| Title | Structural style of the Kootenay Group, with particular reference to the Mist Mountain Formation on Grassy Mountain, Alberta |
| Download | Downloads |
| Author | Norris, D K |
| Source | Geological Survey of Canada, Bulletin 449, 1994, 42 pages (1 sheet), https://doi.org/10.4095/194012 |
| Year | 1994 |
| Publisher | Natural Resources Canada |
| Document | serial |
| Lang. | English |
| Maps | Publication contains 1 map |
| Map Info. | geological, structural, lithological, 1:8,000 |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Alberta |
| NTS | 82H/09 |
| Area | Grassy Mountain; Blairmore; Front Ranges; Rocky Mountains |
| Lat/Long WENS | -115.0000 -114.0000 49.7500 49.2500 |
| Subjects | structural geology; fossil fuels; structural interpretations; structural analyses; imbrication; open pits; faults; faults, thrust; folds; shearing; structural features; coal; coal seams; bituminous
coal; hydrocarbons; Upper Jurassic; stratigraphic correlations; Kootenay Group; Mist Mountain Formation; Laramide Orogeny; Cretaceous; Jurassic |
| Illustrations | sketch maps; photographs; cross-sections |
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| Released | 1994 05 01; 2015 11 18 |
| Abstract | Grassy Mountain, eight kilometres north of Blairmore, Alberta, lies within the Livingstone Thrust plate in the Front Ranges of the Rocky Mountains. On the mountain, strata of the Kootenay Group are
highly sheared, thrust faulted, and cylindrically folded. Of the four coal seams contained within the Mist Mountain Formation of the Kootenay Group, the second highest, or No. 2 Seam, has been and will be the greatest resource on the mountain.
Continuous exposures in the abandoned open-pit mines, as well as the many coal prospects in the No. 2 Seam, reveal two fundamental mechanisms by which the coal has been tectonically repeated, thickened, and thinned. These mechanisms are: imbrication,
resulting in layer-parallel piling up of the coal and associated roof and floor rock; and flow, resulting in mass transport of the coal on a profusion of discrete slip surfaces from one part of a seam to another. Imbrication does not necessarily rob
the coal from immediately adjacent areas; flow does. These shearing mechanisms are end members of a continuum of structural styles that resulted in the progressive destruction of the primary depositional fabric of the seams as well as in the
detachment of the seams from their roofs and floors. Imbrication and flow were concurrent responses to the same regional compressive forces of the Laramide Orogeny in the latest Cretaceous and early Tertiary. Imbrication made the Kootenay Group coals
accessible to exploitation in numerous places, but also introduced structural complications that degraded the coals and limited the capacity of simple geological models to predict the presence of mineable coals at depth. The resource potential for
medium volatile bituminous coal on Grassy Mountain is vast, and is largely confined to the No. 2 Seam. |
| GEOSCAN ID | 194012 |
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