| Journal: | Revista brasileira de geociencias |
| Database: | PERIÓDICA |
| System number: | 000190533 |
| ISSN: | 0375-7536 |
| Authors: | Klein, Evandro Luiz1 Fuzikawa, Kazuo2 Koppe, Jair Carlos3 Dantas, Maria Sylvia Silva4 |
| Institutions: | 1Companhia de Pesquisa de Recursos Minerais, Belem, Para. Brasil 2Comissao Nacional de Energia Nuclear, Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, Minas Gerais. Brasil 3Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul. Brasil 4Universidade Federal de Minas Gerais, Departamento de Fisica, Belo Horizonte, Minas Gerais. Brasil |
| Year: | 2000 |
| Season: | Jun |
| Volumen: | 30 |
| Number: | 2 |
| Pages: | 322-326 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Artículo |
| Approach: | Analítico |
| English abstract | The Caxias deposit is situated in the Gurupi Auriferous Province of the Paleoproterozoic São Luís Craton, northern Brazil. It is a lode-type gold mineralization associated with a narrow, steeply dipping, NE-trending, shear zone crosscutting a hydrothermalized microtonalite (northern sector) and schists (southern sector). Fluid inclusion studies on vein quartz crosscutting the microtonalite (northern sector) have identified early carbonic and aqueous-carbonic inclusions and late aqueous inclusions, unrelated to the mineralizing event. The CO2 / H2 O ratio and the other microthermometric properties show a wide range of values, which are interpreted as product of heterogeneous trapping of two (partially) immiscible fluids and to deformation-related post-formational processes. The resulting mineralizing fluid has XCO2 : 6-45 mol %; XN2 : < 2.5 mol %; XH2 O: 55-95 mol %; mean salinity of 4.5 wt % NaCl equiv., and moderate density (0.7-1.0 g/cm3 ). Bulk isochores coupled with chlorite geothermometry constrained the P-T entrapment conditions between 262-307ºC and 1.6-3.7 kb. Log ¦O2 for this P-T-X range was estimated between –29.8 and –34.2. Geological characteristics and fluid properties found in the northern sector of Caxias gold mineralization are similar to those described for metamorphic fluids of mesothermal gold deposits |
| Disciplines: | Geociencias |
| Keyword: | Geología, Mineralogía, petrología y geoquímica, Sao Luis, Caxias, Yacimientos, Oro, Brasil |
| Keyword: | Earth sciences, Geology, Mineralogy, petrology and geochemistry, Sao Luis, Caxias, Gold, Deposits, Brazil |
| Full text: | Texto completo (Ver PDF) |
