Structure of the South Powell ridge (NE Antarctic peninsula): new clues for changing tectonic regimes near the Scotia/Antarctica plate boundary

The structure of the South Powell Ridge (SPR), separating the Late Cenozoic ocean-floored Powell Basin and the Mesozoic Weddell Sea domain, is reveale d by multichannel seismic data. The SPR appears as a basement high, bounded northward by transtensional faults and by normal and major reverse faults to the south. These margin features seem to be linked to the Powell Basin s outhern strike-slip margin and to the Jane Are paleotrench, respectively. W e suggest the ridge evolved from the Antarctic Peninsula passive margin to become the deformational front of the Scotia/Antarctica Plate boundary, lat er being welded to the Antarctic Plate.