Lower Jurassic to Early Paleogene Intraplate Contraction in Central Patagonia

Abstract

Breakup and dispersion stages of Gondwana were ruled by crustal extension. In Patagonia, this regime was associated with the opening of extensional basins from the Jurassic onwards, a process that was interrupted by the Andean orogeny. New data generated from the hydrocarbon exploration allowed identifying Jurassic to Eocene contractional deformations, previously not registered in central Patagonia. We summarize in this chapter evidence for five compressional events intercalated with the extensional regime that affected central Patagonia from the Early Jurassic to the Paleogene. These events, denominated ?C1?, ?C2?, ?C3?, ?C4? and ?C5? acted diachronicronously producing tectonic inversion of the Jurassic-Cretaceous depocenters. The first three contractional pulses occurred during the Jurassic while the two remaining were late Lower Cretaceous and early Paleogene. The origin of this compressive activity would be linked to different processes that comprehend from thermal weakening of the crust produced by expansion of the thermal anomaly of Karoo in Mid to Late Jurassic times; the southwards continental drift since the Early Jurassic; the ridge-push generated by the opening of Wedell Sea since Mid Jurassic times; and two mid ocean ridge collisions during the Cretaceous.