From platform top to adjacent deep sea: new source-to-sink insights into carbonate sediment production and transfer in the SW Indian Ocean 2 (Glorieuses archipelago)

International audience18 19 Over the past ten years, a huge amount of source-to-sink studies have aimed to unravel the 20 tectonic, climatic and other processes that shape the landscape from mountains to the deep 21 ocean. Interestingly, these studies have been mainly dedicated to siliciclastic or mixed 22 systems, for which the connection between drainage basins, continental shelves, slope and 23 basin environments are often well constrained. Here we present a study focusing on a source-24 to-sink study dedicated to a pure carbonate system, located in the SW Indian Ocean 25 (Glorieuses archipelago). Extensive field sampling and geophysical acquisition across the 26 carbonate platform have allowed us to estimate the composition, the lateral variability, and 27 volumes of neritic sands deposited on the platform top. Additional seismic and bathymetric 28 surveys across the platform interior illustrate the presence of plurimetric sandy bodies 29 deposited along the leeward platform edge, corresponding to the export of carbonate 30 sediments from the platform top toward the platform edge, under the influence of dominant 31 currents and wind-driven processes. High-resolution seismic, bathymetric data and sediment 32 cores acquired along slope and basin adjacent to the carbonate platform highlight the presence 33 of channel-levee complexes and turbiditic lobes, which have accumulated on top of a 250m-34 thick sedimentary basin at 2000-3400 m water depth. Our study points out that a half of 35 carbonate sands and aragonitic mud have been shed from the platform top to the adjacent 36 basin during the Holocene. We also demonstrate that this routing system was active at least 37 through the last three glacial/interglacial cycles. This study has important consequences for 38 our understanding of carbonate sedimentation processes occurring in the vicinity of isolated 39 carbonate platforms, and contributes to a first quantification of a carbonate source-to-sink 40 system. 41 4