EARLY TECTONIC EXTENSION BETWEEN THE AGULHAS BANK AND THE FALKLAND PLATEAU DUE TO THE ROTATION OF THE LAFONIA MICROPLATE

Along the Southeast African continental margin, a deep sedimentary bas in and marginal ridge bordering the Agulhas Fracture Zone formed coeva lly with South American counterparts underlying the Falkland Plateau. Extension in both the Southern Outeniqua and the Falkland basin is rel ated to large-angle (approximately 100-degrees) rotation of the Lafoni a (Falkland Islands) block in Middle-Late Jurassic times, during attem pted propagation of the proto-Indian Ocean across the active circum-Pa cific margin of Gondwanaland. In the Early Cretaceous, the Jurassic mi croplate boundaries were partly reactivated, and partly transected by a right-lateral shear along the approximately 1200 km long Falkland-Ag ulhas transform fault. Preceded by substantial vorticity of the surrou nding crustal blocks, this boundary segment separating the South Ameri can and African plates was probably generated by complex geodynamic in teractions between oceanic plate subduction, continental to back-arc r ift propagation, and the impingement of deep mantle plumes on the lith osphere.