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At least 973 records · Page 54Linked to original sources

USGS1992

Aquifer-test results, direction of ground-water flow, and 1984-90 annual ground-water pumpage for irrigation, lower Big Lost River Valley, Idaho

The study area (see index map of Idaho), part of the Big Lost River drainage basin, is at the northern side of the eastern Snake River Plain. The lower Big Lost River Valley extends from the confluence of Antelope Creek and the Big Lost River to about 4 mi south of Arco and encompasses about 145 mi 2 (see map showing water-level contours). The study area is about 18 mi long and, at its narrowest, 4 mi wide. Arco, Butte City, and Moore, with populations of 1,016, 59, and 190, respectively, in 1990, are the only incorporated towns. The entire study area, except the extreme northwestern part, is in Butte City. The study area boundary is where alluvium and colluvium pinch out and abut against the White Knob Mountains (chiefly undifferentiated sedimentary rock with lesser amounts of volcanic rock) on the west and the Lost River Range (chiefly sedimentary rock) on the east. Gravel and sand in the valley fill compose the main aquifer. The southern boundary is approximately where Big Lost River valley fill intercalates with or abuts against basalt of the Snake River Group. Spring ground-water levels and flow in the Big Lost River depend primarily on temperature and the amount and timing of precipitation within the entire drainage basin. Periods of abundant water supply and water shortages are, therefore, related to the amount of annual precipitation. Surface reservoir capacity in the valley (Mackay Reservoir, about 20 mi northwest of Moore) is only 20 percent of the average annual flow of the Big Lost River (Crosthwaite and others, 1970, p. 3). Stored surface water is generally unavailable for carryover from years of abundant water supply to help relieve drought conditions in subsequent years. Many farmers have drilled irrigation wells to supplement surface-water supplies and to increase irrigated acreage. Average annual flow of the Big Lost River below Mackay Reservoir near Mackay (gaging station 13127000, not shown) in water years 1905, 1913-14, and 1920-90 was about 224,600 acre-ft; average annual flow of the Big Lost River near Arco (gaging station 13132500; see map showing water-level contours) in water years 1947-61, 1967-80, and 1983-90 was about 79,000 acre-ft (Harenberg and others, 1991, p. 254-255). Moore Canal and East Side Ditch divert water from the Big Lost River at the Moore Diversion, 3 mi north of Moore (see map showing water-level contours) and supply water for irrigation near the margins of the valley. When water supply is average or greater, water in the Big Lost River flows through the study area and onto the Snake River Plain, where it evaporates or infiltrates into the Snake River Plain aquifer. When water supply is below average, water in the Big Lost River commonly does not reach Arco; rather, it is diverted for irrigation in the interior of the valley, evaporates, or infiltrates to the valley-fill aquifer. This report describes the results of a study by the U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources, to collect hydrologic data needed to help address water-supply problems in the Big Lost River Valley. Work involved (1) field inventory of 81 wells, including 46 irrigation wells; (2) measurement of water levels in 154 wells in March 1991; (3) estimation of annual ground-water pumpage for irrigation from 1984 through 1990; and (4) analysis of results of an aquifer test conducted southwest of Moore. All data obtained during this study may be inspected at the U.S. Geological Survey, Idaho District office, Boise.

Idaho↗

USGS1946

Lower Middle Ordovician stratigraphy of the Shenandoah Valley, Virginia

In classifying the lower Middle Ordovician of the Shenandoah Valley, the formation names Stones River, Mosheim, Lenoir, Holston, Whitesburg, and Athens have been used without adequate evidence. Detailed study shows that the so-called Athens and Whitesburg, as developed near Harrisonburg, are laterally continuous with the greater part of the Chambersburg limestone, which is supposed to be younger than the Athens. The newly discovered relations of these formations affect the classification of the Middle Ordovician in much of the northern Appalachian region. The present study has been high-lighted by the discovery that Cryptophragmus antiquatus , widely regarded as a valid guide to the lower Black River, ranges through several hundred feet of beds, possibly as high as lower Trenton. In the Shenandoah Valley, this fossil is most abundant near the top of the Chambersburg, which is supposed to be late Black River or early Trenton. In the proposed reclassification, the lower Middle Ordovician is divided into six time-stratigraphic units, in ascending order: the New Market limestone, Whistle Creek limestone, Lincolnshire limestone, Edinburg formation, Oranda formation, and Collierstown limestone. The Edinburg embraces two equivalent facies: one of cobbly limestone (Lantz Mills facies) which is mainly developed in the northern and western parts of the Shenandoah Valley; and a relatively thicker body of black limestone and shale (Liberty Hall facies) which is typically developed in the Harrison-burg-Staunton area. In the western part of Shenandoah County, the topmost division of the Edinburg formation is composed of light-gray calcilutite and calcarenite, named the St. Luke limestone member. The rusty-brown granular limestones just below Butts' Athens in the Harrisonburg-Staunton-Lexington area are here named the Botetourt limestone member of the Edinburg formation. At least part of the New Market limestone is linked with a part of the New York Chazy and type Lenoir, but the Lincolnshire seems to be post-Chazy. All the succeeding beds, comprising the greater part of the lower Middle Ordovician succession, are Black River or Trenton.

