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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...
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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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Cook Inlet has been recognized as the second-largest petroleum province in Alaska, second only to the North Slope. The south-central Tyonek Quadrangle is an area of significant geologic interest because it is the only location in Cook Inlet where the entire producing stratigraphy of the basin is exposed on the surface. Additionally, this area encompasses the structural boundary between the forearc basin and its sediment source rocks. To better understand the petroleum system and the geologic relationships between the exhumed arc intrusive rocks and adjacent Cenozoic stratigraphy of the Cook Inlet forearc basin, during the summer of 2010 the Alaska Division of Geological & Geophysical Surveys conducted a federally-funded...
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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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Geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) and the University of Alaska Fairbanks (UAF) carried out geologic field surveys, including bedrock mapping and sampling, in the Alaska Highway Corridor from 2006 through 2010. The fieldwork provides basic information critical to building an understanding of Alaska's geology and is part of a broader, integrated program that includes airborne geophysical surveys, bedrock and surficial mapping, a mineral-resource assessment, a geologic-hazards assessment, and other geological studies. This publication contains descriptive, location, and analytical information for samples collected in the Mount Hayes, Tanacross, and Nabesna quadrangles, Alaska,...
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This digital map database, compiled from previously published andunpublished data, and new mapping by the authors, represents thegeneral distribution of bedrock and surficial deposits in the mapped area.Together with the accompanying text file (skmf.txt, skmf.pdf, orskmf.ps), it provides current information on the geologic structure andstratigraphy of the area covered. The database delineates map units thatare identified by general age and lithology following the stratigraphicnomenclature of the U.S. Geological Survey. The scale of the source mapslimits the spatial resolution (scale) of the database to 1:24,000 orsmaller.
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This digital map database, compiled from previously published andunpublished data, and new mapping by the authors, represents thegeneral distribution of bedrock and surficial deposits in the mappedarea. Together with the accompanying text file (pamf.ps, pamf.pdf,pamf.txt), it provides current information on the geologic structureand stratigraphy of the area covered. The database delineates mapunits that are identified by general age and lithology following thestratigraphic nomenclature of the U.S. Geological Survey. The scaleof the source maps limits the spatial resolution (scale) of thedatabase to 1:62,500 or smaller.
Tags: 06081 = San Mateo, 06085 = Santa Clara, 06087 = Santa Cruz, 1100 - Geology, 1101 - General, All tags...
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Bedrock geology strongly influences area soil and water chemistry. Even in glaciated landscapes, studies suggest that soil parent material is commonly of local origin, rarely being ice-transported more that a few miles from its source. Bedrock types also differ in how they weather and in the physical characteristics of the residual soil type. Because of this, local lithology is usually the principle determinant of soil chemistry, texture, and nutrient availability. Many ecological community types are closely related to the chemistry and drainage of the soils or are associated with particular bedrock exposures. We grouped bedrock units on the bedrock geology maps of ME, NH, VT, MA, CT, RI, NY, PA, NJ, and MD into...
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Fault features within the Bill, Wyoming 30' x 60' quadrangle. It is a digitized version of bedrock geology map series developed by the Wyoming Geological Survey. The information provides basic bedrock geologic information and features to include named and geologic map units based on the rock types present. It is a STATEMAP product. This dataset is available for purchase through the WSGS, Digital Product MS-72, http://sales.wsgs.uwyo.edu/catalog/advanced_search_result.php?keywords=MS-72
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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...
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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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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.
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This digital map database, compiled from previously publishedand unpublished data, and new mapping by the authors,represents the general distribution of bedrock and surficialdeposits in the mapped area. Together with the accompanyingtext file (nesfmf.ps, nesfmf.pdf, nesfmf.txt), it providescurrent information on the geologic structure and stratigraphyof the area covered. The database delineates map units thatare identified by general age and lithology following thestratigraphic nomenclature of the U.S. Geological Survey. Thescale of the source maps limits the spatial resolution (scale)of the database to 1:62,500 or smaller.
Tags: 06013 = Contra Costa, 06041 = Marin, 06055 = Napa, 06067 = Sacramento, 06077 = San Joaquin, All tags...
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This digital map database, compiled from previously published andunpublished data, and new mapping by the authors, represents thegeneral distribution of bedrock and surficial deposits in themapped area. Together with the accompanying text file (ceghmf.ps,ceghmf.pdf, ceghmf.txt), it provides current information on thegeologic structure and stratigraphy of the area covered. Thedatabase delineates map units that are identified by general ageand lithology following the stratigraphic nomenclature of the U.S.Geological Survey. The scale of the source maps limits the spatialresolution (scale) of the database to 1:100,000 or smaller.
Tags: 06023 = Humboldt, 06045 = Mendocino, 06103 = Tehama, 06105 = Trinity, Bear River fault zone, All tags...
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This digital map database, compiled from previously publishedand unpublished data, and new mapping by the authors,represents the general distribution of bedrock and surficialdeposits in the mapped area. Together with the accompanyingtext file (scvmf.ps, scvmf.pdf, scvmf.txt), it provides currentinformation on the geologic structure and stratigraphy of thearea covered. The database delineates map units that areidentified by general age and lithology following thestratigraphic nomenclature of the U.S. Geological Survey. Thescale of the source maps limits the spatial resolution (scale)of the database to 1:24,000 or smaller.
