The northern termination of the Cache Creek terrane in Yukon: Middle Triassic arc activity and Jurassic-Cretaceous structural imbrication

• Main Authors: Bickerton, Luke, Colpron, Maurice, Gibson, Dan, Thorkelson, Derek J., Crowley, James L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2019
• Subjects: Yukon; Judas; Judas Mountain; Mount Michie; Whitehorse
• Online Access: http://hdl.handle.net/1807/98820; http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2018-0262

The northernmost part of the Cache Creek terrane lies in south-central Yukon and comprises metavolcanic rocks, hemipelagic chert and shale, newly identified volcaniclastic and clastic rocks (Michie formation, informal), pyroxenite and gabbro intrusive rocks with an arc to back-arc geochemical signature, as well as tectonized and serpentinized ultramafic rocks. The proximally sourced Michie formation yielded zircon from two samples with unimodal peaks at 245.85 ± 0.07 and 244.64 ± 0.08 Ma. These dates are likely close to the depositional ages and compare favourably with those from the Kutcho assemblage of northern British Columbia. The Michie formation is exposed along the northwestern flank of Mount Michie and represents singular detrital input from a nearby eroding island-arc. The Cache Creek terrane rocks are imbricated with epiclastic and carbonate rocks of the Stikinia and Lower Jurassic siliciclastic rocks of the synorogenic Whitehorse trough. This imbrication records two compressional deformation phases in the region: (1) an initial phase of west-verging thrusting along the Judas Mountain fault that placed the Cache Creek terrane rocks over the arc and basinal rocks of Stikinia and Whitehorse trough; and (2) a second phase of east-verging thrusting along the Mount Michie fault that repositioned rocks of Stikinia and the Whitehorse trough structurally above those of the Cache Creek terrane. Deformation in the centre of the study area was followed by emplacement of a coarse-grained syenite that yielded 40Ar/39Ar biotite and muscovite cooling ages of 165–160 Ma. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.