Virginia↗

USGS2025

Streamflow extents and hydraulic characteristics of Meadow Valley Wash at Stuart Ranch, near Rox, Nevada

The former Stuart Ranch, now managed by the Bureau of Land Management, is transected by Meadow Valley Wash, where 4,600 feet of perennial stream and adjacent riparian vegetation provide critical habitat for several wildlife and aquatic species protected under the Endangered Species Act. The stream has been altered by prior construction of irrigation diversions, gravel mining, and removal of riparian vegetation, resulting in the loss of instream and riparian vegetation and disconnected floodplains. The stream alteration has also resulted in the loss of native species and increased non-native invasive species and changes in ecological cycles. With the goal of improving habitat extent and quality for native threatened and endangered species, the Bureau of Land Management (BLM) is considering establishing perennial streams through braided side channels by constructing beaver dam analogs, excavating side channel connectors, and grading an irrigation reservoir berm on the floodplain. The U.S. Geological Survey (USGS) provided hydraulic modeling to assist the BLM in evaluating how possible restoration modifications could affect the extent of aquatic, riparian, and other habitat types. Three two-dimensional (2-D) hydraulic models were developed to simulate 2021 conditions (when most of the topographic data were collected), minor restoration modifications (one excavated side channel and a beaver dam analog), and major restoration modifications (three excavated side channels, a beaver dam analog, and an excavated and graded area to remove the irrigation reservoir) to determine streamflow-inundation extents and hydraulic characteristics (depth and velocity) for base flow and various flood (50-, 20-, 10-, 4-, 2-, and 1-percent annual exceedance probability [AEP]) scenarios. An average summer base flow of 0.92 cubic feet per second was estimated based on data from a USGS streamgage in the study area. The 50-, 20-, 10-, 4-, 2-, and 1-percent AEP streamflows were estimated based on a flood-frequency analysis of data from the streamgage. The base flow and AEP floods were combined with surveyed topographic data to create a 2-D unsteady hydraulic model. The hydraulic model was used to simulate the base flow and flood-inundation extents and hydraulic characteristics under 2021 conditions and with two possible restoration modification scenarios. Under 2021 conditions, flow remains in a single channel until the most downstream end of the modeled reach, where flow then expands into slower velocity pools. During floods, streamflow begins to enter the side channels at the 50-percent flood, expands into the east floodplain at 20-percent flood, and flows in the irrigation reservoir at 4-percent flood. Compared to 2021 conditions with no terrain modification, base flow under the possible restoration modifications enters and remains in the side channels, thus increasing the likelihood of expanding riparian habitat. Additionally, during floods under the major restoration modifications, streamflow expands into the modified terrain surrounding the irrigation reservoir at 10-percent AEP, as opposed to 4-percent AEP under 2021 conditions. For all modeled streamflow scenarios, streamflow is deepest in the center of the main and side channels, as well as the downstream pooled areas. Streamflow is fastest in the narrow sections of the channels, especially in the upper 1,220 feet of the modeled reach.

Nevada↗

USGS2021

Characterization of groundwater quality and discharge with emphasis on selenium in an irrigated agricultural drainage near Delta, Colorado, 2017–19

Selenium is a water-quality constituent of concern for aquatic ecosystems in the lower Gunnison River Basin. Selenium is derived from bedrock of the Mancos Shale and is mobilized and transported to groundwater and surface water by application of irrigation water. Although it is recognized that groundwater contributes an appreciable amount of selenium to surface water, few studies have addressed interactions between the two. The U.S. Geological Survey in cooperation with the Colorado Water Conservation Board conducted a study during 2017–19 to characterize the quality and quantity of groundwater discharging to an agricultural drainage near Delta, Colorado, locally known as Sunflower Drain. Water quality in the study area is characterized by high dissolved solids with elevated concentrations of selenium and nitrate resulting from dissolution of soluble salts in the Mancos Shale. Selenium concentrations have decreased by 50 percent since the early 2000s, possibly in response to irrigation system improvements. Stable water isotopes indicate streamflow is dominated by canal water during the irrigation season (April to October) and, during the nonirrigation season (November to March), is dominated by groundwater that has undergone some degree of evaporation. Pesticide and pharmaceutical compounds were infrequently detected, and results indicate they were derived from sources outside the study area such that they do not appear to be useful as tracers of groundwater sources. Stable isotopes of nitrate indicate that nitrate originates from the Mancos Shale, and the isotopic composition is enriched by denitrification in the groundwater system. Using a mass-balance approach, estimated groundwater discharge rates to Sunflower Drain ranged from 0.15 to 0.27 cubic feet per second per mile with one losing reach identified. Selenium, sulfate, and nitrate concentrations in groundwater estimated by mass-balance calculations were similar to concentrations measured in the Poly 17 observation well, located in a largely irrigated area in east tributary. One tributary reach had higher concentrations of selenium, sulfate, and nitrate likely reflecting localized inputs of more concentrated groundwater, similar to the concentrations in the Poly 7 observation well, which is downgradient from a residential area in the west tributary. Three pilot studies were conducted, including fiber optic distributed temperature sensing to detect groundwater discharge zones in the stream channel, a passive seismic technique to estimate depth to bedrock, and use of radon-222 as a geochemical tracer of groundwater discharge. All three techniques show promise as additional approaches for investigating groundwater discharge surface-water systems in irrigated drainage areas on Mancos Shale. The factors that affect groundwater movement mainly include when and where irrigation water is transported and applied, and the distribution of bedrock of the Mancos Shale and overlying alluvial deposits. The average groundwater recharge rate for the study area was estimated at 8.1 inches per year, based on mass balance calculations from synoptic survey data. Along the western tributary of Sunflower Drain, there was evidence that spills from the East Canal may recharge the groundwater aquifer adjacent to the stream channel. Groundwater movement to the stream channel may be controlled by the topography of the alluvial/bedrock interface or focused along human-made features, such as tile drains and ditches constructed around irrigated fields. On larger scales, the top of bedrock was also important, creating a topographic constriction that caused a zone of groundwater discharge. The groundwater system is complex, and further study could better define the system, possibly through application of a groundwater flow model and more extensive studies using some of the exploratory methods evaluated in this study.

