Mapeamento geomorfológico e sedimentológico da plataforma interna de Baía Formosa - litoral oriental do Rio Grande do Norte

Abstract

Seabed mapping is vital for the knowledge of the ocean, as well as for a better understanding of planet Earth, and essential for marine spatial planning. Even considering the importance of the oceans, less than 20% of the world’s ocean floor has been mapped. This value is even lower around Latin America. In this sense, the aim of this work was to map the geomorphology and sediment distribution, of an area still little explored, of the Brazilian continental shelf, adjacent to the municipality of Baía Formosa, in the Eastern Sector of Rio Grande do Norte State. For this, hydroacoustic methods (interferometric bathymetry and sonography) were applied, associated to seabed sediment samples and in situ scientific diving, for the acoustic signal calibration. Data were processed, analyzed and interpreted in laboratories. The results indicated that the average depth of the studied area is 12 meters, ranging from a minimum of 2.9 meters to a maximum of 21.7 meters; the depth increases offshore, at an average inclination 0.24o. Profiles perpendicular to the coastline showed that the slope is smoother after 700 meters from the shoreline. Additionally, the slope in the northern portion is more accentuated than in the southern one. Based on acoustic backscatter patterns, recognized by the contrast of intensity and textures, morphological features were identified and 6 reflection patterns were classified. These reflection patterns, associated with the type of material present in the seabed, allowed the identification of submerged dunes, beachrock lines and rocky outcrops, in addition to the sedimentological characterization of the study area.