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Filters Date Range Past year (0) Past month (0) Past week (0) Past day (0) Custom range... To   Search Contacts O'Sullivan, P.B. Gillis, R.J. Wartes, M.A. Benowitz, J.A. Freeman, L.K. More... Tag Types Theme (7) Place (7) Tag Schemes Alaska Division of Geological & Geophysical Surveys (7) ISO 19115 Topic Category (7) View Results as: JSON ATOM CSV

Zircon U-Pb age data, Alaska Highway Corridor, Tanacross and Nabesna quadrangles, Alaska 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... Tags: Age Dates, Alaska Highway Corridor, Analyses and Sampling, Bedrock, Bedrock Geology, All tags... Detrital Zircon, Geochronology, Geology, Igneous Rocks, Isotopes, Metamorphic Rocks, Nabesna Quadrangle, Tanacross Quadrangle, U-Pb, geoscientificInformation, Fewer tags Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska 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... Tags: Age Dates, Alluvial, Alluvial Deposits, Bedrock, Bedrock Geology, All tags... Capps Glacier, Debris Flow, Debris Flow Deposit, Depositional Environment, Depositional Environments, Detrital Zircon, Facies Analysis, Geochronology, Geological Process, Geology, Lahar, Lahar Runout Flow, Liquefaction, Mount Spurr, Paleoenvironment, Paleogeography, STATEMAP Project, Sediment Transport, Sedimentary, Sedimentary Rocks, Sedimentation, Sedimentology, Tyonek Quadrangle, U-Pb, Volcaniclastics, geoscientificInformation, Fewer tags U-Pb zircon age data from meta-igneous rocks in the Clearwater Mountains, Mount Hayes A-6 Quadrangle, Alaska 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. Tags: Age Dates, Analyses, Analyses and Sampling, Analytical Lab Results, Bedrock, All tags... Bedrock Geology, Geochronology, Geology, Lab Methods, Metamorphic Rocks, Metavolcanic rocks, Mount Hayes Quadrangle, Orthogneiss, Sample Location, U-Pb, Zircon, geoscientificInformation, Fewer tags Zircon U-Pb and 40Ar/39Ar results from dikes collected within the Bruin Bay fault zone, lower Cook Inlet 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... Tags: 40Ar/39Ar, Age Dates, Analyses, Analyses and Sampling, Analytical Lab Results, All tags... Analytical Results, Ar-Ar, Bedrock, Bedrock Geology, Contact Point, Cook Inlet, Cook Inlet Basin, Fault Displacement, Geochronology, Geologic, Geology, Igneous, Iliamna Quadrangle, Isotopes, Lab Methods, Lead, Methods, Naknek, Plagioclase, Rocks, Sample Location, Stratigraphy, Structural Geology, Structure, Tectonics, U-Pb, Uranium, Ursus Head, Volcanic, Volcanic Rocks, Zircon, geoscientificInformation, Fewer tags Zircon U-Pb age data, Ray Mountains area, Bettles Quadrangle, Alaska 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. Tags: Age Dates, Analyses, Analyses and Sampling, Analytical Lab Results, Analytical Results, All tags... Bedrock, Bedrock Geology, Bettles Quadrangle, Geochronology, Geology, Igneous Rocks, Lab Methods, Metals, Mineral Assessment, Mineral Deposit, Mineral Resources, Minerals, Plutonic, Polymetallic, Rare Earth Elements, Ray Mountains, Sample Location, Strategic and Critical Minerals Assessment Project, Tin, U-Pb, Zircon, geoscientificInformation, Fewer tags 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 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... Tags: Age Dates, Alaska Range, Analyses, Analyses and Sampling, Analytical Lab Results, All tags... Analytical Results, Bedrock, Geochemistry, Geochronology, Geologic, Geology, Geophysics, Granite, Hafnium, Isotopes, Lab Methods, Lead, Lime Hills Quadrangle, Lutetium, Methods, Mineralogy, Minerals, Plutonic, Plutons, Resources, Rocks, STATEMAP Project, Talkeetna Mountains, Talkeetna Mountains Quadrangle, Trace Elements, U-Pb, Uranium, Zircon, geoscientificInformation, Fewer tags Zircon U-Pb and 40Ar/39Ar results from dikes collected within the Bruin Bay fault zone, lower Cook Inlet 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. Tags: 40Ar/39Ar, Age Dates, Analyses, Analyses and Sampling, Analytical Lab Results, All tags... Analytical Results, Ar-Ar, Bedrock, Bedrock Geology, Contact Point, Cook Inlet, Cook Inlet Basin, Fault Displacement, Geochronology, Geologic, Geology, Igneous, Iliamna Quadrangle, Isotopes, Lab Methods, Lead, Methods, Plagioclase, Rocks, Sample Location, Stratigraphy, Structural Geology, Structure, Tectonics, U-Pb, Uranium, Ursus Head, Volcanic, Volcanic Rocks, Zircon, geoscientificInformation, Fewer tags