|Title||Paleoredox and lithogeochemical indicators of the environment of formation and genesis of the Monster River hyper-enriched black shale showing, Yukon|
|Licence||Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences.|
|Author||Gadd, M G; Peter,
J M; Fraser, T A; Layton-Matthews, D|
|Source||Targeted Geoscience Initiative 5: volcanic- and sediment-hosted massive-sulfide deposit genesis and exploration methods; by Peter, J M (ed.); Gadd, M G (ed.); Geological Survey of Canada, Bulletin 617, 2022 p. 113-127, https://doi.org/10.4095/328004
|Publisher||Natural Resources Canada|
|Related||This publication is contained in Targeted Geoscience
Initiative 5: volcanic- and sediment-hosted massive-sulfide deposit genesis and exploration methods |
|Related||NRCan photo(s) in this publication|
|Area||Yukon River; Ogilvie Mountains|
|Lat/Long WENS||-140.5400 -140.5397 64.8350 64.8347|
|Subjects||economic geology; geochemistry; sedimentology; stratigraphy; Science and Technology; Nature and Environment; Middle Devonian; mineral exploration; exploration methods; mineral deposits; sedimentary ore
deposits; nickel; molybdenum; zinc; gold; ore mineral genesis; mineralization; ore controls; paleoenvironment; continental margins; marine environments; sea water geochemistry; depositional environment; sedimentation; lithogeochemistry; trace element
analyses; major element analyses; geochemical anomalies; host rocks; bedrock geology; lithology; sedimentary rocks; shales; metals; sulphur; lithostratigraphy; cerium geochemistry; molybdenum geochemistry; uranium geochemistry; yttrium geochemistry;
Monster River Showing; Yukon Block; Blackstone Trough; Canol Formation; Road River Group; platinum group elements; Phanerozoic; Paleozoic; Devonian|
|Illustrations||location maps; geoscientific sketch maps; lithologic sections; photographs; tables; profiles; plots|
|Program||Targeted Geoscience Initiative (TGI-5) Volcanic and sedimentary systems - volcanogenic massive sulphide ore systems|
|Released||2022 01 27; 2022 11 17|
|Abstract||Northern Yukon hosts occurrences of Middle Devonian hyper-enriched black shale (HEBS) Ni-Mo-Zn-platinum-group element-Au-Re mineralization, including the Monster River showing in the Ogilvie Mountains.
This mineralization has been documented predominantly in the Paleozoic Richardson trough; however, the Monster River showing is atypical, occurring within the Blackstone trough, more than 200 km to the west on the southern margin of the Yukon block.
The ambient paleoredox conditions of the marine water column and sediments may be primary controlling factors in HEBS formation. We use major and trace element lithogeochemistry to better understand ambient paleoenvironmental redox conditions through
the application of robust redox proxies to HEBS mineralization and host rocks. Uniformly negative Ce anomalies (0.6-0.9) indicate that the water column was predominantly suboxic throughout the deposition interval, even during HEBS mineralization.
Although there is a strong terrigenous influence on the rare earth element-yttrium (REE-Y) abundances of the sedimentary rocks, superchondritic Y/Ho ratios (>27) indicate that seawater contributed REE-Y to the host rocks and HEBS. High (>10)
authigenic Mo/U ratios indicate that a Fe-Mn particulate shuttle operated in the water column; this is corroborated by negative Ce anomalies and high Y/Ho ratios. The data indicate that metalliferous sedimentary rocks formed by hydrogenous metal
enrichment (e.g. Ni, Mo, Pt) caused by ferromanganese oxyhydroxide particulate shuttling as chemical sediments; moreover, the REE- and Mo-based paleoenvironmental indicators suggest a complexly redox-stratified depositional environment with an
abundant supply of metals, metalloids, and sulfur. |
|Summary||(Plain Language Summary, not published)|
The Targeted Geoscience Initiative (TGI) 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 contribution summarizes the results of a 5-year study of multiple mineral deposit types: polymetallic hyper-enriched
black shale; sedimentary exhalative Pb-Zn; carbonate-hosted Pb-Zn, magnesite; fracture-controlled replacement Zn-Pb, rare-earth element-F-Ba; and volcanogenic massive sulfides. Studies employed field geology, combined with geochemical
(lithogeochemistry, stable and radiogenic isotopes, fluid inclusions, and mineral chemistry) and geophysical (rock properties, magnetotelluric, and seismic) methods. Collectively, the research provides advanced genetic and exploration models for
volcanic- and sedimentary-hosted base-metal deposits, together with new laboratory, geophysical, and field techniques.