Aplicação de radar de penetração no solo em depósitos cenozóicos da praia do Atalaia, município de Salinópolis (PA)

Abstract

The Cenozoic deposits have their study limited in the Bragantine region, due to the scarcity of good outcrops. In view of this factor, a new methodology of shallow investigation involving Ground Penetrating Radar (GPR) has been applied in these deposits, in order to provide additional information that allows the reconstruction of their depositional environments and evolutionary history. This equipment is based on the emission of electromagnetic waves through antennas that record different lithologies, based on their physical and chemical properties. This method was applied at Atalaia beach, municipality of Salinópolis (northeastern Pará state), where 29 profiles were collected that allowed us to distinguish the following reflection patterns: 1) stratigraphic surfaces; 2) continuous parallel and discontinuous sub-parallel reflection; 3) hyperbolic reflection; 4) chaotic reflection; 5) sigmoidal-type reflection; 6) mound reflection; 7) tilted reflection; and 8) channel reflection. The results of the acquired sections were satisfactory, due to most of them having high resolution quality. Based on the mapping of high frequency reflections (stratigraphic surfaces), three stratigraphic units can be recognized in the study area: units AI and A2 (Fm. Pirabas), characterized by high frequency reflections of mound, hyperbolic and discontinuous sub-parallel patterns, respectively; unit B (Fm. Barreiras), where there is a predominance of chaotic reflections; and units Cl, C2, and C3 (Post-Barrier Sediments), represented predominantly by parallel continuous, sigmoidal, and channel reflections, respectively. The applicability of GPR in these deposits proved to be very effective in the faciologic and stratigraphic characterization of the studied area.