belt in the Middle Eastern segment of the Alpine-Himalayan system is among the youngest seismically active continental collision zones on Earth. However, due to diachronous and incremental collision, the precise ages and kinematics of shortening and deposition remain poorly understood. The Kurdistan region of the Zagros fold-thrust belt and foreland basin contains well-preserved Neogene wedge-top and foredeep deposits that include clastic nonmarine fill of the Upper Fars, Lower Bakhtiari, and Upper Bakhtiari Formations. These deposits record significant information about orogenic growth, fold-thrust dynamics, and advance of the deformation front. Thermochronologic and geochronologic data from thrust sheets and stratigraphic archives combined with local earthquake data provide a unique opportunity to address the linkages between surface and subsurface geologic relationships. This research seeks to constrain the timing and geometry of exhumation and deformation by addressing two key questions: (1) Did the northwestern Zagros fold-thrust belt evolve from initial thin-skinned shortening to later thick-skinned deformation or vice-versa? (2) Did the fold-thrust belt advance steadily under critical/supercritical wedge conditions involving in-sequence thrusting or propagate intermittently under subcritical conditions with out-of-sequence deformation? From north to south, apatite (U-Th)/He ages from the Main Zagros Thrust, the Mountain Front Flexure (MFF), and additional frontal thrusts suggest rapid exhumation by ~10 Ma, ~5 Ma, and ~8 Ma respectively. Field observations and seismic sections indicate progressive tilting and development of growth strata within the Lower Bakhtiari Formation adjacent to the frontal thrusts and within the Upper Bakhtiari Formation near the MFF. In the Kurdistan region of Iraq, a regional balanced cross section constrained by new thermochronometric results, proprietary seismic reflection profiles, and earthquake hypocenters suggest prolonged thin-skinned shortening in sequence from north to south followed by a thick-skinned out-of-sequence MFF deformation and intermittent hinterland uplift postdating initial collision. Magnetostratigraphic analyses of Dinarta wedge-top deposits and Kifri foredeep deposits constrain accumulation of the Upper Fars-Lower Bakhtiari synorogenic succession to 12.5-5 Ma. These findings suggest that temporal and spatial shifts in upper-crustal modes of deformation in the Kurdistan segment of the Zagros orogenic belt strongly influenced patterns of topographic growth, landscape development, and resulting foreland basin stratigraphy.

Pre-lithification tectonic foliation development in a clastic sedimentary rock sequence from SW Ireland

NASA Astrophysics Data System (ADS)

Meere, Patrick; Mulchrone, Kieran; McCarthy, David

2017-04-01

The current orthodoxy regarding the development of regionally developed penetrative tectonic cleavage fabrics in sedimentary rocks is that it postdates lithification of those rocks. It is well established that fabric development under these circumstances is achieved by a combination of grain rigid body rotation, crystal-plastic deformation and pressure solution. The latter is believed to be the primary mechanism responsible for the domainal nature of cleavage development commonly observed in low grade metamorphic rocks. While there have been advocates for the development of tectonic cleavages before host rock lithification these are currently viewed as essentially local aberrations without regional significance. In this study we combine new field observations with strain analysis, element mapping and modelling to characterise Acadian (>50%) crustal shortening in a Devonian clastic sedimentary sequence from the Dingle Peninsula of south west Ireland. Fabrics in these rocks reflect significant levels of tectonic shortening are a product of grain translation, rigid body rotation and repacking of intra- and extra-formational clasts during deformation of an unconsolidated clastic sedimentary sequence. There is an absence of the expected domainal cleavage structure and intra-clast deformation expected with conventional cleavage formation. This study requires geologists to consider the possibility such a mechanism contributing to tectonic strain in a wide range of geological settings and to look again at field evidence that indicates early sediment mobility during deformation.

Mobility of arsenic in a Bangladesh aquifer: Inferences from geochemical profiles, leaching data, and mineralogical characterization

NASA Astrophysics Data System (ADS)

Swartz, Christopher H.; Blute, Nicole Keon; Badruzzman, Borhan; Ali, Ashraf; Brabander, Daniel; Jay, Jenny; Besancon, James; Islam, Shafiqul; Hemond, Harold F.; Harvey, Charles F.

2004-11-01

Aquifer geochemistry was characterized at a field site in the Munshiganj district of Bangladesh where the groundwater is severely contaminated by As. Vertical profiles of aqueous and solid phase parameters were measured in a sandy deep aquifer (depth >150 m) below a thick confining clay (119 to 150 m), a sandy upper aquifer (3.5 to 119 m) above this confining layer, and a surficial clay layer (<3.5 m). In the deep aquifer and near the top of the upper aquifer, aqueous As levels are low (<10 μg/L), but aqueous As approaches a maximum of 640 μg/L at a depth of 30 to 40 m and falls to 58 μg/L near the base (107 m) of the upper aquifer. In contrast, solid phase As concentrations are uniformly low, rarely exceeding 2 μg/g in the two sandy aquifers and never exceeding 10 μg/g in the clay layers. Solid phase As is also similarly distributed among a variety of reservoirs in the deep and upper aquifer, including adsorbed As, As coprecipitated in solids leachable by mild acids and reductants, and As incorporated in silicates and other more recalcitrant phases. One notable difference among depths is that sorbed As loads, considered with respect to solid phase Fe extractable with 1 N HCl, 0.2 M oxalic acid, and a 0.5 M Ti(III)-citrate-EDTA solution, appear to be at capacity at depths where aqueous As is highest; this suggests that sorption limitations may, in part, explain the aqueous As depth profile at this site. Competition for sorption sites by silicate, phosphate, and carbonate oxyanions appear to sustain elevated aqueous As levels in the upper aquifer. Furthermore, geochemical profiles are consistent with the hypothesis that past or ongoing reductive dissolution of Fe(III) oxyhydroxides acts synergistically with competitive sorption to maintain elevated dissolved As levels in the upper aquifer. Microprobe data indicate substantial spatial comapping between As and Fe in both the upper and deep aquifer sediments, and microscopic observations reveal ubiquitous Fe coatings on most solid phases, including quartz, feldspars, and aluminosilicates. Extraction results and XRD analysis of density/magnetic separates suggest that these coatings may comprise predominantly Fe(II) and mixed valence Fe solids, although the presence of Fe(III) oxyhydroxides can not be ruled out. These data suggest As release may continue to be linked to dissolution processes targeting Fe, or Fe-rich, phases in these aquifers.

Hermetically sealed electrical feedthrough for high temperature secondary cells

DOEpatents

Knoedler, R.; Nelson, P.A.; Shimotake, H.; Battles, J.E.

1983-07-26

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

Hermetically sealed electrical feedthrough for high temperature secondary cells

DOEpatents

Knoedler, Reinhard; Nelson, Paul A.; Shimotake, Hiroshi; Battles, James E.

1985-01-01

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

Effect of the 1997 El Niño on the distribution of upper tropospheric cirrus

NASA Astrophysics Data System (ADS)

Massie, Steven; Lowe, Paul; Tie, Xuexi; Hervig, Mark; Thomas, Gary; Russell, James

2000-09-01

Geographical distributions of Halogen Occultation Experiment (HALOE) aerosol extinction data for 1993-1998 are analyzed in the troposphere and stratosphere at pressures between 121 and 46 hPa. The El Niño conditions of 1997 increased upper tropospheric cirrus over the mid-Pacific and decreased cirrus over Indonesia. Longitudinal centroids of cirrus in the Pacific and over Indonesia shifted eastward by 25° in the troposphere in 1997. Longitudinal centroids of aerosol in the lower stratosphere do not exhibit longitudinal shifts in 1997, indicating that the effects of El Niño upon equatorial particle distributions are confined to the troposphere. The correlation of the longitudinal centroids of outgoing longwave radiation and HALOE extinction confirms the spatial relationship between deep convective clouds and upper tropospheric cirrus. The number of cirrus events observed each year in 1993-1998 in the upper troposphere are quite similar for the region from the Indian Ocean to the mid-Pacific (30°S to 30°N, 50° to 240°E).

High-resolution seismic reflection to delineate shallow gas in Eastern Kansas

USGS Publications Warehouse

Miller, R.D.; Watney, W.L.; Begay, D.K.; Xia, J.

2000-01-01

Unique amplitude characteristics of shallow gas sands within Pennsylvanian clastic-carbonate dominated sequences are discernible on high-resolution seismic reflection data in eastern Kansas. Upward grading sequences of sand into shale represent a potential gas reservoir with a low-impedence acoustic contrast at the base of the encasing layer. The gas sand and encasing shale, which define the gas reservoir studied here, are part of an erosional incised valley where about 30 m of carbonates and shale have been replaced by sandstone and shale confined to the incised valley. These consolidated geologic settings would normally possess high impedence gas sand reservoirs as defined by abrupt contacts between the gas sand and encasing shale. Based orr core and borehole logs, the gas sand studied here grades from sand into shale in a fashion analogous to that observed in classic low-impedance environments. Amplitude and phase characteristics of high-resolution seismic data across this approximately 400-m wide gas sand are indicative of a low-impedance reservoir. Shot gathers possess classic amplitude with offsett-dependent characteristics which are manifeted on the stacked section as "bright spots." Dominant Frequencies of around 120 Hz allow detection of several reflectors within the 30+ meters of sand/shale that make up this localized gas-rich incised valley fill. The gradational nature of the trapping mechanism observed in this gas reservoir would make detection with conventional seismic reflection methods unlikely.

Factors Affecting Water Quality in Domestic Wells in the Upper Floridan Aquifer, Southeastern United States, 1998-2005

USGS Publications Warehouse

Berndt, Marian P.; Crandall, Christy A.; Deacon, Michael; Embry, Teresa L.; Howard, Rhonda S.

2009-01-01

The Floridan aquifer system is a highly productive carbonate aquifer that provides drinking water to about 10 million people in Florida, Georgia, and South Carolina. Approximately 1.6 million people rely on domestic wells (privately owned household wells) for drinking water. Withdrawals of water from the Floridan aquifer system have increased by more than 500 percent from 630 million gallons per day (2.38 cubic meters per day) in 1950 to 4,020 million gallons per day (15.2 cubic meters per day) in 2000, largely due to increases in population, tourism, and agriculture production. Water samples were collected from 148 domestic wells in the Upper Floridan aquifer in Florida, Georgia, South Carolina, and Alabama during 1998-2005 as part of the U.S. Geological Survey (USGS) National Water-Quality Assessment Program. The wells were located in different hydrogeologic settings based on confinement of the Upper Floridan aquifer. Five networks of wells were sampled con-sisting of 28 to 30 wells each: two networks were in unconfined areas, two networks were in semiconfined areas, and one network was in the confined area. Physical properties and concentrations of major ions, trace elements, nutrients, radon, and organic compounds (volatile organic compounds and pesticides) were measured in water samples. Concentrations were compared to water-quality benchmarks for human health, either U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Levels (MCLs) for public water supplies or USGS Health-Based Screening Levels (HBSLs). The MCL for fluoride of 4 milligrams per liter (mg/L) was exceeded for two samples (about 1 percent of samples). A proposed MCL for radon of 300 picocuries per liter was exceeded in about 40 percent of samples. Nitrate concentrations in the Upper Floridan aquifer ranged from less than the laboratory reporting level of 0.06 to 8 mg/L, with a median nitrate concentration less than 0.06 mg/L (as nitrogen). Nitrate concentrations did not exceed the MCL of 10 mg/L. Statistical comparisons indicated that median nitrate concentrations were significantly different by degree of confinement where the highest median nitrate concentration was 1.46 mg/L for 58 samples from unconfined areas, and by network, where the highest median nitrate concentration was 2.43 mg/L in 28 samples from unconfined areas in southwestern Georgia. Nitrate concentrations in unconfined areas were positively correlated to: (1) the percentage of agricultural land use around the well, (2) the amount of nitrogen fertilizer applied, and (3) the dissolved oxygen concentrations in groundwater. Volatile organic compounds (VOCs) were detected in about 63 percent of all samples. Chloroform, carbon disulfide, and 1,2-dichloropropane were the most frequently detected VOCs. Chloroform, a byproduct of water chlorination, was most frequently detected in unconfined urban areas. Carbon disulfide, a solvent, was most frequently detected in confined areas in southeastern Georgia. Pesticides were detected in about 21 percent of all samples, but were detected in about 69 percent of the 28 samples from unconfined areas in southwestern Georgia. The herbicides atrazine, deethylatrazine, and metolachlor were the most frequently detected pesticides.

Compositional characteristics of some Apollo 14 clastic materials.

NASA Technical Reports Server (NTRS)

Lindstrom, M. M.; Duncan, A. R.; Fruchter, J. S.; Mckay, S. M.; Stoeser, J. W.; Goles, G. G.; Lindstrom, D. J.

1972-01-01

Eighty-two subsamples of Apollo 14 materials have been analyzed by instrumental neutron activation analysis techniques for as many as 25 elements. In many cases, it was necessary to develop new procedures to allow analyses of small specimens. Compositional relationships among Apollo 14 materials indicate that there are small but systematic differences between regolith from the valley terrain and that from Cone Crater ejecta. Fragments from 1-2 mm size fractions of regolith samples may be divided into compositional classes, and the 'soil breccias' among them are very similar to valley soils. Multicomponent linear mixing models have been used as interpretive tools in dealing with data on regolith fractions and subsamples from breccia 14321. These mixing models show systematic compositional variations with inferred age for Apollo 14 clastic materials.

Nature of the H chondrite parent body regolith - Evidence from the Dimmitt breccia

NASA Technical Reports Server (NTRS)

Rubin, A. E.; Scott, E. R. D.; Taylor, G. J.; Keil, K.; Allen, J. S. B.; Mayeda, T. K.; Clayton, R. N.; Bogard, D. D.

1983-01-01

Meteorite regolith breccias are clastic rocks which formed by lithification of fragmental regolith material that once resided at the surface of a meteorite parent body. A study is reported of the matrix and 21 clasts of various sizes (0.2-24 mm) in the Dimmitt H chondrite regolith breccia using petrographic and electron microprobe techniques. In addition, oxygen isotope studies of three clasts and instrumental neutron activation analysis (INAA) and Ar-39/Ar-40 age dating of one clast are reported. The Dimmitt meteorite was found about 1942 near Dimmitt, Texas. Attention is given to analytical procedures, the clastic matrix, equilibrated clasts, poikilitic melt-rock clast, clasts of different chondrite groups, graphite-magnetite aggregates, the origin of exotic clasts, and the complexity of parent body surfaces processes.

Rates, timing, and cyclicity of Holocene eolian activity in north-central United States: Evidence from varved lake sediments

USGS Publications Warehouse

Dean, W.E.

1997-01-01

Most of the sediment components that accumulated in Elk Lake, northwestern Minnesota, during the Holocene are autochthonous or biogenic, delivered to the sediment-water interface on a seasonal schedule, preserved in distinct annual laminae (varves). The main allochthonous component is detrital clastic material, as measured by bulk-sediment concentrations of aluminum, sodium, potassium, titanium, and quartz, that enters the lake mostly as eolian dust. The eolian clastic influx to Elk Lake was considerably greater during the mid-Holocene (8-4 ka) than it has been for the past 4000 yr, when periods of increased eolian activity correspond to the time of the Little Ice Age and the dust bowl. Geochemical records of eolian activity exhibit distinct cyclicities with dominant periodicities of 400 and 84 yr.

Funalichnus bhubani isp. nov. from Bhuban Formation, Surma Group (Lower -Middle Miocene) of Aizawl, Mizoram, India

PubMed Central

Tiwari, Raghavendra Prasad; Rajkonwar, Chinmoy; Patel, Satish Jaychandbhai

2013-01-01

A new ichnospecies of the ichnogenus Funalichnus Pokorný is described from the Middle Bhuban Unit, Bhuban Formation, Surma Group (Lower - Middle Miocene) of Aizawl, Mizoram, India. Funalichnus bhubani isp. Nov. Is a large burrow displaying cylindrical segments that are oriented nearly perpendicular to the bedding plane. The new ichnospecies can be identified on the basis of general form, size, unlined passive filling and twisted rod-like structure. The association of Funalichnus bhubani isp. Nov. With Arenicolites, Diplocraterion, Ophiomorpha Psilonichnus Skolithos and Thalassinoides points to its bathymetric restriction. The deep extension of the burrow in clastic sediments provides a favourable condition for preservation in the shoreface environment and occurrence in fine- to medium-grained clastic sediments may be a preservational preference. PMID:24204992

Fresh and Salt Water Distribution in Passive Margin Sediments: Insights from Iodp Expedition 313 ON the New Jersey Margin

NASA Astrophysics Data System (ADS)

Lofi, J.; Inwood, J.; Proust, J.; Monteverde, D.; Loggia, D.; Basile, C.; Hayashi, T.; Stadler, S.; Fehr, A.; Pezard, P.

2012-12-01

For the first time in the history of international scientific drillings, the Integrated Ocean Drilling Program (IODP) mission-specific platform (MSP) Expedition 313 drilled three 631-755 m-deep boreholes on the middle shelf of a clastic passive margin. This expedition gathered a full set of geophysical data tied to drillcores with 80% of recovery. It offers a unique opportunity to access the internal structure of a siliciclastic system, at scales ranging from the matrix to the margin, and to correlate the geological skeleton with the spatial distribution and salinity of saturating fluids. In addition to the discovery of very low salinity pore water (<3g/l) at depths exceeding 400 m below the middle shelf, this expedition provides evidence for a multi-layered reservoir, with fresh/brackish water intervals alternating vertically with salty intervals. Our observations suggest that the processes controlling salinity distribution are strongly influenced by lithology, porosity and permeability. Saltier pore waters are recovered in less porous, more permeable, intervals whereas fresher pore waters are recovered in more porous, less permeable, intervals. Pore water concentrations are inversely correlated to the Thorium content, with high salinities in low Th intervals (i.e. sandy formations). The transition from fresher to saltier intervals is often marked by cemented horizons acting as permeability barrier. In the lower part of some holes, the salinity varies independently of lithology, suggesting different mechanisms and/or sources of salinity. We have developed a 2D model of permeability distribution along a dip transect of the margin, extrapolated from combined clinoform geometries observed on seismic data and sedimentary facies described on cores. This model clearly illustrates the importance of taking into account the spatial heterogeneity of geological system at several scales. Lithology reflects permeability at a small scale whereas seismic facies and system tracts can be used to infer the reservoir geometry at a larger scale. Four main reservoirs (R1 to R4) that are relatively disconnected have been identified. These are essentially developed in coarse-grained deposits observed either in some clinoform topsets (R4), in upper foresets (R2, R3), or in both of them (R1). R2 to R4 contain salty water while the most proximal reservoir R1, located close to the coastline, is saturated with fresh water, and may form the seaward extension of onshore aquifers. Each of these four reservoirs is separated by confining units of varied thicknesses and of relatively broad spatial extension. At the Expedition 313 drilling sites, the fresh waters stored in confining units have a post-deposition age and may have a fossil origin (Pleistocene low-stands?), whereas saltier water recovered in distal reservoirs (R2 to R4) penetrated at a later stage. Further work must be done to clarify the emplacement mechanisms. Future studies should focus on the inclusion of our 2D permeability model in a groundwater model, in order to examine the specific flow processes that are active in this environment. This research used samples and data provided by the Integrated Ocean Drilling Program (IODP) and the International Continental Scientific Drilling Program (ICDP).

The integrated impacts of natural processes and human activities on the origin and processes of groundwater salinization in the coastal aquifers of Beihai, Southern China

NASA Astrophysics Data System (ADS)

Li, Q.; Zhan, Y., , Dr; Chen, W. Ms; Yu, S., , Dr

2017-12-01

Salinization in coastal aquifers usually is the results of contamination related to both seawater intrusion and water-rock interaction. The chemical and isotopic methods were combined to identify the origin and processes of groundwater salinization in Daguansha area of Beihai. The concentrations of the major ions that dominate in sea water (Cl-, Na+, Ca2+, Mg2+ and SO2- 4), as well as the isotopic ratios (2H, 18O, 87Sr/86Sr and 13C) suggest that the salinization occurring in the aquifer water of the coastal plain is related to seawater and the prevailing hydrochemical processes are evaporation, mixing, dissolution and ion exchange. For the unconfined aquifer, groundwater salinization occurred in parts of the area, which is significantly influenced by the land-based sea farming. The integrated impacts of seawater intrusion from the Beibuwan Gulf and infiltration of seawater from the culture ponds is identified in the confined aquifer I at site BBW2. In consequence, the leakage from this polluted aquifer causes the salinization of groundwater in the confined aquifer II. At site BBW3, the confined aquifer I and lower confined aquifer II are remarkably contaminated by seawater intrusion. The weak connectivity with upper aquifers and seaward movement of freshwater prevents saltwater from encroaching the confined aquifer III. Above all, understanding of the origin and processes of groundwater salinization will provide essential information for sustainable planning and management of groundwater resources in this region.

Investigation of the Rock Fragmentation Process by a Single TBM Cutter Using a Voronoi Element-Based Numerical Manifold Method

NASA Astrophysics Data System (ADS)

Liu, Quansheng; Jiang, Yalong; Wu, Zhijun; Xu, Xiangyu; Liu, Qi

2018-04-01

In this study, a two-dimensional Voronoi element-based numerical manifold method (VE-NMM) is developed to analyze the granite fragmentation process by a single tunnel boring machine (TBM) cutter under different confining stresses. A Voronoi tessellation technique is adopted to generate the polygonal grain assemblage to approximate the microstructure of granite sample from the Gubei colliery of Huainan mining area in China. A modified interface contact model with cohesion and tensile strength is embedded into the numerical manifold method (NMM) to interpret the interactions between the rock grains. Numerical uniaxial compression and Brazilian splitting tests are first conducted to calibrate and validate the VE-NMM models based on the laboratory experiment results using a trial-and-error method. On this basis, numerical simulations of rock fragmentation by a single TBM cutter are conducted. The simulated crack initiation and propagation process as well as the indentation load-penetration depth behaviors in the numerical models accurately predict the laboratory indentation test results. The influence of confining stress on rock fragmentation is also investigated. Simulation results show that radial tensile cracks are more likely to be generated under a low confining stress, eventually coalescing into a major fracture along the loading axis. However, with the increase in confining stress, more side cracks initiate and coalesce, resulting in the formation of rock chips at the upper surface of the model. In addition, the peak indentation load also increases with the increasing confining stress, indicating that a higher thrust force is usually needed during the TBM boring process in deep tunnels.

Provenance and U-Pb geochronology of the Upper Cretaceous El Chanate Group, northwest Sonora, Mexico, and its tectonic significance

USGS Publications Warehouse

Jacques-Ayala, C.; Barth, A.P.; Wooden, J.L.; Jacobson, C.E.

2009-01-01

The Upper Cretaceous El Chanate Group, northwest Sonora, Mexico, is a 2.8km thick clastic sedimentary sequence deposited in a continental basin closely related to volcanic activity. It consists of three formations: the Pozo Duro (oldest), the Anita, and the Escalante (youngest). Petrographic study, conglomerate pebble counts, and U-Pb geochronology of detrital zircons were performed to determine the source and age of this sequence, and to interpret its tectonic setting. In the sandstones of all three formations, the most abundant grains are those of volcanic composition (Q38F22L 40, Q35F19L46, and Q 31F22L47, respectively). The Pozo Duro Formation includes well-rounded quartz-arenite clast conglomerates, whereas conglomerates of the two upper units have clasts predominantly of andesitic and rhyolitic composition. The most likely source for these sediments was the Jurassic volcanic arc exposed in northern Sonora and southern Arizona. Zircons from five sandstone samples define two main age groups, Proterozoic and Mesozoic. The first ranges mostly from 1000 to 1800Ma, which suggests the influence of a cratonic source. This zircon suite is interpreted to be recycled and derived from the same source area as the quartz-rich sandstone clasts in the basal part of the section. Mesozoic zircons range from Triassic to Late Cretaceous, which confirms the proposed Late Cretaceous age for the sequence, and also corroborates Jurassic felsic source rocks. Another possible source was the Alisitos volcanic arc, exposed along the western margin of the Baja California Peninsula. Of regional significance is the great similarity between the El Chanate Group and the McCoy Mountains Formation of southeastern California and southwestern Arizona. Both are Cretaceous, were deposited in continental environments, and have similar zircon-age patterns. Also, both exhibit intense deformation and locally display penetrative foliation. These features strongly suggest that both units underwent similar tectonic histories.

