A margin transformed: Pure extension to pure translation along the North Falklands Escarpment. Results of Article 76 surveying in the South Atlantic.
The Falklands Plateau comprises an elongate continental block extending eastwards from the Falkland Islands to the Maurice Ewing Bank, 900 kilometres away. While complicated by the transpressive convergence of the Scotia Sea Plate in the South, its margin in the north is characterised by the extreme rectilinearity resulting from its transform separation from the South African craton along the Agulhas Plateau/Ridge system. The translational regime is flanked in the west by the well documented seaward dipping reflector sequences dominating the south Argentine margin, but new and extensive swath bathymetric surveying along the escarpment reveals a transition between the two opening modes characterised by a complex of sheared crustal segments, offset zones, and transform discontinuities. Within this 60 km wide margin parallel zone, en echelon arrays of crustal "tears", many defining a crude tension gash geometry, host submarine elevations, which show varying degrees of rotation in response to the increasing development of shear moment toward the east. We examine the tectonic origin of the ridges in the context of the geological evolution of the margin, their connectivity to the margin, and the comparison with the latest data from the conjugate Agulhas margin off South Africa.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 4200 OCEANOGRAPHY: GENERAL