Tags: 06085 = Santa Clara, 06087 = Santa Cruz, Aldercroft fault, Ben Lomond fault block, Berrocal fault, All tags...
This collection is comprised of legacy DGGS geologic maps that have been converted to the single-map USGS Geologic Map Schema (GeMS; formerly known as NCGMP09). Initial conversions will be conducted on maps in areas with critical mineral potential, benefiting DGGS and USGS critical mineral studies in Alaska. Future additions to this collection will include both converted geologic maps, and new geologic maps created using the GeMS schema.
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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...
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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,...
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Digital file containing a bedrock geology polygon coverage for British Columbia. Polygon coverage of geology compiled at 1:100,000 scale as part of the B.C. Ministry of Energy and Mines, BC Geological Survey Branch mineral potential project, 1994-1996. Original coding revised and rationalized in 2001-2002 by D.G. MacIntyre, updated and revised in 2002-2004 by N.W.D. Massey. Coverage generalized on lithostratigraphic map unit (MAPLABEL) designation. New mapping completed after 1996 is being added to this file on an ongoing basis. Bedrock Geology - This theme consists of a single layer of bedrock geology polygons. Polygons depict the nature of the bedrock geology based on a compilation of all geologic mapping done...


map background search result map search result map Faults of the Bill 30' x 60' Quadrangle at 1:100,000 Bedrock Geolog Geologic map and map database of the Palo Alto 30' X 60' quadrangle, California Geologic map of the Cape Mendocino, Eureka, Garberville,and southwestern part of the Hayfork 30 X 60 Quadrangles and Adjacent OffshoreArea, Northern California Geologic map and map database of the Spreckels 7.5-minutequadrangle, Monterey County, California Geologic maps and structure sections of the southwestern SantaClara Valley and southern Santa Cruz Mountains, Santa Clara andSanta Cruz Counties, California Geologic map and map database of northeastern San Francisco Bay region, California; Most of Solano County and parts of Napa, Marin, Contra Costa, San Joaquin, Sacramento, Yolo, and Sonoma Counties Bedrock Geology, Northern Appalachians/Acadians Geology of Kasatochi volcano, Aleutian Islands, Alaska Major-oxide, minor-oxide, and trace-element geochemical data from rocks collected in the Alaska Highway corridor, Mount Hayes, Tanacross, and Nabesna quadrangles, Alaska, in 2006, 2008, 2009, and 2010 Zircon U-Pb age data, Alaska Highway Corridor, Tanacross and Nabesna quadrangles, Alaska 40Ar/39Ar data, Ray Mountains area, Bettles Quadrangle, Alaska 40Ar/39Ar data, Styx River map area, Lime Hills C-1 Quadrangle, Alaska Major-oxide and trace-element geochemical data from rocks collected in 2010 in the Tyonek Quadrangle, Alaska U-Pb zircon age data from meta-igneous rocks in the Clearwater Mountains, Mount Hayes A-6 Quadrangle, Alaska 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 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 Geologic map of portions of the Livengood B-3, B-4, C-3, and C-4 quadrangles, Tolovana mining district, Alaska Collection of digital geologic maps from Alaska Zircon U-Pb and 40Ar/39Ar results from dikes collected within the Bruin Bay fault zone, lower Cook Inlet Geology of Kasatochi volcano, Aleutian Islands, Alaska 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 Geologic map and map database of the Spreckels 7.5-minutequadrangle, Monterey County, California 40Ar/39Ar data, Styx River map area, Lime Hills C-1 Quadrangle, Alaska Geologic maps and structure sections of the southwestern SantaClara Valley and southern Santa Cruz Mountains, Santa Clara andSanta Cruz Counties, California Faults of the Bill 30' x 60' Quadrangle at 1:100,000 40Ar/39Ar data, Ray Mountains area, Bettles Quadrangle, Alaska Major-oxide and trace-element geochemical data from rocks collected in 2010 in the Tyonek Quadrangle, Alaska Geologic map and map database of the Palo Alto 30' X 60' quadrangle, California Geologic map and map database of northeastern San Francisco Bay region, California; Most of Solano County and parts of Napa, Marin, Contra Costa, San Joaquin, Sacramento, Yolo, and Sonoma Counties 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 Zircon U-Pb age data, Alaska Highway Corridor, Tanacross and Nabesna quadrangles, Alaska Geologic map of the Cape Mendocino, Eureka, Garberville,and southwestern part of the Hayfork 30 X 60 Quadrangles and Adjacent OffshoreArea, Northern California Major-oxide, minor-oxide, and trace-element geochemical data from rocks collected in the Alaska Highway corridor, Mount Hayes, Tanacross, and Nabesna quadrangles, Alaska, in 2006, 2008, 2009, and 2010 Collection of digital geologic maps from Alaska Bedrock Geolog Bedrock Geology, Northern Appalachians/Acadians