Tectonics of Brasília orogen at Southern margin of São Francisco Craton: a paleogeographic, metamorphic and structural perspective

Abstract

The Brasília Orogen, in the southern marginal portion of the São Francisco Craton, records the collision between the Sanfranciscana and Paranapanema neoproterozoic tectonic plates. This orogen, organized in the Socorro-Guaxupé Nappe and Andrelândia, Carrancas and Lima Duarte nappe systems, is the object of study of the present research proposal. The recognition of paleotectonics features of the colliding Sanfranciscana and Paranapanema plates, their major paleogeographic characteristics developed during the convergence, pre- and sin-collision evolution, thermal regime and associated structures generated during subduction, collision, thermal relaxation, and orogenic collapse, is the main subject of the present proposal. The targets that make up the main subject may be accomplished with: the study of provenance of the sedimentary sequences; metamorphic petrology, which will allow building up a geodynamic frame for the orogenic domain and; structural geology, in the search for the records of the deformation regimes that characterized the extrusion dynamics during the exhumation of the nappe systems, the pattern of isograds and their relationship with the orogenic thermal structure during the orogeny. The systematic field work will have priority as the foundation for structural geology and metamorphic petrology, bulk rock and mineral chemistry, geochronology, isotopic geology in rocks and minerals by in situ analyses or else, which will be used in the construction of a neoproterozoic tectonic frame for the southern Brasília Orogen. (AU)