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Pacific North America plate tectonics of the Neogene southwestern United States: An update

Atwater, Tanya and Stock, Joann (1998) Pacific North America plate tectonics of the Neogene southwestern United States: An update. In: Integrated earth and environmental evolution of the southwestern United States: the Clarence A. Hall, Jr. volume. Bellwether Pub. , Columbia, MD, pp. 393-420. ISBN 9780966586909. http://resolver.caltech.edu/CaltechAUTHORS:20140415-074340042

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Abstract

We use updated rotations within the Pacific-Antarctica-Africa-North America plate circuit to calculate Pacific-North America plate reconstructions for times since chron 13 (33 Ma). The direction of motion of the Pacific plate relative to stable North America was fairly steady between chrons 13 and 4, and then changed and moved in a more northerly direction from chron 4 to the present (8 Ma to the present). No Pliocene changes in Pacific-North America plate motion are resolvable in these data, suggesting that Pliocene changes in deformation style along the boundary were not driven by changes in plate motion. However, the chron 4 change in Pacific-North America plate motion appears to correlate very closely to a change in direction of extension documented between the Sierra Nevada and the Colorado Plateau. Our best solution for the displacement with respect to stable North America of a point on the Pacific plate that is now near the Mendocino triple junction is that from 30 to 12 Ma the point was displaced along an azimuth of ~N60°W at rate of ~33 mm/yr; from 12 Ma to about 8 Ma the azimuth of displacement was about the same as previously, but the rate was faster (~52 mm/yr); and since 8 Ma the point was displaced along an azimuth of N37°W at a rate of ~52 mm/yr. We compare plate-circuit reconstructions of the edge of the Pacific plate to continental deformation reconstructions of North American tectonic elements across the Basin and Range province and elsewhere in order to evaluate the relationship of this deformation to the plate motions. The oceanic displacements correspond remarkably well to the continental reconstructions where deformations of the latter have been quantified along a path across the Colorado Plateau and central California. They also supply strong constraints for the deformation budgets of regions to the north and south, in Cascadia and northern Mexico, respectively. We examine slab-window formation and evolution in a detailed re-analysis of the spreading geometry of the post-Farallon microplates, from 28 to 19 Ma: Development of the slab window seems linked to early Miocene volcanism and deformation in the Mojave Desert, although detailed correlations await clarification of early Miocene reconstructions of the Tehachapi Mountains. We then trace the post-20 Ma motion of the Mendocino slab window edge beneath the Sierran-Great Valley block and find that it drifted steadily north, then stalled just north of Sutter Buttes at ~4 Ma.


Item Type:Book Section
ORCID:
AuthorORCID
Stock, Joann0000-0003-4816-7865
Additional Information:© 1998 Bellwether Pub. We thank Brian Wernicke and J. Kent Snow for allowing us to use their results in advance of publication. We thank Gene Humphreys, John Crowell, Bruce Luyendyk, Craig Nicholson, Gary Axen, Michael Singer, and Marcy Davis for helpful reviews and Brian Wernicke, Doug Wilson, Gene Humphreys, Rob Twiss, Bob Butler, Wayne Thatcher, and Peter Weigand for helpful conversations, advice, and suggestions. We thank the Hall Symposium participants for lively feedback and Gary Ernst for his reviews, advice, and patient good humor. This work was supported by NSF Grant EAR-9614674 to J. Stock. California Institute of Technology, Division of Geological and Planetary Sciences, Contribution No. 8534.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-9614674
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences8534
Record Number:CaltechAUTHORS:20140415-074340042
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140415-074340042
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44940
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:15 Apr 2014 20:09
Last Modified:04 Dec 2015 19:10

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