Isotopic analysis

Experimental determination of the proportion of a given isotope (or isotopes) in a sample.
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Results listed by similarity [list alphabetically]
A geochemical isotopic (Nd-Pb) comparison of volcanic rocks erupted during the last 3,550 yrs. B.P. of interplinian activity of Somma-Vesuvius Volcano, southern Italy

Nd and Pb isotopic analyses from stratigraphic sampling from Somma-Vesuvius volcanic complex, Italy, during the last 3550 years point to contributions from heterogeneous lithosphere, continental crust, and magma mixing.

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Geochemical and stable isotopic data on barren and mineralized drill core in the Devonian Popovich Formation, Screamer sector of the Betze-Post gold deposit, northern Carlin trend, Nevada

Detailed chemical and isotopic analysis of host and associated rocks within an area that is currently the largest producer of gold in the US. Part of a study of the hydrothermal activity leading to the formation of these gold deposits.

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Geochemical and Sulfur-Isotopic Signatures of Volcanogenic Massive Sulfide Deposits on Prince of Wales Island and Vicinity, Southeastern Alaska

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Isotopic ages of rocks in the northern Front Range, Colorado

Maps, tables, and GIS data for isotopic ages determined in the northern part of the study area.

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Mesozoic magmatism and base-metal mineralization in the Fortymile mining district, eastern Alaska--Initial results of petrographic, geochemical, and isotopic studies in the Mount Veta area

Initial results of a petrographic, geochemical, and isotopic study of Mesozoic intrusive rocks and spatially associated Zn-Pb-Ag-Cu-Au prospects in the area.

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Synthesis of petrographic, geochemical, and isotopic data for the Boulder batholith, southwest Montana

Geochemical and mineralogical analyses of plutonic rock samples

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A compilation of K-Ar-ages for southern California

Conventional K-Ar ages for granitic, volcanic, and metamorphic rocks collected in this area.

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Geochemical data from groundwater at the proposed Dewey Burdock uranium in-situ recovery mine, Edgemont, South Dakota

Groundwater geochemistry data from samples that were collected in June 2011 to better understand the hydrogeologic system in the area surrounding the proposed mine site.

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Geochemical database for igneous rocks of the ancestral Cascades Arc--southern segment, California and Nevada

Compilation of all available chemical data (more than 2,000 samples) for igneous rocks that constitute the southern segment of the ancestral Cascades magmatic arc.

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Geochemical, modal, and geochronologic data for 1.4 Ga A-type granitoid intrusions of the conterminous United States

This report presents and makes data available to ongoing petrogenetic investigations of these rocks. It develops an accurate and current portrayal of their spatial distribution in GIS format while analyzed samples are presented via Excel workbooks.

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Geochemistry, geochronology, mineralogy, and geology suggest sources of and controls on mineral systems in the southern Toquima Range, Nye County, Nevada

Geochemical analysis of rock samples in DBF tables from the PLUTO database. Maps are provided in PDF only.

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Geochronology and correlation of Tertiary volcanic and intrusive rocks in part of the southern Toquima Range, Nye County, Nevada

40Ar/39Ar dating, electron microprobe analyses and geologic mapping help clarify chronology and correlations of the numerous volcanic and intrusive units exposed in the area and interpret the petrogenesis of a few of the volcanic units.

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Geochronology and geology of late Oligocene through Miocene volcanism and mineralization in the western San Juan mountains, Colorado

New age determinations with descriptions of sample locations and analytical details.

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Geochronology Database for Central Colorado

Compilation of isotopic and fission track age determinations, some previously published. Data for the tephrochronology of Pleistocene volcanic ash, carbon-14, Pb-alpha, common-lead, and U-Pb determinations on uranium ore minerals are not included.

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Geochronology of Cenozoic rocks in the Bodie Hills, California and Nevada

Presents data for mineral deposits and unaltered and hydrothermally altered volcanic rocks. Data presented were acquired in three USGS labs by three different geochronologists. Analytical methods and data derived from each lab are presented separately.