Colorado↗

USGS2016

Aquatic Trophic Productivity model: A decision support model for river restoration planning in the Methow River, Washington

Introduction The U.S. Geological Survey (USGS) has developed a dynamic food-web simulation model to provide decision support for Bureau of Reclamation (Reclamation) river restoration projects in the Methow River, Washington. This modeling effort was done to contribute to Reasonable and Prudent Alternative actions 56 and 57of the 2014 Federal Columbia River Power System Biological Opinion (FCRPS BO), which calls for exploration of modeling as a means to help evaluate Endangered Species Act (ESA)-listed fish response to river restoration efforts. In the Methow River, these species of concern include Upper Columbia River (UCR) spring Chinook salmon ( Oncorhynchus tshawytscha ) and UCR summer steelhead ( Oncorhynchus mykiss ). Additionally, the Independent Scientific Advisory Board (ISAB) for the Columbia River has identified the need for modeling (Independent Scientific Advisory Board, 2011a)—including models that incorporate food-web dynamics (Independent Scientific Advisory Board, 2011b)—to better understand how restoration and management strategies might enhance salmon and steelhead populations. Dynamic food-web models, even relatively simple ones, can be valuable tools for exploring responses to river restoration. Although these models have rarely been applied to rivers and streams (but see Mcintire and Colby, 1978; Power and others, 1995), they are commonly used for management decisions in terrestrial and ocean ecosystems (Christensen and Pauly, 1993; Evans and others, 2013). One of the main strengths of these models is that they are rooted in the fundamental laws of thermodynamics (that is, mass balance). Moreover, these models can be easily adapted to different contexts by adding or subtracting different species from the web and by mechanistically linking the dynamics of web members to local environmental conditions, such as water temperature, stream discharge, and channel hydraulics (Power and others, 1995; Doyle, 2006). Alternative management actions can then be evaluated by changing these environmental conditions to simulate potential outcomes following restoration. In this report, we outline the structure of a stream food-web model constructed to explore how alternative river restoration strategies may affect stream fish populations. We have termed this model the “Aquatic Trophic Productivity model” (ATP). We present the model structure, followed by three case study applications of the model to segments of the Methow River watershed in northern Washington. For two case studies (middle Methow River and lower Twisp River floodplain), we ran a series of simulations to explore how food-web dynamics respond to four distinctly different, but applied, strategies in the Methow River watershed: (1) reconnection of floodplain aquatic habitats, (2) riparian vegetation planting, (3) nutrient augmentation (that is, salmon carcass addition), and (4) enhancement of habitat suitability for fish. For the third case study, we conducted simulations to explore the potential fish and food-web response to habitat improvements conducted in 2012 at the Whitefish Island Side Channel, located in the middle Methow River.

Washington↗

USGS2011

Geochemistry of environmentally sensitive trace elements in Permian coals from the Huainan coalfield, Anhui, China

To study the geochemical characteristics of 11 environmentally sensitive trace elements in the coals of the Permian Period from the Huainan coalfield, Anhui province, China, borehole samples of 336 coals, two partings, and four roof and floor mudstones were collected from mineable coal seams. Major elements and selected trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HAAS). The depositional environment, abundances, distribution, and modes of occurrence of trace elements were investigated. Results show that clay and carbonate minerals are the principal inorganic constituents in the coals. A lower deltaic plain, where fluvial channel systems developed successively, was the likely depositional environment of the Permian coals in the Huainan coalfield. All major elements have wider variation ranges than those of Chinese coals except for Mg and Fe. The contents of Cr, Co, Ni, and Se are higher than their averages for Chinese coals and world coals. Vertical variations of trace elements in different formations are not significant except for B and Ba. Certain roof and partings are distinctly higher in trace elements than underlying coal bench samples. The modes of occurrence of trace elements vary in different coal seams as a result of different coal-forming environments. Vanadium, Cr, and Th are associated with aluminosilicate minerals, Ba with carbonate minerals, and Cu, Zn, As, Se, and Pb mainly with sulfide minerals.

Huainan coalfield↗

USGS1966

Isotopic study of galenas from the upper Mississippi Valley, the Illinois-Kentucky, and some Appalachian Valley mineral districts

Analyses of lead isotopes in galena in carbonate rock ore deposits collected from several mineralized districts in the Central and Eastern Interior of the United States support previous studies in establishing that the galena is anomalously radiogenic ("J"type")- This study , using care-fully selected samples to test some géologie relationships, shows region-wide and distrietwide systematic variations in isotope ratios. The genetic implications of thèse variations are discussed. Two mechanisms of origin are considered to explain thèse variations in isotopic ratios. One involves mixing of leads from multiple sources, the other calls for variable lead-isotope ratios originating from a single source. Several source materials for the lead ores have been suggested; whether a single source has predominated, or two or more main sources have predominated is still unresolved. Slopes from Pb206/Pb204 versus Pb207/Pb204 plot are compatible with a contribution of lead by the 1300 ± 300 m.y. basement rocks that underlie the deposits. The spatial relationships of alkaline igneous rocks to several of the minerai districts in the Mississippi Valley région suggest a possible mag-matic source for the lead. Isotopic analyses of galenas closely associated with several of the intrusive rocks are similar in isotopic composition to adjacent ore leads, but genetic implications are ambiguous. Galena oc-curring in shales in the Mississippi Valley région outside mineralized districts contains ordinary lead. Théories that call upon such shales to be the major source of the lead in the depoaits of the Mississippi Valley type must explain this distinct différence in isotopic compositions. Galena collected from districts within the Appalachian Ridge and Valley Province contains notably less radiogenic lead than that from the Mississippi Valley minerai districts , and the lead is of the ordinary type.

Illinois, Kentucky↗

USGS1973

Geology and quality of water in the Modesto-Merced area, San Joaquin Valley, California, with a brief section on hydrology

