The Tachi area is underlain by Permian to Triassic Takla Group rocks and Lower to Middle Jurassic Hazelton Group schistose volcanics comprised mainly of andesitic flows, tuff and breccia that strike northwards and dip steeply east. These rocks are intruded by granodiorite of the Middle Jurassic Spike Peak Intrusive Suite, which underlies the area in the area of the prospect.
The Spike Peak intrusions are comprised mainly of granodiorite to quartz monzonite. They are crosscut by biotite-quartz-feldspar porphyry dikes that have irregular, commonly brecciated contacts and strike predominantly east.
Alteration products include sericite on feldspars and incipient chloritization of biotite. More altered varieties of the intrusive exhibit porphyroblasts of potash feldspar plus epidote, chlorite, potash feldspar and magnetite in and marginal to numerous fractures.
Sulphide mineralization, consisting of pyrite, chalcopyrite, and molybdenite appears to be widespread marginal to the biotite-quartz feldspar porphyry dikes. In general, the molybdenum is restricted to potash feldspar rimmed fractures, while chalcopyrite occurs both in fractures and as disseminations in both the granitic rocks and the porphyries. Precious metal values were noted in the contact zones.
Copper mineralization and related secondary copper oxide minerals and other sulphides observed on the GD claims include, in order of abundance; malachite, chalcopyrite, magnetite, pyrite, molybdenite, azurite, and bornite. These minerals are consistent with a widespread copper/molybdenite porphyry system on the GD claims. The mineralized porphyry system extends, in areas mapped, from Tachek Creek north to Tachek Creek south, a north-south distance of approximately 1125 metres.
Copper mineralization is hosted almost exclusively within Middle Jurassic Spike Peak Intrusive Suite quartz monzonite rocks. Three types of controls on copper mineralization were observed within the quartz monzonite intrusive rocks on the GD claims:
1) Fracture controlled copper mineralization consisting of malachite and chalcopyrite is most common on the GD claims. Less common are fractures containing molybdenite and azurite that were mapped in Tachek Creek north and to a lesser extent in Tachek Creek south. Magnetite is common in Tachek Creek north (disseminated/along fractures) and is a common constituent of potassic alteration zones in porphyry deposits. The hydrothermal deposition in fracture fillings indicate the presence of base metals thus there is a possibility of porphyry type deposition
2) Fault controlled copper mineralization consisting of chalcopyrite, malachite, molybdenite, azurite and associated magnetite was observed in both north and south Tachek Creek but is most common in the northern regions of Tachek Creek north. Numerous faulting on the GD property has localized high concentrations of copper mineralization along fault planes extending up to approximately 2 metres into the quartz monzonites on either side of the fault plane. These zones are typically gossanous and contain trace to 2 per cent disseminated chalcopyrite, weak to strong malachite (to a lesser extent azurite), and trace-1 per cent molybdenite. High concentrations of blebby magnetite are common within these faulted zones. Pinkish zeolite and very weak calcite fill fractures near strongly faulted zones.
3) Dikes and dike swarms usually occur in zones of weakness produced by earlier faulting and tend to concentrate copper mineralization. Here copper mineralization and sulphides (chalcopyrite, pyrite, molybdenite, and malachite) increase marginal to porphyry and diabase dikes. These dykes have sharp contacts and chill margins. Trace amounts of copper mineralization consisting of malachite and chalcopyrite were seen in diabase and crowded porphyry dikes as disseminations and along fractures.
Two types of rare mineralized veinlets were mapped at Tachek Creek north. Firstly, a single quartz-chlorite veinlet approximately three centimetres wide contained trace chalcopyrite. The quartz ranges in texture from massive white quartz to vuggy-drusy quartz. Secondly, a single vuggy-drusy quartz carbonate veinlet mineralized with malachite and chalcopyrite was mapped and is two centimetres wide. Semi-massive to massive chalcopyrite stringers and blebs about 1-2 centimetres wide were observed in float within Tachek Creek north.
WORK HISTORY
In 1968, mineralization was identified by prospectors in Tachek Creek, and 170 claims were staked by Noranda Exploration Limited. Exploration activities during 1968 and 1969 consisted of geological mapping, geochemical (soil and silt) analysis, geophysical surveys (induced polarization and magnetic and electromagnetic), 1725 metres of percussion drilling and 1,015 metres of diamond drilling. The best assays obtained in the drill program were reported from hole 32 with 3.1 metres of 0.25 per cent copper and from hole 31 with 3.1 metres of 0.62 per cent copper (as reported in Assessment Report 34333).
During October to December 1968 and March to July 1969, a geochemical soil survey was conducted by Tro-Buttle Exploration Ltd. A total of 75 line-kilometres (47 line-miles) were blazed, picketed and flagged, which resulted in the collection of 1267 soil samples (Assessment Report 2095). Of the 1267 samples, 59 yielded molybdenum values above zero and 169 samples were above the threshold of 30 parts per million for copper and appeared discontinuous.
In 1970, Taseko Mines Limited drilled 3 diamond drill holes for a total of 305 metres were completed, though the original source of this data is not known.
In 1970, Tro-Buttle Exploration Ltd conducted approximately 39 line-kilometres of soil surveying which resulted in the collection of 680 soil samples. A total of 29 samples above 61 parts per million copper and 24 samples above 3 parts per million molybdenum were obtained, however the results were intermittent (Assessment Report 2727; Assessment Report 33645).
