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1 Alfred Wegener Institute for Polar and Marine Research, Columbusstrasse, 27568 Bremerhaven, Germany
2 Renard Center of Marine Geology, Rijksuniversiteit Gent, Krijgslaan 281, 9000 Gent Belgium
The geodynamic understanding of the Gondwana break-up between Africa, South America and Antarctica depends strongly upon the quality and coverage of geological and geophysical data. In this area, the tectonics of the Weddell Sea embayment plays an important role in constraining plate movements during the early opening of the Southern Ocean. Geophysical data collected in 1990 and 1992, including multichannel seismic data and gravity measurements as well as altimeter data from ERS-1, give new insights into the shape and structure of the continental margin off East Antarctica between 10°W and 30°W. With the seismic network a new geological structure, the Polarstern Bank, could be mapped at 71°15'S, 25°W. We interpret the feature to consist of several seamounts, striking almost N-S. The location of this prominent structure between the Andenes and Explora escarpments makes the presence of a continent-ocean boundary in this area as proposed by other models unlikely. Our interpretation is supported by all data sets presented in this paper. Based on our results, the two escarpments must have different geological origins and may also have different ages. The data indicate that the continent-ocean boundary runs parallel to the present coastline of the East Antarctic marked by a pronounced positive free air gravity anomaly and a positive magnetic anomaly.
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This 250-word extract was created in the absence of an abstract.