Chapter 2. Assessment of undiscovered conventional oil and gas resources--Upper Jurassic-Lower Cretaceous Cotton Valley group, Jurassic Smackover interior salt basins total petroleum system, in the East Texas basin and Louisiana-Mississippi salt basins provinces.

USGS Publications Warehouse

Dyman, T.S.; Condon, S.M.

2006-01-01

The Jurassic Smackover Interior Salt Basins Total Petroleum System is defined for this assessment to include (1) Upper Jurassic Smackover Formation carbonates and calcareous shales and (2) Upper Jurassic and Lower Cretaceous Cotton Valley Group organic-rich shales. The Jurassic Smackover Interior Salt Basins Total Petroleum System includes four conventional Cotton Valley assessment units: Cotton Valley Blanket Sandstone Gas (AU 50490201), Cotton Valley Massive Sandstone Gas (AU 50490202), Cotton Valley Updip Oil and Gas (AU 50490203), and Cotton Valley Hypothetical Updip Oil (AU 50490204). Together, these four assessment units are estimated to contain a mean undiscovered conventional resource of 29.81 million barrels of oil, 605.03 billion cubic feet of gas, and 19.00 million barrels of natural gas liquids. The Cotton Valley Group represents the first major influx of clastic sediment into the ancestral Gulf of Mexico. Major depocenters were located in south-central Mississippi, along the Louisiana-Mississippi border, and in northeast Texas. Reservoir properties and production characteristics were used to identify two Cotton Valley Group sandstone trends across northern Louisiana and east Texas: a high-permeability blanket-sandstone trend and a downdip, low-permeability massive-sandstone trend. Pressure gradients throughout most of both trends are normal, which is characteristic of conventional rather than continuous basin-center gas accumulations. Indications that accumulations in this trend are conventional rather than continuous include (1) gas-water contacts in at least seven fields across the blanket-sandstone trend, (2) relatively high reservoir permeabilities, and (3) high gas-production rates without fracture stimulation. Permeability is sufficiently low in the massive-sandstone trend that gas-water transition zones are vertically extensive and gas-water contacts are poorly defined. The interpreted presence of gas-water contacts within the Cotton Valley massive-sandstone trend, however, suggests that accumulations in this trend are also conventional.

Identification of remagnetization processes in Paleozoic sedimentary rocks of the northeast Rhenish Massif in Germany by K-Ar dating and REE tracing of authigenic illite and Fe oxides

NASA Astrophysics Data System (ADS)

Zwing, A.; Clauer, N.; Liewig, N.; Bachtadse, V.

2009-06-01

This study combines mineralogical, chemical (rare earth elemental (REE)) and isotopic (K-Ar) data of clay minerals as well as chemical compositions (major and REE) of Fe oxide leachates from remagnetized Palaeozoic sedimentary rocks from NE Rhenish Massif in Germany, for which the causes of remagnetization are not yet clear. The dominant carrier of the syntectonic, pervasive Carboniferous magnetization is magnetite. The Middle Devonian clastic rocks record an illitization event at 348 ± 7 Ma probably connected to a major magmatic event in the Mid-German Crystalline Rise, whereas a second illitization episode at 324 ± 3 Ma is coeval to the northward migrating deformation through the Rhenish Massif, being only detected in Upper Devonian and Lower Carboniferous rocks. The age of that younger illitization is not significantly different from that of the remagnetization, which, however, is not restricted to the upper part of the orogenic belt, but affects also the Middle Devonian strata. The REE patterns of the Fe-enriched leachates support two mineralization episodes with varied oxidation-reduction conditions outlined by varied Eu and Ce anomalies. This is not compatible with a unique, pervasive migration of orogenic fluids on a regional scale to explain the remagnetization in the studied region. While clay diagenesis and remagnetization are time-equivalent in Upper Devonian and Lower Carboniferous rocks, they are not so in Middle Devonian rocks. Transformation of smectite into illite cannot, therefore, account for the growth of associated authigenic magnetite, which must have been triggered by a different process. Since remagnetization and deformation ages are similar, the mechanism could relate to local physical conditions such as pressure solution and changing pore fluid pressure due to tectonic stress as well as to chemical conditions such as changing composition of the pore fluids.

Large-scale mud diapirism as a record of late-stage Laramide tectonism within the Eocene Green River Formation, Wyoming

NASA Astrophysics Data System (ADS)

Hudson, Samuel M.; Klimek, Jason N.

2017-08-01

The Gruene and Verde mud diapirs, which range in size from 70 to 95 m in diameter, are exposed within the Wilkins Peak Member of the Eocene Green River Formation near Flaming Gorge Reservoir, southwest Wyoming. These diapirs are sourced from the lower unit of the Wilkins Peak Member (lower, middle, and upper units can be defined based on dominant lithology), and were emplaced into the upper unit of the Wilkins Peak Member, cross-cutting hundreds of meters of strata. The structures contain brecciated dolomicritic and lime mudstones with minor amounts of siliciclastic clays. Pervasive quartz veining is present throughout both diapirs. Though heavily disturbed, original bedding can be seen in both localities, either dipping radially outward towards the margins of the diapir as is dominant at the Gruene diapir or tilted but near horizontal as is the dominant expression at the smaller Verde diapir. The Gruene diapir can be seen in contact with several fluvial sandstone bodies within the upper Wilkins Peak strata in outcrop, and these fluvial sandstones transition from regional, near-horizontal dips to steeply dipping beds and bedsets within 50 m of the diapir. These sands show no signs of brittle deformation, and dip ranges from 20 to 50° radially away from the center of the diapir to the north, west, and east where sands are observed. These are interpreted here to have been deformed pre-lithification, at or near the surface, by the rising mud diapir, offering an important control on the timing of diapirism near the end of the early Eocene. Deformation structures such as clastic dikes, brecciation, and convoluted bedding have been documented by others at or near this stratigraphic interval in Utah, Wyoming, and Colorado, and these smaller structures have been interpreted as seismites. We suggest that these mud diapirs are a larger-scale expression of this same seismic activity.

Well-Production Data and Gas-Reservoir Heterogeneity -- Reserve Growth Applications

USGS Publications Warehouse

Dyman, Thaddeus S.; Schmoker, James W.

2003-01-01

Oil and gas well production parameters, including peakmonthly production (PMP), peak-consecutive-twelve month production (PYP), and cumulative production (CP), are tested as tools to quantify and understand the heterogeneity of reservoirs in fields where current monthly production is 10 percent or less of PMP. Variation coefficients, defined as VC= (F5-F95)/F50, where F5, F95, and F50 are the 5th, 95th, and 50th (median) fractiles of a probability distribution, are calculated for peak and cumulative production and examined with respect to internal consistency, type of production parameter, conventional versus unconventional accumulations, and reservoir depth. Well-production data for this study were compiled for 69 oil and gas fields in the Lower Pennsylvanian Morrow Formation of the Anadarko Basin, Oklahoma. Of these, 47 fields represent production from marine clastic facies. The Morrow data were supplemented by data from the Upper Cambrian and Lower Ordovician Arbuckle Group, Middle Ordovician Simpson Group, Middle Pennsylvanian Atoka Formation, and Silurian and Lower Devonian Hunton Group of the Anadarko Basin, one large gas field in Upper Cretaceous reservoirs of north-central Montana (Bowdoin field), and three areas of the Upper Devonian and Lower Mississippian Bakken Formation continuous-type (unconventional) oil accumulation in the Williston Basin, North Dakota and Montana. Production parameters (PMP, PYP, and CP) measure the net result of complex geologic, engineering, and economic processes. Our fundamental hypothesis is that well-production data provide information about subsurface heterogeneity in older fields that would be impossible to obtain using geologic techniques with smaller measurement scales such as petrographic, core, and well-log analysis. Results such as these indicate that quantitative measures of production rates and production volumes of wells, expressed as dimensionless variation coefficients, are potentially valuable tools for documenting reservoir heterogeneity in older fields for field redevelopment and risk analysis.

Upper crustal structure of the North Anatolian Fault Zone from ambient seismic noise Rayleigh and Love wave tomography

NASA Astrophysics Data System (ADS)

Taylor, George; Rost, Sebastian; Houseman, Gregory; Hillers, Gregor

2017-04-01

By utilising short period surface waves present in the noise field, we can construct images of shallow structure in the Earth's upper crust: a region that is usually poorly resolved in earthquake tomography. Here, we use data from a dense seismic array (Dense Array for Northern Anatolia - DANA) deployed across the North Anatolian Fault Zone (NAFZ) in the region of the 1999 magnitude 7.6 Izmit earthquake in western Turkey. The NAFZ is a major strike-slip system that extends ˜1200 km across northern Turkey and continues to pose a high level of seismic hazard, in particular to the mega-city of Istanbul. We obtain maps of group velocity variation using surface wave tomography applied to short period (1- 6 s) Rayleigh and Love waves to construct high-resolution images of the upper 5 km of a 70 km x 35 km region centred on the eastern end of the fault segment that ruptured in the 1999 Izmit earthquake. The average Rayleigh wave group velocities in the region vary between 1.8 km/s at 1.5 s period, to 2.2 km/s at 6 s period. The NAFZ bifurcates into northern and southern strands in this region; both are active but only the northern strand moved in the 1999 event. The signatures of both the northern and southern branches of the NAFZ are clearly associated with strong gradients in surface wave group velocity. To the north of the NAFZ, we observe low Rayleigh wave group velocities ( 1.2 km/s) associated with the unconsolidated sediments of the Adapazari basin, and blocks of weathered terrigenous clastic sediments. To the south of the northern branch of the NAFZ, we detect high velocities ( 2.5 km/s) associated with a shallow crystalline basement, in particular a block of metamorphosed schists and marbles that bound the northern branch of the NAFZ.

Geohydrology and water quality in northern Portage County, Ohio, in relation to deep-well brine injection

USGS Publications Warehouse

Eberts, S.M.

1991-01-01

Geohydrology and water quality of the principal freshwater aquifers near oilfield and gasfield brine-injection wells in northern Portage County, Ohio, were evaluated. Since 1975, 13 wells in this part of the Country have been used to dispose of more than 4.5 million barrels of brine by injection into Silurian carbonate and sandstone rocks that generally are greater than 3,500 feet below land surface. More than 3,000 feet of interbedded shales, sandstones, carbonates, and evaporites separate the freshwater aquifers from these brine-injection zones. The shallowest brine-injection zone is greater than 2,200 feet below sea level. Native fluids in the injection zones have dissolved-solids concentrations greater than 125,000 milligrams per liter and are hydraulically isolated from the freshwater aquifers. No known faults or fracture systems are present in northern Portage County, although abandoned oil and gas wells could exist and serve as conduits for migration of injected brine. Pennsylvanian clastic units are freshwater bearing in northern Portage County, and two bedrock aquifers generally are recognized. The shallower bedrock aquifer (Connoquenessing Sandstone Member of the Pottsville Formation) principally consists of sandstone; this aquifer is separated from a deeper sandstone and conglomerate aquifer in the lower part of the Sharon Member (Pottsville Formation) by shale in the upper part of the Sharon Member that acts as a confining unit. The upper sandstone aquifer is the surficial aquifer where overlying glacial deposits are unsaturated in the uplands; glacial deposits comprise the surficial aquifer in buried valleys where the sandstone is absent. These two surficial aquifers are hydraulically connected and act as a single unit. The lower sandstone and conglomerate aquifer is the most areally extensive aquifer within the project area. From November 1987 through August 1988, ground-water levels remained at least 60 feet higher in the upper sandstone aquifer than in the lower sandstone and conglomerate aquifer at a topographically high recharge area. Water levels in the surficial aquifers and the lower sandstone and conglomerate aquifer were nearly the same along the Cuyahoga River. Ground water in the upper sandstone aquifer flows radially from topographically high recharge areas into the glacial deposits in the buried valleys. Much of the ground water in these surficial aquifers discharges into the Cuyahoga River. Most ground water in the lower sandstone and conglomerate aquifer flows toward discharge areas near the Cuyahoga River and Eagle Creek. In June 1988, the Cuyahoga River gained 15.8 cubic feet per second of water from the aquifers between the northern edge of Portage County and State Route 303. Ground water may have discharged into the upstream end of Lake Rockwell but did not discharge into the downstream end of the Lake during most of the period from October 1987 through September 1988. Measurements of the specific conductance of ground water sampled from areas near the 13 brine-injection wells and along the Cuyahoga River indicate no widespread ground-water contamination related to brine injection. Chemical analysis of water from 25 wells indicates that most ground waters are a calcium bicarbonate type. Water analyses show that four wells sampled contain water with chloride concentrations greater than 250 milligrams per liter. Sodium concentrations in water from these four wells ranged from 67 to 190 milligrams per liter. A mixing diagram constructed from bromide and chloride data was used to distinguish between the sources of elevated chloride concentrations in these four wells. Waters from two of the wells have been mixed with oilfield and gasfield brine, and waters from the other two wells have been mixed with a salt-solution brine such as that derived from diluted highway-deicing salts.

Parametric decay instability near the upper hybrid resonance in magnetically confined fusion plasmas

NASA Astrophysics Data System (ADS)

Hansen, S. K.; Nielsen, S. K.; Salewski, M.; Stejner, M.; Stober, J.; the ASDEX Upgrade Team

2017-10-01

In this paper we investigate parametric decay of an electromagnetic pump wave into two electrostatic daughter waves, particularly an X-mode pump wave decaying into a warm upper hybrid wave (a limit of an electron Bernstein wave) and a warm lower hybrid wave. We describe the general theory of the above parametric decay instability (PDI), unifying earlier treatments, and show that it may occur in underdense and weakly overdense plasmas. The PDI theory is used to explain anomalous sidebands observed in collective Thomson scattering (CTS) spectra at the ASDEX Upgrade tokamak. The theory may also account for similar observations during CTS experiments in stellarators, as well as in some 1st harmonic electron cyclotron resonance and O-X-B heating experiments.

Practice of Field learning and its effect by using Hiikawa river distributed over Shimane prefecture, southwest Japan

NASA Astrophysics Data System (ADS)

Tomoyuki, U.; Matsumoto, I.

2013-12-01

The importance of field learning about geological feature has been increasing from a elementary to a undergraduate (university) student. Especially the field learning for elementary and junior high school student is important in it. However, the implementation rate of the field learning in an elementary and a junior high school is a low very much. The trend for a school with such a situation nearer to a large city to be stronger is recognized. They learn the erosion, transportation, and sedimentation by river water as science unite of grade 5 "Function of running water" of elementary school in Japan. As for Hii river, the granitoids is widely distributed over most of the basin from the upper stream to the down stream. Therefore, the most is the granitoids origin and we can look upon the clastic grains observed to the river floor and bank as a series of rocks and minerals from the upper stream to the lower stream. That is, since a student can make observation learning of the function of a river through grain size change of a granitoids and the mineral which constitutes it, Hii river is very good teaching material in this unit. Moreover, in this study, we carried out the questionnaire of the free description format including the general impression against a this field learning. The result of these questionnaires showed that student not only having studying the function of running water 'weathering', 'transportation' and 'sedimentation' with actual feelings, but also the actions of the river having spent tremendous time and having studied dominating the Space.

Trace fossils, storm beds, and depositional sequences in a clastic shelf setting, Upper Cretaceous of Utah

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

Frey, R.W.

In Coal Creek Canyon, Utah the Spring Canyon Member of the Blackhawk Formation is divisible into four regressive hemicycles of deposition each representing the downdip part of a nearshore-to-offshore sequence punctuated locally by hummocky cross-stratification. Bedding units span middle shoreface to lower offshore shelf lithofacies, the latter corresponding to a transgressive intertongue of the Mancos Shale. Trace fossil assemblage include 21 ichnospecies distributed among 17 ichnogenera: Ancorichnus, Aulichnites, Chondrites, Cylindrichnus, Ophiomorpha, Palaeophycus, Phoebichnus, Planolites, Rosselia, Schaubcylindrichnus, Scolicia, Skolithos, Taenidium, Teichichnus, Terebellina, Thalassinoides, and Uchirites. Distal deposits are typified by bioturbate textures; Cylindrichnus concentricus, Palaeophycus heberti, and Rosselia socialis otherwise aremore » prevalent throughout the lithofacies suite. Ophiomorpha irregulaire and Schaubcylindrichnus are most common in middle shoreface beds and Chondrites sp. in upper offshore beds; O. nodosa and O. annulata also are common in this part of the sequence. Planolites-type feeding burrows must have been predominant in many depositional settings but now remain inconspicuous and poorly preserved. Despite gradients in environmental distributions of trace fossils, all resident ichnofaunas are referable to the archetypical Cruziana ichnocoenose. Ichnofaunas in hummocky beds mainly represent either an archetypical Skolithos ichnocoenose or mixed Skolithos-Cruziana ichnocoenose. These post-storm ichnocoenoses correspond primarily to a sere of opportunistic pioneers and secondarily to ensuing seres of resilient resident populations. Differences in ichnofacies also are related to differences in post-storm rates of deposition: the slower the rate of sediment accumulation, the greater the degree of overprinting by burrows from subsequent seres or equilibrium communities.« less

Stratigraphy and sedimentation of Mississippian Ste. Genevieve-Cedar Bluff interval, Southwestern Indiana

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

Breedon, D.; Droste, J.B.; Murray, H.H.

1983-09-01

The Ste. Genevieve Limestone and Cedar Bluff Group of Mississippian age, both important sources of hydrocarbons in the Illinois basin, were traced from a subsurface stratigraphic section in White County, Illinois (described by Swan in 1963, across Gibson and Daviess Counties, Indiana, using electric logs and sample descriptions from 84 wells. The Ste. Genevieve Limestone is subdivided into four members and the Cedar Bluff Group into three formations. Six cross sections and nine isopach maps based on 300 wells show that these units comprise a succession of alternating fine- and coarse-grained carbonate rocks with only minor interruptions of sandstone andmore » shale. Two complete coarsening-upward cycles are apparent, and a third cycle is incomplete. Each cycle consists of a lower sequence of lime mudstones and wackestones, and an upper sequence of oolitic and skeletal grainstones. These cycles are the record of successive shoaling-upward cycles of sedimentation on a shallow marine platform. The lower mudstone-wackestone sequence represents deposition in a shallow subtidal environment, and the upper oolitic-skeletal grainstone unit represents development of oolite shoals and tidal channels in very shallow waters. Terrigenous clastic sediments brought into the basin by the Michigan river periodically encroached into the marine environment. Dolomitization of the fine-grained carbonate sediments is largely restricted to areas which are overlain by oolitic grainstones. In eastern Daviess County, indentification of the individual stratigraphic units in this interval is somewhat tenuous, but tracing the units from eastern Illinois into Indiana made correlation and identification of the individual stratigraphic units possible by using electric logs and sample descriptions.« less

Foraminiferal biostratigraphy, paleoenvironmental history, and rates of sedimentation within subsurface Miocene of southern Alabama and adjoining state and Federal Waters Areas

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

Smith, C.C.

1989-03-01

Miocene sedimentary rocks of the study area consist of a predominantly regressive sequence of clay and quartzose sand deposited on a carbonate platform which dips toward the southwest at 50-100 ft/mi. This clastic wedge ranges in thickness from 1000 ft in central Mobile and Baldwin Counties to a maximum of about 5800 ft in the northeastern portion of the Main Pass area. Analysis of planktonic and benthic foraminifera has resulted in a refined biostratigraphic zonation of these rocks, which indicates that basal Miocene transgressive shale assignable to the Amphistegina B interval zone immediately overlies the upper Oligocene regional carbonate platform.more » Thus, both lower and lower middle Miocene sedimentary rocks are absent throughout the area of investigation. Biostratigraphic analysis of the middle and upper Miocene rocks has resulted in a series of cross sections illustrating the dramatic thickening southwestward into the federal offshore continental shelf and showing the relationships of producing intervals in the Cibicides carstensi and Discorbis ''12'' interval zones. Paleoenvironmental interpretations are illustrated on a series of maps constructed for selected regional biostratigraphic zones. These maps have outlined previously unrecognized late middle and early late Miocene deltaic sedimentation in the southeastern Mobile County and Chandeleur-Viosca Knoll (north) areas. Study of sedimentation rates, which range from less than 25 up to 1370 ft/m.y., further aids in understanding the deltaic and coastal shelf sedimentation of the Miocene within Alabama and adjoining state and federal waters areas.« less

Petroleum geology of Amu-Dar'ya province of Soviet Central Asia

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

Clarke J.W.

1986-05-01

The Amu-Dar'ya oil and gas province extends over an area of 360,000 km/sup 2/ in central and eastern Turkmenia and western Uzbekistan in southern Soviet Central Asia. The province coincides with the eastern half of the Turan platform. A Mesozoic-Cenozoic sedimentary cover, 2-7 km thick, rests on a folded paleozoic basement. An Upper Jurassic salt unit divides the sedimentary section into subsalt and suprasalt parts. The structure of the sedimentary cover developed by vertical movements during the Mesozoic and Cenozoic, most of it during the late Tertiary in response to Alpine tectonism. Consequently, much of the trap formation and fillingmore » is late in geologic time and is apparently in progress at present. The province is gas prone; only in the Bukhara area on the east is there significant oil. Five plays are recognized. The Lower to Middle Jurassic play consists of alternating clays, sandstone, and siltstone. Thickness is 100-400 m. The Upper Jurassic play consists of Callovian-Oxfordian carbonate deposits, which are up to 500 m thick. The seal is Kimmeridgian-Tithonian salt. The carbonate deposits of this play are commonly a reef facies. The Lower Cretaceous play consists largely of alternating sandstone, clays, and siltstones. The seal is a clay unit of late Aptian and Albian age, which also separates this play from the overlying Albian-Cenomanian play. The Albian-Cenomanian play has sandstone and siltstone reservoirs, and the seal is a Turonian clay unit. The Paleogene play is prospective in the northeast part of the study area in the so-called Bukhara clastic beds.« less

Detrital zircon geochronology overlying the Naga Hills ophiolite

NASA Astrophysics Data System (ADS)

Roeder, T.; Aitchison, J.; Stojanovic, D.; Agarwal, A.; Ao, A.; Bhowmik, S.

2013-12-01

The Nagaland ophiolite in NE India represents the easternmost section of the ophiolitic belt running along the India-Asia suture. Outcrops near the border between Nagaland and Myanmar include not only a full suite of ophiolitic rocks but also high P/T blueschist rocks within a serpentinite-matrix mélange. Although Upper Jurassic radiolarians have been reported from the ophiolite itself (Baxter et al., 2011), few constraints have been placed on the timing of its emplacement onto India. Terrestrial sediments of the Phokphur Formation unconformably overlie the ophiolite. Similar to other sediments from along the ophiolite belt such as the Luiqu conglomerates in Tibet (Davis et al., 2002), they contain detritus derived from both the ophiolite and the continental margin onto which the ophiolite was emplaced. The clastic sediments of the Phokphur Formation potentially record not only the timing of ophiolite generation but also the ages of source terranes and can be used to place a minimum age constraint on the timing of ophiolite emplacement. As a contribution towards extending knowledge of the ophiolite belt and the India/Asia collision, we report preliminary results of an investigation into the sedimentology and detrital zircon geochronology of the Phokphur Formation in areas near Salumi and Zephu. Baxter, A.T., Aitchison, J.C., Zyabrev, S.V., Ali, J.R., 2011. Upper Jurassic radiolarians from the Naga Ophiolite, Nagaland, northeast India. Gondwana Research 20, 638-644. Davis, A.M., Aitchison, J.C., Badengzhu, Luo, H., Zyabrev, S., 2002. Paleogene island arc collision-related conglomerates, Yarlung-Tsangpo suture zone, Tibet. Sedimentary Geology 150, 247-273.

Chronostratigraphy and hydrocarbon habitat associated with the Jurassic carbonates of Abu Dhabi, United Arab Emirates

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

Alsharahan, A.S.; Whittle, G.L.

