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At least 775 records · Page 43Linked to original sources
USGS2014

Himalayan gneiss dome formation in the middle crust and exhumation by normal faulting: New geochronology of Gianbul dome, northwestern India

A general lack of consensus about the origin of Himalayan gneiss domes hinders accurate thermomechanical modeling of the orogen. To test whether doming resulted from tectonic contraction (e.g., thrust duplex formation, antiformal bending above a thrust ramp, etc.), channel flow, or via the buoyant rise of anatectic melts, this study investigates the depth and timing of doming processes for Gianbul dome in the western Himalaya. The dome is composed of Greater Himalayan Sequence migmatite, Paleozoic orthogneiss, and metasedimentary rock cut by multiple generations of leucogranite dikes. These rocks record a major penetrative D2 deformational event characterized by a domed foliation and associated NE-SW–trending stretching lineation, and they are flanked by the top-down-to-the-SW (normal-sense) Khanjar shear zone and the top-down-to-the-NE (normal sense) Zanskar shear zone (the western equivalent of the South Tibetan detachment system). Monazite U/Th-Pb geochronology records (1) Paleozoic emplacement of the Kade orthogneiss and associated granite dikes; (2) prograde Barrovian metamorphism from 37 to 33 Ma; (3) doming driven by upper-crustal extension and positive buoyancy of decompression melts between 26 and 22 Ma; and (4) the injection of anatectic melts into the upper levels of the dome—neutralizing the effects of melt buoyancy and potentially adding strength to the host rock—by ca. 22.6 Ma on the southwestern flank and ca. 21 Ma on the northeastern flank. As shown by a northeastward decrease in 40 Ar/ 39 Ar muscovite dates from 22.4 to 20.2 Ma, ductile normal-sense displacement within the Zanskar shear zone ended by ca. 22 Ma, after which the Gianbul dome was exhumed as part of a rigid footwall block below the brittle Zanskar normal fault, tilting an estimated 5°–10°SW into its present orientation.

Gianbul dome↗
USGS1989

Inner shelf deposits of the Louisiana-Mississippi-Alabama region, Gulf of Mexico

The late Quaternary morphology, shallow stratigraphy and sediment distribution of the Louisiana-Mississippi-Alabama inner shelf region are the product of transgressive and regressive sedimentary processes. Shelf sedimentary facies were deposited by deltaic progradation, followed by shoreface erosion and submergence. This information is based on interpretations and synthesis of more than 4,160 mi (6,700 km) of high resolution seismic profiles, 75 grab samples, and 77 vibracores. The shelf can be divided into two main depositional regions. The southwestern region, east and south of the Mississippi River plain, was formed by early Holocene delta complexes, overlying a late Wisconsinan delta. Deposits of the late Wisconsinan delta consist of well-defined coarsening-upward sequences and represent deltaic progradation during low sea level stands. The relatively recent Mississippi delta complexes have deposits which consist of fine-grained sands, silt and clay. With the late Holocene rise in sea level, asymmetrical sand ridges (16 ft, or 5 m, relief) have formed due to marine reworking of shoreline features. The northeastern region, offshore of the Mississippi-Alabama barrier islands, was formed by Pleistocene fluvial systems and Recent shoreface erosion and ravinement. Underlying the relatively thin Holocene sediment cover are relict fluvial sands which were deposited during the late Wisconsinan lowstand. Subsequent sea level rise allowed marine processes to rework and redistribute sediments forming the nearshore fine-grained facies and shelf sands sheet.

Gulf of Mexico↗
USGS2015

Coastal plain pond water quality and mercury contend of biota of the Long Island Central Pine Barrens and Mashomack Preserve: Effects of atmospheric deposition and human development

Pine barrens are considered an imperiled ecosystem in the northeastern U.S. The Suffolk County Pine Barrens, once the second largest in the Northeast, were substantially reduced and fragmented by development during the 20th century. The coastal plain ponds being considered in this study occur in central Suffolk County within the Long Island Central Pine Barrens region. This highly unique natural environment, embedded with forests and woodlands, resulted from its glacial origins and a land use history that predates European colonization. Included in this study was The Nature Conservancy’s Mashomack Preserve, located on Shelter Island between Peconic Bay and Gardiner’s Bay. There are no freshwater ponds in the Mashomack Preserve, but this area was included with the Central Pine Barrens investigation, because Shelter Island has a similar geologic and land-use history that has resulted in a similarly unique low-nutrient forest and woodland ecosystem with extremely coarse-textured soils.

New York↗
USGS2013

Hurricane Irene and associated floods of August 27-30, 2011, in New Jersey

Intense rainfall from Hurricane Irene during August 27–30, 2011, inundated streams throughout New Jersey resulting in peak streamflows exceeding the 100-year recurrence interval at many streamgages and causing heavy property and road damage. The rain event affected the entire State. Some notably affected areas were the Passaic and Hackensack River Basins in northeastern New Jersey with new peaks of record at 10 continuous-record streamflow-gaging stations on streams such as the Hackensack River, Ramapo River, Rockaway River, and Green Pond Brook. In the Atlantic Coastal Basin, new peaks of record were recorded at 6 continuous-record streamflow-gaging stations, 2 of which were on the Manasquan River, 1 on Toms River, 1 on the Mullica River, 1 on the North Branch Metedeconk River, and 1 on the West Branch Wading River. Several tributaries to the Delaware River, such as the Pequest River, Flat Brook, and Assunpink Creek, also experienced major flooding with new peaks of record at nine continuous-record streamflow-gaging stations. The U.S. Geological Survey (USGS) documented peak streamflows and water-surface elevations at 125 continuous-record streamflow-gaging stations, 27 crest-stage partial-record stations, and peak water-surface elevations at 24 continuous-record tide gages within the State of New Jersey. With rainfall totals averaging more than 10 inches throughout the State, peak-of-record flood elevations and streamflows occurred at 32 continuous-record streamflow-gaging stations. Flood-frequency recurrence-intervals were recomputed for 80 gages with 20 or more years of record; 25 crest-stage gages ranged from 25 years to greater than 500 years for the peak-of-record floods. The maximum peak streamflow per square mile ranged from 20 to 759 cubic feet per second per square mile. The August 27–30, 2011, flood peaks rank as the peaks of record for 32 continuous-record streamflow-gaging stations with a period of record of 23 to 100 years, as the second highest peaks for 21 continuous-record streamflow-gaging stations with a period of record of 21 to 114 years, and the third highest peaks of record for 11 continuous-record streamflow-gaging stations with a period of record of 43 to 96 years. Several gages have documented peaks dating back to 1903. About 1 million people across the State were evacuated, and every county was eventually declared a Federal disaster area. Property damage in New Jersey was estimated to be $1 billion. Governor Chris Christie declared a State of Emergency for New Jersey on August 31, 2011. After assessment of the damage by the Federal Emergency Management Agency, President Obama declared all 21 counties major disaster areas in the State of New Jersey on August 31, 2011.

