24 Mineral Physics Research Aspects Related to Deep Earth’s Interior and Phenomena I

Wednesday, 24 May 2017
8:30 AM - 11:50 AM
Room 318B

ELASTICITY CHANGE ACROSS THE OLIVINE-WADSLEYITE TRANSITION AND ITS IMPLICATIONS FOR THE COMPOSITION AND DYNAMICS NEAR THE 410 DISCONTINUITY

Paper number: 24-2
Program: Theme Sessions
Time: 8:35 AM – 8:55 AM

Authors

  • Jin Zhang Presenting Author
    University of New Mexico, Albuquerque, NM
  • Jay D. Bass
    COMPRES, and University of Illinois Urbana-Champaign, Urbana, IL

Abstract

Single-crystal elasticity of Fe-bearing olivine has been measured up to the pressure temperature conditions close to those at 410 km depth in the Earth’s interior. Combining with previous single-crystal sound velocity measurements of olivine with similar composition, a best-fit thermal elastic model of olivine can be inverted. Velocity jump across the olivine-wadsleyite transition can thus be calculated from the obtained thermal elastic models. We found that a large lateral variation in composition near the 410 km discontinuity is required to explain the observed differences between different regional seismic models. Based on the obtained single-crystal elasticity model, elastic anisotropy of olivine is predicted to slightly decrease with depth, still remains to be high at 410 km depth. Assuming a pyrolitic mantle composition, we expect a large anisotropy decrease across the 410 discontinuity if mantle flow existed in the adjacent regions.

Geological Society of America Abstracts with Programs. Vol. 49, No. 4

doi: 10.1130/abs/2017CD-292445

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