| Title | Reconnaissance thallium isotope study of zinc-lead SEDEX mineralization and host rocks in the Howard's Pass district, Selwyn Basin, Yukon: potential application to paleoredox determinations and
fingerprinting of mineralization |
| Download | Download (whole publication) |
| Author | Peter, J M; Gadd, M G; Layton-Matthews, D; Voinot, A |
| Source | Targeted Geoscience Initiative: 2017 report of activities, volume 1; by Rogers, N (ed.); Geological Survey of Canada, Open File 8358, 2018 p. 173-191, https://doi.org/10.4095/306474 (Open Access) |
| Year | 2018 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | This publication is contained in Rogers, N; (2018). Targeted
Geoscience Initiative: 2017 report of activities, volume 1, Geological Survey of Canada, Open File 8358 |
| File format | pdf |
| Province | Yukon; Northwest Territories |
| NTS | 105I |
| Area | Howard's Pass |
| Lat/Long WENS | -130.0000 -128.0000 63.0000 62.0000 |
| Subjects | economic geology; tectonics; geochemistry; stratigraphy; paleontology; mineral deposits; mineral exploration; mineral potential; zinc; lead; sedimentary ore deposits; volcanic exhalitive zone;
volcano-sedimentary ore deposits; hydrothermal deposits; ore mineral genesis; mineralization; ore controls; oxidation; isotopic studies; stable isotope studies; hydrothermal systems; marine environments; bedrock geology; lithology; sedimentary rocks;
mudstones; shales; sandstones; cherts; carbonates; dolomites; limestones; igneous rocks; volcanic rocks; volcano-sedimentary strata; sulphides; intrusive rocks; monzonites; granites; source rocks; host rocks; tectonic setting; structural features;
faults; models; bulk composition; geochemical analyses; thallium geochemistry; mass spectrometer analysis; drill core analyses; micropaleontology; microfossils; conodonts; biostratigraphy; Selwyn Basin; Road River Group; Duo Lake Formation; Earn
Group; Mackenzie Platform; Anniv East Deposit; ore systems approach; sedimentary exhalative (SEDEX) deposits; redox indicators; paleoredox indicators; thallium; rare earth element (REE) analyses; chemostratigraphy; Phanerozoic; Mesozoic; Cretaceous;
Triassic; Paleozoic; Carboniferous; Devonian; Silurian; Ordovician; Cambrian; Precambrian; Proterozoic |
| Illustrations | schematic models; bar graphs; tables; geoscientific sketch maps; stratigraphic charts; photographs; geochemical plots; geochemical profiles |
| Program | Knowledge Management Coordination, Targeted Geoscience Initiative (TGI-5) |
| Program | Volcanic and sedimentary systems, Targeted Geoscience Initiative (TGI-5) |
| Released | 2018 01 19 |
| Abstract | The commonly accepted genetic model for sedimentary exhalative (SEDEX) lead-zinc deposits requires a marine basin with anoxic (no oxygen) and euxinic (free H2S) conditions, in order to provide sulphur
to bond with the metals. Recent work on the largest SEDEX district in Canada, the Howard's Pass district, Selwyn Basin, Yukon, has cast doubt on the universality of this model, as the water column may have been suboxic during mineralization.
Paleoredox indicators based on bulk geochemical compositions can be contradictory or equivocal. Developments in non-traditional metal stable isotope analysis have shown the potential of certain isotope systems (e.g. molybdenum, uranium, thallium) as
paleoredox indicators.
We have conducted a bulk geochemical and thallium isotopic traverse through a mineralized intersection (and immediate stratigraphic footwall and hanging wall) from the Anniv East vent-distal SEDEX deposit, Howard's Pass
district. The epsilon-205Tl values range from -7.5 to -4.0 for unmineralized samples and -3.6 to -2.6 for mineralized ones. There is good general agreement between certain redox sensitive elements, venerable redox indicators and epsilon-205Tl for the
unmineralized host rocks (reflecting suboxic or oxic conditions for the most negative values). Thus, the application of thallium isotopes as a redox indicator in seafloor hydrothermal deposits in sedimentary (or volcano-sedimentary) settings shows
great promise. The heaviest values are for mineralized samples, likely reflecting contributions of isotopically heavy thallium from the mineralizing fluids. Preliminary data indicate that thallium isotopes as a redox indicator in mineralized samples
is untenable, but it has the potential to fingerprint sulphides precipitated by various processes. |
| GEOSCAN ID | 306474 |
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