Modifications in the trajectory of Capivari river and its possible relations to the meteoritic impact responsible for the formation of the crater of Colônia at the reverse of Serra do Mar-SP.

• Grant number: 08/05527-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2008
• End date: November 30, 2009
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Physical Geography
• Principal Investigator: Déborah de Oliveira
• Grantee: André Henrique Bezerra dos Santos
• Host Institution: Faculdade de Filosofia, Letras e Ciências Humanas (FFLCH). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The Capivari river is located between the crater of Colônia and the scarp of Serra do Mar, near the southern border of the Paulistano plateau, in São Paulo municipality. Its trajectory shows several inflections among those one more conspicuous that marks the transition between its upper and middle course. At this point there is a significant change in the width of the fluvial valley, which becomes narrower downstream, despite there is not significant differences of the basement, predominantly gneisses. We propose that the river had a former S-N trajectory to the interior of the continent, meeting the Jurubatuba river, an affluent of Pinheiros river. A meteoritic impact which formed the crater of Colônia may have destroyed the middle portion of Capivari valley, leading to the diversion of its upstream portion towards Embu-Guaçu drainage basin. A second event, after the impact, may have caused another diversion, eastwards, generating the inflection of Capivari river. This last diversion might be related to the set of fluvial captures in the reverse of Serra do Mar that follows the backwearing of the scarp towards the interior of the continent. This research integrates the project "Reserva Florestal do Morro Grande e Arredores", coordinated by PhD Déborah de Oliveira, and it has the purpose of characterizing the possible former trajectories of Capivari river. We will apply the well-known methods in the study of stream piracy: the identification of possible similarities among gravels, captures elbows, misfit streams, wind gaps and knickpoints.