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A physiographically prominent, approximately 40 square km plateau lies roughly 20 km east of Mount Spurr volcano, northwestern Cook Inlet region, Alaska, and comprises the preserved remnant of a volcaniclastic succession, designated in this study as map unit Qvc. Although this readily mappable package of volcaniclastic rocks has been recognized in numerous studies during the past five decades, uncertainties regarding its age and origin have persisted. We describe the general characteristics of the volcaniclastic plateau, provide new age constraints for deposits, present lithofacies descriptions and interpretations of the volcaniclastic strata, and synthesize our observations and lithofacies analysis to propose an...
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Twenty-two igneous and metamorphic rock samples were collected in a 20-km-long swath centered on the Alaska Highway between Tetlin Junction, Alaska, and the Canada border. Igneous and metamorphic rock samples were submitted to the Apatite to Zircon, Inc. laboratory (A2Z), where zircon U-Pb age analysis, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), was performed by Paul O'Sullivan. The 15 felsic plutonic rock samples and one gabbro sample yield Cretaceous zircon U-Pb weighted-mean ages ranging from 95.7 Ma to 106.2 Ma. Zircons from a metadiorite yield a Triassic weighted-mean age of about 241.9 Ma. Metamorphic zircons from two samples with felsic igneous protoliths yield Mississippian...
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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 dataset accompanies the publication, 'In situ LA-ICPMS U-Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to Tertiary', published in Chemical Geology (https://doi.org/10.1016/j.chemgeo.2018.03.008), which reports a LA-ICPMS analytical procedure for dating cassiterite, a main ore mineral in tin deposits, with no need for an independently dated matrix-matched cassiterite standard.
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We report U-Pb zircon geochronology results for one metavolcanic and one metaplutonic rock sample from the Mount Hayes A-6 Quadrangle of central Alaska. These samples are representative of rock units assigned to the Clearwater terrane of Jones and others (1987), a sequence of greenschist-grade metavolcanic and metasedimentary rocks of poorly constrained age and tectonic origin. Our results indicate a crystallization age of 277.33 +/- 11.84 Ma for a felsic metavolcanic rock, and a 268.05 +/- 11.64 Ma crystallization age for a granitic metaplutonic unit intruding the former.
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This data release presents zircon U-Pb LA-ICP-MS geochronology from igneous rocks exposed in a coastal exposure at Ursus Head, Iliamna C-2 Quadrangle. Sills and dikes exposed in a coastal exposure at Ursus Head are deformed within the Bruin Bay fault zone. Common dikes intruding late Triassic Kamishak Formation strata composing the hanging-wall of the Bruin Bay fault are cut by numerous small-scale, low-angle, bedding-parallel, and high angle contractional faults. Sample 09MAW006A collected from one of many dikes deformed in the fault zone produced a uni-modal distribution of zircon ages of with a weighted mean of 206.92 +/-0.96 (2 sigma, n=47) and an MSWD of 1.1. Sample 09BG020C collected from a sill of more mafic...
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Instrument, standard, and sample data from application of in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) dating of scheelite in thin section, and sample data from isotope dilution thermal ionization mass spectrometry (ID-TIMS) scheelite dating are in this data release. Fractionation factor and ratio data in between NIST glass and natural scheelite as well as isotope dilution Sm-Nd scheelite data are also included. Scheelite is from two ore deposits within the Stibnite-Yellow Pine mining area, and analyses yielded bimodal U-Pb ages with major growth of scheelite in the range of 61.3 ± 4.1 to 55.1 ± 3.8 Ma and a second growth event involving both scheelite and stibnite at 45.8 ± 2.6...
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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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U-Pb analyses were performed on igneous rocks from the Ray Mountains area of west-central Alaska. These new age analyses will allow us to better evaluate the geochronology of the granitic rocks that are the apparent source of the alluvial REE and tin resources. The plutonic samples have ages ranging from 98.0 +/- 0.9 Ma to 111.6 +/- 1.0 Ma. The sample location coordinates and analytical data tables associated with this report are available in digital format as comma-separated value (CSV) files.
