O graben de cananeia

Revista Brasileira de Geociências

26(3): 139-150, junho de 1996

O GRÁBEN DE CANANÉIA
LUIZ ANTONIO PEREIRA DE SOUZA*; MOYSÉS GONSALEZ TESSLER** & VICENTE LUIZ GALLI*
Abstract THE Cananéia graben This paper aims to contribuite for the best understanding of the geological evolution of Cananéia-Iguape coastal plain by using Gravity method. Gravity survey was performed on Cananéia-Iguape region in the southern part of the State of São Paulo, Brazil. The survey was conducted on 280 gravity stations along this area, which has never been surveyed before by using this method. Analysis of achieved data allowed the identification of two significant gravity anomalies: one refers to a prominent gravity high related to the basement rock reached at a deph of 47 meter (well IGG-1) ;the other one, refers to a large gravity low and corresponds to a thick sediment basin located in the central portion of Cananéia Island and southern part of Comprida Island. Two topographic profiles of the basement rock in the surveyed area were achieved by analysing the gravity data along two longitudinal modelled cross-sections of Comprida Island. It shows a thickening of the sedimentary deposit towards the continent in the area of gravity low. The interpretation of gravity data in conjunction with geological and aeromagnetic data shows that the evolution of this coastal plain may be conditioned by a system of normal faults, which may define the graben here named Cananeia Graben. Keywords: Cananeia, Cananeia Graben, Iguape, coastal geology, gravity Resumo Este trabalho visa contribuir para o estudo da evolução geológica da planície costeira Cananéia-Iguape, litoral sul do Estado de São Paulo, tendo como base dados geofísicos obtidos através do método de Gravimetria. Foram estabelecidas 280 estações de gravimetria abrangendo um setor da costa do Estado de São Paulo, até então não coberto por levantamentos desta natureza. A análise dos dados propiciou a identificação de um alto gravimétrico