Geochemical modeling of gold precipitation conditions in the Bloco do Butiá Mine, Lavras do Sul/Brazil
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Academia Brasileira de Ciências
2005
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| author | Gilles Berger |
| author_facet | Gilles Berger |
| contents | Geochemical modeling of gold precipitation conditions in the Bloco do Butiá Mine, Lavras do Sul/Brazil Gilles Berger José C. Frantz André S. Mexias Márcia E. B. Gomes Milton L.L. Formoso Norberto Dani Everton M. Bongiolo Multidisciplinaria (Ciencias Naturales y Exactas) gold fluid pyrite sulfur rock interaction A geochemical modeling of gold deposition was performed using the EQ3/EQ6 software package usingconditions inferred from geological, petrographic, geochemical and fluid inclusion data from the Bloco doButiá gold mine, Lavras do Sul, RS. Gold in the mine occurs only in the pyrite structure (invisible gold).The pyrite occurs associated with white mica (phengite) in the zone of phyllic alteration. The process ofgold deposition showed to be related to temperature and pH decrease. The pH decrease was fundamental togold deposition by destabilization of sulfur species [Au(HS)−2 , HAu(HS)02and Au(HS)0] dissolved in theaqueous solution, being Au(HS)0 the main gold transporting complex. The addition of KCl is hard to acceptas cause of gold precipitation because no Cl was detected in phengite. However, the geochemical massbalance calculation resulted in the gain of some potassium in the zone of phyllic alteration. The precipitationof pyrite (± auriferous) may have been strongly influenced by iron availability resulting from dissolutionof ferrous chlorites by the fluids responsible for phengite deposition. The low salinity in quartz grain fluidinclusions from the propylitized wall rock also indicates the little importance of chlorine as gold transportingagent. Sulfur, and not chlorine, compounds must have dominated the gold transporting complexes in theBloco do Butiá gold area. 2005 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32777410 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.4 Vol.77 |
| format | Artículo científico |
| id | redalyc_32777410 |
| institution | Redalyc |
| language | en |
| publishDate | 2005 |
| publisher | Academia Brasileira de Ciências |
| spellingShingle | Geochemical modeling of gold precipitation conditions in the Bloco do Butiá Mine, Lavras do Sul/Brazil Gilles Berger Multidisciplinaria (Ciencias Naturales y Exactas) gold fluid pyrite sulfur rock interaction Geochemical modeling of gold precipitation conditions in the Bloco do Butiá Mine, Lavras do Sul/Brazil Gilles Berger José C. Frantz André S. Mexias Márcia E. B. Gomes Milton L.L. Formoso Norberto Dani Everton M. Bongiolo Multidisciplinaria (Ciencias Naturales y Exactas) gold fluid pyrite sulfur rock interaction A geochemical modeling of gold deposition was performed using the EQ3/EQ6 software package usingconditions inferred from geological, petrographic, geochemical and fluid inclusion data from the Bloco doButiá gold mine, Lavras do Sul, RS. Gold in the mine occurs only in the pyrite structure (invisible gold).The pyrite occurs associated with white mica (phengite) in the zone of phyllic alteration. The process ofgold deposition showed to be related to temperature and pH decrease. The pH decrease was fundamental togold deposition by destabilization of sulfur species [Au(HS)−2 , HAu(HS)02and Au(HS)0] dissolved in theaqueous solution, being Au(HS)0 the main gold transporting complex. The addition of KCl is hard to acceptas cause of gold precipitation because no Cl was detected in phengite. However, the geochemical massbalance calculation resulted in the gain of some potassium in the zone of phyllic alteration. The precipitationof pyrite (± auriferous) may have been strongly influenced by iron availability resulting from dissolutionof ferrous chlorites by the fluids responsible for phengite deposition. The low salinity in quartz grain fluidinclusions from the propylitized wall rock also indicates the little importance of chlorine as gold transportingagent. Sulfur, and not chlorine, compounds must have dominated the gold transporting complexes in theBloco do Butiá gold area. 2005 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32777410 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.4 Vol.77 |
| title | Geochemical modeling of gold precipitation conditions in the Bloco do Butiá Mine, Lavras do Sul/Brazil |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) gold fluid pyrite sulfur rock interaction |
| url | https://www.redalyc.org/articulo.oa?id=32777410 |