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Filters Date Range Past year (0) Past month (0) Past week (0) Past day (0) Custom range... To   Search Contacts Wypych, Alicja Benowitz, J.A. Freeman, L.K. Layer, P.W. Sicard, K.R. More... Tag Types Theme (12) Place (12) Tag Schemes Alaska Division of Geological & Geophysical Surveys (11) None (1) ISO 19115 Topic Category (12) View Results as: JSON ATOM CSV

Geology of Kasatochi volcano, Aleutian Islands, Alaska Kasatochi is a small, isolated island volcano in the center of the Aleutian Island chain. It consists of a roughly circular cone approximately 3 km in diameter with a lake-filled central crater that is 1.2 km in diameter and extends from the highest point on the island to sea level. The oldest unit recognized is a thick series of mid-Pleistocene glaciovolcanic deposits consisting of autobrecciated lava, lahars, and volumetrically minor lava masses that we believe to have been emplaced underneath a regional ice cap. This unit is unconformably overlain by several massive Holocene lavas, above which lies a thick sequence of latest-Holocene pyroclastic deposits likely deposited during the crater-forming eruption. The... Tags: Active Volcanoes, Age Dates, Aleutian Arc, Aleutian Islands, Alluvial Deposits, All tags... Analyses, Analyses and Sampling, Basalt, Bedrock, Bedrock Geology, Caldera, Chemistry, Colluvium, Erosion, Fan, Geochemical Data, Geochemistry, Geochronology, Geologic, Geologic Hazards, Geologic Map, Geological Process, Geology, Geomorphology, Hazards, Historic Eruption, Igneous, Kasatochi, Lava Flow, Mineralogy, Petrographic, Petrography, Petrology, Pumice, Pyroclastics, Rockfall, Rocks, Sample Location, Slope Instability, Slump, Soils, Surface, Surficial, Talus, Tephra, Topography, Ultramafic, Uplift, Volcanic, Volcanic Ash, Volcanic Eruption, Volcanic Rocks, Volcaniclastics, Volcanoes, Volcanology, geoscientificInformation, Fewer tags 40Ar/39Ar data, Styx River map area, Lime Hills C-1 Quadrangle, Alaska This DGGS Raw Data File presents 40Ar/39Ar age dating results for selected igneous rocks encountered in the Styx River area of the western Alaska Range. Crystallization ages on biotite and hornblende from plutonic rocks range from about ~60 to ~63 Ma, while a sericite alteration age in plutonic rocks altered by a dike swarm also is around ~63 Ma. Sericite alteration associated with a copper-molybdenum porphyry ranges from ~10 to ~11 Ma. Analyses were performed by the University of Alaska Fairbanks Geochronology Laboratory, and results were reported by Paul Layer and Jeff Benowitz. This data release includes the following products: a summary of sample collection methods, the laboratory report, analytical data tables... Tags: 40Ar/39Ar, Age Dates, Airborne Geophysical Survey, Alaska Range, Analyses and Sampling, All tags... Analytical Results, Ar-Ar, Bedrock Geology, Copper, Economic Geology, Faults, Fracturing, Geochronology, Geology, Gold, Hornblende, K-Feldspar, Lab Methods, Lime Hills Quadrangle, Mica, Mineral Deposit, Mineral Prospect, Mineralogy, Minerals, Mining, Mining Claims, Molybdenite, Muscovite, Ore Deposit Model, Plutonic Rocks, Plutons, Polymetallic Vein, Porphyry, Pyrite, Pyrrhotite, Quartz, Sample Location, Sericite, Sericite Alteration, Styx River, Volcanic Rocks, geoscientificInformation, Fewer tags 40Ar/39Ar data from rocks collected in the 2015 Wrangellia mineral assessment project area, Mount Hayes A-5, Mount Hayes B-6, and Talkeetna Mountains D-2 quadrangles, Alaska This report presents 40Ar/39Ar step-heating geochronology results for igneous and metamorphic rocks from the Alaska Division of Geological & Geophysical Surveys' (DGGS) Wrangellia Mineral Assessment project, part of a multi-year effort focusing on improving the publicly available geoscientific information for the western Wrangellia terrane. The samples described in this report were selected and analyzed to improve our understanding of the geology and structural history of the Wrangellia Mineral Assessment project area. A metagabbro rock sample returned a Late Triassic crystallization age consistent with regional ages for Nikolai Greenstone-related magmatism; however, the two amphibole separates ages do not overlap,... Tags: 40Ar/39Ar, Analyses, Analyses and Sampling, Analytical Lab Results, Analytical Results, All