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File Created: 18-Apr-2021 by Garry J. Payie (GJP)
Last Edit:  27-Jun-2023 by Garry J. Payie (GJP)

Summary Help Help

NMI
Name GOSSAN BEAR, CHACO BEAR, GOSSAN ZONE, GOSSON ZONE Mining Division Omineca
BCGS Map 094D016
Status Showing NTS Map 094D02W
Latitude 056º 07' 48'' UTM 09 (NAD 83)
Longitude 126º 55' 53'' Northing 6222475
Easting 628565
Commodities Gold, Silver, Copper, Molybdenum Deposit Types L04 : Porphyry Cu +/- Mo +/- Au
Tectonic Belt Intermontane Terrane Stikine
Capsule Geology

The Gossan Bear area is underlain by Lower Jurassic Telkwa Formation (Hazelton Group) volcanics. Minor porphyritic (plagioclase and/or hornblende) flows and interflow sedimentary rocks are also present. The volcanic rocks are intruded by narrow quartz feldspar porphyry dikes which are 1 to 3 metres wide and strike northeast. The dikes, fine to medium-grained, are probably related to the Eocene Kastberg Intrusions.

This Gossan Bear occurrence is located along the west ridge and is manifested as three prominent limonite altered gossan knobs aligned in a northwest orientation over a length of approximately 1.3 kilometres. The most obvious gossan is located along the southwest portion of the ridge with the intensity of alteration gradually decreasing to the south. This area has a very complex geology due to the presence of 50 per cent mafic and felsic dikes crosscutting andesitic flows and tuffs. Local intrusive pink leucogranite to leuco-syenite dikes are present near the top of the west ridge. Mafic dikes are more variable in nature, ranging from fine grained to aphanitic medium green coloured magnetic units, to coarser grained diorite/gabbro, to feldspar porphyritic, cumulate textured, both also magnetic. The northwest orientation is most common with moderately steep dips to the southwest.

In 1997, Imperial Metals collected several grab and chip samples from this zone with variable results obtained. None of the grab samples returned any highly anomalous results from the gossans themselves but elevated results were received from samples on top of the west ridge and on its west side. The chip samples were equally disappointing with six chip lines completed over the zone. Three of these lines, chip lines # 1 to 3 were completed on the southernmost gossan, none of which returned anomalous values.

Only chip line #1 covered pink leuco-granite to leuco-syenite dike (possible related to Kastberg intrusions) yielded elevated molybdenum values in the range of 3-23 ppm molybdenite. This was also the only area sampled within the claim group to yield any elevated molybdenum values except for isolated values from the Coccola Zone. Chip lines #4 and 5 were completed over the middle gossan and returned somewhat better results. Elevated gold ranging from 0.095 -0.6 gram per tonne gold was obtained from four contiguous samples over 6.0 metres on chip line #4 with a high of 5.7 grams per tonne silver along with the highest gold assay. Higher gold values were obtained on chip line #5, up to 3.1 gram per tonne gold over 2.0 metres, with three other anomalous values ranging from 0.659-1.61 grams per tonne. Copper values are all less than 100 ppm with two exceptions where assays of 512 ppm copper and 623 ppm copper were obtained, both over 2.0 metres, from non-contiguous samples. (Figure 20, Assessment Report 25270). The final chip line, #6, was completed over a zone of limonite-stained rock in a tributary of the Driftwood River that delimits the northern boundary of the Ferruginate Zone. No significant values were received from this line.

In 1997, four target areas were tested by diamond drilling program conducted by Imperial Metals; the Beamx, Dave/Ron, Coccola, and Gosson zones. The Gossan Bear zone is a large area of extensive pyritization of andesite flows and lesser tuffs cut by andesite dikes. Hole CB-97-16, as shown on the Grid Map, fig. 6, attempted to drill through this ‘pyritic halo’ to test for possible “porphyry-style” mineralization at depth (Assessment Report 25270). This hole was lost in blocky ground at 117.96 meters failing to reach the targeted depth of 260 metres. Hole CB-97-16 intersected massive, plagioclase phyric, andesite flows. These were variably epidote-altered and overprinted by chlorite-carbonate alteration. Amygdaloidal, magnetic, andesite dikes cut the flows. Both the flows and the dikes are uniformly pyritized with fine pyrite content less than or equal to 1 per cent. Pyrite is locally concentrated on fracture surfaces. Narrow veins of specularite were encountered in the first 50 metres of the hole but without any accompanying sulphide minerals, except for one speck of chalcopyrite observed at 52.63 metres. No significant assays were returned.

See Bearnx (094D 003) for related details mainly work history for years 1996 and 1997.

Bibliography
36041, 38636
EMPR EXPL 1986-C380, C381
EMPR PF (In 094D General File - Canadian Superior Exploration Limited,
Maps from Company Files, c. 1973)
GSC OF 342
GSC P 76-29
GSC MEM 251, p. 62
GSC MAP 962A
GCNL #74, 1964
Placer Dome File

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