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1. Kluane Ranges
Steve Israel
Yukon Geological Survey
The Kluane Ranges bedrock mapping project is a multi-year, regional-scale mapping program initiated in 2004. The focus of the project is to determine the geological history of the area with emphasis on the structural evolution and stratigraphic relationships of Wrangellia, a late Paleozoic through Mesozoic volcanic and sedimentary terrane located between the Alexander Terrane and the Denali Fault in southwest Yukon.
The Kluane Ranges encompass an area with high mineral exploration potential that includes ultramafic-hosted nickel-copper-platinum group elements (Ni-Cu-PGE), copper-gold skarn and copper-silver vein mineralization. Pennsylvanian to Permian arc volcanic rocks and overlying Permian sedimentary rocks of the Skolai Group comprise the base of exposed Wrangellia and include the Station Creek and Hasen Creek formations, respectively. Intruding near the transitional contact between the Station Creek and Hasen Creek formations are Triassic mafic-ultramafic sills that are host to significant Ni-Cu-PGE mineralization. The sills comprise the Kluane mafic-ultramafic complex, and are thought to be part of a sub-volcanic system that feeds the Middle to Upper Triassic volcanic rocks of the Nikolai formation. The Kluane mafic-ultramafic complex has distinct similarities to intrusions that host some of the world's richest Ni-Cu-PGE ore deposits such as those found in the Noril'sk-Talnakh region in Russia. Significant deposits within the Kluane Ranges include the Wellgreen (Yukon MINFILE 115G 024, Deklerk and Traynor, 2004), with probable reserves calculated at 42 326 323 tonnes grading 0.36% Ni, 0.35% Cu, 0.51 g/t Pt and 0.34 g/t Pd.
Work thus far has uncovered a complex structural story that involves several phases of deformation. Pre-mid Cretaceous contraction is responsible for folding and faulting of the Paleozoic to Mesozoic strata. This event is overprinted by at least two subsequent younger events that include strike-slip faulting (likely related to the Denali Fault) and another phase of contraction that places Triassic rocks over Tertiary sedimentary rocks, and folds Miocene volcanic strata.
Mapping in 2004 covered the area around the Quill Creek and the Wellgreen deposit. This was expanded to the southeast in 2005 to cover much of the Kluane Ranges between southern Kluane Lake and the Donjek River. During the next several summers, work will progress across the Donjek River and eventually cover the entire belt to the Alaska-Yukon border.
References
Deklerk, R. and Traynor, S., 2004. Yukon MINFILE - a database of mineral occurrences (Map 115F/G). Yukon Geological Survey, CD-ROM.
Greene, A.R., Scoates, J.S., Weis, D. and Israel, S., 2005. Flood basalts of the Wrangellia Terrane, southwest Yukon: Implications for the formation of oceanic plateaus, continental crust and Ni-Cu-PGE mineralization. In: Yukon Exploration and Geology 2004, D.S. Emond, L.L. Lewis and G.D. Bradshaw (eds.), Yukon Geological Survey, p. 109-120.
Israel S. and Van Zeyl, D.P., 2005. Preliminary geology of the Quill Creek map area, southwest Yukon parts of NTS 115G/5, 6 and 12. In: Yukon Exploration and Geology 2004, D.S. Emond, L.L. Lewis and G.D. Bradshaw (eds.), Yukon Geological Survey, p. 129-146.
Israel, S. and Van Zeyl, D.P., 2005. Preliminary geological map of the Quill Creek area, (parts of NTS 115G/5, 6, 12), southwest Yukon (1: 50 000 scale). Yukon Geological Survey, Open File 2004-20.