1995-08-01

Deposition of Jurassic epeiric shelf carbonates and evaporates were controlled by epeirogenic movement and sea level fluctuations which formed an excellent combination of source rocks, reservoirs and seats in Abu Dhabi. At the end of the Triassic, a relative drop in sea level, caused by eustatic sea level lowering in conjunction with minor tectonic uplift, resulted in non-deposition or erosion. In the Toarcian, deposition of carbonates and terrigenous, clastics produced the Marrat Formation. In the mid-Aalenian, a drop in sea level eroded much of the Marrat and some of the Triassic in offshore U.A.E. The deposition of the Hamlah Formationmore » followed, under neritic, well-oxygenated conditions. The Middle Jurassic was characterized by widespread, normal marine shelf carbonates which formed the cyclic Izhara and Araej formations (reservoirs). In the Upper Jurassic, the carbonate shelf became differentiated into a broad shelf with a kerogen-rich intrashelf basin, formed in response to a eustatic rise coupled with epeirogenic downwarping and marine flooding. The intrashelf basin fill of muddy carbonate sediments constitutes the Diyab Formation and its onshore equivalent, the Dukhan Formation (source rocks). In the late Upper Jurassic, the climate became more arid and cyclic deposition of carbonates and evaporates prevailed, forming alternating peritidal anhydrite, dolomite and limestone in the Arab Formation (reservoir). Arid conditions continued into the Tithonian, fostering the extensive anhydrite of the Hith Formation (seal) in a sabkha/lagoonal setting on the shallow peritidal platform, the final regressive supratidal stage of this major depositional cycle.« less

Geodatabase design and characteristics of geologic information for a geodatabase of selected wells penetrating the Austin Group in central Bexar County, Texas, 2010

USGS Publications Warehouse

Pedraza, Diana E.; Shah, Sachin D.

2010-01-01

The U.S. Geological Survey, in cooperation with the San Antonio Water System, developed a geodatabase of geologic and hydrogeologic information for selected wells penetrating the Austin Group in central Bexar County, Texas. The Austin Group functions as an upper confining unit to the Edwards aquifer and is the thickest and most permeable of the Edwards aquifer confining units. The geologic and hydrogeologic information pertains to a 377-square-mile study area that encompasses central Bexar County. Data were compiled primarily from drillers' and borehole geophysical logs from federal, State, and local agencies and published reports. Austin Group characteristics compiled for 523 unique wells are documented (if known), including year drilled, well depth, altitude of top and base of the Austin Group, and thickness of the Austin Group.

Ground-state energy of an exciton-(LO) phonon system in a parabolic quantum well

NASA Astrophysics Data System (ADS)

Gerlach, B.; Wüsthoff, J.; Smondyrev, M. A.

1999-12-01

This paper presents a variational study of the ground-state energy of an exciton-(LO) phonon system, which is spatially confined to a quantum well. The exciton-phonon interaction is of Fröhlich type, the confinement potentials are assumed to be parabolic functions of the coordinates. Making use of functional integral techniques, the phonon part of the problem can be eliminated exactly, leading us to an effective two-particle system, which has the same spectral properties as the original one. Subsequently, Jensen's inequality is applied to obtain an upper bound on the ground-state energy. The main intention of this paper is to analyze the influence of the quantum-well-induced localization of the exciton on its ground-state energy (or its binding energy, respectively). To do so, we neglect any mismatch of the masses or the dielectric constants, but admit an arbitrary strength of the confinement potentials. Our approach allows for a smooth interpolation of the ultimate limits of vanishing and infinite confinement, corresponding to the cases of a free three-dimensional and a free two-dimensional exciton-phonon system. The interpolation formula for the ground-state energy bound corresponds to similar formulas for the free polaron or the free exciton-phonon system. These bounds in turn are known to compare favorably with all previous ones, which we are aware of.

Potentiometric surface and water-level difference maps of selected confined aquifers in Southern Maryland and Maryland’s Eastern Shore, 1975-2013

USGS Publications Warehouse

Staley, Andrew W.; Andreasen, David C.; Curtin, Stephen E.

2014-01-01

The potentiometric surface maps show water levels ranging from 165 feet above sea level to 199 feet below sea level. Water levels have declined by as much as 113 feet in the Aquia aquifer since 1982, 81 feet in the Magothy aquifer since 1975, and 61 and 95 feet in the Upper Patapsco and Lower Patapsco aquifer systems, respectively, since 1990.

Amphibious Ready Group/Marine Expeditionary Unit Readiness Training Final Environmental Assessment

DTIC Science & Technology

2003-04-11

above and below by the Pensacola Clay confining bed. This clay layer restricts the downward migration of pollutants and restricts saline water from...separates the Upper and Lower Limestone units. Because it is saline , the Lower Limestone unit is not used as a water source (U.S. Air Force, 1995...and a freshwater species, Ruppia maritima (widgeon grass). Widgeon grass is most common in brackish waters but can tolerate higher salinities

Geologic, geotechnical, and geophysical properties of core from the Acme Fire-Pit-1 drill hole, Sheridan County, Wyoming

USGS Publications Warehouse

Collins, Donley S.

1983-01-01

A preliminary core study from the Acme Fire-Pit-1 drill hole, Sheridan County, Wyoming, revealed that the upper portion of the core had been baked by a fire confined to the underlying Monarch coal bed. The baked (clinkered) sediment above the Monarch coal bed was determined to have higher point-load strength values (greater than 2 MPa) than the sediment under the burned coal

Source of water to Lithia Springs in Hillsborough County, Florida

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

Hickey, J.J.; Coates, M.J.

1993-03-01

The source of water to Lithia Springs adjacent to the Alafia River in Hillsborough County, Florida has traditionally been hypothesized to be from the Upper Floridan aquifer. As a result, potential impacts from an adjacent public supply well field has been of interest since the well field began production in July, 1988. The discharge from Lithia Springs since March, 1984 has averaged about 3,600,000 cubic feet per day. Pumpage from the adjacent well field since July, 1988 has averaged about 2,500,000 cubic feet per day. A comparison between mean daily pumpage from the well field and mean daily discharge frommore » the springs showed no apparent association indicating that the Floridan aquifer may not be the source for the springs. Lithologic data suggested that the Upper Floridan aquifer was confined with no direct connection to the springs. This confining unit hypothesis was tested and accepted by pumping two wells close to the springs. The test consisted of pumping both wells for about 13 days at a combined rate that was about 40% of the average daily well field pumpage. No discernable test caused effects were observed on the springs or in an adjacent 115-foot deep well open to carbonate rock. Because of this, it was concluded that the Upper Floridan aquifer was not the source of water to Lithia Springs. Interpretation of available data suggested that the source of water to Lithia Springs was from the intermediate aquifer system located within solution riddled Early Miocene carbonate rocks of the lower Hawthorn Formation with maybe an important aquifer contribution from the Alafia River.« less

Prediction of soil organic carbon with different parent materials development using visible-near infrared spectroscopy.

PubMed

Liu, Jinbao; Han, Jichang; Zhang, Yang; Wang, Huanyuan; Kong, Hui; Shi, Lei

2018-06-05

The storage of soil organic carbon (SOC) should improve soil fertility. Conventional determination of SOC is expensive and tedious. Visible-near infrared reflectance spectroscopy is a practical and cost-effective approach that has been successfully used SOC concentration. Soil spectral inversion model could quickly and efficiently determine SOC content. This paper presents a study dealing with SOC estimation through the combination of soil spectroscopy and stepwise multiple linear regression (SMLR), partial least squares regression (PLSR), principal component regression (PCR). Spectral measurements for 106 soil samples were acquired using an ASD FieldSpec 4 standard-res spectroradiometer (350-2500 nm). Six types of transformations and three regression methods were applied to build for the quantification of different parent materials development soil. The results show that (1)the basaltic volcanic clastics development of SOC spectral response bands located in 500 nm, 800 nm; Trachyte spectral response of the soil quality, and the volcanic clastics development at 405 nm, 465 nm, 575 nm, 1105 nm. (2) Basaltic volcanic debris soil development, first deviation of maximum correlation coefficient is 0.8898; thick surface soil of the development of rocky volcanic debris from bottom reflectivity logarithm of first deviation of maximum correlation coefficient is 0.9029. (3) Soil organic matter content of basaltic volcanic clastics development optimal prediction model based on spectral reflectance inverse logarithms of first deviation of SMLR. Independent variable number is 7, Rv 2  = 0.9720, RMSEP = 2.0590, sig = 0.003. Trachyte qualitative volcanic clastics developed soil organic matter content of the optimal prediction model based on spectral reflectance inverse logarithms of first deviation of PLSR. Model number of the independent variables Pc = 5, Rc = 0.9872, Rc 2  = 0.9745, RMSEC = 0.4821, SEC = 0.4906, forecasts determine coefficient Rv 2  = 0.9702, RMSEP = 0.9563, SEP = 0.9711, Bias = 0.0637. Copyright © 2018 Elsevier B.V. All rights reserved.

The volcanic-sedimentary sequence of the Lousal deposit, Iberian Pyrite Belt (Portugal)

NASA Astrophysics Data System (ADS)

Rosa, Carlos; Rosa, Diogo; Matos, Joao; Relvas, Jorge

2010-05-01

The Iberian Pyrite Belt (IPB) is a massive sulfide province that is located in the south of Portugal and Spain, and hosts more than 90 massive sulfide deposits that amount to more than 1850 million metric tonnes of sulfide ore (Tornos, 2006). The ore deposits size, vary from ~1Mt to >100Mt (e.g. Neves Corvo and Aljustrel in Portugal, and Rio Tinto and Tharsis in Spain). The ore deposits are hosted by a submarine sedimentary and volcanic, felsic dominated, succession that constitutes the Upper Devonian to Lower Carboniferous Volcanic and Sedimentary Complex (VSC). The VSC ranges in thickness from approximately 600 to 1300 m (Tornos 2006). The VSC overlies the Phyllite-Quartzite Group (PQ) (Upper Devonian, base unknown) and is overlain by the Baixo Alentejo Flysch Group (Lower to Upper Carboniferous). The Lousal massive sulfide deposit is located in the western part of the IPB and occurs mostly interbedded with black mudstone. The VSC sequence at Lousal mine consists of a mudstone and quartzite sequence (PQ Group) in the lower part of the succession, over which a thick sequence of rhyolitic lavas (>300 m) occurs. Above the rhyolitic lavas there is a thick sequence of black and grey mudstone that hosts the massive sulfide ore bodies, and a rhyolitic sill. The upper part of the VSC sequence consists of a thick mudstone interval that hosts two thick basaltic units, locally with pillows. The rhyolites have small coherent cores, locally with flow bands, that grade to surrounding massive clastic intervals, with large lateral extent. The clasts show jigsaw-fit arrangement in many places and have planar or curviplanar margins and locally are perlitic at the margin. The top contact of these units is in most locations not exposed, which makes difficult to interpret the mode of emplacement. However, the thick clastic intervals, above described, are in accordance with quenching of volcanic glass with abundant water and therefore indicate that quenching of the rhyolites was the dominant fragmentation mechanism. Unlike many locations of the IPB, fiamme-rich pyroclastic units were not identified at Lousal. The ore deposits occur in close proximity with this volcanic centre that may have driven hydrothermal circulation that led to ore formation. The volcanic rocks show intense chloritic alteration, indicating that the mineralizing event occurred after most of the rhyolitic units have emplaced. The massive sulfides show abundant sedimentary structures which is not typical in the massive sulfide deposits of the IPB. The Lousal 50 Mt massive sulfide deposit consists of at least 11 ore bodies and was exploited until 1988 mainly for pyrite. The ores mined averaged 0.7% Cu, 0.8%Pb e 1.4%Zn (Strauss, 1971). These relatively low base metal grades led to an evaluation of the contents and distribution of high-tech element in the ore bodies, which would improve the economic viability of mining the deposit. This evaluation is currently focusing on the distribution and mineralogy of selenium, as ores mined in the past were known to be rich in this element. This work benefits from research projects INCA (PTDC/CTE-GIN/67027/2006; Characterization of crucial mineral resources for the development of renewable energy technologies: The Iberian Pyrite Belt ores as a source of indium and other high-technology elements) and project ARCHYMEDES II (POCTI/CTA/45873/2002), both funded by the Fundação para a Ciência e Tecnologia. REFERENCES Strauss, G.K., 1970. Sobre la geologia de la provincia piritifera del Suroeste de la Peninsula Iberica y sus yacimientos, en especial sobre la mina de pirita de Lousal (Portugal): Memoria del IGME 77, 1-266. Tornos, F., 2006. Environment of formation and styles of volcanogenic massive sulfides: The Iberian Pyrite Belt. Ore Geology Reviews 28, 259-307.

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

USGS Publications Warehouse

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

1982-01-01

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.

Surface wave tomography applied to the North American upper mantle

NASA Astrophysics Data System (ADS)

van der Lee, Suzan; Frederiksen, Andrew

Tomographic techniques that invert seismic surface waves for 3-D Earth structure differ in their definitions of data and the forward problem as well as in the parameterization of the tomographic model. However, all such techniques have in common that the tomographic inverse problem involves solving a large and mixed-determined set of linear equations. Consequently these inverse problems have multiple solutions and inherently undefinable accuracy. Smoother and rougher tomographic models are found with rougher (confined to great circle path) and smoother (finite-width) sensitivity kernels, respectively. A powerful, well-tested method of surface wave tomography (Partitioned Waveform Inversion) is based on inverting the waveforms of wave trains comprising regional S and surface waves from at least hundreds of seismograms for 3-D variations in S wave velocity. We apply this method to nearly 1400 seismograms recorded by digital broadband seismic stations in North America. The new 3-D S-velocity model, NA04, is consistent with previous findings that are based on separate, overlapping data sets. The merging of US and Canadian data sets, adding Canadian recordings of Mexican earthquakes, and combining fundamental-mode with higher-mode waveforms provides superior resolution, in particular in the US-Canada border region and the deep upper mantle. NA04 shows that 1) the Atlantic upper mantle is seismically faster than the Pacific upper mantle, 2) the uppermost mantle beneath Precambrian North America could be one and a half times as rigid as the upper mantle beneath Meso- and Cenozoic North America, with the upper mantle beneath Paleozoic North America being intermediate in seismic rigidity, 3) upper-mantle structure varies laterally within these geologic-age domains, and 4) the distribution of high-velocity anomalies in the deep upper mantle aligns with lower mantle images of the subducted Farallon and Kula plates and indicate that trailing fragments of these subducted oceanic plates still reside in the transition zone. The thickness of the high-velocity layer beneath Precambrian North America is estimated to be 250±70 km thick. On a smaller scale NA04 shows 1) high-velocities associated with subduction of the Pacific plate beneath the Aleutian arc, 2) the absence of expected high velocities in the upper mantle beneath the Wyoming craton, 3) a V-shaped dent below 150 km in the high-velocity cratonic lithosphere beneath New England, 4) the cratonic lithosphere beneath Precambrian North America being confined southwest of Baffin Bay, west of the Appalachians, north of the Ouachitas, east of the Rocky Mountains, and south of the Arctic Ocean, 5) the cratonic lithosphere beneath the Canadian shield having higher S-velocities than that beneath Precambrian basement that is covered with Phanerozoic sediments, 6) the lowest S velocities are concentrated beneath the Gulf of California, northern Mexico, and the Basin and Range Province.

Geohydrology and simulated ground-water flow in northwestern Elkhart County, Indiana

USGS Publications Warehouse

Arihood, L.D.; Cohen, D.A.

1998-01-01

In 1994, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency and the City of Elkhart, developed a ground-water model of the Elkhart, Indiana, area to determine the avail-ability and source of water at potential new well fields. The modeled area covered 190 square miles of northwestern Elkhart County and a small part of southern Michigan. Three Superfund sites and several other sites in this area are undergoing environmental cleanup. The model would be used to guide the location of well fields so that Superfund sites and environmental cleanup areas would not be within recharge areas for the well fields. The City of Elkhart obtains its water supply from two aquifers separated by a generally continuous confining unit. The upper aquifer is composed primarily of sand and gravel of glacial origin. Thickness of the upper aquifer ranges from 0 to 116 feet and averages 47 feet. The lower aquifer is composed of sand and gravel with interbedded lenses of silt and clay. Thickness of the lower aquifer ranges from 1 to 335 feet and averages 35 feet. The intervening confining unit is composed of silt and clay with interbedded sand and gravel; the confining unit ranges from 0 to 177 feet, with an average thickness of 27 feet. Flow through the aquifers is generally horizontal vertically downward from the upper aquifer, through the confining unit, and into the lower aquifer, except where flow is vertically upward at the St. Joseph River and other large streams. The hydraulic characteristics of the aquifers and confining unit were estimated by analyzing aquifer-test data from well drillers? logs and by calibration of the model. The horizontal hydraulic conductivity of the upper aquifer is 170 feet per day within about 1 mile of the St. Joseph and Elkhart Rivers and 370 feet per day at distances greater than about 1 mile. The horizontal hydraulic conductivity of the lower aquifer is 370 feet per day throughout the modeled area, with the exception of an area near the center of the modeled area where the horizontal hydraulic conductivity is 170 feet per day. Transmissivity of the lower aquifer increases generally from southwest to northeast; transmissivity values range from near 0 where the lower aquifer is absent to 57,000 square feet per day and average about 8,100 square feet per day. The vertical hydraulic conductivity of the confining unit is 0.07 feet per day; the vertical conductivity of the streambeds commonly is 1.0 foot per day and ranges from 0.05 foot per day to 50 feet per day. The areal recharge rate to the outwash deposits was determined by a base-flow separation technique to be 16 inches per year, and the areal recharge rate to the till was assumed to be 4 inches per year. A two-layer digital model was used to simulate flow in the ground-water system. The model was calibrated on the basis of historical water-use data, water-level records, and gain/loss data for streams during May and June 1979. The model was recalibrated with water-use data and water-level records from 1988. For 1979 data, 49 percent of the inflow to the model area is from precipitation and 46 percent is ground-water inflow across the model boundaries. Most of the ground-water inflow across the model boundary is from the north and east, which corresponds to high values of transmissivity?as high as 57,000 feet squared per day?in the model layers in the northern and eastern areas. Eighty-two percent of the ground-water discharge is to the streams; 5 percent of the ground-water discharge is to wells. Source areas and flow paths to the City of Elkhart public well fields are affected by the location of streams and the geology in the area. Flow to the North Well Field originates north-west of the well field, forms relatively straight flow paths, and moves southeast toward the well field and the St. Joseph River. Flow to the South Well Field begins mostly in the out-wash along Yellow Creek south of the well field, moves northward, and t

Integration of new geologic mapping and satellite-derived quartz mapping yields insights into the structure of the Roberts Mountains allochthon applicable to assessments for concealed Carlin-type gold deposits

USGS Publications Warehouse

Holm-Denoma, Christopher S.; Hofstra, Albert H.; Rockwell, Barnaby W.; Noble, Paula J.

2012-01-01

Geologic mapping and remote sensing across north-central Nevada enable recognition of a thick sheet of Middle and Upper Ordovician Valmy Formation quartzite that structurally overlies folded and faulted Ordovician through Devonian stratigraphic units of the Roberts Mountains allochthon. In the northern Independence Mountains and nearby Double Mountain area, the Valmy Formation is in fault contact with Ordovician through Silurian, predominantly clastic, sedimentary rocks of the Roberts Mountains allochthon that were deformed prior to, or during, emplacement of the Valmy thrust sheet. Similar structural relations are recognized discontinuously for 200 kilometers along the strike of the Roberts Mountains allochthon in mapping guided by regional remote-sensing-based (ASTER) quartz maps. Overall thicknesses of deformed Roberts Mountains allochthon units between the base of the Valmy and the top of underlying carbonate rocks that host large Carlin-type gold deposits varies on the order of hundreds of meters but is not known to exceed 700 meters. The base of the Valmy thrust sheet is a complimentary datum in natural resource exploration and mineral resource assessment for concealed Carlin-type gold deposits.

Preliminary report on the coal resources of the National Petroleum Reserve in Alaska

USGS Publications Warehouse

Martin, G.C.; Callahan, J.E.

1978-01-01

NPR-A, located on the Arctic slope of Northern Alaska, is underlain by a thick sequence of sedimentary rocks of Cretaceous age which attain a thickness of as much as 4600 m (15,000 feet). The bulk of the coal resources occurs in rocks of the Nanushuk Group of Early and Late Cretaceous age. The Nanushuk Group is a wedge-shaped unit of marginal marine and nonmarine rocks that is as thick as 3300 m (11,000 feet) just west of NPR-A. Within the reserve, coal occurs primarily in the middle and thicker portions of this clastic wedge and occurs stratigraphically in the upper half of the section. Specific data on individual coal beds or zones are scarce, and estimates of identified coal resources of about 49.5 billion tons represent a sampling of coal resources too small to give a realistic indication of the potential resources for an area so large. Estimates of undiscovered resources suggest hypothetical resources of between 330 billion and 3.3 trillion tons. The wide range in the undiscovered resource estimates reflects the scarcity and ambiguity of the available data but also suggests the presence of a potentially large coal resource.

Prelude of benthic community collapse during the end-Permian mass extinction in siliciclastic offshore sub-basin: Brachiopod evidence from South China

NASA Astrophysics Data System (ADS)

Wu, Huiting; He, Weihong; Weldon, Elizabeth A.

2018-04-01

Analysis of the Permian-Triassic palaeocommunities from basinal facies in South China provides an insight into the environmental deterioration occurring in the prelude to the mass extinction event. Quantitative and multivariate analyses on three brachiopod palaeocommunities from the Changhsingian to the earliest Triassic in basinal facies in South China have been undertaken in this study. Although the end-Permian extinction has been proved to be a one-stepped event, ecological warning signals appeared in the palaeocommunities long before the main pulse of the event. A brachiopod palaeocommunity turnover occurred in the upper part of the Clarkina changxingensis Zone, associated with a significant decrease of palaeocommunity diversity and brachiopod body size. During this turnover the dominant genera changed from Fusichonetes and Crurithyris (or/and Paracrurithyris) to the more competitive genus Crurithyris (or/and Paracrurithyris). The brachiopod palaeocommunity turnover was supposed to be triggered by the decreased marine primary productivity and increased volcanic activity. Moreover, such early warning signals are found not only in the deep-water siliceous facies, but also in the shallow-water clastic facies and carbonate rock facies in South China.

Late Miocene sedimentary environments in south-western Amazonia (Solimões Formation; Brazil)

PubMed Central

Gross, Martin; Piller, Werner E.; Ramos, Maria Ines; Douglas da Silva Paz, Jackson

2011-01-01

In Miocene times a vast wetland existed in Western Amazonia. Whereas the general development of this amazing ecosystem is well established, many questions remain open on sedimentary environments, stratigraphical correlations as well as its palaeogeographical configuration. Several outcrops located in a barely studied region around Eirunepé (SW Amazonas state, Brazil) were investigated to obtain basic sedimentological data. The observed deposits belong to the upper part of the Solimões Formation and are biostratigraphically dated to the Late Miocene. Vertically as well as laterally highly variable fine-grained clastic successions were recorded. Based on the lithofacies assemblages, these sediments represent fluvial deposits, possibly of an anastomosing river system. Sand bodies formed within active channels and dominant overbank fines are described (levees, crevasse splays/channels/deltas, abandoned channels, backswamps, floodplain paleosols). Lacustrine environments are restricted to local floodplain ponds/lakes. The mollusc and ostracod content as well as very light δ18O and δ13C values, measured on ostracod valves, refer to exclusively freshwater conditions. Based on palaeontological and geological results the existence of a long-lived lake (“Lake Pebas”) or any influx of marine waters can be excluded for that region during the Late Miocene. PMID:26523089

Late Miocene sedimentary environments in south-western Amazonia (Solimões Formation; Brazil).

PubMed

Gross, Martin; Piller, Werner E; Ramos, Maria Ines; Douglas da Silva Paz, Jackson

2011-08-01

In Miocene times a vast wetland existed in Western Amazonia. Whereas the general development of this amazing ecosystem is well established, many questions remain open on sedimentary environments, stratigraphical correlations as well as its palaeogeographical configuration. Several outcrops located in a barely studied region around Eirunepé (SW Amazonas state, Brazil) were investigated to obtain basic sedimentological data. The observed deposits belong to the upper part of the Solimões Formation and are biostratigraphically dated to the Late Miocene. Vertically as well as laterally highly variable fine-grained clastic successions were recorded. Based on the lithofacies assemblages, these sediments represent fluvial deposits, possibly of an anastomosing river system. Sand bodies formed within active channels and dominant overbank fines are described (levees, crevasse splays/channels/deltas, abandoned channels, backswamps, floodplain paleosols). Lacustrine environments are restricted to local floodplain ponds/lakes. The mollusc and ostracod content as well as very light δ 18 O and δ 13 C values, measured on ostracod valves, refer to exclusively freshwater conditions. Based on palaeontological and geological results the existence of a long-lived lake ("Lake Pebas") or any influx of marine waters can be excluded for that region during the Late Miocene.

