TY - JOUR

T1 - Contrasted hydrothermal activity along the South-East Indian Ridge (130°E–140°E)

T2 - From crustal to ultramafic circulation

AU - Boulart, Cédric

AU - Briais, Anne

AU - Chavagnac, Valérie

AU - Révillon, Sidonie

AU - Ceuleneer, Georges

AU - Donval, Jean Pierre

AU - Guyader, Vivien

AU - Barrere, Fabienne

AU - Ferreira, Nicolas

AU - Hanan, Barry

AU - Hémond, Christophe

AU - Macleod, Sarah

AU - Maia, Marcia

AU - Maillard, Agnès

AU - Merkuryev, Sergey

AU - Park, Sung Hyun

AU - Ruellan, Etienne

AU - Schohn, Alexandre

AU - Watson, Sally

AU - Yang, Yun Seok

PY - 2017/1/1

Y1 - 2017/1/1

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.

AB - 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.

KW - hydrothermal plumes

KW - mid-ocean ridges

KW - South-East Indian Ridge

UR - http://www.scopus.com/inward/record.url?scp=85021726592&partnerID=8YFLogxK

U2 - 10.1002/2016GC006683

DO - 10.1002/2016GC006683

M3 - Article

AN - SCOPUS:85021726592

VL - 18

SP - 2446

EP - 2458

JO - Geochemistry, Geophysics, Geosystems

JF - Geochemistry, Geophysics, Geosystems

SN - 1525-2027

IS - 7

ER -