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At least 1,243 records · Page 69Linked to original sources
USGS1975

Radiometric age map of northern Alaska

This map includes published, thesis, and open-file radiometric data available to us as of June, 1975. Some dates are not plotted because of inadequate location data in the original references. The map is divided into five sections, based on 1:1,000,000 scale enlargements of the National Atlas maps of Alaska. Within each section (e.g., southeastern Alaska), radiometric dates are plotted and keyed to 1:250,000 scale quadrangles. Accompanying each map section is table 1, listing map numbers and the sample identification numbers used in DGGS Special Report 10: Radiometric Dates from Alaska-A 1975 Compilation”. The reader is referred to Special Report 10 for more complete information on location, rock type, dating method, and literature references for each age entry. A listing of dates in Special Report lo which require correction or deletion is included S table 2. Corrected and additional entries are listed in table 3. The listings in tables 2 and 3 follow the format of Special Report 10. Table 4 is a glossary of abbreviations used for quadrangle name, rock type, mineral dated, and type of dating method used.

Alaska↗
USGS2007

Magnetotelluric Data, Mid Valley, Nevada Test Site, Nevada

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.

Open-File Report↗
USGS1992

Jurassic ash-flow sheets, calderas, and related intrusions of the Cordilleran volcanic arc in southeastern Arizona: Implications for regional tectonics and ore deposits

Volcanologic, petrologic, and paleomagnetic studies of widespread Jurassic ash-flow sheets in the Huachuca-southern Dragoon Mountains area have led to identification of four large source calderas and associated comagmatic intracaldera intrusions. Stratigraphic, facies, and contact features of the caldera-related tuffs also provide constraints on the locations, lateral displacements, and very existence for some major northwest-trending faults and inferred regional thrusts in south-eastern Arizona. For example, the intricate Cochise thrust system, as mapped by others in the southern Dragoon Mountains, consists instead of primary depositional contacts within caldera-fill megabreccia, and the inferred regional thrusts do not exist, at least as previously interpreted. Silicic alkalic compositions of the Jurassic caldera-related, ash-flow tuffs; bimodal associated mafic magmatism; and interstratified coarse sedimentary deposits provide evidence for synvolcanic extension and rifting within the Cordilleran magmatic arc. Gold-copper mineralization is associated with subvolcanic intrusions at several of the Jurassic calderas.

Arizona↗
USGS1975

Silurian and Devonian miogeosynclinal and transitional rocks of the Fish Creek Reservoir window, central Idaho

Documentation of Devonian continental-shelf shallow-water carbonate rocks in the core of the Fish Creek Reservoir window shifts the known westernmost limit of the Devonian miogeosyncline 50 km (30 mi) southwest across the structural grain from the well-known miogeosynclinal sequence in the Lost River Range. The miogeosynclinal carbonate sequence in the window has a minimum thickness of 450 m (1,500 ft). It comprises the upper Lower Devonian (Emsian) and lower Middle Devonian (Eifelian) Carey Dolomite (new), the upper Middle Devonian (Givetian) and Upper Devonian Jefferson Formation, and the Upper Devonian Picabo Formation (new). Conodont faunas precisely date the Carey. The Picabo Formation, composed of interbedded sandy dolomite-pebble conglomerate and dolomitic quartzose sandstone, is unlike any previously described formation of Late Devonian or Early Mississippian age in central Idaho. It resembles parts of the Stansbury, Beirdneau, Leatham, and Victoria Formations, which reflect areas of local Late Devonian uplift and erosion of older shelf rocks in northern Utah and southeastern Idaho. Transitional (continental-slope) rocks of the Roberts Mountains Formation representing reef and offreef facies are thrust over the Devonian shelf sequence within the Fish Creek Reservoir window. The Roberts Mountains Formation here is precisely dated as latest Silurian (Pridolian, eosteinhornensis Zone) through earliest Devonian (Lochkovian) by a sequence of conodont faunas. The easternmost known exposures of possible Devonian siliceous facies rocks assigned to the Milligen(?) Formation are present less than 4.8 km (3 mi) southwest of the shelf sequence. Structural relations and paleotectonic reconstructions suggest that they have a minimum eastward translation of 32 km (20 mi). The Devonian continent-ocean basin interface, along which the Antler orogenic belt developed at this latitude, probably was located near the east edge of the present Idaho batholith.

