The immediate area of Red Cap prospects are underlain by volcanic flows, pyroclastic rock units, and sedimentary rocks. Volcanic rock units of the Jurassic Laberge group consist of rhyolitic (?) to basaltic flows, volcanic breccia, agglomerate, tuffs, and minor volcanic sandstone. Later petrographic analysis of rock mapped in the field as rhyolite indicated that they were in fact a bleached and silicified intermediate rock. The volcanic units are underlain by sedimentary rock units of the Upper Stuhini Group consisting of thick-bedded, dark greywacke, conglomerate, mudstone, siltstone, and shale with minor volcanic flows, tuffs, breccia, limy shale, and limestone. Laberge Group sediments are reported along the southern margin of the prospect area and are composed of conglomerate, sandstone, shale, and greywacke. Hornblende-biotite granodiorite stocks and associated feldspar porphyry dikes intrude the strata and are assigned to the Late Cretaceous Windy Table Complex. In the prospect area, these intrusive rocks consist of light grey, medium crystalline granodiorite and a darker grey diorite or quartz diorite.
There are three main structural components in the Red Cap prospect area. The most pronounced of these is an east-northeast trending fault, located on the the north. The second major structure strikes in a northeast direction and runs through the core of the porphyry intrusion. The third structure cuts through the northeast. This system of east-west and northeast-southwest faults and fractures form the basic fabric of the area and their presence is thought to have controlled subsequent development of stockworks within the porphyry system and appear to have influenced the distribution of the associated mineralization (Assessment Report 25970).
The RV, PF, Bergie, X-Berg (Berg), Goat and LJ showings are all part of the East Cirque zone and consist of quartz-massive sulphide veins up to 2.5 metres wide (Assessment Report 18803, Figure 4). The veins occur within gossanous, limonitic quartz, sericite, clay and chlorite altered felsic and intermediate volcanics and agglomerates. Sulphides include arsenopyrite, sphalerite, pyrrhotite, galena, chalcopyrite and pyrite. The veins strike in a northeast-southwest and an east-west direction.
The best precious metal showing from 1988 was from the RV showing which yielded 128.6 grams per tonne silver, 34.99 grams per tonne gold and 9.33 per cent zinc over 90 centimetres of vein width. In 1998, a twelve-hole diamond drilling program was designed to test the LJ, RV, Bergie, and X-Berg showings (Assessment Report 25970). Gold and silver mineralization was intersected in holes LJ-98-5B and RV-98-10. In hole LJ-98-5B, 3 metres grading 3.7 grams per tonne gold and 26.0 grams per tonne silver were intersected. In RV-98-10, there were two intersections of note: 7.15 metres grading 12.05 grams per tonne gold and 49.50 grams per tonne silver; and a second adjacent 4.73 metre interval grading 2.50 grams per tonne gold and 18.37 grams per tonne silver.
The Slope (104K 010), Ridge (104K 085) and East Cirque zones are considered by Wilkins and MacKinnon (Assessment Report 18803) to be part of one large porphyry system with the Slope representing the stockwork and sheeted vein-hosted copper and molybdenum mineralized core. The Ridge and East Cirque zones to the northeast of the Slope and possibly “Moly and Copper creeks” (Silica Cap) to the southwest may represent structurally controlled conduits for sulphide bearing hydrothermal solutions. These are characterized by massive sulphide veins up to 2 metres in size with associated precious metals. Gold and silver mineralization occurs throughout the system with higher grades concentrated away from the copper-molybdenum core.
See Slope (104K010) for a discussion of the Red Cap property history which includes the East Cirque.
