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At least 1,441 records · Page 80Linked to original sources

USGS1991

Oxygen, hydrogen, and sulfur isotope studies in the Juneau gold belt, southeastern Alaska: Constraints on the origin of hydrothermal fluids

The delta 18 O values of gold-bearing quartz from the Juneau gold belt range from 15.2 to 20.8 per mil, indicating that ore fluid values ranged from 7.2 to 12.8 per mil at an estimated temperature of 300 degrees C. Hydrothermal micas from many of the deposits are characterized by delta D values of -75 to -53 per mil, and ore fluids were calculated to have values of -35 to -15 per mil. In contrast, extracted fluid inclusion waters have a broad range of delta D values, from -48 in relatively undeformed quartz to about -110 per mil for some of the more deformed quartz veins. This range of more than 60 per mil reflects various mixtures from inclusions containing isotopically heavy, primary ore fluids and those containing low-temperature, isotopically light meteoric waters that were trapped in late fractures during uplift of the veins to shallow crustal levels. These results indicate a deep crustal source for the ore fluids, most likely of metamorphic origin. Values of delta D for muscovite, biotite, and hornblende from country rocks, as well as of delta 18 O for quartz-feldspar and quartz-plagioclase, provide little evidence of deep circulation of meteoric water along the length of the gold belt.The provinciality of delta 34 data suggests a regional metamorphic fluid of approximately -6 per mil that acquired much of its sulfur from lithologies near sites of ore deposition. Sulfur ratios of sulfide minerals from auriferous quartz range from -17.8 to -5.6 per mil in black phyllite hosts, from -6.0 to -1.3 per mil in less reduced metasedimentary rocks, and from -3.8 to +1.2 per mil in relatively oxidized igneous rocks. The regional fluid is interpreted to have driven desulfidation reactions in relatively 34 S-depleted sulfur reservoirs in the phyllites and 34 S-enriched reservoirs in the more oxidized lithologies.

Economic Geology↗

USGS2007

Groundwater chemistry and occurrence of arsenic in the Meghna floodplain aquifer, southeastern Bangladesh

Dissolved major ions and important heavy metals including total arsenic and iron were measured in groundwater from shallow (25-33 m) and deep (191-318 m) tube-wells in southeastern Bangladesh. These analyses are intended to help describe geochemical processes active in the aquifers and the source and release mechanism of arsenic in sediments for the Meghna Floodplain aquifer. The elevated Cl- and higher proportions of Na+ relative to Ca2+, Mg2+, and K+ in groundwater suggest the influence by a source of Na+ and Cl-. Use of chemical fertilizers may cause higher concentrations of NH 4+ and PO 43- in shallow well samples. In general, most ions are positively correlated with Cl-, with Na+ showing an especially strong correlation with Cl-, indicating that these ions are derived from the same source of saline waters. The relationship between Cl-/HCO 3- ratios and Cl- also shows mixing of fresh groundwater and seawater. Concentrations of dissolved HCO 3- reflect the degree of water-rock interaction in groundwater systems and integrated microbial degradation of organic matter. Mn and Fe-oxyhydroxides are prominent in the clayey subsurface sediment and well known to be strong adsorbents of heavy metals including arsenic. All five shallow well samples had high arsenic concentration that exceeded WHO recommended limit for drinking water. Very low concentrations of SO 42- and NO 3- and high concentrations of dissolved Fe and PO 43- and NH 4+ ions support the reducing condition of subsurface aquifer. Arsenic concentrations demonstrate negative co-relation with the concentrations of SO 42- and NO 3- but correlate weakly with Mo, Fe concentrations and positively with those of P, PO 43- and NH 4+ ions. ?? 2007 Springer-Verlag.

