Paleomagnetism and 40Ar/39Ar geochronologyof the Plio-Pleistocene Boring Volcanic Field: Implications for the geomagnetic polarity time scale and paleosecular variation

Physics of the Earth and Planetary Interiors
By: , and 

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Abstract

Paleomagnetic directions and 40Ar/39Ar ages have been determined for samples of lava flows from the same outcrops, where possible, for 84 eruptive units ranging in age from 3200 ka to 60 ka within the Boring Volcanic Field (BVF) of the Pacific Northwest, USA. This study expands upon our previous results for the BVF, and compares the combined results with the current geomagnetic polarity time scale (GPTS). Lava flows with transitional directions were found within the BVF at the Matuyama-Brunhes and Jaramillo-Matuyama polarity boundaries, and replicate ages corresponding to these and other boundaries have been newly ascertained. Although the BVF data generally agree with GPTS chronozone boundaries, they indicate that onset of the Gauss-Matuyama transition and Olduvai subchron occurred significantly earlier than given in the current time scale calibration. Additional comparisons show that the BVF results are consistent with recent statistical models of geomagnetic paleosecular variation.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Paleomagnetism and 40Ar/39Ar geochronology of the Plio-Pleistocene Boring Volcanic Field: Implications for the geomagnetic polarity time scale and paleosecular variation
Series title Physics of the Earth and Planetary Interiors
DOI 10.1016/j.pepi.2016.07.008
Volume 262
Year Published 2017
Language English
Publisher Elsevier
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center, Volcano Science Center
Description 15 p.
First page 101
Last page 115
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