TY - JOUR T1 - Contrasted hydrothermal activity along the South-East Indian Ridge (130°E-140°E): From crustal to ultramafic circulation A1 - Boulart,Cedric A1 - Briais,Anne A1 - Chavagnac,Valerie A1 - Revillon,Sidonie A1 - Ceuleneer,Georges A1 - Donval,Jean-Pierre A1 - Guyader,Vivien A1 - Barrere,Fabienne A1 - Ferreira,Nicolas A1 - Hanan,Barry A1 - Hemond,Christophe A1 - Macleod,Sarah A1 - Maia,Marcia A1 - Maillard,Agnes A1 - Merkuryev,Sergey A1 - Park,Sung-Hyun A1 - Ruellan,Etienne A1 - Schohn,Alexandre A1 - Watson,Sally A1 - Yang,Yun-Seok AD - IFREMER, Geosci Marines, Plouzane, France. AD - CNES, IRD, Geosci Environm Toulouse, UMR5563,CNRS,UPS, Toulouse, France. AD - IUEM, Sedisor Lab Domaines Ocean, Brest, France. AD - Inst Univ Europeen Mer, CNRS, Domaines Ocean, Plouzane, France. AD - San Diego State Univ, Dept Geol Sci, San Diego, CA 92182 USA. AD - Univ Sydney, Sch Geol Sci, Sydney, NSW, Australia. AD - IZMIRAN, St Petersburg, Russia. AD - Korea Polar Res Inst, Incheon, South Korea. AD - Univ Tasmania, IMAS, Hobart, Tas, Australia. UR - https://archimer.ifremer.fr/doc/00387/49821/ DO - 10.1002/2016GC006683 KW - hydrothermal plumes KW - mid-ocean ridges KW - South-East Indian Ridge N2 - Using a combined approach of seafloor mapping, MAPR and CTD survey, we report evidence for active hydrothermal venting along the 130°-140°E section of the poorly-known South-East Indian Ridge (SEIR) from the Australia-Antarctic Discordance (AAD) to the George V Fracture Zone (FZ). Along the latter, we report Eh and CH4 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 CH4: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. Y1 - 2017/07 PB - Amer Geophysical Union JF - Geochemistry Geophysics Geosystems SN - 1525-2027 VL - 18 IS - 7 SP - 2446 EP - 2458 ID - 49821 ER -