The Alexis occurrence comprises copper-mercury mineralization in a broad alteration zone on a ridge 4 kilometres west of the centre of Chilko Lake. The mineralization was discovered in 1980, and was worked on intermittently in the 1980's, including 287 metres of diamond drilling over 3 holes.
The Alexis area lies within the Tchaikazan fault zone, a regional northwest-striking strike-slip fault (Geological Survey of Canada Map 5-1968, Paper 68-33, Open File 1163). It is located in a Cretaceous overlap assemblage, 25 kilometres northeast of the main margin of the Jurassic to Tertiary Coast Plutonic Complex (Geological Survey of Canada Open File 1163, Map 1713A). The fault zone is a series of subparallel faults, several kilometres wide, and was probably active in the early Tertiary (Geological Survey of Canada Open File 1163). The Alexis occurrence is hosted in a narrow, fault-bound belt of Upper Cretaceous rocks of the Powell Creek Formation. A northwest-trending fault-bound belt of the Lower Cretaceous Tchaikazan River succession (volcanic facies) occurs about 1 kilometre to the southwest. There are numerous smaller transverse, northeast-striking faults.
Local mapping indicates dacitic, andesitic and basaltic volcanic breccia and tuffs, and sandstone, grit, greywacke, siltstone, mudstone, argillite and chert-pebble conglomerate. The rocks are intruded by hornblende-plagioclase porphyritic dikes and sills, and by small dioritic stocks, probably related to the Upper Cretaceous to Paleocene Bendor Suite. Bedding strikes northwest and generally dips moderately northeast. Shear fractures are widespread.
The Alexis occurrence is marked by strong and pervasive alteration, brecciation, veining and mineralization; chalcedonic silica and vuggy vein textures are present in the vein breccias. These characteristics have been interpreted to fit the upper zone of the British Columbia epithermal model, related to fracturing and metal-rich hydrothermal activity in the Tchaikazan fault system (Bulletin 81; Assessment Reports 9535, 13892).
The alteration zone is discontinuous over an area about 1000 by 300 metres, centred on the Knob showing. Carbonate alteration is the most widespread and pervasive, and is associated with intense brecciation and veining of the host rocks, the disruption of which is so strong that they are described as "heterolithic breccias" (Assessment Report 9535). White calcite is dominant, although iron-bearing carbonate is common, giving rise to prominent limonitic or ankeritic areas of oxidation. At its most intense, carbonate has replaced the original mineralogy of the volcanic or sedimentary protoliths. Individual carbonate veins have a variety of orientations, but most strike northwest and dip steeply. Barite veins are also reported (Assessment Report 13892).
Silicification and quartz-calcite veins and stockworks are less common but are intensely developed in a 10 by 10 metre zone at the Knob showing, which contains most of the mineralization. Argillic alteration or "bleaching" of volcanic rocks is also present in the vicinity, with the production of kaolinite and calcite (Assessment Report 11661). Minor epidote and sericite alteration has been recorded in drill core (Assessment Report 13892).
Visible mineralization occurs mainly at the Knob showing and consists of cinnabar associated with calcite veins, malachite and azurite, and locally tennantite, tetrahedrite, realgar, hematite, aragonite, dickite and rarely stibnite (Bulletin 81; Assessment Reports 9535, 11661). Pyrite, pyrrhotite and arsenopyrite have been recorded in drill core (Assessment Report 13892). Samples of the mineralization have yielded assay values of up to 1.47 per cent copper, 0.39 per cent antimony and 16.5 grams per tonne silver (Assessment Report 9535). Lithogeochemical analyses include 27 grams per tonne silver and 0.8 per cent copper from a single sample (Bulletin 81).
Another showing, the Ridge showing, occurs 500 metres west of the Knob showing and is defined mainly by an arsenic anomaly (Bulletin 81; Assessment Report 11661). It is similarly brecciated and carbonate-altered, and contains arsenopyrite and alunite, as well as malachite and cinnabar (Assessment Reports 10608, 11661).