The Modesto-Merced area includes about 1,800 square miles on the northeast side of the San Joaquin Valley. The physiographic units in the area are (1) Sierra Nevada, (2) dissected uplands, (3) low alluvial plains and fans, (4) river flood plains and channels, and (5) overflow lands. Geologic units consist of consolidated rocks and unconsolidated deposits. The dominant structure of the geologic units is that of a homocline, which reflects the southwestward-tilted fault block of the Sierra Nevada. The consolidated rocks include: (1) basement complex (pre-Tertiary), (2) marine sandstone and shale (Cretaceous), (3) Ione Formation and other sedimentary rocks (Eocene), (4) Valley Springs Formation (late? Miocene), and (5) the Mehrten Formation (Miocene and Pliocene). In the eastern part of the area, the consolidated rocks generally yield small quantities of water to wells except for the Mehrten Formation which is an important aquifer. The unconsolidated deposits include: (1) continental deposits (Pliocene and Pleistocene?), (2) lacustrine and marsh deposits (Pleistocene), (3) older alluvium (Pleistocene and Holocene?), (4) younger alluvium (Holocene), and (5) flood-basin deposits (Holocene). The continental deposits and older alluvium are the main water-yielding units in the unconsolidated deposits. The lacustrine and marsh deposits (E-clay) and the flood-basin deposits yield little water to wells, and the younger alluvium in most places probably yields only moderate quantities of water to wells. There are three ground-water bodies in the Modesto-Merced area: (1) the unconfined water body, (2) the confined water body, and (3) the water body in consolidated rocks. The unconfined water body occurs in the unconsolidated deposits above and east of the E-clay, except in the western and southern parts of the area where clay lenses occur and semiconfined conditions exist. The confined water body occurs in the unconsolidated deposits below the E-clay and extends downward to the base of fresh water. The water body in consolidated rocks occurs under both perched and confined conditions. Ground-water movement in the unconfined and the confined water bodies is generally westward toward the valley trough. In the unconfined water body, the water also moves toward the major rivers, and toward pumping depressions at Modesto and near El Nido. Because of the higher head in the unconfined water body, water slowly moves from it through the E-clay to the underlying confined water body. Surface water is used extensively for irrigation in most of the study area; consequently, shallow water in the unconfined water body has to be controlled by pumping. Nevertheless, water levels near Modesto declined about 6 feet between 1958 and 1962, for the most part during the dry years 1959-61. Near El Nido, water levels declined about 70 feet between 1942 and 1967. In the confined water body, water levels were high in the winter and spring and low in the summer and fall, reflecting irrigation practices. In the southwestern part of the area, water levels in the confined water body declined about 14 feet from 1962 to 1968 and rose slightly after 1968, whereas in the northwestern part water levels remained fairly constant. Water from the upper reaches of the Stanislaus, Tuolumne, Merced, and Chowchilla Rivers is calcium bicarbonate in chemical type and is of excellent quality. As those rivers cross the valley floor, their water quality is generally degraded by return flows from irrigated land, and in the Tuolumne River by saline water discharged from abandoned gas wells. Average dissolvedsolids content in the major rivers, as indicated by chemical analyses, do not exceed 400 mg/1 (milligrams per liter) except in the San Joaquin River where average dissolved-solids content has not exceeded 1,050 mg/l. Water from minor streams in the area is bicarbonate in chemical type with dissolved-solids content ranging from 56 mg/1 to about 350 mg/l. Although chloride-type fresh ground water occurs in the unconfined and confined water bodies and in the water body in consolidated rocks, most of the fresh ground water is a bicarbonate type that has a dissolved-solids content of less than 500 mg/l. Water having dissolved solids in excess of about 2,000 mg/1 is considered to be saline. Saline water extends below the base of fresh water to the basement complex and, except in the extreme eastern part, underlies most of the study area. Saline water also occurs as lenses above the base of fresh water in the unconfined and confined water bodies.

California↗

USGS1989

Seismic methods for determining earthquake source parameters and lithospheric structure

The seismologic methods most commonly used in studies of earthquakes and the structure of the continental lithosphere are reviewed in three main sections: earthquake source parameter determinations, the determination of earth structure using natural sources, and controlled-source seismology. The emphasis in each section is on a description of data, the principles behind the analysis techniques, and the assumptions and uncertainties in interpretation. Rather than focusing on future directions in seismology, the goal here is to summarize past and current practice as a companion to the review papers in this volume. Reliable earthquake hypocenters and focal mechanisms require seismograph locations with a broad distribution in azimuth and distance from the earthquakes; a recording within one focal depth of the epicenter provides excellent hypocentral depth control. For earthquakes of magnitude greater than 4.5, waveform modeling methods may be used to determine source parameters. The seismic moment tensor provides the most complete and accurate measure of earthquake source parameters, and offers a dynamic picture of the faulting process. Methods for determining the Earth’s structure from natural sources exist for local, regional, and teleseismic sources. One-dimensional models of structure are obtained from body and surface waves using both forward and inverse modeling. Forward-modeling methods include consideration of seismic amplitudes and waveforms, but lack the formal resolution estimates obtained with inverse methods. Two- and three-dimensional lithospheric models are derived using various inverse methods, but at present most of these methods consider only traveltimes of body waves. Controlled-source studies of the Earth’s structure are generally divided by method into seismic refraction/wide-angle reflection and seismic reflection studies. Seismic refraction profiles are usually interpreted in terms of two-dimensional structure by forward modeling of traveltimes and amplitudes. The refraction method gives excellent estimates of seismic velocities, but relatively low resolution of structure. Formal resolution estimates are not possible for models derived from forward modeling, but informal estimates can be obtained by perturbing the best-fitting model. Inversion methods for seismic refraction data for one-dimensional models are well established, and two- and three-dimensional methods, including tomography, have recently been developed. Seismic reflection data provide the highest resolution of crustal structure, and have provided many important geological insights in the past decade. The acquisition and processing of these data have been greatly advanced by the hydrocarbon exploration industry. However, reliable crustal velocity control is generally lacking, and the origin of deep crustal reflections remains unclear, resulting in nonunique interpretations. A new form of lithospheric seismology has recently emerged that combines the advantages of seismic refraction and seismic reflection profiles, and the distinction between the two methods is steadily diminishing. Major challenges for future work will be the collection of data that are more densely sampled in space, and the development of interpretation methods that provide quantitative estimates of the uncertainties in the calculated models.

