Ofiolitos na região do Cerro Mantiqueira: integração geofísica e geológica, Lavras do Sul, RS

Abstract

Studies on lithotypes called ophiolites began in the 19th century, with the main research conducted in Europe and North America focusing on the worldwide known Troodos (Cyprus) and Semail (Oman) ophiolites. In Brazil, surveys were rare until the 20th century and, only from the 21st century, there are records of more expressive geological information. Even so, ophiolitic complexes lack a greater volume of scientific research and, mainly, an integration of studies already carried out. Most are predominantly Neoproterozoic in age and are distributed in Brazilian mobile belts located in the provinces of Tocantins, Borborema, and Mantiqueira. In the state of Rio Grande do Sul there are occurrences of ophiolitic complexes in the Dom Feliciano belt, which belongs to the southern portion of the Mantiqueira Province. In the geological understanding and several associated features, the application of geophysical methods has represented an important contribution throughout history. In the 40s, seismic was important for the mapping of the ocean floor and, later, for the consolidation of the plate tectonics theory, which is decisive for the study of the evolution and accommodation of ophiolitic complexes. With technological advances in the following decades, the use of airborne geophysical equipment allowed regional recognition of areas without geological knowledge. Facilitating and assisting in the identification of the most diverse structural forms, and, also, the contrasts of anomalies that allowed the discovery of lithologies, mineral deposits, and other important features for the recognition of geology worldwide. This study main purpose was integrate geological information (detail and regional mapping, chemical analysis and mineral occurrences), geophysical (aeromagnetometry and aerogamaespectrometry) and geomorphological (variation of the relief and the slope of the terrain) in an ophiolitic complex known as Cerro Mantiqueira located at 15 km and SW of the city of Lavras do Sul, Rio Grande do Sul state, Brazil. Geophysical-geological integration is an important contribution to understanding the dimensions and geometries of lithological bodies, regional discontinuities/structures, and to the subsequent definition and mapping of similar lithological bodies. Additionally, the use of geomorphological information offered important assistance in the quality control (signal) of geophysical data and, also, in the identification with better precision of structural and lithological features.