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TitleSuperimposed auriferous structural events along the Llewellyn-Tally Ho deformation corridor in southern Yukon and northwest British Columbia
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AuthorOotes, L; Castonguay, S; Friedman, R; Devine, F
SourceTargeted Geoscience Initiative: 2018 report of activities; by Rogers, N (ed.); Geological Survey of Canada, Open File 8549, 2019 p. 49-58, (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
ProvinceYukon; British Columbia
NTS104M/07; 104M/08; 104M/09; 104M/10; 104M/11; 104M/12; 104M/13; 104M/14; 104M/15; 104M/16; 105D/01; 105D/02; 105D/03; 105D/04; 105D/05; 105D/06; 105D/07; 105D/08
AreaMount Hodnett; Tally Ho Mountain; Annie Lake; Wheaton River; Engineer; Montana Mountain; Mount Skukum; Tutshi Lake; Moon Lake; Racine Lake; Taglish lake; Bennett Lake; Middle Ridge
Lat/Long WENS-135.5833 -134.0000 60.3667 59.2500
Subjectseconomic geology; structural geology; tectonics; geochronology; mineral deposits; gold; mineral exploration; epithermal deposits; mesothermal deposits; ore mineral genesis; mineralization; ore controls; structural controls; tectonic history; deformation; foliation; mylonites; lineations; intrusions; plutons; dykes; bedrock geology; structural features; faults; shear zones; lithology; igneous rocks; intrusive rocks; granodiorites; volcanic rocks; sedimentary rocks; metamorphic rocks; radiometric dating; uranium lead dating; zircon dates; mineral occurrences; Llewellyn Fault; Tally-Ho Shear Zone; Nisling Terrane; Stikinia Terrane; Tintina Gold Belt; Juneau Gold Camp; Sloko Group; Windy Table Coplex; Carmacks Group; Stuhini Group; Laberge Group; Boundary Ranges Metamorphic Suite; Whitehorse Plutonic Suite; Bennett Granite; Lewes River Group; Povoas Formation; orogenic gold deposits; intrusion-related deposits; Phanerozoic; Cenozoic; Tertiary; Mesozoic; Cretaceous
Illustrationslocation maps; geoscientific sketch maps; tables; photographs; cross-sections; geological time charts
ProgramTargeted Geoscience Initiative (TGI-5), Knowledge Management Coordination
ProgramTargeted Geoscience Initiative (TGI-5), Gold ore systems - tectonic drivers and conduits
Released2019 03 01
AbstractThe Llewellyn-Tally Ho deformation zone in northwest British Columbia and southern Yukon demarcates the eastern limit of the Nisling terrane and the western limit of the Stikine terrane and has spatially related epithermal, mesothermal, and intrusion-related gold deposits and occurrences. The Llewellyn fault is a southeast-striking, steeply dipping brittle dextral strike-slip structure that overprints 'early' penetrative fabrics and ductile deformation. The Tally Ho shear zone, in the Yukon, represents an early ductile deformation zone, comprising one penetrative foliation (Smain) and mylonite zones that are overprinted by late brittle faulting, analogous to the Llewellyn fault. Previous work and this study demonstrate that brittle strike-slip deformation along the Llewellyn fault occurred between ca. 56 and 50 Ma. Two granodiorite intrusions (ca. 75 Ma) crosscut the early ductile deformation fabrics. In the Tally Ho shear zone, Smain crosscuts a granodiorite pluton and porphyry dyke, which have yielded preliminary U-Pb zircon dates of ca. 98 and 95 Ma, respectively. As such, we infer that the early ductile fabrics formed before ca. 75 Ma and after ca. 95 Ma. This study further demonstrates that the early ductile and late brittle deformation are separated by at least ca. 20 Ma, indicating the various styles of gold mineralization developed during temporally distinct tectonic events: an 'early' late Cretaceous ductile event typical of the Tintina gold belt; and a 'later' Eocene brittle event matching the timing and structural framework of the Juneau gold camp.