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TitleFluids and ore forming processes in orogenic gold deposits in Newfoundland, eastern Canada: evidence from fluid inclusion and stable isotope studies
AuthorConliffe, J; Sandeman, H A I; Honsberger, I WORCID logo; Guillaume, B; Laflamme, C; Wilton, D
SourceAtlantic Geoscience vol. 59, 2023 p. 76-77, Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20220661
PublisherAtlantic Geoscience
Mediapaper; digital; on-line
File formatpdf
ProvinceNewfoundland and Labrador
SubjectsScience and Technology; metallic minerals; gold; mineral deposits
ProgramTargeted Geoscience Initiative (TGI-6) Ore systems
Released2023 05 03
AbstractNewfoundland is a major emerging gold district containing numerous gold occurrences associated with Paleozoic crustal-scale fault systems. These occurrences have characteristics typical of orogenic gold deposits, such as association with crustal-scale faults, syntectonic rock sequences, and lower greenschist- to amphibolite-facies metamorphism. However, there are significant variations in mineralization styles and settings between individual gold occurrences, including host lithologies, metal associations and sources, and inferred mineralization depths. This study investigates variations in mineralizing fluids and ore-forming processes in central Newfoundland, based on fluid inclusion and preliminary sulphur isotope data from a number of gold occurrences representing a diverse range of geological settings. Fluid inclusion studies have shown that mineralizing fluids are moderate to high temperature (250 to 350°C), low-salinity (< 10 wt% eq. NaCl) aqueous carbonic fluids, which are considered typical of orogenic gold deposits. However, there are significant inter-deposit variations (e.g. XCO2, CO2:CH4) that are likely related to fluid unmixing and the geochemical influence of the host lithologies. Isochoric modelling suggests different depths of mineralization for gold occurrences across central Newfoundland, ranging from relatively shallow epizonal mineralization in the Gander area (e.g. Queensway, Moosehead, Kingsway) to deeper mesozonal mineralization in deposits to the southwest (e.g. Valentine Lake, Wilding Lake). In-situ sulphur isotope analyses of sulphides associated with gold mineralization can provide insights into ore deposition processes as well as the source of sulphur in orogenic gold deposits. Preliminary data from along the central Newfoundland orogenic gold district show significant inter-deposit variability. Future research will include more fluid inclusion studies along with in situ sulfur isotope and trace element analyses, which will be used to better constrain ore fluids, sulphur and metal sources, and gold precipitation mechanisms.
Summary(Plain Language Summary, not published)
This contribution presents new data regarding the source of fluids that precipitated gold throughout central Newfoundland.

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