Benjamin Baasch

PhD project:

Electromagnetic Imaging of the marine subsurface: A novel approach to assess sediment patterns and dynamics on clastic shelf systems

Clastic shelf systems, as major sediment sources and sinks, build the critical interface between the continent and the ocean on the sediment pathway. Surficial sediments in these areas are subjected to high dynamic processes driven by climatic, hydrodynamic or anthropogenic influences and therefore provide information about the recent and paleo environmental situation.

Classical sedimentological investigations based on surface sampling and sediment coring often do not provide sufficiently high spatial resolution. A novel approach to overcome this limitation is the electromagnetic (EM) imaging of the marine subsurface. The EM data provides information about the magnetic susceptibility and electric conductivity of the bottom sediments in sub-meter resolution. Magnetic susceptibility offer valuable clues to the mineral composition of the sediments and can particularly be used as a proxy for fine-grained terrigenous clay/silt content, diagenetically forced magnetite depletion, anthropogenic metallic contaminants and metal accumulation. Electric conductivity is mainly controlled by the pore fluid and is therefore primarily considered as a measure of porosity and grain-size distribution. The results obtained from the EM measurements can be merged and jointly interpreted with other high-resolution geophysical and oceanographic data sets, such as derived from acoustic backscatter, conductivity-temperature-depth (CTD) and turbidity measurements, and calibrated with laboratory data from surface samples.

In this PhD project I will mainly investigate data from the Meteor cruise M84/4b, which was acquired with the new benthos EM-profiler MARUM NERIDIS III on the NW Iberian Shelf, one of the three key areas of MARUM research project ‘Sediment Dynamics 2‘ (SD2), representing a non-glaciated clastic shelf system.

Research Theme: B "Ocean and Seafloor"