Coupled sea-level and hydroclimatic controls on the southern Red Sea sedimentation during the past 30 ka

Abstract

Sedimentation in the Red Sea basin is governed by the complex interplay between regional atmospheric circulation, precipitation patterns, and sea level fluctuations, which altogether exert a profound control on the detrital and biogenic components of the sedimentary record. To gain a comprehensive understanding of these controls on the southern Red Sea sedimentation over the past 30 ka, we here combine high-resolution bulk geochemical and mineralogical data with detrital grain-size distributions and plant-wax biomarkers at a sub-centennial average temporal resolution. Our proxies reveal that the sedimentary record is characterised by two distinct depositional regimes of detrital and marine origin. The pronounced shift from the detrital-dominated (ca. 30–14.6 kyr) to the marine-dominated phase (ca. 14.6–0.8 kyr) coincides with the end of Heinrich Event 1 and the rapid sea-level rise associated with Meltwater Pulse 1a. Flooding of the shelf during deglacial sea-level rise increased the distance between the core site and the respective shoreline, and partially controlled the delivery of detrital material to the site. Shifts in detrital grain-size distribution and mineralogical composition indicate a reduction in regional continental aridity and potentially weaker wind circulation with the onset of Greenland Interstadial-1, while the reestablishment of water-mass exchange with the Gulf of Aden from ca. 15 ka onwards led to a marine productivity surge at our study area. An increase of fine-grained fluvial material and terrestrial n-alkanes between ca. 16 and 8 ka points to the establishment of more pluvial conditions and the activation of local wadi runoff during the African Humid Period. Finally, the subtle but steady increase of detrital input from ca. 5 ka onwards suggests the re-establishment of continental aridity during the late Holocene.