Abstract: New geochronological and geochemical data from the ‘Windy-McKinley’* terrane provide insight into the age, correlation and paleotectonic settings of the various subdivisions of the terrane. U-Pb zircon age determinations for felsic meta-volcanic rocks of the White River formation and gabbro intrusions are Late Devonian and late Middle Triassic respectively. These new age determinations substantiate the proposed correlation of these components of ‘Windy-McKinley’ terrane with the succession on strike to the northwest which hosts the volcanogenic massive sulphide deposits in the Delta District, Alaska. Trace-element geochemical data from Triassic gabbro intrusions into the Mirror Creek and White River formations, and diabase and gabbro of the Harzburgite Peak-Eikland Mountain ophiolite suggest that magmatism in both subdivisions occurred in supra-subduction zone settings. However, the age of the ophiolite is not known, therefore mafic magmatism may not be coeval across the terrane and may have formed above different subduction zones at different times.
*Quotes are used to indicate that the assignment to Windy and McKinley terranes is obsolete, but a new name has not yet been assigned.

Authors: Murphy, D.C., Mortensen, J.K. and van Staal, C.

Keywords: geochemistry, geochronology, Mirror Creek formation, White River formation, Zircon dating

NTS Mapsheet(s): 115F, 115G, 115J, 115K

Citation: Murphy, D.C., Mortensen, J.K. and van Staal, C., 2009. ‘Windy-McKinley’ terrane, western Yukon: new data bearing on its composition, age, correlation and paleotectonic settings. In: Yukon Exploration and Geology 2008, L.H. Weston, L.R. Blackburn and L.L. Lewis (eds.), Yukon Geological Survey, p. 195-210.

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