The Sofia showing is located on the south bank of the Toodoggone River, approximately 2.5 kilometres northwest of the confluence of Jock Creek and Toodoggone River.
Regionally, the area 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 Paleogene 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 Stuhini Group andesite flows and pyroclastic rocks, and marine sedimentary and volcanic rocks of the Lower to Middle Jurassic Hazelton Group. These rocks have been intruded by plutons and other bodies of the mainly granodiorite to quartz monzonite Early Jurassic Black Lake Suite and are in turn unconformably overlain by or faulted against Lower Jurassic calc-alkaline volcanics of the Toodoggone Formation (Hazelton Group).
The dominant structures in the area are steeply dipping faults that 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.
Locally, a porphyry occurrence is hosted within a magnetite-bearing monzonite phase of the Early Jurassic Black Lake Plutonic Suite, which is overlain by a secondary biotite-altered mafic volcanic. The occurrence is exposed over a 40- by 10-metre area and is characterized by strong, pervasive, fracture-controlled potassic alteration. The intrusion is cut by three directions of sheeted- and stockwork-style, quartz-magnetite-chalcopyrite-pyrite-sericite–bearing veins and veinlets ranging from 0.1 to 10 centimetres and spaced 20 to 50 centimetres apart . The quartz and magnetite veins also cut the overlying Upper Triassic Stuhini Group aphyric andesitic volcanics. The latest set is a fine-quartz stockwork of 1-millimetre wide veinlets . Pyrite is common, up to 10 per cent, and associated with weak shearing and moderate sericite development.
In 2004, grab samples were reported to have assayed up to 0.22 gram per tonne gold and up to 0.05 per cent copper (Press Release, Stealth Minerals Ltd., July 16, 2004). Later that year, two chip samples (204825 and 204833) yielded 0.30 and 0.41 gram per tonne gold with 0.123 and 0.118 per cent copper over 1.00 metre, respectively, from a zone that averaged 0.14 gram per tonne gold and 0.063 per cent copper over 26.5 metres (Assessment Report 27790). Also at this time, a sample (185182), taken up slope to the northeast of the previous sample, assayed 0.121 per cent copper and 119.9 grams per tonne silver (Assessment Report 27790).
In 2007, the occurrence was tested to a depth of 318.3 metres in drillhole BCG-07-01. Chalcopyrite was observed to occur as 0.5- to 1-centimetre banded quartz-magnetite veins and along epidote- and carbonate-filled fractures. Up to 8 per cent pyrite exists throughout the hole. Drilling yielded intercepts of porphyry mineralization yielding 0.16 gram per tonne gold and 0.22 per cent copper over 10.0 metres, including 0.27 gram per tonne gold and 0.5 per cent copper over 2.0 metres and 0.08 gram per tonne gold with 0.13 per cent copper over 47.0 metres (Assessment Report 30339). To the southwest, another drillhole (BCG-07-02) yielded intercepts of 0.06 and 0.15 gram per tonne gold with 0.16 and 0.11 per cent copper over 2.0 and 4.0 metres, respectively (Assessment Report 30339).
Work History
The Sofia occurrence was discovered in August 2004 by Stealth Minerals prospectors on the western shore of the Toodoggone River.
In 1999, Stealth Minerals staked the initial claims in the area of what is now known as the Sickle-Sofia property and, later that year, Standard Metals conducted a small-scale geochemical program on the area on behalf of Stealth Minerals.
In 2003, Stealth Minerals completed a program of rock, silt and soil sampling and 78.4 line-kilometres of ground geophysical surveys on the Pine property. Also at this time, as part of a private-public partnership with the Geological Survey of Canada and the British Columbia Department of Mines and Energy, the Sickle-Sofia property was included in a multi-parameter helicopter-borne geophysical survey over the Toodoggone district. Several high potassium anomalies and low thorium-potassium ratio anomalies were detected.
In 2004, Stealth Minerals expanded the property package by staking additional claims. A grid-based soil survey was conducted over 27 square kilometres, outlining the Alexandra (MINFILE 094E 245) copper-gold soil anomaly. Concurrent prospecting identified the Sofia porphyry outcrop, the North Vein (MINFILE 094E 304) outcrop, and high-sulphidation silica-alunite alteration. A total of 728 rock and 2103 soil samples were collected.
In 2005, a program of geological mapping and a 21 line-kilometre induced polarization and ground magnetic geophysical survey was completed over the lower, glacial-fluvial–covered portion of the Sofia copper-gold porphyry target. This survey outlined an 800-metre wide by 1200-metre long, +40 millisecond induced polarization chargeability anomaly that was open to the north.
In 2006, Stealth Minerals further expanded the IP/ground magnetic survey by another 21 line-kilometres and expanded the chargeability anomaly a further 600 metres north and 300 metres west. During the 2006 season, a total of 28 rock samples were taken from outcrop and float. Geophysical surveys were completed in the area between and covering the Sofia (MINFILE 094E 238) to Quartz Lake (MINFILE 094E 301) occurrences.
In 2007, BCGold Corporation and Stealth Minerals completed four diamond drill holes, totalling 1255.4 metres, on the Sofia area.
In 2015, a program of geophysical review completed for Cazador Resources Ltd. on the Sofia property identified five target areas. Later that year, a 4.0 line-kilometre induced polarization survey was completed.
In 2017, Cazador Resources completed 239.0 line-kilometres of airborne magnetic surveying and a 2.5 line-kilometre ground induced polarization survey on the Sofia property.
Please see Sickle Creek (MINFILE 094E 237) for further details of the Stealth Minerals Limited property.
