CONSIDERAÇÕES SOBRE EVENTOS TERMOCINEMÁTICOS ASSOCIADO AO SOERGUIMENTO DE ÁREAS PRÉ CAMBRIANAS E A SUA RELAÇÃO COM A SUBSIDÊNCIA DA BACIA DO PARANÁ: TRAÇOS DE FISSÃO E PALEOTENSÕES

Abstract

The Precambrian basement of Southeast Brazil along the northeast board of Parana basin is characterized by many bittle reactivations of shear zones that developed during the end of the Brasiliano orogeny. This brittle activity occurred several times during the Phanerozoic, resulting in additional fault movements and uplift of the Pre-cambrian areas. To constrain the uplift (fission tracks) and paleostress phases of the Pre – cambrian areas, in the northeast Parana basin margin, and establishment to relation with the subsidence events of the Parana basin. The results of this study consists of two main domains, which record different episodes of uplift and reactivation of faults: The first domain is denominated Sorocaba, it is located near of the Parana basin and consists of Neoproterozoic rocks and Paleozoic sedimentary units bounded by Campinas fault zone (NE), Jundiuvira fault zone (WNW) and Moreiras fault zone (NE); The second domain consists of Pre-cambrian rocks, Granites rocks and Tertiary sedimentary units, characterized by three principal faults Jundiuvira fault zone (EW), Camanducaia and Extrema fault zone (NE). This with many evidences of reativaction, where was recognized tectonic rocks as pseudotachylytes cataclasites and fault gouges. Based on fission track data, it is associated uplift of basement rocks around the NE margin of the Parana Basin in southeast Brazil was related to the tectonic subsidence and consequent deposition of the Parana basin. The evolution of this basin seems to have been strongly influenced by compressive and extensional events as suggested by Millani (1997) that developed during the subduction of Panthalassan plate under the southwestern Gondwana margin (Ramos,1988) These pulses are recorded as important unconformities in the stratigraphic framework of the Parana basin and the elucidation of the uplift and denudation histories of the basement shield is crucial to the understanding these tectonics effects. Fission track studies (correct ages) indicate the correlation with significant events of cooling in 193Ma (Triassic); 126Ma (Early Cretacic); 89Ma (Late Cretacic) and 69Ma (Late Cretacic). The thermal histories are indicate tectonic uplift117 the Oligocene too.