Environmental Geology↗

USGS2005

New York Water-Use Program and data, 2000

The U.S. Geological Survey (USGS) has been publishing estimates of water use every five years since 1950 in the Estimated use of water in the United States circular series. In 1978, the Congress expanded the water-use activities of the USGS by establishing the National Water-Use Information Program (NWUIP). The water-use program in New York is part of the NWUIP and is based on a cooperative agreement between the USGS and the New York State Department of Environmental Conservation (NYSDEC). Together, the NYSDEC and USGS collect, compile, and store water-use data to provide a data base that is useful for water-resources management. The New York State Department of Health (NYSDOH) collects a wide variety of data elements relating to public-water supplies such as the name and location of the suppliers and the amount of water withdrawn. This valuable information is provided to the water-use program. The information summarized in this fact sheet has been published in U.S. Geological Survey Circular 1268, Estimated use of water in the United States in 2000 which can be accessed at http://water.usgs.gov/watuse . The 2000 data (by county) as well as previous years data can also be found at that site. Water withdrawal refers to the removal of water from the ground or its diversion from a surface-water source for use. Withdrawals of fresh and saline surface water and fresh ground water during 2000 were included in this study. The categories considered in this data compilation are public-water supply; deliveries to domestic from public-water suppliers and domestic self-supplied; industrial; thermoelectric-power generation; and irrigation. Saline withdrawals were included for the categories of industrial, mining, and thermoelectric-power generation. Saline water is a significant percentage of total withdrawals for the category of thermoelectric-power generation. The categories of withdrawal for which data were compiled for the 2000 calendar year do not include some of the categories that were addressed in 1995 and published in USGS Circular 1200, Estimated use of water in the United States in 1995. For the 2000 compilation, emphasis was placed on ensuring the quality of data that were collected, rather than attempting to address all categories and data elements on a national scale. Categories that were included in 1995 but not in 2000 are commercial; livestock; mining; the non-withdrawal categories of hydroelectric-power generation, wastewater treatment and public-water supply deliveries to commercial and industrial users. Any comparison made between 1995 and 2000 data need to be made with these category differences in mind. In 1995, the categories of commercial, livestock, and mining were about 280 Mgal/d (million gallons per day) of freshwater and 2.7 percent of total freshwater withdrawals. In addition, the report, New York water-use program and data, 1995, U. S. Geological Survey Fact Sheet 014-02, concentrated on freshwater and did not include saline-surface water withdrawals in the figures. Any comparison between the 1995 and 2000 figures need to be made with this in mind. In 2000, about 12,100 Mgal/d (million gallons per day) of fresh surface and ground water and saline surface water were withdrawn from New York's rivers, streams, lakes, estuaries, bays, and aquifers for the categories addressed. Freshwater withdrawals comprised about 7,080 Mgal/d of this total. With a total population of 18,980,000 people in New York State, the total freshwater withdrawals represent an average of more than 370 gal/d (gallons per day) per capita. The amounts of fresh surface water, ground water, saline surface water, and total amounts of water withdrawn by categories of water use in New York during 2000 are shown. Many of New York's large population centers have developed along major rivers and lakes; as a result, more than 87 percent of the freshwater withdrawals in 2000 were from surface-water bodies (6,190 Mgal/d). More than 65 percent of fresh surface-water withdrawals were for thermoelectric-power generation, and about 32 percent were by public-water suppliers. Of the 890 Mgal/d of ground water withdrawn in 2000 statewide, 65 percent was withdrawn by public-water suppliers, and about 16 percent each by industrial and domestic users. More freshwater is withdrawn by thermoelectric plants than for any other water-use category. Of the freshwater withdrawals within New York, about 57 percent were made by fossil-fuel and nuclear powerplants; about 36 percent were for public-water supply; about 4.2 percent was by industrial users, 2.0 percent by domestic users, and about 0.5 percent was for irrigation. Total withdrawals, total surface-water and fresh ground-water withdrawals, in New York are plotted, by county. The categories of public-water supply and thermoelectric power account for the withdrawals that exceed 100 Mgal/d per county. The counties that have public-water supply withdrawals that exceed 100 Mgal/d are: Delaware (453 Mgal/d), Ulster, Nassau, Erie, Sullivan, Westchester, Suffolk, Putnam, and Schoharie (115 Mgal/d). These large withdrawals are from surface water except in Nassau and Suffolk Counties on Long Island, where groundwater is the sole source of freshwater. Delaware, Putnam, Schoharie, Sullivan, Ulster, and Westchester Counties, in the southeastern part of the State, provide surface water to the aqueducts that supply drinking water to New York City. In 2000, the average amount of water delivered to New York City from these counties averaged 1,260 Mgal/d. Erie County, in western New York, had withdrawals totaling 176 Mgal/d of fresh surface water for public-water supply. More freshwater and more total water is withdrawn for the generation of thermoelectric power than for any other water-use category. All of the withdrawals are of surface water. Seven counties have total thermoelectric withdrawals that exceed 500 Mgal/d: Queens (1,690 Mgal/d), Westchester, Oswego, Suffolk, Erie, Orange, and Rockland (560 Mgal/d). The counties of Oswego, Erie, and Orange withdrew only fresh surface water for thermoelectric plants. Their sources of water were Lake Ontario (Oswego County), Niagara River (Erie County), and the Hudson River (Orange County). Queens, Westchester, Suffolk, and Rockland withdraw only saline surface water for the production of thermoelectric power. The sources of saline surface water for the thermoelectric plants in the counties of Queens, Westchester, Suffolk, and Rockland are the estuaries of the Hudson River and East River and bays of the Atlantic Ocean (Long Island Sound and the eastern shore of Jamaica Bay). New York ranked eighth in the United States in 2000 in total withdrawals (fresh and saline water); the States that exceeded New York in total withdrawals are those that have large populations (such as California and Texas) and (or) use large quantities of water for irrigation (such as Florida and Idaho). Of the categories considered for the 2000 compilation, New York did not have nationally significant withdrawals for either irrigation or industrial water use. New York ranked third after California and Texas in withdrawals of freshwater for public supply, in the withdrawal of fresh surface water for public-water supply, in total population, and in number of people served by public-water supplies. New York ranked sixth in total withdrawals for the generation of thermoelectric power and total surface-water withdrawals. Finally, New York ranked fourth in withdrawals of ground water for public supply.

Open-File Report↗

USGS1983

Evidence for two pulses of glaciation during the late Proterozoic in northern Utah and southeastern Idaho

A record of glaciation during late Proterozoic time is preserved in a number of localities extending from the Sheeprock Mountains, Utah, to Pocatello, Idaho, and from the Park City area 40 km east of Salt Lake City to the Deep Creek Range along the Utah-Nevada line. Over much of this area, the glacial deposits and associated rocks thicken westward and form the basal part of a miogeoclinal wedge that accumulated near the late Proterozoic and early Paleozoic continental margin. In the east, such deposits are thin and rest on Archean basement or rocks of Proterozoic Y age; in the west, they are part of thicker sequences in which deposition apparently continued without significant interruption from late Proterozoic into Cambrian time. In many places, the original continuity between the western and eastern parts of the depositional wedge has been obscured by thrusting of Cretaceous and early Tertiary age that carried the thick basinal sequences eastward over those deposited on the continental platform. Recent mapping of Fremont Island in Great Salt Lake, the Wasatch Range between Ogden and Brigham City, and the Sheeprock Mountains shows that glacial episodes represented either by diamictite or by dropstones enclosed in finegrained laminated beds are separated by as much as 1,000 m of non-glacial deposits, including black slate, alternating graywacke and siltstone, quartzite, and conglomerate. Using reasonable sedimentation rates for such deposits and by comparison with modern analogues, we infer that two episodes of glaciation, each probably consisting of multiple advances and retreats, were separated by a non-glacial interval of a few hundred thousand to a few million years' duration. Correlation of the allochthonous, miogeoclinal glacial deposits with the single glacial unit present in autochthonous and parautochthonous platform sites is uncertain, but our interpretation of sedimentary facies and paleogeography suggests that only the younger of the two episodes recorded in the allochthon is represented by the diamictites of the autochthon.