New Jersey↗
USGS2014

Conceptual model of the uppermost principal aquifer systems in the Williston and Powder River structural basins, United States and Canada

The three uppermost principal aquifer systems of the Northern Great Plains—the glacial, lower Tertiary, and Upper Cretaceous aquifer systems—are described in this report and provide water for irrigation, mining, public and domestic supply, livestock, and industrial uses. These aquifer systems primarily are present in two nationally important fossil-fuelproducing areas: the Williston and Powder River structural basins in the United States and Canada. The glacial aquifer system is contained within glacial deposits that overlie the lower Tertiary and Upper Cretaceous aquifer systems in the northeastern part of the Williston structural basin. Productive sand and gravel aquifers exist within this aquifer system. The Upper Cretaceous aquifer system is contained within bedrock lithostratigraphic units as deep as 2,850 and 8,500 feet below land surface in the Williston and Powder River structural basins, respectively. Petroleum extraction from much deeper formations, such as the Bakken Formation, is rapidly increasing because of recently improved hydraulic fracturing methods that require large volumes of relatively freshwater from shallow aquifers or surface water. Extraction of coalbed natural gas from within the lower Tertiary aquifer system requires removal of large volumes of groundwater to allow degasification. Recognizing the importance of understanding water resources in these energy-rich basins, the U.S. Geological Survey (USGS) Groundwater Resources Program ( http://water.usgs.gov/ogw/gwrp/ ) began a groundwater study of the Williston and Powder River structural basins in 2011 to quantify this groundwater resource, the results of which are described in this report. The overall objective of this study was to characterize, quantify, and provide an improved conceptual understanding of the three uppermost and principal aquifer systems in energy-resource areas of the Northern Great Plains to assist in groundwater-resource management for multiple uses. The study area includes parts of Montana, North Dakota, South Dakota, and Wyoming in the United States and Manitoba and Saskatchewan in Canada. The glacial aquifer system is contained within glacial drift consisting primarily of till, with smaller amounts of glacial outwash sand and gravel deposits. The lower Tertiary and Upper Cretaceous aquifer systems are contained within several formations of the Tertiary and Cretaceous geologic systems, which are hydraulically separated from underlying aquifers by a basal confining unit. The lower Tertiary and Upper Cretaceous aquifer systems each were divided into three hydrogeologic units that correspond to one or more lithostratigraphic units. The period prior to 1960 is defined as the predevelopment period when little groundwater was extracted. From 1960 through 1990, numerous flowing wells were installed near the Yellowstone, Little Missouri and Knife Rivers, resulting in local groundwater declines. Recently developed technologies for the extraction of petroleum resources, which largely have been applied in the study area since about 2005, require millions of gallons of water for construction of each well, with additional water needed for long-term operation; therefore, the potential for an increase in groundwater extraction is high. In this study, groundwater recharge and discharge components were estimated for the period 1981–2005. Groundwater recharge primarily occurs from infiltration of rainfall and snowmelt (precipitation recharge) and infiltration of streams into the ground (stream infiltration). Total estimated recharge to the Williston and Powder River control volumes is 4,560 and 1,500 cubic feet per second, respectively. Estimated precipitation recharge is 26 and 15 percent of total recharge for the Williston and Powder River control volumes, respectively. Estimated stream infiltration is 71 and 80 percent of total recharge for the Williston and Powder River control volumes, respectively. Groundwater discharge primarily is to streams and springs and is estimated to be about 97 and 92 percent of total discharge for the Williston and Powder River control volumes, respectively. Most of the remaining discharge results from pumped and flowing wells. Groundwater flow in the Williston structural basin generally is from the west and southwest toward the east, where discharge to streams occurs. Locally, in the uppermost hydrogeologic units, groundwater generally is unconfined and flows from topographically high to low areas, where discharge to streams occurs. Groundwater flow in the Powder River structural basin generally is toward the north, with local variations, particularly in the upper Fort Union aquifer, where flow is toward streams.

