Mapeamento geológico de detalhe da região do Boqueirão, São Sepé - RS

Abstract

The Camaquã Basin holds a broad Volcano-Sedimentary record related to the transition between Pre-Cambrian and Paleozoic. There is a vast array of journals and papers on this matter, and it is common a disagreement among the scientists about the genetic and petrographic characteristics of the basin. The study was conducted in Boquerão Region between Caçapava do Sul e São Sepé – RS. The aim was to delimitate de rock units that outcrops in the area and establish the relation between their contacts. The methodology applied consisted of fieldwork, outcrops detailing, and petrographic studies in a microscopic scale. As a result, it was noticed a huge lithologic variation allowing the identification of five distinctive units. As a result, a map with 1:7000 has created. For a better understanding of the geological setting, a 3D geological model was produced from the map’s data. A comparative study was conducted between the lithological characteristics and stratigraphic position of the mapped units of this study, and the information of previous works by different authors. In the proposed mapping scale, five (5) units were found and named as follows, from the base to the top: Pacote Sedimentar I, - Sucessões de Derrames, - Rochas Piroclásticas, - Veio de Quartzo, - and Pacote Sedimentar II, which correspond to Maricá Group, Hilário Volcanism, Acampamento Velho Formation, Quartz Vein and Santa Fé Formation respectively. The Pacote Sedimentar I is formed by arkoses, litharenites, and conglomerates. The Sucessão de Derrames corresponds mainly to basalts and andesites. The Rochas Piroclásticas are mostly composed of tuffs and welded tuffs. The Quartz Vein is an elongated body with 800m length and 50m width that has a NE-SW orientation. And the Pacote Sedimentar II is formed by conglomerates, sandstones and mudrocks.