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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.

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.

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.

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.

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.

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.

A compilation of K-Ar-ages for southern California

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

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.

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.

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.

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.

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.

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.

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.