The Mount Jackson occurrence comprises coal showings found on Mount Jackson, Jackson Flats and McEvoy Flats, 1.6 kilometres due south of the junction between Currier Creek and the Skeena River, about 145 kilometres northeast of the community of Stewart.
These showings form part of the southeast Groundhog coalfield, an oblong (roughly 30 by 80 kilometres) area extending from the headwaters of the Klappan and Little Klappan rivers southeast to Groundhog Mountain. Refer to the Discovery deposit (104A 078), located 5 kilometres northwest, for an overview on the exploration history, regional geology and local geology of the southeast Groundhog coalfield.
The coal seams form part of the Lower Cretaceous Currier Formation (Bowser Lake Group, Muskaboo Creek assemblage) comprising carbonaceous shale, siltstone and sandstone. Multiple coal seams have been documented (Coal Assessment Report 98) on the upper north slope of Mount Jackson (8 to 10 seams), in the lower reaches of Trail and Jackson creeks (6 seams each), Little Creek (3 seams), Falconer Creek and Abraham Creek. Seam widths vary from 0.5 to 3.0 metres thick. Approximately 45 samples were collected between 1982 and 1983, the coal quality analyses varied widely (Coal Assessment Reports 107, 108):
--------------------------------------------------------------------- Range for Raw Coal Fixed carbon 12 - 89 Ash Content 7 - 84 Volatile matter 4 - 23 Calorific value 800 - 7720 --------------------------------------------------------------------- |
All values are in per cent except for the calorific value which is in calories per gram. Coal rank varies from anthracite to meta-anthracite.
A single diamond-drill hole in the McEvoy Flats near Abraham Creek intersected 10 coal seams for an aggregate thickness of 6.25 metres (Coal Assessment Report 98). Coal quality testing of the two thickest seams (each exceeding 1.5 metres) gave the following values:
------------------------------------------------------------------------------- Upper Seam Lower Seam Float yield 55.7 69.7 Fixed carbon 70.8 80.6 Ash content 19.8 12.5 Volatile Matter 9.5 6.9 Sulphur content 0.7 0.9 Calorific value 6526 7193 ------------------------------------------------------------------------------- |
The float yield is based on a specific gravity separation of 1.75 grams per cubic centimetre.
In 1970, a joint venture between National Coal Corporation Ltd., Placer Development Ltd., and Quintana Minerals Corporation conducted geological mapping and drilling of six boreholes totalling 1029 metres.
Suncor was active in the Mount Jackson area in the early 1980s, opening 50 trenches. In 1988, Gulf Canada conducted trenching, measuring of sections, mapping and sampling at Mount Jackson.
The nomenclature of the coal-bearing rock units in the Mount Klappan area has a complex history. It has been variously referred to as the Currier Formation (Bustin and Moffat, Canadian Society of Petroleum Geologists Bulletin 1983; Macleod and Hills, Canadian Journal of Earth Sciences 1990, and most industry Coal Assessment Reports), the Groundhog-Gunanoot facies (Eisbacher, Geological Survey of Canada Paper 73-33), the Gunanoot assemblage (Richards and Gilchrist, Geological Survey of CanadaPaper 79-1B), and the Groundhog-Gunanoot assemblage (Evenchick and Thorkelson, Geological Survey of Canada Bulletin 577, (2005)). Evenchick and Thorkelson (Geological Survey of Canada Bulletin 577) provide a history of stratigraphic nomenclature in the coalfield, and a discussion of the debate over the age of the coal-bearing unit, which they refer to as the Groundhog-Gunanoot assemblage. The age is not well-constrained, and may vary by area; however, it is mainly between latest Jurassic and late Early Cretaceous.