Idaho, Utah↗

USGS1953

Floods of May-July 1950 in southeastern Nebraska

Four floods occurred in southeast Nebraska during the period of May to July 1950. Two of these were the greatest known in the State if the size of the drainage areas is considered, and the other two were not so spectacular but were of notable size and of possible hydrologic significance in their relation to the two major floods. Although property loss and damage have been exceeded in previous floods in Nebraska, notably in the flood of May-June 1935 on the Republican River, they were extremely high in the period covered by this report. Loss of life, which resulted largely from the rapid cresting of the streams, was likewise high. Each of the floods was caused by heavy precipitation, which at times reached intensities seldom recorded in the Missouri River basin. On May 8, 1950, more than 14 inches of rain fell over certain areas of the Little Nemaha River basin within a period of a few hours. One center of the storm of July 8, 1950,occurred at York, Nebr., where 11 inches of rain was recorded within a 4-hour period, and the storm total exceeded 13 inches. Notable high rates of discharge produced by the intense rainfall were 1,030 cfs per square mile from 218 square miles of drainage area in the Little Nemaha River basin on May 9, 1950; 1,020 cfs per square mile from 2.5 square miles drainage area in the Elkhorn River basin on June 2, 1950; and 3,320 cfs per square mile from 6.93 square miles of drainage area in the Big Blue River basin on July 9, 1950. This report presents records of stage and discharge for the flood. periods at 36 stream-gaging stations in southeast Nebraska, and a summary of peak discharges, with comparative data for previously known floods at 45 measurement points. The report also includes a discussion of the weather associated with the floods and other data pertinent to the floods.

Water Supply Paper↗

USGS2003

Bedrock, soil, and lichen geochemistry from Isle Royale National Park, Michigan

Isle Royale National Park, Michigan, is a large island in northeastern Lake Superior that became a national park in 1940 and was designated as a wilderness area in 1976. The relative isolation of Isle Royale (Figure 1), 25 kilometers out in Lake Superior from the Canadian mainland, its generally harsh climate, and its status as a wilderness national park have minimized human influence on the geochemical evolution of its landscape. USGS sampling on Isle Royale began in 1996 as part of a larger project on the geology of the Midcontinent rift in the Lake Superior region and continued through 2000. Sampling began with collecting bedrock samples to characterize the geochemistry of the volcanic rocks that make up the much of the island, as well as samples representative of the minor native copper mineralization found on the island. Preliminary results from the bedrock study indicated, among other findings, that basaltic bedrock on the island had no detectable mercury, but that there was an association between native copper mineralization and trace amounts of mercury (Cannon and Woodruff, 1999). This finding and the recognition by the National Park Service that 6 of 32 inland lakes on Isle Royale have mercury levels in game fish that exceed State of Michigan acceptable levels for human consumption (Kallemeyn, 2000) resulted in renewed sampling on the island focused more on environmental issues. To evaluate atmospheric inputs of mercury and other elements to soil geochemistry, regionally distributed samples of both soils and lichens were collected as paired samples across the entire island. At each soil sample site, three epiphytic (grows in trees) lichen species, Evernia mesomorpha , Hypogymnia plysodes , and Parmelia sucata , were always collected. At some sites Cladina rangiferina , a lichen that grows on bare bedrock and soil surfaces, was also collected. The occurrence of Cladina rangiferina on the island is somewhat limited, and so this lichen species was not collected at all sites. A high density of soil samples was collected within three individual watersheds (Sargent Lake, Lake Wagejo, and Lake Richie) for a localized study that evaluated the terrestrial distribution of mercury and other elements of environmental concern. These lakes were chosen using data from Kallemeyn (2000) that showed that Sargent Lake and Lake Wagejo have high mercury in fish, whereas Lake Richie, which is similar in size to Sargent Lake, does not. As part of this study on the terrestrial contribution of mercury to lakes, long cores of lake sediments were recovered from Sargent Lake and Lake Richie using a modified Livingston piston sampler. For an ancillary study that evolved from the study on the distribution of mercury in certain watersheds, some soil samples were collected to evaluate the impact of forest fire on soil geochemistry, deliberately sampling within and outside areas on the island that burned in severe forest fires in 1936. To complete bedrock sampling on the island, rock samples from the Copper Harbor Formation, a sedimentary unit that occurs on the southeastern part of the island were collected in 1999. This report presents all the geochemical data from samples collected by the USGS during this period (Figures 1 and 2). A number of reports presenting data interpretation are in preparation

Michigan↗

USGS2015

Late Holocene sea- and land-level change on the U.S. southeastern Atlantic Coast

Late Holocene relative sea-level (RSL) reconstructions can be used to estimate rates of land-level (subsidence or uplift) change and therefore to modify global sea-level projections for regional conditions. These reconstructions also provide the long-term benchmark against which modern trends are compared and an opportunity to understand the response of sea level to past climate variability. To address a spatial absence of late Holocene data in Florida and Georgia, we reconstructed ~ 1.3 m of RSL rise in northeastern Florida (USA) during the past ~ 2600 years using plant remains and foraminifera in a dated core of high salt-marsh sediment. The reconstruction was fused with tide-gauge data from nearby Fernandina Beach, which measured 1.91 ± 0.26 mm/year of RSL rise since 1900 CE. The average rate of RSL rise prior to 1800 CE was 0.41 ± 0.08 mm/year. Assuming negligible change in global mean sea level from meltwater input/removal and thermal expansion/contraction, this sea-level history approximates net land-level (subsidence and geoid) change, principally from glacio-isostatic adjustment. Historic rates of rise commenced at 1850–1890 CE and it is virtually certain ( P = 0.99) that the average rate of 20th century RSL rise in northeastern Florida was faster than during any of the preceding 26 centuries. The linearity of RSL rise in Florida is in contrast to the variability reconstructed at sites further north on the U.S. Atlantic coast and may suggest a role for ocean dynamic effects in explaining these more variable RSL reconstructions. Comparison of the difference between reconstructed rates of late Holocene RSL rise and historic trends measured by tide gauges indicates that 20th century sea-level trends along the U.S. Atlantic coast were not dominated by the characteristic spatial fingerprint of melting of the Greenland Ice Sheet.

