Geology and Coal Resources of the Dominion Coal Block (NTS 082G)
Paper 1989 - 4
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The objectives of paper 1989-4 are to summarize available geological and coal quality information within the Dominion Coal Block, and to present newly developed computer models of the geology of the Coal Block, along with resource calculations derived from the models.
The coal-bearing Mist Mountain Formation of the Jurassic-Cretaceous Kootenay Group crops out in three general areas within the Dominion Coal Block: i) the western half or Parcel 73 on the north end of Hosmer Ridge and the south end of Sparwood Ridge; ii) the southwestern edge of Parcel 82 on Flathead Ridge; iii) the northeastern part of Parcel 82 in the vicinity of Mount Taylor.
Potentially economic coal occurrences in Parcel 73 are in the hangingwall of the Lookout thrust fault. Rocks in this structural block are essentially monoclinal, with a mean bedding orientation of 182 degrees/13.5 degrees (dip-direction/dip). Seven seams are found within a stratigraphic section between 475 and 500 metres in thickness. The major seam, 9-seam or Lookout seam, is near the base of the section, and has a combined thickness of 19 metres in three separate benches. Coals are medium to high volatile bituminous in rank, and for a given stratigraphic position are somewhat lower in rank than those in the surrounding areas. The deposit contains in situ resources of 76 million tonnes at an overall waste-to-coal ratio of 4.7:1 bank cubic metres per tonne. Open pit mining of Parcel 73 appears to be feasible.
Coal occurrences on Flathead Ridge in Parcel 82 are on the west limb or the McEvoy syncline. The structure of the upper part of the Mist Mountain Formation, the only portion of the section modeled here, is monoclinal with an average bedding orientation of 040 degrees/20 degrees. Ten seams occur within a section approximately 400 metres in thickness. A and B-seams, at the top of the Mist Mountain Formation, were the focus of most exploration efforts and of our model. Coals on Flathead Ridge are medium and low-volatile bituminous in rank, and this area in general contains coals of higher rank for a given stratigraphic position than any other part of southeastern British Columbia. Both A and B-seams contain, for the most part, very high quality medium to low-volatile coking coal. Seams lower in the section are of lower quality, including some that have only thermal potential. The deposit, consisting of A and B-seams and their associated riders, contains 230 million tonnes of in situ coal, 17.5 million tonnes of which falls into the measured category. Underground mining is probably the only feasible approach to exploiting the bulk of this resource.
Coal occurrences on Mount Taylor in Parcel 82 are affected by complex structural geology, including north-trending folds and low-angle normal faults. The 400-metre thick stratigraphic section contains 10 coal seams, the thickness of the widest, the U2-seam, ranges from 5.5 to 11 metres. Coal rank varies from medium to high-volatile bituminous, with one small zone of low-volatile rank. The deposit model, which is based on the five thickest seams, predicts in situ coal resources of 613 million tonnes, but identifies no sites with significant open pit mine potential.
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