Article in Geology—by Kreemer and Gordon: Pacific plate deformation from horizontal thermal contraction


This article was recently published in the journal Geology:

Pacific plate deformation from horizontal thermal contraction

By Corné Kreemer (Nevada Bureau of Mines and Geology, and Seismological Laboratory, University of Nevada, Reno) and Richard G. Gordon (Department of Earth Science, Rice University)

Geology, October 2014, v. 42, p. 847-850, first published on August 15, 2014, doi:10.1130/G35874.1

Abstract: The central approximation of plate tectonics is that the plates are rigid, which gives the theory its rigor and predictive power. Space geodetic measurements are consistent with the rigidity of stable plate interiors, but some failures of plate-circuit closure, in particular of oceanic plates, indicate that plates may be measurably non-rigid. We explore the hypothesis that horizontal thermal contraction causes deformation of oceanic plates. Here we show significant expected displacement fields due to thermal contraction for the Pacific plate based on a previously proposed relationship between seafloor age and strain rate and on two end-member assumptions on how strain compatibility is enforced. The predicted maximum 2.2 mm/yr southeastward motion of the northeastern part of the plate relative to the Pacific-Antarctic Rise may contribute to a large part of the non-closure of the Pacific–North America plate motion circuit. Our predicted displacement rates cannot (yet) be confirmed by current space geodetic data and will require seafloor geodesy with 1 mm/yr accuracy. The spatial distribution of predicted moment rate agrees reasonably well with that of intraplate earthquake epicenters, similar to what is observed for plate boundary zones. Our results suggest that plate-scale horizontal thermal contraction is significant, and that it may be partly released seismically.

Both this new article by Kreemer and Gordon listed above and a 2009 article by Chris Henry listed below were on GSA’s “Most-Read Articles during September 2014.”

Uplift of the Sierra Nevada, California
By Christopher D. Henry (Nevada Bureau of Mines and Geology)
Geology, June 2009, v. 37, p. 575-576, doi:10.1130/focus062009.1

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