Tectonometamorphic evolution of the Embu Terrane and relationships with adjacent terranes in the Southern Ribeira Belt (São Paulo, Brazil)

Abstract

The Embu Terrane is inserted in the central and southern portions of the Ribeira Belt, in the latter case together with the Apiaí, Curitiba and Paranaguá Terranes. It is composed of a lower to upper amphibolite facies metasedimentary rock assemblage with concordant intercalations of calc-silicate, metaultramafic and metamafic rocks and quartzite. This terrane is one of the key elements in understanding the geotectonic evolution of the Ribeira Belt, about which there are currently two opposing geotectonic models. One of the models considers the Ribeira Belt as a collisional orogen, while the another interprets it as an intracontinental orogen. This project aims to quantify the metamorphic process recorded in the Embu Terrane, especially in its western portion, to complement existing data and to compare these two models of tectonic evolution. In addition the project proposes to study the southeastern boundary between the Embu Terrane and adjacent terranes (Apiaí, Costeiro and Curitiba Terranes), along the Cubatão Megafault, which represents the largest structure of the Ribeira Belt. The tectonic role of the Cubatão Fault is also contentious, being interpreted as a suture zone or a late lateral scape zone. The aims of the project are to be achieved using the following methods: regional and detailed field work, petrography, geothermobarometry, microstructural analysis, crystallographic fabrics and isotopic geochronology.