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Coles Creek copper-molybdenum deposit, Troitsa Lake, Omineca Mining Division, British Columbia, Canadai

Regional Level Types
Coles Creek copper-molybdenum deposit	Deposit
Troitsa Lake	Lake
Omineca Mining Division	Mining Division
British Columbia	Province
Canada	Country

The Coles Creek copper-molybdenum prospect is located about 5 kilometres south-east of Troitsa Lake and 141 kilometres south of Smithers, British Columbia, in the Omineca Mining Division. Note that this is one of a group of mineral occurrences on this large property; for more information refer also to Minfile records for: FAB, etc. (093E 041); FAB 44, BRECCIA ZONE (093E 043) and FAB 45, HORNFELS ZONE (093E 044). Minerals listed herein refer to the entire system, not just the central FAB 49 copper-molybdenum occurrence.
There is a brief description of the occurrence on the British Columbia “Minfile” site, current to 2020, to which interested readers are referred. The relevant portion pertaining to the geology of the porphyry copper-molybdenum zone is presented here:
“Porphyry copper mineralization is associated with a sub-circular, porphyritic, hornblende biotite granodiorite stock of the Late Cretaceous Bulkley Plutonic Suite. The stock is primarily bounded by a dacite porphyry lacolith [sic - laccolith] and cuts Lower Jurassic Hazelton Group rocks on its western edge. Mineralization consists of chalcopyrite, pyrite and molybdenite in quartz vein stockworks and sulphide-filled micro-fractures. Pervasive biotite-orthoclase alteration is associated with this mineralization. Chalcopyrite-magnetite-biotite stringers are also present.”
MacIntyre (1985) reported that “Potassium-argon analyses of biotite from the porphyritic granodiorite stock indicate an isotopic age of 83.8 ± 2.8 Ma . . . .”
There are no recorded mineral resource estimates available for this prospect.
The Coles Creek prospect is included in the USGS compilation by Singer et al. (2008). The information given by Singer et al. (2008) is incomplete.

