Evolução sedimentar e reconstrução paleoambiental da porção sul do Complexo Deltaico do Rio Paraíba do Sul (CDRPS), litoral norte do Estado do Rio de Janeiro

Abstract

The Paraíba do Sul Deltaic Complex (PSDC), located along the northern coast of Rio de Janeiro State, southeastern Brazil, within the emerged portion of the Campos Basin, records the Quaternary coastal evolution and constitutes an important sediment storage area, making it a region of significant scientific interest. Although it has been investigated since the 1940s, only recent studies based on deep borehole data have revealed its lithological and paleoenvironmental complexity, particularly within the youngest deposits controlled by relative sea-level fluctuations and the evolutionary phases of the Paraíba do Sul River. In the southern sector of the PSDC, where an extensive Pleistocene beach-ridge plain occurs, the lack of robust integration among the available datasets still limits the understanding of the depositional architecture, spatial distribution, and genesis of these deposits. In this context, the present study aims to compile, reinterpret, and integrate subsurface data from boreholes and Ground Penetrating Radar (GPR) sections available in the literature in order to reconstruct the paleoenvironments and develop a stratigraphic model based on sequence stratigraphy. The reinterpretation of borehole data enabled the identification of seven sedimentary facies (A, Ab, Ah, Aa, Aab, Ar, and Arb), grouped into four facies successions: SF-M (marine), SF-FE (fluvioestuarine), SF-CA (beach-ridge plain), and SF-F (fluvial), whose spatial relationships were analyzed through strike and dip correlation sections. The correlation sections reveal pronounced spatial heterogeneity in the distribution of the deposits, highlighting lateral facies changes associated with variations in depositional energy and sedimentary processes. The spatial distribution and vertical relationships among the facies successions indicate that the Quaternary evolution of the study area was controlled by relative sea-level fluctuations, alternating between transgressive phases, forced regression (fluvial incision), and coastal progradation accompanied by the development of beach ridges arranged in clinoforms. The integration of GPR data corroborated the progradational geometry of the beach ridges, whereas the spatial analysis suggested that the irregular beach ridges along the margins of Lagoa Feia are associated with a barrier responsible for the closure of an older inland lagoonal system, in contrast to the younger and more regular beach ridges located near the present-day coastline. The proposed model reveals a heterogeneous depositional architecture resulting from the interaction of marine, fluvio-estuarine, and fluvial processes through time, contributing to a better understanding of the Quaternary evolution of the emerged portion of the Campos Basin.