BRGM - Bureau de Recherches Géologiques et Minières (BRGM), ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327 : UMR7327, INSU - CNRS - Institut national des sciences de l'Univers, UO - Université d'Orléans : UMR7327
1GR - Géosciences Rennes (Bâtiment 15 - Université de Rennes 1 - Campus de Beaulieu -263 Av du général Leclerc- CS 74205 - 35042 Rennes Cedex - France - France)
Abstract : Carbonation of mantle rocks during mantle exhumation is reported in present-day oceanic settings, both at mid-ocean ridges and ocean-continent transitions (OCTs). However, the hydrothermal conditions of carbonation (i.e., fluid sources, thermal regimes) during mantle exhumation remain poorly constrained. We focus on an exceptionally well-preserved fossil OCT where mantle rocks have been exhumed and carbonated along a detachment fault from underneath the continent to the seafloor along a tectonic Moho. Stable isotope (oxygen and carbon) analyses on calcite indicate that carbonation resulted from the mixing between serpentinization-derived fluids at ~175 °C and seawater. Strontium isotope compositions suggest interactions between seawater and the continental crust prior to carbonation. This shows that carbonation along the tectonic Moho occurs below the continental crust and prior to mantle exhumation at the seafloor during continental breakup.
https://hal-insu.archives-ouvertes.fr/insu-03469219 Contributor : Nathalie PothierConnect in order to contact the contributor Submitted on : Friday, December 10, 2021 - 11:05:10 AM Last modification on : Thursday, May 19, 2022 - 4:35:06 PM Long-term archiving on: : Friday, March 11, 2022 - 6:49:57 PM
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Rémi Coltat, Philippe Boulvais, Yannick Branquet, Antonin Richard, Alexandre Tarantola, et al.. Moho carbonation at an ocean-continent transition. Geology, Geological Society of America, 2022, 50 (3), pp.278-283. ⟨10.1130/G49363.1⟩. ⟨insu-03469219⟩