GSA Memoirs↗

USGS1979

Genesis of ore deposits in the San Juan Volcanic Field, Southwestern Colorado-lead isotope evidence

In the San Juan volcanic area of southwestern Colorado, the isotopic composition of lead in ores and ore prospects of Cenozoic age ranges widely: 17.72 to 21.13 for 206 Pb/ 204 Pb; 15.50 to 15.81 for 207 Pb/ 204 Pb; and 37.21 to 38 for 208 Pb/ 204 Pb. Examination of the lead isotope data indicates that once deposition of lead minerals begins, further exchange of lead between fluid and wall rock is insignificant. This conclusion is supported by the relatively constant isotopic composition of the lead in these ores, which is not affected by the grade of ore mineralization or type of wall rock. The values of 206 Pb/ 204 Pb in some vein-type deposits exceed the maximum value known for all Mesozoic and Cenozoic igneous rocks of the Rocky Mountain region. These isotopic relations show that if ore-forming solutions are composed of meteoric water, as indicated in studies of light stable isotopes, they must have penetrated deep enough to acquire lead from Pre-cambrian rocks or sediments derived from them. The fact that some of these vein ores are now in Cenozoic igneous rocks indicates the ore fluid had an upward vertical component to its movement. The lead isotope data therefore support a circulating cell hypothesis for these kinds of ores, as suggested by many recent studies of light stable isotopes as related to mineralization. Some other deposits (Summitville, Jasper, Red Mountain district) have values of 206 Pb/ 204 Pb similar to those of the large volumes of altered rock that enclose them ( 206 Pb/ 204 Pb ∼ 18.5), suggesting that in places the lead may have been locally derived by leaching of the adjacent rocks or from magmatogenic fluids. When the lead isotope data are treated in detail, the rocks and galenas of the Platoro caldera complex, of the central San Juan caklera complex, and of the Baughman Creek center appear to contain significant components derived from 1,400- to l,500-m.y.-old and 1,700- to 1,800 m.y.-old source materials. These also are the ages of the two main groups of rocks that comprise the Precambrian basement under the San Juan volcanic area. Although the data from the western San Juan caldera complex scatter considerably, the only obvious source for the lead seems to be the 1,700- to l,800-m.y.-old rocks or detritus of such age in Phanerozoic sediments. Where the involvement of 1,400- to l,500-m.y.-old sources is greatest, the Th/U ratio in the source material is small (calculated to be about 0.7), whereas the Th/U ratio of the 1,700- to l,800-m.y.-old source material appears to be 2.3 to 3.3. The largest Th/U values are from the western San Juan caldera complex. © 1979 Society of Economic Geologists, Inc.

Colorado↗

USGS1987

Source of lead and mineralizing brines for rossie-type Pb-Zn veins in the Frontenac axis area, New York ( USA).

Veins composed mainly of calcite and some galena, sphalerite, fluorite, and other minerals are widespread in the Frontenac axis area of New York and Ontario. In New York, the veins (Fig. 1) occur mainly west and northwest of Gouverneur (Brown, 1983). The veins, mined in the 1800s for lead, were first described by Emmons (1838). Smyth (1903) called these the "Rossie lead veins," a name now used locally for all veins of this type. Similar veins in southeastern Ontario were described by Uglow (1916) and Sangster (1970). The steeply dipping veins are aligned along extensional fractures in metamorphic rocks of the Grenville Complex and in Paleozoic sedimentary rocks, including the Potsdam Sandstone of Late Cambrian age, and limestones as young as Middle Ordovician. However, the age of emplacement of Rossie veins is unknown. The veins are mineralogically simple, consisting of calcite (~95%) with minor and approximately equal amounts of sphalerite and galena, and sparse fluorite, barite, celestite, and chalcopyrite (Brown, 1983). Paragenetically early minerals are crushed and granulated; later undeformed minerals fill open spaces (Fig. 2). Sandstone dikes that originated from either the overlying Potsdam Sandstone or stratigraphically higher arenaceous rocks cut into the Rossie veins and occupy all available space. Their unstratified nature suggests that sand was intruded under high hydraulic pressure during tectonic events that reopened the veins. Most veins are vertical and narrow (1-3 cm wide) and those that were mined are as much as 1.7 m wide. The veins trend mainly northwest-southeast but have a local east-west orientation. The fractures and veins show evidence of strike-slip faulting with a right-lateral offset due to late reactivation of north-east-trending faults that originally formed during the Proterozoic Grenville orogeny. Relatively rare inclined veins, termed gash veins (Brown, 1983), occur in proximity to some of the regional northeast-trending faults. These veins contain open spaces lined with large, undeformed crystals of calcite (~90%) and green fluorite (~5%). The minerals of the northeast-trending gash veins, which dip to the northwest, are believed to be paragenetically late results of the same mineralization and tectonic event that produced the Rossie veins. For example, the green fluorite in the gash veins is similar in color and occurrence to small fluorite crystals in vugs in the vertical Rossie veins. Associated with the fluorite in both occurrences is coarse crystalline calcite containing tiny tetrahedra of chalcopyrite aligned along crystallographic planes. The present study of fluid inclusions and lead isotopes was done to understand better the nature and possible source of the mineralizing solutions for both vertical and gash veins and the possible origin of the lead and zinc mineralization. Large deposits of essentially syngenetic sphalerite with minor to trace galena occur in the Proterozoic rocks of this region (e.g., Balmat-Edwards, New York). Although none of these deposits are known in the immediate vicinity of Rossie veins, the possibility that Rossie veins contain remobilized metals from these older deposits was considered.