tags... Ar-Ar, Basalt, Bedrock, Bedrock Geology, Copper, Crystals, Geochronology, Geologic, Geology, Greenstone, Hayes, Hornblende, Igneous, Igneous Rocks, Interpretation, Lab Methods, Methods, Mica, Mineral Composition, Mineral Resources, Mineralogy, Minerals, Mount Hayes Quadrangle, Muscovite, Plutonic Rocks, Porphyry, Resources, Rocks, Sample Location, Strategic Minerals, Strategic and Critical Minerals Assessment Project, Stratigraphy, Structural Geology, Talkeetna, Talkeetna Mountains, Talkeetna Mountains Quadrangle, Thrust, Volcanic Rocks, geoscientificInformation, Fewer tags Geologic map of the Circle mining district, Alaska This report provides detailed (1:63,360-scale) mapping of portions of U.S. Geological Survey Circle B-2 (1955), B-3 (1955), B-4 (1952), C-2 (1955), C-3 (1955), and C-4 (1952) quadrangles. The area is part of the Circle mining district and adjacent to the Fairbanks mining district. This report includes detailed geologic, structural, stratigraphic, and geochronologic data. Based on the resulting geologic maps, field investigations, and laboratory materials analyses, the project has also generated derivative maps of geologic construction materials and geologic hazards. Tags: Aereal, Aerial Photography, Aeromagnetic Survey, Age Dates, Alaska, State of, All tags... Alluvial Deposits, Alluvium, Amphibolite, Ar-Ar, Bedrock, Bibliography, Birch Creek, C14, Carbonates, Circle Hot Springs, Circle Mining District, Circle Quadrangle, Clastics, Coal, Colluvial Deposits, Colluvium, Conductivity Survey, Conodonts, Crooked Creek, Electromagnetic Survey, Fan, Faulting, Faults, Fluvial, Folding, Fossils, Geologic, Geomorphology, Glacial, Glacial Deposits, Glacial Drift, Granite, Hornblende, Hornfels, Igneous Rocks, K-Ar, Magnetite, Major Oxides, Mammoth Creek, Mastodon Dome, Metamorphic Grade, Metamorphic Minerals, Metamorphism, Mineralogy, Modal Analysis, Petrography, Plutonic, Plutonic Hosted, Porphyry, Precious Metals, Quartz, Regional, Regional Metamorphism, Sample Location, Sandstone, Schist, Sedimentary, Structure, Surficial, Tectonics, Terranes, 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 Petrology and reservoir potential of Tertiary and Mesozoic sandstones, Cook Inlet, Alaska: A preliminary analysis of outcrop samples collected during 2007-2010 field seasons The State of Alaska Division of Geological & Geophysical Surveys (DGGS) and Division of Oil & Gas (DOG) are currently engaged in a multi-year study of the hydrocarbon potential of the Tertiary and Mesozoic strata in Cook Inlet basin. Modal analyses and routine core analyses were performed on Tertiary and Mesozoic siltstones and sandstones collected during the 2007-2010 field seasons from six geographic areas in upper and lower Cook Inlet. The reservoir quality of Cook Inlet sandstones varies widely depending on their mineralogy, geologic age, burial depth, and depositional environment. Tuxedni and Naknek sandstones have poor reservoir quality and are likely to be of equally poor quality down dip. West Foreland sandstones... Tags: Aleutian Arc, Beluga Basin, Bluff Point, Capps Glacier, Chert, All tags... Chuitna River, Clam Gulch, Cook Inlet, Cook Inlet Basin, Diagenesis, Falls Creek, Feldspar, Fritz Creek, Graywacke, Homer, Iniskin Bay, Iniskin Peninsula, Kachemak Bay, Kaguyak, Matanuska Valley, Mineralogy, Oil Basins, Oil and Gas, Oil and Gas Basin, Outcrop Samples, Permeability, Petrographic, Petrography, Petroleum Basin Study, Petrology, Porosity, Provenance, Pyroclastic Fall, Pyroclastic Flow, Quartz, Reservoir, Reservoir Evaluation, Reservoir Quality, Resource Assessment, Saddle Mountain, Sample Location, Sample Location Map, Sand, Sand and Gravel, Sediment Transport, Sedimentary, Sedimentary Rocks, Sedimentation, Sedimentology, Seward Peninsula, Southcentral Alaska, Straight Creek, Tectonics, Thin Section, Tyonek, Tyonek Quadrangle, Volcanic, Volcanic Ash, Volcaniclastics, Zeolites, geoscientificInformation, Fewer tags Major-oxide, minor-oxide, and trace-element geochemical data from rocks collected in 2008 in the eastern Bonnifield mining district, Fairbanks and Healy quadrangles, Alaska Mineral-resources personnel from the Alaska Division of Geological & Geophysical Surveys carried out a geological field survey, including mapping and sampling, in the eastern part of the Bonnifield mining district in the Fairbanks A-1 and A-2, and the Healy D-1 and D-2 quadrangles, Alaska, from June 16 through July 18, 2008. The fieldwork provides basic information critical to building an understanding of Alaska's geology and is part of an integrated program of airborne geophysical surveys followed by geological mapping. Specifically, this work provides geologic context for geophysical surveys conducted in 2006. To represent a typical lithology, igneous or possible meta-igneous samples were collected and analyzed... Tags: Alaska Range, Analyses, Analyses and Sampling, Analytical Lab Results, Analytical Results, All tags... Bedrock, Bedrock Geology, Chemistry, Chute Creek, Dry Creek, Fairbanks Quadrangle, Geochemical Data, Geochemical Surveys, Geochemistry, Geologic, Geology, Healy Quadrangle, Igneous, Igneous Rocks, Kansas Creek, Lab Methods, Metamorphic Rocks, Methods, Mineral Assessment, Mineralogy, Minerals, Red Mountain Creek, Resource Assessment, Resource Information, Resources, Rocks, Rogers Creek, STATEMAP Project, Sample Location, Sheep Creek, geoscientificInformation, Fewer tags 40Ar/39Ar data from the Tok River area, Tanacross A-5 and A-6 quadrangles and adjoining areas, eastern Alaska Range This report presents 40Ar/39Ar step-heating geochronology results for igneous and metamorphic rocks from the Alaska Division of Geological & Geophysical Surveys' (DGGS) geologic mapping project in the Tanacross A-5 and A-6 quadrangles and adjoining areas. Our results indicate the Hona granodiorite pluton intruded the area in the Late Cretaceous between 76 and 71 Ma. We determined Cretaceous metamorphic ages from 126 to 121 Ma for hornblende, biotite, sericite and muscovite from multiple samples of upper greenschist to amphibolite grade rocks. This is consistent with regional argon results that imply this area is in the upper plate of the Yukon Tanana Terrane (Hansen and Dusel-Bacon, 1998). Basaltic andesite dikes... Tags: 40Ar/39Ar, Amphibolite, Analyses, Analyses and Sampling, Analytical Lab Results, All tags... Analytical Results, Basalt, Bedrock, Crystals, Exploration, Faulting, Geochronology, Geologic, Geology, Gneiss, Granite, Granodiorite, Greenschist, Hornblende, Igneous, Isotopes, Metamorphic, Metamorphic Rocks, Metamorphism, Methods, Mica, Mineral Composition, Mineral Prospect, Mineralogy, Minerals, Muscovite, Noah Prospect, Plagioclase, Plutonic, Rocks, Sample Location, Sericite, Shalosky Prospect, Tanacross Quadrangle, Tok, Tok Mining District, Tok River, geoscientificInformation, Fewer tags 40Ar/39Ar ages of rocks collected from the Passage Canal area, Seward D-7 Quadrangle, Alaska This report presents 40Ar/39Ar step-heating geochronology results from a single outcrop of a mineralized near-trench intrusion exposed in a road cut near Whittier, Alaska. The outcrop is the best road-accessible occurrence of a Tertiary near-trench pluton in the region and is commonly visited by field trips, yet no prior geochronological data from this outcrop have been published. Two chronologically distinct intrusive bodies, the Paleogene Sanak-Baranof belt and the Eshamy-suite, are documented in the upper Cook Inlet area. Geochronological analysis of the two samples described in this report confirms that the Whittier road-cut intrusion and veins are coeval (53.0 +/- 0.3 Ma and 50.9 +/- 0.2 Ma, respectively) with... Tags: 40Ar/39Ar, Age Dates, Analyses, Analyses and Sampling, Analytical Lab Results, All tags... Analytical Results, Ar-Ar, Bedrock, Bedrock Geology, Geochronology, Geologic, Geology, Igneous, Igneous Rocks, Isotopes, Lab Methods, Methods, Mineralogy, Rocks, Sample Location, Seward Quadrangle, Volcanic Arc, Volcanic Rocks, Whittier, geoscientificInformation, Fewer tags Major-oxide and trace-element geochemical data from rocks collected near Panorama Mountain, Mile 104 Seward Highway, Crow Pass, and Whittier, Alaska In conjunction with hosting field trips for the Association of American State Geologists 2016 annual meeting in Girdwood, Alaska, Alaska Division of Geological & Geophysical Surveys (DGGS) staff collected rock samples and obtained geochemical analysis from several readily accessible, but relatively unstudied outcrops. Samples were collected from Turnagain Arm (mile 104 Seward Highway), Whittier, Crow Pass, and Panorama Mountain (roughly mile 217 Parks