Late Quaternary biostratigraphy and paleotemperatures of the Red Sea and the Gulf of Aden based on planktonic foraminifera and pteropods

Abstract

The quantitative distributions of planktonic foraminifera and pteropods were analyzed in seven Red Sea cores and two deep-sea cores from the Gulf of Aden and off Sokotra Island. Biostratigraphic intervals were distin-guished corresponding to oxygen-isotope stages 1–5 in the Red Sea and stages 1–3 in the Gulf of Aden. The faunal assemblages demonstrate that in the Red Sea hydrological conditions changed significantly during the Late Quaternary — especially at the last Glacial maximum, when water exchange at the Bab-el-Mandeb Straits was at a minimum and at the Pleistocene/Holocene boundary. At the end of deglaciation, water-exchange renewal and pluvial conditions resulted in surface salinity decrease and stable stratification, which was followed by a rise in planktonic fauna abundance and stagnation of bottom waters. The more constant composition of rather cold-water (subtropical) faunal assemblages in the Gulf of Aden during the last 40,000–50,000 yrs. points to more stable hydrological parameters and to local upwelling or influx of Arabian upwelling waters. During the last Stadial, mean annual sea-surface temperatures fell by at least 5°C compared to the present in the central part of the Red Sea and by 3.5°C in the western Gulf of Aden.