Rhyacian to Orosirian short-lived polyphase deformation and migmatization in northernmost São Francisco Craton, Brazil

Abstract

The Minas-Bahia Orogen, which is Siderian-Orosirian age, is exposed in the northern sector of the São Francisco Craton and in its African counterpart, the Congo Craton. In this sector, two orogenic domains outcrops with geological evolution and terrains with different trends: Western and Eastern Bahia. The advance of scientific knowledge in the northeast of the West Bahia Orogenic Domain has revealed the existence of more tectonic terrains than those traditionally delimited, and reveal the presence of juvenile terranes and cratonic crust separated complex zones where they interacted. The region of interaction between the Gavião and Bom Jesus da Lapa Paleoplate has been the subject of debates about the tectonic significance of granulitic rocks with Meso-Neoarchean protoliths, which are intruded by Rhyacian - Orosirian granitoids. The set of geological data presented in this article demonstrates that the metatexite migmatites with felsic granulitic paleosome and charnockitic neosome were generated during the initial phases of the collision between these two paleoplates, between 2068 and 2058 Ma. The structural mass transport is from NW to SE. The youngest migmatization event, in high amphibolite facies, occurred during NNW-SSE trending sinistral strike-slip tectonics as suggested by the emplacement of Dn+3 neosomes controlled by S/C/C' structures, in between 2049–2000 Ma. The interpreted tectonic model is complex and involves the accretion and collision among Bom Jesus da Lapa, Gavião and Jequié paleoplates during the Rhyacian-Orosirian, contributing to the advancement of knowledge of tectonic pieces and their interactions that contributed to the formation of Columbia supercontinent.