Banks Island lies along the western edge of the Tertiary- Jurassic Coast Plutonic Complex characterized by northwest trending granitic bodies, mainly granodiorite-quartz monzonite and quartz diorite which are separated by narrow, persistent Permian(?) or older metasedimentary belts, mainly crystalline limestone, micaceous quartzite skarn and schist. The metasedimentary rocks generally exhibit a wide range of "granitization" effects and contact metasomatism.
Regional and local faulting, fracturing and folding are common on the Island. Two major right-lateral faults, striking 310 degrees, known as the Arseno and Hepler faults, have associated 045 degree linears. Left-lateral faults striking 090 degrees also occur. Many contacts between the plutonic and metasedimentary rocks are faults or drag folds. Some faults have been healed by recrystallization. Structure is the prime factor in ore localization.
The Yellow Giant (Bob) deposit occurs near the intersection of the northwest trending Bank-Barge lineament and the east trending Survey Bay fault, at the north end of the "Western Metasedimentary Belt". Underlying the deposit is an unusual biotite quartz diorite breccia containing abundant small to very large marble and greywacke fragments.
A marble block or horst associated with high grade gold mineralization averages 12 metres wide and may be related to disrupted drag folding. Skarn development is common along margins of the marble and quartz lenses occur at the outermost phase.
The fault-controlled deposit occurs partially in calcareous pelites, marble and skarn in the upper levels and predominantly in altered quartz diorite in the lower level. The main ore shoot is a sulphide lens over 44 metres long, up to 125 metres in vertical depth, and 1.7 metre average width that dips steeply (75-80 degrees) north and strikes easterly. Subsidiary mineralization lies above (5-10 metres) and below the main deposit.
Mineralization, consisting of abundant auriferous pyrite with lesser chalcopyrite and minor sphalerite, galena, and arsenopyrite, is controlled by the Bob fault, a well-defined steep north dipping, east-northeast striking fault which cuts all rocks and is accompanied by zones of intense brecciation.
Sampling of an underground drift, 40 metres below surface, averaged 31.71 grams per tonne gold and 97.03 grams per tonne silver across 1.69 metres along a 44 metre length. A drill hole intersected 46.63 grams per tonne gold and 168.17 grams per tonne silver over 4.5 metres in a massive pyrite and chalcopyrite zone (Assessment Report 14171).
Additional surface showings occur near the Bob zone. Showing A20, 70 metres north of the Bob deposit, occurs near the West Bank fault within skarnified marble adjacent to diorite.
Another skarn-associated showing, 240 metres southeast of the main zone, contains pyrite and arsenopyrite and assayed 710 grams per tonne gold in a rock chip sample (Assessment Report 14171).
The Bob zone was discovered in 1963 by Falconbridge Nickel Mines Ltd.
In 1964, Falconbridge Nickel Mines Ltd. conducted geological surveys, geophysical surveys, mapping and packsack drilling on the Bob zone and found anomalous gold values in the drillholes.
In 1976, Falconbridge Nickel Mines Ltd. completed 1130.2 metres of diamond drilling on the Yellow Giant property with 427 metres focused on the Bob zone. Anomalous gold values were found in the drillholes.
In 1977, Hecate Gold Corp. entered an option with Falconbridge Nickel Mines Ltd. and completed the excavation of a 420 metre decline along the major vein and 100 metres of underground drilling.
In 1984, Trader Mines Ltd. completed trenching, geological mapping, soil sampling and diamond drilling. Drilling intersected a zone of sphalerite and galena assaying 1.7 grams per tonne gold, 30.9 grams per tonne silver, 4.68 per cent zinc and 1.84 per cent lead over 0.46 metres (Assessment Report 14171). Sampling of an underground drift, 40 metres below surface, averaged 31.71 grams per tonne gold and 97.03 grams per tonne silver across 1.69 metres along a 44 metre length. A drillhole intersected 46.63 grams per tonne gold and 168.17 grams per tonne silver over 4.5 metres in a massive pyrite and chalcopyrite zone (Assessment Report 14171).
In 1988, indicated reserves for the Bob zone are 45 350 tonnes grading 40.1 grams per tonne gold (MDAP - Prospectus, Trader Resource Corporation, Yellow Giant, 1986).
In 1993, Trader Resources Corp. owned 90 per cent of the Yellow Giant property claims, while Falconbridge Nickel Mines Ltd. owned the remaining 10 per cent of the claims.
In 1994, Trader Resources Corp. was renamed Highwood Resources Ltd.
In 1996, Energex Minerals Ltd. acquired 51 per cent of the claims from Highwood Resources Ltd.
In 1998, Doublestar Resources Ltd. acquired the 51 per cent share held by Energex Minerals Ltd.
In 2000, Doublestar Resources Ltd. acquired Falconbridge Nickel Mines Ltd.’s 10 per cent stake of the claims.
In 2002, Dynatec Corp. merged with Highwood Resources Ltd. to form Beta Minerals Inc.
In 2007, Selkirk Metals Corp. acquired 61 per cent of the Yellow Giant property claims through the purchase of Doublestar Resources Ltd.
In 2009, Advanced Primary Minerals Corp. acquired 39 per cent of the claims through the reverse takeover of Beta Minerals Inc. and then sold the stake to Selkirk Metals Corp. which gave them 100 per cent ownership of the property. Imperial Metals Corp. then acquired all the shares of Selkirk Metals Corp., making it a wholly-owned subsidiary of Imperial Metals Corp.
No exploration work was completed on the property from 1988 until 2010, when Selkirk Metals Corp. completed a control survey to establish UTM coordinates for old drillholes and facilities.
In 2011, Banks Island Gold Ltd. optioned the property from Selkirk Metals Corp.
In 2012, Banks Island Gold Ltd. completed nine diamond drillholes in the Bob zone. Highlights include drillhole BOB-12-07, which returned 6.4 metres (estimated true width of 5.0 metres) grading 41.5 grams per tonne gold, 126 grams per tonne silver, 1.4 per cent copper, 0.4 per cent lead and 1.9 per cent zinc (Press Release, Banks Island Gold Ltd., May 15, 2012). Banks Island Gold Ltd. released a NI 43-101 compliant mineral resources estimate for the Bob zone that showed a measured resource of 6000 tonnes grading 32.0 grams per tonne gold and 63 grams per tonnes silver, an indicated resource of 11 000 tonnes grading 30.9 grams per tonne gold and 58 grams per tonne silver and an inferred resource of 8000 tonnes grading 29.3 grams per tonne gold and 50 grams per tonne silver using a 6 gram per tonne gold cut off (Press Release, Banks Island Gold Ltd., October 22, 2012).
See Kim (103G 021), Discovery (103G 025) and Tel (103G 026) showings for additional information and resource estimates.