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TitleA Middle Devonian basin-scale precious metal enrichment event across north Yukon (Canada)
AuthorGadd, M GORCID logo; Peter, J MORCID logo; Hnatyshin, D; Creaser, R A; Gouwy, SORCID logo; Fraser, T
SourceGeology vol. 48, no. 3, 2020 p. 242-246, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190272
PublisherGeological Society of America
Mediapaper; on-line; digital
File formatpdf
NTS106; 116A; 116B; 116G; 116H; 116I; 116J; 116O; 116P
AreaRichardson Mountains; Ogilvie River; Yukon River
Lat/Long WENS-140.0000 -128.0000 68.0000 64.0000
Subjectsgeochronology; stratigraphy; sedimentology; Middle Devonian; mineral enrichment; black shales; biostratigraphy; isochrons; mineral deposits; precious metals; nickel; molybdenum; zinc; platinum; palladium; gold; sulphide deposits; ore mineral genesis; mineral enrichment; host rocks; bedrock geology; Canol Formation; Canadian Cordillera; Richardson Trough; Road River Group; Nick prospect; Peel River showing; Devonian; Paleozoic
Illustrationslocation maps; stratigraphic columns; plots
ProgramTargeted Geoscience Initiative (TGI-5) Volcanic and sedimentary systems - volcanogenic massive sulphide ore systems
Released2020 01 03
AbstractHyper-enriched black shale (HEBS) Ni-Mo-Zn-Pt-Pd-Au-Re mineralization is geographically widespread across the Richardson trough in northern Yukon (Canada), where it discontinuously outcrops at the regional contact between the Road River Group and overlying Canol Formation. Stratigraphic relationships indicate that the contact is Middle Devonian, but there are no precise age constraints for the HEBS. We apply Re-Os geochronology to HEBS mineralization from two localities that are 130 km apart, the Nick prospect and the Peel River showing, to date directly the age of sulfide mineralization. The Nick prospect yields an isochron age of 390.7 ± 5.1 (2o) Ma, whereas the Peel River showing yields an isochron age of 387.5 ± 4.4 (2o) Ma. Within error, these ages are identical and overlap with the biostratigraphically constrained age of the sedimentary host rocks, indicating that mineralization and sedimentation were coeval. Significantly, the ages of the HEBS overlap those of Middle Devonian Kacák, pumilio, and Taghanic global-scale biotic events which are characterized by eustatic sea-level rise and black shale deposition. Linkage of the Yukon HEBS to one (or more) of these bio-events indicates that sea-level rise may have been requisite to formation of basin-scale HEBS mineralization in northwestern Canada during latest Eifelian and Givetian time.
Summary(Plain Language Summary, not published)
This work applies Re-Os geochronology to metal-rich shale in north Yukon in an attempt to constrain precisely the age of the metal-enriching event. The data support the hypothesis that enrichment and sedimentation were concurrent at approximately 400 million years ago. This is the first research to constrain the age of mineralization in these deposits. The work is highly relevant to any exploration geologists and economic geologists interested in gaining a better understanding about how and when these enigmatic deposits formed.

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