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Title: Dehydration-driven stress transfer triggers intermediate-depth earthquakes

Intermediate-depth earthquakes (30–300 km) have been extensively documented within subducting oceanic slabs, but their mechanics remains enigmatic. Here in this paper we decipher the mechanism of these earthquakes by performing deformation experiments on dehydrating serpentinized peridotites (synthetic antigorite-olivine aggregates, minerals representative of subduction zones lithologies) at upper mantle conditions. At a pressure of 1.1 gigapascals, dehydration of deforming samples containing only 5 vol% of antigorite suffices to trigger acoustic emissions, a laboratory-scale analogue of earthquakes. At 3.5 gigapascals, acoustic emissions are recorded from samples with up to 50 vol% of antigorite. Experimentally produced faults, observed post-mortem, are sealed by fluid-bearing micro-pseudotachylytes. Microstructural observations demonstrate that antigorite dehydration triggered dynamic shear failure of the olivine load-bearing network. These laboratory analogues of intermediatedepth earthquakes demonstrate that little dehydration is required to trigger embrittlement. We propose an alternative model to dehydration-embrittlement in which dehydration-driven stress transfer, rather than fluid overpressure, causes embrittlement.
Authors:
ORCiD logo [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [1] ;  [4] ; ORCiD logo [5] ;  [6] ;  [1]
  1. PSL Research Univ., Paris (France); Centre National de la Recherche Scientifique (CNRS), Paris (France). Lab. de Geologie
  2. Univ. Lille, Lille (France). Unite Materiaux et Transformations
  3. Univ. Pierre et Marie Curie, Paris (France). Institut des Sciences de la Terre de Paris
  4. Ruhr Univ., Bochum (Germany). Inst. fur Geologie, Mineralogie und Geophysik
  5. Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources (CARS)
  6. Univ. of California, Riverside, CA (United States). Dept. of Earth Science
Publication Date:
Grant/Contract Number:
FG02-94ER14466; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Univ. of Chicago, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); L'Agence Nationale de la Recherche
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Tectonics; Geophysics; Mineralogy; Seismology
OSTI Identifier:
1424032