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Person

Christopher S Holm-Denoma

Research Geologist

Geology, Geophysics, and Geochemistry Science Center

Email: cholm-denoma@usgs.gov
Office Phone: 303-236-5454
Fax: 303-236-3200
ORCID: 0000-0003-3229-5440

Location
Box 25046, Denver Federal Center, Mail Stop 973
Denver , CO 80225-0046
USA

Supervisor: Albert H Hofstra
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In 2016, with National Park Service support, several previously undated plutons were sampled in Glacier Bay National Park and Preserve along the west side of Glacier Bay for age determinations. Geochronologic analyses were conducted to determine the ages of the plutonic rocks in the Glacier Bay area. Five samples were collected by Frederic Wilson (USGS Alaska Science Center), from Dundas Bay and Geikie Inlet, and dated by laser ablation-inductively coupled plasma mass spectrometry U-Pb methods. The dates obtained ranged from approximately 112-118 Ma, indicating that these samples are younger than the Saint Elias plutonic suite (ca. 160 Ma-130Ma), which runs along the same trend as the sampled rocks to the south.
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This Laser ablation ICPMS U-Pb detrital zircon data set supports mapping and stratigraphic interpretations of the Upper Devonian Ignacio Formation in southwestern Colorado (Silverton area). All samples were collected from a measured stratigraphic section called "Sultan Creek South" located at 37.710010 and -107.67530 (Evans and others, 2019). The Ignacio Formation was previously interpreted as Cambrian, but evidence that it is Devonian includes reexamined fossil data and detrital zircon U-Pb geochronology. The Ignacio Formation has a stratigraphic trend of detrital zircon ages shifting from a single ca. 1.7 Ga age peak to bimodal ca. 1.4 Ga and ca. 1.7 Ga age peaks, which represents local source-area unroofing history....
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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...
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Select samples were collected from boreholes in Arctic Alaska to determine the U-Pb ages of zircon to determine a maximum depositional age of the geologic units and/or provenance of the zircon in the samples. Samples were collected from the Department of Natural Resources-Alaska Geologic Materials Center in Anchorage Alaska and sent to U.S. Geological Survey-Geology, Geophysics and Geochemistry Science Center, Denver, CO for mineral separation and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) U-Pb geochronology analyses. The information is this report includes LA-ICPMS analyses conducted between 2016 and 2018 of at least 120 zircon grains or more (if recovered from sample) from twenty samples...
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This dataset includes U-Pb detrital zircon age data for samples from the Ingleside and Lyons formations in north-central Colorado collected from Owl Canyon and Park Creek Reservoir, from the Molas and Hermosa formations in southwestern Colorado collected from Molas Pass, and from the Lykins formation and its equivalents along the Front Range and in southeastern Colorado. It accompanies publications 'The Permian-Triassic Transition in Colorado' published in Unfolding the Geology of the West: Geological Society of America Field Guide 44, and 'Detrital zircon geochronology of Pennsylvanian-Permian strata in Colorado: evidence for Appalachian-derived sediment and implications for the timing of Ancestral Rocky Mountains...
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