Relationship between high- and low-grade Archean terranes: Implications for early Earth paleogeography

NASA Technical Reports Server (NTRS)

Eriksson, K. A.

1986-01-01

The Western Gneiss Terrain (WGT) of the Yilgarn Block, Western Australia was studied. The WGT forms an arcuate belt of Archean gneisses that flank the western margin of the Yilgarn Block. In general the WGT is composed of high-grade orthogneisses and paragneisses which contain supracrustal belts composed largely of siliciclastic metasediments and subordinate iron formation. The platformal nature of the metasedimentary belts and lack of obvious metavolcanic lithologies contrasts with the composition of typical Yilgarn greenstones to the east. Radiometric data from WGT rocks indicates that these rocks are significantly older than Yilgarn rocks to the east (less than 3.3 Ga) and this has led to the suggestion that the WGT represents sialic basement to Yilgarn granite-greenstone belts. The Mount Narryer region exposes the northernmost occurrence of high-grade metasediments within the WGT and consists of quartz-rich clastic metasediments at upper amphibolite to granulite grade. Most occurrences of supracrustal rocks in this region comprise isolated lenses within the gneissic basement. However, at Mount Narryer a unique sequence of metaclastics with preserved bedding provide an unusual window into the parentage of similar supracrustal bodies in this region.

Simulated Effects of Ground-Water Augmentation on the Hydrology of Round and Halfmoon Lakes in Northwestern Hillsborough County, Florida

USGS Publications Warehouse

Yager, Richard M.; Metz, P.A.

2004-01-01

Pumpage from the Upper Floridan aquifer in northwest Hillsborough County near Tampa, Florida, has induced downward leakage from the overlying surficial aquifer and lowered the water table in many areas. Leakage is highest where the confining layer separating the aquifers is breached, which is common beneath many of the lakes in the study area. Leakage of water to the Upper Floridan aquifer has lowered the water level in many lakes and drained many wetlands. Ground water from the Upper Floridan aquifer has been added (augmented) to some lakes in an effort to maintain lake levels, but the resulting lake-water chemistry and lake leakage patterns are substantially different from those of natural lakes. Changes in lake-water chemistry can cause changes in lake flora, fauna, and lake sediment composition, and large volumes of lake leakage are suspected to enhance the formation of sinkholes near the shoreline of augmented lakes. The leakage rate of lake water through the surficial aquifer to the Upper Floridan aquifer was estimated in this study using ground-water-flow models developed for an augmented lake (Round Lake) and non-augmented lake (Halfmoon Lake). Flow models developed with MODFLOW were calibrated through nonlinear regression with UCODE to measured water levels and monthly net ground-water-flow rates from the lakes estimated from lake-water budgets. Monthly estimates of ground-water recharge were computed using an unsaturated flow model (LEACHM) that simulated daily changes in storage of water in the soil profile, thus estimating recharge as drainage to the water table. Aquifer properties in the Round Lake model were estimated through transient-state simulations using two sets of monthly recharge rates computed during July 1996 to February 1999, which spanned both average conditions (July 1996 through October 1997), and an El Ni?o event (November 1997 through September 1998) when the recharge rate doubled. Aquifer properties in the Halfmoon Lake model were estimated through steady-state simulations of average conditions in July 1996. Simulated hydrographs computed by the Round and Halfmoon Lake models closely matched measured water-level fluctuations, except during El Ni?o, when the Halfmoon Lake model was unable to accurately reproduce water levels. Possibly, potential recharge during El Ni?o was diverted through ground-water-flow outlets that were not represented in the Halfmoon Lake model, or a large part of the rainfall was diverted into runoff before it could become recharge. Solute transport simulations with MT3D indicate that leakage of lake water extended 250 to 400 feet into the surficial aquifer around Round Lake, and from 75 to 150 feet around Halfmoon Lake before flowing to the underlying Upper Floridan aquifer. These results are in agreement with concentrations of stable isotopes of oxygen-18 (d18O) and deuterium (dD) in the surficial aquifer. Schedules of monthly augmentation rates to maintain constant stages in Round and Halfmoon Lakes were computed using an equation that accounted for changes in the Upper Floridan aquifer head and the deviation from the mean recharge rate. Resulting lake stages were nearly constant during the first half of the study, but increased above target lake stages during El Ni?o; modifying the computation of augmentation rates to account for the higher recharge rate during El Ni?o resulted in lake stages that were closer to the target lake stage. Substantially more lake leakage flows to the Upper Floridan aquifer from Round Lake than from Halfmoon Lake, because the estimated vertical hydraulic conductivities of lake and confining layer sediments and breaches in the confining layer beneath Round Lake are much greater. Augmentation rates required to maintain the low guidance stages in Round Lake (53 feet) and Halfmoon Lake (42 feet) under average Upper Floridan aquifer heads are estimated as 33,850 cubic feet per day and 1,330 to 10,000 cubic feet per day, respectively. T

Potentiometric surface of the Upper Floridan aquifer in Florida and parts of Georgia, South Carolina, and Alabama, May – June 2010

USGS Publications Warehouse

Kinnaman, Sandra L.; Dixon, Joann F.

2011-01-01

The Floridan aquifer system covers nearly 100,000 square miles in the southeastern United States throughout Florida and in parts of Georgia, South Carolina, and Alabama, and is one of the most productive aquifers in the world (Miller, 1990). This sequence of carbonate rocks is hydraulically connected and is over 300 feet thick in south Florida and thins toward the north. Typically, this sequence is subdivided into the Upper Floridan aquifer, the middle confining unit, and the Lower Floridan aquifer. The majority of freshwater is contained in the Upper Floridan aquifer and is used for water supply (Miller, 1986). The Lower Floridan aquifer contains fresh to brackish water in northeastern Florida and Georgia, while in south Florida it is saline. The potentiometric surface of the Upper Floridan aquifer in May–June 2010 shown on this map was constructed as part of the U.S. Geological Survey Floridan Aquifer System Groundwater Availability Study (U.S. Geological Survey database, 2011). Previous synoptic measurements and regional potentiometric maps of the Upper Floridan aquifer were prepared for May 1980 (Johnston and others, 1981) and May 1985 (Bush and others, 1986) as part of the Floridan Regional Aquifer System Analysis.

APPLICATIONS OF CATHODOLUMINESCENCE OF QUARTZ AND FELDSPAR TO SEDIMENTARY PETROLOGY.

USGS Publications Warehouse

Ruppert, Leslie F.

1987-01-01

Cathodoluminescence (CL), the emission of visible light during electron bombardment, was first used in sandstone petrology in the mid-1960's. CL techniques are especially useful for determining the origin and source of quartz and feldspar, two of the most common constituents in clastic rocks. CL properties of both minerals are dependent on their temperature of crystallization, duration of cooling, and/or history of deformation. Detrital quartz and feldspar are typically derived from igneous and metamorphic sources and luminesce in the visible range whereas authigenic quartz and feldspar form at low temperatures and do not luminesce. Quantification of luminescent and non-luminescent quartz and feldspar with the scanning electron microscope, electron microprobe, or a commercial CL device can allow for the determination of origin, diagenesis, and source of clastic rocks when used in conjunction with field and other petrographic analyses.

Perturbation of seafloor bacterial community structure by drilling waste discharge.

PubMed

Nguyen, Tan T; Cochrane, Sabine K J; Landfald, Bjarne

2018-04-01

Offshore drilling operations result in the generation of drill cuttings and localized smothering of the benthic habitats. This study explores bacterial community changes in the in the upper layers of the seafloor resulting from an exploratory drilling operation at 1400m water depth on the Barents Sea continental slope. Significant restructurings of the sediment microbiota were restricted to the sampling sites notably affected by the drilling waste discharge, i.e. at 30m and 50m distances from the drilling location, and to the upper 2cm of the seafloor. Three bacterial groups, the orders Clostridiales and Desulfuromonadales and the class Mollicutes, were almost exclusively confined to the upper two centimeters at 30m distance, thereby corroborating an observed increase in anaerobicity inflicted by the drilling waste deposition. The potential of these phylogenetic groups as microbial bioindicators of the spatial extent and persistence of drilling waste discharge should be further explored. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lithofacies and sequence stratigraphic description of the upper part of the Avon Park Formation and the Arcadia Formation in U.S. Geological Survey G–2984 test corehole, Broward County, Florida

USGS Publications Warehouse

Cunningham, Kevin J.; Robinson, Edward

2017-07-18

Rock core and sediment from U.S. Geological Survey test corehole G–2984 completed in 2011 in Broward County, Florida, provide an opportunity to improve the understanding of the lithostratigraphic, sequence stratigraphic, and hydrogeologic framework of the intermediate confining unit and Floridan aquifer system in southeastern Florida. A multidisciplinary approach including characterization of sequence stratigraphy, lithofacies, ichnology, foraminiferal paleontology, depositional environments, porosity, and permeability was used to describe the geologic samples from this test corehole. This information has produced a detailed characterization of the lithofacies and sequence stratigraphy of the upper part of the middle Eocene Avon Park Formation and Oligocene to middle Miocene Arcadia Formation. This enhancement of the knowledge of the sequence stratigraphic framework is especially important, because subaerial karst unconformities at the upper boundary of depositional cycles at various hierarchical scales are commonly associated with secondary porosity and enhanced permeability in the Floridan aquifer system.

Early Cretaceous stratigraphy, paleontology, and sedimentary tectonics in Paris overthrust foredeep (western Wyoming and southeastern Idaho) compared with Quaternary features of indo-gangetic plain

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

Dorr, J.A. Jr.

1983-08-01

Fluviatile clastics of the nonmarine, early Cretaceous Gannett and Wayan groups were deposited on wet alluvial megafans and on intervening interfan piedmont slopes which declined eastward into more poorly drained lowlands from a western highland source area uplifted episodically by movements of the Paris overthrust. Lacustrine episodes of deposition intercalated Peterson and Draney limestones with Gannett fluvial clastics. Westward marine transgressions (Skull Creek, Mowry) intercalated mixed lacustrine and brackish facies (Smiths and Cokedale formations) into Wayan fluviatile clastics. Newly discovered fossil vertebrate and invertebrate materials (all fragmentary but identifiable) include: Gannett Group - large reptiles including turtles; Thomas Fork Formationmore » - freshwater gastropods and unionid pelecypods, gastroliths, two types of turtles, large reptilian fragments (dinosaur), and abundant dinosaur eggshell fragments; Wayan Formation - perennially aquatic snails, turtles, unidentifiable large reptiles, two types of crocodilians, an iguanodontid dinosaur (Tenontosaurus), an ankylosaurian dinosaur, a large ornithopod dinosaur, gastroliths, abundant and ubiquitous dinosaur eggshell fragments (numerous types and sizes), and miscellaneous unidentifiable small vertebrate bone fragments. A census of analogous modern reptile reproductive behaviors supports the conclusion that the Wayan, and probably also the Gannett, alluvial fan environments were used as upland breeding grounds by dinosaurs and perhaps other reptiles. Comparison of these Early Cretaceous data with observations on the tectonic setting, sedimentology, and biology of the Quaternary indo-gangetic plain suggests many close analogies between the two sedimentary tectonic settings.« less

Controls on Middle Pennsylvanian peat-forming floras in the Eastern United States

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

Eble, C.F.

1992-01-01

Middle Pennsylvanian strata in the Central Appalachian Basin contain numerous coal beds that provide an opportunity to study changes in coal-spore floras on an intra- and inter-bed scale. Vertical spore abundance patterns within individual coal beds record the ecological dynamics, both biologic and edaphic, of peat-forming systems in this interval. Coal palynofloras of this interval show a stratigraphic change in composition. Early to Middle Pennsylvanian spore floras are largely dominated by Lycospora. Species of Densosporites, a small lycopsid genus, Granulatisporites, a fern/pteridosperm( )-allied genus, and Laevigatosporites, a calamite-related genus, commonly displace Lycospora vertically within these beds, reflecting patterns of ecologicalmore » succession. Spore floras from stratigraphically younger coal beds in this sequence exhibit similar intra-bed spore variation, but contain increased percentages of tree-fern spores, and tend to be more florally heterogeneous overall. Areas of clastic deposition within the swamps are also marked by changes in spore composition. These changes in coal palynology are paralleled by stratigraphic changes in coal appearance and associated strata composition. The proportion of dull'' coal lithotypes, frequency of clastic partings, and amount of coarse clastics in the enclosing strata all increase toward the top of this sequence. Climate may have been more important in determining the floral composition of Early through mid-Middle Pennsylvanian peat swamps, whereas climate, tectonics, and eustasy interacted to determine sediment volume and type in this interval.« less

Development of a Unified Hydrostratigraphic Framework for the Floridan Aquifer System in Central and Southern Florida

NASA Astrophysics Data System (ADS)

Reese, R. S.

2008-05-01

The mostly carbonate Floridan aquifer system (FAS) of central and southern Florida is a widely used resource with a complex hydrostratigraphic framework that is managed primarily in a subregional context according to water management jurisdictional boundaries. As use of the FAS increases, a consistent regional hydrostratigraphic framework is needed for effective management across these boundaries. Stratigraphic marker horizons within and near the top of FAS were delineated and mapped to develop a preliminary, correlative stratigraphic framework. This framework was used to identify and determine aquifers, subaquifers, and confining units and map their spatial distribution. These horizons are based on lithologic changes and geophysical log signatures identified in previous studies, and they were extended throughout the study area primarily by correlation of natural gamma-ray logs. The FAS consists of the Upper Floridan aquifer, middle confining unit, and Lower Floridan aquifer. A regional, productive zone is delineated and informally referred to as the Avon Park permeable zone. This zone is present over most of the study area and is characterized by thick units of dolostone with interbedded limestone and high fracture permeability. The zone has been identified in different regions in previous studies, either as the upper part of the Lower Floridan aquifer or as the lower part of the Upper Floridan aquifer. In this study it is generally considered to be within the middle confining unit. Transmissivity of the Avon Park permeable zone, a major source of water supply, generally ranges from less than 1x104 up to 1.6x106 ft2/day, and is greatest in central Florida where dolomite is developed as a major component of the zone. A large area of low transmissivity (less than 105 ft2/day) in southern Florida coincides with an area where limestone is the predominant lithology within the zone. Major uses of the FAS now include withdrawal for public and agricultural supply, including treatment with reverse osmosis, aquifer storage and recovery, and disposal of treated wastewater. Water-level and water-quality conflicts could arise between these competing uses, and delineating the extent and hydraulic connectivity of the Avon Park permeable zone within the FAS may help managers and others predict and minimize such conflicts.

An Evaluation of the Bouwer and Rice Method of Slug Test Analysis

NASA Astrophysics Data System (ADS)

Brown, David L.; Narasimhan, T. N.; Demir, Z.

1995-05-01

The method of Bouwer and Rice (1976) for analyzing slug test data is widely used to estimate hydraulic conductivity (K). Based on steady state flow assumptions, this method is specifically intended to be applicable to unconfined aquifers. Therefore it is of practical value to investigate the limits of accuracy of the K estimates obtained with this method. Accordingly, using a numerical model for transient flow, we evaluate the method from two perspectives. First, we apply the method to synthetic slug test data and study the error in estimated values of K. Second, we analyze the logical basis of the method. Parametric studies helped assess the role of the effective radius parameter, specific storage, screen length, and well radius on the estimated values of K. The difference between unconfined and confined systems was studied via conditions on the upper boundary of the flow domain. For the cases studied, the Bouwer and Rice analysis was found to give good estimates of K, with errors ranging from 10% to 100%. We found that the estimates of K were consistently superior to those obtained with Hvorslev's (1951) basic time lag method. In general, the Bouwer and Rice method tends to underestimate K, the greatest errors occurring in the presence of a damaged zone around the well or when the top of the screen is close to the water table. When the top of the screen is far removed from the upper boundary of the system, no difference is manifest between confined and unconfined conditions. It is reasonable to infer from the simulated results that when the screen is close to the upper boundary, the results of the Bouwer and Rice method agree more closely with a "confined" idealization than an "unconfined" idealization. In effect, this method treats the aquifer system as an equivalent radial flow permeameter with an effective radius, Re, which is a function of the flow geometry. Our transient simulations suggest that Re varies with time and specific storage. Thus the effective radius may be reasonably viewed as a time-averaged mean value. The fact that the method provides reasonable estimates of hydraulic conductivity suggests that the empirical, electric analog experiments of Bouwer and Rice have yielded shape factors that are better than the shape factors implicit in the Hvorslev method.

Molecular dynamics study on evaporation and condensation characteristics of thin film liquid Argon on nanostructured surface in nano-scale confinement

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Rabbi, Kazi Fazle; Sabah, Arefiny; Ahmed, Jannat; Kuri, Subrata Kumar; Rakibuzzaman, S. M.

2017-06-01

Investigation of Molecular level phase change phenomena are becoming important in heat and mass transfer research at a very high rate, driven both by the need to understand certain fundamental phenomena as well as by a plethora of new and forthcoming applications in the areas of micro- and nanotechnologies. Molecular dynamics simulation has been carried out to go through the evaporation and condensation characteristics of thin liquid argon film in Nano-scale confinement. In the present study, a cuboid system is modeled for understanding the Nano-scale physics of simultaneous evaporation and condensation. The cuboid system consists of hot and cold parallel platinum plates at the bottom and top ends. The fluid comprised of liquid argon film at the bottom plate and vapor argon in between liquid argon and upper plate of the domain. Three different simulation domains have been created here: (i) Both platinum plates are considered flat, (ii) Upper plate consisting of transverse slots of low height and (iii) Upper plate consisting of transverse slots of bigger height. Considering hydrophilic nature of top and bottom plates, two different high temperatures of the hot wall was set and an observation was made on normal and explosive vaporizations and their impacts on thermal transport. For all the structures, equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. Then the lower wall is set to two different temperatures like 110 K and 250 K for all three models to perform non-equilibrium molecular dynamics (NEMD). For vaporization, higher temperature of the hot wall led to faster transport of the liquid argon as a cluster moving from hot wall to cold wall. But excessive temperature causes explosive boiling which seems not good for heat transportation because of less phase change. In case of condensation, an observation was made which indicates that the nanostructured transverse slots facilitate condensation. Two factors affect the rate of condensation when nanostructures are there: (i) increased surface area and (ii) the nanostructure height. The variation of temperature and evaporation number with respect to time was monitored for all cases. An estimation of heat fluxes normal to top and bottom walls also was made to focus the effectiveness of heat transfer in hydrophilic confinement.

Pattern of external injuries sustained during bomb blast attacks in Karachi, Pakistan from 2000 to 2007.

PubMed

Surani, Arif Anwar; Ali, Salman; Surani, Asif; Zahid, Sohaib; Shoukat, Akber; Varon, Joseph; Surani, Salim

2015-07-01

To evaluate patterns of external injury resulting from bomb blasts in Karachi, and compare the injury profile resulting from explosions in open versus semi-confined blast environments. The retrospective, cross-sectional study was conducted in Karachi and comprised relevant data from January 2000 to October 2007. Casualty medical records and medico-legal certificates of the victims presented to three large public-sector hospitals were evaluated using a self-designed proforma. SPSS 17 was used for statistical analysis. Of the 1146 victims, data of 481(42%) represented the final study sample. Of these, 306(63.6%) were injured in open spaces and 175(36.4%) in semi-confined spaces. Of the 896 recorded injuries, lacerations were encountered as external injury in 427(47.7%) cases, followed by penetrating wounds in 137(15.3%). Lower and upper extremities were injured in 348(38.8%) and 170(19%) victims respectively. Open and semi-confined blast environments produced specific injury pattern and profile (p<0.001). External injuries sustained during bomb blast attacks in Karachi demonstrated specific injury patterns and profiles. Further studies are required to account for internal injuries and classification of injuries based on standardised scoring systems.

Hydrogeologic reconnaissance of the San Miguel River basin, southwestern Colorado

USGS Publications Warehouse

Ackerman, D.J.; Rush, F.E.

1984-01-01

The San Miguel River Basin encompasses 4,130 square kilometers of which about two-thirds is in the southeastern part of the Paradox Basin. The Paradox Basin is a part of the Colorado Plateaus that is underlain by a thick sequence of evaporite beds of Pennsylvanian age. The rock units that underlie the area have been grouped into hydrogeologic units based on their water-transmitting ability. Evaporite beds of mostly salt are both overlain and underlain by confining beds. Aquifers are present above and below the confining-bed sequence. The principal element of ground-water outflow from the upper aquifer is flow to the San Miguel River and its tributaries; this averages about 90 million cubic meters per year. A water budget for the lower aquifer has only two equal, unestimated elements, subsurface outflow and recharge from precipitation. The aquifers are generally isolated from the evaporite beds by the bounding confining beds; as a result, most ground water has little if any contact with the evaporites. No brines have been sampled and no brine discharges have been identified in the basin. Salt water has been reported for petroleum-exploration wells, but no active salt solution has been identified. (USGS)

Understanding fuel magnetization and mix using secondary nuclear reactions in magneto-inertial fusion.

PubMed

Schmit, P F; Knapp, P F; Hansen, S B; Gomez, M R; Hahn, K D; Sinars, D B; Peterson, K J; Slutz, S A; Sefkow, A B; Awe, T J; Harding, E; Jennings, C A; Chandler, G A; Cooper, G W; Cuneo, M E; Geissel, M; Harvey-Thompson, A J; Herrmann, M C; Hess, M H; Johns, O; Lamppa, D C; Martin, M R; McBride, R D; Porter, J L; Robertson, G K; Rochau, G A; Rovang, D C; Ruiz, C L; Savage, M E; Smith, I C; Stygar, W A; Vesey, R A

2014-10-10

Magnetizing the fuel in inertial confinement fusion relaxes ignition requirements by reducing thermal conductivity and changing the physics of burn product confinement. Diagnosing the level of fuel magnetization during burn is critical to understanding target performance in magneto-inertial fusion (MIF) implosions. In pure deuterium fusion plasma, 1.01 MeV tritons are emitted during deuterium-deuterium fusion and can undergo secondary deuterium-tritium reactions before exiting the fuel. Increasing the fuel magnetization elongates the path lengths through the fuel of some of the tritons, enhancing their probability of reaction. Based on this feature, a method to diagnose fuel magnetization using the ratio of overall deuterium-tritium to deuterium-deuterium neutron yields is developed. Analysis of anisotropies in the secondary neutron energy spectra further constrain the measurement. Secondary reactions also are shown to provide an upper bound for the volumetric fuel-pusher mix in MIF. The analysis is applied to recent MIF experiments [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] on the Z Pulsed Power Facility, indicating that significant magnetic confinement of charged burn products was achieved and suggesting a relatively low-mix environment. Both of these are essential features of future ignition-scale MIF designs.

Experimental demonstration of subwavelength domino plasmon devices for compact high-frequency circuit.

PubMed

Ma, Y G; Lan, L; Zhong, S M; Ong, C K

2011-10-24

In optical frequency, surface plasmons of metal provide us a prominent way to build compact photonic devices or circuits with non-diffraction limit. It is attributed by their extraordinary electromagnetic confining effect. But in the counterpart of lower frequencies, plasmonics behavior of metal is screened by eddy current induced in a certain skin depth. To amend this, spoof plasmons engineered by artificial structures have been introduced to mimic surface plasmons in these frequencies. But it is less useful for practical application due to their weak field confinement as manifested by large field decaying length in the upper dielectric space. Recently, a new type of engineered plasmons, domino plasmon was theoretically proposed to produce unusual field confinement and waveguiding capabilities that make them very attractive for ultra-compact device applications [Opt. Exp. 18, 754-764 (2010)]. In this work, we implemented these ideas and built three waveguiding devices based on domino plasmons. Their strong capabilities to produce versatile and ultra-compact devices with multiple electromagnetic functions have been experimentally verified in microwaves. And that can be extended to THz regime to pave the way for a new class of integrated wave circuits. © 2011 Optical Society of America

Sudbury Breccia (Canada): a product of the 1850 Ma Sudbury Event and host to footwall Cu Ni PGE deposits

NASA Astrophysics Data System (ADS)

Rousell, Don H.; Fedorowich, John S.; Dressler, Burkhard O.

