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Person

Joseph P Colgan

Research Geologist

Geosciences and Environmental Change Science Center

Email: jcolgan@usgs.gov
Office Phone: 303-236-1021
Fax: 303-236-5601
ORCID: 0000-0001-6671-1436

Location
DFC Bldg 25
Box 25046
Denver Federal Center
Denver , CO 80225-0046
US

Supervisor: Harland Goldstein
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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, All tags...
Answering fundamental Earth Science questions requires an understanding of the absolute ages of key geologic events and the rates of geologic processes. This is accomplished by dating geologic materials, a scientific discipline known as geochronology. Currently, the geochronological data that has been generated by the USGS resides in a database that has not been updated in over 20 years, yet a significant amount of geochronology has been generated in the intervening years and continues to be generated by USGS labs. This project will develop an updated database so that all USGS age data will be accessible to key stakeholders, scientists, and the public. The project will also produce a sustainable workflow to ensure...
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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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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...
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