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TitleIdentifying and tracing crustal contamination in the Hart komatiite-associated Ni-Cu-(PGE) deposit using multiple S and Fe isotopes: Abitibi greenstone belt, Ontario
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorHiebert, R S; Bekker, A; Houlé, M G; Rouxel, O J; Wing, B A
SourceTargeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models; by Ames, D EORCID logo (ed.); Houlé, M G (ed.); Geological Survey of Canada, Open File 7856, 2015 p. 197-207, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Targeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models
File formatpdf
Lat/Long WENS -81.5000 -81.0000 48.5000 48.2500
Subjectsmetallic minerals; igneous and metamorphic petrology; isotopes; sulphur; iron; sulphide deposits; Archean; mineralization; komatiites; volcanic rocks; mineral exploration; lithology; modelling; Abitibi Greenstone Belt; Superior Province; Hart deposit; Precambrian
ProgramTargeted Geoscience Initiative (TGI-4) Mafic-Ultramafic Ore Systems
Released2015 06 22; 2023 03 17
AbstractAssimilation by mafic/ultramafic magmas of sulphur-bearing country rocks, typically of sedimentary origin, is commonly considered a critical factor for the genesis of magmatic sulphide deposits. Mass-independent fractionation of sulphur isotopes in the Archean atmosphere produced isotopically distinct pools of S that are recorded in Archean sediments, and can be differentiated easily from mantle sulphur. Likewise, low-temperature processing of iron, potentially including biological and abiotic redox cycling, is also expected to produce Fe isotope values in sediments distinct from the mantle.
The Hart deposit is composed of two mineralized zones; the main zone, a type-I komatiite-associated Ni-Cu-(PGE) sulphide deposit at the base of the basal flow, and the eastern extension, a zone of semi-massive sulphides 12 to 25 m above the base of the second flow within the komatiite sequence. Isotopic characterization, using multiple S and Fe isotopes, of exhalite and graphitic argillite present in the footwall of the mineralization allows tracing the extent of contamination and the degree of mixing within, and adjacent to, the deposit with these potential S sources. This method identifies the exhalite and graphitic argillite as the dominant contaminants for the main zone and the eastern extension mineralization of the Hart deposit, respectively. Additionally, the contamination signature is greatest within the deposit and decreases away from it in the komatiite flow and could potentially be used as a vector towards mineralization. This pattern points also to a local source for crustal contamination of the mantle-derived komatiitic melt and a low degree of homogenization between the mineralization and the surrounding lava flow.
Summary(Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This volume summarizes 22 research activities completed under the TGI-4 Ni-Cu-PGE-Cr ore systems project that focused on revised and new geologic models for Ni-Cu-PGE, PGE-Cu and Cr deposits, innovative techniques for determining potential fertility of intrusion (Ni-Cu-PGE), and defining pathfinders for Ni-Cu-PGE mineralization.

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