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At least 1,783 records · Page 99Linked to original sources

Shallow Groundwater Movement in the Skagit River Delta Area, Skagit County, Washington

Shallow groundwater movement in an area between the lower Skagit River and Puget Sound was characterized by the U.S. Geological Survey to assist Skagit County and the Washington State Department of Ecology with the identification of areas where water withdrawals from existing and new wells could adversely affect streamflow in the Skagit River. The shallow groundwater system consists of alluvial, lahar runout, and recessional outwash deposits composed of sand, gravel, and cobbles, with minor lenses of silt and clay. Upland areas are underlain by glacial till and outwash deposits that show evidence of terrestrial and shallow marine depositional environments. Bedrock exposures are limited to a few upland outcrops in the southwestern part of the study area, and consist of metamorphic, sedimentary, and igneous rocks. Water levels were measured in 47 wells on a quarterly basis (August 2007, November 2007, February 2008, and May 2008). Measurements from 34 wells completed in the shallow groundwater system were used to construct groundwater-level and flow-direction maps and perform a linear-regression analysis to estimate the overall, time averaged shallow groundwater-flow direction and gradient. Groundwater flow in the shallow groundwater system generally moves in a southwestward direction away from the Skagit River and toward the Swinomish Channel and Skagit Bay. Local groundwater flow towards the river was inferred during February 2008 in areas west and southwest of Mount Vernon. Water-level altitudes varied seasonally, however, and generally ranged from less than 3 feet (August 2007) in the west to about 15 feet (May 2008) in the east. The time-averaged, shallow groundwater-flow direction derived from regression analysis, 8.5 deg south of west, was similar to flow directions depicted on the quarterly water-level maps. Seasonal changes in groundwater levels in most wells in the Skagit River Delta follow a typical pattern for shallow wells in western Washington. Water levels rise from October through March, when precipitation is high, and decline from April through September, when precipitation is lower. Groundwater levels in wells along the eastern margin of the study area also are likely influenced by stage on the Skagit River. Water levels in these wells remained elevated through April, and did not seem to begin to decline until the end of May in response to declining river stage. Groundwater levels in a well equipped with a continuous water-level recorder exhibited periodic fluctuations that are characteristic of ocean tides. This well is less than 1 mile east of the tidally influenced Swinomish Channel, and exhibited water-level fluctuations that correspond closely to predicted tidal extremes obtained from a tide gage near La Conner, Washington.

Scientific Investigations Report↗

Hydrogeology of a Biosolids-Application Site Near Deer Trail, Colorado, 1993-99

This report presents hydrogeology data and interpretations resulting from two studies related to biosolids applications at the Metro Wastewater Reclamation District property near Deer Trail, Colorado, done by the U.S. Geological Survey in cooperation with the Metro Wastewater Reclamation District: (1) a 1993-99 study of hydrology and water quality for the Metro Wastewater Reclamation District central property and (2) a 1999 study of regional bedrock-aquifer structure and local ground-water recharge. Biosolids were applied as a fertilizer during late 1993 through 1999. The 1993 Metro Wastewater Reclamation District property boundary constitutes the study area, but hydrogeologic structure maps for a much larger area are included in the report. The study area is located on the eastern margin of the Denver Basin, a bowl-shaped sequence of sedimentary rocks. The uppermost bedrock formations in the vicinity of the study area consist of the Pierre Shale, the Fox Hills Sandstone, and the Laramie Formation, parts of which comprise the Laramie-Fox Hills hydrostratigraphic unit and thus, where saturated, the Laramie-Fox Hills aquifer. In the vicinity of the study area, the Laramie-Fox Hills hydrostratigraphic unit dips gently to the northwest, crops out, and is partially eroded. The Laramie-Fox Hills aquifer is either absent or not fully saturated within the Metro Wastewater Reclamation District properties, although this aquifer is the principal aquifer used for domestic supply in the vicinity of the study area. Yield was small from two deep monitoring wells in the Laramie-Fox Hills aquifer within the study area. Depth to water in these wells was about 110 and 150 feet below land surface, and monthly water levels fluctuated 0.5 foot or less. Alluvial aquifers also are present in the unconsolidated sand and loess deposits in the valleys of the study area. Interactions of the deeper parts of the Laramie-Fox Hills aquifer with shallow ground water in the study area include a general close hydraulic connection between alluvial and bedrock aquifers, recharge of the Cottonwood Creek and much of the Muddy Creek alluvial aquifers by the bedrock aquifer, and possible recharge of the bedrock aquifer by a Rattlesnake Creek tributary. Some areas of shallow ground water were recharged by infiltration from rain or ponds, but other areas likely were recharged by other ground water. Data for shallow ground water indicate that ground-water recharge takes less than a day at some sites to about 40 years at another site. Depth to shallow ground water in the study area ranged from about 2 feet to about 37 feet below land surface. Shallow ground-water levels likely were affected by evapotranspiration. Ground water is present in shallow parts of the bedrock aquifer or in alluvial aquifers in four drainage basins: Badger Creek, Cottonwood Creek, Muddy Creek, and Rattlesnake Creek. These drainage basins generally contained only ephemeral streams, which flow only after intense rain.

