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Dehydration-driven stress transfer triggers intermediate-depth earthquakes.


ABSTRACT: Intermediate-depth earthquakes (30-300?km) have been extensively documented within subducting oceanic slabs, but their mechanics remains enigmatic. Here 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 intermediate-depth 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.

SUBMITTER: Ferrand TP 

PROVIDER: S-EPMC5440692 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Dehydration-driven stress transfer triggers intermediate-depth earthquakes.

Ferrand Thomas P TP   Hilairet Nadège N   Incel Sarah S   Deldicque Damien D   Labrousse Loïc L   Gasc Julien J   Renner Joerg J   Wang Yanbin Y   Green Ii Harry W HW   Schubnel Alexandre A  

Nature communications 20170515


Intermediate-depth earthquakes (30-300 km) have been extensively documented within subducting oceanic slabs, but their mechanics remains enigmatic. Here 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 a  ...[more]

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