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Title: Thermoelastic Properties of Eclogitic Garnets and Omphacites: Implications for Deep Subduction of Oceanic Crust and Density Anomalies in the Upper Mantle
Abstract

Synchrotron‐based high‐pressure/high‐temperature single‐crystal X‐ray diffraction experiments to ~24 GPa and 700 K were conducted on eclogitic garnets (low‐Fe: Prp28Alm38Grs33Sps1and high‐Fe: Prp14Alm62Grs19Adr3Sps2) and omphacites (low‐Fe: Quad57Jd42Ae1and high‐Fe: Quad53Jd27Ae20), using an externally heated diamond anvil cell. Fitting the pressure‐volume‐temperature data to a third‐order Birch‐Murnaghan equation of state yields the thermoelastic parameters including bulk modulus (KT0), its pressure derivative (KT0), temperature derivative ((∂KT/∂T)P), and thermal expansion coefficient (αT). The densities of the high‐Fe and low‐Fe eclogites were then modeled along typical geotherms of the normal mantle and the subducted oceanic crust to the transition zone depth (550 km). The metastable low‐Fe eclogite could be a reason for the stagnant slabs within the upper range of the transition zone. Eclogite would be responsible for density anomalies within 100–200 km in the upper mantle of Asia.

 
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Award ID(s):
1722969
NSF-PAR ID:
10460791
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Geophysical Research Letters
Volume:
46
Issue:
1
ISSN:
0094-8276
Page Range / eLocation ID:
p. 179-188
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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