Analyse von Bathymetrie und akustischer Rückstreuung verschiedener Fächersonar- und Sedimentecholot-Systeme zur Charakterisierung und Klassifizierung des Meeresbodens am Gakkel-Rücken, Arktischer Ozean

The thesis describes the acquisition, cleaning and visualisation of multibeam data which were collected on RV Polarstern and USCGC Healy during the Arctic Mid-Ocean-Ridge Expedition (AMORE) 2001. The data sets are combined in a high-resolution digital terrain model and a bathymetric chart of the Gakkel Ridge (8W-88E, 82N-87N). In order to process acoustic backscatter from two different sonar systems, Hydrosweep DS-2 and Seabeam 2112, an extensive software package was developed. The angle-normalised and beam pattern corrected backscatter values are compared in five areas. The variation of the backscatter strength is analysed over different rock types, sediment cores and seismogram sections that were measured by the sediment echosounder Parasound. Using angle-invariant backscatter data the Gakkel Ridge is classified in a Western Volcanic Zone (WVZ), a Sparsely Magmatic Zone (SMZ) and an Eastern Volcanic Zone (EVZ). While the basaltic WVZ and EVZ show high backscatter values the backscattering in the SMZ, consisting of mainly peridotites, is rather low. The result of the classification is verified by a second procedure in selected clusters.