In 1972, Twin Peak Resources Ltd and Cobre Exploration Ltd conducted an exploration program. Twin Peak Resources Ltd completed an airborne magnetic survey for a total area of approximately 30 square kilometres. The results revealed a prominent north-easterly trend in the eastern portion of the study area and subtle northerly trend in the western portion of the study area (Assessment Report 4427).
In 1973, Perry, Knox and Kaufman Inc. conducted a time-domain induced polarization (IP) survey to search for economic concentrations of disseminated mineralization at a geologic contact between volcanic rocks and intrusive rocks (Assessment Report 4479). Two anomalous zones were identified and recommended for future drill testing within the south and central areas of the property.
In 1973, Amoco Canada Petroleum Co. Ltd. carried out geochemistry and geophysics and completed 500 metres of diamond drilling in three holes, of which, no results were reported. (Assessment Report 33645).
In 1982, an exploration program was completed by Dancer Energy and Resources Limited which consisted of soil sampling and geological mapping. The resulting grades range as high as 1 per cent copper and 0.9 per cent molybdenum (Assessment Report 10862).
In 1987, Gerard Auger conducted the exploration program that consisted of prospecting, geological mapping and the collection of rock samples for geochemical analysis. Samples from granitic rocks contained 126 to 214 parts per million of copper, molybdenum values up to 0.17 per cent, and one sample with 1.27 grams per tonne of gold (sample GD-2) (Assessment Report 16874).
From 1989 to 1992, exploration activities conducted by Nick Carter consisted of prospecting, rock sampling and geological mapping. A follow up chip sample to GD-2 collected in 1988 yielded a copper value of 0.0196 per cent, a molybdenum value of 0.099 per cent, and 4.9 grams per tonne gold (Assessment Report 19556). In 1990, VLF-EM survey was completed over 12.5 kilometres, which did not identify any significant anomalies (Assessment Report 20794). In 1991, percussion hole cuttings and drill core samples from Noranda’s 1968 and 1969 drill programs were sampled and results indicate low grades, but apparently widespread copper values as well as anomalous gold values in two areas of the property (Assessment Report 22025).
In 1993, Cominco conducted an Induced Polarization/Resistivity survey to follow-up some of the previous alteration and sampling. Findings suggest the presence of a copper-molybdenum porphyry system (Assessment Report 33645).
Hudson Bay Exploration and Development Co. Ltd. began prospecting and following up on Cominco’s targets during exploration programs in 1995 and 1996. In 1997, 19 kilometres of line cutting, 16 km of ground electromagnetic (EM) and magnetic surveys were completed, and 68 soil samples were collected for geochemical analysis. The EM survey defined two parallel conductors and all soil samples assayed at background levels (Assessment Report 33645). In 1998, an additional 16 kilometres of geophysical and line cutting was carried out. In 1999, seven diamond drill holes we completed for a total of 1,094.5 metre drilled, with hole LEN-004 yielding anomalous values in base and precious metals (Assessment Report 26329).
In 2006, NXA Inc. completed an exploration program consisting of 15 kilometres of line cutting, IP and magnetic geophysical surveys, prospecting and geochemical soil surveying. Within the IP surveys, areas with a low magnetic susceptibility and low resistivity are interpreted as possible zones of mineralization (Assessment Report 33645).
In 2010, exploration activities by Altiplano Minerals Ltd. consisted of geological mapping, prospecting and rock/soil geochemical surveys over portions of the GD Property, especially in the Tachek Creek area. Programs focussed on following up previously identified anomalies and areas of interest. Soil sampling consisting of the collection of 520 samples was conducted on two grids that covered. Rock sampling consisted of the collection of 84 continuous rock chip samples, 2 float rock samples and 2 grab rock samples. Sampling was focussed on the Tachi (093L 144).
During 2012, Rio Minerals Limited and Apex Geoscience Ltd. on behalf of Altiplano Minerals Ltd. carried out a field program of continuous rock chip sampling on trenches excavated in 2010 (Tachek Creek North and South), extended the 2010 soil grid, and performed spot checks and horizon sampling of several previously noted anomalous areas. The field program consisted of the collection of 18 continuous rock chip samples and 175 soil samples. Several continuous rock chip samples returned elevated values of copper and molybdenite. In general, wide spread copper mineralization in exposed outcrop was observed extending from Tachek Creek north to Tachek Creek south, a distance of 1125 metres. Sampling also occurred in the Gold Dust (093L 315) area.
In 2012, an aeromagnetic program was conducted over the Flute and Lennac properties by Riverside Resources (BC) Inc. The total covered area was 813 square kilometres and the total survey line coverage was 4,444 line kilometres (Assessment Report 33032, 33707F). The Tachi occurrence and area was covered by this survey though not part of the Lennac or Flute properties. A report on the survey by Riverside Resources (BC) Inc is found in Appendix D of Assessment Report 33032. However, maps showing the Total Magnetic Intensity and First Vertical Derivative of TMI are found in Assessment Report 33707F.
During the 2013 field program on Altiplano Minerals Ltd’s GD Property in central British Columbia, six rock samples and 186 soil samples were collected, which have outlined and further expanded existing copper, gold, and molybdenite anomalies. The soil lines were in the vicinity of the Jill showing 093L 242).
