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At least 973 records · Page 54Linked to original sources

Maps showing distribution of anomalies based on the use of scoresum plots for selected groupings of elements in samples of minus-60-mesh (0.25-MM) stream sediment, Walker Lake 1 degree by 2 degrees Quadrangle, California and Nevada

This report is part of a folio of maps of the Walker Lake 1 o x 2 o quadrangle, California and Nevada, prepared under the Conterminous United States Mineral Assessment Program. The folio includes geological, geochemical, and geophysical maps, as well as mineral resources assessment maps, which identify selected known or possible mineral-deposit environments in the quadrangle. The geochemical maps show the distributions of selected individual elements (Chaffee and others, 1988 a, b, c) and the distributions of selected groups of elements (Chaffee, 1988a, b, c). Discussions accompanying the individual element maps are restricted to mineral residences of the individual elements as well as to what types of mineral deposits and environments may be represented by anomalies of a particular element. Discussions accompanying the multielemental maps describe the types of mineral deposits that may be related to each element group and indicate the most favorable localities for these deposits.

California, Nevada↗

Maps showing distribution of anomalies based on the use of scoresum plots for selected groupings of elements in samples of nonmagnetic heavy-mineral concentrate, Walker Lake 1 degree by 2 degrees Quadrangle, California and Nevada

This report is part of a folio of maps of the Walker Lake 1 o x 2 o quadrangle, California and Nevada, prepared under the Conterminous United States Mineral Assessment Program. The folio includes geological, geochemical, and geophysical maps, as well as mineral resource assessment maps which identify selected known or possible mineral-deposit environments in the quadrangle. The geochemical maps show the distributioins of selected individual elements (Chaffee and others 1988a, b, c, d) and the distributions of selected groups of elements (Chaffee, 1988a, b). Discussions accompanying the individual element maps are restricted to possible mineral residences of the individual elements as well as to what types of mineral deposits and environments may be represented by anomalies of a particular element. Discussions accompanying the multielement maps describe the types of mineral deposits that may be related to each element group and indicate the most favorable localities for these deposits.

California, Nevada↗

Geophysical maps and interpretations of the Domeland Wilderness and contiguous Roadless Areas, Kern and Tulare counties, California

Geophysical maps were compiled and constructed from gravity and aeromagnetic surveys of the study area in order to assist the geologic mapping and the mineral resource assessment of the Domeland Wilderness and contiguous roadless areas. The isostatic residual gravity map (fig. 1) primarily reflects lateral density variations within the upper crust beneath the region studied. The aeromagnetic map reflects the distribution of magnetization in the underlying rocks. Because different rock types are often characterized by different densities and magnetic properties, the geophysical maps can be used to extend the geologic mapping into areas covered by surficial deposits and to help determine the subsurface locations and attitudes of contacts between rock units with contrasting properties.

California↗

Stream-sediment and panned-concentrate geochemical maps of the Buffalo Peaks Wilderness Study Area, Lake, Park, and Chaffee counties, Colorado

