Sediment Dynamics off the East African Continental Margin during the Last Deglaciation and the Holocene: Constrained by Changes in Climate and Sea Level

Abstract

This thesis focused on sediment dynamics on the East African continental margin and their response to paleoclimatic and sea-level changes on a millennial time scale during the last deglaciation and Holocene. High-resolution Holocene sedimentary records (core GeoB12605-3) from the continental shelf off Tanzania indicate that that there has been a shift in the sedimentation regime during the past 10 ka. During the early Holocene, when climate was humid, sediments were dominated by the allochthonous, fine-grained clay minerals transported by river mouth bypassing. In contrast, during the arid, late Holocene, sediments were dominated by the autochthonous, reworked, coarse-grained quartz and feldspars resulting from shoreface bypassing. For the slope environment, the Rufiji turbidite deposits (core GeoB12624-1) are mainly composed of quartz sand. The turbidity currents were most active during the last sea-level transgression and highstand, when a more humid climate prevailed. Thus, it is the climate conditions of the hinterland that form the primary controlling factor in this environment.