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Science 23 July 1993:
Vol. 261. no. 5120, pp. 460 - 463
DOI: 10.1126/science.261.5120.460
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Articles

Small-Scale Convective Instability and Upper Mantle Viscosity Under California

George Zandt 1 and Charles R. Carrigan 1

1 Institute of Geophysics and Planetary Physics, Earth Sciences Division, L-202, Lawrence Livermore National Laboratory, Livermore, CA 94550

Thermal calculations and convection analysis, constrained by seismic tomography results, suggest that a small-scale convective instability developed in the upper 200 kilometers of the mantle under California after the upwelling and cooling of asthenosphere into the slab window associated with the formation of the San Andreas transform boundary. The upper bound for the upper mantle viscosity in the slab window, 5 x 1019 pascal seconds, is similar to independent estimates for the asthenosphere beneath young oceanic and tectonically active continental regions. These model calculations suggest that many tectonically active continental regions characterized by low upper mantle seismic velocities may be affected by time-dependent small-scale convection that can generate localized areas of uplift and subsidence.

Submitted on January 19, 1993
Accepted on May 20, 1993


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Tectonics of Pliocene removal of lithosphere of the Sierra Nevada, California.
C. H. Jones, G. L. Farmer, and J. Unruh (2004)
GSA Bulletin 116, 1408-1422
   Abstract »    Full Text »    PDF »
Topographic response to mantle lithosphere removal in the southern Sierra Nevada region, California.
J. Saleeby and Z. Foster (2004)
Geology 32, 245-248
   Abstract »    Full Text »    PDF »
Osmium Isotopic Evidence for Mesozoic Removal of Lithospheric Mantle Beneath the Sierra Nevada, California.
C.-T. Lee, Q. Yin, R. L. Rudnick, J. T. Chesley, and S. B. Jacobsen (2000)
Science 289, 1912-1916
   Abstract »    Full Text »


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Science. ISSN 0036-8075 (print), 1095-9203 (online)