Processed seismic data of Cruise ANTVIII/6 1990

The POLARSTERN cruise ANTVIII/6 from 14. March to 30. April 1990 incorporated an integrated geophysical reconnaissance survey consisting of multichannel seismic measurements in parallel with gravimetric and magnetic measurements. The survey covered the plateaus Maud Rise, Astrid Ridge and Gunnerus Ridge off Queen Maud Land and the oceanic crust in their vicinity. Severe ice and weather conditions allowed seismic work only on the Gunnerus Ridge and on the oceanic crust. Together with previous BGR lines on the Astrid Ridge and the Maud Rise the new data improve considerably the understanding of the area. The main results are: 1. The oldest identified sea-floor spreading anomaly was M11 before the cruise, now it is M24. Thus spreading has begun not only 135 mill. years B.P., but at least 160 mill. years B.P. 2. The Gunnerus Ridge is strongly asymmetric. The mainly weak magnetic anomalies indicate that in contrast to the Astrid Ridge volcanism was not important during its development. 3. The magnetic anomalies are much stronger on the Astrid Ridge and west of it than east of the Astrid Ridge and on the Gunnerus Ridge. 4. The roughness of the basement surface of the oceanic crust varies in a wide range.