Under provisions of the Wilderness Act (Public Law 88-577, September 3, 1964), the U.S. Geological Survey and the U.S. Bureau of Mines have been conducting mineral surveys of areas selected for possible inclusion in the National Wilderness Preservation System. This report presents results of geochemical studies carried out in June and July, 1982, as part of the investigation of the Buffalo Peaks Wilderness Study Area, Colo. Stream-sediment and panned-concentrate samples were collected from about 80 sites on streams draining the study area. Analytical results and a sample locality map were published by Domenico and others (1984). The geologic and mineral resource potential maps of the study area were prepared by Hedlund and others (1983). The Buffalo Peaks Wilderness Study Area encompasses a major portion of the Mosquito Range, which is structurally part of the east flank of the north-northwest-trending Sawatch anticline. Bedrock in the west two-thirds of the study area is made up of Precambrian igneous and metamorphic rocks of the core of the anticline, whereas bedrock in the east one-third is mostly east dipping Paleozoic sedimentary rocks. In the vicinity of East and West Buffalo Peaks, the sequence of Paleozoic sedimentary rocks is covered by Tertiary extrusive rocks. Major faults generally run parallel to the north-northwest trend of the Arkansas River Valley, which is an expression of the Arkansas River segment of the Rio Grande depression, and the Sawatch anticline in the study area. Some faults are probably of late Precambrian age; major recurrent displacement is known to have occurred on most faults during Laramide time and in the Pliocene and Miocene. The study area is bounded by several areas of known mineralization (Hedl und and others, 1983). Vein and bedding replacement deposits of silver, zinc, and lead were mined from 1890 until about 1918 in the vicinity of Weston Pass (map A), on the northeastern border of the study area. Gold and silver were mined from about 1860 until about 1880 from veins in the Granite area (map A), on the northwestern border of the study area; minor prospecting activity continues today. From 1935 to 1937, veins of gold, silver, and base metals were mined in the vicinity of Fourmile Creek, on the southwestern border of the study area (map A). Recently, active uranium prospecting has been taking place in the vicinity of the Middle Fork of Salt Creek, on the southeastern border of the study area (map A).

Colorado↗

Seismicity map of the state of Idaho

This map is one of a series of seismicity maps produced by the U.S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This map shows only those earthquakes with epicenters located within the boundaries of Idaho, even though earthquakes in nearby states or countries may have been felt or may have caused damage in Idaho. The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1987) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that had not been previously used. The data in table 1 represent earthquake on the basis of historical and current information. Some of the aftershocks from large earthquake are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used. The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the Arabic number to the right of the triangle. A Roman numeral to the left of a triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of all earthquakes at that geographic location. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

Idaho↗

Preliminary map showing landslides in Alabama

This map brings together data from all known reports on landslides in Alabama mentioned by Alger and Brabb (1985) and information provided by State and County Highway Departments in response to a questionnaire sent in 1981 by K. F. Rheams. Additional landslide data from the northern part of the state and from Jefferson County were added by Fred Taylor and E. E. Brabb from reports by Pomeroy (1982), Thomas (1979, 1982), and Szabo and others (1979). The locations of two landslides were provided by the U.S. Forest Service (written commun., 1982), and a few more additional landslide locations were noted by K. F. Rheams in 1981 and by E. E. Brabb in 1982. Locations of landslides from the various data sources were transferred to this map by measuring the distance from known landmarks. Substantial differences in scale, differential swelling and shrinking of paper source maps, and other technical problems in transferring the landslide data may have led to errors of as much as one mile in plotting the locations. The landslide locations, therefore, are located only approximately. Many more landslides exist in Alabama but have not yet been recognized or recorded in public documents. The absence of a landslide symbol on this map, therefore, does not indicate that an area is necessarily free of landslides. Conversely, the clustering of landslide symbols in an area should not be used to indicate that the area is unsafe, but rather that many landslides have been reported and that investigation of the problem by qualified geologists and engineers is prudent before development takes place. This map should be considered preliminary in the sense that a systematic evaluation of all areas in Alabama for landslides using standard photographic interpretation techniques has not yet been done. The user of this map is referred to Pomeroy and Thomas (1935) for a discussion of slope—stability problems in northern Alabama.

Alabama↗

Seismicity map of the state of Indiana

This map is one of a series of seismicity maps produced by the U. S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This map shows only those earthquakes with epicenters located within the boundaries of Indiana, even though earthquakes in nearby states may have been felt or may have caused damage in Indiana. The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1983) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that had not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used. The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the arabic number to the right of the triangle. A Roman numeral to the left of a triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of all earthquakes at that geographic location. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

Indiana↗

Seismicity map of the state of Ohio

This map is one of a series of seismicity maps produced by the U. S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This map shows only those earthquakes with epicenters located within the boundaries of Ohio, even though earthquakes in nearby states or countries may have been felt or may have caused damage in Ohio. The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1983) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that had not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used. The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted . These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the arabic number to the right of the triangle. A Roman numeral to the left of a triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of all earthquakes at that geographic location. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

