Neoproterozoic geotectonic evolution of Tocantins structural province central Brazil.

Abstract

Tocantins Structural Province (TSP) is the main tectonic feature in Central Brazil. It separates two main cratonic areas (former continental plates): the Amazonian Craton to the West and the São Francisco Craton to the East[ Recent geochronological data (U-Pb and Sm-Nd) and structural studies show that the actual structural framework of the province was developed during the Neoproterozoic. It is herein proposed that Brasiliano Orogenic Cycle in the TSP was developed in four broad tectonic stages: 1) an ocean opening stage began possibly 0169 Ma^ 1# an island-arc system development stage started 0999Ma and its amal! gamation lasted until ca[ 799 Ma^ 2 a continental collision stage began ca[ 799Ma with the accretion of the island!arcs to the upper Amazonian plate\ the closure of the Goiás Ocean and the development of a foreland basin upon the lower São Francisco plate^ and 4) a post-collisional stage (549-499 Ma) with the development of transcurrent faults (Transbrasiliano lineaments)\ back!thrust reverse faults\ and intrusion of alkalic granitic plutons.