The Coper Keg project covers 3,272 ha, located on the northern end of the prolific Guichon Creek batholith, the host to Teck Resources, Highland Valley mining complex. Four major porphyry Cu (±Mo) systems, hosted in various intrusive facies of the Guichon batholith, occur in the HVC district. The porphyry copper systems in the HVC occur along major regional scale faults that exerted significant control on the porphyry copper system.
Historical exploration spans from the late 1800’s to 2012. The early stage exploration is reported to consist of mining high grade copper veins see below:
“Spectacular gossan” several km's long, located about 9 kilometres from Ashcroft, BC Minister of Mines Annual Report for 1898: “...a large body of ore, carrying gold and silver, but principally copper. An adit, 24 metres long, was run in on the claims.”
Rock samples: 0.655% Cu with 1.0 oz Ag; 0.61% Cu; 0.762%Cu with 0.49 oz Ag; 0.35% Cu with 0.26 oz Ag; 2.4 oz Ag with 0.02% Cu.
BC ARIS 03246 (http://minfile.gov.bc.ca/Summary.aspx?minfilno=092INW031)
More recent exploration was limited and superficial in nature (lack of detailed data collection) consisting of soil and rock sampling, limited geophysical surveys and cursory mapping. Comments are based on review of the assessment reports (1970-2012) filed on the property. A field inspection and verification of the reported information from the property has not been completed.
The property exhibits the geochemical/alteration/lithologic features typical of the argillic altered potion of a porphyry copper system at/along the potassic/propylitic contact. The property is characterized by a large, pyrite bearing, argillic zone exposed along the surface trace of the Barnes Creek fault, a major NNW trending that crosses the Guichon Creek Batholith. The high-grade copper veins noted above, reflect supergene enrichment of distal base metal veins typically associated with a porphyry copper system.
Mapping has described pale grey-green (possibly phyllic alteration) outcrops of Guichon intrusive and late-stage Quartz Feldspar and Quartz Feldspar Hornblende dikes indicating multi-phase intrusive activity. The hydrothermal alteration is post Guichon intrusive and pre-dates the late-stage intrusive dikes.
The erratic and wide range of copper values (0.025 to 0.76%), in the gossanous (after pyrite), argillic altered zone exhibits characteristics of what is referred to as in porphyry copper geology as a Leach Cap. Weak geochemical (Cu +/- Mo) and chargeability anomalies and multi-phase intrusive activity are consistent with this interpretation.
The project is underlain by an intrusive phase of the Guichon Creek batholith intruded the surrounding Nicola Group rocks.
While the exploration has not been systematic, the data does provide helpful insight into geological development and alteration process that were active within the property.
Petrographic work and K/Al: Na/Al ratios indicate an alteration package ranging from argillic-phyllic- potassic (all alteration phases associated with porphyry copper systems) supported by alteration minerals indicative of the inner actinolite subzone of a porphyry system as well as secondary biotite (Potassic alteration) and sericite (phyllic alteration), quartz veinlets with pyrite and chalcopyrite.
A large pyritic zone exhibit spatial association with the argillic altered zone and could be representative of what is commonly referred to in porphyry copper terms as the “pyrite shell”. Chalcopyrite, bornite and malachite (secondary copper carbonate) have been observed in outcrop and supports the presence of a porphyry system..
Weak copper-silver-molybdenum in soil anomalies suggest weathering/oxidization of pyrite associated with porphyry sulphide mineralization creating a highly acidic conditions that dissolves elements such as copper and reconcentrates these elements at depth; resulting in the formation of a “Leach Cap”. Malachite is an indicator mineral of the leaching process.
Two highly altered gossans have been identified along the interpreted trace of the Barnes Creek fault, a major structure within the Guichon Creek batholith. The first area (800m long by 200m wide); the second area is 600 m south and smaller in extent. These gossans exhibit erratic copper concentrations, weak copper-silver soil anomalies and copper mineralogy typical of a Leach Cap.
IP survey completed in 1971 (limited coverage) identified weak to moderate chargeability signatures associated with the altered gossans.
Future work on the property is warranted and should consist of the following;
- Detailed mapping collecting information on lithology, alteration and mineralization at the outcrop level.
- Rock characterization program (48 elements) to map geochemical trends that can be used to vector toward the core of the porphyry system
- Property wide, deep penetrating (+600m) chargability/resistivity geophysical survey to map the distribution of the alteration and pyrite zones and provide information on the structural framework of the property.