The Mustang occurrence is located near Cook Lake, approximately 86 kilometres north of the community of Dease Lake.
In the Mustang occurrence area, the Upper Paleozoic Sylvester Allochthon consists of at least two individual thrust sheets thrust over Upper Devonian to Lower Mississippian Earn Group clastic rocks. The occurrence is underlain by rocks representing the ower stratigraphic section of the lower thrust sheet consisting of argillite and andesite.
Mississippian Slide Mountain Complex andesites and cherty andesites exhibit low-grade greenschist metamorphism changing the andesites to greenstones. Disseminated fine pyrite and arsenopyrite are common. Near a fault structure, the pyrite and arsenopyrite increases, and silicification and hydrothermal alteration consisting of quartz-carbonate-tremolite is intense. Carbonate veins (dolomite), up to 4 centimetres wide, were found along fault planes associated with fault gouge. Gouge zones observed are up to 1 metre wide. These alteration zones are anomalous in gold and arsenic and show spot anomalies in copper and zinc.
Trenching has traced the mineralization along strike, but diamond drilling indicates that the alteration-fault zone stops against a lower thrust and does not cut Earn Group sediments. Thin sections and polished sections cut from drillcore show evidence of epigenetic and remobilized pyrite, chalcopyrite and sphalerite.
Highly anomalous concentrations of gold, arsenic, zinc and copper are present in the hydrothermal system sampled. Alteration zones associated with north-trending faults are strongly anomalous in gold, arsenopyrite, and show spotty highs in zinc, copper and lead. Highest values from trench rock samples were up to 1.69 grams per tonne gold, 18.0 grams per tonne silver, 1.49 per cent zinc and 0.16 per cent copper, whereas diamond drilling yielded intercepts of up to 1.15 grams per tonne gold over 5.9 metres in hole 88-2 (Assessment Report 18787).
At the original Jackpine showing, blebs of sphalerite and 1- to 2-millimetre veinlets of ‘white zinc’ occur in a brecciated dolomite horizon in shale and argillite. A chip sample assayed 4.20 per cent zinc, 0.06 per cent cadmium and 1.71 grams per tonne silver (Gulf Titanium Ltd., June, 1981).
Work History
In 1987, initial exploration consisting of prospecting and regional soil sampling outlined several spot gold anomalies, which were followed up by detailed gridding and trenching. In 1988, Duke Minerals Ltd. completed percussion drilling (four holes, unknown metreage), additional trenching (nine trenches) and fill-in soil sampling (121 samples) followed by geological mapping and diamond drilling (four holes totalling 380.1 metres).
In 1996, Cartaway Resources Corp. completed a 3678.0 line-kilometre airborne magnetic survey on the area as the Hot Tip property.
During 2008 through 2010, Hawthorne Gold Corp., later China Minerals Mining Corp., completed regional programs of geological mapping, geochemical (rock and soil) sampling and 11,657 line-kilometres of airborne magnetic, radiometric and electromagnetic surveys on the area as the Cassiar Gold property.
Also in 2008, Lomiko Metals Inc. completed a helicopter-borne magnetic gradiometer and VLF-EM survey, totalling 327 line-kilometres, on the area immediately north of the occurrences as the Vines Lake property. In 2011 and 2012, Lomiko Metals Inc. conducted exploration programs on the Vines Lake property comprising prospecting, geological mapping and geochemical (rock and soil) sampling.
In 2019, Margaux Resources completed a program of prospecting, geological mapping and rock sampling on the area as the Cassiar Gold property. In 2020, Cassiar Gold Corp. completed a program of regional photogeological interpretation, prospecting and rock sampling on the Cassiar Gold property.
