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Shear-Induced ringwoodite formation in the Martian shergottite Dar al Gani 670

Greshake, Ansgar and Fritz, Jörg and Böttger, Ute and Goran, Daniel (2013) Shear-Induced ringwoodite formation in the Martian shergottite Dar al Gani 670. Earth and Planetary Science Letters (375), pp. 383-394. Elsevier. ISSN 0012-821X

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Abstract

Shock-produced melt veins in the Martian shergottite Dar al Gani 670 crosscut large olivine crystals. The upper part of one of these crystals appears to be sheared off and displaced along the shock vein. From the olivine–vein interface small lamellae of ringwoodite grow into the host crystal. The ≤1–3 mm wide and up to20 mm long lamellae consist of small bands and blocks and are orientated along specific crystallographic orientations. Texture and composition, i.e., more Fe-rich than the host olivine, indicate that lamellae formed via incoherent diffusion-controlled growth. It is suggested that a combination of high particle velocities and shock-induced defects lead to enhanced diffusion rates. In addition, shearing caused grain size reduction allowing rapid Fe–Mg interchange and induced lattice defects serving as nucleation sites for ringwoodite. Crystallographic orientation of ringwoodite lamellae indicates that during shock deformation the [001]{hk0} slip system was activated in olivine. Natural high-pressure phases in Martian meteorite allow to constrain phase transitions taking place in the inaccessible Earth's mantle. High pressure shear instabilities of olivine at subduction zones in 400–700 km depth are considered being responsible for deep earthquakes. At such p–T-conditions, breakdown of olivine results in formation of ringwoodite filled micro-anti cracks which interact with eachother finally leading to catastrophic shear failure. Our results strongly suggest that shearing itself contributes to a runaway process of enhanced ringwoodite formation and, thus, reinforces catastrophic material failure that may result in deep earthquakes.

Item URL in elib:https://elib.dlr.de/79487/
Document Type:Article
Title:Shear-Induced ringwoodite formation in the Martian shergottite Dar al Gani 670
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Greshake, AnsgarMuseum für Naturkunde, Leibniz-Institut an der Humboldt-Universität zu Berlin, Invalidenstraße 43, 10115 Berlin, GermanyUNSPECIFIED
Fritz, JörgMuseum für Naturkunde, Leibniz-Institut an der Humboldt-Universität zu Berlin, Invalidenstraße 43, 10115 Berlin, GermanyUNSPECIFIED
Böttger, Uteute.boettger (at) dlr.deUNSPECIFIED
Goran, DanielBruker Nano GmbH, Schwarzschildstraße 12, 12489 Berlin, GermanyUNSPECIFIED
Date:28 June 2013
Journal or Publication Title:Earth and Planetary Science Letters
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Page Range:pp. 383-394
Publisher:Elsevier
ISSN:0012-821X
Status:Published
Keywords:Martian Meteorite, Ringwoodite
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):R - Projekt ExoMars
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Experimentelle Planetenphysik
Deposited By: Böttger, Dr.rer.nat. Ute
Deposited On:13 Nov 2013 12:09
Last Modified:31 Jul 2019 19:38

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