Análise de dados e possíveis implicações petrográficas sobre as rochas do complexo alcalino-carbonatítico de Serra Negra, Minas Gerais

Abstract

The Alkaline-Carbonatitic Complex of Serra Negra is located in the municipality of Patrocínio - MG and is composed of carbonatites that, in general, are mostly associated with dunites and silicate rocks. As for the geotectonic context, it is inserted in the metasedimentary rocks of the Brasília Belt. These caused the deformation of their enclosing during their accommodation, forming the circular dome structure. In the present work, they are predominantly characterized by rocks that present genetic connection, related to each other by processes such as fractional crystallization and immiscibility of liquids. Such processes of magmatic differentiation are frequently evidenced in the generation of several alkaline-carbonatite complexes in Brazil and in the world, and contribute decisively in the generation of these rocks and associated mineralizations. Therefore, from this work, based on petrographic analyzes of core samples of rocks from the Alkaline-Carbonatitic Complex of Serra Negra, the following lithologies were detailed: Apatite-Olivine Phlogopitite with Calcite; Serpentinized Dunite; Phlogopitite with large Calcite veins; Phlogopithite with fine Dolomite veins; Olivine-Serpentine Phlogopitite with Dolomite; Phlogopite and Dunite with Phlogopite; in which there was a predominance of phlogopite, magnetite, carbonate (calcite or dolomite), olivine and serpentine, in addition to variations with apatite and perovskite. This way, this macroscopic and microscopic petrographic characterization, allowed to carry out a comparative analysis, with the data already existing in the literature, to contribute with the understanding of the mineralogical and faciological aspects allied to the processes of magmatic evolution, allowed to suggest as to the evolutionary aspects of the magmatism of the rocks of the Alkaline-Carbonatitic Complex of Serra Negra.