New York↗

USGS2006

Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan

This report presents an overview of the geology, hydrology, and climate of the lower Helmand Basin, a large, closed, arid basin in southern Afghanistan. The basin is drained by the Helmand River, the only perennial desert stream between the Indus and Tigris-Euphrates Rivers. The Helmand River is the lifeblood of southern Afghanistan and has supported desert civilizations in the Sistan depression for over 6,000 years. The Helmand Basin is a structurally closed basin that began to form during the middle Tertiary as a consequence of the collision of several Gondwanaland fragments. Aeromagnetic studies indicate the basin is 3-5 kilometers deep over basement rocks. Continued subsidence along basin-bounding faults in Iran and Pakistan throughout the Neogene has formed the Sistan depression in the southwest corner of the basin. Lacustrine, eolian, and fluvial deposits are commonly exposed in the basin and were intruded by latest Miocene-middle Quaternary volcanoes, which indicates that depositional environments in the lower Helmand Basin have not substantially changed for nearly 10 million years. Lakes expanded in the Sistan depression during the Quaternary; however, the size and extent of these pluvial lakes are unknown. Climate conditions in the lower Helmand Basin likely mirrored climate changes in the Rajasthan Desert to the east and in Middle Eastern deserts to the west: greater aridity during global episodes of colder temperatures and increased available moisture during episodes of warmer temperatures. Eolian processes are unusually dominant in shaping the landscape in the basin. A strong wind blows for 120 days each summer, scouring dry lakebeds and creating dune fields from annual flood deposits. Nearly one-third of the basin is mantled with active or stabilized dunes. Blowing winds combined with summer temperatures over 50? Celsius and voluminous insect populations hatched from the deltaic wetlands create an environment referred to as the 'most odious place on earth' by 19th century visitors. During dry years, large plumes of dust originating from Sistan are recorded by weather satellites. The Helmand River drains about 40 percent of Afghanistan and receives most of its moisture from melting snow and spring storms. Similar to many desert streams, the Helmand and its main tributary, the Arghandab River, are characterized by large fluctuations in monthly and annual discharges. Water from the Helmand accumulates in several hamuns (shallow lakes) in the Sistan depression. The wetlands surrounding these hamuns are the largest in western Asia and are directly affected by droughts and floods on the Helmand. Average annual discharge on the Helmand is about 6.12 million megaliters (million cubic meters), and the annual discharge varies by a factor of five. In 2005, the region was just beginning to recover from the longest drought (1998-2005) of record back to 1830. Annual peak discharges range from less than 80 cubic meters per second in 1971 to nearly 19,000 cubic meters per second in 1885. Large floods fill each hamun to overflowing to create one large lake that overflows into the normally dry Gaud-i Zirreh basin. The interaction of flooding, active subsidence, and wind erosion causes frequent channel changes on the Helmand delta. A major development effort on the Helmand River was initiated after World War II with substantial aid from the United States. Two dams and several major canals were completed in the 1950s; however, poor drainage conditions on the newly prepared agricultural fields caused extensive waterlogging and salinization. New drains were installed and improved agricultural methods were implemented in the 1970s, and some lands became more productive. Since 1980, Afghanistan has endured almost constant war and civil and political strife. In 2005, the country was on a path to rebuild much of its technical infrastructure. Revitalization of agricultural lands in the lower Helmand Basin and improved managem

Scientific Investigations Report↗

USGS2006

Hydrology and water quality in the Green River and surrounding agricultural areas near Green River in Emery and Grand Counties, Utah, 2004-05

Water from the Colorado River and its tributaries is used for municipal and industrial purposes by about 27 million people and irrigates nearly 4 million acres of land in the Western United States. Water users in the Upper Colorado River Basin consume water from the Colorado River and its tributaries, reducing the amount of water in the river. In addition, application of water to agricultural land within the basin in excess of crop needs can increase the transport of dissolved solids to the river. As a result, dissolved-solids concentrations in the Colorado River have increased, affecting downstream water users. During 2004-05, the U.S. Geological Survey, in cooperation with the Natural Resources Conservation Service, investigated the occurrence and distribution of dissolved solids in water from the agricultural areas near Green River, Utah, and in the adjacent reach of the Green River, a principle tributary of the Colorado River. The flow-weighted concentration of dissolved solids diverted from the Green River for irrigation during 2004 and 2005 was 357 milligrams per liter and the mean concentration of water collected from seeps and drains where water was returning to the river during low-flow conditions was 4,170 milligrams per liter. The dissolved-solids concentration in water from the shallow part of the ground-water system ranged from 687 to 55,900 milligrams per liter. Measurable amounts of dissolved solids discharging to the Green River are present almost exclusively along the river banks or near the mouths of dry washes that bisect the agricultural areas. The median dissolved-solids load in discharge from the 17 drains and seeps visited during the study was 0.35 ton per day. Seasonal estimates of the dissolved-solids load discharging from the study area ranged from 2,800 tons in the winter to 6,400 tons in the spring. The estimate of dissolved solids discharging from the study area annually is 15,700 tons. Water samples collected from selected sites within the Green River agricultural areas were analyzed for naturally occurring isotopes of strontium and boron, which can be useful for differentiating dissolved-solids sources. Substantial variations in the delta strontium-87 and delta boron-11 values among the sites were measured. Canal and river samples had relatively low concentrations of strontium and the most positive (heavier) isotopic ratios, while drains and seeps had a wide range of strontium concentrations and isotopic ratios that generally were less positive (lighter). Further study of the variation in strontium and boron concentrations and isotope ratios may provide a means to distinguish end members and discern processes affecting dissolved solids within the Green River study area; however, the results from isotope data collected during this study are inconclusive. Flow and seepage losses were estimated for the three main canals in the study area for May 2 to October 4 in any given year. This period coincides with the frost-free period in the Green River area. Estimated diversion from the Green River into the Thayn, East Side, and Green River Canals is 6,600, 6,070, and 19,900 acre-feet, respectively. The estimated seepage loss to ground water from the Thayn, East Side, and Green River Canals during the same period is 1,550, 1,460, and 4,710 acre-feet, respectively.