Water-Resources Investigations Report↗

Enhancing mineral systems exploration through geochronology, thermochronology, and isotope analysis: USGS Geochron and USGS Isotope databases

A mineral systems approach to mineral exploration provides a comprehensive framework for understanding ore deposit formation by examining the geodynamic, magmatic, hydrothermal, and sedimentary processes responsible for mineralization, alteration, and remobilization of economic mineral deposits. Temporal and thermal constraints on ore genesis are crucial for refining mineral system models and guiding predictive exploration strategies. Geochronology and thermochronology offer invaluable insights into the timing and thermal evolution of ore-forming processes, whereas isotopic analyses provide critical information on the source and geochemical history of ore-forming fluids. Combining these methodologies have proven highly effective for mineral exploration in regions like Australia, however, their combined application has been limited in the United States. To apply these tools to mineral systems-based exploration, the U.S. Geological Survey (USGS) has developed two products: (1) The USGS Geochron Database, and (2) the USGS Isotope Database. These databases provide centralized repositories of geo/thermochronological dates and data (Geochron Database) and both radiogenic and stable isotope data (Isotope Database) generated by the USGS and partners over the past decades. Integrating these datasets together and with traditional exploration approaches provides the mineral exploration community with powerful tools for determining the temporal and thermal histories of ore systems and identifying metallogenic source provinces.

Continental United States↗

Geology and ore deposits of the Uncompahgre (Ouray) Mining District, Southwestern Colorado

The Uncompahgre mining district, part of the Ouray mining district, includes an area of about 15 mi 2 on the northwestern flank of the San Juan Mountains in southwestern Colorado from which ores of gold, silver, copper, lead, and zinc have had a gross value of $14 to 15 million. Bedrock within the district ranges in age from Proterozoic to Cenozoic. At least three major uplifts of the ancestral San Juan Mountains occurred during the Proterozoic and at the close of the Paleozoic and Mesozoic, respectively. The last event, known as the Laramide orogeny, locally was accompanied by extensive intrusion of igneous rocks. The principal ore deposits of the district were associated with crosscutting and laccolithic intrusions of porphyritic granodiorite formed during the Laramide orogeny. The ores were deposited chiefly in Paleozoic and Mesozoic sedimentary strata. Ore deposits range from low-grade, contact-metamorphic through pyritic base-metal bodies containing silver and gold tellurides and native gold to silver-bearing lead-zinc deposits. Ore deposition was largely controlled by structural trends and axes of uplift established during Paleozoic deformation, and also in part by structural lines established during the Proterozoic. There are two main structural axes in the district: (1) a north-northwest-trending axis of uplift, called the Uncompahgre axis, and (2) an intrusive axis of northeastward trend. The two axes intersect near the center of eruptive activity and divide the district into four structural sectors. Sources of the ore-forming fluids lie along the northeast-trending intrusive zone and appear to be related genetically to the igneous rocks. Contact-metamorphic deposits and most of the pyritic gold-bearing deposits were found in the central parts of the district. The silver-lead-zinc deposits were found chiefly in the northern and southern sectors of the district. Ore deposition was controlled by nearness to the intrusive contacts, nearness to zones of shallow tensional fractures, and other factors. The largest and highest grade deposits were either mostly developed or nearly exhausted at the time of our studies; they occurred in a zone near the Uncompahgre axis.

