Biocronoestratigrafia da Bacia de Pelotas: estado atual e aplicação na geologia do petróleo

Abstract

The biostratigraphic studies of the Brazilian sedimentary basins have providing a support for the exploratory research of energetic and mineral resources, in particular at the continental margin. From new discoveries of hydrocarbon accumulations at the Santos and Campos basins, the south portion of the Brazilian continental margin were converted in an important target of the exploration. Therefore, the biostratigraphic refinement is necessary to detect gaps and to promote an increment on the precision of the lateral correlations in the delimitation and spatial analysis of the potential reservoirs. The actual stage of the bio-chronostratigraphic framework of the Pelotas Basin is presented herein, focusing on its application to the reservoir prospection. The main questions and lacunae on the knowledge are also discussed. In terms of biostratigraphy, the Pelotas Basin remains poorly evaluated, despite publication of important works on the biostratigraphy are known since the 1960’s. A comparison of biostratigraphic schemes proposed for the Tertiary section of the basin allows the inference of diverse hiatuses, identified by the absences of biozones. Hiatuses identified in the 87 Sr/ 86 Sr curve, suggest their relationship with discontinuities in the deposition. Discrepancies between the proposed schemes can be attributed to the particular resolution of the different groups used, the variations in the biostratigraphic criteria and the sampling interval, influencing the biostratigraphic resolution and therefore its potential as a correlation tool.