2003-02-01

The Sudbury Structure, formed by meteorite impact at 1850 Ma, consists of three major components: (1) the Sudbury Basin; (2) the Sudbury Igneous Complex, which surrounds the basin as an elliptical collar; and (3) breccia bodies in the footwall known as Sudbury Breccia. In general, the breccia consists of subrounded fragments set in a dark, fine-grained to aphanitic matrix. A comparison of the chemical composition of host rocks, clasts and matrices indicates that brecciation was essentially an in-situ process. Sudbury Breccia forms irregular-shaped bodies or dikes that range in size from mm to km scale. Contacts with the host rocks are commonly sharp. The aspect ratio of most clasts is approximately 2 with the long axes parallel to dike walls. The fractal dimension (Dr)=1.55. Although there appears to be some concentration of brecciation within concentric zones, small Sudbury Breccia bodies within and outside these zones have more or less random strikes and steep dips. Sudbury Breccia bodies near an embayment structure tend to be subparallel to the base of the Sudbury Igneous Complex. Sudbury Breccia occurs as much as 80 km from the outer margin of the Sudbury Igneous Complex. In an inner zone, 5 to 15 km wide, breccia comprises 5% of exposed bedrock with an increase in brecciation intensity in embayment structures. Sudbury Breccia may be classified into three types based on the nature of the matrix: clastic, pseudotachylite and microcrystalline. Clastic Sudbury Breccia, the dominant type in the Southern Province, is characterized by flow-surface structures. Possibly, a sudden rise in pore pressure caused explosive dilation and fragmentation, followed by fluidization and flowage into extension fractures. Pseudotachylite Sudbury Breccia, mainly confined to Archean rocks, apparently formed by comminution and frictional melting. Microcrystalline Sudbury Breccia formed as a result of the thermal metamorphism, of the North Range footwall, by the Sudbury Igneous Complex. This produced a zone, approximately 1.2 km wide, wherein the matrix of the breccia either recrystallized or, locally, melted. An overprint of regional metamorphism obliterated contact effects in the South Range footwall. The Ni-Cu-PGE magmatic sulphide deposits may be classified into four types based on structural setting: Sudbury Igneous Complex-footwall contact, footwall, offset, and sheared deposits. Sudbury Breccia is the main host for footwall deposits (e.g., McCreedy East, Victor, Lindsley). Sudbury Breccia locally hosts mineralization in radial (e.g., Parkin and Copper Cliff) and concentric (e.g., Frood-Stobie) offset dikes.

Biological Responses in Rats Exposed to Cigarette Smoke and Middle East Sand (Dust)

DTIC Science & Technology

2012-01-01

surface dust (upper 10 mm of soil) was collected in an area no larger than 15.24 m × 15.24 m, and sampling was confined to local soil containing no fill...2004). Airway histopathology One day after the last sand exposure, necropsy was performed. Rats were anesthetized with sodium Iraqi sand toxicity 113...olfactory epithelial necrosis . During the light microscope examination, histopatho- logic diagnoses for tissues of each animal were recorded

Hydrogeology and predevelopment flow in the Texas Gulf Coast aquifer systems

USGS Publications Warehouse

Ryder, Paul D.

1988-01-01

Total simulated recharge in the outcrop areas is 269 million cubic feet per day, which is offset by an equal amount of discharge in the outcrop areas. The smallest rates of leakage are across the Vicksburg-Jackson confining unit, with downward and upward rates of less than one million cubic feet per day. The greatest rate of leakage is 47 million cubic feet per day upward into the Holocene-upper Pleistocene permeable zone.

Resonant-phonon-assisted THz quantum cascade lasers with metal-metal waveguides.

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

Callebaut, Hans; Kohen, Stephen; Kumar, Sushil

2004-06-01

We report our development of terahertz (THz) quantum-cascade lasers (QCLs) based on two novel features. First, the depopulation of the lower radiative level is achieved through resonant longitudinal optical (LO-)phonon scattering. This depopulation mechanism is robust at high temperatures and high injection levels. In contrast to infrared QCLs that also use LO-phonon scattering for depopulation, in our THz lasers the selectivity of the depopulation scattering is achieved through a combination of resonant tunneling and LO-phonon scattering, hence the term resonant phonon. This resonant-phonon scheme allows a highly selective depopulation of the lower radiative level with a sub-picosecond lifetime, while maintainingmore » a relatively long upper level lifetime (>5 ps) that is due to upper-to-ground-state scattering. The second feature of our lasers is that mode confinement is achieved by using a novel double-sided metal-metal waveguide, which yields an essentially unity mode confinement factor and therefore a low total cavity loss at THz frequencies. Based on these two unique features, we have achieved some record performance, including, but not limited to, the highest pulsed operating temperature of 137 K, the highest continuous-wave operating temperature of 97 K, and the longest wavelength of 141 {micro}m (corresponding to 2.1 THz) without the assistance of a magnetic field.« less

The combined use of 87Sr/86Sr and carbon and water isotopes to study the hydrochemical interaction between groundwater and lakewater in mantled karst

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Bullen, Thomas D.

1996-12-01

The hydrochemical interaction between groundwater and lakewater influences the composition of water that percolates downward from the surficial aquifer system through the underlying intermediate confining unit and recharges the Upper Floridan aquifer along highlands in Florida. The 87Sr/86Sr ratio along with the stable isotopes, D, 18O, and 13C were used as tracers to study the interaction between groundwater, lakewater, and aquifer minerals near Lake Barco, a seepage lake in the mantled karst terrane of northern Florida. Upgradient from the lake, the 87Sr/86Sr ratio of groundwater decreases with depth (mean values of 0.71004, 0.70890, and 0.70852 for water from the surficial aquifer system, intermediate confining unit, and Upper Floridan aquifer, respectively), resulting from the interaction of dilute oxygenated recharge water with aquifer minerals that are less radiogenic with depth. The concentrations of Sr2+ generally increase with depth, and higher concentrations of Sr2+ in water from the Upper Floridan aquifer (20-35 μg/L), relative to water from the surficial aquifer system and the intermediate confining unit, result from the dissolution of Sr-bearing calcite and dolomite in the Eocene limestone. Dissolution of calcite [δ13C= -1.6permil(‰)] is also indicated by an enriched δ13CDIC(-8.8 to -11.4 ‰) in water from the Upper Floridan aquifer, relative to the overlying hydrogeologic units (δ13CDIC< -16‰). Groundwater downgradient from Lake Barco was enriched in18O and D relative to groundwater upgradient from the lake, indicating mixing of lakewater leakage and groundwater. Downgradient from the lake, the 87Sr/86Sr ratio of groundwater and aquifer material become less radiogenic and the Sr2+ concentrations generally increase with depth. However, Sr2+ concentrations are substantially less than in upgradient groundwaters at similar depths. The lower Sr2+ concentrations result from the influence of anoxic lakewater leakage on the mobility of Sr2+ from clays. Based on results from mass-balance modeling, it is probable that cation exchange plays the dominant role in controlling the 87Sr/86Sr ratio of groundwater, both upgradient and downgradient from Lake Barco. Even though groundwater from the three distinct hydrogeologic units displays considerable variability in Sr concentration and isotopic composition, the dominant processes associated with the mixing of lakewater leakage with groundwater, as well as the effects of mineral-water interaction, can be ascertained by integrating the use of stable and radiogenic isotopic measurements of groundwater, lakewater, and aquifer minerals.

Geohydrologic systems in Kansas with emphasis on systems in Upper Cambrian through Lower Cretaceous rocks

USGS Publications Warehouse

Wolf, R.J.; Hansen, C.V.; McGovern, H.E.; Spinazola, J.M.

1990-01-01

This Hydrologic Investigations Atlas, which consists of a series of chapters, presents a description of (1) the physical frameworks and (2) the geohydrology of the principal aquifers and confining systems in Kansas. The report is the result of an investigation that has been made as part of the Central Midwest Regional Aquifer System Analysis (CMRASA), one of several major investigations by the U.S. Geological Survey to define regional aquifer systems. These regional analyses are designed to increase knowledge of major flow regimes and provide data for assessing, developing, and managing water supplies. The CMRASA is an investigation of water in Upper Cambrian through Lower Cretaceous rocks in parts of 10 Central Midwestern States, as shown by the map on the envelope cover.

Urban informality as a signifier: Performing urban reordering in suburban Rio de Janeiro

PubMed Central

Müller, Frank I

2017-01-01

Urban informality is typically ascribed to the urban poor in cities of the Global South. Drawing on Judith Butler’s concept of performativity and taking the case of Rio de Janeiro in the context of the 2016 Olympic Games, this article conceptualizes informality as a signifier and a procedural, relational category. Specifically, it shows how different class actors have employed the signifier informality (1) to legitimize the confinement of marginalized populations; (2) to justify the organized efforts of the upper middle class to protect their ‘self-enclosed’ gated communities; and (3) to warrant the formation of opposition and alliances between inhabitants, activists, and researchers on the edges of the urban order. This article offers new perspectives to better understand the relationship between informality and confinement by examining the active role that inhabitants of marginalized settlements assume in the Olympic City. PMID:28781405

Potentiometric surface of the Upper Floridan aquifer, west-central Florida, May 2005

USGS Publications Warehouse

Ortiz, A.G.; Blanchard, R.A.

2006-01-01

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is a highly productive aquifer and supplies more than 10 times the amount of water pumped from either the surficial aquifer system or the intermediate aquifer system in most of the study area (Duerr and others, 1988). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2005. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in a tightly cased well that taps a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 67.27 inches for west-central Florida (from June 2004 through May 2005) was 14.20 inches above the historical cumulative average of 53.07 inches (Southwest Florida Water Management District (SWFWMD), 2005). The above average precipitation is attributed to the active hurrican season for Florida in 2004. Historical cumulative averages are calculated from regional rainfall summary reports (1915 to the most recent completed calendar year) and are updated monthly by the SWFWMD. This report, prepared by the U.S. Geological Survey (USGS) in cooperation with the SWFWMD, is part of a semiannual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the USGS during May 23-27, 2005. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the SWFWMD boundary by the USGS office in Altamonte Springs, Florida (Kinnaman, 2006). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition. Water levels in about 19 percent of the wells measured in May 2005 were lower than the May 2004 water levels (Blanchard and others, 2004). Data from 409 wells indicate that the May 2005 water levels ranged from about 5 feet below to about 18 feet above the May 2004 water levels (fig. 1). The largest water-level declines occurred in southwestern Hernando County, northeastern Hillsborough County, and parts of Hillsborough, Sumter, and Sarasota Counties. The largest water-level rises occurred in southeastern Hillsborough County, eastern Manatee County, and western Hardee County (fig. 1). Water levels in about 95 percent of the wells measured in May 2005 were lower than the September 2004 water levels (Blanchard and Seidenfeld, 2005). Data from 405 wells indicate that the May 2005 water levels ranged from about 22 feet below to 14 feet above the September 2004 water levels. The largest water-level decline was in east-central Manatee County and the largest water-level rise was in central Sarasota County.

Devonian of the Northern Rocky Mountains and plains

USGS Publications Warehouse

Sandberg, Charles A.; Mapel, William J.

1967-01-01

5. Undivided uppermost Devonian (Famennian, to V-VI) and lowermost Mississippian (Tournaisian, cuI-lower cuIIα) carbonaceous and clastic rocks deposited in six shallow basins interspersed among areas uplifted during the penecontemporaneous Antler orogeny.

Tectonostratigraphic Evolution of the Levant domain since Late Palaeozoic: a Review

NASA Astrophysics Data System (ADS)

Barrier, Eric

2015-04-01

During the last 270 my, the evolution of the African/Arabian platform and margins in Levant and surroundings is controlled by a succession of regional tectonic events, starting with a rifting period in the late Paleozoic, and ending with the ongoing Arabia-Eurasia collision. The main rifting period initiated in the mid-late Permian and lasted until the early-Jurassic, as a consequence of the Pangea break up. During this period the Anatolian blocks are still attached to southern Pangea, but some of the Palmyra-Levant and East Mediterranean basins were initiating. From the Mid-Late Permian to the Early Triassic the sedimentation is clastic-dominated in the continental platforms and basins. In the Early Mesozoic, with the initiation and development of the Levant and East Mediterranean basins, the sedimentation changed from clastic to carbonate deposition. Widespread Triassic to Liassic sediments accumulated in subsiding basins (Levant, Palmyride, Sinjar) and margins (East Mediterranean Basin). The rifting aborted in the Palmyride Trough and Levant Basin in the early Jurassic, while the East Mediterranean Basin (Mesogea) the oceanic accretion probably developed during the mid-Jurassic. Then, a 60 My-long cycle lasted from the late Jurassic to the Turonian, mainly characterized by the thermal subsidence of main the basins and margins. Only the early Cretaceous is marked by an extensional tectonic event, associated with magmatism, widespread all around the East Mediterranean Basin. This event, together with the early Cretaceous eustatic regressions, originated a major stratigraphic gap with emersions at the top-Jurassic - Neocomian period, and the deposition of thick clastic sequences in grabens. The following Cenomanian - Early Turonian interval is a major transgressive period characterized by the extension of the carbonate platforms on the African platform, and subsidence of the margins. The Senonian is characterized by an increase in water depth, mainly resulting from the opening of NW- to WNW-oriented major Senonian grabens (e.g. the Sirt, Azraq and Euphrates grabens). The main pulse of rifting is Campanian in age. In the northeastern African plate this extensional tectonics is coeval with the obduction of the Neo-Tethyan ophiolites onto the Northern Arabian platform where thick flysch sequences deposited. Within the upper-most Maastrichtian to Paleocene times, some of the basins and margins were inverted, resulting in unconformities in some of the Mesozoic basins. A 1600 km long right lateral strike-slip zone developed in the southern Mesogean margin (Cyrenaica, northern Egypt, Negev). In the Eocene-Oligocene period a sub-meridian extension prevailed in the Levant area pre-dating the Arabia-Anatolia collision. Chalky deposits are widespread in the western Arabian platform, significantly thickening and deepening westward toward the Levant Basin. The Neogene period is dominated by compressive deformations following the closure of Eastern Mesogea, and related to the Arabia/Anatolia collision that initiated at the Oligocene-Miocene boundary. This period is marked by the inversion of the Mesozoic basins in the western Arabian plate (Afrin, Palmyrides, Sinjar) Finally, in the Late Miocene, a regional strike-slip fault system developed, including the Levant Fault, and the eastern and north Anatolian faults in Anatolia.

Evaporation characteristics of thin film liquid argon in nano-scale confinement: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

2016-07-01

Molecular dynamics simulation has been carried out to explore the evaporation characteristics of thin liquid argon film in nano-scale confinement. The present study has been conducted to realize the nano-scale physics of simultaneous evaporation and condensation inside a confined space for a three phase system with particular emphasis on the effect of surface wetting conditions. The simulation domain consisted of two parallel platinum plates; one at the top and another at the bottom. The fluid comprised of liquid argon film at the bottom plate and vapor argon in between liquid argon and upper plate of the domain. Considering hydrophilic and hydrophobic nature of top and bottom surfaces, two different cases have been investigated: (i) Case A: Both top and bottom surfaces are hydrophilic, (ii) Case B: both top and bottom surfaces are hydrophobic. For all cases, equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. Then the lower wall was set to four different temperatures such as 110 K, 120 K, 130 K and 140 K to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat fluxes normal to top and bottom walls were estimated and discussed to illuminate the effectiveness of heat transfer in both hydrophilic and hydrophobic confinement at various boundary temperatures of the bottom plate.

Water levels in, extent of freshwater in, and water withdrawal from eight major confined aquifers, New Jersey Coastal Plain, 1993

USGS Publications Warehouse

Lacombe, Pierre J.; Rosman, Robert

1997-01-01

Water levels in 722 wells in the Coastal Plain of New Jersey, Pennsylvania, and northeastern Delaware were measured during October and November 1993 and were used to define the potentiometric surface of the eight major confined aquifers of the area. Isochlors (lines of equal chloride concentration) for 250 and 10,000 milligrams per liter are included to show the extent of freshwater in each of the aquifers. Estimated water withdrawals from the eight major confined aquifers are reported for 1978-94. Water-withdrawal and water-level maps including isochlors were constructed for the Cohansey aquifer of Cape May County, the Atlantic City 800-foot sand, the Piney Point aquifer, the Wenonah-Mount Laurel aquifer, the Englishtown aquifer system, the Upper Potomac-Raritan-Magothy, the Middle and undifferentiated Potomac-Raritan-Magothy, and the Lower Potomac-Raritan-Magothy aquifers. From 1988 to 1993, water levels near the center of the large cones of depression in the Middlesex-Monmouth County area rose as much as 120 ft in the Wenonah-Mount Laurel aquifer and Englishtown aquifer system, 40 ft in the Upper Potomac-Raritan-Magothy aquifer, and 96 ft in the Middle and undifferentiated Potomac-Raritan-Magothy aquifers. Large cones of depression in the potentiometric surface of aquifers of the Potomac-Raritan-Magothy aquifer system in the Burlington-Camden-Gloucester area remained at about the same altitude; that is, the potentiometric surface neither rose nor fell in the aquifers by more than 5 feet. In the same area, water levels in the Englishtown aquifer system were static, whereas the water levels in the Wenonah-Mount Laurel aquifer declined 5 to 20 feet, forming an expanded cone of depression. Water levels in the Cohansey, Atlantic City 800-foot sand, and Piney Point aquifers declined by 1 to 10 feet during 1988?93.

Chronology of the late Turolian deposits of the Fortuna basin (SE Spain): implications for the Messinian evolution of the eastern Betics

NASA Astrophysics Data System (ADS)

Garcés, Miguel; Krijgsman, Wout; Agustí, Jorge

1998-11-01

The magnetostratigraphy of the mammal-bearing alluvial fan-fan delta sequences of the Fortuna basin (SE Spain) has yielded an accurate chronology for the late Turolian (Messinian) basin infill. From early to late Messinian (at least between 6.8 and 5.7 Ma), the Fortuna basin records the sedimentation of alluvial-palustrine deposits over a confined shallow basin. Changing environmental conditions in the latest Messinian are illustrated by the retreat of palustrine facies. A rapid progradation of the marginal clastic wedges and the initiation of an efficient basin drainage at ˜5.8 Ma (lower part of chron C3r) most likely represents the onshore response to the drastic drop of base level taking place during the Messinian salinity crisis. This study further provides improved age estimates for the late Turolian land mammal events in southern Spain. The oldest MN 13 locality in the studied sections is correlated to chron C3Ar at an age of 6.8 Ma. The entry of camels and the murid Paraethomys in southern Spain occurs in chron C3An.1n at 6.1 Ma, and gives further support for land mammal exchange between Africa and the Iberian peninsula prior to the salinity crisis, in good agreement with results from northern Africa [M. Benammi, M. Calvo, M. Prévot, J.J. Jaeger, Magnetostratigraphy and paleontology of Aı̈t Kandoula basin (High Atlas, Morocco) and the African-European late Miocene terrestrial fauna exchanges, Earth Planet. Sci. Lett. 145 (1996) 15-29]. The age of the studied sequences provides important constraints on the understanding of the sedimentary evolution of the eastern Betic margin, and shows that previous interpretations of the evaporitic-diatomitic sequences of the Fortuna basin, as being coeval to the late Messinian salinity crisis in the Mediterranean, are not correct. The confinement leading to the emergence of the Fortuna basin occurred in the late Tortonian to earliest Messinian, similar to other intramontane basins in the Betics. Therefore, the inclusion of the Fortuna basin in a hypothetical marine Betic Corridor during the late Messinian is no longer tenable.

Geochemical prospecting for copper and nickel in the Wulgai and Tor Tangi areas southeast of Hindubagh, Quetta Division, Pakistan

USGS Publications Warehouse

Stanin, S. Anthony; Wahid, M.A.; Khan, Shamsher

1975-01-01

Showings of magnetite, copper, and possible nickel mineralization in the Hindubagh chromite mining district are near Wulgai and Tor Tangi. Several hundred samples of clastic material from dry streambeds in these areas were sieved for the minus-80-mesh fraction and analyzed for copper using 2, 2'-biquinoline and for nickel using alpha-furildioxime. The copper threshold is 75 ppm, and the nickel threshold is 400 ppm. A geochemical map has been prepared that shows nine areas of anomalously high copper and six areas of high nickel. The nickel anomalies may represent secondary dispersion patterns derived from the erosion of nickeliferous ultramafic rocks of the Hindubagh intrusive complex. Copper showings in and near four of the anomalous copper areas indicate that detailed geological investigation and detailed geochemical sampling of rocks, soil, and unconsolidated clastic material are required to determine the source of the anomalies.

Oligocene lacustrine tuff facies, Abu Treifeya, Cairo-Suez Road, Egypt

NASA Astrophysics Data System (ADS)

Abdel-Motelib, Ali; Kabesh, Mona; El Manawi, Abdel Hamid; Said, Amir

2015-02-01

Field investigations in the Abu Treifeya area, Cairo-Suez District, revealed the presence of Oligocene lacustrine volcaniclastic deposits of lacustrine sequences associated with an Oligocene rift regime. The present study represents a new record of lacustrine zeolite deposits associated with saponite clay minerals contained within reworked clastic vitric tuffs. The different lithofacies associations of these clastic sequences are identified and described: volcaniclastic sedimentary facies represent episodic volcaniclastic reworking, redistribution and redeposition in a lacustrine environment and these deposits are subdivided into proximal and medial facies. Zeolite and smectite minerals are mainly found as authigenic crystals formed in vugs or crusts due to the reaction of volcanic glasses with saline-alkaline water or as alteration products of feldspars. The presence of abundant smectite (saponite) may be attributed to a warm climate, with alternating humid and dry conditions characterised by the existence of kaolinite. Reddish iron-rich paleosols record periods of non-deposition intercalated with the volcaniclastic tuff sequence.

Tectonic signatures on active margins

NASA Astrophysics Data System (ADS)

Hogarth, Leah Jolynn

High-resolution Compressed High-Intensity Radar Pulse (CHIRP) surveys offshore of La Jolla in southern California and the Eel River in northern California provide the opportunity to investigate the role of tectonics in the formation of stratigraphic architecture and margin morphology. Both study sites are characterized by shore-parallel tectonic deformation, which is largely observed in the structure of the prominent angular unconformity interpreted as the transgressive surface. Based on stratal geometry and acoustic character, we identify three sedimentary sequences offshore of La Jolla: an acoustically laminated estuarine unit deposited during early transgression, an infilling or "healing-phase" unit formed during the transgression, and an upper transparent unit. The estuarine unit is confined to the canyon edges in what may have been embayments during the last sea-level rise. The healing-phase unit appears to infill rough areas on the transgressive surface that may be related to relict fault structures. The upper transparent unit is largely controlled by long-wavelength tectonic deformation due to the Rose Canyon Fault. This unit is also characterized by a mid-shelf (˜40 m water depth) thickness high, which is likely a result of hydrodynamic forces and sediment grain size. On the Eel margin, we observe three distinct facies: a seaward-thinning unit truncated by the transgressive surface, a healing-phase unit confined to the edges of a broad structural high, and a highly laminated upper unit. The seaward-thinning wedge of sediment below the transgressive surface is marked by a number of channels that we interpret as distributary channels based on their morphology. Regional divergence of the sequence boundary and transgressive surface with up to ˜8 m of sediment preserved across the interfluves suggests the formation of subaerial accommodation during the lowstand. The healing-phase, much like that in southern California, appears to infill rough areas in the transgressive surface. Reflectors within the laminated upper unit exhibit divergence towards the Eel River Syncline, which suggests that deposition in the syncline is syntectonic. The transgressive surface is offset across the Eureka Anticline indicating deformation has occurred since ˜10 ka. The relief observed along the transgressive surface is consistent with deformation rates measured onshore.

Geologic framework and hydrogeologic characteristics of the Edwards aquifer, Uvalde County, Texas

USGS Publications Warehouse

Clark, Allan K.

