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Upper Paleozoic Shale Project

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The North Yukon Upper Palaeozoic Shale Project

This project follows on from the GSC’s Geo-mapping for Energy and Minerals (GEM) project, entitled ‘Yukon Basins Project’, which concluded in 2013 and focused on the understanding of the petroleum potential of Upper Paleozoic strata in Peel Plateau and Eagle Plain basins, particularly the Devonian to Carboniferous fine-grained clastic packages. Stratigraphic units of interest included within this overall project are shales of the: Road River Group, Canol Formation and its western equivalent, the McCann Hill Chert, Ford Lake Shale and Blackie Formation. The study’s geographic area of interest spans the entire north Yukon corridor between Peel Plateau in the east and the far southwestern margins of the Kandik Basin on the Alaskan border. Topics of study include:
• conventional source rock potential – quality and distribution (e.g. derived from RockEval and vitrinite reflectance analyses),
• unconventional reservoir characterisation (e.g. collection of XRD mineralogy, porosity and permeability data, and rock mechanics testing),
• relative biostratigraphic (e.g. palynomorph, conodonts and radiolarians) and absolute chronostratigraphic dating, e.g. U-Pb zircon (from tephra) and δ13C isotope analyses,
• chemostratigraphic correlation and interpretation of depositional environments using whole rock geochemistry data between shale outcrops of the same formation, and also eventually between outcrop and well (cuttings).
• development of a sequence stratigraphic framework for the Upper Palaeozoic, which will also include palaeogeographic interpretation that is also dependent on an understanding of the stratigraphic relationships of these shales with their coarser-grained counterparts, principally the Imperial and Tuttle formations.

Currently there are three main projects being undertaken:

Ford Lake Shale

Canol Formation

“Nick” Horizon Characterisation


Ford Lake Shale

Within the relatively unexplored Peel Plateau and contiguous east flank of the Richardson Mountains, northeast Yukon, Devonian shales mapped as unit ‘Cf’ (Norris, 1981) are little known, but may have the potential to form important conventional source and/or unconventional reservoir targets. The interval is dominated by thick intervals of dark grey to black, siliceous, organic-rich marine shale, together with intercalated siltstone and very fine-grained sandstone beds. Although unit ‘Cf’ has been mapped at surface on the eastern flank of the Richardson Mountains, it is not known whether it occurs in the subsurface to either the east in Peel Plateau or west in Eagle Plain. A correlation of this unit to the Ford Lake Shale (unit ‘CF’ of Norris, 1981), which does occur to the west and into Alaska, has been implied by the mapping nomenclature used historically by geologists in the field.
Initial results from a recently completed, multiyear study on the petroleum potential and stratigraphic affinities of Mississippian-aged shales (unit ‘Cf’) to other Palaeozoic fine-grained units mapped in northern Yukon (e.g. Ford Lake Shale, see Allen et al. in press) demonstrate that the unit has potential as both a source rock and shale oil/gas reservoir, and suggest that these strata have been overlooked as a hydrocarbon target in Yukon’s northern basins. The unit has the following characteristics:
• Type I (oil-prone) and types II & III (oil to gas-prone) kerogen, derived from organic petrology and RockEval pyrolysis respectively,
• A good to very good source rock, with good to very good hydrocarbon generation potential (thermal maturity indices placed these shales within the oil-window),
• A high silica (typically in excess of 90% quartz) and low clay mineral (<7%) content derived from limited XRD analysis, suggesting an ability to respond well to artificial well stimulation techniques.

Using the initial results and recommendations from the recent unit ‘Cf’ study, and working within the objectives set out under the North Yukon Shale Project, YGS aims to conduct the following future work on the Ford Lake Shale interval. Further details on these projects can be found here.
• A re-examination of Famennian to Tournaisian stratigraphy using a sequence stratigraphic framework,
• A more detailed, systematic study of some of the sections initially visited in the multiyear study,
• Further characterization for unconventional (shale gas/oil) reservoir potential.

For more information: Tiffani Fraser


Canol Formation

The Canol Formation is a Middle-Upper Devonian siliceous and organic-rich black shale that is present in Northwest Territories and Yukon. It is a well-known hydrocarbon source rock in north Yukon, but its potential as an unconventional reservoir in this area is unknown.

In 2013, YGS initiated a field-based geoscience study on the Canol Formation and other shale units as part of the ‘Upper Paleozoic Shale Project’.  Goals of the project include:

• Geological characterisation of the Canol Formation including determination of mineralogy, lithogeochemistry, and gamma-radioactivity, and how these factors change over time and space;
• age determination of Canol Formation and over/underlying sediments using biostratigraphy and carbon-isotopes;
• determination of Canol Formation distribution in Yukon;
• correlation of the Canol Formation and age-equivalent strata to adjacent jurisdictions including Alaska, Northwest Territories and British Columbia;
• interpretation of the regional paleo-environment at the time of Canol Formation deposition; and
• hydrocarbon assessment of the Canol Formation as a conventional source rock and an unconventional reservoir.

2013 fieldwork on a near-complete exposure of Canol Formation outcrop in Richardson Mountains is summarized in:

Fraser, T., 2014. Field descriptions of the Middle-Upper Devonian Canol Formation on Trail River, east Richardson Mountains, Yukon. In: Yukon Exploration and Geology 2013, K.E. MacFarlane, M.G. Nordling, and P.J. Sack (eds.), Yukon Geological Survey, p. 53-68.

For more information contact: Tiffani Fraser


“Nick” Horizon Characterisation

Hulbert et al., (1992) identified elevated nickel, zinc and platinum-group element (Ni-Zn-PGE) mineralization at the contact between the Ordovician-Siluran Road River Group limestone and shale and Middle-Upper Devonian Earn Group shale over a >80 km2 regional area in central Yukon. Elevated levels of Se, As, Mo, P, Ba, and U were also observed at this horizon. Proposed theories on the origin of this mineralising event include hydrothermal seafloor venting (Hulbert et al., (1992), and meteorite debris (Goodfellow et al., 2010 ). YGS is interested in evaluating the use of this horizon as a regional marker bed to correlate shales from northern Yukon to the southern Western Canadian Sedimentary Basin and understanding its significance with respect to regional tectonic events.
Specifically this study aims to:
• geologically characterise the sediments hosting/surrounding the Ni-Zn-PGE mineralization including determination of mineralogy, lithogeochemistry and gamma-radioactivity;
• date the Ni-Zn-PGE mineralization using Re-Os isotopes;
• date the underlying Road River Gp and overlying Earn Gp sediments using carbon isotopes and biostratigraphy;
• provide a stratigraphic framework,  depositional history and tectonic setting for the sediments; and
• correlate the Ni-Zn-PGE mineralization event and/or encompassing shale regionally, ideally to northeastern British Columbia, using lithogeochemical tools.

For more information contact Tiffani Fraser 

References:

Goodfellow, W.D., Geldsetzer,H.,  Gregoire, C., Orchard, M., and Cordey, F., 2010.  TGI-3 Workshop: Public geoscience in support of base metal exploration programme and abstracts; by Geological Association of Canada, Cordilleran Section; 2010; p. 15-18. 

 Hulbert, L.J., Gregoire, D.C., Paktunc, D., and Carnes, R.C.,1992. Sedimentary nickel, zinc, and platinum-group element mineralization in Devonian black shales at the Nick Property, Yukon, Canada: a new deposit type.Exploration Mining Geology, vol. 1, p. 39-62.