The Thezar 81 (East) occurrence is located approximately 13 kilometres southwest of Topley Landing and 2 kilometres north of Lennac Lake, about 54 kilometres east of the community of Smithers.
Regionally, the area is underlain by Lower Jurassic Hazelton Group volcanics composed of andesite, andesitic to rhyolitic tuff, breccia, minor argillite and conglomerate and dips gently northeast. The volcanics are intruded by northeast trending quartz plus feldspar plus biotite plus hornblende porphyry bodies of the granodioritic Late Cretaceous Bulkley Plutonic Suite. East of the property, Triassic Takla Group volcanics discordantly overlie the Hazelton Group. The Takla rocks are composed of chert, volcanic and sedimentary breccia, massive dacite to andesite flows and tuff. North of the property, Cretaceous sediments overlie the Hazelton Group. South of the property, the Hazelton Group is overlain by Tertiary Ootsa Lake and Endako groups volcanic rocks.
The East zone is characterized by a series of copper showings in the Hazelton rocks (Telkwa Formation). Typically, the volcanics are weakly propylitized, weakly to intensely bleached and pyritic (2 to 4 per cent). Bleaching is due to a combination of argillization and silicification of the rock. Fine to medium-grained pyrite, chalcopyrite and magnetite with minor hematite and sphalerite(?) occur predominantly along fractures or as disseminations in the hostrock. A stockwork of mineralized quartz-calcite veins and veinlets crosscut the volcanics and host pyrite and chalcopyrite mineralization. Malachite staining occurs along fractures. Mineralized fracture coatings and veinlets are associated with chlorite-epidote alteration superimposed on biotite hornfelsed Telkwa volcanics.
In 1971, the East zone was initially discovered by Amax Exploration Inc. and staked as part of the Thezar claims. In 1972, the company performed a 470-sample soil survey across the East (093L 191) and West (093L 190) zones. Sporadic copper anomalies were only found in material above mineralized bedrock (Assessment Report 32831). In 1973, Amax Exploration Ltd. drilled eight percussion-drill holes and completed an induced polarization (IP) survey indicating a potential mineralized zone approximately 600 by 800 metres in size. The best results included 0.17 and 0.11 per cent copper over 90.5 and 86.9 metres, respectively; grades are generally less than 0.1 per cent copper. Amax did not complete any further work and later allowed the claims to lapse (Assessment Report 22181).
In 2012, two holes tested the continuity of known mineralization at the East zone. The drillholes were chosen to test both the strong magnetic high halo and magnetic low centre of a “doughnut” magnetic anomaly - a geophysical signature favourable for porphyry systems - which underlies the East zone. Drillhole LLDH-12-003, drilled beneath a historic reverse circulation (RC) hole which yielded narrow copper mineralization, intersected only localized copper mineralization hosted as blebby and disseminated chalcopyrite in late quartz and carbonate veinlets within chlorite, epidote, magnetite altered crystal lithic tuff. The alteration assemblage is typical of a distal propylitic alteration halo within the Lennac Lake porphyry systems. Drillhole LLDH-12-004 targeted the magnetic low centre within the doughnut-shaped magnetic feature and intersected strongly clay-sericite altered quartz, biotite, feldspar porphyry with two phases of strong stockwork veining. Fine, wormy, quartz veins are cut by planar, barren quartz vein stockwork throughout the hole. Although the intense stockwork veining was encouraging, the lack of sulphide suggests the intrusive phase was not intruded under favourable conditions for copper porphyry mineralization. Only very localized molybdenite and rare chalcopyrite veinlets were intersected in LLDH-12-004.
