New constraints on carbonation associated with brecciation in hyperextended margins (example of Iberia and Newfoundland margins)

• Published in: Terra Nova
• Main Authors: Picazo, Suzanne, Lafay, Romain, Faucheux, Vincent, Vennemann, Torsten
• Other Authors: Université de Lausanne = University of Lausanne (UNIL), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Ecole et Observatoire des Sciences de la Terre (EOST), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Newfoundland
• Online Access: https://hal.umontpellier.fr/hal-02134231; https://doi.org/10.1111/ter.12383

International audience The sequestration of CO2 occurs naturally in (ultra)‐mafic rocks by carbonation processes and is commonly noted in areas of the seafloor where mantle lithologies are exhumed. As well as carbonation, mantle exhumation is also responsible for rock brecciation. The relationship between carbonation and brecciation is not well constrained. A temporal evolution from syn‐ to post‐tectonic carbonation and brecciation is proposed in line with progressive mantle exhumation. Using a petrological study of brecciated material from IODP drill cores of the Iberia–Newfoundland conjugated margins, we relate crack–seal veins to tectonic brecciation, authigenic calcite with scalenohedral structure to hydraulic brecciation and reworked clasts within cement to (tectono)‐sedimentary processes. Oxygen isotope compositions reveal late‐staged < 50°C carbonate generation in the proximal part of the ocean–continent transition, which have followed an earlier phase of sub‐seafloor carbonate generation. The results are crucial to understand CO2 exchange within the reworked sub‐seafloor in passive margins and oceanic systems.