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Filters Date Range Past year (0) Past month (0) Past week (0) Past day (0) Custom range... To   Search Contacts Layer, P.W. Benowitz, J.A. Freeman, L.K. Newberry, R.J. Twelker, Evan More... Tag Types Theme (26) Place (26) Tag Schemes Alaska Division of Geological & Geophysical Surveys (25) None (1) ISO 19115 Topic Category (26) 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 40Ar/39Ar data, Ray Mountains area, Bettles Quadrangle, Alaska 40Ar/39Ar analyses were performed on igneous rocks from the Ray Mountains area of west-central Alaska. The plutonic samples have ages from about 89 Ma to 109 Ma, while the volcanic samples show ranges from about 30 Ma to 64 Ma. The three volcanic samples fall into two age groups: the younger sample, a basalt, has an age of about 30 Ma, while the two older, rhyolitic samples fall between 58 Ma and 64 Ma. Analyses were performed by the University of Alaska Fairbanks Geochronology Laboratory, and results were reported by Paul Layer and Jeff Benowitz. Products included in this data release are: a summary of sample collection method; the laboratory report, analytical data tables and associated metadata; and plots of... Tags: 40Ar/39Ar, Age Dates, Analyses, Analyses and Sampling, Analytical Lab Results, All tags... Analytical Results, Ar-Ar, Bedrock, Bedrock Geology, Bettles Quadrangle, Geochronology, Geology, Lab Methods, Mineral Assessment, Mineral Deposit, Mineral Resources, Ray Mountains, Sample Location, Strategic and Critical Minerals Assessment Project, 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 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 Geologic map of portions of the Livengood B-3, B-4, C-3, and C-4 quadrangles, Tolovana mining district, Alaska This data file presents 40Ar/39Ar step-heating geochronology results for a granite sample from the Livengood mining district. The Livengood area is a historically productive placer mining area approximately 80 road miles north of Fairbanks, Alaska. This data is a component of a geologic map and accompanying report that synthesizes recently collected and previously published agency and industry geologic data in a 1:50,000-scale comprehensive geologic map to build a better understanding of the geology and mineral-resource potential of the Livengood area. Tags: 40Ar/39Ar, Airborne Geophysical/Geological Mineral Inventory, Bedrock, Bedrock Geology, Cascaden Ridge, All tags... Copper, Eolian, Fossils, Geochemistry, Geochronology, Geologic Map, Gold, Igneous Rocks, Livengood, Livengood Bench, Livengood Quadrangle, Man-Made Deposits, Metamorphic Rocks, Money Knob, Plutonic Rocks, Ranney Hollow, STATEMAP Project, Sedimentary Rocks, Shorty Creek, Silver, Surficial Geology, Tailings, Tolovana Mining District, Tolovana River, 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 Geochemistry of some quaternary lavas from the Aleutian Arc and Mt. Wrangell This publication contains previously unpublished geochemical analyses or re-analyses of lavas, magmatic inclusions, and a few gabbroic cumulate inclusions from Alaska volcanoes (Akutan, Augustine, Buzzard Creek, Dana, Douglas, Fourpeaked, Frosty, Great Sitkin, Iliamna, Kaguyak, Kiska, Okmok, Prindle Cone, Recheshnoi, Redoubt, Spurr, Ukinrek Maars, Vsevidof, Westdahl, Wrangell) collected by the authors and others over the past 35 years. It provides substantial data sets for three volcanoes (Vsevidof, Westdahl, and Douglas) for which little or no published data exist. All analyses were made by the GeoAnalytical laboratory at Washington State University in Pullman, WA. The ICP/MS data have been reduced using the 2006... Tags: Adagdak, Adak, Akutan, Analyses, Analyses and Sampling, All tags... Analytical Lab Results, Analytical Results, Augustine, Augustine Volcano, Basalt, Bedrock, Bogoslof, Chemistry, Colorado Creek, Crater Peak, Crystals, Douglas, Faris Peak, Fourpeaked, Frosty, Frosty Peak, Geochemical Data, Geochemistry, Geochronology, Geologic, Geology, Glacier Creek, Hayes, Hazards, Ice, Iliamna, Iliamna Volcano, Jag Peak, Juneau, Kaguyak, Kansas Creek, Kasatochi, Katmai, Kiska, Maars, Mount Douglas, Mount Peulik, Mount Recheshnoi, Mount Spurr, Mount Wrangell, Mount Zanetti, Nikolski, Okmok, Okmok Caldera, Pavlof, Prindle Volcano, Redoubt, Redoubt Volcano, Rhyolite, Rocks, Sample Location, Spurr, Tanana, Tephra, The Sisters, Ukinrek, Ukinrek Maars, Uliaga, Umnak Island, Unimak, Volcanic, Volcanic Arc, Volcanic Rocks, Volcanoes, Volcanology, Vsevidof, Westdahl, Whittier, Wrangell, Yakutat, 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 Geologic map of the Talkeetna Mountains C-4 Quadrangle and adjoining areas, central Alaska The Alaska Division of Geological & Geophysical Surveys (DGGS), in partnership with the U.S. National Cooperative Geologic Mapping Program, mapped approximately 450 mi2 of the Talkeetna Mountains region of central Alaska at 1:50,000 scale over the course of six weeks in 2014. This area contains significant exposures of Late Triassic mafic volcanics and gabbro sills that have been the focus of region-wide exploration for the Strategic and Critical platinum-group elements (PGEs). The area also exposes numerous inactive and possibly active faults which project through the area of proposed hydropower development. The resulting geologic map offers an improved understanding of the geology, structural history, and mineral... Tags: 40Ar/39Ar, Aerial Geology, Aerial Photography, Alluvial, Alluvial Deposits, All tags... Amphibolite Facies Units, Bedrock Geologic Map, Bedrock Geology, Brachiopods, Cleary Creek, Colluvial Deposits, Cordilleran Ice Sheet, Crinoids, Esker, Faulting, Faults, Floodplain, Fluvial, Fossils, Geochronology, Geologic Map, Geologic Materials, Geomorphology, Glacial, Glacial Deposits, Glacial Drift, Glacial Geology, Glacial Geomorphology, Glacial History, Glacial Lake, Glacial Processes, Glacial Stratigraphy, Glaciation, Ice Contact Deposits, Ice-Contact, Iron Creek, Lacustrine, Lacustrine Sedimentation, Landslide, Landslide Deposit, Outwash, Outwash Fan, Paleochannel, Permafrost and Periglacial, Remote Sensing, Rock Glaciers, Rock-Glacier Deposits, Rockfall, STATEMAP Project, Sand and Gravel, Slides, Slope Instability, Soil Creep, Stephan Lake, Surficial, Surficial Geologic Map, Surficial Geology, Talkeetna Mountains, Talkeetna Mountains Quadrangle, Talkeetna River, Till, geoscientificInformation, Fewer tags Geologic map of portions of the Livengood B-3, B-4, C-3, and C-4 quadrangles, Tolovana mining district, Alaska This geologic map and report depicts portions of the Livengood B-3, B-4, C-3, and C-4 quadrangles. The Livengood area is a historically productive placer mining area approximately 80 road miles north of Fairbanks, Alaska. This report synthesizes recently collected and previously published agency and industry geologic data in a 1:50,000-scale comprehensive geologic map to build a better understanding of the geology and mineral-resource potential of the Livengood area. It expands and updates the Alaska Division of Geological & Geophysical Surveys (DGGS) Preliminary Interpretive Report (PIR) 2004-3 with the addition of new DGGS mapping and drillhole data from ITH, and integrates previously published DGGS surficial... Tags: 40Ar/39Ar, Airborne Geophysical/Geological Mineral Inventory, Bedrock, Bedrock Geology, Cascaden Ridge, All tags... Copper, Eolian, Fossils, Geochemistry, Geochronology, Geologic Map, Gold, Igneous Rocks, Livengood, Livengood Bench, Livengood Quadrangle, Man-Made Deposits, Metamorphic Rocks, Money Knob, Plutonic Rocks, Ranney Hollow, STATEMAP Project, Sedimentary Rocks, Shorty Creek, Silver, Surficial Geology, Tailings, Tolovana Mining District, Tolovana River, geoscientificInformation, Fewer tags Surficial geologic map of the Shaktoolik area, Norton Bay Quadrangle, Alaska This 1:50,000 scale geologic map describes the distribution of unconsolidated deposits, identifies local geologic hazards, and provides information about the depositional environment and basic engineering properties of common surficial-geologic materials in and around Shaktoolik, Alaska. Map units are the result of combined field observations and aerial imagery interpretation. A suite of local ground observations were collected over a two-week period in July 2011 by a helicopter-supported team of DGGS geologists and collaborators. Field investigations included soil test pits, sample collection, soil and rock description, oblique aerial photography, and documentation of landscape morphology. Tags: Alluvial, Alluvium, Analyses and Sampling, C14, Clay, All tags... Coastal, Coastal and River, Colluvium, Conglomerate, Construction Materials, Engineering, Engineering Geology, Eolian, Erosion, Fan, Flood, Floodplain, Fluvial, Gelifluction, Geochronology, Geologic, Geologic Hazards, Geologic Map, Geology, Geomorphology, Geotechnical, Gravel, Hazards, Ice, Image Interpretation, Interpretation, Inundation, Lacustrine, Lakes, Meltwater, Norton Bay Quadrangle, Permafrost, Permafrost and Periglacial, Resource Assessment, Resources, Rocks, Sand, Sand and Gravel, Sediment, Sedimentation, Shaktoolik, Silt, Slope, Slump, Surface, Surficial, Surficial Geologic Map, Surficial Geology, Terrace, Thaw Lakes, Thawing Permafrost, Thermokarst, geoscientificInformation, Fewer tags 40AR/39AR Ages from the East Bonnifield geologic map area, Fairbanks A-1, Fairbanks A-2, Healy D-1, and Healy D-2 