The most advanced prospect on the Lennac property is the Lennac Lake copper-molybdenum prospect which was first discovered by Amax Exploration Inc. in 1971 staked as the Thezar claims (Assessment Report 3807) (093L 190, 191). Work on the property defined four areas of low grade copper mineralization. After completing an IP survey (Assessment Report 3808), Amax drilled 44 percussion holes in 1973 (Silversides, 1973 (internal report)) and five diamond-drill holes in 1974 (Assessment Report 5031). The best results included 0.17 and 0.11 per cent copper over 90.5 and 86.9 metres, respectively; grades are generally less than 0.1 per cent copper. Amax did not complete any further work and later allowed the claims to lapse (Assessment Report 22181). At the same time, British Newfoundland Exploration Ltd. drilled 11 percussion- and three diamond-drill holes on the Jacob showing (093L 243) south of the Thezar claims. In both cases, the claims lapsed. Cities Service Mineral Corporation completed an 1100-sample soil geochemical survey targeting a favourable magnetic anomaly centred approximately 2 kilometres to the northwest of the Lennac Lake prospect drilled by Amax. The survey yielded only lower amplitude spot copper and zinc anomalies (Assessment Report 4192).
In 1981, Pola Resources completed further prospecting and a small ground electromagnetic (EM) survey over areas of interest identified by Cities to the northwest of the Lennac Lake prospect. A single potassic altered quartz, feldspar, biotite, hornblende porphyry outcrop was identified hosting chalcopyrite and pyrite (Assessment Report 9934).
In 1990, L. Bourgh re-staked the property and it was optioned to Kennecott Exploration (Canada) Ltd. Kennecott completed geological mapping, prospecting and trenching and found additional copper showings on the east side of the property (the Southeast zone, 093L 338) (Assessment Report 22181). Cominco Ltd. optioned the property in 1993 and completed additional prospecting, soil geochemistry and trench sampling in the Southeast zone (Assessment Report 23048).
Hudson Bay Exploration and Development held the property in 1998 in which a ground EM survey totalling 25.5 line kilometres was completed. After this survey, it was concluded that grids should be investigated for outcrop and soil geochemistry in the vicinity of several EM anomalies (Assessment Report 25628). However, Hudson Bay Exploration dropped the claims in July 2004.
Six two-post legacy claims were staked over the Southeast zone in September 2004 by D.G. MacIntyre and V.H. Parsons of Victoria. Additional claims to cover the original Thezar and Jacob showings were added in 2005 when electronic staking was inaugurated. The original two-post claims were subsequently converted to cell claims. In 2004, a broad orientation soil survey was completed at the Southeast zone to determine if soil sampling was an effective tool. Eight samples were taken which yielded anomalous copper and silver (Assessment Report 27987).
In February 2007, Dentonia Resources Inc. optioned the Lennac Lake property with D.G MacIntyre and V.H Parsons. The main focus of Dentonia’s exploration program was the Southeast zone, which was discovered in the early 1990s, and had not been previously drill tested. In 2007, a total of 639 metres of AQ diamond drilling in nine short drillholes (none of which exceeded 100 metres in vertical depth) were completed in the Southeast zone. Results of this drilling were disclosed in news releases by Dentonia from November 16, 2007 and January 26, 2008. This drilling indicated anomalous concentrations of molybdenum, copper, silver and to a lesser extent gold hosted in clay altered volcanic rocks and feldspar porphyry dikes over a distance of 800 metres (Assessment Report 29459). Dentonia was encouraged by the extensive alteration and fine grained sulphide mineralization intersected in nine short AQ drillholes. A total of 2650 metres of NQ diamond drilling was completed in nine drillholes in 2007 and January 2008. Dentonia subsequently dropped its option on the property.
In 2012, Riverside Resources (BC) Inc. completed geological mapping at the Lennac Lake, Cougar (093L 193) and Mouse properties with focus on compiling alteration data. Regional outcrops outside of the main target areas were also investigated. The mapping area was limited by sparse outcrop exposure. A total of 61 rock chip samples were collected within the Flute and Lennac claim blocks. The majority of these samples were from mineralized and altered outcrop and subcrop near the the Lennac Lake copper showings. Rock chip samples near the West zone yielded up to 0.22 per cent copper from a sericite altered quartz, biotite, feldspar porphyry with quartz stockwork veining (Assessment Report 33707). Reverse circulation drilling was completed at the Flute and Lennac properties.
