Eclogite breccias in a subducted ophiolite: A record of intermediate-depth earthquakes? - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Geology Année : 2012

Eclogite breccias in a subducted ophiolite: A record of intermediate-depth earthquakes?

Résumé

Understanding processes acting along the subduction interface is crucial to assess lithospheric-scale coupling between tectonic plates and mechanisms causing intermediate-depth seismicity. Despite a wealth of geophysical studies aimed at better characterizing the subduction interface, we still lack critical data constraining processes responsible for seismicity within oceanic subduction zones. We herein report the finding of eclogite breccias, formed at ∼80 km depth during subduction, in an almost intact 10-km-scale fragment of exhumed oceanic lithosphere (Monviso ophiolite, Western Alps). These eclogite breccias correspond to meter-sized blocks made of 1-10 cm fragments of eclogite mylonite cemented by interclast omphacite, lawsonite, and garnet, and were later embedded in serpentinite in a 30-150-m-wide eclogite facies shear zone. At the mineral scale, omphacite crack-seal veins and garnet zoning patterns also show evidence for polyphased fracturing-healing events. Our observations suggest that a possible seismic brecciation occurred in the middle part of the oceanic crust, accompanied by the input of externally derived fluids. We also conclude that these eclogite breccias likely mark the locus of an ancient fault zone associated with intraslab, intermediate-depth earthquakes at ∼80 km depth.
Fichier non déposé

Dates et versions

insu-00723238 , version 1 (08-08-2012)

Identifiants

Citer

Samuel Angiboust, Philippe Agard, P. Yamato, Hugues Raimbourg. Eclogite breccias in a subducted ophiolite: A record of intermediate-depth earthquakes?. Geology, 2012, 40 (8), pp.707-710. ⟨10.1130/G32925.1⟩. ⟨insu-00723238⟩
131 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More