Barra de Tabatinga Unit - sedimentological and stratigraphic aspects of a pleitocene marine transgressive pulse-coast of Rio Grande do Norte-Brazil.
transgressive pulse; Pleistocene; sedimentological analysis; isotopic analysis; Barra de Tabatinga Unit
Relative variation of the shoreline and its morphological features are directly associated to tectonic and paleoclimatic interferences. These variations model the locally acting depositional systems, stacking lithostatigraphic units with single signatures, concerning lithotype, sedimentary structures, diagenesis, depositional age and crystallization age of the source rock. A bibliographical survey was carried out in order to consolidate a transgressive pulse dated, through termoluminescence, in 210,000 ± 10,000 years, correlated to the antepenultimate marine transgression peak of the Brazilian coast. Sedimentological and granulometric evaluations point to low energy deposition environments, correlated to intertidal systems, for which were described outcrops, made thin section and granulometer analysis. Sm-Nd isotopic analyses, including sediments bordering the shoreline, were performed aiming the characterization of isotopic signatures and identification of their probable source areas. Association of relative sea level variations, sedimentological characterization and sediment source play a major role in siliciclastic sedimentary successions analysis, thus allowing the reconstruction of tectonic, stratigraphic and geographic parameters. After data processing, it was possible to typify and insert in the regional stratigraphy, Barra de Tabatinga Unit, deposited during a transgressive Pleistocene pulse, thus, of different genesis from the above and below units, respectively Barreiras and Potengi formations.