Sedimentação da plataforma continental do Espírito Santo : do aporte terrígeno à ocorrência de fundos recifais
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Data
2017-02-24
Autores
Vieira, Fernanda Vedoato
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Universidade Federal do Espírito Santo
Resumo
Short and long term processes, such as biological activity, sediment transport, hydrodynamic conditions, relative sea level variation, sedimentary input and pre-existing geology, determine the continental shelf morphology. The study area of this research is the continental shelf of the Brazilian east coast. Its platform presents a variation in its width, being of 240 km in the region of Abrolhos to 50 km in its remainder, accompanied by two distinct sedimentary regimes along the platform, the accommodation and supply regime. Associated with those factors, the coastal region is characterized by the presence of Barrier Formation Traps, Crystalline Basement and Quaternary Coastal Plains. These units are distributed in different forms along the coast. The acquired data had the objective to investigate how the long term processes influence the occurrence and distribution of the heterogeneous funds along the platform. The results showed four different reef structures, isolated type 1 and 2 reefs, concretions / crusts, paleovalleys bioconstructions, and an extensive rhodoliths funds throughout the study area. Mud deposits were restricted to the mouth of the Doce river, extending toward the north of the platform. The remainder of the platform is composed of carbonate sediments and terrigenous sand to the north. In the region southern of the Doce river the platform presented a carbonate domain with significant changes in its morphology, with the presence of paleovalleys, irregular structures associated with hardbottoms. For the region to the north, the platform presents a more homogenous morphology, with the presence of the delta of the Doce river and a widening of the platform in the region of Abrolhos. Thus, the geomorphology evolution of the platform was related to the long term processes, and these processes differentiated the faciology of the platform.
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Antecedent geology , Geologia antecedente , Irregular structures , Estruturas irregulares , Rhodolith funds , Fundos de rodolitos