Prospecto de ouro Matilde: estudo geofísico com integração de dados geológicos, Lavras do Sul - RS

Abstract

This study comprises geophysical and geological data integration in the Matilde Prospectus, located in the state of Rio Grande do Sul, south of the urban area of the city of Lavras do Sul. Inserted in the Sul-rio-grandense Shield, in the domain of São Gabriel Terrain and composed of Granodioritic and Monzogranitic rocks of the Lavras do Sul Intrusive Complex. The objective is to locate and delimit the best areas for gold exploration, defining the possible geometry of the body, through direct and indirect methods, obtaining 2D profiles and 3D model. Through the electroresistivity method, with the electric walking technique and dipole-dipole arrangement, six profiles of 360 m were made, with lateral spacing of 150 m. The direction of the survey was N-S, based on the vertical derivative map of aeromagnetometry, which shows three large lineaments that pass within the study area. The main types of hydrothermal alterations found in thin section and soundings were sericitization, chloritization, change to clay, oxidation and carbonation. There are two main families of structural features, which were defined as discontinuities, both with similar diving directions. One focuses on the initial portions of the profiles and another on the central regions. Thus the six profiles show lateral continuity, related to geoelectric discontinuities, where the delimitation of the zone of interest in the body is in agreement with the magnetic lineation, showing with elongated geometry in the E-W direction. Then, mineral occurrences are in the central portions, associated with hydrothermalized zones, of which they are subordinate to structures.