Dr. Janna Just

Archived Page This web page has not been updated since the former colleague left MARUM.

 

Marine terrigenous sediments accumulated at continental margins are often used as archives for terrestrial paleoenvironmental conditions. To infer about the weathering regime on land, elemental ratios and the magnetic mineralogy are used, which depend on conditions during soil formation. Precipitation and vegetation reconstructions can be carried out on organic proxies, i.e., the isotopic composition of plant-waxes. Within large river basins the source area of the sediments may shift. Additionally, sediments that are transported by wind or rivers are also influenced by transport, e.g., gravitational sorting. It is therefore essential to evaluate the processes affecting the record of terrigenous fluxes from source-to-sink.

In my current project I am working on fluvial sediments deposited off the Zambezi River (Mozambique) over the past 20 ka. It was observed that during the late glacial and Holocene significant changes in precipitation occurred in the hinterland. It is however uncertain, if theses variations correspond to environmental change in the entire river basin, reflect shifts of a source area within the basin are due to changing transport conditions. By using a multi-proxy end-member unmixing approach, we aim for reconstructing changing multi-parameter properties of the fluvial material. Each of the considered characteristics is influenced by conditions in the source areas of the fluvial sediments (e.g., weathering, precipitation) or transport processes.
The joint characterization of changing the multi-parameter properties should enlighten the paleoclimatic development of the Zambezi river basin – eventually on a sub-basin scale – and shifts of source areas for the terrigenous fraction within the basin. Additionally, the application of the respective proxies of terrestrial environmental change will be tested.