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Evidence of Atmospheric Paleocirculation over the Gulf of Guinea since the Last Glacial Maximum

Published online by Cambridge University Press:  20 January 2017

Anne-Marie Lezine ,
Jean-Pierre Tastet  and
Marcel Leroux
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Abstract

High-resolution pollen and eolian input studies from core KS 84063 in the Gulf of Guinea record the response of the tropical atmospheric circulation to global paleoclimatic events during the last glacial/interglacial transition. Two depositional phases centered around 15,000 and 10,300 yr B.P. are characterized by maximum values of pollen concentration and of eolian activity index (EA1). Pollen spectra record the significant presence of Artemisia and Ephedra of Saharan origin and the scattered occurrence of Podocarpus from Guinean mountain forests; these demonstrate the intensity of the meridional atmospheric circulation over equatorial West Africa during dry periods. The early Holocene humid phase, ca. 8500 yr B.P., is marked by minima in pollen concentrations and EAI. Saharan taxa are absent and, in contrast, Podocarpus reached its highest relative values. This evidence has been interpreted as reflecting a weakening in the continentocean eolian transport and the importance of monsoonal fluxes. Downcore variations in Podocarpus percentages are used to identify the atmospheric circulation patterns over the low latitudes of West Africa during extreme (dry/humid) climatic conditions.

Type
Short paper
Information
Quaternary Research , Volume 41 , Issue 3 , May 1994 , pp. 390 - 395
Copyright
University of Washington

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