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At least 1,603 records · Page 89Linked to original sources
USGS2022

Preliminary bedrock geologic map of the Blythe 30' x 60' quadrangle, California and Arizona

The Blythe 30' x 60' quadrangle in southeastern California and southwestern Arizona displays complex geology that includes Mesozoic contractional deformation, metamorphism, and magmatism in addition to Cenozoic extensional deformation and magmatism. Previous geologic map compilations predate recent geologic mapping efforts that have contributed new insights into the stratigraphy and structure of this quadrangle. This new map, compiled in collaboration with the Arizona Geological Survey, incorporates these recent mapping efforts to provide an updated depiction of the quadrangle’s geologic framework. The scope of this map is limited to bedrock units of Miocene and older age because younger deposits have not been mapped in enough detail across the quadrangle to support a systematic compilation.

Arizona, California↗
USGS2012

Preliminary geologic map of the Stanardsville 7.5' quadrangle, Greene and Madison Counties, Virginia

The Stanardsville 7.5-minute quadrangle is located about 30 kilometers north of Charlottesville, Virginia, in the eastern foothills of the Blue Ridge and within the Blue Ridge physiographic province. The quadrangle contains a small part of the eastern margin of Shenandoah National Park along Saddleback Mountain just north of Swift Run Gap and stretches of Swift Run and the South, Conway, and Rapidan Rivers. The broad valleys occupied by these southeast-draining streams alternate with ridges as much as 1,700 feet high to produce a varied topography, with the 3,000- to 4,000-foot-high Blue Ridge defining the western horizon. The bedrock geology of the quadrangle was mapped at a scale of 1:24,000 as part of the Geology of Shenandoah National Park Project (which was conducted from 1995 to 2008) of the U.S. Geological Survey National Cooperative Geologic Mapping Program. The results of the mapping were incorporated in the Geologic Map of the Shenandoah National Park Region, Virginia ( USGS Open-File Report 2009-1153 ).

Virginia↗
USGS1972

Reconnaissance geology of the Sabkhat Muraysis quadrangle, Kingdom of Saudi Arabia

The Sabkhat Muraysis quadrangle .covers an area of 2843 sq km in the central part of the Kingdom of Saudi Arabia. In the northwestern quarter of the area Precambrian rocks are exposed. They are overlain toward the .south and east by sedimentary formations of Permian and younger age. Four main units of Precambrian .rocks were identified in this area. From oldest to youngest they are: hornblende-biotite granite gneiss; amphibolite and rhyolite of the Halaban Group; graywacke and chlorite-sericite schist of the Bi'r Khountina Group; and biotite-hornblende granite, The hornblende-biotite granite gneiss unit and the biotite-hornblende granite .unit are both poorly exposed and largely covered by veneers of sand, Owing to these factors the boundaries between the granitic, rocks are obscure, Much of what is shown as hornblende-biotite granite gneiss may actually be biotite-hornblende granite. The Halaban Group is represented by an older amphibolite unit called the Umm Mushraha Formation and by a younger rhyolite unit., called the Wadi al Jifr Formation. Layered and msslve components in the Umm Mushraha Formation represent metamorphosed .andesite and graywacke, ,and metamorphosed diorite., gabbro, and pyroxenite. The Wadi al Jifr Formation consists of virtually unmetamorphosed to strongly sheared and metamorphosed rhyolite, rhyolite porphyry, and rhyolite tuff which at many places has been metamorphosed to quartz-sericite schist and biotite-muscovite schist. These schists retain porphyroclasts of blue quartz which also form conspicuous phenocrysts in the unsheared rhyolite. Locally, the sheared rhyolite ha s been hydrothermally altered resulting in the formation of quartz-chlorite-ankerite veins and a sparse impregnation of pyrite. The Bi'r Khountina Group consists of a unit of graywacke and argillite with interbedded andesite that is metamorphosed to chlorite-sericite schist near the contacts of intrusive biottte-hornblende granite. This .unit is-called the Abu Sawarir Formation. It is Intruded by masslve gabbro and pyroxenite. No ancient mines or old prospects were found in the Precambrian part of the quadrangle. Three alteration zones in rhyolite near the northwestern corner of the quadrangle tend to have threshold amounts of molybdenum and tungsten, but they have only background amounts of the base metals and silver. Pyrite is more common in the altered rhyolite than in adjacent rocks. Geological mapping plus and electromagnetic surveys of this area are recommended to explore for sulfide minerals.

