ARQUITETURA E EVOLUÇÃO DEPOSICIONAL DA SUCESSÃO SEDIMENTAR PLEISTOCENO TARDIO-HOLOCENO (ÚLTIMOS ~20 Ka) DA BAÍA DE SEPETIBA (RJ)
Architecture and Depositional Evolution of the Latest Pleistocene-Holocene (last ~20ky) Sedimentary Succession of Sepetiba Bay (RJ)
DOI:
https://doi.org/10.5016/geociencias.v39i03.14366Abstract
The Sepetiba Bay, western coastal area of Rio de Janeiro state, consists of an embayment where estuarine conditions prevail, due to its limited contact to open ocean being isolated by a barrier island of ~40 km extent - restinga da Marambaia. The present study aims at investigating the stratigrahic evolution of the bay’s infilling units, based on seismic anlysis of ~800 km of high-resolution reflection seismic profiles. Seismic analysis was coupled with previously dated horizon on the Rio de Janeiro continental shelf (14C AMS), as well as with recently-dated sedimentary evolutional stages of the Marambaia barrier island (14C AMS/OSL). Integration of all results revealed the existence of a transgressive-highstand sedimentary sucession (up to 30 m thick) composed of units U2-U5 which testifies the onset and evolution of estuarine conditions in the Sepetiba area: an open ocean estuarine system (deposition of unit U2) progressively envolved into more isolated estuarine conditions (depositions units U3-U4), until attaining the configuration of a low energy estuarine environment no longer in direct connection with the open sea (deposition of Unit U5) related to the constructional phases of the Marambaia barrier island itself.
Palavras-chave: Transgressive deposition; Paleoestuarine system; Latest Pleistocene-Holocene transgression.