"The Bridge" from Earthscope to EarthsCAN
Katherine Boggs, Mount Royal University
Maurice Colpron, Yukon Geological Survey
Julie Elliot, Purdue University
Roy Hyndman, Pacific Geoscience Centre (GSC), University of Victoria
Kristin Morell, University of Victoria
"The Bridge" is one possible proof of concept for the new EarthsCAN research initiative in the Yukon Territories. The proposal is to fill gaps between the Earthscope Transportable Array seismic stations being installed from 2015 to 2017, the McKenzie Mtn Earthscope Project (MMEP; Schutt et al), seismic sites installed or being installed by the Geological Survey of Canada, the Yukon Geological Survey, Universities of Ottawa and Calgary as well as other industry/government consortia. This concept would create a bridge of seismic stations from the Pacific Ocean across Alaska and the Yukon to the Beaufort Sea. It would also maintain scientific momentum in North America by providing a bridge between Earthscope and EarthsCAN. A recent workshop in Whitehorse provided several appealing and outstanding questions to address in this area of the northern Cordillera. The Yukon Stable Block (YSB) is characterized by a very large magnetic high which is underlain in part by the Paleoproterozoic Wernecke Supergroup (not found anywhere else in the Canadian Cordillera). Cretaceous and Tertiary structures are deflected around the YSB suggesting that there are significantly different crustal compositions and/or thicknesses between the south and the north of the YSB (Colpron). Elliot et al have described complex relative plate motions that are being revealed by GPS observations in Alaska and NW Canada. The previously unrecognized Ellis block is rotating counterclockwise, while the Yakutat block is colliding with North America in a NNW direction, whereas the Alaska panhandle appears to be rotating clockwise into North America. How the resultant strain is being accommodated inland across the McKenzie Mountains is being investigated by the MMEP and the aforementioned agencies. Lidar image analysis and paleoseismic trenching could be used to characterize active faults in the McKenzie Mtns as per the Morell et al study on southern Vancouver Island. There are two other intriguing aspects to the Canadian Cordillera (Hyndman): i) the Yakutat Terrane collision is producing very high coastal mountains and deformation that spreads far inland, a mini Himalayan system; ii) there is a fascinating tectonic transition from the episodic slip and tremors of the young hot Cascadia subduction zone, to the subduction of the Explorer plate, to ridge subduction-slab window and then transition from oblique convergence along the Queen Charlotte Fault under Haida Gwai to pure strike slip motion along the Fairweather Fault in Alaska.