Manitoba;Montana;North Dakota;Saskatchewan;South D↗
USGS2009

Summary of surface-water quality data from the Illinois River Basin in Northeast Oklahoma, 1970-2007

The quality of streams in the Illinois River Basin of northeastern Oklahoma is potentially threatened by increased quantities of wastes discharged from increasing human populations, grazing of about 160,000 cattle, and confined animal feeding operations raising about 20 million chickens. Increasing numbers of humans and livestock in the basin contribute nutrients and bacteria to surface water and groundwater, causing greater than the typical concentrations of those constituents for this region. Consequences of increasing contributions of these substances can include increased algal growth (eutrophication) in streams and lakes; impairment of habitat for native aquatic animals, including desirable game fish species; impairment of drinking-water quality by sediments, turbidity, taste-and-odor causing chemicals, toxic algal compounds, and bacteria; and reduction in the aesthetic quality of the streams. The U.S. Geological Survey, in cooperation with the Oklahoma Scenic Rivers Commission, prepared this report to summarize the surface-water-quality data collected by the U.S. Geological Survey at five long-term surface-water-quality monitoring sites. The data summarized include major ions, nutrients, sediment, and fecal-indicator bacteria from the Illinois River Basin in Oklahoma for 1970 through 2007. General water chemistry, concentrations of nitrogen and phosphorus compounds, chlorophyll-a (an indicator of algal biomass), fecal-indicator bacteria counts, and sediment concentrations were similar among the five long-term monitoring sites in the Illinois River Basin in northeast Oklahoma. Most water samples were phosphorus-limited, meaning that they contained a smaller proportion of phosphorus, relative to nitrogen, than typically occurs in algal tissues. Greater degrees of nitrogen limitation occurred at three of the five sites which were sampled back to the 1970s, probably due to use of detergents containing greater concentrations of phosphorus than in subsequent periods. Concentrations of nitrogen, phosphorus, and sediment, and counts of bacteria generally increased with streamflow at the five sites, probably due to runoff from the land surface and re-suspension of streambed sediments. Phosphorus concentrations typically exceeded the Oklahoma standard of 0.037 milligrams per liter for Scenic Rivers. Concentrations of chlorophyll-a in phytoplankton in water samples collected at the five sites were not well correlated with streamflow, nor to concentrations of the nutrients nitrogen and phosphorus, probably because much of the algae growing in these streams are periphyton attached to streambed cobbles and other debris, rather than phytoplankton in the water column. Sediment concentrations correlated with phosphorus concentrations in water samples collected at the sites, probably due to sorption of phosphorus to soil particles and streambed sediments and runoff of soils and animal wastes at the land surface and resuspension of streambed sediments and phosphorus during wet, high-flow periods. Fecal coliform bacteria counts at the five sites sometimes exceeded the Oklahoma Primary Body Contact Standard of 400 colonies per 100 milliliters when streamflows were greater than 1000 cubic feet per second. Ultimately, Lake Tenkiller, an important ecological and economic resource for the region, receives the compounds that runoff the land surface or seep to local streams from groundwater in the basin. Because of eutrophication from increased nutrient loading, Lake Tenkiller is listed for impairment by diminished dissolved oxygen concentrations, phosphorus, and chlorophyll-a by the State of Oklahoma in evaluation of surface-water quality required by section 303d of the Clean Water Act. Stored phosphorus in soils and streambed and lakebed sediments may continue to provide phosphorus to local streams and lakes for decades to come. Steps are being made to reduce local sources of phosphorus, including upgrades in capacity and effective

Arkansas, Oklahoma↗
USGS1983

Reconnaissance geology of the Thaniyah Quadrangle, sheet 20/42 C, Kingdom of Saudi Arabia

The Thaniyah quadrangle, sheet 20/42 C, is located in the transition zone between the Hijaz Mountains and the Najd Plateau of southwestern Saudi Arabia between lat 20?00' and 20?30' N., long 42?00' to 42?30' E. The quadrangle is underlain by Precambrian metavolcanic, metasedimentary, plutonic, and dike rocks. Metavolcanic rocks consist of metamorphosed basalt and andesite with minor dacite and rhyolite and underlie three discontinuous northwest-trending belts. Metasedimentary rocks are confined to small areas underlain by quartzite, metasandstone, marble, and calc-silicate rock. Plutonic rocks include an extensive unit of tonalite and quartz diorite and a smaller unit of diorite and quartz diorite, which occupy much of the central part of the quadrangle. A small body of diorite and gabbro and a two-part zone of tonalite gneiss are also present. All of these plutonic rocks are assigned to the An Nimas batholith. Younger plutonic rocks include extensive graphic granite and rhyolite in the northeastern part of the quadrangle and several smaller bodies of granitic rocks and of gabbro. The metavolcanic rocks commonly have strong foliation with northwest strike and steep to vertical dip. Diorite and quartz diorite are sheared and brecciated and apparently syntectonic. Tonalite and quartz diorite are both foliate and nonfoliate and were intruded in episodes both preceding and following shearing. The granitic rocks and gabbro are post-tectonic. Trends of faults and dikes are mostly related to the Najd faulting episode. Radiometric ages, mostly from adjacent quadrangles, suggest that the An Nimas batholith is 835 to 800 Ma, gabbro and granite, except the graphic granite and rhyolite unit, are about 640 to 615 Ma, and the graphic granite and rhyolite 575 to 565 Ma old. Metavolcanic rocks similar to those hosting copper and gold mineralization in the Wadi Shuwas mining district adjacent to the southwestern part of the quadrangle are abundant. An ancient copper mine was discovered at the edge of the tonalite gneiss belt east of Wadi Ranyah. Granite and gabbro have economic potential as building stone.

Open-File Report↗
USGS2013

Geologic map of the Harvard Lakes 7.5' quadrangle, Park and Chaffee Counties, Colorado

The Harvard Lakes 1:24,000-scale quadrangle spans the Arkansas River Valley in central Colorado, and includes the foothills of the Sawatch Range on the west and Mosquito Range on the east. The Arkansas River valley lies in the northern end of the Rio Grande rift and is structurally controlled by Oligocene and younger normal faults mostly along the west side of the valley. Five separate pediment surfaces were mapped, and distinctions were made between terraces formed by the Arkansas River and surfaces that formed from erosion and alluviation that emanated from the Sawatch Range. Three flood deposits containing boulders as long as 15 m were deposited from glacial breakouts just north of the quadrangle. Miocene and Pliocene basin-fill deposits of the Dry Union Formation are exposed beneath terrace or pediment deposits in several places. The southwestern part of the late Eocene Buffalo Peaks volcanic center, mostly andesitic breccias and flows and ash-flow tuffs, occupy the northeastern corner of the map. Dated Tertiary intrusive rocks include Late Cretaceous or early Paleocene hornblende gabbro and hornblende monzonite. Numerous rhyolite and dacite dikes of inferred early Tertiary or Late Cretaceous age also intrude the basement rocks. Basement rocks are predominantly Mesoproterozoic granites, and subordinately Paleoproterozoic biotite gneiss and granitic gneiss.