2003-01-01

The Edwards aquifer in Uvalde County is composed of Lower Cretaceous carbonate (mostly dolomitic limestone) strata of the Devils River Formation in the Devils River trend and of the West Nueces, McKnight, and Salmon Peak Formations in the Maverick basin. Rocks in the Devils River trend are divided at the bottom of the Devils River Formation into the (informal) basal nodular unit. Maverick basin rocks are divided (informally) into the basal nodular unit of the West Nueces Formation; into lower, middle, and upper units of the McKnight Formation; and into lower and upper units of the Salmon Peak Formation. The Edwards aquifer overlies the (Lower Cretaceous) Glen Rose Limestone, which composes the lower confining unit of the Edwards aquifer. The Edwards aquifer is overlain by the (Upper Cretaceous) Del Rio Clay, the basal formation of the upper confining unit. Upper Cretaceous and (or) Lower Tertiary igneous rocks intrude all stratigraphic units that compose the Edwards aquifer, particularly in the southern part of the study area.The Balcones fault zone and the Uvalde salient are the principal structural features in the study area. The fault zone comprises mostly en echelon, high-angle, and down-to-the-southeast normal faults that trend mostly from southwest to northeast. The Uvalde salient—resulting apparently from a combination of crustal uplift, diverse faulting, and igneous activity—elevates the Edwards aquifer to the surface across the central part of Uvalde County. Downfaulted blocks associated with six primary faults—Cooks, Black Mountain, Blue Mountain, Uvalde, Agape, and Connor—juxtapose the Salmon Peak Formation (Lower Cretaceous) in central parts of the study area against Upper Cretaceous strata in the southeastern part.The carbonate rocks of the Devils River trend and the Maverick basin are products of assorted tectonic and depositional conditions that affected the depth and circulation of the Cretaceous seas. The Devils River Formation formed in a fringing carbonate bank—the Devils River trend— in mostly open shallow marine environments of relatively high wave and current energy. The West Nueces, McKnight, and Salmon Peak Formations resulted mostly from partly restricted to open marine, tidal-flat, and restricted deep-basinal environments in the Maverick basin.The porosity of the Edwards aquifer results from depositional and diagenetic effects along specific lithostratigraphic horizons (fabric selective) and from structural and solutional features that can occur in any lithostratigraphic horizon (non-fabric selective). In addition to porosity depending upon the effects of fracturing and the dissolution of chemically unstable (soluble) minerals and fossils, the resultant permeability depends on the size, shape, and distribution of the porosity as well as the interconnection among the pores. Upper parts of the Devils River Formation and the upper unit of the Salmon Peak Formation compose some of the most porous and permeable rocks in Uvalde County.

A new method for estimating the turbulent heat flux at the bottom of the daily mixed layer

NASA Technical Reports Server (NTRS)

Imawaki, Shiro; Niiler, Pearn P.; Gautier, Catherine H.; Knox, Robert A.; Halpern, David

1988-01-01

Temperature data in the mixed layer and net solar irradiance data at the sea surface are used to estimate the vertical turbulent heat flux at the bottom of the daily mixed layer. The method is applied to data obtained in the eastern tropical Pacific, where the daily cycle in the temperature field is confined to the upper 10-25 m. Equatorial turbulence measurements indicate that the turbulent heat flux is much greater during nighttime than daytime.

The oldest micropepline beetle from Cretaceous Burmese amber and its phylogenetic implications (Coleoptera: Staphylinidae)

NASA Astrophysics Data System (ADS)

Cai, Chen-Yang; Huang, Di-Ying

2014-10-01

The staphylinid subfamily Micropeplinae includes small strongly sclerotized beetles with truncate elytra leaving the most part of abdomen exposed. Fossil micropeplines are rare and confined to Cenozoic representatives of extant genera. Here, we describe the oldest micropepline, Protopeplus cretaceus gen. and sp. n., from the Upper Cretaceous Burmese amber. Fluorescence microscope and confocal laser scanning microscopy (CLSM) were both used to reveal diagnostic features of Micropeplinae and some primitive traits that place Protopeplus very basally within Micropeplinae.

External Factors, Produced by Growing Nerves, Trigger a Regenerative Response in a Non-Regenerative Central Nervous System: Purification and Mode of Action

DTIC Science & Technology

1989-06-01

regenerating optic nerve CNS - Central nervous system FCS - Fetal calf serum Galc - Galactocerebroside G AP - Glial fibriliary acidic protein NGF...nent confinment of the casualty to a wheel chair. Laceration in the upper spinal cord leads to paralysis of the four limbs and a cut in the optic...of microtiter plates in Dulbecco’s modified Eagle medium (DVIEM) containing 10% fetal calf serum (FCS). When the cells reached confluency the medium

A Determination of Air-Sea Gas Exchange and Upper Ocean Biological Production From Five Noble Gases and Tritiugenic Helium-3

DTIC Science & Technology

2007-09-01

limitations due to so-called "bottle effects" produced by confining production to a single bottle, eliminating grazers, trace metal contamination from the...1, b - 2/3) (Levich, 1962 ) or can be determined by modeling studies of characteristic bubble populations (a = 0.7, b = 0.35) (Keeling, 1993). In this...artifacts associated with the early sampling method. In addition, some of the samples with large supersaturations may have been contaminated with

A regional view of urban sedimentary basins in Northern California based on oil industry compressional-wave velocity and density logs

USGS Publications Warehouse

Brocher, T.M.

2005-01-01

Compressional-wave (sonic) and density logs from 119 oil test wells provide knowledge of the physical properties and impedance contrasts within urban sedimentary basins in northern California, which is needed to better understand basin amplification. These wire-line logs provide estimates of sonic velocities and densities for primarily Upper Cretaceous to Pliocene clastic rocks between 0.1 - and 5.6-km depth to an average depth of 1.8 km. Regional differences in the sonic velocities and densities in these basins largely 1reflect variations in the lithology, depth of burial, porosity, and grain size of the strata, but not necessarily formation age. For example, Miocene basin filling strata west of the Calaveras Fault exhibit higher sonic velocities and densities than older but finer-grained and/or higher-porosity rocks of the Upper Cretaceous Great Valley Sequence. As another example, hard Eocene sandstones west of the San Andreas Fault have much higher impedances than Eocene strata, mainly higher-porosity sandstones and shales, located to the east of this fault, and approach those expected for Franciscan Complex basement rocks. Basement penetrations define large impedence contrasts at the sediment/basement contact along the margins of several basins, where Quaternary, Pliocene, and even Miocene deposits directly overlie Franciscan or Salinian basement rocks at depths as much as 1.7 km. In contrast, in the deepest, geographic centers of the basins, such logs exhibit only a modest impedance contrast at the sediment/basement contact at depths exceeding 2 km. Prominent (up to 1 km/sec) and thick (up to several hundred meters) velocity and density reversals in the logs refute the common assumption that velocities and densities increase monotonically with depth.

Late Quaternary denudation, Death and Panamint Valleys, eastern California

USGS Publications Warehouse

Jayko, A.S.

2005-01-01

Late Quaternary denudation rates are constrained from alluvial fans and tributary watersheds in central Death and Panamint Valleys. Preliminary results suggest that the denudation rate is in part a function of the mean watershed elevation. Rainfall increases semi-logarithmically with higher elevation to about 2500 m where it becomes limited by the regional average maximum moisture content of the air mass. The fan volumes show a power-law relation to the watershed areas. The fan volumes ranged from about 250,000 to 4000 km3 and the watershed areas range from about 60,000 to 2000 km2. The upper limit of the denudation rates estimated from small Death Valley fans restricted to the east side of the basin along the Black Mountain frontal scarp range between about 0.03 to 0.18 mm/yr. The maximum is made by assuming most of the clastic accumulation in these fans followed the last highstand of Lake Manly around 24,000 yr which is the least conservative condition. The upper limit of the denudation rates from the Panamint fans range from 0.04 to 0.20 mm/yr assuming the accumulation mainly postdates OIS-4 ???60,000 yr or OIS-2 ???20,000 yr based on the presence or absence of inset shorelines from the last glacial-pluvial maximum. The greater denudation rate associated with the higher mean watershed elevations can mainly be attributed to the greater rainfall at higher elevation. Denudation rates are about a third or less of the Neogene dip-slip rates reported from nearby active faults consistent with relief increasing during dryer periods. ?? 2005 Elsevier B.V. All rights reserved.

The silicon isotope composition of the upper continental crust

NASA Astrophysics Data System (ADS)

Savage, Paul S.; Georg, R. Bastian; Williams, Helen M.; Halliday, Alex N.

2013-05-01

The upper continental crust (UCC) is the major source of silicon (Si) to the oceans and yet its isotopic composition is not well constrained. In an effort to investigate the degree of heterogeneity and provide a robust estimate for the average Si isotopic composition of the UCC, a representative selection of well-characterised, continentally-derived clastic sediments have been analysed using high-precision MC-ICPMS. Analyses of loess samples define a narrow range of Si isotopic compositions (δ30Si = -0.28‰ to -0.15‰). This is thought to reflect the primary igneous mineralogy and predominance of mechanical weathering in the formation of such samples. The average loess δ30Si is -0.22 ± 0.07‰ (2 s.d.), identical to average granite and felsic igneous compositions. Therefore, minor chemical weathering does not resolvably affect bulk rock δ30Si, and loess is a good proxy for the Si isotopic composition of unweathered, crystalline, continental crust. The Si isotopic compositions of shales display much more variability (δ30Si = -0.82‰ to 0.00‰). Shale Si isotope compositions do not correlate well with canonical proxies for chemical weathering, such as CIA values, but do correlate negatively with insoluble element concentrations and Al/Si ratios. This implies that more intensive or prolonged chemical weathering of a sedimentary source, with attendant desilicification, is required before resolvable negative Si isotopic fractionation occurs. Shale δ30Si values that are more positive than those of felsic igneous rocks most likely indicate the presence of marine-derived silica in such samples. Using the data gathered in this study, combined with already published granite Si isotope analyses, a weighted average composition of δ30Si = -0.25 ± 0.16‰ (2 s.d.) for the UCC has been calculated.

A data reconnaissance on the effect of suspended-sediment concentrations on dissolved-solids concentrations in rivers and tributaries in the Upper Colorado River Basin

USGS Publications Warehouse

Tillman, Fred D.; Anning, David W.

2014-01-01

The Colorado River is one of the most important sources of water in the western United States, supplying water to over 35 million people in the U.S. and 3 million people in Mexico. High dissolved-solids loading to the River and tributaries are derived primarily from geologic material deposited in inland seas in the mid-to-late Cretaceous Period, but this loading may be increased by human activities. High dissolved solids in the River causes substantial damages to users, primarily in reduced agricultural crop yields and corrosion. The Colorado River Basin Salinity Control Program was created to manage dissolved-solids loading to the River and has focused primarily on reducing irrigation-related loading from agricultural areas. This work presents a reconnaissance of existing data from sites in the Upper Colorado River Basin (UCRB) in order to highlight areas where suspended-sediment control measures may be useful in reducing dissolved-solids concentrations. Multiple linear regression was used on data from 164 sites in the UCRB to develop dissolved-solids models that include combinations of explanatory variables of suspended sediment, flow, and time. Results from the partial t-test, overall likelihood ratio, and partial likelihood ratio on the models were used to group the sites into categories of strong, moderate, weak, and no-evidence of a relation between suspended-sediment and dissolved-solids concentrations. Results show 68 sites have strong or moderate evidence of a relation, with drainage areas for many of these sites composed of a large percentage of clastic sedimentary rocks. These results could assist water managers in the region in directing field-scale evaluation of suspended-sediment control measures to reduce UCRB dissolved-solids loading.

The Miocene Sommières basin, SE France: Bioclastic carbonates in a tide-dominated depositional system

NASA Astrophysics Data System (ADS)

Reynaud, Jean-Yves; James, Noël P.

2012-12-01

The Miocene Sommières Basin in SE France is a semi-enclosed depression that was connected to the Mediterranean Sea by a flooded paleo-incised valley and then filled by a suite of sediments comprising carbonate grains coming from temperate factories that were largely deposited in tidal-dominated paleoenvironments. The strata are partitioned into two sequences that reflect repeated flooding of the incised valley system, one of several similar situations in this region of France. The carbonate grains are mostly bioclasts, namely from barnacles, bryozoans, coralline algae (encrusting, branching, and rhodoliths), echinoids, and benthic foraminifers (large and small) with ostracods, sponge spicules and planktic foraminifers prominent in muddy facies. Particles were produced by shallow water carbonate factories on hard substrates (valley walls in particular), associated with subaqueous dunes, and in deeper water basinal settings. Each depositional sequence is underlain by an eroded and bored hard surface that is progressively overlain by TST subaqueous tidal dunes or storm deposits that grade up, in one case, into HST marls (the HST of the upper sequence has been removed by erosion). The lower sequence is ebb tide dominated whereas the upper sequence is flood tide dominated. The succession is interpreted to represent a TST whose tidal currents were focused by the narrow valley and a HST that reflected flooding of the overbanks. This stratigraphic and depositional motif is comparable to that in other spatially separated Neogene paleovalleys that are filled with tide-dominated clastic carbonates in the region. Together with other recently documented similar systems, these limestones constitute an important new group of carbonate sand bodies in the carbonate depositional realm.

Submarine landslide identified in DLW3102 core of the northern continental slope, South China Sea

NASA Astrophysics Data System (ADS)

Xu, Yuanqin; Liu, Lejun; Zhou, Hang; Huang, Baoqi; Li, Ping; Ma, Xiudong; Dong, Feiyin

2018-02-01

In this paper, we take DLW3101 core obtained at the top of the canyon (no landslide area) and DLW3102 core obtained at the bottom of the canyon (landslide area) on the northern continental slope of the South China Sea as research objects. The chronostratigraphic framework of the DLW3101 core and elemental strata of the DLW3101 core and the DLW3102 core since MIS5 are established by analyzing oxygen isotope, calcium carbonate content, and X-Ray Fluorescence (XRF) scanning elements. On the basis of the information obtained by analyzing the sedimentary structure and chemical elements in the landslide deposition, we found that the DLW3102 core shows four layers of submarine landslides, and each landslide layer is characterized by high Si, K, Ti, and Fe contents, thereby indicating terrigenous clastic sources. L1 (2.15-2.44 m) occurred in MIS2, which is a slump sedimentary layer with a small sliding distance and scale. L2 (15.48-16.00 m) occurred in MIS5 and is a debris flow-deposited layer with a scale and sliding distance that are greater than those of L1. L3 (19.00-20.90 m) occurred in MIS5; its upper part (19.00-20.00 m) is a debris flow-deposited layer, and its lower part (20.00-20.90 m) is a sliding deposition layer. The landslide scale of L3 is large. L4 (22.93-24.27 m) occurred in MIS5; its upper part (22.93-23.50 m) is a turbid sedimentary layer, and its lower part (23.50-24.27 m) is a slump sedimentary layer. The landslide scale of L4 is large.

Development of low-ash, planar peat swamps in an alluvial-plain setting: The no. 5 Block beds (westphalian D) of southern West Virginia

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

Staub, J.R.; Richards, B.K.

1993-07-01

Coals from the No. 5 Block coal beds (Westphalian D) of the central Appalachian basin are noted for their blocky, dull character and their low ash and low sulfur content. The beds are multiple benched, with rock partings separating benches. Individual benches have limited lateral extent and, where thick, are dominated by bright, high-ash coal at the base and dull, low-ash coal in the upper parts. The duller coals contain more exinite-group and inertinite-group macerals than the brighter coals. These coal beds are encased in sandstone units dominated by fining-upward sequences. The overall depositional setting is an alluvial-plain environment withmore » northwest-flowing channels spaced approximately 20 km apart. The channels were flanked by clastic swamps about 7 km wide. Low-ash peat accumulated in areas of the flood plain most distant from the channels. These peat-accumulating swamps were about 8 km across. In a few instances low-frequency flood events introduced fine siliciclastic sediment into the peat swamps, depositing a thin layer of sediment on top of the peat. This sediment layer is thicker where the underlying coal is the thickest. These thick coal areas are topographically lower than surrounding coal areas. This relationship between coal thickness, parting thickness, and topography indicates that these peat swamps were planar at the time of deposition. Individual coal benches contain abundant preserved cellular tissue (telocollinite, semifusinite, and fusinite) at most locations, suggesting that robust vegetation was widespread in the swamps and that the morphology was planar. The high concentrations of exinite-group an inertinite-group macerals in the upper parts of benches resulted from selective decomposition and oxidation of the peat in subaerial and aquatic planar-swamp environments.« less

Low ash, planar peat swamp development in an alluvial plain setting: The No. 5 block beds of southern West Virginia

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

Staub, J.R.; Richards, B.K.

1992-01-01

Coals from the No. 5 Block beds (Westphalian D) are noted for their low ash and sulfur content. Beds are multiple benched, with rock partings separating individual benches. Benches have limited continuity and, where thick are dominated by bright, high ash coal at the base and dull, low ash coal in their upper portions. The duller coals contain more exinite and inertinite group macerals than the brighter coals. The depositional setting is an alluvial plain environment with channel systems separated by distances of about 20 km. The channel systems were flanked by clastic swamps for distances of up to 7more » km or more on either side. Areas of flood plain most distant from the channels were sites where peat accumulated and these zones were about 8 km across. High energy, low frequency flood events introduced fine grained sediment into the peat swamps resulting in thin layers of sediment being deposited on top of the peat. These sediment layers are thicker in areas where the underlying coal is the thickest. These thick coal areas are topographically negative. This relationship between coal and parting thickness and topography indicates that these peat swamps were low-lying or planar. Individual coal benches contain abundant amounts of preserved cellular tissue (telocollinite, semifusinite, fusinite) at most locations indicating that woody arborescent like vegetation was widespread in the swamps suggesting a planar morphology. The high concentrations of exinite and inertinite group macerals found in the upper portions of individual benches resulted from decomposition and oxidation of the peat in subaerial to aquatic planar swamp environments.« less

Salt-water encroachment, geology, and ground-water resources of Savannah area, Georgia and South Carolina

USGS Publications Warehouse

Counts, H.B.; Donsky, Ellis

1964-01-01

The Savannah area consists of about 2,300 square miles of the Coastal Plain along the coast of eastern Georgia and southeastern South Carolina. Savannah is near the center of the area. Most of the large ground-water developments are in or near Savannah. About 98 percent of the approximately 60 mgd of ground water used is pumped from the principal artesian aquifer, which is composed of about 600 feet of limestone of middle Eocene, Oligocene, and early Miocene ages. Industrial and other wells of large diameter yield as much as 4,200 gpm from the principal artesian aquifer. Pumping tests and flow-net analyses show that the coefficient of transmissibility averages about 200,000 gpd per ft in the immediate Savannah area. The specific capacity of wells in the principal artesian aquifer generally is about 50 gpm per ft of drawdown. The coefficient of storage of the principal artesian aquifer is about 0.0003 in the Savannah area. Underlying the Savannah area are a series of unconsolidated and semiconsolidated sediments ranging in age from Late Cretaceous to Recent. The Upper Cretaceous, Paleocene, and lower Eocene sediments supply readily available and usable water in other parts of the Coastal Plain, but although the character and physical properties of these formations are similar in the Savannah area to the same properties in other areas, the hydraulic and structural conditions appear to be different. Deep test wells are needed to evaluate the ground-water potential of these rocks. The lower part of the sediments of middle Eocene age acts as a confining layer to the vertical movement of water into or out of the principal artesian aquifer. Depending on the location and depth, the principal artesian aquifer consists of from one to five geologic units. The lower boundary of the aquifer is determined by a reduction in permeability and an increase in salt-water content. Although the entire limestone section is considered water bearing, most of the ground water used in the area comes from the upper part of the Ocala limestone of late Eocene age and the limestones of Oligocene age. The greatest volume of water comes from the upper part of the Ocala limestone, but the greatest number of wells are supplied from the rocks of Oligocene age. The Tampa limestone and Hawthorn formation of early Miocene age are generally water bearing; the amount and quality of the water depends on the location. The water from some wells in the Tampa and most of the water from the Hawthorn is high in hydrogen sulfide. In the northeastern part of the area the principal artesian aquifer is close to the land surface. Here the confining layer is thin and in some of the estauaries it may be completely cut through by the scouring action of the streams during tidal fluctuations. In this part of the area artesian groundwater at one time discharged from the aquifer as submarine springs. Now a reverse effect may be occurring; ocean and river water may be entering the aquifer. The silts, clays, and very fine sands of the upper Miocene and Pliocene ( ?) series generally have low permeabilities and form the upper confining layer for the principal artesian aquifer. Although all the sediments overlying the principal artesian aquifer are considered to be part of the confining layer, locally some of the upper units are water bearing. The uppermost geologic units in the Savannah area are sediments of Pliocene ( ?) to Recent age and consist of sands, silts, and clays with shell and gravel beds which are a source of water for shallow wells. The first large ground-water supply from the principal artesian aquifer was developed in 1886 by the city of Savannah. Additional municipal and industrial supplies have been developed since that time. Pumpage progressively increased to a peak of 62 mgd in 1957. Outside of the city and industrial area the 1957 pumpage was about 9 mgd. In 1958 the total pumpage in the Savannah area was about 68 mgd or about 3 mgd less th

Complex carbonate and clastic stratigraphy of the inner shelf off west-central Florida

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

Locker, S.D.; Doyle, L.J.; Hine, A.C.

1990-05-01

The near surface stratigraphy (< 30 m) of the inner shelf off the west coast of Florida was investigated using high-resolution seismic, side-scan sonar, and continuous underwater video camera coverage. The simultaneous operation of all three systems provided a unique opportunity to calibrate acoustic data with actual video images of the sea floor in a geologically complex area characterized by limestone dissolution structures, hard-bottom exposures, and overlain by a limited supply of terrigenous clastics. Three principle bottom types, grass, sand, and hard-bottom mapped using video and side-scan sonographs, show a correlation with two subsurface stratigraphic zones. The nearshore subsurface zonemore » extending to 6-7 m water depth is characterized by flat or rolling strata and sinkholes that increase in size (200-1,200 m in diameter) and become more numerous further offshore. This zone is truncated by a major erosional unconformity overlain by a thin (<3 m) sequence of Holocene sediment, which together form a terrace upon which the Anclote Key barrier island formed. The offshore subsurface zone (7-11 m water depth) exhibits irregular and discontinuous high-amplitude flat or inclined reflections and few sinkholes. Offshore, extensive hard-bottom exposures are common with discontinuous sediment that occur as lenses or sand waves. The complex stratigraphy of the west Florida shelf includes outcropping Neogene limestones that have undergone dissolution during sea level lowstands. Carbonates and clastics dispersed during multiple sea level changes overlie the Neogene limestones. Dissolution styles and erosional unconformities produced bedrock topography and now control modern geological and biological processes.« less

Lower Cretaceous Avile Sandstone, Neuquen basin, Argentina - Exploration model for a lowstand clastic wedge in a back-arc basin

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

Ryer, T.A.

1991-03-01

The Neuquen basin of western Argentina is a back-arc basin that was occupied by epeiric seas during much of Jurassic and Cretaceous time. The Avile Sandstone Member of the Agrio Formation records a pronounced but short-lived regression of the Agrio sea during middle Hauterivian (Early Cretaceous) time. Abrupt lowering of relative sea level resulted in emergence and erosion of the Agrio sea floor; shoreline and fluvial facies characteristic of the Centenario Formation shifted basinward. The Avile rests erosionally upon lower Agrio shale over a large area; well-sorted, porous sandstones within the member pinch out laterally against the base-Avile erosional surface.more » Avile deposition closed with an abrupt transgression of the shoreline to the approximate position it had occupied prior to the Avile regression. The transgressive deposits are carbonate rich, reflecting starvation of the basin as a consequence of sea-level rise. The Avile lowstand clastic wedge consists predominantly of sandstones deposited in fluvial to shallow-marine paleoenvironments; eolian sandstones probably constitute an important component in the eastern part of the area. The sandstones locally have excellent reservoir characteristics; they constitute the reservoirs in the Puesto Hernandez, Chihuido de la Sierra Negra, and Filo Morado fields. The pinch-out of the Avile lowstand clastic wedge has the potential to form stratigraphic traps in favorable structural positions. The depositional model indicates that there may be a viable stratigraphic play to be made along the Avile pinch-out in the deep, relatively undrilled, northwestern part of the Neuquen basin.« less

Depositional environments, sequence stratigraphy, and trap configuration of lower Wolfcampian clastics along eastern edge of Midland basin, west Texas

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

Stewart, N.R.; Reuter, S.G.

