Between the Cretaceous granitic rocks (Hake Batholith on the west; Cassiar Batholith to the east) are three belts of metamorphic rocks, collectively part of Yukon-Tanana terrane. These are remnants of oceanic and continental volcanic arcs, and marginal basin sediments of Early to mid-Paleozoic age. At the head of Borden Creek are thick carbonate and andesitic volcanic rocks correlated with Klinkit Group. The Ram Creek fault and Hidden Lake fault are not exposed but deduced to be steeply dipping brittle structures with northeastward thrust or transpressional offset, based upon more complete exposure to the southeast in 105B/3 map area. The former is likely of Cretaceous age; the latter was active between mid-Permian and Early Jurassic time.

This data release contains three tables of U-Pb zircon isotopic data generated from analyses of 40 metaplutonic and metavolcanic rocks from the Yukon-Tanana Upland of western Yukon and east-central Alaska and one sample from southern Yukon. One of the tables also reports U-Pb data for two titanite analyses for one of the samples. U-Pb zircon ages from analyzed samples range from 363.5 ± 3.8 to 253.1 ± 0.7 Ma and were collected from parautochthonous North America and the allochthonous Yukon-Tanana terrane. U-Pb zircon data include 216 individual analyses by ID-TIMS and 35 individual analyses of two samples by LA-ICP-MS. ID-TIMS analyses of titanite give concordant 206Pb-238U ages of 333 and 338 Ma. Two U-Pb tables report the isotopic composition of uranium (U) and thorium (Pb) measured in each grain, ratios of isotopes of lead and uranium isotopes, and the age of each grain. A third table reports interpreted U-Pb ages, sample locations, tectonic assemblage or unit, lithology, analysis method, laboratory used, and basis for age assignment. The data release also contains two tables of whole-rock major- and trace-element geochemical data for metaigneous rocks from the Yukon-Tanana Upland in east-central Alaska for augen gneiss (15 samples) and amphibolite (30 samples).

This data release contains three tables of U-Pb zircon isotopic data generated from analyses of 40 metaplutonic and metavolcanic rocks from the Yukon-Tanana Upland of western Yukon and east-central Alaska and one sample from southern Yukon. One of the tables also reports U-Pb data for two titanite analyses for one of the samples. U-Pb zircon ages from analyzed samples range from 363.5 ± 3.8 to 253.1 ± 0.7 Ma and were collected from parautochthonous North America and the allochthonous Yukon-Tanana terrane. U-Pb zircon data include 216 individual analyses by ID-TIMS and 35 individual analyses of two samples by LA-ICP-MS. ID-TIMS analyses of titanite give concordant 206Pb-238U ages of 333 and 338 Ma. Two U-Pb tables report the isotopic composition of uranium (U) and thorium (Pb) measured in each grain, ratios of isotopes of lead and uranium isotopes, and the age of each grain. A third table reports interpreted U-Pb ages, sample locations, tectonic assemblage or unit, lithology, analysis method, laboratory used, and basis for age assignment. The data release also contains two tables of whole-rock major- and trace-element geochemical data for metaigneous rocks from the Yukon-Tanana Upland in east-central Alaska for augen gneiss (15 samples) and amphibolite (30 samples).

This data release contains three tables of U-Pb zircon isotopic data generated from analyses of 40 metaplutonic and metavolcanic rocks from the Yukon-Tanana Upland of western Yukon and east-central Alaska and one sample from southern Yukon. One of the tables also reports U-Pb data for two titanite analyses for one of the samples. U-Pb zircon ages from analyzed samples range from 363.5 ± 3.8 to 253.1 ± 0.7 Ma and were collected from parautochthonous North America and the allochthonous Yukon-Tanana terrane. U-Pb zircon data include 216 individual analyses by ID-TIMS and 35 individual analyses of two samples by LA-ICP-MS. ID-TIMS analyses of titanite give concordant 206Pb-238U ages of 333 and 338 Ma. Two U-Pb tables report the isotopic composition of uranium (U) and thorium (Pb) measured in each grain, ratios of isotopes of lead and uranium isotopes, and the age of each grain. A third table reports interpreted U-Pb ages, sample locations, tectonic assemblage or unit, lithology, analysis method, laboratory used, and basis for age assignment. The data release also contains two tables of whole-rock major- and trace-element geochemical data for metaigneous rocks from the Yukon-Tanana Upland in east-central Alaska for augen gneiss (15 samples) and amphibolite (30 samples).

This report presents the geochronology results for one sample from a Late Triassic Pyroxene Mountain pluton collected in the Mount Nansen area and analyzed for U-Pb zircon dating at Boise State University. These data complement the large dataset released in the Atlas of Sack et al. (2020).

