Gamma spectrometry for chronology of recent sediments Tracing human induced climate change in NW Africa

Gamma spectroscopy was used for determination of radionuclides in sediment cores from the continental shelf off NW Africa to provide age control of the sediment record used for a study of aridification of the Sahel zone. Pb, Ra and Cs were measured in the upper part of a gravity core and the associated multicorer and used for aligning these cores. This provided information about the amount of sediment loss due to the sampling procedure in the upper part of the gravity core. The age model based on the matched profiles extended to 140 years B.P. and the rest of the gravity core was dated by C. The Pb age allowed the estimation of the local radiocarbon reservoir age. Application of Pb and Cs chronology helps significantly to extend paleoclimatic proxy data into the Anthropocene, thereby allowing to compare human induced climate change with natural climate variability.