Abstract
Northern and eastern Africa were exposed to significantly wetter conditions relative to present during the early Holocene period known as the African Humid Period (AHP), although the latitudinal extent of the northward expansion of the tropical rain belt remains poorly constrained. New records of 230Thxs-normalized accumulation rates in marine sediment cores from the Red Sea and Gulf of Aden are combined with existing records of western Africa dust and terrestrial records across the Sahara Desert, revealing that fluxes of dust transported east from the Sahara decreased by at least 50% during the AHP, due to the development of wetter conditions as far north as ~22°N. These results provide the first quantitative record of sediment and dust accumulation rates in the Red Sea and the Gulf of Aden over the past 20 kyrs and challenge the paradigm of vast vegetative cover across the north and northeastern Sahara Desert during the AHP.
Highlights
Northern and eastern Africa were exposed to significantly wetter conditions relative to present during the early Holocene period known as the African Humid Period (AHP), the latitudinal extent of the northward expansion of the tropical rain belt remains poorly constrained
The sources of the dust were identified using backward trajectory analyses (Supplementary Note 1): dust reaching the northern Red Sea typically originates from northern Libya and Egypt, dust reaching the central Red Sea originates from both Sudan and the Afar region, and dust reaching the Gulf of Aden is delivered from the Horn of Africa
The provenance of the terrigenous fraction of downcore records in the Red Sea, based on their radiogenic isotope composition, confirms that the latter dust sources were active during the late Quaternary and the Holocene[30]
Summary
Northern and eastern Africa were exposed to significantly wetter conditions relative to present during the early Holocene period known as the African Humid Period (AHP), the latitudinal extent of the northward expansion of the tropical rain belt remains poorly constrained. These carbonate deposits are further characterized by distinctly light oxygen isotopes, which were interpreted to reflect a northward expansion of summer African monsoon rains that brought Atlantic Ocean moisture to the Desert[29] rather than a proximal source in the Mediterranean Sea. Here, we focus on the northeastern part of Africa and present new records of 230Thxs-normalized dust accumulation rates
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