Red Sea deep-water ventilation and climate variability during the past 200,000 years (REVENT)

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The Red Sea is a landlocked basin, bordered by the semiarid to arid regions of northeastern Africa and the Arabian Peninsula. The exchange of water masses with the Indian Ocean is restricted to the narrow and shallow strait of Bab al-Mandab and the basin receives major dust input from the borderlands. Consequently, the oceanography and sedimentation processes of the Red Sea respond to even subtle climate and sea-level changes. In the proposed project we want to investigate how the Red Sea overturning circulation and oxygen minimum zone (OMZ) responded to orbital and millennial-scale climate changes during the past 200,000 years and if the oceanographic responses were in phase with hydrological changes and dust fluxes of the borderlands. Specifically, we want to address the hypotheses that 1) the Red Sea deep-water ventilation is linked to global sea-level and is regionally modulated by the influence of the Mediterranean and monsoon climate regimes, 2) millennial-scale climate changes, such as cold and hyper-arid events provoke contemporaneous changes in deep-water circulation and hydrology on the borderlands, 3) the dust fluxes monitor time-transgressive shifts of the African tropical rain belt reflecting thresholds in vegetation and the exposure of dust particles. The sediment archive of the deep Red Sea appears suitable to test these hypotheses since the basin extends SSE-NNW between approximately 12.5° and 30°N and thus is influenced by high- and low-latitude climate regimes. We will investigate three sediment cores along a N-S transect. Benthic foraminiferal stable isotope and pore density records from various parts of the Red Sea will be used for correlation and reconstruction of basin-wide and local changes in deep-water ventilation and OMZ strength. Geochemical records from the same archives will be used to reconstruct the hydrological changes on land, particularly the exposure and deflation of dust particles, but also biogeochemical processes in the Red Sea. The comparison of these proxy records will allow for the evaluation of regional contrasts and time-transgressive nature of humid and dry periods and oceanographic responses. This information is also relevant for the identification and characterization of potential time windows for the migration of anatomically modern humans across North Africa and the Arabian Peninsula into the Mediterranean region and Asia.