Idaho↗
USGS2015

Groundwater availability of the Columbia Plateau Regional Aquifer System, Washington, Oregon, and Idaho

The Columbia Plateau Regional Aquifer System (CPRAS) covers about 44,000 square miles of southeastern Washington, northeastern Oregon, and western Idaho. The area supports a $6-billion per year agricultural industry, leading the Nation in production of apples, hops, and eight other commodities. Groundwater pumpage and surface-water diversions supply water to croplands that account for about 5 percent of the Nation’s irrigated lands. Groundwater also is the primary source of drinking water for the more than 1.3 million people in the study area. Increasing competitive demands for water for municipal, fisheries/ecosystems, agricultural, domestic, hydropower, and recreational uses must be met by additional groundwater withdrawals and (or) by changes in the way water resources are allocated and used throughout the hydrologic system. As of 2014, most surface-water resources in the study area were either over allocated or fully appropriated, especially during the dry summer season. In response to continued competition for water, numerous water-management activities and concerns have gained prominence: water conservation, conjunctive use, artificial recharge, hydrologic implications of land-use change, pumpage effects on streamflow, and effects of climate variability and change. An integrated understanding of the hydrologic system is important in order to implement effective water-resource management strategies that address these concerns. To provide information to stakeholders involved in water-management activities, the U.S. Geological Survey (USGS) Groundwater Resources Program assessed the groundwater availability as part of a national study of regional systems (U.S. Geological Survey, 2008). The CPRAS assessment includes: The present status of groundwater resources, How these resources have changed over time, and Development and application of tools to estimate system responses to stresses from future uses and climate variability and change. This effort builds on previous investigations, especially the USGS Columbia Plateau Regional Aquifer-System Analysis study (CP-RASA). A major product of this new assessment is a numerical groundwater-flow model of the system. The model was used to estimate water-budget components of the hydrogeologic units composing the groundwater system, and to evaluate groundwater availability under existing land- and water-use conditions and a possible future climate scenario representing an increase in pumpage demand due to a warming climate. Information from this study also allowed for analysis of: The CPRAS for predevelopment times (pre-1920), Variations from 1920 through 2007, Conditions during 1985–2007 (referred to as “existing conditions”), and Changes in the system from predevelopment times. The model also is a useful tool for investigating water supply, water demand, management strategies, groundwater-surface water exchanges, and potential effects of changing climate on the hydrologic system.

Idaho, Oregon, Washington↗
USGS2024

Hydrogeologic framework and extent of saltwater intrusion in Kings, Queens, and Nassau Counties, Long Island, New York

In 2016, the U.S. Geological Survey began a multiyear cooperative study with the New York State Department of Environmental Conservation to evaluate the sustainability of Long Island’s sole-source aquifer system through hydrogeologic mapping, compilation of groundwater chloride concentrations, and groundwater flow modeling. In the initial phase of the islandwide study, the hydrogeologic framework and extent of saltwater intrusion in aquifers in Kings, Queens, and Nassau Counties on western Long Island, N.Y., were investigated. The aquifer system underlying western Long Island has been under stress from pumping of public, irrigation (golf course), and industrial supply wells. Saltwater intrusion has occurred from surrounding embayments (East River, Long Island Sound, Jamaica Bay, and the Atlantic Ocean) due to pumping. Eighteen boreholes were drilled and cores taken during 2019–21 to collect hydrogeologic, geochemical, and geophysical data to delineate the complex subsurface hydrogeology and extent of saltwater intrusion within the study area. Evaluation of the new cores, reexamination of legacy core descriptions, and analysis of borehole geophysical logs was used to refine the previously published hydrogeologic framework of Pleistocene and Cretaceous unconsolidated sediments in the area, including delineation of a previously undefined hydrogeologic unit between the Magothy aquifer and the Raritan confining unit, herein named the “upper Raritan aquifer.” The upper Raritan aquifer was first recognized in southeastern Nassau County from an analysis of about 50 closely spaced boreholes with high-resolution core descriptions and gamma-ray (gamma) logs. Further analysis of borehole logs across the study area indicated that the upper Raritan aquifer was also present in Kings and Queens Counties. Nuclear magnetic resonance (NMR) logging was used for the first time on Long Island to provide estimates of the hydraulic properties of the major aquifer and confining units. Unlike other geophysical logs that record responses to the rock matrix and fluid properties and are strongly dependent on mineralogy, NMR logs record responses to the presence of hydrogen protons in the formation fluid to determine water fraction and pore-size distribution. NMR log analysis provided estimates of the clay-bound, capillary-bound, and mobile water fractions and hydraulic conductivity of aquifers and confining units penetrated by five wells in Nassau County. Pumpage for public-supply and industrial wells on Long Island began in the 1870s with small, localized suppliers of populated areas in Kings and Queens Counties. By 1904–16, pumpage for public water supply in Kings County averaged 21 million gallons per day, and averaged 37 million gallons per day in Queens County, mostly from the upper glacial aquifer. Saltwater intrusion was reported as early as the beginning of the 20th century and included the upper glacial-Jameco-Magothy and Lloyd-North Shore aquifer systems. By 1936, pumping in central Kings County created a major cone of depression in the water table extending to the south shore of much of Kings County and into southwestern Queens County. Saltwater intrusion has caused the shutdown of public-supply wells in Kings, Queens, and Nassau Counties. A large saltwater intrusion wedge in the Lloyd aquifer was indicated in southern Queens County in the early part of the 20th century, and the saltwater interface may have been onshore predevelopment. Most of Kings and Queens Counties are intruded with saltwater in both the upper glacial-Jameco-Magothy and Lloyd-North Shore aquifers systems. Saltwater increased during the 20th century and continues to increase to the present (2023) in the Lloyd-North Shore aquifer system in Great Neck and Manhasset Neck in northern Nassau County. A major wedge of saltwater intrusion in the upper glacial-Jameco-Magothy aquifer in southwestern Nassau County appears to be increasing.

