Holocene Paleoclimates in Northwestern Sudan: Stable Isotope Studies on Molluscs

In four paleolakes in northwestern Sudan, mollusk shells were collected, and isotopic ratios, along with bulk sedimentary carbonate deposits, were used to examine patterns of precipitation and post-precipitation evaporation. The carbon isotope ratios of the shells collected at various stratigraphic...

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Bibliographic Details
Published in:Global and planetary change 2000-11, Vol.26 (1), p.1-1
Main Authors: Abell, Paul I, Hoelzmann, Philipp
Format: Article
Language:English
Online Access:Get full text
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Summary:In four paleolakes in northwestern Sudan, mollusk shells were collected, and isotopic ratios, along with bulk sedimentary carbonate deposits, were used to examine patterns of precipitation and post-precipitation evaporation. The carbon isotope ratios of the shells collected at various stratigraphic levels paralleled the oxygen isotope ratios. Results are presented separately for each lake. Based on the more negative isotope ratios, the precipitation feeding the lakes was determined to have been of a much lighter isotopic composition than would have been predicted otherwise. While the oxygen isotope ratios of the mollusks and bulk carbonates suggested that the rainfall was highly depleted in oxygen isotope ratios during the last climatic optimum between 9000 and 6000 yr BP, there was subsequent modification of the ratios by evaporative fractionation during the dry intervals in the year, especially in the lakes furthest north.
ISSN:0921-8181