The geochronology and geochemistry of Cretaceous intrusions and associated mineralization in southeastern Yukon and southwestern NWT is the focus of a new research project. The objective is to investigate the southeastern extension of well-established plutonic suites currently recognized in central and western Yukon. Here we report five new U-Pb zircon ges from the study area that indicate that at least three distinct ages of intrusions are present. Two bodies (Bennett Creek pluton and an unnamed body west of Tungsten) give ages of ~91 Ma and are correlated with the Tombstone Plutonic Suite. Two phases of the Coal River batholith give ages of ~96 Ma and are considered to be part of the Tay River plutonic suite. Finally, the Mt. Billings Batholith east of Tuchitua Junction gives an age of ~106 Ma, and is correlated with the Anvil plutonic suite. Compositionally, the intrusions range from monzogranite to granodiorite and most contain at least minor amounts of biotite ± hornblende ± magnetite. Also, they are dominantly peraluminous to slightly metaluminous, subalkalic, relatively oxidized, and appear to span I-, S-, and A-type (within-plate) fields on various lithogeochemical discriminant plots. These new data will help constrain genetic and exploration models for a wide variety of Cretaceous intrusion-related gold and base metal mineral deposit types in the study area.

We present new field and U-Pb analytical data from the Sonora Gulch Project that demonstrate a protracted history of polymetallic mineralization (Au-Ag-Cu-Zn ± Mo) associated with several pulses of Cretaceous magmatism. Recent exploration on the Sonora Gulch Project has highlighted the presence of two important mineralized zones: the Nightmusic zone, a mesothermal Au-enriched base metal skarn, and the Amadeus zone, an epithermal Au-Ag system. Four U-Pb age dates determined from each of two feldspar porphyry dykes (ca. 74 Ma), a weakly mineralized quartz porphyry stock (ca. 75 Ma) within the Nightmusic zone and the Au-Ag mineralized Amadeus stock (ca. 75 Ma), demonstrate the widespread occurrence of Late Cretaceous magmatism. The age determinations indicate that mineralization occurring within the Sonora Gulch project area are temporally equivalent to the Casino Cu-Au-Mo deposit, located roughly 40 km to the west-northwest. These new data extend the currently known eastern limit of Late Cretaceous magmatism and associated mineralization.

Cassiterite (SnO2), a main ore mineral in tin deposits, was collected by multiple Russian geologists or obtained from museum collections in both the USA and Russia and dated at the U.S. Geological Survey. The dated samples represent four different mining districts spanning the entire country from the village of Pitkäranta in the west (31° E Longitude) to the Merekskoe Deposit in the Russian Far East (134°E Longitude). The samples were recovered from a variety of host deposit types that range from the Proterozoic to Phanerozoic. Cassiterite (in the form of mounted loose grains) was prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) system at the USGS in Denver, Colorado from February 2017 to October 2019. This data supports the following associated publication: Neymark, L.A., Larin, A.M., and Moscati, R.J., 2021, Pb-Pb and U-Pb dating of cassiterite by in situ LA-ICPMS: Examples spanning ~1.85 Ga to ~100 Ma deposits in Russia and implications for dating Proterozoic to Phanerozoic tin deposits, Minerals.

This dataset contains U-Pb isotopic data and associated ages of zircons within the lithologic framework of igneous, metaigneous, and metasedimentary rocks collected from the Seldovia quadrangle in southcentral Alaska. The samples were collected as part of geological mapping and research conducted from 2020 to 2023 and funded by the Mineral Resources Program of the U.S. Geological Survey. Zircon grains were separated and analyzed by GeoSep Services (GSS). All analyses were conducted between 2021 and 2023 using laser-ablation-inductively-coupled-plasma-mass spectrometry (LA-ICP-MS) techniques. Also described in this report are the major and trace element geochemical analyses for samples collected as part of the mapping project. Analyses were conducted by ALS Global. Major elements were determined from fused bead, acid digestion, and ICP-AES analysis. Loss on ignition (LOI) was determined by furnace or TGA. Also included are rubidium (Rb), strontium (Sr), samarium (Sm), and neodymium (Nd) analyses conducted by the ALS Scandinavia laboratory in Lulea, Sweden. Samples were prepared by alkali fusion. Sr was separated using Sr-specific column (TrisKem). Nd was separated from matrix first as sum of REE using a AG50-x8 column (AlfaAesar) and then from Sm on a Ln column (TrisKem).

This dataset contains U-Pb isotopic data and associated ages of zircons within the lithologic framework of igneous, metaigneous, and metasedimentary rocks collected from the Seldovia quadrangle in southcentral Alaska. The samples were collected as part of geological mapping and research conducted from 2020 to 2023 and funded by the Mineral Resources Program of the U.S. Geological Survey. Zircon grains were separated and analyzed by GeoSep Services (GSS). All analyses were conducted between 2021 and 2023 using laser-ablation-inductively-coupled-plasma-mass spectrometry (LA-ICP-MS) techniques. Also described in this report are the major and trace element geochemical analyses for samples collected as part of the mapping project. Analyses were conducted by ALS Global. Major elements were determined from fused bead, acid digestion, and ICP-AES analysis. Loss on ignition (LOI) was determined by furnace or TGA. Also included are rubidium (Rb), strontium (Sr), samarium (Sm), and neodymium (Nd) analyses conducted by the ALS Scandinavia laboratory in Lulea, Sweden. Samples were prepared by alkali fusion. Sr was separated using Sr-specific column (TrisKem). Nd was separated from matrix first as sum of REE using a AG50-x8 column (AlfaAesar) and then from Sm on a Ln column (TrisKem).