New York↗
USGS1994

Evolution of volcanic and tectonic features in caldera settings and their importance in the localization of ore deposits

Many calderas are located along regionally important fault zones that are intermittently active before and after the caldera cycle. In mineralized calderas, the ore deposits are controlled by structures developed during caldera formation and by regional faults which intersect and reactivate the caldera-related structures. In the earliest phase of the caldera cycle, tumescence occurs over the shallowly emplaced magma chamber and normal faults develop within the structural dome above the magma chamber. This early phase of faulting is disrupted by caldera formation but some of the faults are preserved outside the caldera margin and may become important ore-controlling structures such as the Ruja mercury deposit in the McDermitt caldera complex, Nevada, and the precious metal deposits in the Atlanta district, Nevada, outside the Indian Peak caldera. Caldera-related structures such as ring fracture faults are commonly the most important in controlling the emplacement of resurgent magma, as well as postcollapse intrusions and associated ore deposits. During the resurgence phase of the caldera, faults related to an apical graben, and radial and ring faults and fractures form and may extend outside the collapse structure. Radial and ring faults and fractures provided the structural control for gold alunite-type deposits in the Rodalquilar caldera complex, Spain.At the end of the caldera cycle, the area over the batholith related to the caldera-forming magma chambers is uplifted as isostatic compensation occurs, or subsides if the volcanic field is developed within a rapidly subsiding graben. Volume change resulting from crystallization will also contribute to subsidence. Regional subsidence of the Lake Owyhee volcanic field in southeastern Oregon at the end of the caldera cycle is reflected by arkosic sedimentation in the caldera basins and throughout the eastern part of the volcanic field. Crystallization of the underlying batholith permits the reestablishment of brittle deformation along the regional faults which initially may have controlled magma emplacement. This tectonic activity may reactivate caldera structures and these typically become important for localization of hydrothermal activity. Hot spring-type gold deposits in the Lake Owyhee volcanic field formed when a regional northwest-trending structure reactivated the caldera ring fracture fault zone of the Three Fingers caldera. The formation of hydrothermal ore deposits at the end of the caldera cycle is often related to tectonic reactivation of caldera structures by regional faults and emplacement of small volumes of magma as stocks and vent complexes along these structures.

Economic Geology↗
USGS2023

Status of water-level altitudes and long-term and short-term water-level changes in the Chicot and Evangeline (undifferentiated) and Jasper aquifers, greater Houston area, Texas, 2022

Since the early 1900s, groundwater withdrawn from the primary aquifers that compose the Gulf Coast aquifer system—the Chicot, Evangeline, and Jasper aquifers—has been an important source of water in the greater Houston area, Texas. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting the status of water-level altitudes and water-level changes in these aquifers in the greater Houston area. In this report, the Chicot and Evangeline aquifers are treated as a single hydrogeologic unit for the purposes of providing annual assessments of regional-scale water-level altitudes and changes over time. In 2022, shaded depictions of water-level altitudes for the Chicot and Evangeline aquifers (undifferentiated) ranged from about 270 feet (ft) below the North American Vertical Datum of 1988 (NAVD 88) to about 195 ft above NAVD 88. The largest decline in water-level altitudes indicated by the 1977–2022 long-term water-level-change map was southeast of The Woodlands. In comparison, the 1990–2022 long-term water-level-change map depicts declines in water-level altitudes in localized areas at or near certain wells in parts of northwestern Harris County and southern Montgomery County. The largest rise in water-level altitudes for 1977–2022 was observed in a relatively large area in southeastern Harris County, whereas the largest rise in water-level altitudes for 1990–2022 was observed in a relatively small area in central Harris County. The 5-year short-term water-level-change map depicts the largest declines at three wells in northern Fort Bend County and the largest rises at five wells in southwestern and central Harris County. The 1-year short-term water-level-change map depicts the largest decline at a well in north-central Harris County and the largest rises at a well in north-central Fort Bend County and a well in southwestern Harris County. In 2022, shaded depictions of water-level altitudes for the Jasper aquifer ranged from about 213 ft below NAVD 88 to about 285 ft above NAVD 88. The 2000–22 long-term water-level-change map depicts water-level declines throughout most of the study area where water-level-measurement data from the aquifer were collected, with the largest decline in north-central Harris County and south-central Montgomery County south of The Woodlands. The 5-year short-term water-level-change map depicts the largest decline at a well in Conroe and the largest rise at a well in south-central Montgomery County. The 1-year short-term water-level-change map depicts the largest decline at a well in south-central Montgomery County east of The Woodlands and the largest rise at a well in Conroe.