Colorado↗
USGS1996

Simulation of water quality for Salt Creek in northeastern Illinois

Water-quality processes in the Salt Creek watershed in northeastern Illinois were simulated with a computer model. Selected waste-load scenarios for 7-day, 10-year low-flow conditions were simulated in the stream system. The model development involved the calibration of the U.S. Environmental Protection Agency QUAL2E model to water-quality constituent concentration data collected by the Illinois Environmental Protection Agency (IEPA) for a diel survey on August 29-30, 1995, and the verification of this model with water-quality constituent concentration data collected by the IEPA for a diel survey on June 27-28, 1995. In-stream measurements of sediment oxygen demand rates and carbonaceous biochemical oxygen demand (CBOD) decay rates by the IEPA and traveltime and reaeration-rate coefficients by the U.S. Geological Survey facilitated the development of a model for simulation of water quality in the Salt Creek watershed. In general, the verification of the calibrated model increased confidence in the utility of the model for water-quality planning in the Salt Creek watershed. However, the model was adjusted to better simulate constituent concentrations measured during the June 27-28, 1995, diel survey. Two versions of the QUAL2E model were utilized to simulate dissolved oxygen (DO) concentrations in the Salt Creek watershed for selected effluent discharge and concentration scenarios for water-quality planning: (1) the QUAL2E model calibrated to the August 29-30, 1995, diel survey, and (2) the QUAL2E model adjusted to the June 27-28, 1995, diel survey. The results of these simulations indicated that the QUAL2E model adjusted to the June 27-28, 1995, diel survey simulates reliable information for water-quality planning. The results of these simulations also indicated that to maintain DO concentrations greater than 5 milligrams per liter (mg/L) throughout most of Salt Creek for 7-day, 10-year low-flow conditions, the sewage-treatment plants (STP's) must discharge effluent with CBOD and total ammonia as nitrogen concentrations substantially below the permit limits. If the STP's discharge effluent with CBOD and total ammonia as nitrogen concentrations at the permit limits for 7-day, 10-year low-flow conditions, DO concentrations less than 5 mg/L are expected for all of Salt Creek downstream from Fullerton Avenue (river mile 23.1).

Open-File Report↗
USGS2021

Assessment of water availability in the Osage Nation using an integrated hydrologic-flow model

