Search

On the research cruise ARK-XXVIII/4 with the RV Polarstern from the 5th of August to the 8th of October 2014 an extraordinary see ice free area was detected over the Lomonosov Ridge south of 85°N what granted a very successful aquisition of multichannel seismic reection data of 3084 km in length. Two aims of collecting these data, among others, were to provide an appropriate database for an IODP drilling proposal, and to enhance knowledge of sedimentary and tectonic processes in the area. In this thesis, the southern part of the collected seismic dataset is processed and interpreted. The seismic multichannel data were acquired with a 3000 m long streamer and an airgun cluster of 4 G-Guns. The dataset consists of two seismic profiles across the Lomonosov Ridge and its adjacent basins and a detailed network of profiles around the proposed drilling sites, LR-1A and LR-2A. The seismic data were processed with an emphasis on velocity analysis of those drilling sites and the suppression of multiple reflections. The seismic sections are dominated by an High-Amplitude Reflector Sequence (HARS) that persists across the entire profiles and that separates the flat-lying well-stratified upper unit of Cenozoic age from the lower Mesozoic sediment sequences. The top of the reflector sequence, probably represents the transition from an isolated stagnant shallow-water environment to a deep ocean with active hydrodynamics and correlates to the opening of the Fram Strait. Thus, it shows an age of latest Oligocene/Early Miocene. The base of the unconformity marks the break-up of the Lomonosov Ridge from the Siberian/Barents shelves between 58-56 Ma. A ray tracing program was applied on the seismic reection data of the two drilling sites where a drop of interval velocity in the HARS was detected. Thus, one of the main achievements of this thesis is the calculated decrease of drilling depth at LR-1A and LR-2A which allows to reconsider the main goals of the next Arctic Coring Expedition