The anthracite deposits at the Summit, Nass and Skeena prospects are part of the Klappan area of the Groundhog Coalfield near the north end of the Bowser Basin of British Columbia. The Bowser Basin was filled with sediments deposited from eroding mountains during the late Jurassic and early Cretaceous. At the northern end of the basin, peat formation occurred in deltaic environments. These peat bogs were metamorphosed to form the coal-bearing sequences of the Groundhog Coalfield, an oblong (30 by 80 kilometres) area extending southeastwards from the headwaters of the Klappan and Little Klappan rivers to Groundhog Mountain in the Skeena Ranges, an area characterized by mountainous terrain with broad valleys.
The coal-bearing sequences of the Groundhog Coalfield reach approximately 1100 metres in thickness, with 33 identified coal horizons of up to 11.8 metres in true thickness interbedded with primarily mudstone, siltstone and sandstone.
The coal-bearing units and surrounding beds were later deformed by compression that created open to tight folds that are near vertical to overturned to the northeast. Fold axes strike 030 to 060 degrees and axial planes dip 25 to 85 degrees southwest. The folds are cut by thrust faults striking 020 to 040 degrees and dipping 10 to 25 degrees southwest. The whole area is cut by younger high-angle faults trending northwest, north and northeast.
The Mount Klappan area is in the northwest part of the Groundhog Coalfield on mapsheet 104H and hosts several prospects. Interest in the potential of the Mount Klappan area began in 1979. Esso conducted a field program in the summer of 1979 consisting of mapping and sampling on areas around Hobbit Creek and Lost Ridge.
Gulf Canada conducted exploration at the Mount Klappan Project in the 1980s, including the Lost, Fox, Summit, Hobbit-Broatch, Nass and Skeena areas. In total, Gulf drilled over 24,734 metres of diamond drilling in 153 holes, 1517 metres of rotary drilling in 23 holes, 1669 metres of hand trenching, 2047 metres of mechanical trenching, detailed geological mapping, 64 measured sections and two exploration adits (Coal Assessment Report 740). The majority of this work was focussed on the Lost-Fox area.
Refer to the Arctos (Lost-Fox) prospect (104H 021) for an overview of exploration history, regional geology and local geology of the northwest Groundhog (Mount Klappan) Coalfield.
Conoco acquired the Klappan property through acquisition of Gulf Canada in 2001. Fortune Minerals Limited acquired the property in July 2002 from Conoco and reported new resource figures based on the earlier work by Gulf Canada Properties Limited (Press Release - Fortune Minerals Ltd., July 12, 2002).
In July 2011, Fortune Minerals Limited agreed to form a joint venture with POSCO Canada and its wholly-owned subsidiary, POSCO Klappan Coal Ltd., to advance the Mount Klappan project to production. POSCAN's parent company, POSCO, is based in South Korea and is one of the world's largest steel producers. POSCO acquired 20 per cent interest in Mount Klappan.
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), 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). Gulf Canada referred to the coal-bearing unit as the Klappan Series during their exploration programs in the 1980s (Coal Exploration Report 740). 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.
The Mount Klappan (Summit) deposit comprises multiple coal seams underlying the Summit airstrip area. Exploration at the Summit prospect between 1981 and 1988 included two diamond-drill holes for a total of 323 metres, 401 metres of hand trenching and 15 measured sections.
Seams G, F and D were identified at the Summit prospect. Seam widths vary from 1.3 to 3.9 metres and have an aggregate thickness of 7.9 metres (Coal Assessment Report 110). Coal quality is anticipated to be similar to the Mount Klappan (Hobbit-Broatch) and Mount Klappan (Lost-Fox) (104H 021) deposit areas which gave the following range of values (Coal Assessment Report 109):
---------------------------------------------- Low High Average Fixed carbon 41.40 88.40 68.90 Ash content 4.90 52.30 22.20 Volatile matter 5.00 16.40 9.00 Sulphur content 0.29 1.11 0.57 Calorific value 3,114.00 7,782.00 6,086.00 ---------------------------------------------- |
The above values are based on raw coal and are stated in per cent except for calorific values which are in calories per gram. Rank as estimated by fixed carbon to volatile matter ratio indicates a range between low volatile bituminous and anthracite; however, this method of coal rank determination may be misleading as samples were collected from near-surface trenches.
In 1984, Gulf Canada reported inferred resources at the Summit prospect of 41.4 million tonnes and a further speculative resource of 1,860,100,000 tonnes (Coal Assessment Report 709).
Exploration at the Nass prospect between 1981 and 1988 included 141 metres of hand trenching and three measured sections. Exploration at the Skeena prospect between 1981 and 1988 included six metres of hand trenching in two trenches.
Fortune Minerals reported a calculation of 2.4 million tonnes of anthracite inventory at the Summit prospect in 2007, based on data collected during the Gulf Canada exploration projects of the 1980s (Technical Report on the Lost-Fox Area Thermal Coal Supply Pre-Feasibility Study, for Fortune Minerals, Marston Canada, March 2007).
In August 2012, Fortune Minerals and Posco Canada renamed the Mount Klappan project as the Arctos Anthracite Project. Fortune Minerals reports a collective 231 million tonnes of measured and indicated resources and 359 million tonnes inferred resources across the Arctos Anthracite Project (Fortune Minerals Ltd 2011 Annual Review; See 104H 021 Arctos (Lost-Fox)). Located in four areas (Lost Fox, Hobbit-Broatch, Summit and Nass), there are 33 coal seams up to 11 metres in thickness to a depth of 380 metres (Fortune Minerals Ltd. News Release June 25, 2012).
Fortune Minerals voluntarily pulled out of the exploration area to allow for continued talks between the Tahltan First Nation and the B.C. government concerning land development around the headwaters of the Nass, Skeena and Stikine rivers (Fortune Minerals Ltd. News Release September 24, 2013).
