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TitleCharacteristics of diagenetic and epigenetic sulphides in deformed and metamorphosed Archean carbonaceous metasedimentary rocks of the Timmins-Matheson corridor: establishing a framework for fingerprinting ore-forming processes in shear zone-hosted orogenic gold systems
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AuthorPilote, J -L; Jackson, S E; Mercier-Langevin, P; Dubé, B; Rhys, D
SourceTargeted Geoscience Initiative: 2018 report of activities; by Rogers, N (ed.); Geological Survey of Canada, Open File 8549, 2019 p. 33-41, (Open Access)
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Rogers, N; (2019). Targeted Geoscience Initiative: 2018 report of activities, Geological Survey of Canada, Open File 8549
File formatpdf
NTS31M/13; 32D/04; 32D/05; 32D/12; 32D/13; 32E/04; 41P/13; 41P/14; 41P/15; 41P/16; 42A; 42H/01; 42H/02; 42H/03; 42H/04
AreaTimmins; Matheson
Lat/Long WENS -81.5500 -79.6500 49.2167 47.8333
Subjectseconomic geology; tectonics; geochemistry; mineralogy; mineral deposits; gold; sulphide deposits; epigenetic deposits; mineral exploration; ore mineral genesis; mineralization; ore controls; mineral enrichment; tectonic setting; tectonic history; deformation; metamorphism; hydrothermal systems; intrusions; bedrock geology; lithology; metamorphic rocks; metasedimentary rocks; carbonate rocks; argillites; greywackes; igneous rocks; intrusive rocks; structural features; shear zones; nodules; textural analyses; fluid dynamics; scanning electron microscope analyses; mass spectrometer analysis; petrographic analyses; geochemical analyses; trace element analyses; morphology; isotopic studies; Archean; Kidd-munro Assemblage; Tisdale Assemblage; Porcupine Assemblage; Timiskaming Assemblage; Blake River Assemblage; Deloro Assemblage; Stoughton-roquemaure Assemblage; Pacaud Assemblage; Bell Creek Deposit; Bradshaw Deposit; ore systems approach; orogenic gold deposits; diagenetic deposits; Precambrian
Illustrationsgeoscientific sketch maps; photographs; photomicrographs; geochemical plots
ProgramTargeted Geoscience Initiative (TGI-5), Knowledge Management Coordination
ProgramTargeted Geoscience Initiative (TGI-5), Gold ore systems - System Controls - Time and Space
Released2019 03 01
AbstractThis research activity investigates the origin of gold-rich (up to approximately 10 ppm) iron sulphide nodules and the timing of gold introduction in Archean carbonaceous metasedimentary rocks near and distal to orogenic gold mineralization in the Timmins-Matheson area, Ontario. It provides insights into the factors controlling gold enrichment and tests the hypothesis asserting a genetic link between sedimentary sulphides and orogenic gold deposits. Preliminary textural examination of numerous iron sulphide (e.g. pyrite) nodules hosted in various sedimentary sequences from assemblages, including Kidd-Munro, Tisdale, Porcupine, and Timiskaming, reveals evidence of nucleation and formation prior to the main regional deformation events. Pyrite grains that are unequivocally metamorphic/hydrothermal in origin (e.g. coarse-grained euhedral porphyroblasts, overgrowths, and cross-cutting stringers) show distinct geo-chemical signatures compared to the nodules, with lower contents of Sb, Tl, Ag and Au. There are also consistent intra-nodule chemical trends, including, for example, systematic decreases in Au and Ni/Tl from core to rim. These trends are observed across the region, regardless of the setting of the nodules (i.e. shear-hosted, proximal or distal to mineralization, stratigraphic depths). The systematic core to rim decrease in gold content may reflect increasing pH and/or redox potential of the ambient fluid during the development of the nodules. Further geochemical and isotopic work is being conducted to better understand the genesis of the gold-rich nodules and any potential genetic link that may exist between orogenic Au mineralization and an earlier gold enrichment event in the Timmins-Matheson area.