The Thelma (L.4510) occurrence is located in the northwest corner of the Thelma (L.4510) Crown grant, approximately 700 metres west of the south end of Shuta Lake.
The area around Swakum Mountain is underlain by folded Upper Triassic Nicola Group volcanic rocks with interbedded sedimentary units. These rocks are intruded by large north-trending felsic to intermediate intrusions (batholiths) east and west of the mountain. Nicola Group rocks on the mountain strike north to northeast with generally steep dips. For a large part they consist of andesitic flows and tuffs, agglomerates, and occasional basalts and rhyolites. A break occurs in the volcanic stratigraphy and is comprised of a mixed volcanic-sedimentary unit consisting of a thick sequence of felsic volcanic flows, lithic and crystal tuffs, limy sediments and a prominent limestone. This unit has a northeast strike and crosses the mountain for a 2.5-kilometre strike length. The unit has been historically used as a marker horizon in interpreting a large, asymmetrical, south plunging anticline with its north trending axis near Swakum Mountain summit. Narrow quartz porphyry dikes locally intrude the Nicola Group sequence. To the east of this marker unit are a thick, unconformable wedge of immature sediments, predominantly coarse polymictic conglomerates (fan-type) and grits with minor cherty units. Most of the old workings on the mountain occur in close proximity to or within this volcanic-sedimentary unit and consist of polymetallic skarn-type mineralization, lead-zinc-silver–bearing quartz veins and replacements, and polymetallic quartz veins.
The occurrence area covers the contact zone between the volcanic and sedimentary sequences of the Upper Triassic Nicola Group. Limestone and conglomerate beds strike north and dip steeply to the east. At the 1615 metre elevation, a 30-metre wide band of dark-grey limestone is exposed for 106 metres in a northerly direction. The limestone is massive and contains scattered thin stringers of white calcite, some chert nodules and vague shapes that may be fossils. A sample taken across 30 metres at the centre of the exposure yielded 0.28 per cent iron (III) oxide, 0.07 per cent manganese (II) oxide, 0.44 per cent magnesium oxide, 51.22 per cent calcium oxide, 0.026 per cent phosphorus pentoxide, 0.03 per cent sulphur, 40.8 per cent Ig. Loss , 0.04 per cent water, 7.08 per cent Insol. and 0.46 per cent R2O3 (Minister of Mines Annual Report 1958).
Locally, silver-lead-zinc mineralization is exposed in tabular and lenticular garnet-epidote skarn zones up to 5 metres wide within the limestone. Pyrite, galena and sphalerite, with gold and silver values, occur as metasomatic replacements along bedding planes and as disseminations throughout the limestone. Minor copper values are also associated with the skarn. Quartz veins 10 to 15 centimetres wide are hosted by Nicola Group andesitic rocks near the volcanic-sedimentary contact. These veins carry galena and sphalerite with minor gold and silver values.
By 1938, production records indicated a total of 81 tonnes of ore was shipped yielding 31 grams of gold, 235.8 kilograms of silver, 5462 kilograms of zinc and 4632 kilograms of lead.
Work History
The Thelma occurrence consists of a shaft driven for 66 metres at an incline of 80 degrees east, underground workings and numerous surface trenches. An adit is reported approximately 45 metres north of the shaft. All of the workings are reported to have collapsed and/or filled in since work ceased in 1940.
In 1972 and 1973, Hesca Development Corp. Ltd. completed a program of rock, silt and soil sampling on the area immediately east of the occurrence as the Kay and Lyn claims of the Swakum Mountain property.
In 1979, the area was prospected by L. Trenholme as the Dartt 1-2 claims.
In 1981, S. Kelly completed a soil sampling program on the area immediately northwest of the occurrence as the Old Complex claims. In 1983 and 1984, Pacific Northwest Geotech Ltd. completed soil sampling programs on the area. Also in 1984, Mag-Ty Resources Ltd. prospected the area. In 1986, Atlar Resources Ltd. completed a program of geological mapping, geochemical (rock and soil) sampling and ground magnetic and electromagnetic surveys on the area as the Corona-Bob property.
In 1998, Ahura Mining Ltd. prospected and sampled the area as the How 1-10 and Corona claims. A rock sample (HOW-6) from the occurrence area yielded 250 grams per tonne silver and 2.30 per cent zinc (Assessment Report 25744). The following year, a program of geological mapping, rock sampling and a 27.2 line-kilometre ground electromagnetic survey was completed on the claims. A rock sample (L990703), taken near Shuta Creek and approximately 900 metres south of the shaft, yielded 0.36 per cent copper (Assessment Report 26068). In 2000, Ahura Mining completed a program of geological mapping and geochemical (rock and soil) sampling on the How property.
During 2011 through 2016, Plate Resources Corp. completed programs of geological mapping, geochemical (rock and soil) sampling, airborne and ground geophysical surveys and diamond drilling on the area as apart of the Lucky Mike property.
