Caracterização e evolução de sistemas de ilhas barreiras tropicais no litoral de Macau, estado do Rio Grande do Norte, NE do Brasil

Abstract

The northern coast of the state of Rio Grande do Norte is classified as a mixed-energy tropical coast and presents a very intense coastal dynamic. Within this context is outstanding the presence of barrier island-spits system, end members of sandy bodies parallel to the coastline, which isolate protected areas from the impact of the open sea. The barrier island-spits systems stand out for having different sedimentary deposits on their marine and terrestrial sides. In this perspective, the characterization and analysis of this system, having the knowledge about the processes that act in these environments and their sedimentary/stratigraphic configuration is of utmost importance for both environmental studies and oil and gas reservoir analogues. The main objective of this study was the characterization of the barrier island-spit systems of the northern coastline of the state, near the city of Macau, RN. The research includes data from bathymetry of tidal channels, surface samples and vibracores collected from sub-environments of the barrier island-spit system. The results indicated channels with depths ranging from 1.3 to -6.3 meters, and the main channel having a 'U' shape. Sandy/muddy banks were identified along the channel margins, as well as two areas featuring 2D and 3D underwater dunes, varying in size from small to large. Six sedimentary facies association interpreted in the cores were associated with tidal channel deposits, tidal flat, tidal inlet shoal, beach/barrier island, aeolian sand and washover. The similarity between the features of the surface samples and the facies described in the cores assisted in the interpretation of the sub-environment associated with each facies association.