Caracterização faciológica da cobertura sedimentar da plataforma continental do Maranhão

Abstract

The Barreirinhas Basin Continental Shelf is located between the 44° W and 42° W meridians and the 0° S and 3° S parallels. It is a complex environment with irregular geometry and morphology, low river flow and a large tidal range (3.75 m). The aim of this study was to classify and characterize marine sediments (granulometry and morphoscopy) and sediment transport trends using the Multi Sediment Trend Analysis (MSTA) model. The surface sedimentary cover of this platform consists mainly of quartz sands. Based on carbonate concentrations, two sedimentary facies were recognized, one terrigenous and one biogenic, the former predominating on the inner continental shelf and the latter on the outer shelf. Muddy sediments from before the Last Postglacial Marine Transgression could be recognized, and are currently undergoing a rapid erosion process. Bathymetry within the sampling grid shows sandy banks at shallow depths and evidence of submarine canyons on the outer shelf in connection with the paltaform break. The MSTA model indicated a trend of transport from both the inner and outer shelf converging on the middle shelf, as a result of an improvement in particle size selection.