Florida↗

USGS2008

Nutrient Concentrations and Their Relations to the Biotic Integrity of Nonwadeable Rivers in Wisconsin

Excessive nutrient [phosphorus (P) and nitrogen (N)] input from point and nonpoint sources is frequently associated with degraded water quality in streams and rivers. Point-source discharges of nutrients are fairly constant and are controlled by the U.S. Environmental Protection Agency's (USEPA) National Pollutant Discharge Elimination System. To reduce inputs from nonpoint sources, agricultural performance standards and regulations for croplands and livestock operations are being proposed by various States. In addition, the USEPA is establishing regionally based nutrient criteria that can be refined by each State to determine whether actions are needed to improve water quality. More confidence in the environmental benefits of the proposed performance standards and nutrient criteria would be possible with improved understanding of the biotic responses to a range of nutrient concentrations in different environmental settings. To achieve this general goal, the U.S. Geological Survey and the Wisconsin Department of Natural Resources collected data from 282 streams and rivers throughout Wisconsin during 2001 through 2003 to: (1) describe how nutrient concentrations and biotic-community structure differ throughout the State, (2) determine which environmental characteristics are most strongly related to the distribution of nutrient concentrations and biotic-community structure, (3) determine reference conditions for water quality and biotic indices for streams and rivers in the State, (4) determine how the biotic communities in streams and rivers in different areas of the State respond to differences in nutrient concentrations, (5) determine the best regionalization scheme to describe the patterns in reference conditions and the corresponding responses in water quality and the biotic communities (primarily for smaller streams), and (6) develop algorithms to estimate nutrient concentrations in streams and rivers from a combination of biotic indices. The ultimate goal of this study is to provide the information needed to guide the development of regionally based nutrient criteria for Wisconsin streams and rivers. In this report, data collected, primarily in 2003, from 42 nonwadeable rivers are used to describe nutrient concentrations and their relations to the biotic integrity of rivers in Wisconsin. In a separate report by Robertson and others (2006a), the data collected from 240 wadeable streams are used to describe these relations in streams in Wisconsin. Reference water-quality conditions for nonwadeable rivers were found to be similar throughout Wisconsin (approximately 0.035 milligrams per liter (mg/L) for total P (TP), 0.500 mg/L for total N (TN), 4 micrograms per liter for suspended chlorophyll a (SCHL), and greater than 110 centimeters for Secchi-tube depth (SD)). For each category of the biotic community (SCHL, macroinvertebrates, and fish), a few indices were more strongly related to differences in nutrient concentrations than were others. For the indices most strongly related to nutrient concentrations, reference conditions were obtained with a regression approach, from values corresponding to the worst 75th-percentile value from a subset of minimally impacted streams (streams having reference nutrient concentrations), and from the best 25th-percentile value of all the data. Concentrations of TP and TN in nonwadeable rivers increased as the percentage of agricultural land in the basin increased; these increases resulted in increased SCHL concentrations and decreased SDs. The responses in SDs and SCHL concentrations to changes in nutrient concentrations were similar throughout most of the State except in rivers in the southeastern part, where SCHL concentrations were lower than would be expected given their nutrient concentrations. Rivers in the southeastern part of the State had high concentrations of total suspended sediment compared to the SCHL concentrations. Many biotic indices responded to increases in nu

Professional Paper↗

USGS1994

Sources of dissolved salts in the central Murray Basin, Australia

Large areas of the Australian continent contain scattered saline lakes underlain by shallow saline groundwaters of regional extent and debated origin. The normative salt composition of subsurface pore fluids extracted by squeezing cores collected during deep drilling at Piangil West 2 in the central Murray Basin in southeastern Australia, and of surface and shallow subsurface brines produced by subaerial evaporation in the nearby Lake Tyrrell systems, helps constrain interpretation of the origin of dissolved solutes in the groundwaters of this part of the continent. Although regional sedimentation in the Murray Basin has been dominantly continental except for a marine transgression in Oligocene-Pliocene time, most of the solutes in saline surface and subsurface waters in the central Murray Basin have a distinctly marine character. Some of the Tyrrell waters, to the southwest of Piangil West 2, show the increase in NaCl and decrease in sulfate salts expected with evaporative concentration and gypsum precipitation in an ephemeral saline lake or playa environment. The salt norms for most of the subsurface saline waters at Piangil West 2 are compatible with the dilution of variably fractionated marine bitterns slightly depleted in sodium salts, similar to the more evolved brines at Lake Tyrrell, which have recharged downward after evaporation at the surface and then dissolved a variable amount of gypsum at depth. Apparently over the last 0.5 Ma significant quantities of marine salt have been blown into the Murray Basin as aerosols which have subsequently been leached into shallow regional groundwater systems basin-wide, and have been transported laterally into areas of large evaporative loss in the central part of the basin. This origin for the solutes helps explain why the isotopic compositions of most of the subsurface saline waters at Piangil West 2 have a strong meteoric signature, whereas the dissolved salts in these waters appear similar to a marine assemblage. ?? 1994.