The Osage Nation of northeastern Oklahoma, conterminous with Osage County, covers about 2,900 square miles. The area is primarily rural with 62 percent of the land being native prairie grass, and much of the area is used for cattle ranching and extraction of petroleum and natural gas. Protection of water rights are important to the Osage Nation because of its reliance on cattle ranching and the potential for impairment of water quality by petroleum extraction. Additionally, the potential for future population increases, demands for water from neighboring areas such as the Tulsa metropolitan area, and expansion of petroleum and natural-gas extraction on water resources of this area further the need for the Osage Nation to better understand its water availability. Therefore, the U.S. Geological Survey, in cooperation with the Osage Nation, completed a hydrologic investigation to assess the status and availability of surface-water and groundwater resources in the Osage Nation. A transient integrated hydrologic-flow model was constructed using the U.S. Geological Survey fully integrated hydrologic-flow model called the MODFLOW One-Water Hydrologic Model. The integrated hydrologic-flow model, called the Osage Nation Integrated Hydrologic Model (ONIHM), was constructed and uses an orthogonal grid of 276 rows and 289 columns, and each grid cell measures 1,312.34 feet (ft; 400 meters) per side, with eight variably thick vertical layers that represented the alluvial and bedrock aquifers within the study area, including the alluvial aquifer, the Vamoosa-Ada aquifer, and the minor Pennsylvanian bedrock aquifers, and the confining units. Landscape and groundwater-flow processes were simulated for two periods: (1) the 1950–2014 period from January 1950 through September 2014 and (2) the forecast period from October 2014 through December 2099. The 1950–2014 period ONIHM simulated past conditions using measured or estimated inputs, and the forecast-period ONIHM simulated three separate potential forecast conditions under constant dry, average, or wet climate conditions using calibrated input values from the 1950–2014 period ONIHM. The 1950–2014 period ONIHM was calibrated by linking the Parameter Estimation software (PEST) with the MODFLOW One-Water Hydrologic Model. PEST uses statistical parameter estimation techniques to identify the best set of parameter values to minimize the difference between measured or estimated calibration targets and their simulated equivalent values (residuals). Tikhonov regularization and singular-value decomposition-assist features of PEST were used during the calibration process. The 1950–2014 period ONIHM was calibrated to 713 measured groundwater levels at 195 wells; 95,636 estimated monthly mean groundwater levels at 124 wells; 5,307 measured streamflows at 13 streamgages; and 8,679 simulated mean monthly streamflows at 10 streamgages extracted from a surface-water model by adjusting 231 parameters. The estimated groundwater-level observations and streamflows were included as observations to improve the spatial and temporal density of observation targets during calibration. The best set of parameter values obtained during the calibration process of the 1950–2014 model was then used as the input parameter values for the forecast model simulations. A comparison of the calibration targets to their corresponding simulated values indicated that the model adequately reproduced streamflows and groundwater levels for some streamgages and wells and underestimated streamflows and groundwater levels at other locations. Measured and simulated streamflows correlated adequately with a coefficient of determination of 0.938, as did water levels with a coefficient of determination of 0.795. The 1950–2014 period ONIHM underestimated certain groundwater levels and streamflows, but generally measured or estimated calibration targets correlated well with simulated equivalents, which indicated that the model can adequately simulate the response of the hydrologic system to stresses in the 1950–2014 and forecast periods. In the 1950–2014 period ONIHM, the calibrated mean horizontal hydraulic conductivity for layer 1 alluvial aquifer was 30.7 feet per day, and the seven lower layers had a calibrated mean horizontal hydraulic conductivity of less than 3.3 feet per day. The mean calibrated groundwater-level residual was 16.6 ft, and the mean calibrated streamflow residual of the Arkansas River at Ralston, Oklahoma, streamgage (U.S. Geological Survey station 07152500) was within 6 percent (373 cubic feet per second) of mean measured streamflow for the 1950–2014 period ONIHM. The ONIHM simulated landscape fluxes of precipitation; groundwater applied by irrigation wells; evapotranspiration from precipitation, groundwater, and irrigation; runoff from precipitation; and deep percolation from precipitation. The largest loss of water from the landscape was evapotranspiration from precipitation with a calibrated mean annual outflow of 32 inches (in.): mean annual precipitation was about 36 in. Calibrated mean annual runoff and deep percolation (recharge to the water table) rates were 4.7 inches per year (in/yr) and 0.70 in/yr, respectively, for the 1950–2014 period ONIHM. The calibrated 1950–2014 period ONIHM groundwater fluxes included net farm net recharge (calculated as the difference between the inflow of recharge to the water table and the outflow of evapotranspiration from the water table such that negative values indicate that evapotranspiration from the water table was greater than deep percolation [recharge to the water table] and vice versa). Net farm net recharge was the largest flux from the groundwater system with a mean annual net outflow of 153.4 cubic feet per second. Stream leakage was the largest flux to the groundwater system with a mean annual net inflow of 152.5 cubic feet per second, indicating that, on average, the groundwater/surface-water interaction was a “losing” system where stream water leaked into the subsurface and recharged the water table. Simulated monthly trends demonstrated that net stream leakage was the largest inflow to the groundwater-flow system for 10 of the 12 months; for the other 2 months (January and March), farm net recharge (January) and net storage (March) were the largest inflow to the groundwater-flow system. A saline groundwater interface map was created for the study and compared to the water levels from the final stress period of the 1950–2014 model to identify the presence of fresh/marginal groundwater throughout the study area. Fresh/marginal groundwater was characterized as groundwater with less than 1,500 milligrams per liter of total dissolved solids. Fresh/marginal groundwater thickness ranged from 0 to 438.2 ft within the study area. The thickest regions of fresh/marginal groundwater were in the eastern part of the study area near Sand Creek, Bird Creek, and Hominy Creek and in the Arkansas River alluvial aquifer in the region downstream from the Arkansas River at Ralston, Okla. Like the 1950–2014 model, forecast model results for the landscape indicated that transpiration from precipitation was the largest flux out of the landscape for all three forecasts, constituting 77, 73, and 58 percent of precipitation for the dry, average, and wet forecasts, respectively. The dry and average forecast landscape fluxes demonstrated similar trends and magnitudes, whereas the wet forecast landscape fluxes indicated the largest changes compared to the average forecast fluxes. Most notably, runoff increased from a mean of 1.1 and 1.6 in/yr for the dry and average forecasts, respectively, to 10 in/yr for the wet forecast. Similar changes occurred for the other wet forecast landscape fluxes. The calibrated 1950–2014 period ONIHM simulated three forecasts to assess the effects of potential climatic changes on the hydrologic system from October 2014 to December 2099. The three forecasts simulated theoretical dry, average, and wet conditions using precipitation and potential evapotranspiration datasets from selected years in the calibrated 1950–2014 period ONIHM. Annual precipitation amounts were 26.89, 35.47, and 50.73 in. for the dry, average, and wet forecasts, respectively. Groundwater-flow component forecast results indicated that stream leakage is always a net inflow to the groundwater-flow system for dry, average, and wet conditions, meaning the study area stream network is always predominantly a “losing” regime where stream water infiltrates into the underlying aquifer. Storage was only a net outflow from the groundwater-flow system and indicated a replenishment to groundwater storage that resulted in an increase in groundwater levels only during the wet forecast. Further, these gains in groundwater storage for the wet forecast occurred only during February through June. Mean fresh/marginal groundwater saturated thicknesses were 125 and 126 ft for the dry and average forecast conditions, respectively, and wet forecast average thickness was 145 ft and ranged from 0 to 443 ft. The spatial extents of fresh/marginal groundwater at the end of the dry, average, and wet forecast model periods (December 2099) did not change substantially from the end of the 1950–2014 model period (September 2014).

Kansas, Oklahoma↗
USGS2008

Association among active seafloor deformation, mound formation, and gas hydrate growth and accumulation within the seafloor of the Santa Monica Basin, offshore California

Seafloor blister-like mounds, methane migration and gas hydrate formation were investigated through detailed seafloor surveys in Santa Monica Basin, offshore of Los Angeles, California. Two distinct deep-water (??? 800??m water depth) topographic mounds were surveyed using an autonomous underwater vehicle (carrying a multibeam sonar and a chirp sub-bottom profiler) and one of these was explored with the remotely operated vehicle Tiburon. The mounds are > 10??m high and > 100??m wide dome-shaped bathymetric features. These mounds protrude from crests of broad anticlines (~ 20??m high and 1 to 3??km long) formed within latest Quaternary-aged seafloor sediment associated with compression between lateral offsets in regional faults. No allochthonous sediments were observed on the mounds, except slumped material off the steep slopes of the mounds. Continuous streams of methane gas bubbles emanate from the crest of the northeastern mound, and extensive methane-derived authigenic carbonate pavements and chemosynthetic communities mantle the mound surface. The large local vertical displacements needed to produce these mounds suggests a corresponding net mass accumulation has occurred within the immediate subsurface. Formation and accumulation of pure gas hydrate lenses in the subsurface is proposed as a mechanism to blister the seafloor and form these mounds. ?? 2008 Elsevier B.V. All rights reserved.

