SEDIMENTARY BASINS OF RONDÔNIA STATE, BRAZIL: RESPONSE TO THE GEOTECTONIC EVOLUTION OF THE AMAZONIC CRATON

AUGUSTO JOSÉ PEDREIRA, RUY BENEDITO CALIARI BAHIA

Resumo


The Precambrian framework of South America comprises the Amazonic and the São Francisco cratons, Neoproterozoic mobile belts surrounding them, other Proterozoic mobile belts and cratonic fragments, scattered throughout Brazil. The Phanerozoic record is represented by Paleozoic-Mesozoic intracratonic basins and the Andean Belt. In the southwestern sector of the Amazonic Craton, the (meta) sedimentary basins of Rondônia State record the geotectonic evolution of that craton: 1) Rondônia Basin, an interior sag basin of Neoproterozoic age, has sandstones and conglomerates deposited by braided rivers in response to continental extension during Rodinia breakup; 2) Parecis Basin, of Paleozoic-Mesozoic age, is a rift-sag basin. The rifts represent reactivation of older structures and are filled by Silurian alluvial fans and Carboniferous glacial sediments. The abortion of the rifts led to subsidence and the sediments of the interior sag basin also record the geotectonic and climatic events of West Gondwana, such as the Permian, Jurassic and Cretaceous deserts, the opening of the Atlantic Ocean and unconformities related to global tectonic events. The Cenozoic Guapore Basin, largely unknown, records neotectonic events related to rotation and translation of the South American plate.

Palavras-chave


Amazonic Craton; Sedimentary basins; Geotectonics; Rondônia State; Brazil.

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