Abstract

Tibetan ophiolites are shallow mantle material and crustal slabs that were subducted as deep as the mantle transition zone, a conclusion supported by the discovery of high-pressure phases like inverse ringwoodite in these sequences. Ringwoodite, Mg2SiO4, exhibits the normal spinel structure, with Mg in the octahedral A site and Si in the tetrahedral B site. Through A and B site-disorder, the inverse spinel has four-coordinated A cations and the six-coordinated site hosts a mixture of A and B cations. This process affects the density and impedance contrasts across the boundaries in the transition zone and seismic-wave velocities in this portion of the Earth. We report the first synthesis at high pressure (20 GPa) and high temperature (1600 °C) of a Cr-bearing ringwoodite with a completely inverse-spinel structure. Chemical, structural, and computational analysis confirm the stability of inverse ringwoodite and add further constraints to the subduction history of the Luobusa peridotite of the Tibetan ophiolites.

Details

Title
Synthesis of inverse ringwoodite sheds light on the subduction history of Tibetan ophiolites
Author
Bindi, Luca 1   VIAFID ORCID Logo  ; Griffin, William L 2 ; Panero, Wendy R 3 ; Sirotkina, Ekaterina 4 ; Bobrov, Andrey 5 ; Irifune, Tetsuo 6 

 Dipartimento di Scienze della Terra, Università di Firenze, Florence, Italy; CNR-Istituto di Geoscienze e Greorisorse, Florence, Italy 
 ARC Centre of Excellence for Core to Crust Fluid Systems and GEMOC, Department of Earth and Planetary Sciences, Macquarie University, Sydney, Australia 
 School of Earth Sciences, Ohio State University, Columbus, Ohio, USA 
 Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academy of Sciences, Moscow, Russia; Department of Petrology, Geological Faculty, Moscow State University, Moscow, Russia 
 Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academy of Sciences, Moscow, Russia; Department of Petrology, Geological Faculty, Moscow State University, Moscow, Russia; Institute of Experimental Mineralogy of Russian Academy of Sciences, Chernogolovka, Russia 
 Geodynamics Research Center, Ehime University, Matsuyama, Japan; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan 
Pages
1-8
Publication year
2018
Publication date
Apr 2018
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2021297406
Copyright
© 2018. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.