The Punch Bowl showing occurs in the Punch claims, which lie at the boundary between the eastern and the western Main Ranges of the Continental Ranges at Athabasca Pass, approximately 60 kilometres south-southwest of Jasper. This boundary is coincident with the continental divide. The boundary at this latitude is marked by the southwest dipping Chatter Creek thrust fault. Southwest of the Punch claims, the hanging wall of the Chatter Creek thrust is composed of grits, pelites, psammites and carbonates of the Hadrynian Miette Group and overlying Lower Cambrian clastics of the Gog Group. The region is dominated by broad open folds comprising the Baker Glacier syncline and Porcupine Creek anticlinorium. Northwest of the claims, the Chatter Creek thrust sheet contains the Fraser River antiform. Within the Chatter Creek thrust sheet, metamorphic grade increases westward from greenschist to kyanite-staurolite bearing assemblages of amphibolite grade.
The footwall of the Chatter Creek thrust sheet to the north and east is composed of the Lower Cambrian Gog Group, overlain by a series of thickly bedded, dominantly carbonate rocks of Middle Cambrian age striking 325 degrees and dipping 20 degrees. Tight to isoclinal, overturned mesoscopic folds occurring within imbricate quartzite slices, within this thrust sheet, have fold axes that trend 140 to 150 degrees and plunge gently southeast.
Within the claim area, the Gog Group strata are subdivided into the lowermost McNaughton, the Mural and uppermost Mahto formations, in the immediate footwall of the Chatter Creek Thrust. Gold mineralized quartz veins are contained solely within the McNaughton Formation. The predominant lithology is a medium to coarse grained, moderate to poorly sorted, pale weathering, gray feldspathic quartzite. Other lesser lithologies include pelite and conglomerate.
Paleo-environmental interpretations of the McNaughton Formation include a tidally dominated association of a shallow marine shelf environment in the Eastern Main Ranges to tidal complex transitions in more westerly outcrops.
Gold-quartz mineralization is contained in a series of discrete vein structures confined to quartzites and lesser pelites of the McNaughton Formation. Over 20 veins have produced anomalous gold values; although distribution of gold within individual veins is highly erratic. Visible gold has been observed. Thus far, only bedding parallel veins contain high grade gold mineralization. These veins vary from a few centimetres thick by 1 metre long, up to 70 to 100 centimetres wide by 50 metres long. Observations show all bedding parallel veins intrude pelite and/or quartzite with breccia textures common within veins. Vein size and distribution is fundamentally controlled by the geometry and distribution of the original pelitic layers, particularly where pelitic horizons contain greater than 30 per cent detrital quartz.
Quartz is the dominant vein filling phase, comprising over 95 per cent of the total vein volume. Variable and unevenly distributed pyrite, native gold, galena, sphalerite, carbonate and white mica, and potassium feldspar comprise the remaining modal fraction. The distribution of hydrothermal vein constituents is markedly higher in zones of intense pelite brecciation. The majority of quartz was deposited as open space filling during multiple phases of vein opening. Two broad generations of vein filling have been recognized in the building of bedding parallel veins. The second stage of vein filling represents a late incursion of hydrothermal fluids during which most of the gold was deposited. Wall rock alteration is noticeably absent adjacent to most bedding parallel veins but wall rock sulphidization likely accompanied gold stage vein filling.
With respect to regional deformation, gold mineralization appears to be late stage; hence, structures and veining associated with incipient phase three deformation may prove significant. Gold emplacement and discordant veining were confined to the onset of late compressional deformation leading to the development of the Chatter Creek thrust.
A sample taken from approximately the 2088 metre level of McGillivray Ridge was analyzed for a 32 element suite. Partial results of these analyses are: 26.29 grams per tonne gold and 0.40 gram per tonne silver (Assessment Report 19354).
