Filters: partyWithName: Joseph P Colgan (X) > Categories: Data (X)
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This dataset is the assembled analytical results of geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during geologic mapping in and around those districts, whereas much of that for samples from the Goldfield district were obtained by Ashley (1974; 1979; 1990). Additional data were derived from samples collected between 2012–2017, as part of the U.S. Geological Survey Mineral Resources Program funded project titled: “Magmatic-tectonic history...
Categories: Data;
Tags: Ar,
Divide mining district,
Economic Geology,
Esmeralda County,
Fraction Tuff,
This digital data release contains geospatial data for the geologic map of the O’Neill 1 degree by 2 degree geologic map in Nebraska, originally published in 2008 by R.E. Diffendal and others. The original map consists of a 1:250,000 scale map plate with a “stack unit” structure showing multiple overlying units, as well as several roughly 1:750,000 scale maps in an accompanying pamphlet showing bedrock geology and structure contours. To capture as much of this content as possible in a geodatabase, three “layers” are included in this database: 1) Overlay polygons showing Quaternary loess deposits (Qes) where they overlay older Quaternary units; 2) a layer (consisting of line and polygon feature classes) showing Quaternary...
This dataset contains apatite and zircon U-Th(He)data, 4He/3He thermochronologic data, and apatite fission-track data from the southern Stillwater Range, Nevada
This dataset contains argon-argon and U-Pb geochronologic data collected from igneous rocks in the Stillwater Range, Clan Alpine, and Desatoya Mountains, western Nevada, USA First posted - November 16, 2017 Revised - February 26, 2019 (version 2.0) Revised - December 12, 2023 (version 3.0)
Categories: Data,
Data Release - Revised;
Tags: Clan Alpine Mountains,
Desatoya Mountains,
Geochemistry,
Geochronology,
Stillwater Range,
The Cortez region in north-central Nevada hosts the second largest concentration of Carlin-type gold deposits in Nevada. The origin of these deposits is debated, and major questions remain concerning the role of magmatism in their formation. To understand the Mesozoic and Cenozoic magmatic history of the Cortez region, twenty-one samples of igneous rocks ranging from Jurassic to Eocene were sampled, including drill core from around several of the major deposits. Individual zircon grains from these samples were analyzed by Sensitive High Resolution Ion Microprobe (SHRIMP) for uranium lead ages and a suite of trace elements. Most samples are Eocene, in particular the dikes associated with Cortez mineralization. Although...
This data release presents geologic map data for the bedrock geology of the Durango 1-degree by 2-degree quadrangle. Geologic mapping incorporates new interpretive contributions and compilation from published geologic map data sources primarily ranging from 1:24,000 to 1:50,000 scale. Much of the geology incorporated from published geologic maps is adjusted based on digital elevation model and natural-color image data sources to improve spatial resolution of the data. Spatial adjustments and new interpretations also eliminate mismatches at source map boundaries. This data set represents only the bedrock geology; deposits of unconsolidated, surficial materials that are typically, but not exclusively, Quaternary in...
U-Pb ages and concentrations of selected trace elements were analyzed in zircon crystals from nine samples of Cenozoic igneous rocks collected near Tonopah, Nevada. U-Pb ages were obtained from four samples, and trace element analyses were obtained from both the dated samples and an additional five samples.
The magmatic, tectonic, and topographic evolution of what is now the northern Great Basin remains controversial, notably the temporal and spatial relation between magmatism and extensional faulting. This controversy is exemplified in the northern Toiyabe Range of central Nevada, where previous geologic mapping suggested the presence of a caldera that sourced the late Eocene (34.0 mega-annum [Ma]) tuff of Hall Creek. This region was also inferred to be the locus of large-magnitude middle Tertiary extension (more than 100 percent strain) localized along the Bernd Canyon detachment fault, and to be the approximate location of a middle Tertiary paleodivide that separated east and west-draining paleovalleys. Geologic...
Categories: Data;
Tags: Lander County,
Major Element Analysis,
Nevada,
Toiyabe Range,
Trace Element Analysis
This digital data release contains geospatial data for the 1:250,000 scale geologic map of the Grand Island 1 degree by 2 degree quadrangle, Nebraska, originally published by Dreeszen and others (1973). The database includes line and polygon features depicting the extent of the Miocene Ogallala Formation and underlying Cretaceous rocks. The original map also included shaded patches indicating outcrop areas, and contour lines depicting the thickness of Quaternary deposits; these are not included in this database. The spatial data are accompanied by non-spatial tables that describe the sources of geologic information, a description of geologic map units, a glossary of terms, and a Data Dictionary that duplicates the...
The magmatic, tectonic, and topographic evolution of what is now the northern Great Basin remains controversial, notably the temporal and spatial relation between magmatism and extensional faulting. This controversy is exemplified in the northern Toiyabe Range of central Nevada, where previous geologic mapping suggested the presence of a caldera that sourced the late Eocene (34.0 mega-annum [Ma]) tuff of Hall Creek. This region was also inferred to be the locus of large-magnitude middle Tertiary extension (more than 100 percent strain) localized along the Bernd Canyon detachment fault, and to be the approximate location of a middle Tertiary paleodivide that separated east and west-draining paleovalleys. Geologic...
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