Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5787415 | Physics of the Earth and Planetary Interiors | 2017 | 15 Pages |
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 3200Â ka to 60Â 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.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geophysics
Authors
Jonathan T. Hagstrum, Robert J. Fleck, Russell C. Evarts, Andrew T. Calvert,