Marine Geology↗
USGS2008

Geologic Map of the Meskhent Tessera Quadrangle (V-3), Venus

The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the Venusian atmosphere on October 12, 1994. Magellan Mission objectives included (1) improving the knowledge of the geological processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving the knowledge of the geophysics of Venus by analysis of Venusian gravity. The Meskhent Tessera quadrangle is in the northern hemisphere of Venus and extends from lat 50 degrees to 75 degrees N. and from long 60 degrees to 120 degrees E. In regional context, the Meskhent Tessera quadrangle is surrounded by extensive tessera regions to the west (Fortuna and Laima Tesserae) and to the south (Tellus Tessera) and by a large basinlike lowland (Atalanta Planitia) on the east. The northern third of the quadrangle covers the easternmost portion of the large topographic province of Ishtar Terra (northwestern map area) and the more localized upland of Tethus Regio (northeastern map area).

Scientific Investigations Map↗
USGS2024

Groundwater hydrology, groundwater and surface-water interactions, aquifer testing, and groundwater-flow simulations for the Fountain Creek alluvial aquifer, near Colorado Springs, Colorado, 2018–20

From 2018 through 2020, the U.S. Geological Survey, in cooperation with the Air Force Civil Engineering Center, conducted an integrated study of the Fountain Creek alluvial aquifer located near Colorado Springs, Colorado. The objective of the study was to characterize hydrologic conditions for the alluvial aquifer pertinent to the potential for transport of solutes. Specific goals of this report were to characterize the groundwater hydrology of the area, to quantify groundwater and surface-water interactions, to estimate hydraulic properties of the aquifer using aquifer testing, and to complete numerical simulations of groundwater flow. Synoptic groundwater-level elevation measurements completed throughout this study, and as part of other U.S. Geological Survey programs between 1994 and 2020, indicate groundwater-level elevations fluctuate on annual and interannual timeframes. Groundwater-level fluctuations likely were caused by temporally variable groundwater recharge and discharge components in the area, with many wells showing maximum groundwater-level elevations during the winter months (November through March). From an interannual perspective, groundwater-level fluctuations appear to have reached maximum values during 2000 to 2003, decreased during 2003 to 2006, and remained relatively constant since that time, with the exception of several wells which have displayed rising groundwater-level elevations since 2018. Spatial evaluation of groundwater-level elevations indicates groundwater flow is generally from northeast to southwest within the vicinity of several alluvial paleochannels occurring along the northeastern margin of the aquifer. Within the center of the aquifer along Fountain Creek, groundwater flow is generally from north to south, approximately paralleling surface-water flow. To quantitatively understand the potential effect of groundwater recharge and groundwater pumping on fluctuations in groundwater-level elevation, a statistical transfer-function-noise model was applied. Results of the statistical model indicate throughout most of the aquifer, fluctuations were primarily the result of recharge seasonality. In the main stem of the aquifer where groundwater pumping wells were more concentrated, however, groundwater-level elevation fluctuations were also attributable to groundwater pumping through time. Three-dimensional evaluation of the aquifer geometry near Fountain Creek was combined with synoptic streamflow measurement and accounting of stream gains and losses to evaluate groundwater and surface-water interactions in the study area. Streamflow gain or loss calculations indicate Fountain Creek both gains from and loses flow to the alluvial aquifer, and gaining or losing reaches of the stream may be partially controlled by the depth to bedrock near the stream. Reaches with streamflow gains tend to coincide with areas where the estimated depth to bedrock is decreasing, meaning the alluvial aquifer is likely thinning in these areas and groundwater-flow paths may be converging and discharging groundwater to the stream. Losing reaches tended to coincide with locally greater depth to bedrock where the alluvial aquifer is likely thicker and has greater storage potential for surface water lost from Fountain Creek. Results of aquifer testing indicate hydraulic conductivity, estimated from slug tests and single-well pumping tests, ranged from 0.32 to 1,410 feet per day (ft/d) and 4.13 to 664 ft/d, respectively. These results are similar to the range of values from previous aquifer tests in the study area. Hydraulic conductivities from aquifer testing for this study were generally greater than the estimates of previous slug tests and had a mean value less than the estimates from previous pumping tests. Spatial evaluation of aquifer testing results indicates hydraulic conductivity tends to be greater in the main stem of the alluvial aquifer and lower in paleochannels upgradient from the main stem of the aquifer. The spatial variation in hydraulic conductivity may be attributed to the geomorphologic processes that formed the alluvial aquifer. Compacted sediment in the paleochannels has not been potentially transported sufficient distance to cause grain-size sorting, resulting in a poorly sorted deposit and lower hydraulic conductivities. In the central portion of the alluvial aquifer, near Fountain Creek, the sediments have been transported farther from their source areas and are likely better sorted, removing finer grained sediments that would cause lower hydraulic conductivity. A numerical groundwater-flow model was calibrated for the Fountain Creek alluvial aquifer for 2000–19 to simulate water-budget components, groundwater-flow directions, and groundwater-flow paths. The model simulated precipitation recharge, groundwater and surface-water interactions, evapotranspiration, high-volume groundwater pumping by pumping wells, and external inflows and outflows occurring along the boundaries of the alluvial aquifer. Model calibration was completed using manual and automated approaches, the latter of which assisted in quantifying model results sensitivity to input parameters. The calibrated model corresponds well with groundwater-level elevation observations, with a mean residual (observed minus simulated groundwater-level elevation) equal to −0.60 feet. Simulated groundwater base flow to streams was typically within 10 percent of base flow estimated by independent methods. Groundwater and surface-water interactions represented the largest water-budget components of the aquifer, with the second largest groundwater discharge component coming from pumping wells. Groundwater and surface-water interactions represent both the largest gain and loss terms in the water budget, because these interactions differ spatially, meaning in some areas of the model domain groundwater is being recharged by streams, whereas in other areas, groundwater is discharged to streams. Estimates of advective groundwater-flow paths indicate pumping wells may capture groundwater recharged from losing streams and groundwater that flows into the main stem of the alluvial aquifer from paleochannels.

