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ABSTRACT: Correlations of Onshore/Offshore Structure from a Combined AVHRR/Geosat Altimeter Image of the Antarctic Plate

I. W. D. Dalziel, D. T. Sandwell, J. Y. Royer, L. A. Lawver

Data collected by the Advanced Very High Resolution Radiometer (AVHRR) aboard Nimbus-X and the satellite altimeter aboard Geosat have provided an extraordinary view of the Antarctic continent and the surrounding seafloor. To examine the relationship between onshore and offshore structure, we have merged an AVHRR mosaic image produced by the British National Remote Sensing Centre with a geoid image derived from two years of Geosat altimetry. We averaged 44 repeat cycles of Geosat data to improve the accuracy, resolution, and coverage of the marine geoid, especially in areas usually obscured by year-round ice. In addition to constructing the geoid image, the Geosat data were combined with available shipboard bathymetric data and magnetic anomaly identifications to construct a tectonic element chart of the Southern Ocean. The major tectonic elements include several large age-offset fracture zones that place tight constraints on the breakup of Gondwana. In many cases, onshore extensions of these major fracture zones correlate with prominent continental structures. For example, the Tasman FZ extends from the western edge of Tasmania for 2500 km across the southern Indian Ocean and terminates along the eastern edge of George V Basin. Onshore, this prominent lineation continues along the edge of the Trans-Antarctic Mountains in Victoria Land, Antarctica. Similarly, the Udintsev FZ extends from the northern edge of the Chatham Rise for 4500 km across the South Pacific to a point north of Thurston I., where it fades out. The onshore extension of the Udintsev FZ ma mark a major tectonic and physiographic boundary between the Weddellia (Antarctic Peninsula, Ellsworth-Whitmore, and Thurston Island) and Marie Byrd Land crustal blocks of West Antarctica. Other prominent onshore/offshore correlations include the continuation of the Queen Fabiola Mountains as the Gunnerus Ridge (Antarctic margin, 33°E) and the continuation of the Lambert-Amery aulacogen seaward onto the continental margin.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990