Filters: Tags: Metamorphic Rocks (X)
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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...
Black river-polished amphibolitic schist, west (left) bank of river mile 127.5.
Aerial view northwest toward Horn Creek Rapids, river mile 90.9, showing numerous pegmatite and granite dikes in black Vishnu Schist. Inner canyon is 1,300 feet deep here.
Aerial view south and downriver from river mile 211.9 toward a Precambrian “island” of schist (photographs WM07, WM08, WM09) during the basal Cambrian sea encroachment, right bank of river mile 212.5.
View west toward granite rocks (photograph WM01) on west side of river mile 190.1 from Hundred and Ninety Mile canyon.
View southwest and downriver toward Vishnu Schist below Tapeats Sandstone, river mile 112.6.
The geology of an area of 660 square miles mostly in the northeastern corner of Tennessee and small adjacent areas in Virginia and North Carolina is the subject of this report. The region lies principally in the Unaka province, with extensions northwestward into the Appalachian Valley and southwestward into the Blue Ridge province. The report combines results of surveys made between 1941 and 1953 by the U. S. Geological Survey, the Tennessee Division of Geology, and the Tennessee Valley Authority, and is published in cooperation with the Tennessee Division of Geology. Northeasternmost Tennessee is a region of widespread mineralization and was formerly important for mineral production. Iron, manganese, and bauxite...
The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States (https://doi.org/10.5066/F7WH2N65) represents a seamless, spatial database of 48 State geologic maps that range from 1:50,000 to 1:1,000,000 scale. A national digital geologic map database is essential in interpreting other datasets that support numerous types of national-scale studies and assessments, such as those that provide geochemistry, remote sensing, or geophysical data. The SGMC is a compilation of the individual U.S. Geological Survey releases of the Preliminary Integrated Geologic Map Databases for the United States. The SGMC geodatabase also contains updated data for seven States and seven entirely new State geologic...
Categories: Data,
Data Release - Revised;
Types: ArcGIS REST Map Service,
ArcGIS Service Definition,
Downloadable,
Map Service;
Tags: Alabama,
Arizona,
Arkansas,
California,
Colorado,
River-polished Vishnu Schist, north bank of Crystal Rapids, river mile 98.7.
View northwest toward southeast side of Precambrian Zoroaster Granite “island” of Cambrian seaway, onlapped by Cambrian Tapeats Sandstone, from Tonto Trail, south of river mile 85.1.
The Preliminary Interpretive Report 2004-3B, "Bedrock geologic map of the Livengood SW C-3 and SE C-4 quadrangles, Tolovana mining district, Alaska," is the bedrock geologic map of an approximately 123-square-mile area in the central Livengood Quadrangle, Alaska.
Fortymile mining district electromagnetic and magnetic airborne geophysical survey, data compilation
The Fortymile electromagnetic and magnetic airborne geophysical survey data were acquired with a DIGHEM-V Electromagnetic (EM) system and a cesium magnetometer. The EM and magnetic sensors were flown at a height of 30 meters (m). In addition the survey recorded data from radar and laser altimeters, a GPS navigation system, 50/60 Hz monitors and a video camera. Flights were performed with an AS-350-B2 Squirrel helicopter at a mean terrain clearance of 60 m along N-S survey flight lines with a spacing of 400 m. Tie lines were flown perpendicular to the flight lines at intervals of approximately 4,800 m
View southeast and downriver toward metamorphic rocks with granitic dikes, north of Granite Park, river mile 208.2.
Pegmatite dikes in schist, south bank of river mile 80.5.
Overview This directory was developed to provide discovery information for anyone looking for publicly accessible repositories that house geological materials in the U.S. and Canada. In addition, this resource is intended to be a tool to facilitate a community of practice. The need for the directory was identified during planning for and follow-up from a drill core repository webinar series in Spring 2020 for public repository curators and staff in the U.S. and Canada hosted by the Minnesota Geological Survey and the Minnesota Department of Natural Resources. Additional supporting sponsors included the U.S. Geological Survey National Geological and Geophysical Data Preservation Program and the Association of American...
Categories: Data;
Types: Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Alabama,
Alaska,
Alberta,
Arkansas,
British Columbia,
This data set contains boundaries and tags for major geologic units in Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands. In addition to the polygons representing the areal extent of geologic units, it identifies major faults and continental glaciation in Alaska. The data depict the geology of the bedrock that lies at or near the land surface, but not the distribution of surficial materials such as soils, alluvium, and glacial deposits. This map complements the Generalized Geologic Map of the Conterminous United States by Reed and Bush. The data are generalized from a compilation prepared for use in the Geologic Map of North America, published as a paper map by the Geological Society of America and...
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: AK,
Alaska,
Bedrock,
Faults,
Geologic History,
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.
Re-analyses of sample pulps and bulk rejects from historic USBM rock and heavy-mineral-concentrate samples were conducted by the Alaska Division of Geological & Geophysical Surveys (DGGS) as part of the State of Alaska's Strategic and Critical Minerals Assessment project, which is designed to evaluate Alaska's potential for these resources. The objective of this resource assessment is to expand the state's geochemical database by obtaining and publishing modern, quantitative geochemical analyses for historic USBM samples, where available. Highlights of this re-analysis project include heavy mineral concentrates with up 7,220 ppm Sn, 5,870 ppm Cr, and 17,000 ppm Mn.
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.
Aerial view north into Clear Creek canyon, about 1 mile north of river mile 84.7. View of vertical beds of Paleoproterozoic Vishnu Schist overlain by horizontal Cambrian Tapeats Sandstone (brown cliff) in foreground, and tilted Mesoproterozoic Bass Formation in distance, that marks the Great Unconformity.
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