In 2012 and 2013, Riverside Resources (BC) Inc. conducted a percussion drill program in a significant area north of Fulton Lake (Assessment Reports 33707 and 34591). The purpose of the drill program was to penetrate glacial cover and test the bedrock in target areas to determine if further work including diamond drilling was worthwhile. Drilling was located on pre-existing access roads and trails. In 2012, a total of 96 vertical drillholes for 1997 metres at 93 sites were completed and in 2013 a further 77 vertical percussion drillholes totalling 1655 metres were drilled (Assessment Report 34591). Three new intrusive centres with anomalous copper and gold with porphyry-style alteration were discovered on the Flute property as result of the reverse circulation drilling and sampling.
The purpose of the RC drill program was to penetrate glacial cover to test the bedrock in target areas to assess validity of further diamond drilling. A total of 96 vertical drill holes for 1997 metres at 93 sites were completed targeting the Lennac Lake prospects, the Cougar showing and Mouse showing. RC drilling at the West zone at Lennac Lake aided in confirming the extent of mineralization while constraining the extent of alteration haloes of the known porphyry system. At the East zone, RC drilling intersected sporadic zones of copper-molybdenum mineralization often correlating with localized zones of potassic altered fine-grained intrusive rocks.
Exploration diamond drilling at the Lennac Lake prospects in 2012 included two holes at the West zone totalling 800.4 metres and two holes at the East zone totalling 678.65 metres of NQ diameter core. An aeromagnetic survey was conducted, totalling 158.5 kilometres (Assessment Report 33302).
In 2012, an aeromagnetic program was conducted over the Flute and Lennac (093L 190, 191, 193, 243, 338) properties having a total area coverage of 813 square kilometres. The O occurrence was covered by this survey. Total survey line coverage is 4444 line kilometres. 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. These maps indicate that the following MINFILE occurrences have been covered by the survey: Tachi (093L 144), Guess Creek Coal (093L 151), O (093L 163), Mine (093L 164), Alp (093L 167), Thezar 75 (West) (093L 190), Thezar 81 (East) (093L 191), Cortina (093L 192), Cougar (093L 193), Totem (093L 199), Red (093L 210), Donna (093L 212), FG (093L 213), Badge (093L 215), Sat (093L 224), Pro (093L 225), Jill (093L 242), Jacob (093L 243), Cart (093L 306), Chris (093L 307), Calcite (093L 308), Gold Dust (093L 315), and Suratt (093L 338).
Three doughnut-shaped magnetic features were identified from the aeromagnetic survey, two of which correlate with copper-molybdenum porphyry-style mineralization at the East and West zones at Lennac Lake. The third doughnut feature may represent a barren phase as suggested by limited outcrop exposure and lack of an anomalous soil geochemical signature. Several circular features favourable of a porphyry-style signature were identified within regions of structural complexity and may represent intrusive centres and targets for copper porphyry-style mineralization warranting follow-up work.
In 2013, Riverside Resources (BC) Inc. completed smaller soil sampling grids at the Betty, Red Top, Cougar and Baboon Lake target areas with an orientation survey completed over the known porphyry mineral occurrences at the West, East and Southeast zones of Lennac (Assessment Report 34591). A total of 720 broadly-spaced Ah horizon samples were collected on the Flute and Lennac properties. Sampling grids were expanded with 250-metre spacing at Red Top and 500-metre spacing on the newly acquired O target (093L 163).
In 2013, a total of 9.25 kilometres of IP surveying was completed. Through a combination of top-of-bedrock RC drilling and regional Ah soil sampling, the 2013 field season was successful in identifying new target areas for calc-alkalic porphyry-style mineralization (Assessment Report 34591). These included the MSZ (Massive Sulphide zone).
In 2017, Rich River Exploration Ltd. completed a program of geochemical (tree bark, rock and soil) sampling on the Lennac Lake property.
Refer also to Lennac property occurrences Thezar 75 (West), Suratt (Southeast) (093L 338) and Jacob (093L 243) for related information.
