Is there a true delta at the Ribeira de Iguape river mouth, São Paulo State?

Abstract

The study area corresponds to the coastal plain neighboring the Ribeira de Iguape river mouth in the São Paulo State littoral, where the Iguape, Cananeia and Ilha Comprida municipalities are situated. This coastal plain exhibits an area of more than 1,500 km². It has been interpreted as a consequence of shallow marine sedimentation of Pleistocene and Holocene, attributable to Cananeia and Santos transgressions, occurred during the last two interglacial stades named Sangamon and Holocene, intercalated by the last glacial stade named the Wisconsin according to the North-American nomenclature. However, without any scientific fully justifiable evidence, it has been hypothetically postulated that this coastal plain could represent an oceanic delta associated with the Ribeira de Iguape river mouth, which is the most important drainage along the São Paulo State coastline flowing to the Atlantic Ocean. This article has presented the data obtained by essentially sedimentological studies, based on grain size and heavy mineral analyses, which brought important subsidies for a negative response to the question: "is there a true delta at the Ribeira de Iguape river mouth (São Paulo State, Brazil)?".