Ohio↗

Seismicity map of the state of Vermont

This map is one of a series of seismicity maps produced by the U. S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This map shows only those earthquakes with epicenters located within the boundaries of Vermont, even though earthquakes in nearby states or countries may have been felt or may have caused damage in Vermont. The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1983) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that had not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used. The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the arabic number to the right of the triangle. A Roman numeral to the 1eft of a triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of all earthquakes at that geographic location. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

Vermont↗

Seismicity map of the state of North Carolina

This map is one of a series of seismicity maps produced by the U. S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This map shows only those earthquakes with epicenters located within the boundaries of North Carolina, even though earthquakes in nearby states may have been felt or may have caused damage in North Carolina. The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1983) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that had not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used. The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the arabic number to the right of the triangle. A Roman numeral to the left of a triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of a11 earthquakes at that geographic location. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

North Carolina↗

Summary and interpretation of geochemical maps for stream sediment and heavy mineral concentrate samples, Mount Hayes Quadrangle, eastern Alaska Range, Alaska

This report and accompanying maps summarize the results of geochemical exploration studies in the Mount Hayes quadrangle, Alaska. This is one of a series of maps and reports on the geological, geochemical, and geophysical studies of the quadrangle prepared as part of the Alaskan Mineral Resource Assessment Program (AMRAP) of the U.S. Geological Survey. These maps are part of the Mount Hayes l:250,000-scale folio. The geochemical studies were made in order to identify and define mineralized areas in the quadrangle and to aid in characterizing the nature of the mineral occurrences within these areas. The studies included the collection of composite samples of stream sediment or glacial debris and preparation of these samples, as described by O'Leary and others (1982), to yield a minus-80-mesh (0.2-mm) fraction and nonmagnetic heavy-mineral-concentrate fraction consisting of mineral grains having a specific gravity greater than 2.85. Samples were collected at 911 sites either from tributary streams or tributary glaciers with drainage basins ranging from 1 to 5 sq mi in area. The samples were analyzed for 30 elements by semiquantitative emission spectrography (O'Leary and others, 1982). The stream-sediment and glacial-debris samples also were analyzed for zinc by an atomic absorption method (Ward and others, 1969), and those results were used in preparing map A. The maps in this report show drainage basins in which the stream sediment or glacial debris contained anomalously high amounts of selected metals. The geologic base map aids in showing the geologic terranes of the quadrangle. The accompanying tables give frequencies and cumulative percents of the selected metals for all major geologic terranes within the quadrangle.

Alaska↗

Aeromagnetic maps of the Uinta and Piceance Basins and vicinity, Utah and Colorado

In order to understand the evolution of sedimentary basins, it is important to understand their tectonic setting. In a U.S. Geological Survey (USGS) study of the Uinta and Piceance basins in Utah and Colorado, this understanding is approached through characterization of subsurface structure and lithology of a large region encompassing the basins. An important tool for interpreting these subsurface features is aeromagnetic data. Aeromagnetic anomalies represent variations in the strength and direction of the Earth's magnetic field that are produced by rocks containing a significant number of magnetic minerals (commonly magnetite). The shape and magnitude of an anomaly produced by one body of rock are complexly related to the amount of magnetic minerals present, the magnetic properties of those minerals (determined by a number of factors, including the history of the rock), and the shape of the rock body. In the study area, only crystalline basement rocks and volcanic rocks are likely to contain enough magnetic minerals to produce anomalies; sedimentary rocks and metasediments are generally so poor in magnetic minerals that their magnetic effects cannot be detected by the types of surveys presented in this report. Patterns of anomalies on aeromagnetic maps can reveal not only lithologic differences related to magnetite content, but structural features as well, such as faults that have juxtaposed crystalline rocks against sedimentary rocks, and upwarps of crystalline basement underlying sedimentary sequences. Tectonic features of regional extent may not become apparent until a number of aeromagnetic surveys have been compiled and plotted at the same scale. Commonly the compilation involves piecing together data from surveys that were flown at different times and have widely disparate flight specifications and data reduction procedures. The data may be compiled into a composite map, where all the pieces are plotted onto one map without regard to the differences in flight elevation and datum, or they may be compiled into a merged map, where all survey data are analytically reduced to a common flight elevation and datum, and then digitally merged at the survey boundaries. The composite map retains the original resolution of all survey data, but computer methods to enhance or model regional features crossing the survey boundaries cannot be applied. On the other hand, these computer methods can be applied to the merged data, but the resolution of the data may be somewhat diminished. This report presents both composite and merged aeromagnetic maps for a large region that includes the Uinta Basin in Utah and the Piceance basin in Colorado (fig. 1).

