Glacial to Holocene Hydroclimate in Western Africa: Insights from Organic and Major-Element Geochemistry of Hemipelagic Atlantic Ocean Sediments

Abstract

The distribution of rainfall in Africa during past climates is not well constrained. In particular, many existing proxy reconstructions in Africa are not consistent with North-South migrations of the rainbelt that are seen in other regions. In this thesis, rainfall distribution across western Africa is investigated at key climate states of the past using a transect of hemipelagic marine sediment cores spanning from 21°N to 23°S in the eastern Atlantic Ocean. Stable carbon and hydrogen isotopes of plant leaf wax n-alkanes are interpreted as proxies for vegetation type and the hydrogen isotopic composition of meteoric water, respectively. In semi-arid regions, dust emissions are strongly linked to hydroclimate. As such, major element geochemistry from 4 continuous sediment core records (21°N-9°N) is also investigated in order to reconstruct dust vs river input from West Africa over the last 45kyrs.