Chemical Geology↗

USGS1997

Reinterpretation of the peninsular Florida Oligocene: An integrated stratigraphic approach

A very thick (> 300 m) nearly continuous Oligocene section exists in southern peninsular Florida, as revealed by lithostratigraphic, biostratigraphic (mollusks and dinocysts), chronostratigraphic (Sr isotopes) and petrographic analyses of twelve cores and two quarries. The Oligocene deposits in the subsurface of southern Florida are the thickest documented in the southeastern U.S., and they also may represent the most complete record of Oligocene deposition in this region. No major unconformities within the Oligocene section are detected in the southern portion of the peninsula; hiatuses at the Eocene-Oligocene boundary, the early Oligocene-late Oligocene boundary, and the late Oligocene-Miocene boundary, are of limited duration if they exist at all. No significant disconformity is recognized between the Suwannee Limestone and the Arcadia Formation in southern Florida. However, on the east coast of Florida a hiatus of more than 12 m.y., spanning from at least the middle of the early Oligocene to early Miocene is present. The Suwannee Limestone was deposited during the early Oligocene. The top of the Suwannee Limestone appears to be diachronous across the platform. The 'Suwannee' Limestone, previously identified incorrectly as a late Oligocene unit, is herein documented to be early Oligocene and is encompassed in the lower Oligocene Suwannee Limestone. An unnamed limestone, found on the east coast of the peninsula is, at least in part, correlative with the Suwannee Limestone. The Arcadia Formation, basal Hawthorn Group, accounts for a large portion of the Oligocene deposition in southern Florida, spanning the interval from the middle of the early Oligocene to at least the early Miocene. Comparisons of the depositional patterns, and the distribution of dolomite and phosphate within the Suwannee Limestone and the Arcadia Formation, suggest fluctuating sea levels and that the paleo-Gulf Stream played a role in determining the nature and extent of Oligocene deposition in peninsular Florida.

Florida↗

USGS2003

Geologic map of the Nelson quadrangle, Lewis and Clark County, Montana

The geologic map of the Nelson quadrangle, scale 1:24,000, was prepared as part of the Montana Investigations Project to provide new information on the stratigraphy, structure, and geologic history of an area in the geologically complex southern part of the Montana disturbed belt. In the Nelson area, rocks ranging in age from Middle Proterozoic through Cretaceous are exposed on three major thrust plates in which rocks have been telescoped eastward. Rocks within the thrust plates are folded and broken by thrust faults of smaller displacement than the major bounding thrust faults. Middle and Late Tertiary sedimentary and volcaniclastic rocks unconformably overlie the pre-Tertiary rocks. A major normal fault displaces rocks of the western half of the quadrangle down on the west with respect to strata of the eastern part. Alluvial and terrace gravels and local landslide deposits are present in valley bottoms and on canyon walls in the deeply dissected terrain. Different stratigraphic successions are exposed at different structural levels across the quadrangle. In the northeastern part, strata of the Middle Cambrian Flathead Sandstone, Wolsey Shale, and Meagher Limestone, the Middle and Upper Cambrian Pilgrim Formation and Park Shale undivided, the Devonian Maywood, Jefferson, and lower part of the Three Forks Formation, and Lower and Upper Mississippian rocks assigned to the upper part of the Three Forks Formation and the overlying Lodgepole and Mission Canyon Limestones are complexly folded and faulted. These deformed strata are overlain structurally in the east-central part of the quadrangle by a succession of strata including the Middle Proterozoic Greyson Formation and the Paleozoic succession from the Flathead Sandstone upward through the Lodgepole Limestone. In the east-central area, the Flathead Sandstone rests unconformably on the middle part of the Greyson Formation. The north edge, northwest quarter, and south half of the quadrangle are underlain by a succession of rocks that includes not only strata equivalent to those of the remainder of the quadrangle, but also the Middle Proterozoic Newland, Greyson, and Spokane Formations, Pennsylvanian and Upper Mississippian Amsden Formation and Big Snowy Group undivided, the Permian and Pennsylvanian Phosphoria and Quadrant Formations undivided, the Jurassic Ellis Group and Lower Cretaceous Kootenai Formation. Hornblende diorite sills and irregular bodies of probable Late Cretaceous age intrude Middle Proterozoic, Cambrian and Devonian strata. No equivalent intrusive rocks are present in structurally underlying successions of strata. In this main part of the quadrangle, the Flathead Sandstone cuts unconformably downward from south to north across the Spokane Formation into the upper middle part of the Greyson Formation. Tertiary (Miocene?) strata including sandstone, pebble and cobble conglomerate, and vitric crystal tuff underlie, but are poorly exposed, in the southeastern part of the quadrangle where they are overlain by late Tertiary and Quaternary gravel. The structural complexity of the quadrangle decreases from northeast to southwest across the quadrangle. At the lowest structural level (Avalanche Butte thrust plate) exposed in the canyon of Beaver Creek, lower and middle Paleozoic rocks are folded in northwest-trending east-inclined disharmonic anticlines and synclines that are overlain by recumbently folded and thrust faulted Devonian and Mississippian rocks. The Mississippian strata are imbricated adjacent to the recumbent folds. In the east-central part of the quadrangle, a structurally overlying thrust plate, likely equivalent to the Hogback Mountain thrust plate of the Hogback Mountain quadrangle adjacent to the east (Reynolds, 20xx), juxtaposes recumbently folded Middle Proterozoic and unconformably overlying lower Paleozoic rocks on the complexly folded and faulted rocks of the Avalanche Butte thrust plate. The highest structural plate, bounded below

IMAP↗

USGS2000

Contrasting methods of fracture trend characterization in crystalline metamorphic and igneous rocks of the Windham quadrangle, New Hampshire

