Caracterização petrográfica da intrusão São Félix-01, Monte Carmelo (MG)

Abstract

The western portion of Minas Gerais is known for its diversity of rocks and its geotectonic context, which encompasses rocks belonging to the Paraná Basin, the Tocantins Province, and the São Francisco Craton. During the Late Cretaceous, a large-scale magmatic event occurred in this region. This event was related to the opening of the Atlantic Ocean and left a record of a large number of alkaline rocks, possibly responsible for the diamonds found in the Alto Paranaíba and Triângulo Mineiro regions, which played a crucial role in the development of the area. These alkaline rocks are mainly kimberlites and kamafugites, with local occurrences in the municipality of Monte Carmelo (MG). The Alto Paranaíba Igneous Province (PIAP) consists of a set of alkaline rocks in the region, located on the northern edge of the Paraná Basin. The methodology of this work was based on macroscopic and microscopic descriptions, granulometric separation, scanning electron microscopy (SEM) analyses, and x-ray diffraction (XRD). The São Félix-01 intrusion is located on the edge of a drainage area, highly weathered, with saprolite formation. The intrusion was classified as a kamafugite (mafurite) with a dark gray color, isotropic, ultramafic, holocrystalline, and subphaneritic, with crystals ranging from dense to coarse, moderate magnetism, and euhedral to subhedral macrocrystals, mainly of olivine in a fine-grained matrix, which characterizes the porphyritic texture. Its primary mineralogy is mainly composed of olivine, phlogopite, perovskite, diopside, Ti-magnetite, apatite, kalsilite, serpentine, saponite, calcite, and barite, while its secondary mineralogy includes saponite, vermiculite, and serpentine.