Un océan dans le désert, histoire de l’ouverture de la Mer Rouge depuis 30 Ma

Séminaire de Guillaume Baby, post-doctorant en Arabbie Saoudite est accueillit par Delphine Rouby et Dominique Chardon.

Abstract:We characterize the rifting of eastern Red Sea rifted margin and focus on the sediment routing system of the eastern Red Sea margin through two complementary source-to-sink approaches covering the onshore erosional domain (Arabian Shield ), and the offshore depositional domain (syn-rift and post-rift sedimentary depocenters – this study). We estimate accumulated sediment volumes and accumulation rates using a new stratigraphic framework of the eastern Red Sea margin. Accumulated sediment volumes and accumulation rates are low during the syn-rift stage (28-16 Ma) and the transitional stage (16-14 Ma), increase significantly during the early post-rift stage (14-5 Ma), before dropping during the late post-rift stage (5-0 Ma). Accumulated volumes fall within the same order of magnitude than eroded onshore denudation volumes estimated from a landform analysis of the drainage area. From this integrated sedimentary budget, we reconstruct the sediment routing systems of the eastern Red Sea margin and the adjacent Arabian Shield since ~28 Ma. The main drainage divides were located along the active structures during rifting in the north and along the rift axis in the south . High post-rift siliciclastic fluxes are due to the erosion of the rift-related reliefs by scarp retreat and the capture of endorheic basins, combined with local uplifts of the rifted margin. The drop in the fluxes since ~5 Ma, allowing for the renewal of carbonate production in the Red Sea, may be related to an aridification of northeast Africa and Arabia.