Highway). Mineralized samples from veins and veinlets in granitic rocks from the Crow Pass and Whittier sites contain anomalous levels of gold ranging from 0.129 to 0.650 parts per million (ppm). Although none of the samples are from areas open to mineral entry, geochemical... Tags: Analyses, Analyses and Sampling, Analytical Lab Results, Analytical Results, Base Metals, All tags... Bedrock, Bedrock Geology, Chemistry, Economic Geology, Exploration, Geochemical Data, Geochemical Surveys, Geochemistry, Geologic, Geologic Map, Geology, Gold, Gold Prospect, Heavy Metals, Igneous, Igneous Rocks, Lab Methods, Magmatic Arc, Major Oxides, Metallogenesis, Metals, Mineral Assessment, Mineral Deposit, Mineral Development, Mineral Localities, Mineral Prospect, Mineral Resources, Mineralogy, Minerals, Mining, Minor Oxides, Ore Deposit, Ores, Petrology, Plutonic, Plutonic Hosted, Plutonic Rocks, Plutons, Precious Metals, Resource Assessment, Resource Information, Resources, Sample Location, Southcentral Alaska, Trace Elements, Trace Geochemical, Trace Metals, Whittier, geoscientificInformation, Fewer tags Geology of Kasatochi volcano, Aleutian Islands, Alaska Kasatochi is a small, isolated island volcano in the center of the Aleutian Island chain. It consists of a roughly circular cone approximately 3 km in diameter with a lake-filled central crater that is 1.2 km in diameter and extends from the highest point on the island to sea level. The oldest unit recognized is a thick series of mid-Pleistocene glaciovolcanic deposits consisting of autobrecciated lava, lahars, and volumetrically minor lava masses that we believe to have been emplaced underneath a regional ice cap. This unit is unconformably overlain by several massive Holocene lavas, above which lies a thick sequence of latest-Holocene pyroclastic deposits likely deposited during the crater-forming eruption. The... Tags: Active Volcanoes, Age Dates, Aleutian Arc, Aleutian Islands, Alluvial Deposits, All tags... Analyses, Analyses and Sampling, Basalt, Bedrock, Bedrock Geology, Caldera, Chemistry, Colluvium, Erosion, Fan, Geochemical Data, Geochemistry, Geochronology, Geologic, Geologic Hazards, Geologic Map, Geological Process, Geology, Geomorphology, Hazards, Historic Eruption, Igneous, Kasatochi, Lava Flow, Mineralogy, Petrographic, Petrography, Petrology, Pumice, Pyroclastics, Rockfall, Rocks, Sample Location, Slope Instability, Slump, Soils, Surface, Surficial, Talus, Tephra, Topography, Ultramafic, Uplift, Volcanic, Volcanic Ash, Volcanic Eruption, Volcanic Rocks, Volcaniclastics, Volcanoes, Volcanology, geoscientificInformation, Fewer tags Major-oxide and trace-element geochemical data from rocks collected near Panorama Mountain, Mile 104 Seward Highway, Crow Pass, and Whittier, Alaska In conjunction with hosting field trips for the Association of American State Geologists 2016 annual meeting in Girdwood, Alaska, Alaska Division of Geological & Geophysical Surveys (DGGS) staff collected rock samples and obtained geochemical analysis from several readily accessible, but relatively unstudied outcrops. Samples were collected from Turnagain Arm (mile 104 Seward Highway), Whittier, Crow Pass, and Panorama Mountain (roughly mile 217 Parks Highway). Mineralized samples from veins and veinlets in granitic rocks from the Crow Pass and Whittier sites contain anomalous levels of gold ranging from 0.129 to 0.650 parts per million (ppm). Although none of the samples are from areas open to mineral entry, geochemical... Tags: Analyses, Analyses and Sampling, Analytical Lab Results, Analytical Results, Base Metals, All tags... Bedrock, Bedrock Geology, Chemistry, Economic Geology, Exploration, Geochemical Data, Geochemical Surveys, Geochemistry, Geologic, Geologic Map, Geology, Gold, Gold Prospect, Heavy Metals, Igneous, Igneous Rocks, Lab Methods, Magmatic Arc, Major Oxides, Metallogenesis, Metals, Mineral Assessment, Mineral Deposit, Mineral Development, Mineral Localities, Mineral Prospect, Mineral Resources, Mineralogy, Minerals, Mining, Minor Oxides, Ore Deposit, Ores, Petrology, Plutonic, Plutonic Hosted, Plutonic Rocks, Plutons, Precious Metals, Resource Assessment, Resource Information, Resources, Sample Location, Southcentral Alaska, Trace Elements, Trace Geochemical, Trace Metals, Whittier, geoscientificInformation, Fewer tags