Summary:
The known deposits within the Atlantic operation area are considered to be examples of turbidite-hosted, orogenic mesothermal gold deposits.
The Meguma Terrane of Nova Scotia hosts the Moose River Member, Tangier Member, and Taylors Head Member of the basal greywacke-dominated Goldenville Formation. Gold mineralization is generally hosted in argillite and/or greywacke sequences of the Moose River Member and is associated with regional-scale anticlines. Structural repetition due to folding and faulting may result in thickening of gold-bearing units.
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. Mineralization is associated with sulphides, including arsenopyrite, pyrite and pyrrhotite. Lesser chalcopyrite, galena, and sphalerite have been observed.
Gold grade was estimated using multiple indicator kriging (MIK) for all deposits. The basic unit of estimation is a panel with horizontal dimensions equal to the average drill hole spacing.
Dimensions
Touquoy: strike extent = 810m ; width = 50m; vertical extent = 150m.
Beaver Dam: strike extent = 810m ; width = 50m; vertical extent = 200m.
Fifteen Mile Stream: strike extent = 1400m ; width = variable 20m to 100m; vertical extent = 225m.
Cochrane Hill: strike extent = 950m ; width = 70m; vertical extent = 285m.
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.
The anticline geometry varies along its length in the property area, from an upright tightly-folded anticline in the vicinity of the Touquoy deposit to multiple tight folds, overturned to the north, in the Stillwater area.
The argillite unit is as much as 180 m thick close to the hinge in the northern limb and appears to thin with depth. It is much thinner in the southern limb, typically 25–60 m wide. In the northern limb, the Touquoy argillite is separated into upper and lower units by a distinctive marker horizon, the rip-up unit, which varies from a thin (<2 m thick) horizon of sparse sandstone rip-up clasts in a finer grained matrix to a fine or medium grained greywacke. The rip-up unit has only rarely been recognized in the southern limb.
The Moose River–Fifteen Mile Stream Anticline is tightly folded and upright to overturned with both limbs dipping north. The anticline hinge is doubly-plunging, with shallow plunges to both northeast and southwest. It has been disrupted by a number of northwest-trending faults with contrasting fold geometries occurring on opposite sides of some of those faults showing that folding and some of the faulting had similar timing.
Two major faults appear to have a significant effect on mineralization thickness at Touquoy, the curvilinear West Fault and the relatively planar Northeast Fault:
• The West Fault is interpreted to show normal movement such that the anticline to the east of the fault has dropped and argillite on the southern limb of the anticline, west of the West Fault shows relative displacement to the south;
• The Northeast Fault comprises an approximately 10 m to 20 m wide zone with intensely faulted and fragmented intervals separated by weakly sheared or quite coherent intervals. It juxtaposes a sequence of barren or very weakly goldanomalous argillite and greywacke against the Touquoy argillite and its hanging wall units.
A discrete structure (or structures) parallel to the anticline axial surface and representing a hinge fault or faults has been tentatively identified in several drill sections, and may have a role in localising gold mineralization.
A series of north- to northeast-trending and east- to northeast-trending faults have displaced both stratigraphy and gold mineralization, although it is possible that some of these faults were also active during gold mineralization.
A well-developed axial plane cleavage is recognised within argillite layers while greywacke layers exhibit weakly developed pressure solution cleavage. Flexural slip occurred during folding and disruptions in bedding orientation in the hinge position is interpreted to reflect repetition (crumpling) of the fold hinge, to produce parallel fold axes at Touquoy.
The Touquoy host rocks have been metamorphosed to lower greenschist facies such that the dominant mineral assemblage in the argillites is quartz, muscovite, chlorite ± albite, with accessory ilmenite and rutile.
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.
Gold grain size as indicated by petrographic studies varies from 1 µm to >1 mm and gold grains up to 1.5 mm in size have been observed. Sulphide minerals accompanying the gold mineralization are pyrrhotite, usually aligned along the axial plane cleavage (1–2%), arsenopyrite, often as coarse porphyroblasts (1%) and pyrite (<1%). Other sulphides are rare. At a macro scale, there is typically poor correlation between arsenic and gold content.