The bedrock of the Windham quadrangle in southeastern New Hampshire consists of deformed early Palaeozoic crystalline metamorphic and intrusive igneous rocks intruded by Mesozoic igneous dikes. Generally, less common northeast striking, steeply dipping fractures developed sub-parallel to the pre-existing tectonic foliation in the Palaeozoic rocks. Mesozoic lamprophyre and diabase dikes intruded along the northeast trending fractures, utilizing the pre-existing anisotropy in the crystalline rocks. Northwest striking, steeply dipping systematic joints and joint sets are the most prominent fractures in the area and, at least in part, post-date the Mesozoic dikes. Sub-horizontal sheeting joints occur in all rock types. Locally, the coincidence of the sub-horizontal fractures with a sub-horizontal Paleozoic cleavage suggests that some of the sheeting fractures utilized the pre-existing ductile anisotropy during unloading. Generally, the metasedimentary rocks show a less complex pattern of fracturing than the intrusive rocks suggesting that rock type is a controlling factor. Metasedimentary rocks in the biotite zone and well-foliated igneous rocks show a greater tendency to fracture along pre-existing bedding and foliation surfaces than metasedimentary rocks in the garnet zone and poorly foliated igneous rocks. A comparison of mapped fracture data and station fracture data indicates that either mapped data or station data can be used to identify regional fracture trends. Local fracture trends can not be identified by limited measurements at a few fracture stations, however, because they do not address spatial variability. Some fracture trends may be scale-dependant because they may be either unique to a local area or present only at regional scales.

Northeastern Geology and Environmental Sciences↗

USGS2021

Water-level conditions in the confined aquifers of the New Jersey Coastal Plain, 2013

The Coastal Plain aquifers of New Jersey provide an important source of water for more than 3.5 million people. In 2013, groundwater withdrawals from 10 confined aquifers of the New Jersey Coastal Plain totaled about 190 million gallons per day. Steadily increasing withdrawals from the late 1800s to the early 1990s resulted in declining water levels and the formation of regional cones of depression in many confined Coastal Plain aquifers. Starting in 1978, the U.S. Geological Survey (USGS) began mapping the potentiometric surfaces of the major confined Coastal Plain aquifers every 5 years to provide a regional assessment of groundwater conditions. In a study conducted by the USGS, in cooperation with the New Jersey Department of Environmental Protection, water levels in 10 confined aquifers of the New Jersey Coastal Plain were measured and evaluated to provide a regional overview of groundwater conditions during fall 2013. Water levels were measured in 987 wells in New Jersey, and parts of Pennsylvania and Delaware. Potentiometric-surface maps were prepared for, in ascending order of age, the confined Cohansey aquifer of Cape May County, Rio Grande water-bearing zone, Atlantic City 800-foot sand, Piney Point aquifer, Vincentown aquifer, Wenonah-Mount Laurel aquifer, Englishtown aquifer system, and the Upper, Middle, and Lower aquifers of the Potomac-Raritan-Magothy (PRM) aquifer system. Persistent, regionally extensive cones of depression were present in the potentiometric surfaces of the Englishtown aquifer system and Wenonah-Mount Laurel aquifer in Ocean and Monmouth Counties; Wenonah-Mount Laurel and Upper, Middle, and Lower PRM aquifers in Camden County; and Atlantic City 800-foot sand in Atlantic County. Changes in water levels from 2008 to 2013 were measured in many Coastal Plain aquifers in New Jersey. In some areas, water levels continued to decline as a result of pumping, but in other areas water levels continued to recover as a result of regulated decreases in groundwater withdrawals. Since 2008, in the confined Cohansey aquifer in Cape May County, water levels generally did not change; however, cones of depression in the potentiometric surface of the Piney Point aquifer in some areas of Cumberland County deepened by more than 20 feet (ft). In Critical Area 1, an area of restricted withdrawals, measured water levels in the Wenonah-Mount Laurel aquifer declined in parts of southern Monmouth County by more than 10 ft; however, rises in water levels of more than 10 ft were measured in parts of northern Ocean and Monmouth Counties. Since 2008, in Critical Area 2, also an area of restricted withdrawals, measured water levels in the Wenonah-Mount Laurel aquifer rose more than 20 ft in parts of western Burlington County and more than 20 ft in parts of western Camden County. Since 2008, in Critical Area 1, measured water levels in the Englishtown aquifer system declined in parts of eastern Ocean County by more than 10 ft and in southeastern Monmouth County by more than 20 ft; however, rises in water levels of more than 10 ft were measured in other parts of Ocean and Monmouth Counties. In general, since 2008 in Critical Area 2, in the Upper PRM aquifer, measured water levels continued to rise by 10 ft or more in central and western Burlington and central Camden Counties. In the Middle PRM aquifer in Critical Area 2, measured water levels rose in parts of central Camden County by 10 ft or more. However, measured water levels in the Lower PRM aquifer in Critical Area 2 were more than 10 ft lower in the center of the cone of depression in central Camden County, but measured water levels continued to rise updip from this area in Critical Area 2. Seasonal water-level fluctuations are presented in time-series hydrographs for 77 wells during 1978–2013. Analyses of long-term water-level changes for the period 2008–13 indicate downward water-level trends at 14 wells (18 percent), upward trends at 34 wells (44 percent), and no substantial change at 29 wells (38 percent). Downward trends were most often observed for wells screened in the Piney Point aquifer and the Atlantic City 800-foot sand. Upward water-level trends were most often measured for wells screened in the PRM aquifer system. Upward water-level trends also were measured for wells in the Englishtown aquifer system and the Wenonah-Mount Laurel aquifer in Critical Area 1 in some areas; however, downward trends and no substantial changes were measured in other areas.

