Seismic stratigraphy and tectonic evolution of the Flakland/Malvinas Plateau

Abstract

A new perspective on the geology of the Falkland/Malvinas Plateau (South Atlantic) is derived from a detailed synthesis of 14,000 km of mainly unpublished single-channel and multichannel seismic data, aided by redge-haul descriptions and DSDP data. The Plateau is a foundered complex of continental blocks that were differentially rifted during the opening of the South Atlantic in the Middle 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 northern marginal fracture ridge. Three major structural lineations outline basement geometry. They are: 1) a NE-SW tectonic trend marking the eastern edge of the Plateau; 2) the Falkland Escarpment marginal fracture ridge to the north and nearby grabens that are parallel or subparallel to the approximately E-W Falkland Fracture Zone; and 3) the western edge of the Maurice Ewing Bank running NW-SE that is related to extensive rifting and volcanic activity in the central Falkland Basin. The complicated geometrics of these structural trends are related to triple-junction tectonics when the South American, African, and Antarctic blocks moved apart in the Late Jurassic/Early Cretaceous. Keyword: Reprints. (KR)