Temporal evolution of the giant Salobo IOCG deposit, Carajas Province (Brazil): constraints from paragenesis of hydrothermal alteration and U-Pb geochronology

Autor(es)

deMelo, Gustavo H. C. ; Monteiro, Lena V. S. ; Xavier, Roberto P. ; Moreto, Carolina P. N. ; Santiago, Erika S. B. ; Andrew Dufrane, S. ; Aires, Benevides ; Santos, Antonio F. F.

• Tipo de documento: Artigo Científico
• Fonte: MINERALIUM DEPOSITA; v. 52, n. 5, p. 709-732, JUN 2017.
• Citações Web of Science: 16

Resumo

The giant Salobo copper-gold deposit is located in the Carajas Province, Amazon Craton. Detailed drill core description, petrographical studies, and U-Pb SHRIMP IIe and LA-ICP-MS geochronology unravel its evolution regarding the host rocks, hydrothermal alteration and mineralization. Within the Cinzento Shear Zone, the deposit is hosted by orthogneisses of the Mesoarchean Xingu Complex (2950 +/- 25 and 2857 +/- 6.7 Ma) and of the Neoarchean Igarap, Gelado suite (2763 +/- 4.4 Ma), which are crosscut by the Old Salobo granite. Remnants of the Igarap, Salobo metavolcanic-sedimentary sequence are represented by a quartz mylonite with detrital zircon populations (ca. 3.1-3.0, 2.95, 2.86, and 2.74 Ga). High-temperature calcic-sodic hydrothermal alteration (hastingsite-actinolite) was followed by silicification, iron-enrichment (almandine-grunerite-magnetite), tourmaline formation, potassic alteration with biotite, copper-gold ore formation, and later Fe-rich hydrated silicate alteration. Myrmekitic bornite-chalcocite and magnetite comprise the bulk of copper-gold ore. All these alteration assemblages have been overprinted by post-ore hematite-bearing potassic and propylitic alteration, which is also recognized in the Old Salobo granite. In the central zone of the deposit the mylonitized Igarap, Gelado suite rocks yield an age of 2701 +/- 30 Ma. Zircon ages of 2547 +/- 5.3 and 2535 +/- 8.4 Ma were obtained for the Old Salobo granite and for the high-grade copper ore, respectively. A U-Pb LA-ICP-MS monazite age (2452 +/- 14 Ma) from the copper-gold ore indicates hydrothermal activity and overprinting in the Siderian. Therefore, a protracted tectono-thermal event due to the reactivation of the Cinzento Shear Zone is proposed for the evolution of the Salobo deposit. (AU)

• Processo FAPESP: 13/25659-5 - GEOQUÍMICA ISOTÓPICA (Sr, Nd e Pb) APLICADA AO ESTUDO DE SISTEMAS HIDROTERMAIS DE ÓXIDO DE FERRO-COBRE-OURO NEOARQUEANOS E PALEOPROTEROZÓICOS DA PROVÍNCIA CARAJÁS: CARACTERIZAÇÃO DAS FONTES DE METAIS E FLUIDOS
• Beneficiário: Carolina Penteado Natividade Moreto
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 09/18371-0 - Geocronologia e geoquímica isotópica aplicadas à evolução metalogenética do Cinturão Sul do Cobre da Província Mineral de Carajás
• Beneficiário: Carolina Penteado Natividade Moreto
• Modalidade de apoio: Bolsas no Brasil - Doutorado