The Proterozoic Vazante hypogene zinc silicate district, Minas Gerais, Brazil: a review of the ore system applied to mineral exploration
Olivo, Gema R., Monteiro, Lena V.S., Baia, Fernando, Slezak, Paul, Carvalho, Igor, Fernandes, Neil A., Oliveira, Gustavo D., Neto, Basilio Botura, McGladrey, Alexandra, Silva, Adalene M., Moura, Márcia A., and Layton-Matthews, Daniel (2018) The Proterozoic Vazante hypogene zinc silicate district, Minas Gerais, Brazil: a review of the ore system applied to mineral exploration. Minerals, 8 (1). 22.
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Abstract
The Proterozoic Vazante zinc silicate district in Minas Gerais, Brazil, hosts world-class hypogene willemite deposits in dolomitic rocks interbedded with siliciclastic rocks deposited in subtidal to supratidal environments. Willemite ore bodies are structurally controlled along regional NE-trending structures which are interpreted as being active during the Neoproterozoic Brasiliano orogeny. The hydrothermal alteration is characterized by an early stage of Fe-dolomite, which replaced the host dolomitic rocks, followed by precipitation of minor sphalerite and then hematite and willemite. Elements commonly enriched in the zinc ore include As, Ba, Be, Bi, Cd, Co, Fe, Ge, In, Mo, Ni, Sb, Se, U, V and W. Mineralogical, fluid inclusion and isotopic data indicates that mixing of S-poor metalliferous saline fluids with meteoric water favored the formation of willemite ore. Carbonaceous phyllites from the underlying thick siliciclastic sequence show evidence of early enrichment in zinc (and ore-related metals) and remobilization, respectively, prior to and during the Brasiliano orogenic event. This unit is interpreted as a possible source of ore-related elements. It is proposed that during the Brasiliano orogeny, hot (T > 170 degrees C) saline fluids (>15 wt % eq. NaCl) leached metals from siliciclastic source rocks and precipitated willemite ore in the overlying dolomitic sequence along structures that favored mixing with oxidizing meteoric water.
| Item ID: | 54741 |
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| Item Type: | Article (Research - C1) |
| ISSN: | 2075-163X |
| Keywords: | hypogene zinc silicate, willemite, Proterozoic dolomitic basin, Vazante district, mineral exploration, ore system model |
| Copyright Information: | © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
| Funders: | NSERC, CNPq, CAPES, Queen's University, Universidade de Brasília, UNICAMP, Universidade de São Paulo |
| Date Deposited: | 25 Jul 2018 07:42 |
| FoR Codes: | 37 EARTH SCIENCES > 3705 Geology > 370505 Mineralogy and crystallography @ 50% 37 EARTH SCIENCES > 3703 Geochemistry > 370399 Geochemistry not elsewhere classified @ 50% |
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