ISTerre seminar

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[Annulé/Canceled] The Metamorphic Record of Deep Subduction Faults

Annulé

Tuesday 31 January 2023 - 11h00

Samuel Angiboust - ENS Lyon
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We herein review the occurrence of recent examples highlighting how exhumed metamorphic rocks record ancient subduction fluid-rock interaction events in the 20-80km depth range. These observations, that complement available geophysical data, indicate that fluid flow appears to occur as pulses that transiently percolate through the rock volume. As this interface-parallel flow proceeds, it changes the mechanical state of the critically saturated rock volume, triggering unstable slip events as documented by the presence of foliated cataclasites and locally pseudotachylytes. Some of the plate interface fluids manage to infiltrate the overlying mantle wedge environment, potentially creating instabilities in the hydromechanical state of the rock and producing microseismicity, as recorded by brecciated jadeitites. These observations emphasize the key role of metamorphic fluid production in maintaining the system in a critically unstable state, ready to break.

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Organizing team : Ondes et structures

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères