Changes in mesophotic carbonate-platform export across the end of the last glacial cycle (Saya de Malha Bank, western Indian Ocean)

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Abstract
The export of neritic material from the top of carbonate platforms is a key process in the construction of their slopes. However, our knowledge of the supply pattern of materials from platforms is dominantly based on platforms lying in the euphotic zone during the present sea-level highstand. This is a somewhat biased perspective as through geological time not all platforms were euphotic. The Saya de Malha Bank in the Mascarene Plateau is an example of a modern mesotrophic carbonate platform and as such its flooding and export patterns differ from those of euphotic ones. Using cores collected on the western slope of the Saya de Malha Bank, we explored the export patterns of the platform since the Last Glacial Maximum. Material on the platform edge is winnowed and transported to the slope by multiple possible processes. The material on the platform is a combination of high and low Mg calcite as well as high and low Sr aragonite, integrating pelagic and neritic sources. The ratio of these constitutes varies over time with variation in the platform production capability as it flooded and drowned during the Holocene transgression. The material from the platform is transported in both confined flows, mainly during lowstands, and unconfined flows, mainly during late transgression and early highstand. In the present state of the highstand, supply may have diminished, leading to erosion of the canyon shoulders.

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