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Geologic and geophysical maps of the eastern three-fourths of the Cambria 30 x 60 degree quadrangle, central California Coast Ranges

Contains geologic, gravity anomaly, and aeromagnetic anomaly maps and the associated geologic and geophysical databases (ArcMap), as well as complete descriptions of the geologic map units and the structural relations in the mapped area.

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Geologic map of Alaska

Digital compilation and reinterpretation of published and unpublished geologic mapping of Alaska.

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Geologic map of Alaska

Digital compilation and reinterpretation of published and unpublished geologic mapping of Alaska.

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Geologic map of the Big Delta B-1 quadrangle, east-central Alaska

Geologic mapping and U-Pb age dating of the Big Delta B-1 quadrangle provides insights into the geology and gold mineralization of the headwater region of the Goodpaster River.

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Geologic map of the Big Delta B-2 quadrangle, east-central Alaska

Geologic map of the Big Delta B-2 quadrangle, including U-Pb geochronology, correlation chart, and description of map units.

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Geologic map of the Bodie Hills, California and Nevada

Spatial geologic map with rock type, vents, arcs, landslides, etc. provided in an ESRI geodatabase and KMZ format for Google Earth viewing. Mapsheet with accompanying descriptive pamphlet is provided as a PDF. Petrographic rock summary is also included.

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Geologic map of the Cook Inlet region, Alaska, including parts of the Talkeetna, Talkeetna Mountains, Tyonek, Anchorage, Lake Clark, Kenai, Seward, Iliamna, Seldovia, Mount Katmai, and Afognak 1:250,000-scale quadrangles

The map updates a major geologic map of the Cook Inlet region published in 1976 incorporating new and additional mapping and interpretation. This map is also a revision of areas of overlap with the geologic map completed for central Alaska.

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Geologic map of the east half of the Lime Hills 1:250,000-scale quadrangle, Alaska

This map, compiled from geologic mapping conducted (1985-1992) by the U.S. Geological Survey as part of the Alaska Mineral Resource Assessment Program, builds upon previous USGS work unraveling the magmatic history of the Alaska-Aleutian Range batholith.

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Geologic map of the Kechumstuk fault zone in the Mount Veta area, Fortymile mining district, east-central Alaska

This map depicts the fundamental geologic features for the western part of the Fortymile mining district and delineates the location of known bedrock mineral prospects and their relationship to rock types and structural features.

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Geology of the Prince William Sound and Kenai Peninsula region, Alaska

The region includes a significant part of one of the world’s largest accretionary complexes and a small part of the classic magmatic arc geology of the Alaska Peninsula. The map was compiled from existing mapping augmented by available new or revised data

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Geology, geochemistry, and genesis of the Greens Creek massive sulfide deposit, Admiralty Island, southeastern Alaska

This metal ore deposit formed over a period of time in which its tectonic setting was changing, consequently it shows a range of characteristics typical of several different types of deposits. Rock geochemistry data are provided in tabular form.

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Geology, geochemistry, and geophysics of the Fry Canyon uranium/copper project site, southeastern Utah - Indications of contaminant migration

Chemical analyses of water and sediment samples, images depicting resistivity.

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Geophysical and geochemical data from the area of the Pebble Cu-Au-Mo porphyry deposit, southwestern Alaska: Contributions to assessment techniques for concealed mineral resources

Uninterpreted geophysical measurements and geochemical and mineralogical analytical data from samples collected during the summer field seasons from 2007 to 2010. Data are available in a single Geographic Information System (GIS) database.

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Lead isotope determinations from sulfide mineral occurrences--Russian Far East

Data represent work completed when the study ended due to lack of funding. Geologic and site information on each specific deposit or occurrence are provided. Analytical and geologic data are summarized and site descriptions for samples analyzed are listed

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National Geochronological Database

Radiometric ages of geological materials by K-Ar, Rb-Sr, Sm-Nd, fission track, and U-Th-Pb dating methods. A revision of DDS-14 correcting locations and providing the data in more convenient formats.

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National Geochronological Database

Radiometric ages of geological materials by K-Ar, Rb-Sr, Sm-Nd, fission track, and U-Th-Pb dating methods. A revision of DDS-14 correcting locations and providing the data in more convenient formats.