New Jersey↗

USGS2021

Extreme Quaternary plate boundary exhumation and strike slip localized along the southern Fairweather fault, Alaska, USA

The Fairweather fault (southeastern Alaska, USA) is Earth’s fastest-slipping intracontinental strike-slip fault, but its long-term role in localizing Yakutat–(Pacific–)North America plate motion is poorly constrained. This plate boundary fault transitions northward from pure strike slip to transpression where it comes onshore and undergoes a <25°, 30-km-long restraining double bend. To the east, apatite (U-Th)/He (AHe) ages indicate that North America exhumation rates increase stepwise from ~0.7 to 1.7 km/m.y. across the bend. In contrast, to the west, AHe age-depth data indicate that extremely rapid 5–10 km/m.y. Yakutat exhumation rates are localized within the bend. Further northwest, Yakutat AHe and zircon (U-Th)/He (ZHe) ages gradually increase from 0.3 to 2.6 Ma over 150 km and depict an interval of extremely rapid >6–8 km/m.y. exhumation rates that increases in age away from the bend. We interpret this migration of rapid, transient exhumation to reflect prolonged advection of the Cenozoic–Cretaceous sedimentary cover of the eastern Yakutat microplate through a stationary restraining bend along the edge of the North America plate. Yakutat cooling ages imply a long-term strike-slip rate (54 ± 6 km/m.y.) that mimics the millennial (53 ± 5 m/k.y.) and decadal (46 mm/yr) rates. Fairweather fault slip can account for all Pacific–North America relative plate motion throughout Quaternary time and indicates stability of highly localized plate boundary strike slip on a single fault where extreme rock uplift rates are persistently localized within a restraining bend.

Alaska↗

USGS2015

Water-level altitudes 2015 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2014 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers. 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 water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured cumulative compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains regional-scale maps depicting approximate 2015 water-level altitudes (represented by measurements made during December 2014–March 2015) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2014–15) water-level changes for each aquifer; maps depicting approximate contoured 5-year (2010–15) water-level changes for each aquifer; maps depicting approximate contoured long-term (1990–2015 and 1977–2015) water-level changes for the Chicot and Evangeline aquifers; a map depicting approximate contoured long-term (2000–15) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured cumulative compaction of subsurface sediments at the borehole extensometers during 1973–2014. Three tables listing the water-level data used to construct each water-level map for each aquifer and a table listing the measured cumulative compaction data for each extensometer site and graphs are included. In 2015, water-level-altitude contours for the Chicot aquifer ranged from 175 feet (ft) below the vertical datum (the National Geodetic Vertical Datum of 1929 or the North American Vertical Datum of 1988; hereinafter, datum) in a localized area in northwestern Harris County to 200 ft above datum in northern and western Montgomery County. Water-level changes for 2014–15 in the Chicot aquifer ranged from a 24-ft decline to a 31-ft rise. Contoured 5-year and long-term water-level changes in the Chicot aquifer ranged from a 40-ft decline to a 40-ft rise (2010–15), from a 100-ft decline to a 100-ft rise (1990–2015), and from a 100-ft decline to a 200-ft rise (1977–2015). In 2015, water-level-altitude contours for the Evangeline aquifer ranged from 250 ft below datum in a localized area extending from south-central Montgomery County into north-central Harris County and in an additional area located in central Harris County to 200 ft above datum in southeastern Grimes and northwestern Montgomery Counties. Water-level changes for 2014–15 in the Evangeline aquifer ranged from a 66-ft decline to a 78-ft rise. Contoured 5-year and long-term water-level changes in the Evangeline aquifer ranged from a 60-ft decline to an 80-ft rise (2010–15), from a 200-ft decline to a 240-ft rise (1990–2015), and from a 320-ft decline to a 240-ft rise (1977–2015). In 2015, water-level-altitude contours for the Jasper aquifer ranged from 200 ft below datum in south-central Montgomery County that extends into north-central Harris County to 250 ft above datum in northwestern Montgomery County. Water-level changes for 2014–15 in the Jasper aquifer ranged from a 17-ft decline to a 35-ft rise. Contoured 5-year and long-term water-level changes in the Jasper aquifer ranged from a 60-ft decline to four small, localized areas of 10-ft rises (2010–15) and from a 220-ft decline to no change (2000–15). Compaction of subsurface sediments (mostly in the fine-grained silt and clay layers) composing the Chicot and Evangeline aquifers was recorded continuously by using analog technology at the 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2014, measured cumulative compaction at the 13 extensometers ranged from 0.101 ft at the Texas City-Moses Lake extensometer to 3.668 ft at the Addicks extensometer. During 2014, a total of 10 of the 13 extensometers recorded a slight net decrease of land-surface elevation; the extensometers at the Lake Houston and Clear Lake (shallow) sites recorded slight net increases of land-surface elevation, and the extensometer at the Texas City-Moses Lake site recorded no change in elevation. The rate of compaction varies from site to site because of differences in rates of groundwater withdrawal in the areas adjacent to each extensometer site and differences among sites in the ratios of sand, silt, and clay and compressibilities of the subsurface sediments. It is not appropriate, therefore, to extrapolate or infer a rate of compaction for an adjacent area on the basis of the rate of compaction measured at nearby extensometers.

Texas↗

USGS2022

Mapping areas of groundwater susceptible to transient contamination events from rapid infiltration into shallow fractured-rock aquifers in agricultural regions of the conterminous United States

