Plutonic processes in transitional oceanic plateau crust: Structure, age and emplacement of the South Rallier du Baty laccolith, Kerguelen Islands

• Published in: Terra Nova
• Main Authors: Ponthus, Léandre, de Saint Blanquat, Michel, Guillaume, Damien, Le Romancer, Marc, Pearson, Norman, O'Reilly, Suzanne, Grégoire, Michel
• Other Authors: Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS), Géoarchitecture : Territoires, Urbanisation, Biodiversité, Environnement, Université de Rennes (UR)-Université de Brest (UBO), Macquarie University Sydney, Institut Polaire Français Paul Emile Victor, Centre National de la Recherche Scientifique
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: alkaline magmatism; Kerguelen; oceanic plateau; pluton emplacement; syenite intrusion; [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics; [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography; Kerguelen Islands
• Online Access: https://hal.science/hal-03024359; https://hal.science/hal-03024359/document; https://hal.science/hal-03024359/file/2020-Ponthusetal-SRBIC%20%281%29.pdf; https://doi.org/10.1111/ter.12471

International audience The syenitic rocks of South Rallier du Baty Intrusive Complex (SRBIC) represent in- trusions into the oceanic plateau basalts of the south-western Kerguelen Islands. The SRBIC was previously interpreted as a typical ring complex due to magma emplace- ment with cauldron subsidence. Our new structural and geochronological data reveal that it is a laccolith built between 11.6 and 7.9 Ma by successive injections of magma sheets around the crust–mantle boundary, with an average injection rate between 0.8 and 1.4 × 10−4 km3/year. These results establish strong similarities between the SRBIC, the only recorded example of a felsic laccolith in an oceanic intraplate setting, and many continental plutons emplaced in various geodynamic setting. The SRBIC thus has the characteristics of a continental plutonic complex emplaced in an oceanic plateau crust. We postulate the critical parameter relevant to causing such similari- ties and plutonic magmatism is crustal thickness.