Colorado↗

Seismological and geodetic constraints on the 2011 M w 5.3 Trinidad, Colorado earthquake and induced deformation in the Raton Basin

The Raton Basin of southern Colorado and northern New Mexico is an actively produced hydrocarbon basin that has experienced increased seismicity since 2001, including the August 2011 M w 5.3 Trinidad normal faulting event. Following the 2011 earthquake, regional seismic observations were used to relocate 21 events, including the 2011 main shock, two foreshocks, and 13 aftershocks. Additionally, interferometric synthetic aperture radar (InSAR) observations of both the 2011 event and preevent basin deformation place constraint on the spatial kinematics of the 2011 event and localized basin subsidence due to ground water or gas withdrawal. We find that the 2011 earthquake ruptured an 8–10 km long segment of a normal fault at depths of 1.5–6.0 km within the crystalline Precambrian basement underlying the Raton Basin sedimentary rocks. The earthquake also nucleated within the crystalline basement in the vicinity of an active wastewater disposal site. The ensuing aftershock sequence demonstrated statistical properties expected for intraplate earthquakes, though the length of the 2011 earthquake is unexpectedly long for an M w 5.3 event, suggesting that wastewater disposal may have triggered a low stress drop, otherwise natural earthquake. Additionally, preevent and postevent seismicity in the Raton Basin spatially correlates to regions of subsidence observed in InSAR time series analysis. While these observations cannot discern a causal link between hydrocarbon production and seismicity, they constrain spatial relationships between active basin deformation and geological and anthropogenic features. Furthermore, the InSAR observations highlight the utility of space-based geodetic observations for monitoring and assessing anthropogenically induced and triggered deformation.

Journal of Geophysical Research B: Solid Earth↗

USGS east-coast sediment analysis: Procedures, database, and GIS data

Preface Sediments off the eastern United States vary markedly in texture - the size, shape, and arrangement of their grains. For descriptive purposes, however, it is typically most useful to classify these sediments according to their grain-size distributions. Starting in 1962, the U.S. Geological Survey (USGS) and the Woods Hole Oceanographic Institution (WHOI) began a joint program to study the marine geology of the continental margin off the Atlantic coast of the United States. As part of this program and numerous subsequent projects, thousands of sediment samples were collected and analyzed for grain size. This report describes the field methods used to collect marine sediment sample, the laboratory methods used to determine and characterize grain-size distributions, and presents these data in several formats that can be readily employed by interested parties. By entering data into usSEABED, a large data compilation and mining program (Reid and others, 2005), this study also responds to an increasing demand for regional information on sea-floor sedimentary character with applications to aggregate resources suitable for beach nourishment and coastal restoration, benthic habitat mapping, and sediment transport studies. To this end, the report is divided into three sections: the first discusses field and laboratory procedures, the second contains the grain-size data, and the third provides a GIS data catalog that lists the available data layers and FGDC-compliant metadata.

Open-File Report↗

Database of recent tsunami deposits

This report describes a database of sedimentary characteristics of tsunami deposits derived from published accounts of tsunami deposit investigations conducted shortly after the occurrence of a tsunami. The database contains 228 entries, each entry containing data from up to 71 categories. It includes data from 51 publications covering 15 tsunamis distributed between 16 countries. The database encompasses a wide range of depositional settings including tropical islands, beaches, coastal plains, river banks, agricultural fields, and urban environments. It includes data from both local tsunamis and teletsunamis. The data are valuable for interpreting prehistorical, historical, and modern tsunami deposits, and for the development of criteria to identify tsunami deposits in the geologic record.

Open-File Report↗

Geologic map of metallic and nonmetallic mineral deposits, Badakhshan Province, Afghanistan, modified from the 1967 original map compilation of G.G. Semenov and others

This geologic map of central Badakhshan Province, Afghanistan, is a combined, redrafted, and modified version of the Geological map of central Badakhshan, scale 1:200,000 (sheet 217), and Map of minerals of central Badakhshan, scale 1:200,000 (also sheet 217) from Semenov and others (1967) (Soviet report no. R0815). That unpublished Soviet report contains the original maps and cross sections, which were prepared in cooperation with the Ministry of Mines and Industries of the Republic of Afghanistan in 1967 under contract no. 1378 (Technoexport, USSR). This USGS publication also includes the gold metallogeny summarized in Abdullah and others (1977) and Peters and others (2007, 2011), and additional compilations from Guguev and others (1967). Badakhshan Province consists of volcanic, sedimentary, and metamorphic rocks of various ages from late Proterozoic to Cenozoic. The rocks are intensively dislocated and cut by intrusions of magmatic rocks. Primary gold occurrences are distinguished in shear zones with hydrothermal alterations or in contact-metasomatic rocks near magmatic intrusions.

Badakhshan↗

Age of the Morton and Montevideo gneisses and related rocks, southwestern Minnesota

Granitic gneisses in the vicinities of Morton and Montevideo in the Minnesota River Valley are dated at 3550 m.y. ago and are the oldest rocks so far found in North America. The gneisses were altered in varying degree by younger events of which two have been dated at 2650 m.y. and 1850 m.y. old. The event which occurred 2650 m.y. ago was a high-grade metamorphism accompanied by the intrusion of a large volume of granitic magma. Only the U-Pb zircon and the Rb-Sr whole-rock ages survived this event, and both types are discordant. A two-stage model that explains the U-Pb discordant ages combines a primary discordance produced during the metamorphism of 2650 m.y. ago with a secondary discordance developed approximately 100 m.y. ago when uplift and erosion brought the rocks close to the surface. This secondary discordance is also shown by the zircon from granite near Sacred Heart (2650 m.y. old) and from a younger granitic pluton (1850 m.y. old) near Granite Falls. The discordance in the Rb-Sr whole-rock ages is attributed primarily to the loss of radiogenic Sr 87 that probably occurred largely during the metamorphism of 2650 m.y. ago. Some later loss, however, is indicated in the younger ages of biotite and K-feldspar. Granitic material introduced or mobilized during the metamorphism is also a complicating factor. The 1850-m.y.-ago event was a low-grade metamorphism that reset the K-Ar and Rb-Sr ages of biotite in the rocks between Granite Falls and Ortonville. A number of small plutons, ranging in composition from gabbro to granite, and basaltic dikes were emplaced in the gneisses at this time, but only the granitic pluton near Granite Falls has been dated by both U-Pb and Rb-Sr methods. The mineral ages show variations that are difficult to explain, and the low apparent ages of the biotite may be in some way related to epeirogeny and the stabilizing of the K-Ar and Rb-Sr systems. The southeastern part of the valley, underlain by the Morton Gneiss and the granite at Sacred Heart, was stabilized 2400 to 2600 m.y. ago, but the northwestern part, underlain by gneiss in the Granite Falls-Montevideo area and by granite in the Ortonville area, was not stabilized until 1700 to 1850 m.y. ago. The Morton Gneiss was formed by synkine-matic intrusions of trondhjemitic and granitic magmas, and the structure dates back to the time of the intrusions, 3550 m.y. ago. A similar origin as a synkinematic intrusion of granite is favored to explain the gneiss at Montevideo. The country rock appears to have been a layered series of basaltic lavas, sedimentary rocks, and possibly some sill-like masses of diabase or gabbro. The structure of the region probably was considerably modified during the high-grade metamorphism 2650 m.y. ago. The rock types that were involved in the Mortonian event 3550 m.y. ago are similar to more recent crustal rocks and do not represent a protocrust.

