O processo de analcimização de um kamafugito (luz262) do centro-oeste mineiro
The present paper is a petrographic study of the primary and secondary phases of a kamafugitic rock, intrusion named as Luz262, found in an outcrop nearby BR262, nearby the town of Luz in the middle west of Minas Gerais. The kamafugite is composed by olivine partially replaced by serpentine, clinopy...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2018 |
| País: | Brasil |
| Institución: | Universidade Federal de Minas Gerais (UFMG) |
| Repositorio: | Repositório Institucional da UFMG |
| Idioma: | portugués |
| OAI Identifier: | oai:repositorio.ufmg.br:1843/76094 |
| Acceso en línea: | https://doi.org/10.18285/geonomos.v26i1.1233 http://hdl.handle.net/1843/76094 |
| Access Level: | acceso abierto |
| Palabra clave: | Rochas ígneas alcalinas Petrologia Rochas Ígneas Alcalinas |
| Sumario: | The present paper is a petrographic study of the primary and secondary phases of a kamafugitic rock, intrusion named as Luz262, found in an outcrop nearby BR262, nearby the town of Luz in the middle west of Minas Gerais. The kamafugite is composed by olivine partially replaced by serpentine, clinopyroxene, perovskite, flogopite, opaques, leucite pseudomorphs (analcime), veins of natrolite and interstitial material (volcanic glass/feldspathoid). The rock contains sedimentary xenoliths of siltite, mainly constituted of orthoclase from the Serra da Saudade Formation, as well as autoliths composed basically of clinopiroxene, perovskite, opaques, apatite, leucite pseudomorphs and natrolite. The rock is classified as leucite-mafurite based on the limited presence of leucite (around 10% modal), besides the probable presence of interstitial kalsilite, as previously described on similar rocks of the Mata da Corda Group from the Alto Paranaíba Province. By using petrographic analysis with optical microscope, mineralogical analysis by x-ray diffraction and chemical microanalysis with electron microprobe it was determined that the feldspathoids originally potassic, suffered a secondary change process of K by Na, with transformation of leucite and kalsilite to analcime. |
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