Geochronology

Study of the age of the earth by dating geological formations, rocks, and fossils.


Results listed by similarity [list alphabetically]
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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40Ar/39Ar data for: Characteristics and 40Ar/39Ar geochronology of the Erdenet Cu-Mo deposit, Mongolia

Full raw argon isotopic data for samples from this deposit. Data are provided in CSV format.

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Ar/Ar geochronology of samples from the Tonopah, Divide, and Goldfield districts, Nevada

Ar/Ar data are reported from minerals and rocks that were collected as part of a mineral resource investigation of this area. Data are provided in CSV format.

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Argon and geochemical data for: 40Ar/39Ar geochronology and petrogenesis of the Table Mountain Shoshonites, Golden, CO

Observational data supporting Argon-Argon geochronological analysis, along with geochemical analyses of basalt samples from this area. Data are provided in CSV format.

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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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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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U-Pb data for Origin of Tin Mineralization in the Sullivan Pb-Zn-Ag Deposit, British Columbia: Constraints from Textures, Geochemistry, and LA-ICP-MS U-Pb Geochronology of Cassiterite

Uranium and Thorium concentration and isotopic ratios of Uranium, Thorium, and lead in 469 cassiterite (SnO2) samples collected in the underground Sullivan Mine near Kimberley, British Columbia. These measurements improve the estimates of the timing of cassiterite ore mineralization in a classic sedimentary exhalite mineral deposit.

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U-Pb geochronology and tectonic implications of a Silurian ash in the Farewell Terrane, Alaska

The Farewell terrane is an exotic continental fragment in interior Alaska that during the early Paleozoic was the site of a passive margin. We report a <sup>238</sup>U/<sup>206</sup>Pb zircon age of 432.9±3.0 Ma from a Farewell terrane ash in Mt. McKinle

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U-Pb geochronology of tin deposits associated with the Cornubian Batholith of southwest England: Direct dating of cassiterite by in situ LA-ICPMS

The Cornwall and Devon vein- and greisen-type copper and tin deposits of southwest England are spatially and genetically related to shallow-seated granitic intrusions. These late Variscan intrusions, collectively known as the Cor

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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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Garnet Lu-Hf Ages and Isotope Data for the Stibnite, Idaho Area

Garnet Lu-Hf ages of the schist of Moores Station Formation and a cross-cutting garnetiferous felsic dike in this area. These ages provide part of the early geologic history leading up to ore deposition. Data are provided in CSV format.

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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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Geochronologic data from xenoliths near the Stillwater Complex, Montana

U-Pb isotopic data collected on zircon in xenoliths from the Sliderock Mountain and Susie Peak plutons using the sensitive high-resolution ion microprobe-reverse geometry (SHRIMP-RG) at Stanford University. Data are provided in CSV format, locations are provided in shapefile format.

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In situ LA-ICPMS U–Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to the Tertiary

Cassiterite , a main ore mineral in tin deposits, is suitable for U–Pb isotopic dating because of its relatively high U/Pb ratios and typically low common Pb. We report a LA-ICPMS analytical procedure for U–Pb dating of

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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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Isotopic ratios and element concentrations of U-Pb and Sm-Nd for scheelite petrochronology

Instrument, standard, and sample data from application of in situ laser ablation-inductively coupled plasma-mass spectrometry dating of scheelite in thin section, and sample data from isotope dilution thermal ionization mass spectrometry scheelite dating. Data are provided in CSV format.

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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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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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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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Two-event lode-ore deposition at Butte, USA: 40Ar/39Ar and U-Pb documentation of Ag-Au-polymetallic lodes overprinted by younger stockwork Cu-Mo ores and penecontemporaneous Cu lodes

<p id="sp0015">The ore-genesis model for world-class deposits of the Butte mining district, Montana, USA, is deep pre-Main Stage porphyry Cu-Mo and overlying Main Stage Ag-Zn-Cu zoned-lode deposits, both of which formed from hydrothermal fluids driven by

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U-Pb data for: In situ LA-ICPMS U-Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to Tertiary

Data supporting a LA-ICPMS analytical procedure for dating cassiterite, a main ore mineral in tin deposits, with no need for an independently dated matrix-matched cassiterite standard. Data are provided in Microsoft Excel and CSV formats.

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U-Pb zircon data for: Cretaceous plutonic rocks of western Glacier Bay National Park and Preserve

Geochronologic analyses to determine the ages of the plutonic rocks in the Glacier Bay area. Five samples were dated by laser ablation-inductively coupled plasma mass spectrometry U-Pb methods. These analyses contribute to understanding the geologic history of this area. Sample locations and characteristics, along with measured isotopic ratios and calculated ages are provided in CSV format.

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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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Zircon U-Pb age and trace element data for Cenozoic igneous rocks in the Tonopah area, Nevada

U-Pb ages and concentrations of selected trace elements were analyzed in zircon crystals from nine samples of Cenozoic igneous rocks collected in this area. Data are provided in CSV format.

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