Colorado;Utah↗

Aeromagnetic maps of the Colorado River region including the Kingman, Needles, Salton Sea, and El Centro 1 degree by 2 degrees quadrangles, California, Arizona, and Nevada

Aeromagnetic data for the Colorado river region have been compiled as part of the Pacific to Arizona Crustal Experiment (PACE) Project. The data are presented here in a series of six compilations for the Kingman, Needles, Salton Sea, and El Centro 1 degree by 2 degree quadrangles, California, Arizona, and Nevada, at scales of 1:250,000 and 1:750,000. The scales and map areas are identical to those used by Mariano and others (1986) to display the Bouguer and isotatic residual gravity for this region. Data were compiled separately for the Kingman quadrangle, the Needles quadrangle, and an area covering the Salton Sea quadrangle and part of the El Centro quadrangle. Aeromagnetic anomalies are produced by variations in the strength and direction of the magnetic field of rocks that include magnetic minerals, commonly magnetite. Patterns of anomalies on aeromagnetic maps can reveal structures - for example, faults which have juxtaposed magnetic rocks against non-magnetic rocks, or areas of alteration where magnetic minerals have been destroyed by hydrothermal activity. Tectonic features of regional extent may not become apparent until a number of aeromagnetic surveys have been compiled and plotted at the same scale. Commonly the compilation involves piecing together data from surveys that were flown at different times with widely disparate flight specifications and data reduction procedures. The data may be compiled into a composite map, where all the pieces are plotted onto one map without regard to the difference in flight elevation and datum, or they may be compiled into a merged map, where all survey data are analytically reduced to a common flight elevation and datum, and then digitally merged at the survey boundaries. The composite map retains the original resolution of all the survey data, but computer methods to enhance regional features crossing the survey boundaries may not be applied. On the other hand, computer methods can be applied to the merged data, but the accuracy of the data may be slightly diminished.

Arizona, California, Nevada↗

Geophysically inferred structural and lithologic map of the precambrian basement in the Joplin 1° x 2° quadrangle, Kansas and Missouri

This report is an analysis of regional gravity and aeromagnetic data that was carried out as part of a Conterminuous United States Mineral Assessment Program (CUSMAP) study of the Joplin 1° X 2° quadrangle, Kansas and Missouri. It is one in a series of reports representing a cooperative effort between the U.S. Geological Survey, Kansas Geological Survey, and Missouri Department of Natural Resources, Division of Geology and Land Survey. The work presented here is part of a larger project whose goal is to assess the mineral resource potential of the Paleozoic sedimentary section and crystalline basement within the quadrangle. Reports discussing geochemical, geological, and various other aspects of the study area are included in this Miscellaneous Field Studies Map series as MF-2125-A through MF-2125-E. Geophysical interpretation of Precambrian crystalline basement lithology and structure is the focus of this report. The study of the crystalline basement is complicated by the lack of exposures due to the presence of a thick sequence of Phanerozoic sedimentary cover. In areas where there are no outcrops, the geologist must turn to other indirect methods to assist in an understanding of the basement. Previous investigations of the buried basement in this region used available drill hole data, isotope age information, and regional geophysical data (Sims, 1990; Denison and others, 1984; Bickford and others, 1986). These studies were regional in scope and were presented at state and multistate scales. The work documented here used recently collected detailed gravity and aeromagnetic data to enhance the regional geologic knowledge of the area. Terrace-density and terrace-magnetization maps were calculated from the gravity and aeromagnetic data, leading directly to inferred physical-property (density and magnetization) maps. Once these maps were produced, the known geology and drill-hole data were reconciled with the physical-property maps to form a refined structural and lithologic map of the crystalline basement.

