MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada

The Voisey’s Bay nickel-copper-cobalt (Ni-Cu-Co) sulphide deposits constitute a significant resource of orthomagmatic mineralization. The deposits are not exposed at the surface except for in a small ferruginous gossan (Discovery Hill). The subsequent geophysical surveys and diamond drilling led to...

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Autores principales:	Derek H. C. Wilton, Gary M. Thompson, Dawn Evans-Lamswood
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	Voisey’s Bay sulphide oxidation MLA-SEM analysis gossan development indicator minerals paleo-regolith Mineralogy QE351-399.2
Acceso en línea:	https://doaj.org/article/6eae52dfd17d474b969838211afe4090
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spelling	oai:doaj.org-article:6eae52dfd17d474b969838211afe40902021-11-25T18:26:24ZMLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada10.3390/min111112242075-163Xhttps://doaj.org/article/6eae52dfd17d474b969838211afe40902021-11-01T00:00:00Zhttps://www.mdpi.com/2075-163X/11/11/1224https://doaj.org/toc/2075-163XThe Voisey’s Bay nickel-copper-cobalt (Ni-Cu-Co) sulphide deposits constitute a significant resource of orthomagmatic mineralization. The deposits are not exposed at the surface except for in a small ferruginous gossan (Discovery Hill). The subsequent geophysical surveys and diamond drilling led to the discovery of the Ovoid ore body, buried beneath 20 m of till, and other deeper deposits in the bedrock. This study was initiated to characterize the sulphide mineralogy of these deposits through various stages of weathering, erosion, and transport. Because the samples ranged from bedrock through to a variety of surficial sediment types, the automated SEM-based identification provided by the MLA-SEM system was the ideal technique to quantitatively evaluate mineral distributions in the different media. The derived MLA-SEM data indicate that, aside from the Discovery Hill gossan, the surface sulphide mineralization at Voisey’s Bay was weathered in a pre-glaciation regolith at the Mini-Ovoid deposit and, on the surface of the Ovoid deposit, the massive sulphide was unoxidized due to a thin calcite-cemented clay cover. Pentlandite is very preferentially oxidized compared to other sulphides in the Voisey’s Bay ore, to depths of up to 10 m in bedrock. Conversely, within the coarse reject samples of crushed drill cores stored in sealed plastic bags, pyrrhotite was altered, whereas pentlandite and chalcopyrite are stable, presumably due to anaerobic reactions. The MLA-SEM detected trace amounts of minute sulphide grains in surficial sediments, but their contents abruptly decreased with distance from the sulphide mineralization. Microtextures such as troilite and pentlandite exsolution or twinning in pyrrhotite, however, could be observed in the fine sulphide grains from till, suggesting a derivation from orthomagmatic sulphide material, such as the Voisey’s Bay mineralization.Derek H. C. WiltonGary M. ThompsonDawn Evans-LamswoodMDPI AGarticleVoisey’s Baysulphide oxidationMLA-SEM analysisgossan developmentindicator mineralspaleo-regolithMineralogyQE351-399.2ENMinerals, Vol 11, Iss 1224, p 1224 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Voisey’s Bay sulphide oxidation MLA-SEM analysis gossan development indicator minerals paleo-regolith Mineralogy QE351-399.2
spellingShingle	Voisey’s Bay sulphide oxidation MLA-SEM analysis gossan development indicator minerals paleo-regolith Mineralogy QE351-399.2 Derek H. C. Wilton Gary M. Thompson Dawn Evans-Lamswood MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada
description	The Voisey’s Bay nickel-copper-cobalt (Ni-Cu-Co) sulphide deposits constitute a significant resource of orthomagmatic mineralization. The deposits are not exposed at the surface except for in a small ferruginous gossan (Discovery Hill). The subsequent geophysical surveys and diamond drilling led to the discovery of the Ovoid ore body, buried beneath 20 m of till, and other deeper deposits in the bedrock. This study was initiated to characterize the sulphide mineralogy of these deposits through various stages of weathering, erosion, and transport. Because the samples ranged from bedrock through to a variety of surficial sediment types, the automated SEM-based identification provided by the MLA-SEM system was the ideal technique to quantitatively evaluate mineral distributions in the different media. The derived MLA-SEM data indicate that, aside from the Discovery Hill gossan, the surface sulphide mineralization at Voisey’s Bay was weathered in a pre-glaciation regolith at the Mini-Ovoid deposit and, on the surface of the Ovoid deposit, the massive sulphide was unoxidized due to a thin calcite-cemented clay cover. Pentlandite is very preferentially oxidized compared to other sulphides in the Voisey’s Bay ore, to depths of up to 10 m in bedrock. Conversely, within the coarse reject samples of crushed drill cores stored in sealed plastic bags, pyrrhotite was altered, whereas pentlandite and chalcopyrite are stable, presumably due to anaerobic reactions. The MLA-SEM detected trace amounts of minute sulphide grains in surficial sediments, but their contents abruptly decreased with distance from the sulphide mineralization. Microtextures such as troilite and pentlandite exsolution or twinning in pyrrhotite, however, could be observed in the fine sulphide grains from till, suggesting a derivation from orthomagmatic sulphide material, such as the Voisey’s Bay mineralization.
format	article
author	Derek H. C. Wilton Gary M. Thompson Dawn Evans-Lamswood
author_facet	Derek H. C. Wilton Gary M. Thompson Dawn Evans-Lamswood
author_sort	Derek H. C. Wilton
title	MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada
title_short	MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada
title_full	MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada
title_fullStr	MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada
title_full_unstemmed	MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada
title_sort	mla-sem characterization of sulphide weathering, erosion, and transport at the voisey’s bay orthomagmatic ni-cu-co sulphide mineralization, labrador, canada
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/6eae52dfd17d474b969838211afe4090
work_keys_str_mv	AT derekhcwilton mlasemcharacterizationofsulphideweatheringerosionandtransportatthevoiseysbayorthomagmaticnicucosulphidemineralizationlabradorcanada AT garymthompson mlasemcharacterizationofsulphideweatheringerosionandtransportatthevoiseysbayorthomagmaticnicucosulphidemineralizationlabradorcanada AT dawnevanslamswood mlasemcharacterizationofsulphideweatheringerosionandtransportatthevoiseysbayorthomagmaticnicucosulphidemineralizationlabradorcanada
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MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada

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