Minnesota↗

Water-quality assessment of part of the Upper Mississippi River basin, Minnesota and Wisconsin: Environmental setting and study design

The Upper Mississippi River Basin is diverse in ways that can control the areal distribution and flow of water and the distribution and concentration of constituents that affect water quality. A review of the environmental setting of the Upper Mississippi River Basin study unit of the National Water-Quality Assessment Program is intended to put water quality in perspective with the geology, soils, climate, hydrology, ecology and historical uses of the land and provides a basis for the sampling design of the study. The Upper Mississippi River Basin study unit encompasses about 47,000 square miles and includes all of the basin upstream from Lake Pepin. The climate of the study unit is subhumid continental with cold dry winters and warm, moist summers. Average annual precipitation ranges from 22 inches in the western part of the study unit to 32 inches in the east. Annual runoff ranges from less than 2 inches in the west to 14 inches in the northeast. The physiography of the study unit includes the Superior Upland and the Central Lowland Provinces. The Wisconsin Driftless Area and the Dissected Till Plains are unique physiographic sections of the Central Lowland Province. Hydrogeologic units in glacial deposits include surficial and buried sand and gravel aquifers and confining units. Bedrock aquifers and confining units are part of a thick sequence of sedimentary rocks that can be divided into major aquifers separated by confining units. The population of the study unit was about 3,640,000 as of 1990 and increased 16 percent between 1970 and 1990. Seventy-five percent of the population lives in the Twin Cities metropolitan area. An average of 413 million gallons of water per day was used 59 percent from ground water and 41 percent from surface water. Land use and land cover in the study unit consists of forested, agricultural, and urban areas. About 63 percent of the land area is agricultural. The quality of water in streams and ground water are affected by both natural and anthropogenic factors. The quality of water is generally satisfactory for most domestic, public, industrial, and irrigation uses. Most water is of the calcium-magnesium-bicarbonate type. The initial six-year phase of the Upper Mississippi River Basin National Water-Quality Assessment, lasting from 1994 to 1999, focuses on data collection and analysis in a 19,500 square-mile area in Minnesota and Wisconsin that includes the Twin Cities metropolitan area. The study design focuses on factors that have an influence on or a potential influence on the water quality in that area. The most significant contaminants include nutrients, pesticides, synthetic-organic compounds, and trace metals. Environmental stratification consists of dividing the study unit into subareas with homogeneous characteristics to assess natural and anthropogenic factors affecting water quality. The assessment of water quality in streams and in aquifers is based on the sampling design that compares water quality within homogeneous subareas defined by subbasins or aquifer boundaries. The study unit is stratified at four levels for the surface-water component: glacial deposit composition, surficial geology, general land use and land cover, and secondary land use. Ground-water studies emphasize shallow ground water where quality is most likely influenced by overlying land use and land cover. Stratification for ground-water sampling is superimposed on the distribution of shallow aquifers. For each aquifer and surface-water basin this stratification forms the basis for the proposed sampling design used in the Upper Mississippi River Basin National Water-Quality Assessment.

Minnesota, Wisconsin↗

The emplacement of ophiolites by collision

Ophiolites, recognized in most of the world's orogenic belts, are generally interpreted to be oceanic crust and upper mantle (lithosphere) fragments that have been incorporated into continental margins at consuming plate boundaries. We suggest that the mechanism for ophiolite emplacement is the same in both the Alpine and Andean-type orogenes. In both geological settings, obduction of oceanic lithosphere onto the continental lithosphere is caused by the convergence of light, buoyant bodies such as oceanic plateaus, continental slivers, island arcs, or old hot spot traces. For example, the Troodos ophiolite complex, previously interpreted by some workers as resulting from continental collision, may have been emplaced by the collision of Cyprus with the Eratosthenes Plateau embedded in the oceanic eastern Mediterranean crust. On the other hand, the Upper Jurassic Coast Range Ophiolites of California, previously interpreted as resulting from typical oceanic subduction, may be the result of a continuous injection of thick nonsubductable packages of light, continentally derived sedimentary rocks, seamounts, and plateaus into the subduction zones. Many other ophiolite complexes may be similarly related to accreted terranes.

