This dataset contains 99 electron microprobe analyses of cassiterite, chalcopyrite, galena, pyrite, sphalerite, and tetrahedrite from seven Sheep Creek drill core samples and one outcrop; and a table that describes the textures, mineralogy, and rock type of 15 thin sections of Sheep Creek drill core and observations from our study and from drill core logging by industry. These data were used to compare this prospect with others in the Bonnifield district. The dataset also contains tables of sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon dates, zircon characteristics (crystal shape, external morphology, internal features, color, aspect ratio, and cathodoluminescence zoning), and 139 U-Th-Pb analyses of the zircons from 11 metaigneous rocks collected during 1997-2005 fieldwork in the Bonnifield mining district, Alaska Range. Our zircon geochronology indicates that volcanogenic massive sulfide deposits in the Bonnifield district are hosted in felsic metavolcanic rocks that yield ages based on weighted averages of 206 Pb/238U ages (± 2-sigma errors) of 362 ± 2 Ma. These rocks overlie the stratigraphic sequence at the Sheep Creek prospect, where metaigneous rocks give ages of 372 ± 4 Ma to 366 ± 4 Ma.

This data set contains 99 electron microprobe analyses of cassiterite, chalcopyrite, galena, pyrite, sphalerite, and tetrahedrite from seven Sheep Creek drill core samples and one outcrop; and a table that describes the textures, mineralogy, and rock type of 15 thin sections of Sheep Creek drill core and observations from our study and from drill core logging by industry. These data were used to compare this prospect with others in the Bonnifield district. The data set also contains tables of sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon dates, zircon characteristics (crystal shape, external morphology, internal features, color, aspect ratio, and cathodoluminescence zoning), and 139 U-Th-Pb analyses of the zircons from 11 metaigneous rocks collected during 1997-2005 fieldwork in the Bonnifield mining district, Alaska Range. Our zircon geochronology indicates that volcanogenic massive sulfide deposits in the Bonnifield district are hosted in felsic metavolcanic rocks that yield ages based on weighted averages of 206 Pb/238U ages (± 2-sigma errors) of 362 ± 2 Ma. These rocks overlie the stratigraphic sequence at the Sheep Creek prospect, where metaigneous rocks give ages of 372 ± 4 Ma to 366 ± 4 Ma.

From 2017-2019, framework metallogenic studies were completed in the eastern Yukon-Tanana upland in eastern Alaska. Numerous previously undated plutons known or suspected to contain components of porphyry, epithermal, and intrusion-related gold systems and associated deposit types were sampled for age and zircon trace element determinations between the Black Mountain area and the Yukon border, north of the Tanana River and south of the Yukon River. A collection of 54 samples were collected by Douglas Kreiner (USGS, Alaska Science Center). Zircon grains were separated from each sample. The samples were examined by U-Pb analysis by laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) in a USGS laboratory in Denver, CO. The samples contain evidence of several discrete periods of magmatic activity, with concordant zircon dates that range from ca. 53.3-2727 Ma. The bulk of analyzed samples are between ca. 68-72 Ma. Other specific periods of magmatism based on zircon dates range from ca. 55 Ma, ca. 100-112 Ma, ca. 130 Ma, and ca. 180-211 Ma. The ca. 340-365 Ma dates are likely inherited from host rocks that were previously unidentified in the field area but are known in the regional framework geology. Archean and Proterozoic zircon dates are not common, but likely represent inheritance from sedimentary and metasedimentary protoliths from the region.

From 2017-2019, framework metallogenic studies were completed in the eastern Yukon-Tanana upland in eastern Alaska. Numerous previously undated plutons known or suspected to contain components of porphyry, epithermal, and intrusion-related gold systems and associated deposit types were sampled for age and zircon trace element determinations between the Black Mountain area and the Yukon border, north of the Tanana River and south of the Yukon River. A collection of 54 samples were collected by Douglas Kreiner (USGS, Alaska Science Center). Zircon grains were separated from each sample. The samples were examined by U-Pb analysis by laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) in a USGS laboratory in Denver, CO. The samples contain evidence of several discrete periods of magmatic activity, with concordant zircon dates that range from ca. 53.3-2727 Ma. The bulk of analyzed samples are between ca. 68-72 Ma. Other specific periods of magmatism based on zircon dates range from ca. 55 Ma, ca. 100-112 Ma, ca. 130 Ma, and ca. 180-211 Ma. The ca. 340-365 Ma dates are likely inherited from host rocks that were previously unidentified in the field area but are known in the regional framework geology. Archean and Proterozoic zircon dates are not common, but likely represent inheritance from sedimentary and metasedimentary protoliths from the region.

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. Specifically, the upper plate of a Proterozoic thrust system (ca. 1.7 Ga Twilight Gneiss) was eroded prior to exposure of the lower plate (ca. 1.4 Ga Uncompahgre Formation). These results are a significant alternative interpretation of the geologic history of the southern Rocky Mountains.

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. Specifically, the upper plate of a Proterozoic thrust system (ca. 1.7 Ga Twilight Gneiss) was eroded prior to exposure of the lower plate (ca. 1.4 Ga Uncompahgre Formation). These results are a significant alternative interpretation of the geologic history of the southern Rocky Mountains.

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 uplift' published in The Mountain Geologist.

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 uplift' published in The Mountain Geologist.

This dataset contains U-Pb isotopic data and associated dates for sampled igneous, meta-igneous, and metamorphic rocks of interior and southwestern Alaska. Samples were collected during geologic mapping and mineral deposit research from 2019 to 2023. Mapping and research were funded by the Mineral Resources Program of the U.S. Geological Survey. Mineral separations were conducted at the U.S. Geological Survey mineral separation laboratory in Denver, Colorado and GeoSep Services in Moscow, Idaho. Laser-ablation-inductively-coupled-plasma-mass spectrometry analyses of zircon grains were performed from 2020 through 2024 at the U.S Geological Survey Microbeam Laboratory in Denver, Colorado and at the GeoAnalytical Laboratory, Washington State University, Pullman, Washington by GeoSep Services.

This data release contains two datasets. One dataset is of U-Pb isotopic data and associated ages of detrital zircon grains from 16 sedimentary and metasedimentary rocks from the western Alaska Range, Livengood area and Seward Peninsula, Alaska. Two samples were collected from the York Mountains area of the Seward Peninsula of western Alaska. Three samples were collected from the Livengood quadrangle of central Alaska. Eleven samples were collected from the western Alaska Range of south-central Alaska. Detrital zircon grains from each of the sixteen samples were separated and analyzed by Apatite to Zircon, Inc. (A2Z) and Geosep Services (GSS) laboratories between 2011 and 2014, using laser-ablation-inductively-coupled-plasma-mass spectrometry (LA-ICP-MS) techniques. The second dataset contains fossil identifications and age assignments from a select sedimentary rock from the western Alaska Range of south-central Alaska. Fossils were identified by visual inspection. All samples were collected as part of geological mapping research conducted between 1984 and 2014 and funded by the Mineral Resources Program of the U.S. Geological Survey.