Cenozoic sedimentary covers in Jundiaí River catchment – Southeastern Brazil.

Abstract

This paper presents the geological characterization of sedimentary covers in the Jundiaí River Catchment, São Paulo State, Southeastern Brazil, as well as its relationships with the regional geologic evolution. Paleozoic deposits included in Itararé Group, besides Tertiary and Quaternary deposits, cover the Crystalline Basement. The Tertiary deposits constitute local occurrences, because they mostly were removed by erosion, and the remainders are under younger sedimentary covers. They correspond to an ancient alluvial fan system, which source area was the Japi Mountain Range, and their genesis is related to fault scarps that control the higher areas. Discontinuous bodies of colluvial-elluvial deposits are controlled by geologic structures and show, in their composition, massive sand-clayed material with stone lines at the bottom. The alluvial deposits also accompany the main geologic structures. The distribution of these sediments are controlled by local relief, where NW-SE faults caused subsidence of the central portion of the area, giving raise to the configuration of Jundiaí River catchment. The occurrence of alluvial deposits in sites where transtension efforts act is of great importance to the groundwater exploration. The landscape conditioned by endogenic factors shows the importance of neotectonic process in the intraplate environment.