Trajetórias do Rio Capivari

implicações de um impacto meteorítico na drenagem no reverso da Serra do Mar, São Paulo, Brasil

Abstract

The Capivari river, located between the crater of Colônia and the scarp of Serra do Mar on the south region of São Paulo municipality, has changed its course several times since the area has been hit by a meteoritic impact in the Pliocene. From analysis of hypsometric and geologic maps and observation of drainage patterns in the area, we propose that the formation of the impact crater might have induced a diversion in the trajectory of Capivari river towards Embu-Guaçu drainage basin. This westward diversion is suggested by the topographic continuity of a valley that is shared by both drainage basins in the present, but may have been cut by a continuous stream. The formation of concentric rings under the process of impact cratering and the formation of zones of weakness in rocks due to the impact would explain this diversion. In a later event, the trajectory of Capivari river may have been modified again, southeasterwards to the coast. This second diversion may be contemporary to the set of fluvial captures that follows the regression of the fault-line scarp of Serra do Mar.