Gomes, SD, Berger, S, Figueiredo e Silva, RC et al. (5 more authors) (2018) Oxide chemistry and fluid inclusion constraints on the formation of itabirite-hosted iron ore deposits at the eastern border of the southern Espinhaço Range, Brazil. Ore Geology Reviews, 95. pp. 821-848. ISSN 0169-1368
Abstract
The Piçarrão and Liberdade deposits contain high-grade iron orebodies (>65% Fe) hosted in the Guanhães Group itabirite, that are associated with pegmatite veins and bodies. Fluid inclusion studies in quartz veins associated with the high-grade orebodies show that medium to high salinities (25–28 wt% NaCl eq.) and temperatures (275–375 °C) fluids are associated with the silica leaching that led to the iron enrichment. Mineral chemistry studies by LA-ICP-MS in the iron oxides demonstrate that metasomatic processes were responsible for the mineralogical transformations of magnetite to hematite and for subsequent hematite recrystallization. These processes are related to the iron upgrade in the itabirite and the formation of high-grade orebodies. The oxidation of the magnetite to martite is associated with an enrichment in P and As, and depletion in Mg, Ti and Co; as observed in martite crystals compared to their matching kenomagnetite rims. On the other hand Ti and Mo are enriched in hematite crystals that recrystallized from martite. In this case Ti behaved as an immobile element, and its enrichment is accompanied by the depletion of most of the trace elements. A second stage of magnetite formation precipitated with quartz in discordant veins and is oxidized to martite-II. These quartz-martite-II veins contain low salinity and temperature fluid inclusions that record an episode of meteoric fluid influx. The results of the LA-ICP-MS analyses on the fluid inclusions from pegmatite and quartz veins associated with the high-grade iron bodies indicate the contribution of anatectic fluids in the evolution of the metasomatic events.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 Elsevier B.V. This is an author produced version of a paper published in Ore Geology Reviews. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Fluid inclusions; LA-ICPMS; Iron Ore |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 06 Apr 2018 14:28 |
Last Modified: | 30 Aug 2024 08:47 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.oregeorev.2018.03.025 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:129313 |