V14A-02
Structure and Dynamics of the Southeast Indian Ridge and Off-axis Volcanism, 129°E to 140°E: Preliminary Results of the STORM Cruise
Monday, 14 December 2015: 16:15
306 (Moscone South)
Anne Briais1, Fabienne Barrere2, Cedric Boulart3, Georges Ceuleneer2, Nicolas Ferreira4, Barry B Hanan5, Christophe Hemond6, Sarah MacLeod7, Marcia Maia8, Agnès Maillard9, Sergey Alexandrovich Merkuryev10, Sung-Hyun Park11, Sidonie Revillon12, Etienne Ruellan2, Alexandre Schohn6, Sally Joan Watson13, Yun-Seok Yang11 and STORM cruise scientific party, (1)Observatory Midi-Pyrenees, Toulouse, France, (2)University of Toulouse, CNRS/UPS/IRD GET, Toulouse, France, (3)IFREMER, Plouzané, France, (4)Laboratoire Domaines Océaniques, CNRS-UBO, Plouzané, France, (5)San Diego State University, Geological Sciences, San Diego, CA, United States, (6)Université de Brest, CNRS UBO, Laboratoire Domaines Océaniques, Plouzané, France, (7)University of Sydney, EarthByte Group, School of Geosciences, Sydney, Australia, (8)CNRS, Paris Cedex 16, France, (9)GET Géosciences Environnement Toulouse, Toulouse, France, (10)Saint Petersburg State University, Insitute of Earth Sciences, St. Petersburg, Russia, (11)Korea Polar Research Institute, Incheon, South Korea, (12)UBO IUEM, Plouzane, France, (13)University of Tasmania, Hobart, Australia
Abstract:
We present observations of the South-East Indian Ridge (SEIR) collected during the STORM cruise (South Tasmania Ocean Ridge and Mantle) on the N/O L'Atalante early 2015. The SEIR between Australia and Antarctica displays large variations of axial morphology despite an almost constant intermediate spreading rate. The Australia-Antarctic Discordance (AAD) between 120°E and 128°E is a section of the mid-ocean ridge where the magma budget is abnormally low, and which marks the boundary between Indian and Pacific mantle domains with distinct geochemical isotopic compositions. The STORM project focuses on the area east of the discordance from 128 to 140°E, where gravity highs observed on satellite-derived maps of the flanks of the SEIR reveal numerous volcanic seamounts. A major objective of the STORM cruise was to test the hypothesis of a mantle flow from the Pacific to the Indian domains. We collected multibeam bathymetry and magnetic data between 136 and 138°E to map off-axis volcanic ridges up to 10 Ma-old crust. We mapped the SEIR axis between 129 and 140°E, and the northern part of the George V transform fault. We collected rock samples on seamounts and in the transform fault, basaltic glass samples along the ridge axis, and near-bottom samples and in-situ measurements in the water column. Our observations reveal that the off-axis seamounts form near the SEIR axis, and are not associated to off-axis deformation of the ocean floor. They show a general shallowing of the ridge axis from the AAD to the George V TF and the presence of robust axial segments near the transform fault. They allow us to describe the complex evolution of the transform fault system. They also permit to locate new hydrothermal systems along the ridge axis. STORM cruise scientific party: F. Barrere, C. Boulart, G. Ceuleneer, N. Ferreira, B. Hanan, C. Hémond, S. Macleod, M. Maia, A. Maillard, S. Merkuryev, S.H. Park, S. Révillon, E. Ruellan, A. Schohn, S. Watson, and Y.S. Yang.
