2020-01-102020-01-102016-11-04MARTINS, Taynara Cristina Matos. Fácies deposicionais e geologia estrutural do arenito Guamá nas regiões de Irituia e São Miguel do Guamá, Estado do Pará. Orientador: Joelson Lima Soares. 2016. 62 f. Trabalho de Curso (Bacharelado em Geologia) - Faculdade de Geologia, Instituto de Geociências, Universidade Federal do Pará, Belém, 2016. Disponível em: https://bdm.ufpa.br/jspui/handle/prefix/2750. Acesso em:.https://bdm.ufpa.br/jspui/handle/prefix/2750The Guamá Sandstone is a sedimentary unit, limited extent in Bragantina Platform, especially in the regions of São Miguel do Guamá and Irituia in northeast Pará state and still require a better geological detail. It is characterized by thick layers of quartz-sandstone with average particle size, well rounded, well selected and high degree of textural and compositional maturity. Owing to their petrographic features, facies and its ichnological content are similar to those of quartz sandstones of Nhamundá (The Amazon Basin) and Ipu (Parnaíba Basin) formations, it has been suggested a Silurian age for Guamá Sandstone. In general, the layers have massive aspect and few primary sedimentary structures preserved which hinder paleoenvironmental interpretation. Four depositional facies have been described: 1) Massive sandstone with megaripple bedded ; 2) Massive sandstone with bioturbations; 3) Sandstone with wavy and planar lamination and 4) Sandstone with tabular cross bedding with coarse sand in foreset and scattered pebbles. The facies association indicates that the studied deposits were formed on a sandy coastal region covering foreshore and shoreface areas. In structural geology was observed three families of fractures, found in all studied facies and distributed homogeneously, presenting preferred direction N-S, NE-SW and NW-SE; these families fractures have extensional and orthogonal features between each other. In Guamá Sandstone ichnogenera Planolites and Skolithos were identified and commonly comprise a mixture of ichnofacies Cruziana and Skolithos. Planolites and Skolithos are trace fossils usually produced by vermeformes organisms during feeding and housing activities, respectively. Low ichnodiversidade and high abundance of trace fossils suggest stressful conditions during the depositional period. The presence of Skolithos-Cruziana icnofácies mixture may be related to depositional environments of brackish water influenced by defrost water where defrosting fresh water and marine mixture cause salinity variations and affect benthic life. The presence of icnofácies Cruziana-Skolithos in Guamá Sandstone is similar to what is observed in the Nhamundá Formation. Thus, these two units are the record of sandy coastal deposits influenced by glaciations that affected the Amazon region during the Lower Silurian.Acesso AbertoArenito - ParáGeologia estratigráfica – SilurianoFácies (Geologia) - ParáTraços fósseis – ParáCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA::ESTRATIGRAFIATrabalho de Curso - Graduação - Monografia