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Magnetostratigraphy and Clockwise Rotation of the Plio-Pleistocene Mojave River Formation, Central Mojave Desert, California

Pluhar, Christopher J. and Kirschvink, Joseph L. and Adams, Robert W. (1991) Magnetostratigraphy and Clockwise Rotation of the Plio-Pleistocene Mojave River Formation, Central Mojave Desert, California. In: The Mojave River formation, Manix Basin, California: stratigraphy, correlation, magnetostratigraphy, and rotation. Quarterly (San Bernardino County Museum Association). Vol.38. No.2. San Bernardino County Museum Association , Redlands, CA, pp. 31-42. ISBN 24102703.

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Oriented samples collected for paleomagnetic analysis from sediments of the newly-named Mojave River Formation (Nagy & Murray, 1991, this volume) possess stable characteristic components of Natural Remanent Magnetization (NRM). Progressive demagnetization reveals characteristic components of both normal and reversed polarity which are stratigraphically distinct. The oldest sediments exposed within the field area are reversely magnetized and were probably deposited during the early portion of the Matuyama reversed Chron. Stratigraphically higher units contain what appears to be the Olduvai normal Subchron, as well as a shorter normal zone which probably is either the Cobb Mountain or Jaramillo Event. The location of the Brunhes/Matuyama boundary at one site is within an alluvial fanglomerate which grades upward conformably into the lowest unit of the overlying Manix Formation, possibly accounting for the absence of the Bishop ash in the section. Demagnetization data from 143 samples yielding acceptable least-squares lines suggest a net clockwise rotation of 8 ± 2.7° over the past two million years, perhaps with some of the rotation during deposition. This rate of rotation could account easily for larger rotations reported elsewhere in the Mojave Desert on units of Miocene age.

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Kirschvink, Joseph L.0000-0001-9486-6689
Additional Information:© 1991 San Bernardino County Museum Association. Supported partially by NSF grant EAR-8351470 and matching funds from the Chevron Oil Field Research Company, the ARCO Foundation, and the California Institute of Technology Summer Undergraduate Research Fellowship (SURF) program. Contribution No. 4998 from the Division of Geological and Planetary Sciences of the California Institute of Technology.
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Chevron Oil Field Research CompanyUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF) ProgramUNSPECIFIED
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Caltech Division of Geological and Planetary Sciences4998
Series Name:Quarterly (San Bernardino County Museum Association)
Issue or Number:2
Record Number:CaltechAUTHORS:20130124-145516602
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Official Citation:Pluhar, C.J. & J.L. Kirschvink. Magnetostratigraphy and clockwise rotation of the Plio-Plsistocene Mojave River Formation, Central Mojave Desert, California. San Bernardino County Museum Association Quarterly v. 38(2), p. 31-42.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36575
Deposited By: Tony Diaz
Deposited On:15 Apr 2013 18:22
Last Modified:03 Mar 2020 13:01

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