Controle tectônico e efeito de contato do Plug Básico Baixa do Meio (Pedro Avelino, RN) em arenitos da formação Açu, Bacia Potiguar
The Northeast of Brazil is a place where three large basic intrusive magmatic events occurred, which affected the sedimentary rocks of the Potiguar Basin and nearby region, during the deposition of its sediments. One of those events, known as Macau Magmatism, that happened during the Cenozoic, resul...
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| Formato: | bachelorThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/34393 |
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| Resumo: | The Northeast of Brazil is a place where three large basic intrusive magmatic events occurred, which affected the sedimentary rocks of the Potiguar Basin and nearby region, during the deposition of its sediments. One of those events, known as Macau Magmatism, that happened during the Cenozoic, resulted in a plug called Baixa do Meio, due to the location’s name of the outcrop. The thermal effects caused by that intrusion caused the formation of buchites, that are rocks resulting from specific pyrometamorphic conditions, low pressure and high temperatures in the sanidinite facies. The plug is composed by basalt in its edges and diabase in the central portion, it does not exceed 30m of exposed area, and it has an oval geometry with extremities NW-SE that are concordant with the fault system of the Afonso Bezerra lineaments. The aim of this work is to characterize the effects caused in the country rock by means of lineaments analysis in aerial photographs, field work, meso and microscopic analysis of collected samples and pre-existing data of other studies in the area. The petrographic analysis made possible the identification of fractures generated by compaction of the grains, the extinction of porosity, partial melting and/or recrystallization of less resistant minerals and the presence of volcanic glass in the matrix, factors that become more evident the closer it gets to the intrusion. The thermic aureole extends up to 55 meters in the sandy terrain on a longitudinal section in the sandstone of the Açu formation. It is assumed that the conditions prevailing at the time varied from 800 to 1100 oC and did not exceed 0.5 kbar in the portions where the event was more intense, due to the area where the pyrometamorphism occurred. |
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