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Pb-concentrations and Pb-isotope ratios in soils collected along an east-west transect across the United States

Analytical results for Pb-concentrations and isotopic ratios from about 150 samples of soil A horizon and about 145 samples of soil C horizon collected along a 4000-km east-west transect across the USA.

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Petrographic and geochemical data for Cenozoic volcanic rocks of the Bodie Hills, California and Nevada

The purpose of this report is to present available petrographic and geochemical data for unmineralized rock samples, principally volcanic rocks and to make those data available to ongoing petrogenetic investigations of these rocks.

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Physical, chemical, and mineralogical data from surficial deposits, groundwater levels, and water composition in the area of Franklin Lake playa and Ash Meadows, California and Nevada

Presents data and describes the methods used to determine the physical attributes, as well as the chemical and mineralogical composition of surficial deposits; groundwater levels; and water composition in this area.

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Preliminary Geologic Map of the Cook Inlet Region, Alaska-- Including parts of the Talkeetna, Talkeetna Mountains, Tyonek, Anchorage, Lake Clark, Kenai, Seward, Iliamna, Seldovia, Mount Katmai, and Afognak 1:250,000-scale quadrangles

Digital geologic map information with a consistent set of attributes, part of a national compilation of similar maps. Available in formats compatible with GIS.

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Preliminary geologic map of the northeast Dillingham quadrangle (D-1, D-2, C-1, and C-2), Alaska

Map, report, and geospatial data on the geology of the northeastern part of the 1:250,000 scale Dillingham quadrangle, Alaska. Includes Ar40/39 radiometric ages, geologic unit descriptions, and correlation of map units.

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Preliminary map of the uranium provinces in the conterminous United States

Scanned image of map drawn at 1:5,000,000 scale, projection probably Lambert Conformal Conic, monochrome.

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Provisional zircon and monazite uranium-lead geochronology for selected rocks from Vermont

Results of zircon and monazite U-Pb geochronologic analyses of 24 rock samples collected from mapped exposures identified while conducting new, detailed (1:24,000-scale) geologic or reconnaissance geologic mapping for the new state map of Vermont.

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Radiometric ages of rocks from Alaska

Radiometric ages of rocks or minerals sampled from Alaska. The data were collected from professional publications and/or received from researchers and used by permission.

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Reconnaissance geologic map of the Kuskokwim Bay region, southwest Alaska

A geologic map constructed primarily from reconnaissance studies from the 1950s to 1990s. The rocks of the map area range from Proterozoic age metamorphic rocks of the Kanektok metamorphic complex to Quaternary age mafic volcanic rocks of Nunivak Island.

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Sediment-hosted stratabound copper deposit model

This report describes key features; identifies tectonic-sedimentary environments; illustrates geochemical, geophysical, and geoenvironmental characteristics; evaluates deposit formation; presents exploration and assessment guides; and lists knowledge gaps

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Spring runoff water-chemistry data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

Periodic sampling of water during the spring of 2010 was carried out to understand the range and timing of variation in pH and metal concentration, and help evaluate variation in water quality during spring runoff.

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Surficial geologic map of parts of the Misheguk Mountain and Baird Mountains quadrangles, Noatak National Preserve, Alaska

Primary surficial units are late Quaternary glacial, glacio-lacustrine, and fluvial deposits. Map and report include radiocarbon dates, geologic units.

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U-Pb zircon age data for selected sedimentary, metasedimentary, and igneous rocks from northern and central Alaska

Contains results of age dating studies interpreted in other reports. Samples in each study shown as separate sheets within Excel files. Analyses of each zircon are listed separately on a sheet according to filtering scheme and type of instrument used.

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Uranium-lead zircon ages and Sr, Nd, and Pb isotope geochemistry of selected plutonic rocks from western Idaho

U-Pb geochronology and isotopic studies of select plutons across the Salmon River suture in western Idaho.

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Water and rock geochemistry, geologic cross sections, geochemical modeling, and groundwater flow modeling for identifying the source of groundwater to Montezuma Well, a natural spring in central Arizona

This report releases data, cross section, and model information related to the identification of travel paths for groundwater supply and principal stratigraphic and structural features that serve as constraints or conduits for groundwater movement.

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