Journal of Geophysical Research↗

Maps showing distribution of copper in heavy-mineral concentrates, Richfield 1° x 2° quadrangle, Utah

These maps are part of a folio of maps of the Richfield 1° x 2 ° quadrangle, Utah, prepared under the Conterminuous United States Mineral Assessment Program. Other publications in this folio are listed in the selected references. Located in west-central Utah, the Richfield quadrangle covers the eastern part of the Plioche-Marysvale igneous and mineral belt, which extends from the vicinity of Plioche in southeastern Nevada east-northeastward for 250 km (155 mi) into central Utah. The western two-thirds of the Richfield quadrangle is in the Basin and Range province and the eastern third is in the High Plateaus of Utah, a subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of latest Precambrian and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrane into a series of north-trending fault blocks; the uplifted mountain areas were deeply eroded and the resulting debris deposited in the adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed during igneous activity in middle and late Cenozoic time. The regional sampling program was designed to define broad geochemical patterns and trends which can be utilized along with geologic and geophysical data to assess the mineral resource potential for this quadrangle. These maps of the Richfield 1° x 2° quadrangle show the regional distributions of copper in two fractions of heavy-mineral concentrates of drainage sediments.

Utah↗

Maps showing distribution of lead in heavy-mineral concentrates, Richfield 1° x 2° quadrangle, Utah

These maps are part of a folio of maps of the Richfield 1° x 2 ° quadrangle, Utah, prepared under the Conterminuous United States Mineral Assessment Program. Other publications in this folio are listed in the selected references. Located in west-central Utah, the Richfield quadrangle covers the eastern part of the Plioche-Marysvale igneous and mineral belt, which extends from the vicinity of Plioche in southeastern Nevada east-northeastward for 250 km (155 mi) into central Utah. The western two-thirds of the Richfield quadrangle is in the Basin and Range province and the eastern third is in the High Plateaus of Utah, a subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of latest Precambrian and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrane into a series of north-trending fault blocks; the uplifted mountain areas were deeply eroded and the resulting debris deposited in the adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed during igneous activity in middle and late Cenozoic time. The regional sampling program was designed to define broad geochemical patterns and trends which can be utilized along with geologic and geophysical data to assess the mineral resource potential for this quadrangle. These maps of the Richfield 1° x 2° quadrangle show the regional distributions of copper in two fractions of heavy-mineral concentrates of drainage sediments.

Utah↗

Maps showing distribution of thorium in heavy-mineral concentrates, Richfield 1° x 2° quadrangle, Utah

These maps are part of a folio of maps of the Richfield 1° x 2 ° quadrangle, Utah, prepared under the Conterminuous United States Mineral Assessment Program. Other publications in this folio are listed in the selected references. Located in west-central Utah, the Richfield quadrangle covers the eastern part of the Plioche-Marysvale igneous and mineral belt, which extends from the vicinity of Plioche in southeastern Nevada east-northeastward for 250 km (155 mi) into central Utah. The western two-thirds of the Richfield quadrangle is in the Basin and Range province and the eastern third is in the High Plateaus of Utah, a subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of latest Precambrian and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrane into a series of north-trending fault blocks; the uplifted mountain areas were deeply eroded and the resulting debris deposited in the adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed during igneous activity in middle and late Cenozoic time. The regional sampling program was designed to define broad geochemical patterns and trends which can be utilized along with geologic and geophysical data to assess the mineral resource potential for this quadrangle. These maps of the Richfield 1° x 2° quadrangle show the regional distributions of copper in two fractions of heavy-mineral concentrates of drainage sediments.

Utah↗

Maps showing distribution of tin in heavy-mineral concentrates, Richfield 1° x 2° quadrangle, Utah

These maps are part of a folio of maps of the Richfield 1° x 2 ° quadrangle, Utah, prepared under the Conterminuous United States Mineral Assessment Program. Other publications in this folio are listed in the selected references. Located in west-central Utah, the Richfield quadrangle covers the eastern part of the Plioche-Marysvale igneous and mineral belt, which extends from the vicinity of Plioche in southeastern Nevada east-northeastward for 250 km (155 mi) into central Utah. The western two-thirds of the Richfield quadrangle is in the Basin and Range province and the eastern third is in the High Plateaus of Utah, a subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of latest Precambrian and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrane into a series of north-trending fault blocks; the uplifted mountain areas were deeply eroded and the resulting debris deposited in the adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed during igneous activity in middle and late Cenozoic time. The regional sampling program was designed to define broad geochemical patterns and trends which can be utilized along with geologic and geophysical data to assess the mineral resource potential for this quadrangle. These maps of the Richfield 1° x 2° quadrangle show the regional distributions of copper in two fractions of heavy-mineral concentrates of drainage sediments.

