Ar Dating of the Kern River Ash Bed and Related Tephra Layers: Implications for the Stratigraphy of Petroleum-Bearing Formations in the San Joaquin Valley, California
ARTICLE IN PRESS Quaternary International 178 (2008) 246–260 Geochemical correlation and 40Ar/39Ar dating of the Kern River ash bed and related tephra layers: Implications for the stratigraphy of petroleum-bearing formations in the San Joaquin Valley, California Dirk Barona,Ã, Robert M. Negrinia, Elizabeth M. Goloba, Don Millerb, Andrei Sarna-Wojcickic, Robert J. Fleckc, Bradley Hackerd, Alex Erendie aDepartment of Physics and Geology, California State University, Bakersfield, 9001 Stockdale Highway, Bakersfield, CA 93311, USA bBankers Petroleum, 601 East Daily Drive, Camarillo, CA 93010, USA cU.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA dDepartment of Earth Science, University of California, Santa Barbara, CA 93106, USA eChevron Corporation, Bakersfield, CA 93311, USA Available online 27 March 2007 Abstract The Kern River ash (KRA) bed is a prominent tephra layer separating the K and G sands in the upper part of the Kern River Formation, a major petroleum-bearing formation in the southern San Joaquin Valley (SSJV) of California. The minimum age of the Kern River Formation was based on the tentative major-element correlation with the Bishop Tuff, a 0.75970.002 Ma volcanic tephra layer erupted from the Long Valley Caldera. We report a 6.1270.05 Ma 40Ar/39Ar date for the KRA, updated major-element correlations, trace-element correlations of the KRA and geochemically similar tephra, and a 6.070.2 Ma 40Ar/39Ar age for a tephra layer from the Volcano Hills/Silver Peak eruptive center in Nevada. Both major and trace-element correlations show that despite the similarity to the Bishop Tuff, the KRA correlates most closely with tephra from the Volcano Hills/Silver Peak eruptive center.
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