Abstract: The Cenomanian-Turonian (Upper Cretaceous) Boundary Creek Formation is a mudstone, shale and silty shale unit that is exposed in river and creek cuts on Yukon’s North Slope. As part of the CASE-15 expedition, co-led by the Yukon Geological Survey and the German Federal Institute for Geosciences and Natural Resources, fieldwork in July 2013 involved measuring and sampling Boundary Creek Formation strata in two locations, and investigating a burning shale exposure near the confluence of Boundary Creek and the Big Fish River. Shale and mudstone samples were analyzed for XRF lithogeochemistry and organic matter quantity, along with thermal maturity and type using RockEval/TOC and vitrinite reflectance techniques. The Boundary Creek Formation is interpreted to have been deposited by turbidity currents moving through an outer shelf to slope environment in the distal part of the foreland basin, outboard of the Cordilleran orogeny. Lithogeochemical data suggest that at times throughout the deposition of Boundary Creek Formation shale, ocean water may have been depleted in oxygen, resulting in anoxic conditions that would have been favourable for organic matter preservation. Analyses of surface samples suggest that some areas have poor to no petroleum potential and are thermally overmature with respect to oil generation. In others, good to very good petroleum potential exists and the shale is oil to oil and gas prone and thermally mature with respect to oil generation. In these latter areas, specifically in the vicinity of the type section on Boundary Creek, the shale has the necessary components for spontaneous combustion: pyrite, organic matter and a fresh supply of oxygen provided by a landslide. Although burning shale is not unknown in northern Canada, the outcrop of burning shale on Yukon’s North Slope is the first observed in shale of the Upper Cretaceous Boundary Creek Formation.

Authors: Fraser, T.A. and Reinhardt, L.

Citation: Fraser, T.A. and Reinhardt, L., 2015. Stratigraphy, geochemistry and source rock potential of the Boundary Creek Formation, North Slope, Yukon and a description of its burning shale locality. In: Yukon Exploration and Geology 2014, K.E. MacFarlane, M.G. Nordling and P.J. Sack (eds.), Yukon Geological Survey, p. 45-71.

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