The Bighorn phosphate prospect outcrops on Inverted Ridge on the south side of Bighorn Creek, 45 kilometres southeast of Fernie.
The property area is dominantly underlain by black shale of the Jurassic Fernie Group which unconformably overlies the Triassic Spray River Group comprised of indurated shale, mudstone and siltstone. The base of the Fernie Group is marked by a persistent pelletal phosphorite horizon that is 1 to 2 metres in thickness.
The area in the vicinity of Bighorn Creek near the southwest margin of the Fernie Basin is underlain by fine-grained quartzose sandstones, siltstones and dolomitic siltstones of the Permian Ranger Canyon Formation (Ishbel Group), overlain by siltstones and calcareous or dolomitic siltstones of the Triassic Sulphur Mountain Formation (Spray River Group), followed by shales, siltstones and minor sandstones of the Jurassic Fernie Group. These units are situated on the west limb of an anticline trending northwest along the east side of the MacDonald thrust fault. This stratigraphy is locally warped into a smaller anticline-syncline pair.
Phosphate mineralization is contained in the Fernie Group and the Ranger Canyon Formation. A phosphorite horizon trends northwest along the southwest side of Bighorn Creek at the base of the Fernie Group. The horizon consists of a 0.75-metre-thick layer of dense black phosphate with limonite blebs, overlain by 1.5 metres of silty shale and pelletal phosphate, which is in turn overlain by 1.5 metres of chocolate-coloured shale. A sample taken across its 2-metre thickness contained 18.50 per cent P2O5 (Open File 1987-16, Figure 33). A composite chip sample averaged over a true thickness of 0.51 metres contained 23.74 per cent P2O5 and 0.690 per cent yttrium (Assessment Report 19938, page 16, section IVR89-2).
This occurrence was first explored by First Nuclear Corporation in 1981 and then prospected by Formosa Resources Corporation in 1989.
WORK HISTORY
In 1978, Imperial Oil (ESSO) drilled thirty-three (33) holes totaling 430 metres on the Cabin 1, 2, 3 and Ram 1 and 2 claims (Assessment Report 7617). Five holes were about 50 metres in depth and 28 holes are 20 metres or less. Three showing (Cabin #1, Cabin #2, and Cabin #3 (see 082GSE055)) and 1 showing (Ram 1 (082GSE056)) on the Ram claims.
In 1981, First Nuclear commenced a program of airborne and car-borne radiometrics followed by field prospecting and caterpillar trenching to assess the surface exposure of the favourable sediments exposed along the erosional edge of the Fernie basin some 72 kilometres in length (Assessment Report 10135). A total of 18 sections were exposed through the basal portion of the Fernie Formation. The Bighorn occurrence (082GSE060) was first explored by First Nuclear Corporation in 1981 and then prospected by Formosa Resources Corporation in 1989.
In 1989, Formosa Resources Corporation began exploration for yttrium and phosphate in the area, staking several claims as part of the Columbia Project (Assessment Reports 19948, 19954, 19938). A significant section of the phosphate trend was trenched as the RAM A (082GSE063). The phosphate bed/layer was explored from Leslie Creek west to a south-flowing tributary of Bighorn Creek. A MINFILE occurrence (Ram 1 (082GSE056)) is documented up the tributary from the confluence, where the phosphate layer continues. A total of 8 hand trenches and 9 backhoe trenches revealed the phosphate layer intermittently over 5 kilometres from southeast (near Ram A) to the northwest (near Ram 1) along its trend (Figure 5, Assessment Report 19938). In 1992, Formosa Resources conducted an 8-kilometre radiometric survey over a 400 by 2000 metre grid area considered to have potential for a higher-grade phosphate mineralization (Assessment Report 22736). The west end of the grid area appears to be near to where the northeast-flowing north fork of Leslie Creek comes close (within 700 metres) of the Ram A access road, possibly between trenches 89-5 (Ram A prospect) and 89-7 (082GSE123) (Figure 5, Assessment Report 19938).
In 1996, exploration by Mammoth consisted of staking and prospecting across the 48 units over a 6-day period (Assessment Report 25076). The prospecting consisted primarily of checking locations of known outcrops and trenches from earlier mapping and prospecting programs on their Cabin Creek (082GSE055 and 082GSE068 area), Barnes Lake (082GSE051) and Hunger Lake (Ram A (082GESE063)) claims. In 1998, work by Ecomineral Resources Ltd. (and Mammoth Geological) on their Barnes Lake, Leslie Creek (Hunger Lake) and Cabin Creek properties consisted of surface sampling to obtain 5-gallon pails of phosphorite for metallurgical testing (Assessment Report 25643). Samples were obtained from the Cabin Creek and Barnes Lake properties only. In 1999, Mammoth Geological conducted exploration on their Fernie Phosphate project, consisting of 2 claims (Cabin Creek in mapsheet 082G02E and Bighorn in 082G02W) totaling 31 units. Work consisted of the collection of 1 pail near the Bighorn prospect (082GSE060) of weathered phosphorite for metallurgical and agronomical testing (Assessment Report 25989, 26033). Some work was completed on the Cabin Creek property as well (082GSE055 and 082GSE068 area).
In 2008 Paget Resources Corporation conducted a program on their Barnes Lake and Bighorn – Cabin Creek claim groups which consisted of eight reverse circulation holes totaling a total of 425 metres drilled. Seven of the holes were drilled on the Bighorn - Cabin Creek claim blocks (377 metres) and one on the Barnes Lake claim block (48 metres). Geological mapping and limited trenching were also carried out. The 2007 Fernie Phosphate exploration program failed to confirm the presence of phosphorite rock with P2O5 concentrations greater than 1.3 per cent (Assessment Report 30091).
In 2017, the program of Fertoz International Inc. consisted of reconnaissance geochemistry, rock sampling, soil sampling and establishing access. Work included locating historical phosphate workings, re-sampling several old trenches, reconnaissance mapping, prospecting and soil sampling in the Ram 1 area (082GSE056) (Assessment Report 37201). Mapping and sampling surveys conducted along the headwaters of Bighorn Creek identified a phosphate-bearing horizon that trends northwest and appears to extend up northwestern branch of the creek. Soil samples show the subcrop of the phosphate horizon. Rock samples from a large road pit/trench area at DC returned higher P2O5 values. In 2018, Fertoz International collected 11 rock samples on their Bighorn property which included the Ram 1-6, Bighorn 7 and Bighorn Southwest claims (Assessment Report 37967). The 2018 report also documents 2017 work by Fertoz. Work was done on the Bighorn (082GSE060) and Ram South (082GSE067).
Refer to Ram A (082GSE063), Ram 1 (082GSE056), and Cabin Creek (082GSE055) for related work history and geological information.