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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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Cassiterite (SnO2) samples were collected from alluvial ore concentrate from the Abu Dabbab Granite in eastern Egypt. Samples (in the form of mounted loose grains) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) system at the U.S. Geological Survey in Denver, Colorado in February 2019. This data release accompanies the publication, 'Monazite and cassiterite U-Pb dating of the Abu Dabbab rare-metal granite, Egypt: Late Cryogenian metalliferous granite magmatism in the Arabian-Nubian Shield.' (Lehmann and others, 2020). The publication constrains the timing of the magmatic-hydrothermal processes of the Abu Dabbab Granite which represents...
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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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Geologic mapping, characterization of geologic structures, and sampling for geochronology was completed in two areas of the northwestern Sangre de Cristo Mountains from 2011 through 2017. This data release provides the raw analytical data, metadata and sample information for 20 zircon U-Pb age analyses from laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The two areas include the Poncha Pass area where the entire 71/2’ Poncha Pass quadrangle and parts of five other quadrangles (Mount Ouray, Maysville, Salida West, Salida East, and Wellsville) were mapped at a scale of 1:24,000 (see Minor and others, 2019). The Deadman thrust fault is the second area, approximately 80 km southwest of the Poncha...
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This Division of Geological & Geophysical Surveys (DGGS) Raw Data File presents U-Pb geochronology and Lu-Hf isotopic compositions, age-dating results, and additional trace-elemental composition of zircons from four granitoids sampled during investigations by DGGS geologists in the western Alaska Range and the Talkeetna Mountains. The purpose of the Lu-Hf and U-Pb isotopic study was to better understand the Jurassic through early Tertiary magmatic and tectonic evolution of the Alaska Range and the significance of that magmatism for the formation of metallic mineral deposits. The U-Pb isotopic data also serve to further refine the crystallization age of plutons, which were previously ambiguous in 40Ar/39Ar geochronology...
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Cassiterite (SnO2) samples were collected throughout Devon and Cornwall Counties in southwest England, United Kingdom. Samples were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) system at the U.S. Geological Survey in Denver, Colorado in February and April 2018. This data release accompanies the publication, 'U-Pb geochronology of tin deposits associated with the Cornubian Batholith of southwest England: Direct dating of cassiterite by in situ LA-ICPMS' (Moscati and Neymark, in press). The publication describes a greater chronologic control and refinement of Cornubian tin ore deposition and allows comparison of its timing with previously published...
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Cassiterite (SnO2) samples were collected throughout the underground Sullivan Mine near Kimberley, British Columbia. Samples (in the form of mounted loose grains, polished thin sections, and rock mounts) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) system at the U.S. Geological Survey in Denver, Colorado in February and April 2018. This data release accompanies the publication, 'Origin of Tin Mineralization in the Sullivan Pb-Zn-Ag Deposit, British Columbia: Constraints from Textures, Geochemistry, and LA-ICP-MS U-Pb Geochronology of Cassiterite.' (Slack and others, 2020). The publication constrains the timing of cassiterite ore mineralization...
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Apatite [Ca5(PO4)3F], titanite [CaTiSiO5], and rutile [TiO2] samples were collected by the U.S. Geological Survey (USGS) from the Coles Hill uranium deposit, Virginia. The samples (in the form of polished thin sections) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA–ICPMS) system at the USGS in Denver, Colorado from August 2017 to March 2019.
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Zircon (ZrSiO4) and cassiterite (SnO2) samples were collected by the U.S. Geological Survey (USGS) from the Yazov Granite, Transbaikalia region, Eastern Siberia, Russia. Samples (in the form of mounted loose grains) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA–ICPMS) system at the USGS in Denver, Colorado from February 2017 to June 2019. The data indicate that high tin concentrations in the Yazov Granite are caused by inheritance of older cassiterite crystals and may imply that these granites cannot be genetically related to primary tin ore deposits of the region. These results have broad implications in understanding how critical elements,...
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This data release presents 40Ar/39Ar step-heating geochronology results from rocks collected roughly 7 km southwest of Contact Point, Iliamna B-3 Quadrangle. Samples obtained from a felsic dike intruding the principal Bruin Bay fault plane near Contact Point produced biotite and plagioclase 40Ar/39Ar ages of 36.5 +/- 0.8 Ma and 31.5+/-0.7 Ma, respectively. The age dates inform stratigraphic, structural, and geochronologic studies along the western margin of lower Cook Inlet basin. The accompanying report also presents zircon U-Pb LA-ICP-MS geochronology results for dikes near Ursus Head.


