Summary:
Atlantic Operations include the Touquoy open pit and three nearby projects: Beaver Dam, 15 Mile (formerly Fifteen Mile Stream), and Cochrane Hill.
Touquoy deposite
A number of argillite units, separated by greywackes, occur within the Touquoy property. Mineralization is hosted within the Touquoy argillite unit of the Moose River Formation of the Goldenville Group. The argillite is folded around the Moose River–Fifteen Mile Stream Anticline, a regional structure that can be traced for at least 47 km from a position approximately 6 km south west of the Touquoy deposit, to approximately 4 km northeast of Fifteen Mile Stream.
Gold mineralization is best developed in the northern limb of the anticline where it broadly conforms to bedding over a strike length of approximately 600 m. Mineralization is less persistent in the anticlinal hinge but is well developed in the southern limb over a strike length of approximately 250 m where a bedding control is less apparent but where mineralization is associated with shearing near the contact between the Touquoy argillite and hanging wall Touquoy greywacke.
Gold occurs as native gold, and has been observed in a number of settings, including along shear cleavage, hair line fractures; in pressure shadows; as inclusions; on the margins of sulphide grains; in thin bedding-parallel quartz veins and stringers where it is often associated with pyrite or pyrrhotite and sometimes with base metal sulphides, particularly galena and chalcopyrite; and on the margins of tightly-folded quartz veins, often at, or close to, fold hinges.
Dimensions Touquoy: strike extent = 810m ; width = 50m; vertical extent = 150m.
15 Mile
The 15 Mile (previously Fifteen Mile Stream) Project consists of Egerton-Maclean, Plenty, Hudson and 149 Deposits.
At Fifteen Mile Stream, the highest gold grades are typically associated with beddingparallel tabular quartz veins. However, the host rock material between quartz veins also carries significant gold grades. It is the quartz vein hosted gold mineralization augmented by disseminated style mineralization that forms the basis of a geological model associated with the ongoing exploration and development of the Fifteen Mile Stream gold deposit.
Mineralization at Fifteen Mile Stream is focused in the hinge of a regional anticline and generally conforms to a saddle-reef style model where veins and related alteration occur in bedding-parallel structures resulting from folding. Fold related strain is focused within the softer meta-mudstone units thus mineralization is generally controlled by stratigraphy, with bedding-parallel quartz veins and related alteration mainly confined to meta-mudstone intervals. True saddle-reef quartz veins do not occur within any of the mineralized zones. However a thick bedding-parallel quartz vein referred to as the ‘Big Bull Vein’ in the centre of the district is interpreted as a saddle-reef vein.
Gold mineralization within the FMS is largely hosted by bedding-parallel quartz veins that are buckled and folded with the enclosing sedimentary beds. Two main vein styles include massive milky white veins and laminated veins, the latter typically smoky in colour and characterized by vein-parallel inclusions. Weak wall rock alteration spatially associated with the veins includes carbonitization and, locally, sericitization. Associated sulphide mineralization includes arsenopyrite, pyrite and pyrrhotite with the pyrrhotite frequently hosting minor chalcopyrite. Arsenopyrite modally comprises trace amounts of around three percent and occurs as equant, subhedral grains 1-5mm in diameter.
Mineralization in the Hudson Zone is confined to the Egerton-McLean stratigraphy and is similar in character to that noted in the Egerton-McLean Zone i.e. coarse gold in veins and finer free gold in altered wall rock. The Fifteen Mile Stream Anticline in the Hudson Zone is overturned as in the Egerton-McLean Zone. However the fold in the Hudson area is tight with a narrow, angular hinge and lacks the complex decametre folds that characterized the Egerton-McLean Zone. The lack of folding in the hinge area results in a smaller mineralized zone due to the lack of repetition.
The Plenty Zone occurs on the south limb of the Fifteen Mile Stream Anticline approximately 400 m southwest of the Egerton-McLean area. The mineralized zone is controlled by stratigraphy and bedding-parallel quartz veins that are steeply dipping. Gold was reported to occur in quartz veins and argillite (meta-mudstone) (Morris, 1986).
Dimensions 15 Mile: strike extent = 1400m ; width = variable 20m to 100m; vertical extent = 225m.
Beaver Dam
Geology
The Beaver Dam deposit is hosted in the southern limb of a north-dipping overturned anticlinal fold. The Moose River Formation is relatively thick in the vicinity of the Beaver Dam deposit.
Mineralization
Gold mineralization at Beaver Dam has been recognised over a strike length of approximately 1.4 km, extending from the Main Zone northwest to the Mill Shaft Zone. Historical drilling has shown that mineralization weakens between the Main Zone and Mill Shaft Zone. The eastern end of the main zone is controlled by the Mud Lake Fault and possible offsets to the mineralization have been identified between the Mud Lake and Cameron Flowage faults and in the Northeast Zone, immediately east of the Cameron Flowage Fault.
The mineralised zone can reach as much as 100 m in width with better gold grade (e.g., >0.5 g/t) material typically confined to a 5–40 m width or widths within that zone. Mineralization has been identified in historical drill holes at vertical depths of >600 m below surface, and remains open below that depth.
Gold mineralization is hosted within quartz veins and within the argillite and greywacke host rocks. Mineralized quartz veins are typically 0.5–20 cm in thickness, are commonly bedding parallel, but can also include cross-cutting veins. Sulphide assemblages include pyrrhotite, pyrite and/or arsenopyrite with lesser chalcopyrite, galena or sphalerite. Gold commonly occurs within quartz veins as coarse (>1 mm) grains and clusters of finer, but still visible (<1 mm), grains. Coarse gold grains are more likely to be found at vein-wall rock contacts and are often spatially associated with sulphides.
Dimensions Beaver Dam: strike extent = 800m ; width = 50m; vertical extent = 200m.
Cochrane Hill
The Cochrane Hill property encompasses a section of the northeast-trending Cochrane Hill anticline which can be traced for at least 28 km from a position approximately 14 km west of the Cochrane Hill deposit, to approximately 12 km east of the Cochrane Hill deposit. The Cochrane Hill anticline is a tight to isoclinal fold in the vicinity of the Cochrane Hill deposit, overturned with both limbs dipping to the north at between 55° and 80°.
Mineralization
Mineralization is in the form of a tabular zone of parallel, planar quartz veins in a wellbedded argillite and greywacke protolith, dipping steeply to the north at approximately 70°, parallel to bedding in the southern limb of the Cochrane Hill anticline.
Gold mineralization occurs over true widths of up to 60–70 m, within which better grade material (e.g., >0.8 g/t Au) is persistent over true widths varying from 5–30 m. The base of the gold mineralization is relatively sharp in terms of grade, but the hanging wall contact is less defined, with an erratic distribution of weakly anomalous grades and occasional >1 g/t Au grades. The mineralization has been defined over a strike length of 1,500 m and down to a vertical depth of 300 m.
Gold mineralization occurs within quartz veins and within biotite schist (after argillite) and metagreywacke host rock. Mineralization is associated with sulphides, including arsenopyrite, pyrite and pyrrhotite and lesser galena and sphalerite.
Dimensions Cochrane Hill: strike extent = 950m ; width = 70m; vertical extent = 285m.