Registros de erosão e progradação revelados por radar de penetração do solo (GPR) na barreira regressiva pleistocênica do complexo deltaico do Rio Paraíba do Sul (RJ)

Abstract

The stratigraphy and depositional architecture of regressive barriers reflect the progradation process due to sea level behaviour and sediment supply, with the possibility of extensive coastal plain formation, as occurs in the Paraíba do Sul River Deltaic Complex (CDRPS). The use of GPR has enabled further discussion about these features by identifying records of erosion phases, high-energy events and reworking by drainage and wind action. The main of this study is to identify the radarfacies of the Pleistocene regressive barrier in the CDRPS, using GPR, and considering the given geomorphological characteristics of the respective coastal plain. A 200 MHz antenna was used, in Common-offset mode; and an 80 MHz, in CMP mode for the depth correction. Sequences of regressive radarfacies were identified (f1, f2, f3 and f4) and other radarfacies associated with the swale infilling (f5), washover fans (7), offshore bars (f3a), and erosional surfaces. These last reflectors represent interruptions in the progradation of the coastal plain, followed by a phase or an erosional event that is express by the truncation of the beach ridge alignment. Thus, it was identifiedthe radarfaciesthat surpass the depositional architecture as the result of progradation, as erosional records and geomorphological dynamics aspects about beach ridges.