Texas↗
USGS2022

Status of water-level altitudes and long-term water-level changes in the Chicot and Evangeline (undifferentiated) and Jasper aquifers, greater Houston area, Texas, 2021

Since the early 1900s, groundwater withdrawn from the primary aquifers that compose the Gulf Coast aquifer system—the Chicot and Evangeline (undifferentiated) and Jasper aquifers—has been the primary source of water in the greater Houston area, Texas. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting the status of water-level altitudes and water-level changes in aquifers in the greater Houston area. In contrast to previous reports, the Chicot and Evangeline aquifers are treated as a single hydrogeologic unit in this report. In 2021, shaded depictions of water-level altitudes for the Chicot and Evangeline aquifers (undifferentiated) ranged from 300 feet (ft) below the North American Vertical Datum of 1988 (NAVD 88) to 300 ft above NAVD 88. The largest decline in water-level altitudes indicated by the 1977–2021 long-term water-level-change map for the Chicot and Evangeline aquifers (undifferentiated) was in the north-central part of The Woodlands, Tex., whereas the 1990–2021 long-term water-level-change map for the Chicot and Evangeline aquifers (undifferentiated) depicts a large area of decline in water-level altitudes in northwestern Harris County, northwest of Jersey Village, Tex. The largest rise in water-level altitudes in the Chicot and Evangeline aquifers (undifferentiated) was observed in a relatively large area in southeastern Harris County for 1977–2021, whereas the largest rise in water-level altitudes for 1990–2021 was in a relatively large area in central Harris County. In 2021, shaded depictions of water-level altitudes for the Jasper aquifer ranged from 250 ft below NAVD 88 to 300 ft above NAVD 88. The 2000–21 long-term water-level-change map for the Jasper aquifer depicts water-level declines throughout most of the study area where water-level-altitude data from the Jasper aquifer were collected, with the largest decline in northern Harris County southwest of The Woodlands.

Texas↗
USGS1959

Geology and ground-water resources of the upper Lodgepole Creek drainage basin, Wyoming, with a section on chemical quality of the water

The principal sources of ground-water supply in the upper Lodgepole Creek drainage basin-the part of the basin west of the Wyoming-Nebraska State line-are the Brule formation of Oligocene age, the Arikaree formation of Miocene age, the Ogallala formation of Pliocene age, and the unconsolidated deposits of Quaternary age. The Brule formation is a moderately hard siltstone that generally is not a good aquifer. However, where it is fractured or where the upper part consists of pebbles of reworked siltstone, it will yield large quantities of water to wells. Many wells in the Pine Bluffs lowland, at the east end of the area, derive water from the Brule. The Arikaree formation, which consists of loosely to moderately cemented fine sand, will yield small quantities of water to wells but is not thick enough or permeable enough to supply sufficient water for irrigation. Only a few wells derive water from it. The Ogallala formation consists of lenticular beds of clay, silt, sand, and gravel which, in part, are cemented with calcium carbonate. Only the lower part of the formation is saturated. Nearly all the wells in the upland part of the area tap the Ogallala, but they supply water in amounts sufficient for domestic and stock use only. Two of the wells have a moderately large discharge, and other wells of comparable discharge probably could be drilled in those parts of the upland where the saturated part of the Ogallala is fairly thick. Most of the unconsolidated deposits of Quaternary age are very permeable and, where a sufficient thickness is saturated, will yield large quantities of water to wells. These deposits are a significant source of water supply in the southeastern part of the area. The Chadron formation of Oligocene age, which underlies the Brule formation, is a medium- to coarse-grained sandstone where it crops out in the Islay lowland. No wells tap the Chadron, but it probably would yield small quantities of water to wells. It lies at a relatively shallow depth beneath most of the Islay lowland, near the west end of the area, and at a depth of about 800 feet beneath the Pine Bluffs lowland. In the latter area it probably is finer grained and may not be permeable enough to yield water to wells. All the ground water in the area is derived from precipitation. It is estimated that about 5 percent of the precipitation infiltrates directly to the zone of saturation. The remainder either is evaporated immediately; is retained by the soil, later to be evaporated or transpired; or is discharged by overland flow to the surface drainage courses. Most of the water that reaches the surface drainage courses eventually sinks to the zone of saturation or is evaporated. The slope of the water table and the movement of ground water are generally eastward. The depth to water ranges from less than 10 feet in parts of the valley to about 300 feet in the upland areas. In much of the Pine Bluffs lowland, the depth to water is less than 50 feet. Ground water not pumped from wells within the area is discharged by evapotranspiration where the water table is close to the land surface, by outflow into streams, or by underflow eastward beneath the State line. The chemical quality of ground water from the principal sources is remarkably uniform, and the range in concentration of dissolved constituents is narrow. In general, the water is of the calcium bicarbonate type, is hard (hardness as CaC03 is as high as 246 ppm), and contains less than about 400 parts per million of dissolved solids, which is a moderate mineralization. Silica constitutes a large proportion of the dissolved solids. The water is suitable for irrigation and, except for iron in water from some wells that tap the Ogallala formation, meets the drinking water standards of the U.S. Public Health Service for chemical constituents. Because the water is siliceous, alkaline, and hard, it is unsuitable for many industrial uses unless treated.