Colorado↗
USGS2018

History and dynamics of the Greater Yellowstone Glacial System during the last two glaciations

The Greater Yellowstone Glacial System (GYGS) covered about 20,000 km2 at its maximum Pleistocene extent. The initiation, culmination, and ultimate decay of the GYGS involved complex interactions between several coalescent ice masses flowing from glacial source areas adjoining and including the Yellowstone Plateau. Here, we present an updated review of the history and dynamics of the GYGS during the penultimate (Bull Lake) and last (Pinedale) glaciations, drawing upon an integration of glacial-geologic mapping with >130 cosmogenic 10Be and 3He exposure ages. Bull Lake glacial deposits in greater Yellowstone are dated to ca. 150–140 ka and correlate with marine isotope stage 6. The Bull Lake glaciation extended well beyond the Pinedale along the southern and western GYGS margins, but Pinedale glaciers overrode Bull Lake ice limits on the north and east sides. The northeastward shift of the center of ice mass from Bull Lake to Pinedale time may be explained by uplift on the leading edge of the Yellowstone hotspot and subsidence on the trailing margin. In early Pinedale time (∼22–18 ka), ice buildup culminated in the high terrain of the Beartooth Uplift and High Absaroka Range. Glaciers from these source regions flowed onto the northeastern margin of the Yellowstone Plateau and advanced to terminal moraines beyond Clarks Fork Canyon and in Jackson Hole. By middle Pinedale time (∼18–16 ka), the Yellowstone Plateau ice cap surface had risen above the equilibrium-line altitude, stimulating orographic glacial buildup nourished by storms funneled eastward through the Snake River Plain. The plateau ice cap eventually thickened to >1000 m and joined glaciers from the Beartooth Uplift and Gallatin Range to form the northern Yellowstone outlet glacier. Terrain east and downwind of the ice cap crest was placed in a precipitation shadow, resulting in glacial recession in these regions. During the late Pinedale (∼16–13 ka), the plateau ice cap prograded southwestward toward the direction of moisture supply, leading to advances along the southern and western margins of the GYGS. Northern sectors of the plateau ice cap were nearly stagnant at this time. The Yellowstone region experienced widespread deglaciation ca. 15–14 ka in response to warming climate. Unloading of the ∼1 km-thick plateau ice cap and consequent release of pressure on the magmatic system beneath Yellowstone was not accompanied by volcanism, indicating that the magma chamber was not primed to erupt via decompression during the last deglaciation.

Idaho, Montana Wyoming↗
USGS2004

Spatial and temporal variation of Cenozoic surface elevation in the Great Basin and Sierra Nevada

The surface uplift of mountain belts caused by tectonism plays an important role in determining the long-term climate evolution of the Earth. However, the general lack of information on the paleotopography of mountain belts limits our ability to identify the links and feedbacks between topography, tectonics, and climate change on geologic time-scales. Here, we present a δ 18 O and δD record of authigenic minerals for the northern Great Basin that captures the timing and magnitude of regional surface uplift and subsidence events in the western United States during the Cenozoic. Authigenic calcite, smectite, and chert δ 18 O values suggest the northern Great Basin region experienced ~2km of surface uplift between the middle Eocene and early Oligocene followed by ~1 to 2km of surface subsidence in the southern Great Basin and/or Sierra Nevada since the middle Miocene. These data when combined with previously published work show that the surface uplift history varied in both space and time. Surface uplift migrated from north to south with high elevations in southern British Columbia and northeastern Washington in the middle Eocene and development of surface uplift in north and central Nevada in the Oligocene. This pattern of north to south surface uplift is similar to the timing of magmatism in the western Cordillera, a result that supports tectonic models linking magamtism with removal of mantle lithosphere and/or a subducting slab.

California, Idaho, Nevada, Oregon, Utah↗
USGS1985

Management of ground water and evolving hydrogeologic studies in New Jersey : a heavily urbanized and industrialized state in the northeastern United States

