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In-situ U-Pb geochronology and sulfur isotopes constrain the metallogenesis of the giant Neves Corvo deposit, Iberian Pyrite Belt

In-situ U-Pb geochronology and sulfur isotopes constrain the metallogenesis of the giant Neves Corvo deposit, Iberian Pyrite Belt
In-situ U-Pb geochronology and sulfur isotopes constrain the metallogenesis of the giant Neves Corvo deposit, Iberian Pyrite Belt
© 2018 Elsevier B.V. The large-scale, high-grade Sn ores and the Cu-Sn metal association in the volcanic massive sulfide (VMS) ores in Neves Corvo are unique among VMS deposits, not only in the Iberian Pyrite Belt but also worldwide. Thus, the exceptional nature of the Neves Corvo deposit calls for unusual metallogenic processes. Previous efforts to constrain these processes have been hampered by a lack of high precision ages for the mineralization. This has led to a debate as to whether tin mineralization occurred at the same time as the associated volcanism and VMS-style mineralization, or is the result of later processes events associated with the Hercynian orogeny. We report in-situ U-Pb dating results of hydrothermal cassiterite and sulfur isotopic compositions of sulfides in the Neves Corvo deposit that place tight constraints on the timing of mineralization and on the origin of the hydrothermal ore-forming fluids. The cassiterite samples yield U-Pb ages of the Sn mineralization of 363–366 Ma; identical to the age of the host volcanic rocks. δ34S values range from −32.3‰ to +17.4‰ among the different VMS ore types and are largely consistent with microbiological reduction of seawater sulfate, but with some positive values resulting from thermochemical sulfate reduction. In contrast, the Sn-rich ores have a limited range in δ34S that clusters near 0‰ which suggests derivation from magmatic fluids. Hence, the unusually high Sn grades at the Neves Corvo deposit are interpreted to be derived from fluids exsolved from a hidden granitic source essentially synchronous with formation of the volcanic rocks and VMS mineralization.
Cassiterite U-Pb geochronology, Iberian Pyrite Belt, In-situ sulfur isotopes, Neves Corvo Cu-Sn VMS deposit
0169-1368
223-235
Li, Xiang
b7a31e1a-3276-4377-82a8-aaed24b0e08e
Zhao, Kui-Dong
bd5bd864-d7d0-40b4-ae43-37cdc7632a37
Jiang, Shao-Yong
dc929006-69ac-4366-bf2b-dc97527602d3
Palmer, Martin
d2e60e81-5d6e-4ddb-a243-602537286080
Li, Xiang
b7a31e1a-3276-4377-82a8-aaed24b0e08e
Zhao, Kui-Dong
bd5bd864-d7d0-40b4-ae43-37cdc7632a37
Jiang, Shao-Yong
dc929006-69ac-4366-bf2b-dc97527602d3
Palmer, Martin
d2e60e81-5d6e-4ddb-a243-602537286080

Li, Xiang, Zhao, Kui-Dong, Jiang, Shao-Yong and Palmer, Martin (2019) In-situ U-Pb geochronology and sulfur isotopes constrain the metallogenesis of the giant Neves Corvo deposit, Iberian Pyrite Belt. Ore Geology Reviews, 105, 223-235. (doi:10.1016/j.oregeorev.2018.12.023).

Record type: Article

Abstract

© 2018 Elsevier B.V. The large-scale, high-grade Sn ores and the Cu-Sn metal association in the volcanic massive sulfide (VMS) ores in Neves Corvo are unique among VMS deposits, not only in the Iberian Pyrite Belt but also worldwide. Thus, the exceptional nature of the Neves Corvo deposit calls for unusual metallogenic processes. Previous efforts to constrain these processes have been hampered by a lack of high precision ages for the mineralization. This has led to a debate as to whether tin mineralization occurred at the same time as the associated volcanism and VMS-style mineralization, or is the result of later processes events associated with the Hercynian orogeny. We report in-situ U-Pb dating results of hydrothermal cassiterite and sulfur isotopic compositions of sulfides in the Neves Corvo deposit that place tight constraints on the timing of mineralization and on the origin of the hydrothermal ore-forming fluids. The cassiterite samples yield U-Pb ages of the Sn mineralization of 363–366 Ma; identical to the age of the host volcanic rocks. δ34S values range from −32.3‰ to +17.4‰ among the different VMS ore types and are largely consistent with microbiological reduction of seawater sulfate, but with some positive values resulting from thermochemical sulfate reduction. In contrast, the Sn-rich ores have a limited range in δ34S that clusters near 0‰ which suggests derivation from magmatic fluids. Hence, the unusually high Sn grades at the Neves Corvo deposit are interpreted to be derived from fluids exsolved from a hidden granitic source essentially synchronous with formation of the volcanic rocks and VMS mineralization.

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More information

Accepted/In Press date: 28 December 2018
e-pub ahead of print date: 28 December 2018
Published date: 1 February 2019
Keywords: Cassiterite U-Pb geochronology, Iberian Pyrite Belt, In-situ sulfur isotopes, Neves Corvo Cu-Sn VMS deposit

Identifiers

Local EPrints ID: 429586
URI: http://eprints.soton.ac.uk/id/eprint/429586
ISSN: 0169-1368
PURE UUID: 410b16c2-690e-4f0b-8cae-bd9614a5acc7

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Date deposited: 29 Mar 2019 17:30
Last modified: 26 Nov 2021 00:16

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Contributors

Author: Xiang Li
Author: Kui-Dong Zhao
Author: Shao-Yong Jiang
Author: Martin Palmer

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