Water Supply Paper↗
USGS2002

Hydrogeology and simulation of ground-water flow and land-surface subsidence in the Chicot and Evangeline aquifers, Houston area, Texas

In November 1997, the U.S. Geological Survey, in cooperation with the City of Houston Utilities Planning Section and the City of Houston Department of Public Works & Engineering, began an investigation of the Chicot and Evangeline aquifers in the greater Houston area in Texas to better understand the hydrology, flow, and associated land-surface subsidence. The principal part of the investigation was a numerical finite-difference model (MODFLOW) developed to simulate ground-water flow and land-surface subsidence in an 18,100-square-mile area encompassing greater Houston. The focus of the study was Harris and Galveston Counties, but other counties were included to achieve the appropriate boundary conditions. The model was vertically discretized into three 103-row by 109-column layers resulting in a total of 33,681 grid cells. Layer 1 represents the water table using a specified head, layer 2 represents the Chicot aquifer, and layer 3 represents the Evangeline aquifer. Simulations were made under transient conditions for 31 ground-water-withdrawal (stress) periods spanning 1891–1996. The years 1977 and 1996 were chosen as potentiometric-surface calibration periods for the model. Simulated and measured potentiometric surfaces of the Chicot and Evangeline aquifers for 1977 match closely. Waterlevel measurements indicate that by 1977, large ground-water withdrawals in east-central and southeastern areas of Harris County had caused the potentiometric surfaces to decline as much as 250 feet below sea level in the Chicot aquifer and as much as 350 feet below sea level in the Evangeline aquifer. Simulated and measured potentiometric surfaces of the Chicot and Evangeline aquifers for 1996 also match closely. The large potentiometric-surface decline in 1977 in the southeastern Houston area showed significant recovery by 1996. The 1996 centers of potentiometric-surface decline are located much farther northwest. Potentiometric-surface declines of more than 200 feet below sea level in the Chicot aquifer and more than 350 feet below sea level in the Evangeline aquifer were measured in observation wells and simulated in the flow model. Simulation of land-surface subsidence and water released from storage in the clay layers was accomplished using the Interbed-Storage Package of the MODFLOW model. Land-surface subsidence was calibrated by comparing simulated long-term (1891–1995) and short-term (1978–95) land-surface subsidence with published maps of land-surface subsidence for about the same period until acceptable matches were achieved. Simulated 1996 Chicot aquifer flow rates indicate that a net flow of 562.5 cubic feet per second enters the Chicot aquifer in the outcrop area, and a net flow of 459.5 cubic feet per second passes through the Chicot aquifer into the Evangeline aquifer. The remaining 103.0 cubic feet per second of flow is withdrawn as pumpage, with a shortfall of about 84.9 cubic feet per second supplied to the wells from storage in sands and clays. Water simulated from storage in clays in the Chicot aquifer is about 19 percent of the total water withdrawn from the aquifer. Simulated 1996 Evangeline aquifer flow rates indicate that a net flow of 14.8 cubic feet per second enters the Evangeline aquifer in the outcrop area, and a net flow of 459.5 cubic feet per second passes through the Chicot aquifer into the Evangeline aquifer for a total inflow of 474.3 cubic feet per second. A greater amount, 528.6 cubic feet per second, is withdrawn by wells; the shortfall of about 54.8 cubic feet per second is supplied from storage in sands and clays. Water simulated from storage in clays in the Evangeline aquifer is about 10 percent of the total water withdrawn from the aquifer.

