Integração de métodos potenciais (gravimetria e magnetometria) na caracterização do embasamento da região sudoeste da bacia de pelotas, sul do Brasil

Abstract

Through the integrated application of gravity and magnetic methods, it was intended to contribute to structural and compositional characterization of Pelotas Basin basement. The study area is the south region of Rio Grande do Sul Coastal Province, located between latitudes 31o45' and 34oS and longitudes 52o and 53o30' W. The interpretation of potential methods maps into a Geographic Information System (GIS) allowed verifying a complex structuration and a compositional heterogeneity of the bedrock. These structures are related to the Uruguaio-Sul-Rio-Grandense Shield evolution and with South Atlantic Ocean opening. A negative gravity anomaly in Banhado do Taim area was interpreted as a topographic low in the basin basement. In this region, previous works identified a segmentation in the Pleistocene depositional systems of the Rio Grande do Sul Coastal Plain. The presence of a basement low in the same position of the identified segmentation indicates that the stratigraphic record of the region was controlled by the basin basement. Therefore a control of geologic inheritance in the area is suggested, probable related to fault reactivation and differential subsidence associated with the bedrock compositional heterogeneity. Future studies with data acquisition in not covered areas (lagoons and swamps) and their integration with other methods could be able to improve and to test the present interpretations. © 2009 Sociedade Brasileira de Geof́i{dotless}sica.