Open-File Report↗
USGS1995

The Alaska Mineral Resource Assessment Program: Background information to accompany geologic and mineral-resource maps of the Killik River 1°x3° quadrangle, northern Alaska

This report summarizes results of integrated geological, geochemical, and geophysical field and laboratory studies conducted by the U.S. Geological Survey in the Killik River 1°x3° quadrangle, Brooks Range, northern Alaska. These studies were designed to provide an assessment of the mineral resources of the quadrangle. The geological and geochemical data were the primary sources of information used to assess the mineral-resource potential of the quadrangle. The presence of permissive host rocks and favorable geochemical signatures in stream- and lake-sediment and (or) heavy-mineral-concentrate samples were used to infer the potential for undiscovered resources of minerals in deposits of different types. The Killik River quadrangle may contain undiscovered resources of preciousand base-metals (principally lead, silver, and zinc) in veins and breccias hosted by Devonian and Mississippian clastic sedimentary rocks or in stratiform massive sulfide deposits hosted primarily by Mississippian and Pennsylvanian sedimentary rocks. Resources of barium, phosphate, and manganese may be present in Mississippian to Jurassic sedimentary rocks. Cretaceous fluvial sedimentary rocks in the northern part of the quadrangle are permissive hosts for uranium deposits, as well as for placer deposits of heavy minerals such as gold and chromite; however, geochemical data suggest that the potential for deposits of this type is low. Numerous coal beds are present in the Cretaceous rocks throughout the northern part of the quadrangle, but the limited thickness and lateral extent of most of the beds reduce their resource potential. Although the southern third of the quadrangle has no potential for petroleum resources, there is potential in the northern two-thirds.

Alaska↗
USGS2013

Hyperspectral surface materials map of quadrangle 3468, Chak-e Wardak-Siyahgird (509) and Kabul (510) quadrangles, Afghanistan, showing iron-bearing minerals and other materials

This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Goethite and jarosite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

Open-File Report↗
USGS2013

Hyperspectral surface materials map of quadrangles 3664 and 3764, Char Shengo (123), Shibirghan (124), Jalajin (117), and Kham-Ab (118) quadrangles, Afghanistan, showing iron-bearing minerals and other materials

This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Goethite and jarosite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

Open-File Report↗
USGS2013

Hyperspectral surface materials map of quadrangle 3166, Jaldak (701) and Maruf-Nawa (702) quadrangles, Afghanistan, showing iron-bearing minerals and other materials

This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Goethite and jarosite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

Open-File Report↗
USGS2013

Hyperspectral surface materials map of quadrangle 3162, Chakhansur (603) and Kotalak (604) quadrangles, Afghanistan, showing iron-bearing minerals and other materials

This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Goethite and jarosite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

Open-File Report↗
USGS2013

Hyperspectral surface materials map of quadrangle 3266, Uruzgan (519) and Moqur (520) quadrangles, Afghanistan, showing iron-bearing minerals and other materials

This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Goethite and jarosite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

Open-File Report↗
USGS2013

Hyperspectral surface materials map of quadrangle 3164, Lashkar Gah (605) and Kandahar (606) quadrangles, Afghanistan, showing iron-bearing minerals and other materials

This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Goethite and jarosite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

Open-File Report↗
USGS2013

Hyperspectral Surface Materials Map of Quadrangle 3268, Khayr Kot (521) and Urgun (522) Quadrangles, Afghanistan, Showing Iron-bearing Minerals and Other Materials

This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Goethite and jarosite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

Open-File Report↗