The Cirque showing area is underlain by Eocene volcaniclastics of the Sloko Group and Carboniferous volcaniclastics of the Stikine Assemblage. In the region, Sloko Group volcanics, felsite and rhyolite, overlie mixed Lower Jurassic Laberge Group sediments. Several stocks of granitic to dioritic composition intrude the volcanics and sediments in a belt subparallel to the eastern margin of the Coast Plutonic Complex.
The area of the claims is underlain by a series of cream to buff coloured rhyolitic flows of the Early Eocene Sloko Group volcanics, and by a genetically associated grey felsite and a pinkish syenitic (monzonitic?) intrusion, with a relatively wide chill margin, of the Paleocene to Eocene Sloko-Hyder Plutonic Suite. Feldspar porphyry dikes cut all rocks on the property. The felsite is microcrystalline with small phenocrysts of glassy quartz and relics of feldspars. The intrusive ranges in composition from diorite to syenite over several metres, and generally is a fine to medium-grained pink rock, frequently containing phenocrysts of glassy quartz, orthoclase, and plagioclase feldspar.
Finely disseminated euhedral pyrite is relatively consistent throughout the intrusive, and is also found in the felsite, rhyolite, and andesite. Several wide faults cross the property in two general strike directions, about 090 degrees and 045 degrees, respectively. Secondary quartz, orthoclase, and sulphides have mineralized faults trending in both directions as well as minor faults and shears which lie parallel and perpendicular.
Chalcopyrite and molybdenite mineralization occur as disseminations and fracture fillings in the secondary quartz-orthoclase veinlets in the syenitic intrusive. Minor enargite and tetrahedrite also occur within the quartz veinlets and fractures. Samples taken in 1969 returned the highest individual assay of 0.29 per cent copper over 6.1 metres (Assessment Report 2512). Drilling between 1964 and 1965 yielded values ranging from 0.1 to 0.3 per cent copper with traces of molybdenum (Assessment Report 2512).
Work History
The porphyry-style Cirque Zone, on Rimfire’s Thorn 3 and 4 claims, was discovered in 1964.
Julian Mining Co Ltd acquired the Kay group of 44 recorded claims in 1964. Work during 1964-1965 included geological mapping, geochemical, induced potential, and magnetic surveys, and diamond drilling in 6 holes totalling 827.8 metres. The best intersection graded 0.19 per cent copper and 0.07 per cent molybdenite over 10.7 metres (private report by Adamson (1965), as reported in Assessment Report 26433). The remaining zones were evaluated by hand-trenching, chip sampling, limited soil sampling and reconnaissance magnetic and induced polarization survey lines.
In 1969, American Uranium Limited carried out work on two small claim groups: the Ink, which covered the Thorn near the mouth of Camp Creek and the Lin over the Cirque Zone. On the Cirque Zone, American Uranium outlined a coincident copper-molybdenum soil geochemical anomaly over an area 500 metres in diameter (Assessment Report 2512).
Rimfire Minerals Corporation optioned the Check-mate and Stuart claims in February 2000, carried out an airborne magnetic/EM geophysical survey in July and staked the Thorn 1–7 claims in August to extend the property over the Outlaw soil geochemical anomaly and the Cirque copper porphyry prospect.
First Au Strategies Corp (Cangold Limited) optioned the Thorn property in March 2002. During 2003, Cangold conducted two stages of exploration on the Thorn property with a skeleton crew conducting mapping and prospecting near the Cirque and Outlaw zones. Two styles of mineralization were noted: porphyry-style pyrite-chalcopyrite-molybdenite in quartz veins hosted by monzonite/diorite intrusive rocks; and secondly, disseminated chalcopyrite and pyrite in subaerial volcanic rocks south of the Cirque showing.
In 2013 Brixton Metals ran a single ridge soil line where soils were collected at 100 metre stations (Figure 15, Assessment Report 34506). Soil samples were collected from the B-horizon where possible or as talus fines where poor soil development exists. A copper in soil anomaly about 600 metres in length was identified. Six samples yielded greater than 100 parts per million copper and three samples were greater than 500 parts per million with a high of 1100 parts per million copper (Assessment Report 34506).
In 2017, Brixton Metals Corporation collected a total of 517 soil samples and 56 rock samples from their Thorn Property. The majority of rock and soil samples were collected from the Chivas Zone. Samples were also collected at the Cirque and Son of Cirque zones, as well as in unexplored areas located north of the Sutlahine River, and northeast and south of the Chivas Zone. A strong arsenic anomaly associated with weak-to-moderate gold-silver in soils is reported at the Son of Cirque zone. At this location, soil assays (samples SS17-LJ301 to SS17-LJ316) ranged from 10 to 110 parts per billion gold, 0.53 to 2.78 parts per million silver and 247 parts per million to greater than 1 per cent arsenic (Assessment Report 36829). At the Cirque zone, the most significant soil sample collected (SS17-LJ052) yielded 7.8 parts per million silver and 100 parts per billion gold (Assessment Report 36829).
In 2020, Brixton Metals Corporation completed a program of geochemical (rock and soil) sampling, a 12.5 line-kilometre ground induced polarization survey, a 715 line-kilometre airborne magnetic and electromagnetic survey and 19 diamond drill holes, totalling 5292 metres, on the area of as part of the Thorn property. Drilling was performed on the Outlaw (MINFILE 104K 176) occurrence area.
Refer to Thorn (104K 031), Outlaw (104K 083) and Oban (104K 168) for details of a common work history and geological setting.
