Interpretação paleoambiental de um afloramento da Formação Serraria da sub-bacia de Alagoas e caracterização petrográfica do nível estratigráfico correlato

• Autor(a) principal: Franco, Luisa Sampaio
• Data de Publicação: 2018
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: http://ri.ufs.br/jspui/handle/riufs/9729
• topic: Geologia; Ensino de geologia; Petroliféros; Sub-bacia de Alagoas; Formação Serraria; Interpretação paleoambiental; Caracterização petrográfica; Estratigrafia; Serraria Formation; Paleoenviroment interpretation; Petrographic characterization; CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA::ESTRATIGRAFIA

The Sergipe-Alagoas Basin is a basin of atlantic continental margin, located in the homonymous states, in northeastern of Brazil, which is characterized by an asymmetric and elongated rift, formed due the fragmentation of the supercontinent Gondwana, at the end of the Jurassic Period. The tectono-sedimentary evolution context of this basin makes it the most complete stratigraphic sequence, including from Paleozoic glacial-marine deposits remnants to marine sequences of Cenozoic Era. This project aim’s is the pre-rift phase of the Alagoas sub-basin, through the study of one outcrop of the Serraria Formation, localizated in Igreja Nova (AL), with the purpose of characterizing its heterogeneities and interpreting its paleoenvironment, as well as petrographically characterizing the stratigraphic level correlated to this outcrop. Therefore, the analysis and characterization of the sedimentary facies, the limiting surfaces, the paleocurrent and the architectural element of this outcrop were performed. As a result, 5 sedimentary facies, 5 hierarchical orders of limiting surfaces and one architectural element were identified and interpreted in this project. The petrographic characterization of this project was realized through the analysis of 5 thin sections of the same stratigraphic level of the outcrop, being them described and grouped in 3 petrofacies. With the obtained data, the outcrop was interpretaded as part of a paleoenviroment within a fluvial channel, characterized by the architectural element of downstrem-accretion deposits (DA), presenting its principal paleoflower to south. Through the qualitative and quantitative analysis of these thin sections, it was possible to characterize the petrofacies texturally as submature to supermature and compositionally as mature, receiving the nomenclature of diagenetic quartz sandstones. The porosity of these rocks was defined as good to excellent, occurring in general in a connected way, besides interpretating these rocks as belonged to Medial Diagenetic Domain of the Serraria Formation, characterized by diagenetic quartz sandstones which suffered intense dissolution of feldspars due the action of telodiagenesis