quadrangles, Alaska 40Ar/39Ar data from plutonic, dike, and alteration samples collected during geologic mapping of the eastern part of the Bonnifield mining district geologic map area in parts of Fairbanks A-1 and Fairbanks A-2 and Healy D-1 and Healy D-2 quadrangles yield results indicating the plutons, dikes, and a gold-bearing quartz vein in the Bonnifield Map area range from 85 to 95 m.y. Tags: 40Ar/39Ar, Age Dates, Alaska Range, Alaska, State of, Buzby prospect, All tags... Chute Creek, Denali Borough, Dry Creek, Dry Creek placer mine, Dry Creek prospect, Fairbanks Quadrangle, Forgotten Creek, Geochronology, Geology, Glacier Creek, Glory Creek, Glory Creek prospect, Healy Quadrangle, Kansas Creek, Kansas Creek prospect, LEA Creek prospect, Newman Creek, Newman Creek placer mine, Red Mountain Creek, Red Mountain Creek prospect, Rogers Creek, STATEMAP Project, Sheep Creek, Slate Creek, Slide Creek, Smog prospect, Snow Mountain Gulch, Threemile Creek, WTF (Western Tundra Flats) prospect, West Fork Little Delta River, Wood River, 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 40Ar/39Ar data, Seward Peninsula, Alaska This Alaska Division of Geological & Geophysical Surveys (DGGS) Raw Data File presents 40Ar/39Ar age dating results for a volcanic whole-rock sample, selected minerals from various metamorphic rocks and igneous dikes, and white mica from both metamorphic- and hydrothermal-mineralization-related veins encountered on the southern Seward Peninsula, as well as select minerals from one plutonic rock from Cape Denbeigh, eastern Norton Sound, Alaska. Cooling ages on glaucophane, barroisite, amphibole, paragonite, and biotite from metamorphic rocks range from 84 Ma to 209 Ma. The cooling age of white mica in a possible fault zone is 144 Ma. Cooling ages on late-stage metamorphic minerals (winchite and white mica) from veins... Tags: 40Ar/39Ar, Age Dates, Ar-Ar, Bendeleben Mountains, Bendeleben Quadrangle, All tags... Big Hurrah Mine, Bluff (Place), Cape Denbeigh, Council, Council Mining District, Geochronology, Koyuk Mining District, Mineral Resources, Nome, Nome Mining District, Nome Quadrangle, Norton Bay Quadrangle, Norton Sound, STATEMAP Project, Seward Peninsula, Solomon Quadrangle, geoscientificInformation, Fewer tags 40Ar/39Ar data from the Talkeetna Mountains C-4 Quadrangle and adjoining areas, central Alaska This report presents 40Ar/39Ar step-heating geochronology results for igneous and metamorphic rocks from the Alaska Division of Geological & Geophysical Surveys' (DGGS) Talkeetna Mountains C-4 Quadrangle and Adjoining Areas geologic mapping project. Hornblende-bearing gabbro returned a Late Triassic crystallization age consistent with regional results for Nikolai Greenstone-related magmatism. We determined Early Jurassic metamorphic ages for hornblende and sericite from two samples of upper greenschist to amphibolite grade metavolcanic rocks. Our results indicate that a granodiorite pluton intruding Wrangellia in the study area has a Middle Jurassic age consistent with the Talkeetna Arc, indicating that the Wrangellia... Tags: 40Ar/39Ar, Age Dates, Analyses, Analyses and Sampling, Analytical Lab Results, All tags... Analytical Results, Ar-Ar, Bedrock, Bedrock Geology, Geochronology, Geology, Lab Methods, Plutonic Rocks, Plutons, STATEMAP Project, Sample Location, Strategic and Critical Minerals Assessment Project, Talkeetna Mountains Quadrangle, Volcanic, Volcanic Arc, Volcanic Rocks, 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 Geologic map of Mount Chiginagak volcano, Alaska Mount Chiginagak is a hydrothermally active volcano on the Alaska Peninsula, approximately 170 km south-southwest of King Salmon, Alaska. This small stratovolcano, approximately 8 km in diameter, has erupted through Tertiary to Permian sedimentary and igneous rocks. The eruptive products of Chiginagak volcano record a history of chiefly andesite lava flows and associated block-and-ash flows. The oldest lavas exposed are Pleistocene in age and are found everywhere around the edifice except in the northeast sector, where Holocene lava flows dominate the landscape. Holocene activity has covered the northeast flank with rubbly-topped andesite lava flows that extend as far as 4.6 km from their source vent at the summit... Tags: Alaska Peninsula, Aleutian Range, Analyses, Chiginagak, Gas, All tags... Geochemistry, Geochronology, Geologic, Geology, Hazards, Igneous, Lahar, Mount Chiginagak, Neoglacial, Pumice, Rocks, Sediment, Sulfur, Surface, Surficial, Tephra, Ugashik Quadrangle, Volcanic, Volcanic Ash, Volcanic Eruption, Volcanic Gas, Volcanic Rocks, Volcaniclastic Deposits, Volcaniclastics, Volcanoes, Volcanology, Water, geoscientificInformation, Fewer tags 1 2 »