Assay values and rock and soil geochemical analyses are anomalously high but erratic in the area of the Alexis occurrence, particularly in mercury, arsenic, antimony, copper and zinc (Bulletin 81; Assessment Report 9535). Gold is anomalous but not high. There is a positive correlation between mercury lithogeochemical values (up to 0.45 per cent) and the degree of mineralization (Bulletin 81); mercury is considered an important pathfinder element (Assessment Report 9535). The erratic values are not inconsistent with this type of high-level, highly permeable environment in which leaching processes have redistributed metals, resulting in secondary enrichment or dilution of values (Assessment Report 9535).
Past work has generally concluded that more exploration of the extent and vertical zonation of mineralization in this system, particularly by deeper diamond drilling, is warranted to properly ascertain its economic potential, especially in terms of gold and silver (Bulletin 81; Assessment Report 18162). Other, similar showings of mineralization are known along the strike of the Tchaikazan fault zone which have not been explored to date. For example, the copper-mercury Stowe showing (092N 043) is 3 kilometres southeast of the Alexis, and traces of mercury mineralization exist 1.5 kilometres to the northwest (Bulletin 81).
WORK HISTORY
In 1981, the original 34 units of the Alexis 1 through 16 and Sunshine 1 and 2 were staked by J. William Morton. In the same year 182 soil and 77 rock chip samples were collected for analysis (Assessment Report 9535, 10608). A limited induced polarization survey over 2 known showings was completed along with 287 metres of diamond drilling. No work was done in 1982. Homestake Mineral Development Company secured an option in 1983 and added 36 more units in the ALX 1 and ALX 3 claims. Imperial Metals became the owner while Homestake remained the operator. In 1983, 3,750 metres of grid line on the Alexix 1-4, 7 and 16 were run followed by geological mapping (1:2500) (Assessment Report 11661). Further mapping at 1:10,000 scale was completed over Alexis 2-6, 9, 11, 15 and 16. Collection of 62 rock chip samples was completed over Alexis 1-7, 9-11, 13, 15 and 16 claims. Collection of 21 soil fines (talus fines) occurred over the Alexis 2, 11, 15 and 16 claims. An Induced Polarization and Resistivity survey has been completed on the Alexis property, on behalf of Imperial Metals Corp (Assessment Report 11934). The 1983 geophyiscial survey detected three zones of weakly to moderately anomalous IP effects as well as two isolated IP anomalies on the western end of Line 2+50N. None of these features appear to correlate directly with the mapped position of the vein of calcite alteration, which suggests that non-conductive, and therefore nonpolarizing carbonate material only constitutes the vein.
In 1985, Imperial Metals Corporation owned and operated the Alexis claims. Drill core originating from a 1981 drill program was selectively resampled and geochemically analyzed (Assessment Report 13892). The drill core is all BQ in size and was all stored at the Bunting Lake Ranch near 150 Mile House. DDH 1, DDH 2 and DDH 3 were undertaken on Alexis 1 and Alexis 2 claims. Anomalous mercury values occurred in several samples although precious metals results were low.
In 1986, owner/operator of the Alexis claims Jim Morton retrieved eight samples originally analysed in 1981 (Assessment Report 15266). These retrieved samples were geochemically assayed using neutron activation techniques. Silicification and carbonatization of andesitic volcanics was reported to accompany antimony mineralization. Samples were originally from the Alexis 1 and Alexis 2 claims.
In 1987, a carbonate alteration zone was, examined and sampled on a ridge and where it occurs in an incised creek bed. This alteration zone had been sampled by the B.C. Ministry of Mines and Petroleum Resources during their 1987 geochemical survey when they collected 11 samples in the Alexis area from which values up to 0.138 gram per tonne gold in sample RM180 and 27.0 grams per tonne silver, 0.8 per cent copper and 0.45 per cent mercury in sample RM186 were obtained (Open File 1987-14).
The 1988, Eastfield Resources program traced this intense alteration zone for a projected distance of 470 metres and established its width to be at least 150 metres (Assessment Report 18162). This zone remained open to the north and south. Eastfield collected 11 rocks samples (BXR -1 to BXR-11) were collected. Sample BXR-1 gave similar similar assay geochemistry (with about half the grades) as 1987 sample RM186. Sample BXR-1 is descrbed as a carbonate-rich vein breccia with pervasive carbonate flooding, having copper carbonate stain and visible cinnabar. The vein had an 087 degree strike with 30 degree south dip.