Giles Peatfield comments on the minerals reported:
The reported mineralogy of the Coles Creek property is relatively simple. All minerals listed, with the exception of calcite and baryte, were reported by MacIntyre (1974); only a selected number of those present deserve comment:
Amphibole group: MacIntyre (1974) listed multiple occurrences of “hornblende” but gave no more specific data.
Apatite: MacIntyre (1974) reported “apatite” in quartz diorite, but gave no more specific data.
Baryte: Lambert (1988) found that “Sulphide-bearing veins occur in the Hornfels Zone, a zone approximately 50 meters wide located on the north-western edge of the quartz-diorite dyke . . . . These veins range in width from 0.5 to 13.0 centimeters and contain quartz-galena-sphalerite-chalcopyrite-barite-tetrahedrite(?).”
Bornite: MacIntyre (1974) reported that bornite was a minor constituent of the copper mineralization.
Calcite: This was reported by Gambardella and Allan (1968), who wrote that “Carbonate alteration, as blebs and fracture filling of calcite and minor siderite is restricted to fault zones in the volcanic and sedimentary rocks, and is generally accompanied by galena and sphalerite.” MacIntyre (1985) noted that in the porphyry copper target area, “Late calcite and ankerite veinlets occur below the zone of weathering.”
Chlorite group: MacIntyre (1974, 1985) reported “chlorite” as an alteration product but gave no more specific data.
Feldspar group: MacIntyre (1974) reported orthoclase, often as an alteration product, and plagioclase as andesine.
Malachite: This mineral may be common at Coles Creek, but appears to be under reported. MacIntyre (1974) listed a very few occurrences in his tabulations of minerals present. Lambert (1988), on the other hand, reported numerous occurrences of malachite in her descriptions of rock specimens.
Mica group: Describing alteration of the granodiorite porphyry, MacIntyre (1974) wrote that “Plagioclase phenocrysts in these rocks are occupied by a fine-grained intergrowth of sericite (2M1 muscovite x-ray pattern) and quartz commonly enclosing a small solution cavity encrusted with euhedral pyrite . . . .” This explains where Singer et al. (2008) found their reference to “muscovite”. Biotite has been commonly reported; Lambert (1988) made the point that it is a defining constituent of the hornfels unit.
Tennantite: MacIntyre (1974) specifically reported tennantite, but gave no reason why he preferred this to tetrahedrite. Lambert (1988) reported tetrahedrite in two core samples, although in the text of her report she had, apparently following MacIntyre (1974), reported tennantite. Examination of her analytical data for these intervals show arsenic contents far in excess of antimony, thus suggesting tennantite rather than tetrahedrite. No other arsenic species have been reported. For the moment I am prepared to accept tennantite, but more work would be required for a definitive answer.
Tourmaline group: This was reported by MacIntyre (1974, 1985) but with no specific mineral data.
Giles Peatfield comments on the rock types reported:
The rock types listed are taken from several reports. I have chosen to comment individually on the various units.
Agglomerate: Gambardella and Allan (1968) wrote that “The Hazelton Group consists of massive, fine grained andesites, andesite breccias, rhyolite agglomerate and greywacke.”
Andesite: See note above for agglomerate. MacIntyre (1985) described “Hazelton Group andesitic fragmental rocks peripheral to the Coles Creek intrusions . . . .”
Aplite: MacIntyre (1974) wrote that “Aplite dykelets, up to 4 inches wide, cut granodiorite porphyry and quartz diorite.”
Breccia: See comment above for agglomerate. MacIntyre (1974) wrote that “The breccia of the Breccia Zone post dates intrusion of quartz diorite and formation of biotite hornfels but predates formation of magnetite veinlets. This suggests brecciation occurred during the early stages of minor hydrothermal activity which followed consolidation of the [quartz diorite] dyke.”
Conglomerate: MacIntyre (1985) wrote that “Lapilli tuff, pebble conglomerate, and volcanic sandstone beds of the lower part of the Kasalka Group are preserved within a graben south of the [porphyritic hornblende-biotite granodiorite] stock; . . . .”
Chert: Lambert (1988) mentioned that “Telkwa Formation rocks [of the Hazelton Group] form the bulk of exposures on the property and are represented by lapilli and crystal tuffs, andesite flows and black siltstone/argillite with minor interbeds of volcanic breccia, chert, volcanic sandstone and pebble conglomerate (Awmack, 1987; MacIntyre, 1974).” Note that later, MacIntyre (1985) placed these strata within the younger Kasalka Group package.
Dacite: MacIntyre (1974), describing the Coles Creek prospect area, wrote that the host granodiorite porphyry stock “. . . intrudes a subvolcanic laccolith of dacite porphyry. The latter is emplaced along the interface between a comagmatic volcanic pile and Middle Jurassic basement rocks of the Hazelton Group.”
Granodiorite: MacIntyre (1985) wrote that “The Coles Creek property . . . has porphyry copper-type mineralization associated with a single phase, subcircular porphyritic hornblende-biotite granodiorite stock . . . .”
Greywacke: This was reported by Gambardella and Allan (1968); see note above for agglomerate. Note that the name greywacke was used by many workers of the era in this area. It may be that this is the same as the sandstone reported by MacIntyre (1985) and Lambert (1988); see note below for sandstone.
Hornfels: See comment above for breccia.
Quartz diorite: MacIntyre (1974) described the “Quartz Diorite Dyke” as “Medium-grained equigranular, leucocratic biotite-quartz diorite.”
Sandstone: See note above for greywacke.
Tuff: See note above for conglomerate.

Giles Peatfield
BASc. (Geological Engineering) University of British Columbia 1966.
PhD Queen's University at Kingston 1978.
Worked for Texas Gulf Sulphur / Texasgulf Inc. / Kidd Creek Mines - 1966 to 1985.
Vancouver based consultant 1985 to retirement in 2016

Other Databases

Link to British Columbia Minfile:	093E 042

Other Regions, Features and Areas containing this locality

References

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