Summary:
The majority of EVR Operations’ coal Resources and Reserves are contained within the Elk River Coalfield and the Crowsnest Coalfield in the East Kootenay area of British Columbia.
The coal measures are situated within the Upper Jurassic to Lower Cretaceous Kootenay Group sediments.
From earliest to latest, the Kootenay Group includes:
• Morrissey Formation: sandstones; subdivided into the Weary Ridge and Moose Mountain Members; 20–80 m in thickness;
• Mist Mountain Formation: interbedded sandstone, siltstone, mudstone, shale and thin to thick seams of bituminous to semi-anthracite coal; 450–550 m in thickness;
• Elk Formation: interbedded sandstone, siltstone, mudstone, shale and locally thick beds of chert-pebble conglomerate and thin seams of high volatile bituminous coal; 350–450 m in thickness.
The Mist Mountain Formation contains approximately 25 coal seams of potential economic interest, consisting of medium to high volatile bituminous coal.
Within the coal measures, there are three structurally-separated coalfields, the Elk Valley, Crowsnest, and Flathead coalfields. The Elk Valley coalfield is located within the Alexander Creek and Greenhills synclines, which are separated by a normal fault. The western edge of the Mist Mountain Formation, and therefore the distribution of the Elk Valley coalfield, is controlled by the Bourgeau Fault. To the east of this fault, the Greenhills syncline plunges to the north, and its eastern limb is truncated by the north-trending normal Erickson fault. East of the Erickson fault is the Alexander Creek syncline, which is in turn cut by the Ewin Pass thrust fault (Ryan, 2001).
The coal seams in both synclines are typically fragmented and sheared. Thicker seams are generally lower in the section, tend to host major thrusts, and therefore are frequently extensively sheared (Ryan, 2001).
Greenhills Syncline
The east limb of the asymmetric Greenhills syncline dips westerly at 15–25°, except in areas near the Erickson Fault, where 45–55° dips are common. The west limb exhibits much steeper dips, commonly in the 32–45° range. The Greenhills Syncline plunges northward (340–350°), at less than 5°, and then thins out and seems to end to the north in the area of the Osborne Creek Depression (Lake Mountain) (Mills et al., 2020).
Erickson Fault
The Erickson Fault, which locally runs along the base of the Greenhills Range, west of the Fording River, is one of the major regional faults. From south to north, this westerly dipping (40–70°) normal fault brings Mist Mountain strata progressively into contact with Rundle, Rock Mountain, Spray River, Fernie and Morrissey strata. The downthrown block is to the west.
Near the south end of Lake Mountain, the Erickson Faults begins to “splay” into two zones. The main fault runs along the eastern margin of Lake Mountain, and the subsidiary fault runs to the west and appears to thin out and end northward. The steep northward dip exhibited in the Lake Mountain strata could be due to influence from these flanking “splays” of the fault. The flat-lying region to the north of Lake Mountain (Osborne Creek Depression area) is completely void of out-crop, and the Erickson Fault has not been traced either through or to the north of this area (Mills et al., 2020).
Mineralization
The Mist Mountain Formation depth of burial ranges from surface exposures to greater than 1,500 m. The coal measures on the GHO property contain bituminous grade coal seams with varying volatile matter contents. The coal quality varies with depth of burial and location along the strike of the deposit. Seams may range in thickness from 1–16 m.
Elkview mine
The major structure in the Project area is a southwest plunging syncline, the Sparwood (Michel) Syncline. Multiple thrust faults and normal faults occur throughout the Project area, mostly striking in a northwest to southeast orientation. The thrust faults generally dip west to southwest at inclinations of 20–50°. This has resulted in coal seam repeats and structural deformation and complexity along the thrust fault boundaries, by overlapping and drag folding.
The tectonic thickening of the basal 10-seam is an important factor in mine planning.
The Mist Mountain Formation depth of burial ranges from surface exposures to >750 m. The coal measures on the EVO contain bituminous grade coal seams with varying volatile matter contents. The coal quality varies with depth of burial and location along the strike of the deposit. Seams may range in thickness from <1 m to >15 m.
Seams range in rank from high to low volatile bituminous and are numbered from 10 at the base, upwards to 1, with additional seams A through D at the top of the 600 m thick stratigraphic column. All mineable coal seams in Baldy, Adit and Natal Ridges are within the Mist Mountain Formation. A portion of the Fernie Formation occurs at the top of Adit Ridge.
These are the areas in which over thrusted repeats of 10-seam may be found due to the thrust fault thickening, and as such, required an increased drilling density to maintain the geological assurance. Zones of complex geology pass through Baldy Ridge, Adit Ridge and Natal Ridge and are adjacent to the fault lines. About half of the deposit at EVO is classified as complex, with the remaining half classified as moderate.
Line Creek operations
At the Line Creek operations, sixteen coal zones (E, D, C, B, A, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10B and 10A, from top to bottom) with a net aggregate thickness of 67.4 metres in 91.7 metres of gross aggregate coal section, occur in the Jurassic-Cretaceous Mist Mountain Formation (440 to 500 metres thick) (Kootenay Group) interbedded with sandstone, shale and siltstone.
The main seams are the 10B seam (average thickness 4.5 metres - thins north); 9 seam (two seams, average thickness 5.4 metres in a 6.4 metre zone - thins north and west); 8 seam (thickest seam - averages 11.6 metres in a 12.8 metre thick coal zone); 7 seam (averages 5.2 to 6.3 metres); 6 seam (two seams average 5.0 metres and 12.0 metres respectively - thickens southwest); 4 seam, which in the south is two seams, 5.0 and 12.5 metres respectively, and in the north is a single thick seam but with a shale split in the northeast, 11.6 and 12.0 metres respectively; 3 lower seam (single or multiple thin seams - 3.3 to 3.8 metres, disappears to the northwest); 3-Upper seam (4.0 to 6.0 metres average thickness, lower 50 to 75 per cent is a single coal seam with thin variable shale splits, upper portion consists of multiple thin coal seams with shale partings); and A seam (2 seams in the south, single thick seam in the north, average thickness is 3.0 to 4.0 metres). The remaining seams are commonly multiple, thinner (less than 3.0 metres) and tend to contain shale partings.
Ash contents range from 5 to 16 per cent (generally 7 to 8 per cent), volatile matter from 19.5 to 30.0 per cent and sulphur from 0.3 to 0.9 per cent (air dried basis). The coal is medium volatile bituminous in rank.
Greenhills mine
At Greenhills, up to 24 coal seams occur in the Jurassic-Cretaceous Mist Mountain Formation (Kootenay Group) interbedded with sandstone, siltstone and shale. The major seams, which are continuous throughout the area, are named 1, 7, 10, 16 and 20. Seams 1, 7 and 10 (68 per cent of in place geological reserves) are medium volatile bituminous coal, while seam 16 and other stratigraphically higher seams are high volatile A bituminous in rank. Other major seams are lenticular and less extensive (several kilometres extent) and occur generally in the upper half of the Mist Mountain Formation. Thicknesses of the major seams are as follows from oldest to youngest; seam 1 (10 to 16 metres), 7 (7 to 11 metres), 10 and 10L (5 to 11 metres), 16 and 16L (5 to 11 metres, and seam 20 (2 to 7 metres).