ESTRATIGRAFIA E SEDIMENTOLOGIA DO PROTEROZÓICO MÉDIO E SUPERIOR DA REGIÃO SUDESTE DO CRÁTON AMAZÔNICO

Abstract

STRATIGRAPHY A>TOSEDIMENTOLOGY OF THE MIDDLE AND LATE PROTEROZOIC IN THE SOUTHEAST OF THE AMAZONIAN CRATON. The southeastern part of the Amazonian Craton is made up of Archean and Lower Proterozoic sequences including gneiss, greenstone belts and a huge granitic suite. During the Middle Proterozoic this craton was affected by an exteasional regime, during which fult zones of the cratonic basement were reactivated. Basins formed during this episode were nUed byte sediments of the Aguapei, Sunsás and Huanchaca groups. These sedimente are interpreted as the product of deposition as a platform cover, with extensive shallow marine by-passing to deeper marine deposition ends with fluvial sediments. In the Sunsás and Aguapef belt these middle Proterozoic sediments were affected by the Sonsas Orogeny, whereas in the Huanchaca, Santa Barbara and Rio Branco regions, they are spared of the deformation. Late Proterozoic sediments and metasediments are present along the trasition zone between the Amazonian Craton ande the Paraguay Belt.Three Major Glaciomarine sediments deposited on shelf domain (Puga Formation) and slope environments (Cuiabá Group). In this Last enviroment the glaciomarine sediments were strongly reworked by turbidites currents. The midle unit inclues Carbonate (Araras Formation) deposited directly on top of glaciomarine sediment, which the changes laterally towards the border of the Craton to muddy limestones (Guia Formation). The upper unit consists of siliciclastic sediments (Raizama and Diamantino formations). Keywords: