Summary:
The Huguenot Coal Project is located along the northeastern limb of a broad, northwest-plunging anticlinorium (the Belcourt Anticlinorium). Lower Cretaceous coal measures are located along the western and eastern margins of this structure, while Triassic and Jurassic strata occupy the central portions. The western extent of the anticlinorium is defined by a major, westerly-dipping thrust fault that emplaced Palaeozoic rocks upon the Lower Cretaceous strata. Eastward from the core of the Anticlinorium, the Cretaceous succession is continuous, the youngest strata being those of the Kaskapau Formation (Late Cretaceous). The Huguenot property is located within a narrow, northwesterly-trending band of tight to relatively open folds and associated northeasterly-verging thrust faults that have placed older units upon younger.
The Gates coal measures are repeated by two easterly-dipping and easterly-verging thrust faults, the Holtslander North and Holtslander South Thrusts. For descriptiven purposes, the three structural slices are referred to as the North, Middle, and South Blocks.
Mining sections have been defined either from discrete coal seams where all, or most, of the coal-bearing interval forms a single mining section, or as parts of a coal zone where one or more coal layers occurring in relatively close vertical proximity to one another, form separate mining sections. Thin, internal, rock bands, if present, are included in the mining sections but thicker rock bands (in this instance 0.31 m or more, as defined in GSC Paper 88-21) are omitted, even though, in practice, some would almost certainly be mined with coal in medium- to large-scale production scenarios. In the discussions presented below, the mining sections are taken to a minimum true thickness of 0.60m. Coal at Huguenot can form discrete coal seams of variable thickness, or form thin seams interbedded with coaly shale and carbonaceous shale to form coal zones which, in themselves, are mappable stratigraphic units. Some “zones” consist of only one mappable coal layer/ply where other zones may include multiple mappable coal layers.
North Block.
A total of ten coal seams and/or coal zones are present within the North Block. Seam/coal zone nomenclature used in this report follows that used by Denison across their former Belcourt property; in ascending order they are numbered 1 through 10. The main coal splits that form part of a coal zone are assigned the number of the zone plus a letter.
The letter 'A' indicates the lowermost coal split in a series; however, this is complicated in Coal Zone 6 by the presence of coal splits below Seam 6A. Consequently, this part of the zone is referred to as 6l.
All seams/coal zones with the exception of Seams 7 and 10 provide potentially mineable coal intervals. The main coal seams are Seams 1, 5, 6B, and 8; these are the thickest and most laterally continuous of the coal seams. Typically, the minor seams (i.e., 2A, 3B/3B Lower (3Bl), 3D, 4, 6l, 6A, 6C Lower (6Cl), 6D, and 9) meet seam thickness or coal to rock (C/R) ratio minimums only over portions of the blocks. Seams not considered to be potentially mineable, can still be traced geologically throughout the remainder of the block. Other coal seams/splits such as 3A, 8B and some splits above Seam 9 might locally exceed 0.60m in thickness but are not currently deemed to be persistent enough to present mineable targets.
The North Block sits structurally above the Holtslander North Thrust Fault. Gates Formation coal measures occupy the western limb of a broad synclinal structure called the Holtslander Synclinorium. In the west, the strata are near homoclinal with moderate (approximately 45°) north-northeasterly dips. To the east, the strike swings easterly such that dips are to the north. Dips are also steeper in the east, reaching approximately 50°. Dip values decrease at depth to between 30° and 35°, reflecting proximity to the axial zone of the syncline.
Middle Block.
A total of ten coal seams and/or coal zones are present within the Middle Block. All seams/coal zones with the exception of Seam 7 provide potentially mineable coal intervals. The main coal seams are Seams 1, 5, 6L, and 8; these are the thickest and most laterally continuous of the coal seams. Minor seams 2A, 3B, 4u, 6B and 9 meet seam thickness and C/R ratio minimums across the Middle Block, whereas seams 2D, 2EF, 2HI, 6D and 10 meet mining section criteria locally. Where these latter seams do not meet seam thickness or C/R ratio minimums, they can still be traced geologically. Coal seams in the Middle Block are progressively terminated towards the south by the Holtslander South Thrust Fault such that the lowermost seams only extend as far south as the central portion of the block. Only seams stratigraphically higher than Seam 6B are present at the southern end of the block.
The Middle Block sits structurally below the Holtslander North Thrust and above the Holtslander South Thrust. The coal measures occupy the western limb of a broad synclinal structure called the Holtslander Synclinorium. At the northern end of the Middle Block the strata dip northeasterly, between 45° and 55°. Dip values increase to between 50° and 85° towards the centre of the block, decreasing to between 30° and 65° at the southern end. A northerly-trending, open, upright, anticline-syncline pair is mapped along the eastern edge of the thrust slice. These structures are interpreted to affect the Holtslander South Thrust as well as the overlying coal measures.
South Block.
Of the 10 coal seams and/or coal zones present within the South Block all seams/coal zones except 3, 7 and 10 provide potentially mineable coal intervals. The thickest and most laterally continuous of the coal seams are Seams 1,2Z, 4, 5, and 6L; Seams 6B, 6D, 8 and 9 are present in the southern half of the block. The distribution of the Gates coal measures within the South Block is largely determined by the presence and attitude of the Holtslander South Thrust Fault. Surface traces of the stratigraphically higher coal seams (above 6L) are progressively terminated towards the north by this thrust fault; this fault also forms the northern limit of the coal seam traces and of the South Block as defined herein.
The South Block forms the lowest structural unit. Most of the coal seams are contained within steep, easterly-dipping beds (60° and 75°) which steepen towards the south (70° and 85°); they are often overturned along their up-dip sections (to provide very steep, southwesterly dips). These strata form the eastern limb of an asymmetric anticline, the fold axis of which almost defines the western limit of the coal measures. This anticline may represent the eastern side of a large northerly-trending, box fold.