Petrogênese do Stock Fazenda Lagoas, centro norte do Domínio Macururé, Sistema Orogênico Sergipano

• Autor(a) principal: Fernandes, Diego Melo
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: http://ri.ufs.br/jspui/handle/riufs/11941
• topic: Geociências; Petrologia; Rochas ígneas; Geoquímica; Geocronologia; Magmatismo; Cinturões orogênicos; Monzonito; Domínio Macururé; Monzonite; Petrology; Macururé Domain; CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS

The Fazenda Lagoas Stock (SFL), with 20 km2, with age of cristalization of 623±3,6 Ma and intrusive in the metasediments of the Macururé Domain. The northern boundary of the SFL is affected by the Belo Monte-Jeremoabo Shear Zone (BMJSZ). The rocks presents porphyritic texture, with feldspar as phenocrystals. Two types of enclaves were identified based on the contacts. In the stock dominates quartz monzonites, having monzogranite and subordinate granodiorites. The enclaves are a diorite. The mineralogy consists of alkaline feldspar, plagioclase, biotite, amphibole, quartz. The plagioclase is euhedral, subhedral and presents compositional zoning. Brown mica occurs in aggregates. Kink is present in the biotite and is associated with the rotation of quartz and feldspars to the indication of non-solid state. The biotite is re-equilibred primary and its composition indicates magma with calcium-alkaline affinity. The alkaline feldspar is marked at the B/K ratio. Pargasite and edenite are magmatic and barometric based on total aluminum indicated pressures between 6.7-7.8 kbar (15-20 km) for the monzonites and 7.2-9.8 kbar (20-30 km) for the mafic enclaves. The SFL forming magma is classified as shoshonitic and alkaline calcium of high potassium. Geochemical data of major elements with which SFL were formed in a collision environment with varying degrees of CeN/YbN differentiation ranging from 7 to 104. Evidence in enclaves and as physical zonations in plagioclase and alkali feldspar and total rock chemistry data the evolution of SFL can not be explained by the evolutionary system by fractional crystallization, necessitating an interaction between intermediate magma and mafic magma in a collision environment.