Characteristics of sedimentary deposits cement in the Bauru Basin: Presidente Prudente Region, State of São Paulo, Brazil.

Abstract

This paper presents partial results of a research on cementation of sedimentary rocks in the Presidente Prudente Region, State of São Paulo, Brazil, based on surface and sub-surface data, related to a project of groundwater management. According to recent mapping, the studied area is geologically located on Upper Cretaceous sedimentary deposits of the Bauru Basin. The results demonstrate a correlation between the degree of cementation and the types of petrographic facies. They also indicate that a remarkable petrographic distinction, located in the eastern portion of the area, is associated to tectonic events. The presence of analcime in the cement is probably due to hydrothermal processes, which may be associated to the tectonic events. The research demonstrates a pH variation of groundwater according to the deepness of wells, which is related to the hydrochemical behavior of minerals composing the sedimentary rock cement, and shows that the less cemented layers are the most valuable aquifers