Texas↗
USGS2005

Late Quaternary eolian and alluvial response to paleoclimate, Canyonlands, southeastern Utah

In upland areas of Canyonlands National Park, Utah, thin deposits and paleosols show late Quaternary episodes of eolian sedimentation, pedogenesis, and climate change. Interpretation of the stratigraphy and optically stimulated luminescence ages of eolian and nearby alluvial deposits, their pollen, and intercalated paleosols yields the following history: (1) Eolian deposition at ca. 46 ka, followed by several episodes of alluviation from some time before ca. 40 ka until after 16 ka (calibrated). (2) Eolian deposition from ca. 17 ka to 12 ka, interrupted by periods of pedogenesis, coinciding with late Pleistocene alluviation as local climate became warmer and wetter. (3) A wetter period from 12 to 8.5 ka corresponding to the peak of summer monsoon influence, during which soils formed relatively quickly by infiltration of eolian silt and clay, and trees and grasses were more abundant. (4) A drier period between ca. 8.5 and 6 ka during which sheetwash deposits accumulated and more desertlike vegetation was dominant; some dunes were reactivated at ca. 8 ka. (5) Episodic eolian and fluvial deposition during a wetter, cooler period that began at ca. 6 ka and ended by ca. 3-2 ka, followed by a shift to drier modern conditions; localized mobilization of dune sand has persisted to the present. These interpretations are similar to those of studies at the Chaco dune field, New Mexico, and the Tusayan dune field, Arizona, and are consistent with paleoclimate interpretations of pollen and packrat middens in the region. A period of rapid deposition and infiltration of eolian dust derived from distant igneous source terranes occurred between ca. 12 and 8 ka. Before ca. 17 ka, and apparently back to at least 45 ka, paleosols contain little or no such infiltrated dust. After ca. 8 ka, either the supply of dust was reduced or the more arid climate inhibited translocation of dust into the soils. ?? 2005 Geological Society of America.

Geological Society of America Bulletin↗
USGS2010

Trends in base flow, total flow, and base-flow index of selected streams in and near Oklahoma through 2008

The U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, investigated trends in base flow, total flow, and base-flow index of selected streams in Oklahoma and evaluated possible causes for trends. Thirty-seven streamflow-gaging stations that had unregulated or moderately regulated streamflow were selected for trend analysis. Statistical evaluation of trends in annual and seasonal (winter-spring and summer-autumn) base flow, total flow, and base-flow index at 37 selected streamflow-gaging stations in Oklahoma was performed by using a Kendall's tau trend test. This trend analysis also was performed for annual and seasonal precipitation for nine climate divisions in the study area, annual peak flows, the number of days where flow was zero or less than 1 cubic foot per second (both annually and seasonally), and annual winter groundwater levels for 35 shallow wells near the analyzed stations. Precipitation-adjusted trends using LOESS regressions and Kendall's tau were computed for annual and seasonal base-flow and total-flow volumes in order to identify the presence of underlying trends in streamflow that are not associated with annual or seasonal variations in precipitation. In general, upward trends in precipitation were detected for climate divisions in north-central Oklahoma and south-central and southeastern Kansas. More climate divisions had statistically significant upward trends in total precipitation for annual water years than in winter-spring or summer-autumn water years. Significant trends in annual or seasonal base-flow volume were detected for 22 stations, 19 of which had trends that were upward in direction. Significant trends in annual or seasonal total-flow volume were detected for 14 stations, 9 of which had trends that were upward in direction. Most stations that had significant upward trends in annual or seasonal total-flow volume also had significant upward trends in base-flow volume for the same period. Precipitation adjustment changed the results (significant only or significance and direction) of significant annual or seasonal trends in unadjusted base-flow volume for 12 stations and in unadjusted total-flow volume for 13 stations. Significant trends in annual or seasonal base-flow index were detected for 25 stations, 23 of which had trends that were upward in direction. Eighteen stations that had significant upward trends in annual or seasonal base-flow index also had significant upward trends in base-flow volume and no significant downward trends in total-flow volume during the same period, which indicated that upward trends in base-flow index were likely driven by increases in base flow at these stations. Trend results were highly variable throughout the State. However, some recurring patterns in locations of stations with similar trend results were detected. In general, significant downward trends in base-flow and total-flow volumes were detected for the three stations in the Oklahoma Panhandle. Significant upward trends in annual or seasonal base-flow volume before and after precipitation adjustment were detected for 12 stations in southwestern and central Oklahoma. In eastern Oklahoma, significant upward trends in annual or seasonal base-flow volume were only detected for 4 stations, and significant upward trends in annual or seasonal total-flow volume were only detected for 1 station. After precipitation adjustment no stations in this region had significant upward trends in either parameter, one station had significant downward trends in annual base-flow volume, and one station had significant downward trends in winter-spring total-flow volume. Increases in annual and seasonal precipitation, especially during a substantial wet period (1980-2000), may be one of the factors resulting in upward trends in base-flow volume and total-flow volume at many of the stations analyzed in this report. Eleven stations with significant upward trends in precipitation-adjust

