Recognition of Mesozoic-Cenozoic tectonic on the eastern border of Paraná Basin using apatite fission track in the Pitanga Dome (southwest of Rio Claro, SP).

Abstract

Mesozoic-Cenozoic tectonics on the eastern border of Paraná Basin was deduced by geochronologic study of one important structural feature known as Pitanga Dome, located at southwest of Rio Claro (State of São Paulo), which, like other structures of same type, is coincident to some important structural lineaments, originated by reactivation of pre- existent structures in the basement. The geochronologic method used was the apatite fission track dating, which allow thermal modeling from 120oC to room temperature. Using apatite grains from sedimentary rocks the thermal history could be modeled for the studied area, as the data of each sample due to the heating at the Early Cretaceous by the Serra Geral magmatism present homogeneity. Besides the post-magmatism cooling marked by ages (Early Cretaceous), the main cooling times were detected: during Late Cretaceous, Paleocene, and, with minor importance, during Miocene. These periods are related to important tectonic events occurred in Southeastern Brazil, recognized in the crystalline basement. It is clear the influence of the upward tectonic of the adjacent basement on the basin interior, and the formation of structures like the Pitanga Dome