Current time-invariant groundwater vulnerability assessments may not capture intermittent contamination events in landscape areas that experience rapid infiltration following precipitation or snowmelt. Occurrences of rapid infiltration and intermittent degradation of groundwater quality are frequently reported in fractured-rock aquifers. This investigation identifies landscape areas underlain by fractured rock within the conterminous United States (CONUS) that may be susceptible to rapid infiltration and where groundwater is a principal source of water supply to the population. Our analysis shows that approximately 27 percent of the CONUS, corresponding to a population of approximately 150 million people, is both underlain by fractured rock and denoted as an area of significant groundwater use. The results of this survey identified shallow fractured-rock aquifers underlying glacial sediments in the upper Midwest and northeastern United States as areas that may be subject to rapid infiltration events. Additionally, aquifers associated with the early Mesozoic basins located in the northeastern and mid-Atlantic United States and bands of carbonate aquifers in the southeastern United States show high susceptibility to rapid infiltration. Index values used in this investigation indicate isolated areas in the western half of the United States also show high susceptibility to rapid infiltration. The isolated areas in Oklahoma, Texas, Arkansas, and southwestern Missouri correspond to karst regions of carbonate aquifers. The isolated areas showing high susceptibility to rapid infiltration and contamination from agricultural sources are locations where more detailed investigations of transient contamination events are warranted. This survey also addresses the potential for contaminant longevity in fractured-rock aquifers stemming from intermittent contamination events. Contaminants that can dissolve into the groundwater following infiltration may be introduced into fractures, and the dissolved constituents can diffuse from fractures into the porosity of the adjacent rock matrix. These constituents can then diffuse back into permeable fractures and adversely affect groundwater quality at downgradient locations over an extended time frame. Rock types with larger matrix porosities have the capacity to retain and then release larger quantities of dissolved constituents, resulting in longer residence times for dissolved groundwater contaminants. The magnitude of the dissolved contaminant concentration infiltrating to the water table will also dictate whether the contaminant concentration in the groundwater exceeds limits for human consumption over the duration of a contamination event. In general, sedimentary- and carbonate-rock aquifers have larger matrix porosities in comparison to igneous- and metamorphic-rock aquifers, and thus, they are more susceptible to longer contaminant residence times. Aquifers composed of sedimentary or carbonate rock constitute approximately 51 percent of the CONUS, and 19 percent of the CONUS is associated with sedimentary- or carbonate-rock aquifers that are of significance for groundwater use. Depending on the contaminants of concern and the concentration of the contaminants introduced into the groundwater from infiltrating water, it would be beneficial for investigations of susceptibility to rapid infiltration to also consider the potential for contaminant longevity. This investigation identifies areas of rapid infiltration into fractured rock using index values applied to the attributes (1) depth to the water table, (2) depth to bedrock, and (3) percentage of sand in soil, where larger index values indicate a greater susceptibility to rapid infiltration. These attributes are selected as the most likely factors that affect rapid infiltration to the water table. The combination of depth to water table and depth to bedrock highlight those aquifer settings that are characterized as shallow fractured-rock aquifers, where the water table may reside either in the bedrock or in overlying unconsolidated geologic materials. In addition, we consider the percentage of agricultural use as a land-use attribute when formulating an index of susceptibility to rapid infiltration and contamination. Agricultural areas are well recognized as nonpoint sources of contaminants that can affect groundwater quality because of seasonal amendments applied to the land surface. Rural agricultural areas are also characterized by septic tanks and leach fields for onsite treatment of wastewater, which may also be a source of contamination that may be introduced into the groundwater following precipitation or snowmelt events.

Conterminous United States↗

USGS1987

Heat transport by fluids during late Cretaceous regional metamorphism in the Big Maria Mountains, southeastern California

The Big Maria Mountains of southeastern California comprise a Late Cretaceous regional metamorphic terrain involving Paleozoic cratonal sediments. Siliceous limestone of the upper Paleozoic Supai Formation has reacted to form massive wollastonite, requiring an enormous fluid flux. The minimum volume ratio of fluid:rock that is necessary to explain the formation of wollastonite may be calculated from the reaction quartz + calcite = wollastonite + CO 2 , using the method of Rice and Ferry. Given average conditions of 3 kbar, 500 °C, an infiltrating fluid of composition X H2O = 1.00, an equilibrium fluid composition of X H2O = 0.97, and 90% wollastonite in the final rock, a fluid:rock ratio of 17:1 may be calculated. Infiltrating fluids of composition 1.00 > X H2O > 0.97 require still higher ratios. Metamorphic reactions which took place in other units of the sequence (metapelites, massive carbonates, metavolcaniclastics) did not record the massive fluid flux, but fluids must have passed through them to have affected structurally isolated masses of Supai Formation. Passage of fluids must have occurred along fractures. Neither magmatism nor radioactive heat sources are adequate to explain the temperatures of metamorphism. If the minimum quantity of fluid that is estimated to have passed through the area was initially at 680 °C, it would result in a 300-degree rise in temperature over that of the stable-craton geotherm. Late metamorphic pegmatite dikes which are most abundant in areas of high metamorphic grade may stem from melts anatectically derived at deeper levels, perhaps as a result of the same fluid flux. Heat that is introduced by large fluid fluxes may be an important cause of anomalously high temperatures which are observed in many cases in regional metamorphic terrains.

California↗

USGS1971

Nomenclature and correlation of some upper Precambrian and basal Cambrian sequences in western Utah and southeastern Idaho

Recent stratigraphic studies in three widely separated localities in southeastern Idaho and western Utah have revealed a startling continuity of both individual rock units and of rock sequences over a distance of some 300 mi parallel to the strike of a late Precambrian and Cambrian depositional trough. Between 15,000 and 25,000 ft of beds were deposited in the axis of the trough, whereas only 1000 to 3300 ft of correlative rocks were laid down on the shelf to the east. In several areas a diamictite is present near the base of the sequence; this is underlain locally and overlain generally by argillites containing lenticular limestones and dolomites; these in turn are succeeded by quartzitic rocks containing a thick grayish-red to maroon unit—the Mutual Formation. In each area the sequence includes, at the top, quartzites typical of the basal Cambrian. Deposition in the basin was essentially continuous from late Precambrian into Cambrian time but was interrupted by uplift and erosion on the shelf. The hinge line of the ancient seaway is inferred to have coincided roughly with the present “Wasatch line,” but erosion prior to deposition of the Tintic Quartzite has removed most of the data needed to establish this with certainty. Rocks in each of the three areas described here in detail are regarded as allochthonous and appear to have been thrust eastward during the Sevier orogeny. A precise reconstruction of the sedimentary basin must therefore await not only additional stratigraphic studies in such areas as the Promontory Range of Utah and the Bannock and Malad Ranges of southern Idaho, but also final resolution of the structural events.

Idaho, Utah↗