PETROLOGY OF THE FELDSPATIC MICA SCHISTS FROM XAMBIOA FORMATION ARAGUAIA-GO BELT: COMPOSITIONAL CONTROL IN MICA SCHISTS PARAGENESIS
PETROLOGIA DOS MICAXISTOS FELDSpATICOS DAFORMACAO XAMBIOA (FAIXA ARAGUAIA IGO): CONTROLE COMPOSICIONAL EM PARAGENESES DE MICAXISTOS
| dc.contributor | en-US | |
| dc.contributor | pt-BR | |
| dc.creator | TEIXEIRA, NILSON PINTO | |
| dc.creator | SOUZA, ANTONIO CELSO COSTA DE | |
| dc.creator | DALL'AGNOL, ROBERTO | |
| dc.date | 2017-06-20 | |
| dc.date.accessioned | 2022-12-15T20:27:27Z | |
| dc.date.available | 2022-12-15T20:27:27Z | |
| dc.identifier | https://ppegeo.igc.usp.br/index.php/rbg/article/view/11323 | |
| dc.identifier.uri | https://repositorioslatinoamericanos.uchile.cl/handle/2250/5361134 | |
| dc.description | The Xambioa Formation is the upper inut of the Estrondo Group, which is very well exposed in the northern part of the Araguaia Belt. In the mapped areas(1: 100,000), the Xambioa Formation is composed essentially of mica schists, showing five phases of deformation related to a progressive deformation event. The petrographic studies showed the existence of at least six events of mineral recrystallization. The paragenesis and chemical compositions of the mica schists indicate the original sediments to be composed mainly by pelites and graywackes with minor carbonates. It can be observed, through petrographic study, a relationship between the absence of garnet and the presence of epidote although there is no incompatibility among them. The chemical analyses and the petrological diagrams demonstrate the crystallization of thesemineral to be controled by the CaOcontentof eachsample. When the CaO content increases the epidote crystallization is favored while the reduction of this content favors the crystallization of garnet. This compositional control is evidenced by the erratic distribution of garnet in the map makes it impossible to trace this mineral isograde. Staurolite behaves in a similar pattern. Its crystallization is only possible for certain compositions which are rarely found in the analysed samples. In this case, the main factor is the rock FeO content wich has to be great enough to allow staurolite to crystallize. The paragenesis presentin the micaschists indicate the metamorphism to have reach at least the condition of the upper greenchist facies or more probably, the conditions of the lower amphibolite facies, under high pressure regime (5 to 6 kb). | en-US |
| dc.description | The Xambioa Formation is the upper inut of the Estrondo Group, which is very well exposed in the northern part of the Araguaia Belt. In the mapped areas(1: 100,000), the Xambioa Formation is composed essentially of mica schists, showing five phases of deformation related to a progressive deformation event. The petrographic studies showed the existence of at least six events of mineral recrystallization. The paragenesis and chemical compositions of the mica schists indicate the original sediments to be composed mainly by pelites and graywackes with minor carbonates. It can be observed, through petrographic study, a relationship between the absence of garnet and the presence of epidote although there is no incompatibility among them. The chemical analyses and the petrological diagrams demonstrate the crystallization of thesemineral to be controled by the CaOcontentof eachsample. When the CaO content increases the epidote crystallization is favored while the reduction of this content favors the crystallization of garnet. This compositional control is evidenced by the erratic distribution of garnet in the map makes it impossible to trace this mineral isograde. Staurolite behaves in a similar pattern. Its crystallization is only possible for certain compositions which are rarely found in the analysed samples. In this case, the main factor is the rock FeO content wich has to be great enough to allow staurolite to crystallize. The paragenesis presentin the micaschists indicate the metamorphism to have reach at least the condition of the upper greenchist facies or more probably, the conditions of the lower amphibolite facies, under high pressure regime (5 to 6 kb). | pt-BR |
| dc.format | application/pdf | |
| dc.language | por | |
| dc.publisher | Sociedade Brasileira de Geologia | pt-BR |
| dc.relation | https://ppegeo.igc.usp.br/index.php/rbg/article/view/11323/10789 | |
| dc.rights | Direitos autorais 2017 Revista Brasileira de Geociências | pt-BR |
| dc.source | Revista Brasileira de Geociências; v. 18, n. 2 (1988); 109-121 | en-US |
| dc.source | Revista Brasileira de Geociências; v. 18, n. 2 (1988); 109-121 | es-ES |
| dc.source | Revista Brasileira de Geociências; v. 18, n. 2 (1988); 109-121 | pt-BR |
| dc.source | 0375-7536 | |
| dc.subject | en-US | |
| dc.subject | pt-BR | |
| dc.title | PETROLOGY OF THE FELDSPATIC MICA SCHISTS FROM XAMBIOA FORMATION ARAGUAIA-GO BELT: COMPOSITIONAL CONTROL IN MICA SCHISTS PARAGENESIS | en-US |
| dc.title | PETROLOGIA DOS MICAXISTOS FELDSpATICOS DAFORMACAO XAMBIOA (FAIXA ARAGUAIA IGO): CONTROLE COMPOSICIONAL EM PARAGENESES DE MICAXISTOS | pt-BR |
| dc.type | info:eu-repo/semantics/article | |
| dc.type | info:eu-repo/semantics/publishedVersion | |
| dc.type | pt-BR |