Mapping
Scientist on board RV SONNE observing the incoming data from the Kongsberg multi-beam echo sounder EM122 (right screen) while searching for potential dredge sites utilizing the 3D visualization of the QPS software Fledermaus (left screen)
A prerequisite for understanding and interpreting underwater geological structures is the best possible mapping of the underwater landscape. The availability of such high-resolution bathymetric data is also essential for rock sampling. In general, we utilize the research vessels鈥� own multi-beam echo sounder systems (e.g., Kongsberg Maritime EM122, EM710) to obtain this data and for continuous mapping of the seafloor. The accuracy of the depth data obtained from these systems is critically dependent upon the use of a correct sound velocity profile of the water column. Sound profiles were therefore determined by using the ships own CTD probe. For a first assessment of the data and for the selection of dredge positions the QPS software Fledermaus is usually used allowing 3D visualization. The subsequent data cleaning is then accomplished by the QPS Qimera software.
Sampling
The main sampling method of submarine magmatic structures used by the Petrology/Geochemistry of the Seafloor group (MUHS-P) is dredging. For this task, we own eight heavy chain-bag dredges that we have specially developed/refined for this purpose (plus two older models). During deployment, the devices are pulled up a submarine slope for a short distance, using the winch of a respective research vessel, so that rocks are collected and stored in the chain bag until the dredge has bean hoisted back on deck. Compared to other methods, this is still the most effective, quickest and cheapest way of gaining a good (first) overview of the nature of the underwater structures.
Chain bag dredge deployed from RV METEOE during expedition M191 in the Mediterranean Sea.
