Cenozoic Sedimentation and Tectonic Deformation in the Central Part of the Potiguar Basin

Abstract

Neogene and Quaternary sedimentary covers occur along the Brazilian coast and have been frequently describedtogether as a single unit. The study of Brazilian sedimentary basins concentrates on their rift phase, whereas the post-riftphase has been considered a tectonic quiescent period. In the Potiguar basin, although post-rift Cretaceous units are wellinvestigated, the Neogene and Quaternary sedimentary covers, as well as their identifi cation and differentiation, are still poorly known. A few previous studies have demonstrated that post-rift sedimentary units with no apparent deformation have a complexdeformation pattern in all scales of observation. The study of this deformation, however, did not include Neogene and Quaternary units.The main aim of the present study is the characterization of Neogene and Quaternary sedimentary units that outcrop in the central partof the Potiguar Basin, State of Rio Grande do Norte, Brazil, and related tectonics. The study has concentrated on the description ofthe Barreiras Formation and overlying Quaternary alluvial, marine, and aeolian deposits at 1:100,000 scale. Facies analyses, grain sizestudies, and luminescence dating were carried out. Ten informal and formal lithostratigraphic sedimentary units were described, inaddition to the Precambrian crystalline basement. The main results indicate that several Quaternary alluvial deposits were previouslymapped as the Miocene Barreiras Formation. It was possible to locate the new boundaries of the Quaternary sedimentary deposits andtheir stratigraphic relationships with older units. In addition, it was possible to identify the major fault systems in the basin that show NW- and NE-trending directions, which coincide with macro landforms. It follows that these major fault systems, mainly the NW trending system, control the deposition of Neogene and Quaternary sedimentary units.

Keywords

• Tectonics
• Potiguar basin
• Cenozoic