New Jersey is the most densely populated and one of the most industrialized states in the United States. An abundance of freshwater and proximity to major northeastern metropolitan centers has facilitated this development. Pumpage of freshwater from all aquifers in the State in 1980 was 730 million gallons per day (2.76 million cubic meters per day). Management and efficient development of the ground-water resources of the State are the responsibility of the New Jersey Department of Environmental Protection. Laws have been enacted and updated by the State legislature to manage water allocation and to control the disposal of hazardous wastes. Present resource management is guided by the New Jersey Water-Supply Master Plan of 1981. Funding for management activities is partially derived from the sale of state-approved bonds. Effective planning and regional management require accurate and up-to-date hydrologic information and analyses. The U.S. Geological Survey, in cooperation with the New Jersey Geological Survey, is conducting three intensive ground-water studies involving the collection and interpretation of hydrologic data to meet the urgent water-management needs of New Jersey. These studies are part of a long-term cooperative program and are funded through the Water-Supply Bond Act of 1981. They began in 1983 and are scheduled to be completed in 1988. The project areas are situated in the New Jersey part of the Atlantic Coastal Plain in and near Atlantic City, Camden, and South River. They range in size from 400 to 1,200 mil (1,040 to 3,120 km2). The studies are designed to define the geology, hydrology, and geochemistry of the local ground-water systems. The results of these studies will enable the State to address more effectively major problems in these areas such as declining water levels, overpumping, saltwater intrusion, and ground-water contamination resulting from the improper disposal of hazardous wastes. Specific objectives of these studies by the U.S. Geological Survey are to (1) develop an accurate and up-to-date hydrogeologic data base, (2) design and implement a data-collection program and establish a computerized information management system, (3) refine the conceptualization of the ground-water flow system, and (4) define the geochemistry of the aquifer system by conducting a water-quality appraisal. The objectives are accomplished by standard hydrogeologic methods. Information concerning hydrogeologic framework, ground-water levels, water use, hydraulic characteristics, and water quality in the study areas is compiled from all available sources. Additional data needed are collected through well inventories, surface geophysical surveys, water-quality samplings, water-level measurements, and a well-drilling program. Interpretation of the flow system is based on the use of standard analytical techniques and digital flow modeling. Calibrated flow models will provide ground-water managers with a mechanism to develop and test regional water-supply strategies. Definition of the geochemistry of the aquifer system is accomplished through a variety of methods which depend on the problems and available data in the particular study area. The approach includes statistical analysis of water-quality data, reaction-path modeling, and determination of the movement of chemical constituents using analytical and numerical modeling techniques. A combined staff of 25 to 30 professionals and technicians from the New Jersey District office of the U.S. Geological Survey is committed to the three studies. The staff has specialists in geohydrology, numerical modeling, geochemistry, geophysics, and computer science. The findings of these studies will be published in data reports, interpretive reports, instructional manuals and journal articles.

New Jersey↗
USGS2010

Quantifying effects of climate change on the snowmelt-dominated groundwater resources of northern New England

Recent U.S. Geological Survey (USGS) climate studies in New England have shown substantial evidence of hydrologic changes during the last 100 years, including trends toward earlier snowmelt runoff, decreasing occurrence of river ice, and decreasing winter snowpack. These studies are being expanded to include investigation of trends in groundwater levels and fluctuations. Groundwater is an important drinking-water source throughout northern New England (Maine, New Hampshire, and Vermont). The USGS is currently investigating whether or not groundwater recharge from snowmelt and precipitation exhibits historical trends. In addition to trend-testing, groundwater resources also will be analyzed by relating groundwater-level changes to the large year-to-year variability in weather conditions. Introduction The USGS has documented many seasonal climate-related changes in the northeastern United States that have occurred during the last 30 to 150 years. These changes include earlier snowmelt runoff in the late winter and early spring, decreasing duration of ice on rivers and lakes, decreasing ratio of snowfall to total precipitation, and denser and thinner late-winter snowpack. All of these changes are consistent with warming winter and spring air temperatures (Dudley and Hodgkins, 2002; Hodgkins and others, 2002; Huntington and others, 2004; Hodgkins and others, 2005; Hodgkins and Dudley, 2006a; Hodgkins and Dudley, 2006b). Climate-model projections for the Northeast indicate air-temperature warming, earlier snowmelt runoff, increases in annual evaporation, and decreased low streamflows (Hayhoe and others, 2007). The contribution and timing of spring snowmelt to groundwater recharge is particularly important to groundwater resources in the northeastern United States where aquifers typically consist of thin sediments overlying crystalline bedrock with relatively little storage capacity (Mack, 2009). Following spring recharge, groundwater slowly flows into streams throughout the summer. This groundwater flow is a source of cool water during the summer and accounts for a large proportion of the streamflow during summer low-flow periods. Groundwater is an important drinking-water source in northern New England. Approximately 32 percent of public water suppliers draw water from groundwater sources in Vermont, New Hampshire, and Maine, and approximately 40 percent of the population derives its drinking water from private wells (Kenny and others, 2009). It is vital to understand changes that may be occurring to such an important resource for planning industrial and agricultural water uses and protecting drinking water.

Fact Sheet↗
USGS2001

Reconnaissance for trace metals in bed sediment, Wright Patman Lake, near Texarkana, Texas

Many contaminants can be introduced into the environment by urban and industrial activities. The drainage area of Wright Patman Lake is influenced by these activities. Among the contaminants associated with urban and industrial activities are trace metals such as arsenic, lead, mercury, and zinc. These contaminants are relatively insoluble in water and commonly are found in stream, lake, and reservoir bottom sediment, especially the clays and silts within the sediment. Wright Patman Lake serves as the major potable water supply for the city of Texarkana and surrounding communities. Texarkana, located in the northeastern corner of Texas and the southwestern corner of Arkansas, had a population of about 56,000 in 1998, which reflects an increase of about 3.4 percent from the 1990 census (Ramos, 1999). Texarkana Water Utilities, which manages the water-treatment facilities for Texarkana, proposes to dredge the lake bed near the water intake in the Elliot Creek arm of Wright Patman Lake. It is possible that arsenic, lead, mercury, and other trace metals might be released into the water if the bed sediment is disturbed. Bed sediment in the Elliot Creek arm of the lake, in particular, could contain trace metals because of its proximity to Red River Army Depot and because industrial land use is prevalent in the headwaters of Elliot Creek. The U.S. Geological Survey (USGS), in cooperation with Reconnaissance for Trace Metals in Bed Sediment, Wright Patman Lake, Near Texarkana, Texas In cooperation with the Texarkana Water Utilities conducted a reconnaissance of Wright Patman Lake to collect bed-sediment samples for analysis of trace metals. This report presents trace metal concentrations in bed-sediment samples collected at six sites along the Elliot Creek arm of the lake, one site each in two adjacent arms, and one site near the dam on June 16, 1999 (fig. 1). One bed-sediment sample was collected at each of the nine sites, and one sediment core was collected at each of two of the sites. Trace metal concentrations are compared to sediment-quality guidelines for the protection of aquatic life and to screening levels based on historical trace metal concentrations in bed sediment of Texas reservoirs.

Texas↗