Climate swings in the northern Red Sea over the last 150,000 years from εNd and Mg/Ca of marine sediments

Abstract

The εNd and Mg/Ca compositions of terrigenous material from a meridional transect of seven marine sediment cores located between the northern Red Sea and the Gulf of Aqaba, together with modern dust sample compositions, reveal the temporal and spatial changes in precipitation and dust sources over the last ∼150 kyrs, and are further used to discuss the late Quaternary climate history of this region. Two recent glacial periods (Marine Isotopes Stages (MIS) 6 and 2) are characterized by low εNd values associated with a Saharan dust source (∼−12), while Mg/Ca ratios suggest increased transport of dust containing authigenic clays during the last deglacial, which most likely originated from the Arabian Peninsula. By contrast, MIS5e sediments are characterized by an abrupt, basin-wide shift of εNd values toward the local Arabian Nubian Shield end member (∼−2) that are exposed around the Red Sea. This shift stems from intense fluvial events and is coeval with other regional paleo-precipitation records that all point to an extensive northward shift of precipitation from the tropics during MIS5e. Considering model simulations and regional precipitation dynamics, we conclude that although the African summer monsoon probably intensified and extended somewhat northward during MIS5e, it was not the driver of significant precipitation, and the main contribution of precipitation to the northern Red Sea was due to increased frequency and possible intensity of tropical plumes and Red Sea Troughs that triggered massive fluvial floods within the Red Sea catchment. Considering MIS5e as an analogue to a future warmer world, this currently hyperarid region could be exposed over the coming decades to an increased impact of extreme rainfall events, with critical implications for water availability and infrastructure sustainability.