The data are the results of mass spectrometer experiments to measure 40Ar/39Ar ages of sanidine crystals hosted in Yellowstone rhyolites. The data were collected using a MAP216 noble gas mass spectrometer and a Nu Noblesse noble gas mass spectrometer at the USGS facility in Menlo Park, Calif.

A copy of this thesis is available at the EMR library – TN785 L42 1973. This thesis is available online at http://hdl.handle.net/2429/32084.

The Quartz Lake sedimentary hosted lead-zinc occurrence is 70 km northeast of Watson Lake. Proterozoic rocks of the area are divided into three groups of argillite, quartzite and limestone which are, in stratigraphic succession from oldest to youngest, the Range Group, the Mine Group and the Ridge Group. There are two principal lead-zinc occurrences in rocks of the Mine Group where pyrite, sphalerite and galena occur in tabular bodies, lenses and disseminations in a predominantly quartzite host rock.

LA-ICP-MS uranium lead geochronologic data of zircon from igneous and meta-igneous rocks in the Chena project area, Circle, Big Delta, and Eagle quadrangles, Alaska, Raw Data File 2025-14, provides uranium-lead (U-Pb) geochronologic data from single zircon spots, analyzed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Alaska Division of Geological & Geophysical Surveys (DGGS) staff collected zircon data from 22 igneous and meta-igneous rock samples, primarily collected during the 2023 field season, to support the Earth Mapping Resources Initiative (Earth MRI) Chena project. Two samples were analyzed to support geologic interpretation in the Mount Harper (2022) project area. Crystallization age data are organized in the age summary data table with our interpreted crystallization ages, sample location information, and sample descriptions. The zircon grain data table contains isotopic and elemental data for each zircon spot analyzed. Both tables have accompanying data dictionaries. These data and report are available from the DGGS website: http://doi.org/10.14509/31553.

The 1.71 Ga Bonnet Plume River intrusions (BPRI) and related volcanics are preserved only as clasts in the 1.60 Ga Wernecke breccias of Yukon that host iron-oxide copper gold (IOCG) occurrences. Field work conducted in 2009 confirmed that they did not intrude the surrounding <1.64 Ga Wernecke Supergroup. Petrography shows that they are extensively altered and/or metasomatized, although relicts of primary igneous minerals remain. The major oxides are of little use in classification. Trace element geochemistry however, reveals a mafic to intermediate, calc-alkaline volcanic arc signature. Geochemical modelling has demonstrated that crystal fractionation was dominated by pyroxenes, plagioclase and olivine. The BPRI and related volcanic rocks are thought to have originated in a calc-alkaline volcanic arc that was obducted onto the Wernecke Supergroup, subsequently partially brecciated, and finally sank within the Wernecke breccias to the level of the Wernecke Supergroup.

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.

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.

LA-ICP-MS uranium-lead geochronologic data of detrital zircon from a metamorphic rock in the northern Fairbanks mining district, Circle Quadrangle, Alaska, Raw Data File 2025-16, provides uranium-lead (U-Pb) geochronologic single spot zircon data, analyzed using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The detrital zircon (DZ) data come from a metamorphic rock from the Alaska Division of Geological & Geophysical Surveys' (DGGS) geologic mapping project in the northern Fairbanks mining district, covering parts of the Circle A-4, A-5, B-4, and B-5 quadrangles, Alaska. Sample 07JEA354a was collected by the DGGS Mineral Resources Section during a detailed geologic mapping campaign in June 2007. The zircon grain data table contains isotopic and elemental data for each zircon spot analyzed. Both tables have accompanying data dictionaries. These data and report are available from the DGGS website: http://doi.org/10.14509/31685.