Geological Society of America

T192 Advances in Mineral Sciences from Atomistic to Macro Perspectives: Recognition of Dr. Nancy L. Ross, 2024 Roebling Medalist of the Mineralogical Society of America (Posters)

Tuesday, 24 September 2024
8:00 AM - 5:30 PM
Hall D

FAST SEISMIC ANOMALIES UNDER CONTINENTS EXPLAINED BY THE DELAMINATED LOWER CONTINENTAL CRUST – IMPLICATIONS FROM HIGH PRESSURE-TEMPERATURE ELASTICITY OF JADEITE

Paper number: T192-7
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Ming Hao
Texas A&M University, college station, TX
Wen-Yi Zhou
Texas A&M University, college station, TX
Przemyslaw Dera
University of Hawaii at Manoa, Honolulu, HI
Brandon Schmandt
University of New Mexico, Albuquerque, NM
Dongzhou Zhang
University of Chicago, Lemont, IL
Jin Zhang Presenting Author
Texas A&M University, college station, TX

Abstract

Seismic tomography has shown that the shear wave velocities (Vs) under continents, especially under cratons, are extremely fast at 100-200 km depth, which is difficult to explain by low temperatures or high Mg#. Alternatively, delaminated eclogitic lower continental crust has been proposed to account for these fast seismic anomalies. However, the thermoelastic properties of jadeite which constitutes up to 60-80 mol% of clinopyroxene in the potentially delaminated lower continental crust are not well constrained. In this study, we measured the single-crystal elasticity of jadeite by Brillouin spectroscopy under simultaneous high pressure and temperature conditions for the first time. We found that the temperature dependence of Vs of jadeite is extremely small if not negligible. The seismic velocities of the potentially delaminated lower continental crusts were subsequently modeled and found to match the widely observed fast seismic anomalies under cratons between 100-200 km depth.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-401010

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