Mackenzie Project, British Columbia
The Mackenzie property is located in southwestern British Columbia, approximately 100 kilometres west of Lillooet the nearest population centre, railhead, source of high tension power and major roads (Figure 1). It consists of 38 contiguous claims, aggregating 156.13 km2. Carube Copper is 100% owner of the property subject to a net smelter royalty. Forest service access roads cross the northern and southern claim boundaries and link the property with the town of Gold Bridge, which is located about 40 kilometres to the east. The property is located immediately south of Amarc Resources 2014 IKE discovery.
Copper mineralization was located on the property by the vendor, a retired doctor/prospector in 2003. There is no assessment record or indication on the surface that the mineralization has ever been explored by a mineral exploration company.
Work until the summer of 2012 was focused on the original discovery showing where copper mineralization is hosted by a brittle structure which is exposed in a continuous zone for a distance of greater than 1.0 kilometre on a near-vertical rock face at the head of a glacial cirque (Figure 2).
The copper-gold-molybdenum-rhenium geochemical fingerprint of the fracture controlled mineralization and the identification of weakly mineralized, fine-grained granodiorite dykes that are intimately associated with mineralization and with patchy and vein-related potassic (potassium feldspar) alteration, strongly suggested a porphyry style origin for the mineralization.
As a result the size of its Mackenzie property was increased eight-fold in early 2012 to expand the area available for exploration for the source of the exposed high grade fracture controlled surface mineralization.
The 2012 exploration program at Mackenzie focused on drill testing the high-grade mineralized discovery structure known as the Tillworth Trend (Figure 4), as well as surface mapping and sampling of the remainder of the expanded property.
Drilling results confirmed the continuity of the Tillworth structure to depth, but the results also confirmed the narrow nature of the mineralized fracture zone, and the apparent lack of subsidiary structures. Thus, although, as a result of the mapping carried out concurrently with the drilling, the strike length of the Tillworth Trend was extended to 13 kilometres, the potential of this zone as a high tonnage potentially economic target seems limited.
The summer 2012 field mapping program was highly successful in identifying two new mineralized areas on the property. These are known as the Breccia Trend and the Bornite Trend. (Figure 4).
Together with the original discovery, the Tillworth Trend, the Breccia Trend and the Bornite Trend define a zoned mineralized environment which extends ~12 kilometres outwards from the contact of the Miocene aged Bridge River Pluton.
The Breccia Trend (Figure 4), which is furthest out consists of a deeply weathered, silicified, gossanous breccia and several smaller gossans and has an open-ended 5 kilometre strike length. Streams draining this area show elevated values of copper to 108 ppm, or 2 to 3 times background and elevated levels of arsenic (to 29.5 ppm As), antimony (to 25 ppm Sb) and zinc (to 108 ppm Zn). The outcrop is deeply weathered and highly leached and very little fresh rock is exposed, but two silicified grab samples (M487778 and M487779) returned values of 0.174% Cu and 0.211% Cu respectively, with elevated levels of arsenic (693 and 419 ppm As), indium (0.108 and 0.16 ppm In), antimony (346 and 331 ppm Sb), and zinc (284 and 239 ppm Zn), respectively, typical of the geochemistry of high level epithermal systems which are found peripheral to porphyry systems.
The Tillworth Trend, which hosts the original Mackenzie discovery showing as well as quartz-chalcopyrite ± bornite ± molybdenite veins and stringers up to 30 cm wide along strike to the northwest and southeast. At the main Mackenzie showing Cu-Au-Ag-Mo mineralization occurs in a single high-grade, mineralized fracture system ranging in thickness from 0.3 metres to 9 metres. The mineralized structure is spatially associated with younger, fine-grained granodioritic and dioritic rocks of possible Miocene age similar to the age of the Bridge River Pluton. Of the 38 grab samples collected along the Tillworth Trend in 2012 (Table 2), the 26 samples with copper values ranging from 0.1% to a maximum of 17% Cu have gold and silver values from 0.001 to 1.46 g/t Au and 0.120 to 78 g/t Ag, respectively.
Mineralization in the westernmost Bornite Trend (Figure 4), which has an open-ended strike length of 7.5 kilometres, consists of scattered quartz-bornite-chalcocite- magnetite ± chalcopyrite ± tetrahedrite veins and stringers up to 20 centimetres wide. These occur along the edge of the Miocene-age Bridge River pluton and within the host Coast Plutonic Complex and therefore are interpreted to be of Miocene age. Fourteen of the 27 grab samples collected along the Bornite Trend during the initial reconnaissance of this area in 2012 have copper values in excess of 0.25% copper with values ranging up to a maximum of 4.34% Cu with gold and silver values ranging from 0.001 to 0.445 g/t Au, and from 3.34 to 4,170 g/t Ag, respectively.
The limited work carried out on the property to date has delineated a mineralized environment associated with the Miocene Age Bridge River Pluton. To date, several mineralized areas have been discovered extending some 12 kilometres out from the contact of this intrusion.
The Bornite Trend, discovered in 2012 on the western part of the property represents a large extremely attractive exploration target. The Bornite Trend consists of a 7.5 kilometre long trend of scattered quartz-bornite-chalcocite-magnetite ± chalcopyrite ± tetrahedrite veins and stringers, both within the Miocene-age Bridge River pluton and within the host Coast Plutonic Complex. The mineralization was only discovered toward the end of the 2012 program, and the nature of the mineralization dictates it does not stand out in the field. Additional mapping and sampling is warranted to fully delineate the extent of this zone.
The presence of magnetite in the quartz-bornite-chalcocite veins, made this a target that should be readily identifiable by airborne magnetics. In 2015, a 634 line-kilometer airborne magnetics and radiometrics survey was flown over the western half of the property, covering the Bornite Trend in the process. Results were encouraging showing elevated magnetics where expected over the zone of known quartz-magnetite-bornite veins, but it also delineated a large magnetic body below surface just southeast along strike. This zone was further modelled and showed a large, highly magnetic body below surface with several cupola or “finger like” bodies emanating from it towards surface. This was found to be very encouraging given the association of magnetite with the mineralization in the adjacent rock packages along with the typical cupola formation within porphyry systems. Follow-up is now required in this area.
The current proposed work program includes a follow-up ground IP survey covering the entire Bornite trend including the high magnetics cupola zone, as well as extending airborne magnetic and resistivity coverage over the Breccia Trend on the eastern part of the property. This will be followed up by ground work in the form of mapping and sampling. Targets developed by the geophysics surveys and follow-up ground work will be drill tested.