The Red Cap region is dominated by northwest trending belts of the Upper Triassic Stuhini Group and the Lower to Middle Jurassic Laberge Group. The upper contact of the Stuhini rocks with the Laberge Group is exposed on the southeast flank of Mount Lester Jones but is thought to be disconformable. Both groups have been subdivided into several regionally mappable units in the claim area. Stuhini rocks by mappable unit as indicated on the BC government MapPlace website consist of: argillite, greywacke, wacke, and conglomerate turbidites; basaltic volcanic rocks; conglomerate and coarse clastic sedimentary rocks; limestone, marble and calcareous sedimentary rocks; undivided sedimentary rocks; undivided volcanic rocks; and volcaniclastic rocks. The three designated Laberge units form part of the Takwahoni Formation and consist of andesitic volcanic rocks; argillite, greywacke, wacke and conglomerate turbidites and; conglomerate and coarse clastic sedimentary rocks. Laberge and Stuhini rocks are overlain by Tertiary continental arc volcanic rocks of the Sloko Group. Sloko rock types include coarse volcaniclastic and pyroclastic volcanic rocks; conglomerate and coarse clastic sedimentary rocks; and rhyolite and felsic volcanic rocks.
Plutons and stocks of the Paleocene to Eocene Sloko-Hyder Plutonic Suite are spatially associated with and probably comagmatic with Sloko Group volcanics. The suite consists of east-west elongated, high-level, multiphase plutons and stocks. In outcrop, these intrusions weather white, light grey, tan, pink or orange. They are compositionally and texturally variable, ranging from fine to medium grained quartz-feldspar porphyritic monzonite and diorite to granite with as much as 15 per cent biotite, magnetite, and/or hornblende. The polyphase porphyry intrusions in the Red Cap Creek area and to the southeast were thought to be part of the Sloko-Hyder Suite until recent age dating revealed them to be Late Cretaceous resulting in their reassignment to the Windy Table Complex.
The immediate area of Red Cap prospects are underlain by volcanic flows, pyroclastic rock units, and sedimentary rocks. Volcanic rock units of the 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 or the 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 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 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).
Much of the work on the Red Cap property has focused in the area east of Red Cap Lake known as the Slope zone, presumed to represent the core of a high-level porphyry copper-molybdenum system. The Slope zone is located just above the Silica Cap zone in elevation and just below the Ridge zone (MINFILE 104K 085). The area is poorly exposed and contains a substantial molybdenum in-soil anomalous zone. The Slope zone was tested in 1981 by 5 drillholes (holes 81-3 to 7) and 6 six short vertical x-ray drillholes in 1971. See the history discussion (1981) below for drill results.
Peripheral to the main granodiorite intrusion, extensive zones of hornfelsing are accompanied by hydrothermal alteration and stockwork veining, ostensibly within altered andesitic rock, originally mapped as rhyolite. In the Slope Zone, sheeted to stockwork quartz veining is intense, extending southwest through the “Copper and Moly creeks” areas. Pyrite is the most common sulphide present, occurring as fine disseminations and as fracture fillings with or without quartz. In the Slope zone, chalcopyrite is noted to be common in areas associated with intense quartz flooding. Molybdenite is widely distributed in narrow quartz veinlets. Although masked on surface by oxidation, potassic alteration characterizes the core of the porphyry system as evidenced by the presence of secondary biotite and k-feldspar along with accompanying silica and tourmaline. Pyrite and chlorite at the margins of the intrusion indicate a propylitic alteration halo.
The Slope, 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 and possibly Moly and Copper creeks (Silica Cap zone) 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.
Little is known about the early history of the Red Cap area. The prospect was mentioned in the 1930 and 1931 Minister of Mines Annual Reports with prospecting and sampling reported for 1931.
In 1971, Archer Cathro and Associates staked the Mike claims over the Red Cap showing and drilled six short vertical holes totaling 26.8 metres (88 feet) in an area located about 1.5 kilometres east of the southern extent of Red Cap Lake (Assessment Report 3670). Although these holes were unable to penetrate through the surface oxidation to fresh bedrock and despite poor core recoveries, the presence of molybdenite in geochemically anomalous amounts was confirmed. No core was recovered in hole one. Primary copper and silver were not reported but were thought to have been depleted by surface oxidation.
In 1979, Omni Resources Inc. undertook a helicopter supported exploration program in the Red Cap area with a base camp situated at Border Lake, 30 kilometres south. Omni staked the Red Cap showing and prospected the area.
In 1980, Omni Resources completed 43.45 kilometres of grid line consisting of 100 metre lines and 50 metre stations. Some geological mapping was carried out and a total of 723 soil samples (talus fines) were collected from this grid (Assessment Report 8959). These samples were analyzed for copper, molybdenum and silver. Combined with the mapping results, the geochemical pattern was used to define a large porphyry copper-molybdenum system with associated gold values. The grid area encompasses the Ridge zone and East Cirque zone along with a number of mineralized showings. These showings include the Berg, Bergie, Goat, RV, and Ridge Extension zone (Assessment Report 18803, Figure 3). In September 1980, an NQ diamond-drill hole was completed to a depth of 172.3 metres (Assessment Report 9246). This hole tested the Bergie showing within the East Cirque zone. Three mineralized sections were intersected. The first consisted of 90 centimetres of sheared rhyolite breccia with 20 to 30 per cent pyrite and arsenopyrite, 1-2 per cent sphalerite, and 0.5 per cent chalcopyrite. The second section was a narrow interval within rhyolite breccia with 10 per cent pyrite and 1-2 per cent arsenopyrite with minor sphalerite. The third mineralized intersection was over 5.30 metres in length and contained about 5 per cent total sulphides.
In 1981, a series of seven NQ diamond-drill holes totaling 1203.6 metres were drilled by Omni Resources from four drill sites and varied in depth from 132.3 to 260.0 metres (Assessment Report 10452). The holes were designed to test the Ridge zone and a large molybdenum soil geochemical anomaly called the Slope zone. The Ridge zone was defined by re-analysis of soil samples collected in 1980 for gold. The best hole in this series was RC8l-l that tested a copper-molybdenum-silver anomaly. This hole intersected 9.2 metres grading 1.59 per cent copper and 59.65 grams per tonne silver. The best intersection on the Slope zone was 125 metres grading 151 parts per million molybdenum.
In 1982, a single diamond-drill hole was completed by Omni Resources Inc. in order to test highly anomalous (up to 3500 parts per billion) gold-in-soil geochemical values (Assessment Report 11089). This hole was completed in a massive unfractured rhyolite and totalled 31.2 metres in length. This rhyolite hosted a 2.15 metre drill section of massive sulphide material assaying 1.84 per cent copper and 96.0 grams per tonne silver. This mineralized interval included a 60 centimetre section grading 3.17 per cent copper, 169.37 grams per tonne silver and 0.14 per cent zinc with the best gold assay of 0.27 gram per tonne. The source of the original high gold geochemical anomaly remains unexplained.
No further work was completed on Omni Resources’ Red Cap Property until 1988 when an airborne geophysical program totaling 92 line kilometres of airborne magnetic and VLF-EM survey was flown (Assessment Report 17839). A number of magnetic anomalies and conductors were detected by this survey. In the East Cirque area, airborne conductors were found to be coincident with precious metal bearing vein systems. The 1988 summer exploration program focused on the precious metal content of the Red Cap prospect and exploration was centered around the northern portions of the prospect peripheral to the main copper-molybdenum mineralization (Assessment Report 18803). The program consisted of geological mapping, prospecting, channel sampling of mineralized zones and minor grid soil (talus fines) sampling. A total of 205 rock, 242 soil (talus fines) and 16 silt samples were collected. Assays of up to 34.99 grams per tonne gold, 1390 grams per tonne silver, 9.85 per cent lead, 9.33 per cent zinc and 1.71 per cent copper were obtained from rock samples.
A 1990 exploration program was conducted on the Red 1 and 2 claims owned by Erik Bergvinson (Assessment Report 20325). Work occurred immediately north and west of Red Cap Lake and comprised geological mapping, prospecting and rock and contour soil sampling. A total of 11 rock samples were collected from float and outcrop. Total samples collected numbered 48 from 1475 metres of line.