Utah↗

USGS1999

Predicting ground-water movement in large mine spoil areas in the Appalachian Plateau

Spoil created by surface mining can accumulate large quantities of ground-water, which can create geotechnical or regulatory problems, as well as flood active mine pits. A current study at a large (4.1 km2), thick, (up to 90 m) spoil body in eastern Kentucky reveals important factors that control the storage and movement of water. Ground-water recharge occurs along the periphery of the spoil body where surface-water drainage is blocked, as well as from infiltration along the spoil-bedrock contact, recharge from adjacent bedrock, and to a minor extent, through macropores at the spoil's surface. Based on an average saturated thickness of 6.4 m for all spoil wells, and assuming an estimated porosity of 20%, approximately 5.2 x 106 m3 of water is stored within the existing 4.1 km2 of reclaimed spoil. A conceptual model of ground-water flow, based on data from monitoring wells, dye-tracing data, discharge from springs and ponds, hydraulic gradients, chemical data, field reconnaissance, and aerial photographs indicate that three distinct but interconnected saturated zones have been established: one in the spoil's interior, and others in the valley fills that surround the main spoil body at lower elevations. Ground-water movement is sluggish in the spoil's interior, but moves quickly through the valley fills. The conceptual model shows that a prediction of ground-water occurrence, movement, and quality can be made for active or abandoned spoil areas if all or some of the following data are available: structural contour of the base of the lowest coal seam being mined, pre-mining topography, documentation of mining methods employed throughout the mine, overburden characteristics, and aerial photographs of mine progression.Spoil created by surface mining can accumulate large quantities of ground-water, which can create geotechnical or regulatory problems, as well as flood active mine pits. A current study at a large (4.1 km2), thick, (up to 90 m) spoil body in eastern Kentucky reveals important factors that control the storage and movement of water. Ground-water recharge occurs along the periphery of the spoil body where surface-water drainage is blocked, as well as from infiltration along the spoil-bedrock contact, recharge from adjacent bedrock, and to a minor extent, through macropores at the spoil's surface. Based on an average saturated thickness of 6.4 m for all spoil wells, and assuming an estimated porosity of 20%, approximately 5.2 ?? 106 m3 of water is stored within the existing 4.1 km2 of reclaimed spoil. A conceptual model of ground-water flow, based on data from monitoring wells, dye-tracing data, discharge from springs and ponds, hydraulic gradients, chemical data, field reconnaissance, and aerial photographs indicate that three distinct but interconnected saturated zones have been established: one in the spoil's interior, and others in the valley fills that surround the main spoil body at lower elevations. Ground-water movement is sluggish in the spoil's interior, but moves quickly through the valley fills. The conceptual model shows that a prediction of ground-water occurrence, movement, and quality can be made for active or abandoned spoil areas if all or some of the following data are available: structural contour of the base of the lowest coal seam being mined, pre-mining topography, documentation of mining methods employed throughout the mine, overburden characteristics, and aerial photographs of mine progression.

International Journal of Coal Geology↗

USGS2001

Surficial geologic map of the greater Omaha area, Nebraska and Iowa

Geologic mapping, in support of the USGS Omaha-Kansas City Geologic Mapping Project, shows the spatial distribution of artificial-fill, alluvial, eolian, and glacial deposits and bedrock in and near Omaha, Nebraska. Artificial fill deposits are mapped chiefly beneath commercial structures, segments of interstate highways and other major highways, railroad tracks, airport runways, and military facilities, and in landfills and earth fills. Alluvial deposits are mapped beneath flood plains, in stream terraces, and on hill slopes. They include flood-plain and stream-channel alluvium, sheetwash alluvium, and undivided sheetwash alluvium and stream alluvium. Wind-deposited loess forms sheets that mantle inter-stream areas and late Wisconsin terrace alluvium. Peoria Loess is younger of the two loess sheets and covers much of the inter-stream area in the map area. Loveland Loess is older and is exposed in a few small areas in the eastern part of the map area. Glacial deposits are chiefly heterogeneous, ice-deposited, clayey material (till) and minor interstratified stream-deposited sand and gravel. Except for small outcrops, glacial deposits are covered by eolian and alluvial deposits throughout most of the map area. Bedrock is locally exposed in natural exposures along the major streams and in quarries. It consists of Dakota Sandstone and chiefly limestone and shale of the Lansing and Kansas City Groups. Sand and gravel in flood plain and stream-channel alluvium in the Platte River valley are used mainly for concrete aggregate. Limestone of the Lansing and Kansas City Groups is used for road-surfacing material, rip rap, and fill material.

Iowa, Nebraska↗

USGS2018

Combining sediment fingerprinting with age-dating sediment using fallout radionuclides for an agricultural stream, Walnut Creek, Iowa, USA

Purpose The main purpose of this study was to demonstrate the utility of the sediment fingerprinting approach to apportion surface-derived sediment, and then age date that portion using short-lived fallout radionuclides. In systems where a large mass of mobile sediment is in channel storage, age dating provides an understanding of the transfer of sediment through the watershed and the time scales over which management actions to reduce sediment loadings may be effective. Materials and methods In the agricultural Walnut Creek watershed, Iowa, the sediment-fingerprinting approach with elemental analysis was used to apportion the sources of fine-grained sediment (croplands, prairie, unpaved roads, and channel banks). Fallout radionuclides ( 7 Be, 210 Pb ex ) were used to age the portion of suspended sediment that was derived from agricultural topsoil. Age dating was performed at two different scales: 210 Pb ex which can date sediment to ~ 85 years and 7 Be to ~ 1 year. Results and discussion Sediment fingerprinting results indicated that the majority of suspended sediment is derived from cropland (62%) with streambanks contributing 36%, and prairie, pasture, and unpaved roads each contributing ≤ 1%. The topsoil–derived portion of sediment (primarily agriculture) dated using 210 Pb ex has ages ranging from 1 to 58 years, and using 7 Be, a component of much younger sediment that yields ages ranging from 44 to 205 days. The occurrence of 7 Be indicates that some portion of the sediment is young, on the order of months, whereas the dating based on 210 Pb ex indicates that some of the surface-derived sediment has been in channel storage for decades. Published studies in Walnut Creek indicate that a large component of sediment is stored in the channel bed. Conclusions We conclude that the 210 Pb ex -based ages are a reasonable estimate for the mean age of the surface-derived fraction and that 7 Be activities are evidence that there is a smaller fraction of very young sediment in the stream. We propose a geomorphic model where agricultural soil is delivered to the channel and conveyed to the watershed outlet at three time scales: a geologic-millennial time scale, decades, and a young time scale (< 1 year).

