The Araguaia belt, Brazil : part of a neoproterozoic continental-scale strike-slip.

Abstract

The Araguaia Belt is part of the Tocantins Orogen, a Neoproterozoic orogen that formed during the collision between the Amazonia, São Francisco/Congo and West African Paleo-Continents. This collision contributed to the assembly of West Gondwana. We mapped parts of the Araguaia Belt in its south and central portions in northern Brazil. Our mapping suggests two phases of deformation. The first resulted in the development of N-S trending amphibolite-facies transpresssional structures with a reverse-sinistral movement with vergence towards the Amazonian Craton on the west. The age of this deformation phase is possibly Paleoproterozoic. The second phase generated N-S dextral strike-slip faults that cross-cut older structures. This phase was accompanied by retrograde metamorphism. We propose that these strike-slip faults connect with the east-west trending dextral strike-slip faults in the Borborema Orogen on the northern margin of the São Francisco Craton. Movement on faults fringing the Amazonian Craton combined with that of the Araguaia-Borborema strike-slip system, accommodated lateral escape of terranes wedged between the Amazonian and São Francisco-Congo Cratons during the Neoproterozoic.