Scientific Investigations Report↗
USGS2020

Spatially referenced models of streamflow and nitrogen, phosphorus, and suspended-sediment loads in the southeastern United States

Spatially Referenced Regression On Watershed attributes (SPARROW) models were applied to describe and estimate mean-annual streamflow and transport of total nitrogen (TN), total phosphorus (TP), and suspended sediment (SS) in streams and delivered to coastal waters of the southeastern United States on the basis of inputs and management practices centered near 2012, the base year of the model. Previously published TN and TP models for 2002 served as a starting point and reference for comparison. The datasets developed for the 2012 models not only represent updates of previous conditions but also incorporate new approaches for characterizing sources and transport processes that were not available for previous models. Variability in streamflow across the southeastern United States was explained as a function of precipitation adjusted for evapotranspiration, spring discharge, and municipal and domestic wastewater discharges to streams. Results from the streamflow model were used as input to the water-quality SPARROW models, and areas with large streamflow prediction errors—urban areas and karst areas—were used to provide guidance on where additional data are needed to improve routing of flow. Variability in TN transport in Southeast streams was explained by the following five sources in order of decreasing mass contribution to streams: atmospheric deposition, agricultural fertilizer, municipal wastewater, manure from livestock, and urban land. Variable rates of TN delivery from source to stream were attributed to variation among catchments in climate, soil texture, and vegetative cover, including the extent of cover crops in the watershed. Variability in TP transport in Southeast streams was explained by the following six sources in order of decreasing mass contribution to streams: parent-rock minerals, urban land, manure from livestock, municipal wastewater, agricultural fertilizer, and phosphate mining. Varying rates of TP delivery were attributed to variation in climate, soil erodibility, depth to water table, and the extent of conservation tillage practices in the watershed. Variability in SS transport in Southeast streams was explained by variable sediment export rates for different combinations of land cover and geologic setting (for upland sources of sediment) and by gains in stream power caused by longitudinal changes in channel hydraulics (for channel sources of sediment). Sediment yields for the transitional land cover (shrub, scrub, herbaceous, and barren) varied widely depending on geologic setting and on agricultural land cover. Varying rates of SS delivery, like those for TP, were attributed to variation in climate, soil erodibility, and the extent of conservation tillage practices in the watershed, as well as to areal extent of canopy land cover in the 100-meter buffer along the channel. Relatively large uncertainty, compared to the other three models, for almost all the SS source coefficients indicates the need for caution when interpreting the results from the sediment model. TN, TP, and SS inputs to streams from sources were balanced in the models with losses from physical processes in streams and reservoirs and with water withdrawals. The losses in streams and reservoirs along with withdrawals removed 35, 44, and 65 percent of the TN, TP, and SS load, respectively, that entered streams before reaching coastal waters.

Scientific Investigations Report↗
USGS2023

Unzipping supercontinent Pangea: Geologic, potential field data, and buried structures, and a case for sequential Atlantic opening

Amalgamation of Pangea culminated with zippered N-to-S closing of the Theic ocean during the Alleghanian orogeny. Transpressional-rotational collision produced widespread dextral faulting throughout the eastern Appalachian hinterland, and thrust faulting in the western hinterland and foreland. The partially buried southern Appalachian Eastern Piedmont fault system is a product of late Paleozoic transpressional dextral faulting. Eastern Piedmont fault system faults are cut by two 200–190 Ma Central Atlantic Magmatic Province (CAMP) diabase dike sets (∼NW and N S), which postdate initial rifting, producing the Late Triassic-Early Jurassic basins. Sinistral reactivation of suitably oriented Paleozoic faults (e.g., Towaliga) that offset Jurassic dikes implies faulting is coeval with CAMP dike emplacement, or occurred very soon after 200–190 Ma dike emplacement. A large NE-striking sinistral fault (Estill fault) offsets magnetic and gravity highs in the Brunswick (Charleston) terrane in South Carolina and Georgia. This fault is at least 185 km long, with ca. 75–80 km maximum of sinistral separation. The Estill fault geometry agrees with the stress field associated with Central Atlantic Magmatic Province dike emplacement. We conclude that movement along the Estill and other sinistral faults represents Early Jurassic displacement that is well documented in eastern North America prior to Atlantic opening. The early Mesozoic post-failed rifting (basin formation) preceded dike emplacement and pre-spreading sinistral faulting. We recognize four stages in the Late Triassic–Jurassic tectonics and kinematics of eastern North America based on field, crosscutting relationships, and available geophysical data: (1) initial W-to-E failed transtensional rifting with formation of the S-to-N-younging Triassic-Jurassic basins; (2) CAMP diabase dikes intruded 200–190 Ma; (3) sinistral movement of large blocks of crust in the North Atlantic region including southeastern North America; and (4) spreading and opening of the Atlantic Ocean 195–170 Ma. These stages mark the reversal of Alleghanian rotational dextral transpressional (zippered) collision forming Pangea supercontinent and ‘unzipping’ the supercontinent prior to Atlantic opening.

Alabama, Georgia↗
USGS2000

Prodigious polyphyly in imperilled freshwater pearly-mussels (Bivalvia: Unionidae): a phylogenetic test of species and generic designations

Unionid bivalves or freshwater pearly-mussels (Unionoidea: Unionidae) serve as an exemplary system for examining many of the problems facing systematists and conservation biologists today. Most of the species and genera were described in the late 1800s and early 1900s, but few phylogenetic studies have been conducted to test conventional views of species and classification. Pearly-mussels of Gulf Coastal drainages of the southeastern United States from the Escambia (southern Alabama to Florida) to the Suwannee Rivers (Florida) are a unique fauna comprised of approximately 100 species, with about 30 endemic to the region. In this study, mitochondrial cytochrome c oxidase subunit I and 16S rRNA gene sequences were used to test the monophyly and to estimate evolutionary relationships of five unionid species representing three different genera. The molecular phylogenies depict all three genera as polyphyletic. The prodigious polyphyly exhibited within unionids is due to incorrect notions of homology and false assumptions about missing anatomical data. In contrast, the molecular phylogeny provides evidence to support the recognition of all five unionid species as distinct evolutionary entities. Furthermore, molecular genealogical evidence supports the elevation of Quincuncina infucata (Conrad) of the Suwannee River to species level, for which Q. kleiniana (Lea) is available.

Geological Society Special Publication↗
USGS1998

Evidence for faulting related to dissociation of gas hydrate and release of methane off the southeastern United States

This paper is part of the special publication Gas hydrates: relevance to world margin stability and climatic change (eds J.P. Henriet and J. Mienert). An irregular, faulted, collapse depression about 38 x 18 km in extent is located on the crest of the Blake Ridge offshore from the south- eastern United States. Faults disrupt the sea floor and terminate or sole out about 40-500 m below the sea floor at the base of the gas hydrate stable zone, which is identified from the location of the bottom simulating reflection (BSR). Normal faults are common but reverse faults and folds also are widespread. Folds commonly convert upward into faults. Sediment diapirs and deposits of sediments that were erupted onto the sea floor are also present. Sea-floor depressions at faults may represent locations of liquid/gas vents. The collapse was probably caused by overpressures and by the decoupling of the overlying sediments by gassy muds that existed just beneath the zone of gas hydrate stability.

Blake Ridge↗
USGS1985

Reconnaissance geology of the Al Ba'ayith quadrangle, sheet 26/41 D, Kingdom of Saudi Arabia

The Al Ba'ayith quadrangle, located in the northeastern part of the Arabian Shield, is underlain by upper Proterozoic intrusive rocks and volcanogenic layered sequences bounded by unconformities. The oldest rocks are silicic volcanic rocks of the Banana formation that is tentatively assigned to the Hulayfah group. Successively younger layered rocks are the Maraghan formation of the Murdama group, consisting of lithic graywacke, siltstone, and shale; the Hibshi formation, coarse-grained lithic sandstone and conglomerate; the Sufran formation, dacitic and andesitic lava flows and ash-flow tuffs; the Jurdhawiyah formation, andesitic flows and agglomerate, and conglomeratic sandstone; and the Hadn formation, rhyolite flows and ash-flow tuffs, conglomerate, sandstone, and andesite flows. Plutonic rocks are of four main age groups: an early group consisting of orthogneiss of granodioritic and granitic composition, and metagabbro; a pre-Hibshi group consisting of the Murran complex (diorite and quartz diorite) and quartz monzodiorite; a post-Hibshi group, consisting of altered mafic plutonic rocks, granodiorite of the Idah suite, and monzogranite of the Shuwayman suite; and a latest Precambrian group of highly evolved granitic rocks, consisting of alkali-feldspar granite, granophyre, and syenogranite. Structures in the orthogneiss and metagabbro trend northeast to northwest, and in the Murran complex, generally east. The Maraghan formation was folded and thrust over the Hibshi formation along the northeast-trending Raha fault. The Jurdhawiyah formation is at the northern margin of the east-trending Shuqrah basin. Northwest-trending left-lateral faults probably belong to the Najd fault system. Quaternary surficial deposits mantle large areas of the quadrangle, and consist of sheet gravel, alluvial fan gravel, eolian and alluvial sand and silt, and sabkhah deposits. Gold-bearing quartz veins occur associated with small plutons of the Idah suite in the southeastern part of the quadrangle, and have been mined in the past. Ironstones, near Murran in the center of the quadrangle contain trace amounts of silver and gold.

Open-File Report↗