Contrasted hydrothermal activity along the South-East Indian Ridge (130°E-140°E): From crustal to ultramafic circulation

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Boulart, Cédric, Briais, Anne, Chavagnac, Valérie, Révillon, Sidonie, Ceuleneer, Georges, Donval, Jean-Pierre, Guyader, Vivien, Barrere, Fabienne, Ferreira, Nicolas, Hanan, Barry, Hémond, Christophe, C, Macleod, Sarah, Maia, Marcia, Maillard, Agnès, Merkuryev, Sergey, Park, Sung-Hyun, Ruellan, Étienne, Schohn, Alexandre, Watson, Sally, Yang, Yun-Seok
• 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), Dynamique terrestre et planétaire (DTP), Université Toulouse III - Paul Sabatier (UT3), Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Tectonophysique, Université de Nantes (UN), Unité Géosciences Marines (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Department of Geological Sciences San Diego State Univ (Geology SDSU), San Diego State University (SDSU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics; [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology; Antarc*; Antarctic; Southern Ocean
• Online Access: https://hal.univ-brest.fr/hal-01968339; https://hal.univ-brest.fr/hal-01968339/document; https://hal.univ-brest.fr/hal-01968339/file/2016GC006683.pdf; https://doi.org/10.1002/2016GC006683

International audience Using a combined approach of seafloor mapping, MAPR and CTD survey, we report evidence for active hydrothermal venting along the 1308-1408E section of the poorly-known SouthEast Indian Ridge (SEIR) from the Australia-Antarctic Discordance (AAD) to the George V Fracture Zone (FZ). Along the latter, we report Eh and CH 4 anomalies in the water column above a serpentinite massif, which unambiguously testify for ultramafic-related fluid flow. This is the first time that such circulation is observed on an intermediate-spreading ridge. The ridge axis itself is characterized by numerous off-axis volcanoes, suggesting a high magma supply. The water column survey indicates the presence of at least ten distinct hydrothermal plumes along the axis. The CH 4 :Mn ratios of the plumes vary from 0.37 to 0.65 denoting different underlying processes, from typical basalt-hosted to ultramafic-hosted high-temperature hydrothermal circulation. Our data suggest that the change of mantle temperature along the SEIR not only regulates the magma supply, but also the hydrothermal activity. The distribution of hydrothermal plumes from a ridge segment to another implies secondary controls such as the presence of fractures and faults along the axis or in the axial discontinuities. We conclude from these results that hydrothermal activity along the SEIR is controlled by magmatic processes at the regional scale and by the tectonics at the segment scale, which influences the type of hydrothermal circulation and leads to various chemical compositions. Such variety may impact global biogeochemical cycles, especially in the Southern Ocean where hydrothermal venting might be the only source of nutrients.