Utah↗

Maps showing distribution of tungsten in heavy-mineral concentrates, Richfield 1° x 2° quadrangle, Utah

These maps are part of a folio of maps of the Richfield 1° x 2 ° quadrangle, Utah, prepared under the Conterminuous United States Mineral Assessment Program. Other publications in this folio are listed in the selected references. Located in west-central Utah, the Richfield quadrangle covers the eastern part of the Plioche-Marysvale igneous and mineral belt, which extends from the vicinity of Plioche in southeastern Nevada east-northeastward for 250 km (155 mi) into central Utah. The western two-thirds of the Richfield quadrangle is in the Basin and Range province and the eastern third is in the High Plateaus of Utah, a subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of latest Precambrian and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrane into a series of north-trending fault blocks; the uplifted mountain areas were deeply eroded and the resulting debris deposited in the adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed during igneous activity in middle and late Cenozoic time. The regional sampling program was designed to define broad geochemical patterns and trends which can be utilized along with geologic and geophysical data to assess the mineral resource potential for this quadrangle. These maps of the Richfield 1° x 2° quadrangle show the regional distributions of copper in two fractions of heavy-mineral concentrates of drainage sediments.

Utah↗

Maps showing distribution of zinc in heavy-mineral concentrates, Richfield 1° by 2° quadrangle, Utah

These maps are part of a folio of maps of the Richfield 1° x 2° quadrangle, Utah, prepared under the Coterminous United States Mineral Assessment Program. Other publications in this folio are listed in the selected references. Located in west-central Utah, the Richfield quadrangle covers the eastern part of the Plioche-Marysvale igneous mineral belt, which extends from the vicinity of Plioche in southeastern Nevada east-northeastward for 250 km (155 mi) into central Utah. The western two-thirds of the Richfield quadrangle is in the Basin and Range province and the eastern third is in the High Plateaus of Utah, a subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of latest Precambrian and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related instrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrane into a series of north-trending fault blocks; the uplifted mountain areas were deeply eroded and the resulting debris deposited in the adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed during igneous activity in middle and late Cenozoic time. The regional sampling program was designed to define broad geochemical patterns and trends which can be utilized along with geologic and geophysical data to assess the mineral resource potential for this quadrangle. These maps of the Richfield 1° x 2° quadrangle show the regional distributions of zinc in two fractions of heavy-mineral concentrates of drainage sediments.

Utah↗

Geologic, aeromagnetic and mineral resource potential maps of the Whisker Lake Wilderness, Florence County, Wisconsin

The Wilderness Act (Public Law 88-577, September 3, 1964) and related acts require the U.S. Geological Survey and the U.S. Bureau of Mines to survey certain areas on Federal lands to determine their mineral resource potential. Results must be made available to the public and be submitted to the President and the Congress. This report presents the results of a mineral resource survey of the Whisker Lake Wilderness in the Nicolet National Forest, Florence County, Wisconsin. The wilderness was established by Public Law 95-494, October 21, 1978. The mineral resource potential of the Whisker Lake Wilderness in the Nicolet National Forest, Florence County, northeastern Wisconsin, was evaluated in 1982. The bedrock consists of recrystallized and deformed volcanic and sedimentary rocks of Early Proterozoic age. Sand and gravel are the only identified resources in the Whisker Lake Wilderness. However, the area is somewhat isolated from current markets and both commodities are abundant regionally. The wilderness also has low potential for peat in swampy lowlands. The southwestern part of the wilderness has a low to moderate mineral resource potential for stratabound massive-sulfide (copper-zinc-lead) deposits.

Wisconsin↗