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Seismic Survey of the Antarctic Peninsula Pacific Margin: Results of the 1989-92 Cruises of the RN OGS-EXPLORA

M. Rebesco, A. Camerlenghi and G. Brancolini

Abstract: 

This paper presents a preliminary interpretation of the multichannel seismic reflection data set collected by the Osservatorio Geofisico Sperimentale (OGS) within the Programma Nazionale di Ricerche in Antartide (PNRA) on the Antarctic Peninsula Pacific Margin south of the Hero Fracture Zone. The profiles have been correlated with those collected by the British Antarctic Survey in the northeastern part of the margin. We identified four seismic sequences on the continental shelf and slope, and previously unknown large sedimentary bodies on the continental rise. We describe the data set on three different settings of the margin: continental shelf, outer shelf and slope, and continental rise. We outline the two principal results, which correspond to thematic objectives of the Antarctic Offshore Acoustic Stratigraphy (ANTOSTRAT) program: 1. The identification of a prograding wedge of sediments on the continental shelf and slope with different characteristics along the margin supports the observation that the sedimentary regime of the Antarctic Peninsula Pacific Margin is controlled by synchronous glacial/interglacial processes and diachronous ridge crest-trench collisions. 2. The large sedimentary bodies identified on the continental rise show indications of bottom-current control on the depositional processes affecting the margin. External shape and internal characteristics, together with general considerations on deep circulation in the Southern Ocean, allow us to interpret these bodies as sediment drifts.