Incel, S, Schubnel, A, Renner, J et al. (7 more authors) (2019) Experimental evidence for wall-rock pulverization during dynamic rupture at ultra-high pressure conditions. Earth and Planetary Science Letters, 528. 115832. ISSN 0012-821X
Abstract
The mechanisms triggering intermediate and deep earthquakes have puzzled geologists for several decades. There is still no consensus concerning whether such earthquakes are triggered by brittle or ductile mechanisms. We performed a deformation experiment on a synthetic lawsonite-bearing blueschist at a confining pressure of 3 GPa and temperatures from 583 to 1,073 K. After deformation, the recovered sample reveals conjugated shear fractures. Garnet crystals are dissected and displaced along these narrow faults and reveal micro- and nanostructures that resemble natural pulverization structures as well as partial amorphization. Formation of such structures at low confining pressures is known to require high tensile stresses and strain rates and is explained by the propagation of a dynamic shear rupture. The absence of shearing in the pulverized wall rock is taken as evidence that these structures pre-date the subsequent heat-producing frictional slip. In analogy to observations at low pressure we infer that the garnet structures in our experiment result from rapid propagation of a shear fracture even at the high pressure exerted on the sample and thus suggest that brittle deformation is possible at lower crustal to upper mantle depths.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 Elsevier B.V. All rights reserved. This is an author produced version of an article published in Earth and Planetary Science Letters. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | pulverization; high-pressure deformation; dynamic rupture; lawsonite-blueschist; DDIA apparatus; acoustic emissions |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 25 Feb 2020 11:02 |
Last Modified: | 30 Sep 2020 00:38 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.epsl.2019.115832 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:157637 |
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