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A new perspective on the geology of the FalklandIMalvinas Pl ateau (South Atlantic) is derived from a detailed synthesis of 14,000 km of mainly unpublished slngle-channel and multichannel seismic data, aided by redge-haul descri ptions and DSDP data. The Plateau is II foundered cornplex of continental blocks that were differentially rifted during the opening of the South Atlant ic in lhe Midd le Jurassic to Early Cretaceous, Up to 7 km of synrift, transitional, and hemipelagic sediments have been deposited since the Middle Jurassic, largely under the control of a northem marginal fracture ridge. Three major structural lineations outline basemenl geometry, They are: 1. a NE-SW tectonic trend marking the eastem edge of the Plateau; 2. the Falkland Escarpmenl marginal fracture ridge lo the north and nearby grabens thal are parallel or subparallel to the approximately E-W Falkland Fracture Zone; and 3. the westem edge of the Maurice Ewing Bank running NW-SE thal is related lo extensive rifting and volcanic activity in the central Falkland Basin, The complicated geometries of these structural trends are related lo triple-junction tectonics when the South American, African, and Antarctic blocks moved apart in the Late JurassicJEarly Cretaceous. We estimate that the Plateau had been lengthened by ai least 400 km in an east-west direction, before the initiation of drift at about anomaly MIO lime. From the acoustic stratigraphy we have defined four widespread depositional sequences. Three of these have been sampled by DSDP drilling and their bounding unconfonnities are interpreted to have resulted from: 1. an early Paleozoic pediplanation; 2. a post-rift erosional truncation; and 3. erosion by ocean currents that preceded the establishment of the Antarctic Circumpolar Current near the time of the Cretaceousffertiary boundary. Our seismic profiles reveal that in the early Paleogene, migrating sediment drift deposits several hundreds of meters thick were deposited over the whole Plateau. A fourth depositional sequence remains unsampled by drilling. It is bounded below by an intra-Cretaceous unconfonnity that originated from ocean current activity and its top by the above mentioned crr erosional surface. Six isopach sediment and basement structure maps which succinctly display the geometries of these sedimentary units are included. ReSUMO ESTRATIGRAFIA SíSMICA E EVOLUÇÃO TECTÓNICA DO PLATÓ FALKLAND/MALVINAS. Uma nova perspectiva da geologia do Platô Falk1andlMalvinas (Atlântico Sul) deriva de uma síntese detalhada de 14.000 km de sísmica de reflexão mono e multicanais, na sua maioria não publicados, em conjunto com descrições de rochas e de perfurações do DSDP. O Platô é um complexo de blocos continentais submersos que foram diferencialmente estendidos durante a abertura do Atlântico Sul no Mesojurãssico-Eocretâceo. Um máximo de 7 km de sedimentos sinrifte, transicionais e hemipelâgicos foram depositados desde o Mesojurãssico, largamente sob o controle estrutural de uma cadeia marginal de zona de fratura. A geometria do emba...

Abstract. Recem Ocean Drilling Program sampling of the Ctte d'Ivoire-Ghana margin of WestAfrica provides for the first time the opportunity to study the development of a marginal ridge that formed along a sheared passive margin adjacent to the continent-ocean transition after the end of intmcontinemal wrenching. We model its evolution using a two dimensional flexural backstripping technique. The model is constrained by existing seismic refraction and reflection data on the crustal structure and stratigraphy and paleobathymetric evidence from the cores.