Filters: Tags: igneous rocks (X)
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View north toward basalt dike (photograph EI10) in Hakatai Shale, Unkar Group, on north side of river mile 77.2, at beginning of Hance Rapids. Shinumo Sandstone forms cliff at upper edge of photograph.
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...
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...
Mineral Resources Section personnel from the Alaska Division of Geological & Geophysical Surveys (DGGS) carried out a geologic 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 geologic mapping. Specifically, this work provides geologic context for geophysical surveys conducted in 2006. Interpretation and synthesis of this data has been presented in professional and trade meetings....
Aerial view north towards Vulcans Throne volcano in distance on north side of river mile 179.3. View in foreground is north along Toroweap Fault in lower Prospect Canyon at faulted unnamed Pleistocene cinder cone and alluvium on east side of Prospect Canyon. Mount Trumbull (Pliocene basalt) on skyline, left side of photograph.
Aerial view north toward 900-foot-thick Cardenas Basalt of Unkar Group (black), that overlies Ochoa Point Member of Dox Formation, Unkar Group (red slope), overlain by Nankoweap Formation (purple strata), west side of Ochoa Point, 1 mile northwest of river mile 71.0.
Views northwest toward white Miocene tuff beds in the Gyp Hills, 2 miles east of Tassi Spring, north side of Tassi Wash.
Aerial view north toward 18-million-year (Ma) Peach Spring Tuff (brown) that overlies white Tertiary West Water Formation in upper Milkweed Canyon.
View of the west-facing wall inside 1,000-year-old Little Spring volcano, 2 miles south of Mount Trumbull.
Hundred and Fiftynine Mile Dike at top of Redwall Limestone (person for scale on dike), south of river mile 159.7.
View north toward basalt cascade down north wall of river, river mile 181.4.
View northwest and downriver toward basalt cascades over Esplanade Sandstone at north rim, Redwall Limestone (large gray cliff), undifferentiated Devonian and Cambrian strata below Redwall Limestone cliff to river, from river mile 184.3.
Aerial view north toward south side of Quaternary basalt neck and pyroclastic deposits of Yumtheska Vent West sample site, K-Ar age 0.780±0.15 thousand years (ka) (Wenrich and others, 1995).
Aerial view northwest toward basalt dikes (photograph EI06) on west side of Unkar Creek canyon in Solomon Temple Member of Dox Formation, Unkar Group, about 2 miles west of river mile 72.5.
This U.S. Geological Survey (USGS) data release provides whole rock major, minor, and trace element geochemical data from the fluorine-rich Mount Emmons-Redwell porphyry molybdenum (Climax-type) deposit (Mt. Emmons-Redwell deposit), located approximately 5.6 km (3.5 mi) northwest of Crested Butte, Colorado. The Mt. Emmons-Redwell deposit partly underlies Redwell Basin on the northwest flank of Mount Emmons in the west-central region of the Colorado Mineral Belt. Mineralization of the Mt. Emmons-Redwell deposit occurs at depth as vein, veinlet, stockwork, and fracture-hosted Climax-type mineralization [308 Mt at 0.32% Mo (Galey, 1978; Guarnera and Anderson, 2007)], and is associated with the Mt. Emmons igneous complex....
Categories: Data;
Types: Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: <1GB,
Climax-type deposit,
Colorado,
Colorado Mineral Belt,
Crested Butte,
This dataset is intended to provide seamless, integrated geologic mapping of the U.S. Intermountain West region as a contribution to The National Geologic Map supported by the National Cooperative Geologic Mapping Program of the U.S. Geological Survey. Surficial and bedrock geology are included in this data release as independent datasets at a variable resolution from 1:50,000 to 1:250,000 scale. No original interpretations are presented in this dataset; rather, all interpretive data are assimilated from referenceable publications. Derivative polygon features created for this dataset demonstrate the distribution of SIGMa-GeMS Geologic Provinces derived from the distribution of map units. Initial contributions to...
The Reef Package is a sequence of coarse-grained cumulates that host the J-M Reef Pd-Pt deposit in the Stillwater Complex of Montana. The top of the Reef Package marks the top of economic-grade platinum-group element mineralization and is identified by a distinct change in rock fabric, from the coarse-grained rocks of the Reef Package to finer-grained cumulates in the hanging wall. This dataset tabulates whole-rock major, minor, and trace element geochemistry of rock samples collected from diamond drill holes that intersect the textural discontinuity at the top of the Reef Package from the underground working of the Stillwater Mine. The dataset also tabulates rock fabric data collected by electron backscatter diffraction...
Categories: Data;
Tags: Economic Geology,
Geochemistry,
Mineral Resources,
Montana,
USGS Science Data Catalog (SDC),
A mineral resource assessment was performed by the U.S. Geological Survey (USGS) to assess the potential of undiscovered skarn-hosted tungsten resources in the Northern Rocky Mountain region of eastern Idaho and western Montana. This region has seen moderate tungsten trioxide (WO3) production in the past from a variety of mineralization styles including skarn, vein and replacement, and wolframite-quartz veins. The geology of the area is dominated by large plutons of Cretaceous to Tertiary age, emplaced into a belt of sedimentary rock ranging from Mesoproterozoic to Permian age, and affected by tectonism related to the Sevier and later Laramide orogenies. Known tungsten (W) skarn mineral sites are associated with...
Categories: Data;
Types: ArcGIS REST Map Service,
ArcGIS Service Definition,
Downloadable,
Map Service;
Tags: Ashton,
Bald Mountain,
Beaverhead County,
Bitterroot Range,
Boise County,
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.
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