Sound velocities of olivine at high pressures and temperatures and the composition of Earth's upper mantle

Jin S. Zhang, Jay D. Bass

Research output: Contribution to journalArticle

Abstract

We present the elastic properties of San Carlos olivine up to P = 12.8(8) GPa and T = 1300(200) K using Brillouin spectroscopy with CO2 laser heating. A comparison of our results with the global seismic model AK135 yields average olivine content near 410 km depth of about 37% and 43% in a dry and wet (1.9 wt % H2O) upper mantle, respectively. These olivine contents are far less than in the pyrolite model. However, comparisons of our results with regional seismic models lead to very different conclusions. High olivine contents of up to 87% are implied by seismic models of the western U.S. and eastern Pacific regions. In contrast, we infer less than 35% olivine under the central Pacific. Strong variations of olivine content and upper mantle lithologies near the 410 km discontinuity are suggested by regional seismic models.

Original languageEnglish (US)
Pages (from-to)9611-9618
Number of pages8
JournalGeophysical Research Letters
Volume43
Issue number18
DOIs
StatePublished - Sep 28 2016

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Keywords

  • 410 km discontinuity
  • olivine
  • piclogite
  • pyrolite
  • sound velocities

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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