Koordinatorantrag zur METEOR-Reise 75

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La Reunion hotspot setting is highly favourable to study mechanisms involved in the functioning of a deep mantle plume and in the evolution of such an oceanic volcanic system. Dismantling of volcanic edifices due to flank destabilizations and erosion is now recognized as a major component of their long-term evolution. It largely contributes to the construction of submarine slopes of such islands. However, these mechanisms remain largely unknown, hi the case of La Reunion, the aim of the proposed cruise ERODER is to better understand, and to quantify, the processes and the dynamics of the transfer of sediments and epiclastic materials on the submarine slopes of a large intraplate oceanic volcanic system, and to evaluate their importance in the present and past evolution of the volcanic edifice itself. ERODER is based on a detailed geophysical survey (swath bathymetry and backscatter data, gravity. 3.5-Khz sediment penetrator) of the upper part of the edifice and on the use of direct or indirect high resolution observation tools (e.g., side scan sonar - SAR) on precise targets of the submarine part of the island. The proposed work is multidisciplinary, interesting both sedimentary and volcano-structural aspects, in order to specify the processes of the evolution of the submarine flanks of the island and to establish the relationships with the subaerial structures and processes. M75/1B: In order to obtain detailed observations on the year to year variability of the flow in and through the Mozambique Channel an array of moorings with current meters (and one sediment trap) has been deployed at the narrowest section of the Channel for a period of at least 5 years. The first deployment was done in November 2003 and servicing of the moorings has been done in February 2005 and March 2006. The first purpose of the cruise in January 2008 is to recover and redeploy the moorings in the Mozambique Channel after the data have been retrieved and the instruments have been serviced. The second purpose is to obtain hydrographic observations and samples of the seafloor (from multi-coring) along the section where the moorings are deployed. The observational methods to be applied during the hydrographic survey will be the lowering of a CTD and rosette sampler with 101 sampler, as well as an LADCP instrument to determine the vertical velocity profile. A ship-mounted ADCP will be used to determine the surface (0-500m) velocity structure en route, while a thermo-salinograph will monitor the sea surface salinity and temperature. The research is part of the Dutch contribution to the international CLIVAR (CLImate VARiability) programme which is part of the WCRP (World Climate Research Program).