Falkland Plateau evolution and a mobile southernmost South America

Assessment of southwest Gondwana break-up and its implications for regional hydrocarbon prospectivity must now take into account the origin of the southeast margin of the Falkland Islands as a volcanic rifted continental margin, and of the floor of the major part of the Falkland Plateau Basin as elevated oceanic crust. A reconstruction of the Falkland Plateau against southern Africa shows a southward extensional widening of the Outeniqua Basin across the line of the Falkland-Agulhas Fracture Zone, changing from stretched continental to oceanic crustal structure. Such a model for Outeniqua Basin opening, and the independent westward and clockwise rotation of the Falkland Islands block, suggests that southernmost South America was also a collection of microplates moving independently within a generally extensional environment in the Late Triassic-Early Jurassic. This is incompatible with assumptions of a rigid southernmost South America over this time, and a dominant role for a continuous dextral strike-slip Gastre Fault.

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