Petrogenesis of the migmatites and associated rocks of the costeiro complex, São Sebastião region, north coast of the São Paulo State

Abstract

Migmatites are usually complex rocks that have been objecting to many studies since the initial phase of the development of geological science. Due to great varieties in textures, structures, as well their occurrence in large areas, these rocks attracted the attention of many geologists over the last decades. The main aim of this project is to characterize petrogenetically the migmatites and the medium to high-grade metamorphic rocks of the Costeiro Complex on the northern coast of São Paulo State.Geographically, the study area is located at Juqueriquerê Plateau, limited to the north by the Camburu Fault and to the south by the Atlantic Ocean, and contains essentially migmatitic para-derived rocks intercalated by boudins of antipolitics rocks. Orthogneissic and granitic rocks also occur. The para-derived migmatitic rocks are described as biotite gneisses, sillimanite, and garnet-bearing banded schists and kinzigites. In the different levels and degrees of partial melting, the main structures of these migmatitic rocks vary from stromatic, schlieren-rich to nebulitic. The anfibolitic rocks occur as concordant centimeter- to decameter-wide lenticular bodies and boudins. In order to better understand the petrogenetic process that affected these rocks, outcrop-scale detailed geologic and structural descriptions, microscopic petrography, and lithogeochemical analyzes will be carried out in the rocks near the São Sebastião city. By the end of this project, we expect a pleasant introduction to the student on the scientific methodology, adding a large bag on his geological knowledge, and also to contribute to the understanding of the petrological and tectonic processes that occurred in the Costeiro Complex during the Brasiliano Orogeny. (AU)