1989-03-01

The Lower Permian (lower Wolfcampian) along the eastern edge of the Midland basin, west Texas, is characterized by ramp-type shelf margins. During eustatic lowstand, nearshore sedimentation shifted drastically to the west into a basinal setting below the Pennsylvanian (Canyon) shelf margin. Core descriptions demonstrate that lowstand systems tract (LST) and transgressive systems tract (TST) siliciclastics were deposited in deltaic and coastal-plain environments. Prodelta, delta-front, and stream-mouth bar facies are associated with the LST. Coastal-plain and distributary channels are preserved in the TST. The sequence stratigraphic framework indicates type 1 sequence boundaries at 287 Ma, 282 Ma, and 280 Ma inmore » the lower Wolfcampian clastics. This lower Wolfcampian package of sedimentary rocks overlies the Pennsylvanian and is capped by the 279-Ma middle Wolfcampian unconformity. All three sequence boundaries and associated systems tract deposits exhibit a prograding stacking pattern within the sequence stratigraphic framework. Basinally restricted prograding LST deltaic rocks are overlain by backstepping TST deltaics and highstand systems tract (HST) outer marine shales. Production in lower Wolfcampian clastic fields is associated with fine-grained quartzarenites up to 45 ft thick which were deposited in stream-mouth bars. Delta-front and prodelta low-permeability shales encase the reservoir facies, forming lateral permeability barriers. HST outer marine shales deposited over the stream-mouth-bar sandstones act as a top seal, creating a stratigraphic trap and providing source for the high-BTU gas and oil produced from these basinally restricted LST deltaics.« less

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

USGS Publications Warehouse

Valentine, Page C.

1982-01-01

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.

Mesozoic units in SE Rhodope (Bulgaria): new structural and petrologic data and geodynamic implications for the Early Jurassic to Mid-Cretaceous evolution of the Vardar ocean basin

NASA Astrophysics Data System (ADS)

Bonev, N.; Stampfli, G.

2003-04-01

In the southeastern Rhodope, both in southern Bulgaria and northern Greece, Mesozoic low-grade to non-metamorphic units, together with similar units in the eastern Vardar zone, were designated as the Circum-Rhodope Belt (CRB) that fringes the Rhodope high-grade metamorphic complex. In the Bulgarian southeastern Rhodope, Mesozoic units show a complicated tectono-stratigraphy underlaid by amphibolite-facies basement units. The basement sequence includes a lower orthogneiss unit with eclogite and meta-ophiolite lenses overlain by an upper marble-schist unit, presumably along a SSW-directed detachment fault as indicated by shear sense indicators. The Mesozoic sequence starts with greenschist units at the base, overlaying the basement along the tectonic contact. Mineral assemblages such as actinolite-chlorite-white mica ± garnet in schists and phyllites indicate medium greenschist facies metamorphism. Kinematic indicators in the same unit demonstrate a top-to-the NNW and NNE shear deformation coeval with metamorphism, subparallel to NW-SE to NE-SW trending mineral elongation lineation and axis of NW vergent small-scale folds. The greenschist unit is overlain by tectonic or depositional contact of melange-like unit that consists of diabases with Lower Jurassic radiolarian chert interlayers, Upper Permian siliciclastics and Middle-Upper Triassic limestones found as blocks in olistostromic member, embedded in Jurassic-Lower Cretaceous turbiditic matrix. The uppermost sedimentary-volcanogenic unit is represented by andesito-basalt lavas and gabbro-diorites, interbedded with terrigeneous-marl and tufaceous sediments that yield Upper Cretaceous (Campanian) fossils, related to the Late Cretaceous back-arc magmatic activity to the north in Sredna Gora zone. Petrologic and geochemical data indicates sub-alkaline and tholeiitic character of the greenschists and ophiolitic basaltic lavas, and the latter are classified as low-K and very low-Ti basalts with some boninitic affinity. Immobile trace element discrimination of both rock types constrains the volcanic (oceanic)-arc origin. They generally show low total REE concentrations (LREE>HREE) with enrichment of LIL elements relative to the HFS elements, and also very low Nb and relatively high Ce content consistent with an island-arc tectonic setting. We consider that the Meliata-Maliac ocean northern passive margin could be the source provenance for the Upper Permian clastics and Middle-Upper Triassic limestone blocks within the olistostromic melange-like unit, whereas turbidites and magmatic blocks may originate in an island arc-accretionary complex that relates to the southward subduction of the Maliac ocean under the supra-subduction back-arc Vardar ocean/island arc system. These new structural and petrologic data allow to precise the tectonic setting of the Mesozoic units and their geodynamic context in the frame of the Early Jurassic to Late Cretaceous evolution of the Vardar ocean.

The Sedimentary History of Southern Central Crete: Implications for Neogene Uplift

NASA Astrophysics Data System (ADS)

Kröger, K.; Brachert, T. C.; Reuter, M.

2003-04-01

The tectonic setting of Crete was largely extensional since Lower Miocene uplift and exhumation of HP/LT rocks. Erosion of uplifted areas resulted in the deposition of terrestrial to marine sediments in the Messara and Iraclion Basins. There are several concurring models that discuss Late Neogene uplift of the basinal margins. Neogene near shore sediments in the south of the Messara Basin record fault movements contemporaneous to sedimentation and sedimentary input from the hinterland. Therefore they provide information on the paleogeographic situation and the resulting amount of subsidence and uplift of mountain areas since the Upper Miocene. The studied sediments consist of terrestrial to shallow marine, floodplain related sediments of the Upper Miocene Ambelouzos Formation that are overlain by platform limestones of the Upper Miocene Varvara Formation. In the Messara Basin these units are overlain by the Pliocene Kourtes Formation. The stratigraphic architecture of these deposits indicates fragmentation of the basinal margin. Proximal boulder conglomerates and reworked blocks of the Ambelouzos formation indicate fault activity during the deposition of the Varvara Formation. Contents of terrigenous clastics, provided by rivers and distributed by longshore currents, are high in the Ambelouzos and the lower Varvara Formations but decrease rapidly upsection within the Varvara Formation. This indicates drowning of the fault bounded blocks and little topography of the hinterland (Asteroussia Mountains) at that time. The Pliocene marls at the southern margin of the Messara Basin contain lithoclasts of the Upper Miocene limestones and thus indicate uplift of the carbonate platform. The modern topographic elevation of formerly drowned fault bounded blocks requires a minimum uplift of 400m. Main uplift occurred at approximately orthogonal NW-SE and SW-NE striking normal to oblique faults. The present elevation of the Asteroussia Mountains indicates net uplift of at least 1000m since the Early Pliocene. At the Central Iraklion Ridge that separates the Messara and Iraclion Basins a similar history is indicated for the Psiloritis Mountains by fault movements within Neogene near shore sediments and their subsequent drowning. A structural model of the Neogene evolution of Crete therefore has to explain successive phases of uplift and subsidence in an over all extensional setting only slightly oblique to the modern direction of convergence between Africa and the Aegean microplate.

Seismogenic rotational slumps and translational glides in pelagic deep-water carbonates. Upper Tithonian-Berriasian of Southern Tethyan margin (W Sicily, Italy)

NASA Astrophysics Data System (ADS)

Basilone, Luca

2017-07-01

Soft-sediment deformation structures (SSDSs), which reflect sediment mobilization processes, are helpful to identify punctual events of paleoenvironmental stresses. In the upper Tithonian-Berriasian calpionellid pelagic limestone of the Lattimusa Fm. outcropping in the Barracù section (W Sicily), paleoenvironmental restoration reveals the occurrence of a deep-water flat basin, characterised by undeformed planar bedding, laterally passing to a gentle slope where the deformed horizons alternate with undeformed beds. Here, two types of gravity slides have been differentiated on the basis of different kinds of SSDSs, brittle deformation, involved lithofacies, geometry and morphology. Type 1 slump sheets, involving marl-limestone couplets, are characterised by chaotic stratification, truncated beds, recumbent folds, tension gashes, clastic dikes and small-scale listric normal faults and thrusts. They moved downslope as a rotational slump, displaying the typical wedge-shaped morphology, becoming thicker toe-wards. Type 2 slump sheets, involving bed packages of lime mudstone, are characterised by arcuate slump scars developing downwards as listric normal faults, associated with rotational beds and bulging. Displaying tabular geometries, they moved coherently along an overall bedding parallel detachment surface as a translational glide characterised by sediment creep. Regional geology indicates that the basin (Sicanian), bordered by a stepped carbonate platform, was affected by synsedimentary tectonics throughout the Mesozoic. The synsedimentary extensional tectonics that affect the Upper Triassic-Jurassic deposits with steeped normal faults, causing tilt-block and instability of the seafloor through fluidization processes, triggered the rotational slumps of the lower portion of the section. Seismic shocks, induced by outside sector tectonics, like those recorded in the adjacent Busambra stepped carbonate platform margin, triggered the rotational slumps that are not related to local-scale faults. To explain the translational glides of the upper portion of the section, the aforementioned outside sector earthquakes produced instability of the sea-floor through thixotropy of marls. In this case, the driving forces (i.e., gravitational) were favoured by the uplifting trend that is well recorded in the Southern Tethyan continental margin. We suggest that the various early deformations represent rotational slump and sediment creep that may be characteristic for slump structures in pelagic carbonates, depending on the involved lithologies (i.e., paleoenvironmental setting) and the intensity/distance of the trigger mechanism (i.e., earthquake epicentre).

Facies development in the Lower Freeport coal bed, west-central Pennsylvania, U.S.A.

USGS Publications Warehouse

Pierce, B.S.; Stanton, R.W.; Eble, C.F.

1991-01-01

The Lower Freeport coal bed in west-central Pennsylvania is interpreted to have formed within a lacustrine-mire environment. Conditions of peat formation, caused by the changing chemical and physical environments, produced five coal facies and two mineral-rich parting facies within the coal bed. The coal bed facies are compositionally unique, having developed under varying conditions, and are manifested by megascopic, petrographic, palynologic and quality characteristics. The initial environment of the Lower Freeport peat resulted in a coal facies that is relatively high in ash yield and contains large amounts of lycopod miospores and moderate abundances of cryptotelinite, crypto-gelocollinite, inertinite and tree fern miospores. This initial Lower Freeport peat is interpreted to have been a topogenous body that was low lying, relatively nutrient rich (mesotrophic to eutrophic), and susceptible to ground water and to sediment influx from surface water. The next facies to form was a ubiquitous, clay-rich durain parting which is attributed to a general rise in the water table accompanied by widespread flooding. Following formation of the parting, peat accumulation resumed within an environment that inhibited clastic input. Development of doming in this facies restricted deposition of the upper shale parting to the margins of the mire and allowed low-ash peat to form in the interior of the mire. Because this environment was conducive to preservation of cellular tissue, this coal facies also contains large amounts of crypto-telinite. This facies development is interpreted to have been a transitional phase from topogenous, planar peat formation to slightly domed, oligotrophic (nutrient-poor) peat formation. As domed peat formation continued, fluctuations in the water table enabled oxidation of the peat surface and produced high inertinite concentrations toward the top of the coal bed. Tree ferns became an increasingly important peat contributor in the e upper facies, based on the palynoflora. This floral change is interpreted to have resulted from the peat surface becoming less wet or better drained, a condition that inhibited proliferation of lycopod trees. Accumulation of the peat continued until rising water levels formed a freshwater lake within which clays and silts were deposited. The development of the Lower Freeport peat from a planar mire through transitional phases toward domed peat formation may be an example of the type of peat formation of other upper Middle and Upper Pennsylvanian coal beds. ?? 1991.

Promise and Pitfalls of Using Grain Size Analysis to Identify Glacial Sediments in Alpine Lake Cores.

NASA Astrophysics Data System (ADS)

Clark, D. H.

2011-12-01

Lakes fed by glacier outwash should have a clastic particle-size record distinct from non-glacial lakes in the same area, but do they? The unique turquoise color of alpine glacial lakes reflects the flux of suspended clastic glacial rock flour to those lakes; conversely, lakes not fed by outwash are generally clear with sediments dominated by organics or slope-wash from nearby hillslopes. This contrast in sediment types and sources should produce a distinct and measureable different in grain sizes between the two settings. Results from a variety of lakes suggest the actual situation is often more subtle and complex. I compare grain size results to other proxies to assess the value of grain size analysis for paleoglacier studies. Over the past 10 years, my colleagues and I have collected and analyzed sediment cores from a wide variety of lakes below small alpine glaciers in an attempt to constrain the timing and magnitude of alpine glaciation in those basins. The basic concept is that these lakes act as continuous catchments for any rock flour produced upstream by glacier abrasion; as a glacier grows, the flux of rock flour to the lake will also increase. If the glacier disappears entirely, rock flour deposition will also cease in short order. We have focused our research in basins with simple sedimentologic settings: mostly small, high-altitude, stripped granitic or metamorphic cirques in which the cirque glaciers are the primary source of clastic sediments. In most cases, the lakes are fed by meltwater from a modern glacier, but were ice free during the earlier Holocene. In such cases, the lake cores should record formation of and changes in activity of the glacier upstream. We used a Malvern Mastersizer 2000 laser particle size analyzer for our grain size analyses, as well as recording magnetic susceptibility, color, and organics for the same cores. The results indicate that although lakes often experience increases in silt and clay-size (<0.63 mm) clastic particles when a glacier is present upstream, the signal can be highly variable and complex, most likely the result of stochastic processes in the basin. Our analyses indicate that although particle size reflects glacier activity upstream, it is rarely the best record of glacier change and is most useful in combination with other proxies, most notably MS, color, and organic content.

Falsifying the Sikussak-Oasis Hypothesis for the Tillite Group, East Greenland: Implications for Trezona-like Carbon Isotope Excursions Beneath Neoproterozoic Glacials

NASA Astrophysics Data System (ADS)

Hoffman, P. F.; Domack, E. W.; Maloof, A. C.; Halverson, G. P.

2006-05-01

In Neoproterozoic time, East Greenland and East Svalbard (EGES) occupied landward and seaward positions, respectively, on the southern subtropical margin of Laurentia. In both areas, thick clastic-to-carbonate successions are overlain by two discrete glacial and/or periglacial formations, separated by fine basinal clastics. In Svalbard, the younger glacial has a characteristic Marinoan (basal Ediacaran) cap dolostone, but the older glacial is underlain by a 10-permil negative carbon isotope excursion that is indistinguishable from excursions observed exclusively beneath Marinoan glacials in Australia, Namibia and western Laurentia. This led us to propose (Basin Research 16, 297-324, 2004) that the paired glacials in EGES represent the onset and climax of a single, long-lived, Marinoan glaciation. The intervening fine clastics, which contain ikaite pseudomorphs, presumptively accumulated beneath permanent shorefast sea ice (sikussak), analogous to East Greenland fjords during the Younger Dryas and Little Ice Age. In this model, the top of the older glacial signals the start of Snowball Earth. We conducted a preliminary field test of the sikussak hypothesis in Strindberg Land (SL), Andrée Land (AL) and Ella O (EO), East Greenland. We confirmed the correlation of the paired glacials and the Marinoan cap dolostone (missing on EO). In SL, the older glacial (Ulveso Fm) is a thin diamictite overlain by conglomerate lag and a set of megavarves composed of alternating siltstone and ice-rafted debris. In AL and EO, the Ulveso is a sub-glacial diamictite overlain by aeolian and/or marine sandstone. In Bastion Bugt on EO, it is a transgressive shoreface sandstone. This proves that glacial recession occurred under open-water conditions and did not result from permanent sea-ice formation, as stipulated in the sikussak model. There is no evidence that the fine clastic sequence between the glacials formed under an ice cover, or for a single glacial period. This brings us back to the original problem: either the younger glacial is post-Marinoan, or the older one is Sturtian. We think the first possibility is unlikely because the cap strata compare in detail with Marinoan equivalents in Canada. If the older glacial is Sturtian, then large negative carbon isotope excursions directly preceded two successive "snowball earth" episodes.

Effect of faults on fluid flow and chloride contamination in a carbonate aquifer system

USGS Publications Warehouse

Maslia, M.L.; Prowell, D.C.

1990-01-01

A unified, multidiscipline hypothesis is proposed to explain the anomalous pattern by which chloride has been found in water of the Upper Floridan aquifer in Brunswick, Glynn County, Georgia. Analyses of geophysical, hydraulic, water chemistry, and aquifer test data using the equivalent porous medium (EPM) approach are used to support the hypothesis and to improve further the understanding of the fracture-flow system in this area. Using the data presented herein we show that: (1) four major northeast-southwest trending faults, capable of affecting the flow system of the Upper Floridan aquifer, can be inferred from structural analysis of geophysical data and from regional fault patterns; (2) the proposed faults account for the anomalous northeastward elongation of the potentiometric surface of the Upper Floridan aquifer; (3) the faults breach the nearly impermeable units that confine the Upper Floridan aquifer from below, allowing substantial quantities of water to leak vertically upward; as a result, aquifer transmissivity need not be excessively large (as previously reported) to sustain the heavy, long-term pumpage at Brunswick without developing a steep cone of depression in the potentiometric surface; (4) increased fracturing at the intersection of the faults enhances the development of conduits that allow the upward migration of high-chloride water in response to pumping from the Upper Floridan aquifer; and (5) the anomalous movement of the chloride plume is almost entirely controlled by the faults. ?? 1990.

The Messinian evaporites in the Levant Basin: lithology, deformation and its evolution

NASA Astrophysics Data System (ADS)

Feng, Ye; Steinberg, Josh; Reshef, Moshe

2017-04-01

The lithological composition of the Messinian evaporite in the Levant Basin remains controversial and salt deformation mechanisms are still not fully understood, due to the lack of high resolution 3D depth seismic data and well logs that record the entire evaporite sequence. We demonstrate how 3D Pre-stack depth migration (PSDM) and intra-salt tomography can lead to improved salt imaging. Using 3D PSDM seismic data with great coverage and deepwater well log data from recently drilled boreholes, we reveal intra-salt reflective units associated with thin clastic layers and a seismic transparent background consisting of uniform pure halite. Structural maps of all internal reflectors are generated for stratigraphy and attributes analysis. High amplitude fan structures in the lowermost intra-salt reflector are observed, which may indicate the source of the clastic formation during the Messinian Salinity Crisis (MSC). The Messinian evaporite in the Levant Basin comprises six units; the uppermost unit thickens towards the northwest, whereas the other units are uniform in thickness. The top of salt (TS) horizon is relatively horizontal, while all other intra-salt reflectors and base of salt (BS) dip towards the northwest. Different seismic attributes are used for identification of intra-salt deformation patterns. Maximum curvature maps show NW-striking thrust faults on the TS and upper intra-salt units, and dip azimuth maps are used to show different fold orientations between the TS and intra-salt units, which indicate a two-phase deformation mechanism: basin NW tilting as syn-depositional phase and NNE spreading of Plio-Pleistocene overburden as post-depositional phase. RMS amplitude maps are used to identify a channelized system on the TS. An evaporite evolution model during the MSC of the Levant Basin is therefore established based on all the observations. Finally the mechanical properties of the salts will be utilized to explore salt deformation in the Levant Basin. Feng, Y. E., & Reshef, M. (2016). The Eastern Mediterranean Messinian salt-depth imaging and velocity analysis considerations. Petroleum Geoscience, 22(4), 2-19. doi:http://dx.doi.org/10.1144/petgeo2015-088 Feng, Y. E., Yankelzon, A., Steinberg, J., & Reshef, M. (2016). Lithology and characteristics of the Messinian evaporite sequence of the deep Levant Basin, eastern Mediterranean. Marine Geology, 376, 118-131. doi:http://dx.doi.org/10.1016/j.margeo.2016.04.004

Petrography, geochemistry, and depositional setting of the San Pedro and Santo Tomas coal zones: Anomalous algae-rich coals in the middle part of the Claiborne Group (Eocene) of Webb County, Texas

USGS Publications Warehouse

Warwick, Peter D.; Hook, Robert W.

1995-01-01

Two coal zones, the San Pedro and the overlying Santo Tomas, are present for nearly 35 km in outcrop, surface and underground mines, and shallow drill holes along the strike of the middle part of the Claiborne Group (Eocene) in Webb County, Texas. A sandstone-dominated interval of 25 to 35 m separates the two coal zones, which range up to 3 m in thickness. Each coal zone contains carbonaceous shales, thin (<0.75 m) impure coal beds, and thin (<0.85 m) but commercially significant nonbanded coal beds. The nonbanded coals are different from other Tertiary coals of the Gulf of Mexico Coastal Plain: unlike lignites that are typical of the older Wilcox Group (Paleocene-Eocene) and younger Jackson Group (Eocene), nonbanded coals of the Claiborne Group have high vitrinite-reflectance values (0.53 Rmax) and high calorific yields (average 6670 kcal/kg or 12,000 Btu, dry basis). The coals are weakly agglomerating (free-swelling index is 1.5–2.0) and have an apparent rank of high-volatile bituminous.The coal-bearing portion of the middle Claiborne Group in the Rio Grande area represents a fining-upward transition from sandstone-dominated, marine-influenced, lower delta plain depositional environments to more inland, mudstone-rich, predominantly freshwater deltaic settings. Discontinuities within the San Pedro coal zone are attributed mainly to the influence of contemporaneous deposition of distributary mouth-bar sand bodies. The less variable nature of the Santo Tomas coal zone reflects its origin in the upper part of an interlobe basin that received only minor clastic influx.Petrographic attributes of the nonbanded coals indicate that they formed subaqueously in fresh to possibly brackish waters. A highly degraded groundmass composed of eugelinite is the main petrographic component (approximately 71%, mineral-matter-free basis). An enriched liptinite fraction (approximately 23%) probably accounts for unusually high calorific values. There is negligible inertinite. Petrographic study of polished blocks indicates that approximately 10 percent of the nonbanded coal from both coal zones is composed of green algae fructifications, which also occur in clastic rocks of the coal-bearing interval. Such algal material cannot be identified or quantified by conventional coal petrographic techniques that utilize particle pellets or by palynological analyses that include acid preparation.

Tectonics of Antarctica

USGS Publications Warehouse

Hamilton, W.

1967-01-01

Antarctica consists of large and wholly continental east Antarctica and smaller west Antarctica which would form large and small islands, even after isostatic rebound, if its ice cap were melted. Most of east Antarctica is a Precambrian Shield, in much of which charnockites are characteristic. The high Transantarctic Mountains, along the Ross and Weddell Seas, largely follow a geosyncline of Upper Precambrian sedimentary rocks that were deformed, metamorphosed and intruded by granitic rocks during Late Cambrian or Early Ordovician time. The rocks of the orogen were peneplained, then covered by thin and mostly continental Devonian-Jurassic sediments, which were intruded by Jurassic diabase sheets and overlain by plateau-forming tholeiites. Late Cenozoic doming and block-faulting have raised the present high mountains. Northeastern Victoria Land, the end of the Transantarctic Mountains south of New Zealand, preserves part of a Middle Paleozoic orogen. Clastic strata laid unconformably upon the Lower Paleozoic plutonic complex were metamorphosed at low grade, highly deformed and intruded by Late Devonian or Early Carboniferous granodiorites. The overlying Triassic continental sedimentary rocks have been broadly folded and normal-faulted. Interior west Antarctica is composed of miogeosynclinal clastic and subordinate carbonate rocks which span the Paleozoic Era and which were deformed, metamorphosed at generally low grade, and intruded by granitic rocks during Early Mesozoic time and possibly during other times also. Patterns of orogenic belts, if systematic, cannot yet be defined; but fragmentation and rotation of crustal blocks by oroclinal folding and strike-slip faulting can be suggested. The Ellsworth Mountains, for example, consist of Cambrian-Permian metasedimentary rocks that strike northward toward the noncorrelative and latitudinally striking Mesozoic terrane of the Antarctic Peninsula in one direction and southward toward that of the Lower Paleozoic: terrane of the Transantarctic Mountains in the other; the three regions may be separated by great strike-slip faults. The Antarctic Peninsula in west Antarctica, south of South America, consists of metavolcanic and metasedimentary rocks intruded by Late Cretaceous quartz diorite. The pre-granitic rocks are of Jurassic and Early Cretaceous ages wherever they have been dated by fossils, although some crystalline complexes may be older. The S-shape of the peninsula may represent oroclinal bending within Cenozoic time as part of a motion system in which a narrow continental bridge between South America and Antarctica was deformed and ruptured. Perhaps this bridge lagged behind as the larger continental plates drifted into the Pacific Ocean Basin. ?? 1967.

