Dynamics of North African Humid Periods of the last 130 kyr

• Applicants: Professor Dr. Werner Ehrmann; Professor Dr. Gerhard Schmiedl
• Subject Area: Palaeontology
• Term: from 2014 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 262219341

Geological data and model simulations document repeated African Humid Periods during the late Quaternary. Each of them spans ca. 10 kyr and corresponds to a much shorter interval of sapropel formation in the deep Eastern Mediterranean Sea (EMS). Because only few detailed geological records are available and numerical circulation models do not draw a uniform picture, there is still a debate regarding the dynamics of the humid periods, especially the nature of the landscape evolution, the asymmetry between West and East African records, the dynamics during onset and termination of humid periods, and possible biophysical feedbacks between climate and vegetation.In our proposed study we plan to approach these open questions from a distal perspective by reconstructing the intensity and dynamics of dust fluxes from North Africa into the EMS. We will achieve this by producing high-resolution data sets from three sediment cores recovered from key positions in the EMS. The cores contain sediments of the last 130 kyr including sapropel layers S1 to S5 and the corresponding humid periods. Core GeoTü SL110 was retrieved from the Nile River discharge plume in the SE Levantine Sea, close to the coast of Israel, and should document changes in the monsoon-driven riverine sediment input. Core SL99 comes from the SW Levantine Sea, close to the North African coast off Libya. It should be primarily influenced by dust fluxes from the central and eastern Sahara, and should record the hydrological history of that region. Core SL71 comes from the Ionian Sea, SW of Crete. Our preliminary study shows that in this core we can distinguish between climatic signals from the north and the south.We want to investigate especially the interplay of solar insolation, monsoon activity, precipitation, vegetation cover, river runoff, wind erosion and aeolian transport. We are most interested in the timing of the African Humid Periods, on their gradual versus abrupt onsets and terminations and the relation between aridification/dust transport and precipitation/river discharge. To this end, we intend to apply different sedimentological and geochemical proxies for investigating processes involved in the transfer of climatic signals from the central and eastern part of North Africa to the EMS. Suitable proxies are clay minerals, grain sizes and major and trace elements. Furthermore we want to study the species composition and microhabitat structure of the benthic foraminiferal fauna in order to assess the fertilization potential of Saharan dust on the marine ecosystem of the EMS.

• DFG Programme: Research Grants