The Theban showing is located 5.0 kilometres northwest of The Pillar and 10 kilometres due south of Toodoggone Lake (Assessment Report 2082). The showing is 280 kilometres north of Smithers.
The Theban showing is situated within a Mesozoic volcanic arc assemblage which lies along the eastern margin of the Intermontane Belt, a northwest-trending belt of Paleozoic to Tertiary sediments, volcanics and intrusions bounded to the east by the Omineca Belt and to the west and southwest by the Sustut and Bowser basins. Permian Asitka Group crystalline limestones are the oldest rocks exposed in the region. They are commonly in thrust contact with Upper Triassic Takla Group andesite flows and pyroclastic rocks. Takla volcanics have been intruded by the granodiorite to quartz monzonite Black Lake Suite of Early Jurassic age and are in turn unconformably overlain by or faulted against Lower Jurassic calcalkaline volcanics of the Toodoggone Formation, Hazelton Group.
The dominant structures in the area are steeply dipping faults which define a prominent regional northwest structural fabric trending 140 to 170 degrees. In turn, high angle, northeast-striking faults (approximately 060 degrees) appear to truncate and displace northwest-striking faults. Collectively these faults form a boundary for variably rotated and tilted blocks underlain by monoclinal strata.
The Theban showing is hosted within a northwest trending, lens-shaped intrusive complex of Early to Middle Jurassic age consisting of equigranular biotite, hornblende granodiorite to quartz monzonite and rare diorite (Bulletin 86). This intrusive complex is enveloped by volcanics of the Toodoggone Formation; the volcanics to the east are assigned predominantly to the Metsantan Member and those to the west are undivided. The intrusive phases hosting the Theban showing are equigranular and porphyritic monzonite, syenite and diorite. Numerous quartz, feldspar porphyry and trap dikes crosscut volcanics and the main intrusive phases. Within the intrusive complex, the syenite appears to be the oldest followed by diorite and finally monzonite.
The intrusive complex is conspicuously strongly fractured and permeated with disseminated pyrite. Most of the biotite and hornblende in these rocks has been altered to chlorite. Sericite and clay alteration are also evident but their distribution is erratic.
Chalcopyrite is localized in narrow, quartz-epidote stringers and hairline fractures, mainly within siliceous zones and at the contacts between intrusive phases and with tuffs of the Toodoggone Formation. The Theban showing is of the latter type. Malachite is more prevalent at the surface than chalcopyrite. Trenching and sampling was conducted over 15.25 metres at the Theban showing, yielding 0.12 per cent copper (Assessment Report 2082).
In 1996, a rock sample (LPJ-3) of propylitized monzonite hosting quartz veins with malachite and chalcopyrite assayed 0.216 per cent copper and 5.7 grams per tonne silver (Assessment Report 25054).
Other zones of mineralization, identified in 1981 and located approximately 0.7 kilometre to the south-southeast, are composed of pyritic gossans and quartz±chlorite veins with local quartz-sericite alteration hosting minor pyrite, galena and chalcopyrite.
Work History
In 1969, Cominco Ltd. completed a program of geological mapping and geochemical (rock, silt and soil) sampling on the area as the Theban claims.
In 1971 and 1972, Kennco Explorations Ltd. completed programs of geological mapping and geochemical (rock, silt and soil) sampling program on the area as the Black claims.
In 1980 and 1981, Serem Ltd. completed programs of prospecting, geological mapping and geochemical (rock, silt and soil) sampling on the area as the OJ, Orange, Arg and Argus claims.
During 1985 through 1987, Rhyolite Resources Inc. completed programs of geological mapping, trenching, geochemical (heavy mineral, rock and soil) sampling and a 200 line-kilometre airborne geophysical survey on the Adrian, Argus, Ian, Otto and Paul claims. Also in 1987, Beachview Resources Ltd. prospected and sampled (rock and soil) the area as the Brooke and Lee claims. In 1988, Rhyolite Resources completed a further program of rock and soil sampling, geological mapping and a 7.2 line-kilometre induced polarization survey on the Ian, Otto, Adrian, Paul and Argus claims. In 1990, Rhyolite conducted a soil geochemical sampling program to extend the coverage of an existing survey grid and to explore a new area within the claim group.
In 1992, Electrum Resources completed a program of heavy mineral sampling on the area as the Pil 1-3 claims. The following year, the Pil claims were expanded and a further program of prospecting and geochemical (heavy mineral, rock and silt) sampling was completed. In 1995, Electrum Resources completed a program of rock and soil sampling and a 9.7 line-kilometre ground magnetic survey on the Pil claims. In 1996, a minor prospecting and sampling program was completed along with LANDSAT TM and Radar imagery review. In 1997, a further program of rock and soil sampling and 28.7 line-kilometres of ground geophysical surveys were completed on the Pil claims. In 1998, Electrum Resource completed a program of geological mapping, geochemical (rock, silt and soil) sampling and a 4.9 line-kilometre ground magnetic survey on the Pil claims.
In 1999, Finlay Minerals purchased the Pil property and conducted a major exploration effort including induced polarization and magnetic surveys, geochemical (soil and rock) sampling and detailed geological mapping. During 2001 through 2007, Finlay Minerals completed further programs of geological mapping, geochemical sampling, trenching, diamond drilling and geophysical surveys on the Pil property. A complete summary of this work can be found in the Pil South (MINFILE 094E 310) occurrence.
In 2015, Finlay Minerals completed a program of geological mapping and geochemical (rock and soil) sampling on the Pil claims.