What can the dihedral angle of conjugate-faults tell us?

NASA Astrophysics Data System (ADS)

Ismat, Zeshan

2015-04-01

Deformation within the upper crust (elastico-frictional regime) is largely accommodated by fractures and conjugate faults. The Coulomb fracture criterion leads us to expect that the average dihedral angle of conjugate-fault sets is expected to be ∼60°. Experiments, however, reveal a significant amount of scatter from this 60° average. The confining pressure under which these rocks are deformed is a contributing factor to this scatter. The Canyon Range syncline, Sevier fold-thrust belt (USA) and the Jebel Bani, Anti-Atlas fold-belt (Morocco) both folded under different depths, within the elastico-frictional regime, by cataclastic flow. Conjugate-fault sets assisted deformation by cataclastic flow. The Canyon Range syncline and the Jebel Bani are used here as natural examples to test the relationship between the dihedral angle of conjugate-faults and confining pressure. Variations is confining pressure are modeled by the difference in depth of deformation and position within the folds. Results from this study show that the dihedral angle increases with an increase in depth and within the hinge regions of folds, where space problems commonly occur. Moreover, the shortening directions based on the acute bisectors of conjugate-faults may not be accurately determined if the dihedral angles are unusually large or small, leading to incorrect kinematic analyses.

Observation of superconducting vortex clusters in S/F hybrids

DOE PAGES

Di Giorgio, C.; Bobba, F.; Cucolo, A. M.; ...

2016-12-09

While Abrikosov vortices repel each other and form a uniform vortex lattice in bulk type-II superconductors, strong confinement potential profoundly affects their spatial distribution eventually leading to vortex cluster formation. The confinement could be induced by the geometric boundaries in mesoscopic-size superconductors or by the spatial modulation of the magnetic field in superconductor/ ferromagnet (S/F) hybrids. Here we study the vortex confinement in S/F thin film heterostructures and we observe that vortex clusters appear near magnetization inhomogeneities in the ferromagnet, called bifurcations. We use magnetic force microscopy to image magnetic bifurcations and superconducting vortices, while high resolution scanning tunneling microscopymore » is used to obtain detailed information of the local electronic density of states outside and inside the vortex cluster. We find an intervortex spacing at the bifurcation shorter than the one predicted for the same superconductor in a uniform magnetic field equal to the thermodynamical upper critical field H c2. This result is due to a local enhanced stray field and a competition between vortex-vortex repulsion and Lorentz force. Here, our findings suggest that special magnetic topologies could result in S/F hybrids that support superconductivity even when locally the vortex density exceeds the thermodynamic critical threshold value beyond which the superconductivity is destroyed.« less

Mini-filament Eruptions Triggering Confined Solar Flares Observed by ONSET and SDO

NASA Astrophysics Data System (ADS)

Yang, Shuhong; Zhang, Jun

2018-06-01

Using the observations from the Optical and Near-infrared Solar Eruption Tracer (ONSET) and the Solar Dynamics Observatory (SDO), we study an M5.7 flare in AR 11476 on 2012 May 10 and a micro-flare in the quiet Sun on 2017 March 23. Before the onset of each flare, there is a reverse S-shaped filament above the polarity inversion line, then the filaments become unstable and begin to rise. The rising filaments gain the upper hand over the tension force of the dome-like overlying loops and thus successfully erupt outward. The footpoints of the reconnecting overlying loops successively brighten and are observed as two flare ribbons, while the newly formed low-lying loops appear as post-flare loops. These eruptions are similar to the classical model of successful filament eruptions associated with coronal mass ejections (CMEs). However, the erupting filaments in this study move along large-scale lines and eventually reach the remote solar surface; i.e., no filament material is ejected into the interplanetary space. Thus, both the flares are confined. These results reveal that some successful filament eruptions can trigger confined flares. Our observations also imply that this kind of filament eruption may be ubiquitous on the Sun, from active regions (ARs) with large flares to the quiet Sun with micro-flares.

Observation of superconducting vortex clusters in S/F hybrids.

PubMed

Di Giorgio, C; Bobba, F; Cucolo, A M; Scarfato, A; Moore, S A; Karapetrov, G; D'Agostino, D; Novosad, V; Yefremenko, V; Iavarone, M

2016-12-09

While Abrikosov vortices repel each other and form a uniform vortex lattice in bulk type-II superconductors, strong confinement potential profoundly affects their spatial distribution eventually leading to vortex cluster formation. The confinement could be induced by the geometric boundaries in mesoscopic-size superconductors or by the spatial modulation of the magnetic field in superconductor/ferromagnet (S/F) hybrids. Here we study the vortex confinement in S/F thin film heterostructures and we observe that vortex clusters appear near magnetization inhomogeneities in the ferromagnet, called bifurcations. We use magnetic force microscopy to image magnetic bifurcations and superconducting vortices, while high resolution scanning tunneling microscopy is used to obtain detailed information of the local electronic density of states outside and inside the vortex cluster. We find an intervortex spacing at the bifurcation shorter than the one predicted for the same superconductor in a uniform magnetic field equal to the thermodynamical upper critical field H c2 . This result is due to a local enhanced stray field and a competition between vortex-vortex repulsion and Lorentz force. Our findings suggest that special magnetic topologies could result in S/F hybrids that support superconductivity even when locally the vortex density exceeds the thermodynamic critical threshold value beyond which the superconductivity is destroyed.

Observation of superconducting vortex clusters in S/F hybrids

PubMed Central

Di Giorgio, C.; Bobba, F.; Cucolo, A. M.; Scarfato, A.; Moore, S. A.; Karapetrov, G.; D’Agostino, D.; Novosad, V.; Yefremenko, V.; Iavarone, M.

2016-01-01

While Abrikosov vortices repel each other and form a uniform vortex lattice in bulk type-II superconductors, strong confinement potential profoundly affects their spatial distribution eventually leading to vortex cluster formation. The confinement could be induced by the geometric boundaries in mesoscopic-size superconductors or by the spatial modulation of the magnetic field in superconductor/ferromagnet (S/F) hybrids. Here we study the vortex confinement in S/F thin film heterostructures and we observe that vortex clusters appear near magnetization inhomogeneities in the ferromagnet, called bifurcations. We use magnetic force microscopy to image magnetic bifurcations and superconducting vortices, while high resolution scanning tunneling microscopy is used to obtain detailed information of the local electronic density of states outside and inside the vortex cluster. We find an intervortex spacing at the bifurcation shorter than the one predicted for the same superconductor in a uniform magnetic field equal to the thermodynamical upper critical field Hc2. This result is due to a local enhanced stray field and a competition between vortex-vortex repulsion and Lorentz force. Our findings suggest that special magnetic topologies could result in S/F hybrids that support superconductivity even when locally the vortex density exceeds the thermodynamic critical threshold value beyond which the superconductivity is destroyed. PMID:27934898

Simulation of ground-water flow and movement of the freshwater-saltwater interface in the New Jersey coastal plain

USGS Publications Warehouse

Pope, Daryll A.; Gordon, Alison D.

1999-01-01

The confined aquifers of the New Jersey Coastal Plain are sands that range in thickness from 50 to 600 feet and are separated by confining units. The confining units are composed of silts and clays that range in thickness from 500 to 1,000 feet. The aquifers are recharged by precipitation on their outcrop areas. This water then flows laterally downdip and vertically to the deeper confined aquifers. The confined aquifers ultimately discharge to the Raritan and Delaware Bays and to the Atlantic Ocean. In 1988, ground-water withdrawals from confined and unconfined New Jersey Coastal Plain aquifers were approximately 345 million gallons per day, more than 75 percent of which was pumped from the confined aquifers. These withdrawals have created large cones of depression in several Coastal Plain aquifers near populated areas, particularly in Camden and Monmouth Counties. The continued decline of water levels in confined aquifers can cause saltwater intrusion, reduce stream discharge near the outcrop areas, and threaten the quality of the ground-water supply. SHARP, a quasi-three-dimensional finite-difference computer model that can simulate freshwater and saltwater flow, was used to simulate the ground-water flow system in the New Jersey Coastal Plain, including the location and movement of the freshwater-saltwater interface in nine aquifers and eight intervening confining units. The freshwater-saltwater interface is defined as the hypothetical line seaward of which the chloride concentration is equal to or greater than 10,000 milligrams per liter. Model simulations were used to estimate the location and movement of the freshwater-saltwater interface resulting from (1) eustatic sea-level changes over the past 84,000 years, (2) ground-water withdrawals from 1896 through 1988, (3) and future ground-water withdrawals from 1988 to 2040 from Coastal Plain aquifers. Simultion results showed that the location and movement of the freshwater-saltwater interface are more dependent on the historical sea level than on the stresses imposed on the flow system by ground-water withdrawals from the Coastal Plain aquifers from 1896 to 1988. Results of a predictive simulation in which pumpage from existing wells was increased by 30 percent indicate that additional withdrawals from each of the eight confined aquifers in the Coastal Plain would broaden and deepen the existing cones of depression and result in significant drawdowns from the 1988 potentiometric surfaces. Drawdowns of 30 feet were simulated at the center of the cone of depression in the Upper, Middle, and Lower Potomac-Raritan-Magothy aquifers in Camden and Ocean Counties. Simulated drawdowns exceeded 80 feet at the center of the cone of depression in the Wenonah-Mount Laurel and Englishtown aquifers in Monmouth County. Drawdowns of 30 feet were simulated in the lower Kirkwood-Cohansey and confined Kirkwood aquifers in Cape May County. Simulation results showed that the increase in ground-water withdrawals would result in only minimal movement of the freshwater-saltwater interface by 2040, despite large drawdowns.

Recent Developments in Facies Models for Siliciclastic Sediments.

ERIC Educational Resources Information Center

Miall, Andrew D.

1982-01-01

Discusses theory of facies models (attempts to synthesize/generalize information about depositional environments), strengths/weaknesses of facies modelling, recent advances in facies models for siliciclastic sediments (focusing on fluvial, lacustrine, eolian and glacial environments, clastic shorelines and continental shelves, and clastic…

Quasi-Decadal Oscillations Generated by the QBO

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Mengel, J. G.; Drob, D. P.; Porter, H. S.; Chan, K. L.; Bhartia, P. K. (Technical Monitor)

2001-01-01

Quasi-decadal oscillations (QDO) have been observed in the stratosphere and have been linked to the equatorial Quasi-Biennial Oscillation (QBO) and to the 11-year solar activity cycle. With the use of a 2D version of our Numerical Spectral Model (NSM) that incorporates Hines' Doppler Spread Parameterization (DSP) for gravity waves (GW), we demonstrate that beat periods between 9 and 11 years can be generated by the QBO as it interacts through GW filtering with the Annual Oscillation (AO) and Semi-annual Oscillation (SAO). Results are discussed from computations covering up to 50 years, and our analyses leads to the following conclusions. The QDO as a stand-alone signature is largely confined to the upper mesosphere. Its largest signature appears in the form of amplitude modulations of the QBO, AO and SAO, and these extend into the lower stratosphere. The downward control that characterizes the QBO apparently comes into play, and the longer time constants for diffusion and radiative loss at lower altitudes facilitate the QDO response. Although excited by the QBO, which is confined to low latitudes, the QDO is shown to extend to high latitudes. The effect is particularly large for the QBO with period around 33.5 month (near the upper limit of observations), which interacts with the SAO to produce a hemispherically symmetric QDO. Our analysis indicates that the QDO is transferred to high latitudes by the meridional circulation, which prominently exhibits this periodicity particularly in the amplitude modulation of the AO.

Hydrogeology of a hazardous-waste disposal site near Brentwood, Williamson County, Tennessee

USGS Publications Warehouse

Tucci, Patrick; Hanchar, D.W.; Lee, R.W.

1990-01-01

Approximately 44,000 gal of industrial solvent wastes were disposed in pits on a farm near Brentwood, Tennessee, in 1978, and contaminants were reported in the soil and shallow groundwater on the site in 1985. In order for the State to evaluate possible remedial-action alternatives, an 18-month study was conducted to define the hydrogeologic setting of the site and surrounding area. The area is underlain by four hydrogeologic units: (1) an upper aquifer consisting of saturated regolith, Bigby-Cannon Limestone, and weathered Hermitage Formation; (2) the Hermitage confining unit; (3) a lower aquifer consisting of the Carters Limestone; and (4) the Lebanon confining unit. Wells generally are low yielding less than 1 gal/min ), although locally the aquifers may yield as much as 80 gal/minute. This lower aquifer is anisotropic, and transmissivity of this aquifer is greatest in a northwest-southeast direction. Recharge to the groundwater system is primarily from precipitation, and estimates of average annual recharge rates range from 6 to 15 inches/year. Discharge from the groundwater system is primarily to the Little Harpeth River and its tributaries. Groundwater flow at the disposal site is mainly to a small topographic depression that drains the site. Geochemical data indicate four distinct water types. These types represent (1) shallow, rapidly circulating groundwater; (2) deeper (> than 100 ft), rapidly circulating groundwater; (3) shallow, slow moving groundwater; and (4) deeper, slow moving groundwater. Results of the numerical model indicate that most flow is in the upper aquifer. (USGS)

Flowmetering of drainage wells in Kuwait City, Kuwait

USGS Publications Warehouse

Paillet, Frederick L.; Senay, Y.; Mukhopadhyay, A.; Szekely, F.

2000-01-01

A heat-pulse flowmeter was used in six drainage wells in Kuwait City for flow profiling under both ambient and pumping conditions. The data collected were used in: (a) estimating the cross-flow among the screened intervals under ambient conditions; (b) estimating the relative transmissivity adjacent to the individual screen zones; and (c) determination of the hydraulic heads at the far boundaries of the large-scale aquifer zones. These inferences were cross-checked against known hydrogeology of the aquifer-aquitard system in the study area, and the calibration results of numerical flow modeling. The major conclusions derived from the flow measurements were: (a) the presence of natural downward cross-flow under ambient condition supported the hypothesis that the upper part of the Kuwait Group aquifer in the study area was divided into a series of permeable units (aquifers), separated by confining or semi-confining beds (aquitards); (b) the head differences between the different screened zones, derived through modeling of the flowmeter data of the wells, provided additional confirmation for the division of the upper part of the Kuwait Group aquifer into compartments in the study area; (c) flowmeter data indicated that the second and third aquifers were contributing most of the water to the well bores, compared with the uppermost (first) and the lowermost (fourth) aquifers; and (d) inflow to the wells during pumping was associated with discrete sub-intervals in the screened zones, controlled by local aquifer heterogeneity, and possibly clogging of screens and gravel pack.

The Sunny Point Formation: a new Upper Cretaceous subsurface unit in the Carolina Coastal Plain

USGS Publications Warehouse

Balson, Audra E.; Self-Trail, Jean; Terry, Dennis O.

2013-01-01

This paper formally defines the Sunny Point Formation, a new Upper Cretaceous subsurface unit confined to the outer Atlantic Coastal Plain of North and South Carolina. Its type section is established in corehole NH-C-1-2001 (Kure Beach) from New Hanover County, North Carolina. The Sunny Point Formation consists of light-olive-gray to greenish-gray, fine to coarse micaceous sands and light-olive-brown and grayish-red silty, sandy clays. The clay-rich sections typically include ironstone, lignitized wood, root traces, hematite concretions, goethite, limonite, and sphaerosiderites. The Sunny Point Formation is also documented in cores from Bladen County, North Carolina, and from Dorchester and Horry Counties, South Carolina. Previously, strata of the Sunny Point Formation had been incorrectly assigned to the Cape Fear and Middendorf Formations. The Sunny Point occupies a stratigraphic position above the Cenomanian marine Clubhouse Formation and below an upper Turonian unnamed marine unit. Contacts between these units are sharp and unconformable. Calcareous nannofossil and palynomorph analyses indicate that the Sunny Point Formation is Turonian.

Acquired bilateral telangiectatic macules: a distinct clinical entity.

PubMed

Park, Ji-Hye; Lee, Dong Jun; Lee, Yoo-Jung; Jang, Yong Hyun; Kang, Hee Young; Kim, You Chan

2014-09-01

We evaluated 13 distinct patients with multiple telangiectatic pigmented macules confined mostly to the upper arms to determine if the clinical and histopathological features of these cases might represent a specific clinical entity. We retrospectively investigated the clinical, histopathologic, and immunohistochemical features of 13 patients with multiple telangiectatic pigmented macules on the upper arms who presented between January 2003 and December 2012. Epidermal pigmentation, melanogenic activity, melanocyte number, vascularity, epidermal thickness, and perivascular mast cell number of the specimens were evaluated. Clinically, the condition favored middle-aged men. On histopathologic examination, the lesional skin showed capillary proliferation and telangiectasia in the upper dermis. Histochemical and immunohistochemical analysis revealed basal hyperpigmentation and increased melanogenic activity in the lesional skin (P < .05). No significant difference in epidermal thickness or mast cell number was observed between the normal perilesional skin and the lesional skin. The clinical and histopathologic features of these lesions were relatively consistent in all patients. In addition, the features are quite distinct from other diseases. Based on clinical and histologic features, we suggest the name acquired bilateral telangiectatic macules for this new entity.

Designing global climate and atmospheric chemistry simulations for 1 and 10 km diameter asteroid impacts using the properties of ejecta from the K-Pg impact

NASA Astrophysics Data System (ADS)

Toon, Owen B.; Bardeen, Charles; Garcia, Rolando

2016-10-01

About 66 million years ago, an asteroid about 10 km in diameter struck the Yucatan Peninsula creating the Chicxulub crater. The crater has been dated and found to be coincident with the Cretaceous-Paleogene (K-Pg) mass extinction event, one of six great mass extinctions in the last 600 million years. This event precipitated one of the largest episodes of rapid climate change in Earth's history, yet no modern three-dimensional climate calculations have simulated the event. Similarly, while there is an ongoing effort to detect asteroids that might hit Earth and to develop methods to stop them, there have been no modern calculations of the sizes of asteroids whose impacts on land would cause devastating effects on Earth. Here, we provide the information needed to initialize such calculations for the K-Pg impactor and for a 1 km diameter impactor. There is considerable controversy about the details of the events that followed the Chicxulub impact. We proceed through the data record in the order of confidence that a climatically important material was present in the atmosphere. The climatic importance is roughly proportional to the optical depth of the material. Spherules with diameters of several hundred microns are found globally in an abundance that would have produced an atmospheric layer with an optical depth around 20, yet their large sizes would only allow them to stay airborne for a few days. They were likely important for triggering global wildfires. Soot, probably from global or near-global wildfires, is found globally in an abundance that would have produced an optical depth near 100, which would effectively prevent sunlight from reaching the surface. Nanometer-sized iron particles are also present globally. Theory suggests these particles might be remnants of the vaporized asteroid and target that initially remained as vapor rather than condensing on the hundred-micron spherules when they entered the atmosphere. If present in the greatest abundance allowed by theory, their optical depth would have exceeded 1000. Clastics may be present globally, but only the quartz fraction can be quantified since shock features can identify it. However, it is very difficult to determine the total abundance of clastics. We reconcile previous widely disparate estimates and suggest the clastics may have had an optical depth near 100. Sulfur is predicted to originate about equally from the impactor and from the Yucatan surface materials. By mass, sulfur is less than 10 % of the observed mass of the spheres and estimated mass of nanoparticles. Since the sulfur probably reacted on the surfaces of the soot, nanoparticles, clastics, and spheres, it is likely a minor component of the climate forcing; however, detailed studies of the conversion of sulfur gases to particles are needed to determine if sulfuric acid aerosols dominated in late stages of the evolution of the atmospheric debris. Numerous gases, including CO2, SO2 (or SO3), H2O, CO2, Cl, Br, and I, were likely injected into the upper atmosphere by the impact or the immediate effects of the impact such as fires across the planet. Their abundance might have increased relative to current ambient values by a significant fraction for CO2, and by factors of 100 to 1000 for the other gases. For the 1 km impactor, nanoparticles might have had an optical depth of 1.5 if the impact occurred on land. If the impactor struck a densely forested region, soot from the forest fires might have had an optical depth of 0.1. Only S and I would be expected to be perturbed significantly relative to ambient gas-phase values. One kilometer asteroids impacting the ocean may inject seawater into the stratosphere as well as halogens that are dissolved in the seawater. For each of the materials mentioned, we provide initial abundances and injection altitudes. For particles, we suggest initial size distributions and optical constants. We also suggest new observations that could be made to narrow the uncertainties about the particles and gases generated by large impacts.

Hydrology, Water Quality, and Surface- and Ground-Water Interactions in the Upper Hillsborough River Watershed, West-Central Florida

USGS Publications Warehouse

Trommer, J.T.; Sacks, L.A.; Kuniansky, E.L.

2007-01-01

A study of the Hillsborough River watershed was conducted between October 1999 through September 2003 to characterize the hydrology, water quality, and interaction between the surface and ground water in the highly karstic uppermost part of the watershed. Information such as locations of ground-water recharge and discharge, depth of the flow system interacting with the stream, and water quality in the watershed can aid in prudent water-management decisions. The upper Hillsborough River watershed covers a 220-square-mile area upstream from Hillsborough River State Park where the watershed is relatively undeveloped. The watershed contains a second order magnitude spring, many karst features, poorly drained swamps, marshes, upland flatwoods, and ridge areas. The upper Hillsborough River watershed is subdivided into two major subbasins, namely, the upper Hillsborough River subbasin, and the Blackwater Creek subbasin. The Blackwater Creek subbasin includes the Itchepackesassa Creek subbasin, which in turn includes the East Canal subbasin. The upper Hillsborough River watershed is underlain by thick sequences of carbonate rock that are covered by thin surficial deposits of unconsolidated sand and sandy clay. The clay layer is breached in many places because of the karst nature of the underlying limestone, and the highly variable degree of confinement between the Upper Floridan and surficial aquifers throughout the watershed. Potentiometric-surface maps indicate good hydraulic connection between the Upper Floridan aquifer and the Hillsborough River, and a poorer connection with Blackwater and Itchepackesassa Creeks. Similar water level elevations and fluctuations in the Upper Floridan and surficial aquifers at paired wells also indicate good hydraulic connection. Calcium was the dominant ion in ground water from all wells sampled in the watershed. Nitrate concentrations were near or below the detection limit in all except two wells that may have been affected by fertilizer or animal waste. Wells at the Blackwater Creek and Hillsborough River at State Road 39 transects showed little seasonal variation in dissolved organic carbon. Dissolved organic carbon concentrations, however, were greater during the wet season than during the dry season at the Hillsborough River Tract transect, indicating some influence from surface-water sources. During dry periods, streamflow in the upper Hillsborough River was sustained by ground water from the underlying Upper Floridan aquifer. During wet periods, streamflow had additional contributions from runoff, and release of water from extensive riverine wetlands, and by overflow from the Withlacoochee River. In contrast, streamflow in Blackwater and Itchepackesassa Creeks was less constant, with many no-flow days occurring during dry periods. During wet season storm events, streamflow peaks occur more rapidly because there is greater confinement between the surficial deposits and the Upper Floridan aquifer, and these creeks have been highly channelized, leaving less of the adjacent wetlands intact. During dry periods, Blackwater Creek is dry upstream from its confluence with Itchepackesassa Creek, and all downstream flow is from Itchepackesassa Creek. Much of the dry season flow in Itchepackesassa Creek originates from a treated wastewater effluent outfall located on East Canal. Long-term streamflow at the Hillsborough River and Blackwater Creek stations was greater than the discharge observed during the study period. Water quality in the upper Hillsborough River is influenced by ground-water discharge. The chemical composition of water from Blackwater Creek, Itchepackesassa Creek, and East Canal was more variable because there was less ground-water discharge to these creeks than to the upper Hillsborough River, and because of the influence of wastewater effluent. Strontium isotope data indicated that the source of the water at all Hillsborough River sites during the dry season was the Oli