    map background search result map search result map Zircon U-Pb age data, Alaska Highway Corridor, Tanacross and Nabesna quadrangles, Alaska Zircon U-Pb age data, Ray Mountains area, Bettles Quadrangle, Alaska U-Pb zircon age data from meta-igneous rocks in the Clearwater Mountains, Mount Hayes A-6 Quadrangle, Alaska U-Pb and Lu-Hf isotope, age, and trace-element data from zircons at four sites in the western Alaska Range and Talkeetna Mountains, Alaska Zircon U-Pb and 40Ar/39Ar results from dikes collected within the Bruin Bay fault zone, lower Cook Inlet Zircon U-Pb and 40Ar/39Ar results from dikes collected within the Bruin Bay fault zone, lower Cook Inlet Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska U-Pb data for: In situ LA-ICPMS U-Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to Tertiary U-Pb data for: U-Pb geochronology of tin deposits associated with the Cornubian Batholith of southwest England: Direct dating of cassiterite by in situ LA-ICPMS U-Pb detrital zircon data for: Select Pennsylvanian-Triassic sedimentary rocks from Colorado U-Pb zircon data for: The Poncha Pass and Deadman Creek areas, northern Sangre de Cristo Mountains of south-central Colorado U-Pb detrital zircon geochronology of cores and cuttings from selected wells in Arctic Alaska U-Pb detrital zircon data for: lower Paleozoic sedimentary rocks near Silverton, CO USA U-Pb zircon data for: Cretaceous plutonic rocks of western Glacier Bay National Park and Preserve U–Pb data for Origin of Tin Mineralization in the Sullivan Pb-Zn-Ag Deposit, British Columbia: Constraints from Textures, Geochemistry, and LA-ICP-MS U-Pb Geochronology of Cassiterite U-Pb data for: Monazite and cassiterite U-Pb dating of the Abu Dabbab rare-metal granite, Egypt: Late Cryogenian metalliferous granite magmatism in the Arabian-Nubian Shield U-Pb data for inherited cassiterite in "Tin Granites", an example from the Yazov Granite, Eastern Siberia U-Pb data for the Coles Hill uranium deposit, Virginia Isotopic ratios and element concentrations of U-Pb and Sm-Nd for scheelite petrochronology Zircon U-Pb and 40Ar/39Ar results from dikes collected within the Bruin Bay fault zone, lower Cook Inlet Isotopic ratios and element concentrations of U-Pb and Sm-Nd for scheelite petrochronology Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska U-Pb zircon age data from meta-igneous rocks in the Clearwater Mountains, Mount Hayes A-6 Quadrangle, Alaska U-Pb data for: Monazite and cassiterite U-Pb dating of the Abu Dabbab rare-metal granite, Egypt: Late Cryogenian metalliferous granite magmatism in the Arabian-Nubian Shield U-Pb zircon data for: Cretaceous plutonic rocks of western Glacier Bay National Park and Preserve U–Pb data for Origin of Tin Mineralization in the Sullivan Pb-Zn-Ag Deposit, British Columbia: Constraints from Textures, Geochemistry, and LA-ICP-MS U-Pb Geochronology of Cassiterite U-Pb data for the Coles Hill uranium deposit, Virginia Zircon U-Pb age data, Alaska Highway Corridor, Tanacross and Nabesna quadrangles, Alaska U-Pb data for: U-Pb geochronology of tin deposits associated with the Cornubian Batholith of southwest England: Direct dating of cassiterite by in situ LA-ICPMS U-Pb data for inherited cassiterite in "Tin Granites", an example from the Yazov Granite, Eastern Siberia U-Pb and Lu-Hf isotope, age, and trace-element data from zircons at four sites in the western Alaska Range and Talkeetna Mountains, Alaska U-Pb detrital zircon data for: Select Pennsylvanian-Triassic sedimentary rocks from Colorado U-Pb detrital zircon geochronology of cores and cuttings from selected wells in Arctic Alaska U-Pb data for: In situ LA-ICPMS U-Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to Tertiary