Lito e paleomagneto estratigrafia das rochas ácidas da província magmática do Paraná, da região de Gramado-RS

• Autor(a) principal: Rossi, Lucas Oliveira [UNESP]
• Data de Publicação: 2018
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/203212; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2018-12-11/000909623.pdf
• topic: Rochas igneas; Geologia estratigráfica; Petrologia; Geoquímica; Paleomagnetismo; Rio Grande do Sul

The Magmatic Province of Paraná is the focus of several studies in the attempt to understand the behavior of the volcanic processes that originated it. Serra Geral Formation is the most important part of this province, with its extensive and thick spills overlapping a large part of the Paraná Basin, ranging from basic rocks to final stages of the spill with acidic vulcanic rocks. These acidic rocks present petrographic and geochemical differences, being divided in Palmas type (ATP), with rhycomits and microporphyriatic riodacites, and Chapecó type (ATC), traquidacites and dacites with porphyritic texture. From this, this work aims to contribute to the development of this Cretaceous magmatic activity, based on an association of litogeochemical, petrographic and paleomagnetic data collected in the region of Gramado-RS, and data from the literature taken from the work The mesozoic flood volcanism of the Paraná Basin petrogenetic and geophysical aspects , written by Piccirilo & Melfi (1988). It was verified that in the region only acidic rocks of the Palmas type occur. Geochemistry was further subdivided into the Jacuí subtype (TiO2>1%), and subtype Caxias (0.9% <TiO2<1%). This separation is corroborated by the petrography of these rocks, because although they present a very similar matrix, vitrified, the Jacuí subtype presents glomeres of phenocrysts of plagioclase, augite and pigeonite. The Caxias subtype, on the other hand, presents plagioclase phenocrysts, only augite as clinopyroxene and usually orthopyroxene (elongated and usually altered crystals). The results of paleomagnetism in the Jacuí subtype samples in all profiles reveal reverse polarization. In the Caxias subtype, the predominant polarization is normal. Stratigraphically it is verified that the Jacuí subtype always occurs below the Caxias subtype, just above the andesites or basalts, as an initial part of the acid magmatism evolution. These results show that even the origin...