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This data release includes electron 40Ar/39Ar collected at the U.S. Geological Survey for samples from the Day Nui Con Voi metamorphic massif, Vietnam. Rock samples were collected by Meng-Wan Yeh, Michael J. Kunk and Robert P Wintsch in 2011. Mineral separates were prepared and aliquots of amphibole, muscovite, phlogopite, biotite, and potassium feldspar were analyzed by the 40Ar/39Ar method at the U.S. Geological Survey Bascom ARgon Dating (BARD) Laboratory in Reston, Virginia. The 40Ar/39Ar data constrain the timing of exhumation of rocks within the massif.
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USGS Geochron is a database of geochronological and thermochronological dates and data. The data set contains published ages, dates, analytical information, sample metadata including location, and source citations. The following analytical techniques are represented in the data set: 40Ar/39Ar, K-Ar, U-Th-Pb, Sm-Nd, Rb-Sr, Lu-Hf, fission track, luminescence, U-series in situ, (U-Th)/He, and Re-Os. This data set incorporates data previously hosted in the National Geochronological Database (Sloan and others, 2003), as well as data from published journal articles and ScienceBase data releases. These data are primarily from the United States, but data from other parts of the world are also included. First posted January...
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Samples of vein-type magmatic-steam alunite were collected over several field seasons from five mines and prospects (L&N, Mt. Edna, Christmas, upper Mineral Products, and Close In) in the Alunite Ridge and Deer Trail Mountain area, Marysvale, Utah, as well as a sample from the Deer Trail mine workings from which sericite was separated. The magmatic-steam alunite and sericite were analyzed by the 40Ar/39Ar method to constrain the timing and duration of magmatic activity associated with the intrusion of two porphyry stocks beneath Alunite Ridge and Deer Trail Mountain. In addition, a sample of a highly altered rhyolitic quartz porphyry dike was collected from the upper Mineral Products mine, from which zircons were...
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The Central Virginia Seismic Zone (CVSZ) is an area of historically increased earthquake activity that is of particular importance due to its proximity to many well-populated regions in the Virginia Piedmont. Notably, the epicentral region of the 2011 magnitude (M)5.8 earthquake in Mineral, Virginia falls within the CVSZ (Horton and Williams, 2012), making this region relevant not just historically, but also in more recent times. Thus, the U.S. Geological Survey is focusing on detailed bedrock mapping of the central Virginia Piedmont to better understand bedrock and fault geometry, fault history, and seismic risk potential. Though the central Virginia Piedmont has been mapped to some extent in previous studies (Hopkins,...
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Tephra samples were collected by Leah Morgan (now at the U.S. Geological Survey (USGS)) from the Hugub Area, Kesem-Kebena-Dulecha, Afar, Ethiopia. Sanidine grains were separated from the bulk sample and analyzed by argon geochronology at the Scottish Universities Environmental Research Centre, Scotland. The data indicate that the age of the Hugub Bed, which is rich in archarological artifacts, is ca. 500 ka. These results have broad implications in understanding late Acheulean archaeology in Ethiopia.


    map background search result map search result map Argon data for Hugub Area, Kesem-Kebena-Dulecha, Ethiopia Argon and SHRIMP-RG Data for Magmatic Steam Alunite, Sericite, and Zircon from Alunite Ridge and Deer Trail Mountain, Marysvale, Utah 40Ar/39Ar isotopic data from the Day Nui Con Voi metamorphic massif, Vietnam 238U/206Pb SHRIMP, 40Ar/39Ar geochronologic, and geochemical data from the Central Virginia Piedmont Argon data for Hugub Area, Kesem-Kebena-Dulecha, Ethiopia Argon and SHRIMP-RG Data for Magmatic Steam Alunite, Sericite, and Zircon from Alunite Ridge and Deer Trail Mountain, Marysvale, Utah 238U/206Pb SHRIMP, 40Ar/39Ar geochronologic, and geochemical data from the Central Virginia Piedmont 40Ar/39Ar isotopic data from the Day Nui Con Voi metamorphic massif, Vietnam