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Type: Journal article
Title: Stable carbon and oxygen isotopic composition of early-Holocene gastropods from Wadi Mansurab, north-central Sudan
Author: Ayliffe, Damien
Williams, Martin Anthony J.
Sheldon, Fran
Citation: Holocene, 1996; 6(2):157-169
Issue Date: 1996
ISSN: 1477-0911
School/Discipline: Geographical and Environmental Studies
Mawson Graduate Centre of Environmental Studies
Statement of
Damien Ayliffe, Martin A.J. Williams and Fran Sheldon
Abstract: The 8500- to 7000-year-old shell-bearing sediments in shallow claypans near Wadi Mansurab in north-central Sudan appear to reflect a widespread and much wetter period in northeast Africa. Stable carbon and oxygen isotope analysis of the Wadi Mansurab gastropods reveals that the shell carbonate is highly depleted in ¹³C and ¹⁸O. The highly depleted oxygen isotopic composition is indicative of rainfall derived from a distant oceanic source. The highly negative nature of the oxygen isotopes indicates that the region had significantly less evaporation than today while the extreme variability in isotopic composition (up to 6-7‰ PDB) is consist ent with a seasonal rainfall regime, characterized by a high degree of inter-annual variability. The dominance of semi-aquatic and swamp-dwelling gastropods over truly aquatic species implies that the region was probably a seasonally flooded grassplain similar to the toich-lands of south-central Sudan today. Our data support the inference that towards 8500-7000 BP there was a stronger southwest monsoon and an associated northward shift in the summer rainfall zone, which caused the Wadi Mansurab region in north-central Sudan to be season ally flooded during a wetter and possibly cooler period with lower rates of evapotranspiration. From 8500 to 7000 BP, lake levels were high elsewhere in northern Africa, suggesting a regionally wetter climate at that time.
Keywords: Early Holocene; stable isotopes; 13C; 18O; carbon; oxygen; freshwater mollusca; palaeoenvironments; climatic change; Sudan; north-east Africa
Rights: © Arnold 1996
DOI: 10.1177/095968369600600203
Appears in Collections:Geography, Environment and Population publications

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