In 1991, exploration on the Red Cap Property by operator International Corona Corporation (owner, Omni Resources) consisted of prospecting, installation of a modified grid and extensive rock sampling (Assessment Report 21687). A Corona crew visited the property in late June 1991 to examine gold and base metal distribution on the ridges north of Red Cap Lake. In general, surface sampling failed to return significant assays from most of the grid areas. Of the 160 rock samples collected, only four yielded gold values in excess of 0.34 gram per tonne.
The Omni Resources ownership of the property ended prior to 1998, at which time Xplorer Gold Corp. was in control of the Red Cap prospect.
In 1998, ground total field magnetic and horizontal loop electromagnetic (HLEM) surveys totaling 1.575 line kilometres were conducted on Xplorer’s Red Cap Property (Assessment Report 25459). The surveys were conducted to delineate the flat-lying volcanics and to possibly locate mineralization associated with this unit based on the geophysical responses. A total of 1.575 line-kilometres were gridded and surveyed on the Kap grid. Anomalies RC-1, RC-2, and RC-3 on the Kap grid were identified at the southwest portion of the grid. All anomalies were considered weak. Also in 1998, total magnetic field and VLF-EM surveys totaling 51.3 line-kilometres were conducted on the Red Cap Property for Xplorer Gold Corp. to locate structures or rock units hosting auriferous sulphide mineralization (Assessment Report 25745). A grid consisting of 51.3 line-kilometres was installed; the grid was located east of Red Cap Lake and northwest of Mount Lester Jones. The magnetic survey identified two granodiorite plugs in the southern part of the grid and the VLF-EM survey identified three conductors. A twelve-hole drilling program was also completed on the property in 1998 (Assessment Report 25970). A total of 1752 metres of slim-wall B core was completed during this program. Several mineralized intersections of note were obtained. A 3 metre interval in hole LJ-98-5B assayed 3.7 grams per tonne gold and 26.0 grams per tonne silver. In hole RV-98-10, there were two significant intervals: the first assayed 12.05 grams per tonne gold and 49.5 grams per tonne silver over 7.15 metres; the adjacent intersection assayed 2.50 grams per tonne gold and 18.37 grams per tonne silver over 4.73 metres.
The property was acquired by Xplorer Minerals Inc. in 2005. In 2006, the company carried out an exploration program of prospecting, geological mapping, and stream sediment sampling over a wide area of the property, as well as geophysics and MMI (mobile metal ion) soil geochemistry over a grid put in about one kilometre southeast of Red Cap Lake (Assessment Report 29190). The grid consisted of four lines with a line separation of 100 metres and a station interval of 25 metres. The total amount of survey line was 2850 metres. The size of the grid was limited by rock cliffs and talus slides. Work carried out on the grid was geophysics which consisted of induced polarization (IP), resistivity, and magnetic surveying, as well as MMI soil geochemistry sampling. The exploration program revealed two main MMI anomalies that directly correlate with IP chargeability anomalies. The northern IP/MMI anomaly, occuring over the northern region of the Silica Cap zone and the southern portion of the Slope zone, is mainly a molybdenum/gold/copper anomaly containing anomalous values in silver. The minimum size is 300 metres in an east-west direction by 300 metres in a north-south direction with it being open to the east, west, and north. The inversion IP sections indicate the depth to the causative source is 40 to 60 metres. The MMI results also show anomalous cerium values correlating with anomaly A which indicates that the causative source of A is associated with an acid intrusion. Geological knowledge of the area suggests that this could be a granodiorite. The second IP/MMI anomaly, south of the Silica Cap and Slope zone and having no previous documented exploration history, is principally a lead/zinc anomaly also with correlating anomalous values in silver. The size of this anomaly is a minimum 300 metres in an east-west direction by up to 200 metres in a north-south direction. It is open to the east and west. The inversion IP section indicates that the causative source is at about a 40 to 80-metre depth. The Silica Cap located along the northern section of the grid is reflected by a resistivity high.
See historically and geologically related Red Cap prospects for further detail. These include: Ridge zone (MINFILE 104K 085), East Cirque, Silica Cap, Couloir and Abandon.
