Convective thermal instabilities in the wake of the migrating Mendocino triple junction, California

Mian Liu, George Zandt

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Whether the high seismic-velocity anomalies in the upper mantle under California represent cold downwelling mantle flow or fragments of the subducted Farallon plate has important implications for mantle dynamics related to the tectonic history of western North America. We investigate the former possibility by simulating the time-dependent thermal evolution in the asthenosphere beneath California, in the wake of the migrating Mendocino triple junction (MTJ), using a two-dimensional model that represents a transect parallel to the direction of the MTJ migration. For viscosity within the typical range for the asthenosphere beneath active tectonic regions (1×1018 - 2×1019 Pa s), our model predicts vigorous small-scale convection characterized by periodic formation of cold downwelling flows near the southern edge of the migrating Gorda plate. Within the relevant time frame, the predicted convective thermal structures are comparable to the major mantle features shown by seismic imaging.

Original languageEnglish (US)
Article number96GL00727
Pages (from-to)1573-1576
Number of pages4
JournalGeophysical Research Letters
Volume23
Issue number13
DOIs
StatePublished - Jan 1 1996

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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