Iowa↗

USGS2011

Well installation, single-well testing, and particle-size analysis for selected sites in and near the Lost Creek Designated Ground Water Basin, north-central Colorado, 2003-2004

This report describes results from a groundwater data-collection program completed in 2003-2004 by the U.S. Geological Survey in support of the South Platte Decision Support System and in cooperation with the Colorado Water Conservation Board. Two monitoring wells were installed adjacent to existing water-table monitoring wells. These wells were installed as well pairs with existing wells to characterize the hydraulic properties of the alluvial aquifer and shallow Denver Formation sandstone aquifer in and near the Lost Creek Designated Ground Water Basin. Single-well tests were performed in the 2 newly installed wells and 12 selected existing monitoring wells. Sediment particle size was analyzed for samples collected from the screened interval depths of each of the 14 wells. Hydraulic-conductivity and transmissivity values were calculated after the completion of single-well tests on each of the selected wells. Recovering water-level data from the single-well tests were analyzed using the Bouwer and Rice method because test data most closely resembled those obtained from traditional slug tests. Results from the single-well test analyses for the alluvial aquifer indicate a median hydraulic-conductivity value of 3.8 x 10-5 feet per second and geometric mean hydraulic-conductivity value of 3.4 x 10-5 feet per second. Median and geometric mean transmissivity values in the alluvial aquifer were 8.6 x 10-4 feet squared per second and 4.9 x 10-4 feet squared per second, respectively. Single-well test results for the shallow Denver Formation sandstone aquifer indicate a median hydraulic-conductivity value of 5.4 x 10-6 feet per second and geometric mean value of 4.9 x 10-6 feet per second. Median and geometric mean transmissivity values for the shallow Denver Formation sandstone aquifer were 4.0 x 10-5 feet squared per second and 5.9 x 10-5 feet squared per second, respectively. Hydraulic-conductivity values for the alluvial aquifer in and near the Lost Creek Designated Ground Water Basin generally were greater than hydraulic-conductivity values for the Denver Formation sandstone aquifer and less than hydraulic-conductivity values for the alluvial aquifer along the main stem of the South Platte River Basin reported by previous studies. Particle sizes were analyzed for a total of 14 samples of material representative of the screened interval in each of the 14 wells tested in this study. Of the 14 samples collected, 8 samples represent the alluvial aquifer and 6 samples represent the Denver Formation sandstone aquifer in and near the Lost Creek Designated Ground Water Basin. The sampled alluvial aquifer material generally contained a greater percentage of large particles (larger than 0.5 mm) than the sampled sandstone aquifer material. Alternatively, the sampled sandstone aquifer material generally contained a greater percentage of fine particles (smaller than 0.5 mm) than the sampled alluvial aquifer material consistent with the finding that the alluvial aquifer is more conductive than the sandstone aquifer in the vicinity of the Lost Creek Designated Ground Water Basin.

Open-File Report↗

USGS2014

Selenium in the upper Blackfoot River watershed, southeastern Idaho, 2001-12

The upper Blackfoot River in southeastern Idaho receives runoff from 12 large phosphate mines. Waste shales that are removed to access the phosphate ore are highly enriched with selenium, resulting in elevated selenium in runoff from the mine waste dumps. In 2001, in cooperation with the Bureau of Land Management, the U.S. Geological Survey (USGS) began monitoring streamflow, selenium, and other water-quality parameters at a single location near the outlet of the upper Blackfoot River to the Blackfoot Reservoir. Water samples primarily were collected by a flow triggered, automated pump sampler, supplemented by manual point and equal-width integrated manual samples. The approach to monitoring concentrations and streamflow over time at a fixed location is ideal for evaluating temporal trends, but provides no information about the relative source contributions from the mine waste dumps draining into various tributaries. In 2001, the Idaho Department of Environmental Quality (IDEQ) began an annual, mid-May, synoptic survey of selenium concentrations and streamflow at 21 locations along the main stem Blackfoot River and its tributaries. Individually, neither the intensive USGS sampling at the outlet nor the IDEQ annual synoptic sampling provides a comprehensive view of selenium runoff in the Blackfoot River watershed. Together, the efforts are complementary; therefore, in this report, results are presented from both sampling efforts. The USGS collected time-series data from 2001 to 2012 at a fixed location, the Blackfoot River near the outlet of the reservoir, near Henry, Idaho (USGS streamgage 13063000). Dissolved selenium concentrations from 450 filtered samples collected at this site ranged from 0.5 to 11.4 micrograms per liter (μg/L). The State of Idaho chronic aquatic life criterion concentration of 5 μg/L was exceeded in 31 percent of the samples, with most exceedances occurring during May of each year. No exceedances of the selenium criterion were recorded in months other than April, May, or June. Concentrations of selenium in unfiltered and filtered samples were similar, and concentrations from samples collected by depth and width integrated methods were similar to those collected by grab (point) samples, indicating that the grab samples adequately represent selenium concentrations across the entire river cross section. In speciation analyses made during 2003 and 2004, the median percentage of total selenium as selenate was 81 percent, ranging from 17 to 98 percent, and the median percentage of total selenium as selenite was 19 percent, ranging from 2 to 83 percent of the total selenium. During the period of study, selenium concentrations had an upward trend during the lowflow season of August–October. Time trends were not obvious during other seasons. Selenium daily loads varied by more than a factor of 900 during the study period and ranged from 0.03 kilograms per day (kg/d) to more than 24 kg/d. Annual maximum daily loads of selenium varied over nearly a factor of 12, ranging from about 2 to 24 kg/d. For the annual spring synoptic samples collected by the IDEQ along the main stem Blackfoot River and major tributaries, selenium concentrations ranged from less than 2 to 870 μg/L in 176 samples. In most years, the synoptic sampling showed that the majority of the selenium loads passing the USGS streamgage at the outlet of the watershed could be attributed to a single tributary, East Mill Creek, which enters the Blackfoot River through Spring Creek. Selenium loads decreased by about half from East Mill Creek before reaching the Blackfoot River, suggesting that much selenium is at least temporarily removed from the water column by uptake by aquatic vegetation or by losses to sediment. Similar decreases in selenium loads occurred through the main stem Blackfoot River before reaching the outlet in low flow years, but not in high flow years.

Idaho↗