Global to regional Holocene climate changes and events recorded in a near-slope deep sea brine-pool sediments of the NE Red Sea

Abstract

Marine climate archives in Red Sea sediments have the great potential to improve our understanding of mankind’s dispersal out of Africa. However, cores from deep sea sediments are often greatly disturbed by bioturbation reducing the resolution of recorded climate events. We report geochemical and geophysical data from a 244 cm long sediment core collected from a recently discovered deep sea brine pool near the Arabian slope and the Al Wajh carbonate platform. The analysis of the high-resolution climate archive preserved in the undisturbed sediments of the brine pool provide excellent correlations to numerous known historical events in the last 6.5 ka, and indicate the great potential of brine pool sediments to provide further insights into climate changes and human civilization development within the African-Arabian dessert belt. The recovered marine sediment core from a brine pool was therefore investigated to test its reliability for in-depth Holocene climate studies. The brine-filled depression (>190 PSU; 25 m thick) is located 25 km south of the Al Wajh carbonate platform in 640 m water depths. It is bounded by a salt extrusion in the northwest and a steep shallow water reef in the east. The undisturbed dark-olive coloured sediment succession are carbonate-dominated, devoid of bioturbation, and rich in TOC indicating an anoxic environment. The established stratigraphy via five radiocarbon dates of (planktic foraminifera. T.sacculifer and O. universa) resulted in high sedimentation rates ranging from 30.22 to 50.6 cm/ka. The integration of geochemical (e.g., isotope data, XRF) and geophysical data (e.g., magnetic susceptibility, spectrophotometer reflectance) revealed the recording of dozens of prominent climate periods (e.g., Roman Climate Optimum, Little Ice Age), changes (e.g., Mid-Holocene Highstand), and historical events (e.g., collapse of Late Uruk and Akkadian Empire) since the Mid-Holocene. In addition, the data analyses suggest that even periods of increased ENSO activity are recorded within the brine pool sediments of the Red Sea. The outcome of this study highlights the potential of anoxic brine pool sediments as a unique and important high-resolution climate archive and the urgent need to further in-depth studies.