Paragenesis and evolution of the hydrothermal Bacuri iron oxide-copper-gold deposit, Carajas Province (PA)

Autor(es)

Coelho de Melo, Gustavo Henrique ^[1] ; Soares Monteiro, Lena Virginia ^[2] ; Natividade Moreto, Carolina Penteado ^[1] ; Xavier, Roberto Perez ^[1] ; Delinardo da Silva, Marco Antonio ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas Unicamp, Inst Geociencias, Campinas, SP - Brazil

^[2] Univ Sao Paulo, Inst Geociencias, Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: BRAZILIAN JOURNAL OF GEOLOGY; v. 44, n. 1, p. 73-90, MAR 2014.
• Citações Web of Science: 0

Resumo

The Bacuri copper deposit is located about 9 km east of the world-class Sossego iron oxide-copper-gold deposit in the Carajas Province. It is hosted by the ca. 2.84 Ga Serra Dourada granite, the Bacuri Porphyry, and subordinated gabbro. The Bacuri deposit is situated within the regional-scale, WNW-ESE-trending ductile Canaa shear zone, characterized by early albite, scapolite-magnetite,potassium feldspar and biotite-scapolite-magnetite hydrothermal alteration zones. Copper mineralization was controlled and largely simultaneous to the development of a NE-SW-trending transcurrent fault zone. Within this zone, intense chlorite alteration, silicification and quartz veining overlap previous hydrothermal stages. Copper ore (chalcopyrite-pyrite-magnetite) is disseminated and related to veins and breccias. Chalcopyrite occurs along the mylonitic foliation in chlorite alteration zones, in brecciated quartz-(muscovite-fluorite) and undeformed milky quartz veins and in late potassium feldspar-epidote veinlets with open space textures. The relative temporal history of the Bacuri deposit reveals significant changes in physico-chemical parameters during the system evolution. Contribution of hot hypersaline metalliferous fluids was important during early sodic and potassic alteration stages and related to a regional hydrothermal system developed at relatively deep crustal levels. Influx of externally derived diluted fluids within the NE-SW-trending fault zone favoured the late shallow-emplaced chlorite alteration and silicification, and may have triggered the ore deposition due to decrease of temperature and salinity, accompanied by fO(2) increase and pH decrease. Such significant changes could indicate a hybrid system that evolved in multiple pulses during progressive exhumation. (AU)

• Processo FAPESP: 04/08126-4 - Aplicação de isótopos estáveis na modelagem da gênese dos depósitos de óxido de ferro-Cu-Au da Província Mineral de Carajás, PA: exemplos dos depósitos de sossego e Igarapé Bahia
• Beneficiário: Lena Virginia Soares Monteiro
• Modalidade de apoio: Bolsas no Exterior - Pesquisa
• Processo FAPESP: 03/11163-6 - Aplicação de isótopos estáveis na modelagem da gênese dos depósitos de magnetita-Cu-Au de Igarapé Bahia e de Cu-Au-(W-Bi-Sn) de breves, Província Mineral de Carajás, PA
• Beneficiário: Lena Virginia Soares Monteiro
• Modalidade de apoio: Auxílio à Pesquisa - Programa Primeiros Projetos