Kansas, Missouri↗

Geologic map of the Saint Joseph area, Missouri and Kansas

This map was prepared as a collaborative effort with the Missouri Division of Geology and Land Survey, the Kansas Geological Survey, and the Nebraska Conservation and Survey Division. Map units and preliminary contacts between units were identified using stereoscopic pairs of high altitude, false color infrared, aerial photographs. Contacts were drawn on twelve USGS 7.5-minute topographic maps, and were checked in the field. U.S. Department of Agriculture Soil Survey maps at a scale of 1:62,500 for Buchanan County, Andrew County, Platte County, and Doniphan County were used to provide a general overview of the soils of the area. A U.S. Geological Survey map at a scale of 1:24,000 showing the geohydrology of Doniphan County, Kansas; soil surveys at a scale of 1:24,000 for Buchanan County, Andrew County, and Platte County; and soil survey at a scale of 1:20,000 for Doniphan were used to corroborate map contacts and field observations.

Kansas, Missouri↗

Generalized surficial geologic map of the Pueblo 1° x 2° quadrangle, Colorado

Fifty-three types of surficial geologic deposits and residual materials of Quaternary age are described in a pamphlet and located on a map of the greater Pueblo area, in part of the Front Range, in the Wet and Sangre de Cristo Mountains, and on the plains east of Colorado Springs and Pueblo. Deposits formed by landslides, wind, and glaciers, as well as colluvium, residuum, alluvium, and others are described in terms of predominant grain size, mineral or rock composition (e.g., gypsiferous, calcareous, granitic, andesitic), thickness, and other physical characteristics. Origins and ages of the deposits and geologic hazards related to them are noted. Many lines drawn between units on our map were placed by generalizing contacts on published maps. However, in 1997-1999 we mapped new boundaries as well. The map was projected to the UTM projection. This large map area extends from near Salida (on the west edge), eastward about 107 mi (172 km), and from Antero Reservoir and Woodland Park on the north edge to near Colorado City at the south edge (68 mi; 109 km).

Colorado↗

Geologic map of the Lower Hurricane Wash and vicinity, Mohave County, Northwestern Arizona

This digital map database is compiled from published open file reports, and new mapping by the author, and represents the general distribution of surficial and bedrock geology in the mapped area. The map area lies within the Shivwits and Uinkaret Plateaus, subplateaus of the southwestern part of the Colorado Plateau hypsographic province. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database delineates map units that are identified by age and lithology, following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Miscellaneous Field Studies Map↗

Map showing ground water conditions in the Fairbanks D-2 SE Quadrangle, Alaska

The primary controlling factors determining ground-water conditions in the Fairbanks D-2 SE quadrangle are (1) topographic position, (2) water-bearing characteristics of the rocks, and (3) distribution of permafrost. These interrelated factors generally limit the conditions in any particular area. Basic data from the geologic map of the Fairbanks D-2 SE quadrangle (Map I-942, Pewe and others, in press), the map showing distribution of permafrost in the Fairbanks D-2 SE quadrangle (Map MF-669A, Pewe and Bell, 1975a), and the map showing foundation conditions in the Fairbanks D-2 SE quadrangle (Map MF 669D, Pewe and Bell, 1975c) have been used in conjunction with well data to establish generalized potential ground-water conditions.

Alaska↗