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File Created: 24-Jul-85 by BC Geological Survey (BCGS)
Last Edit:  09-May-13 by George Owsiacki(GO)

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NMI 104I1 Cu2
Name KUTCHO CREEK, SMRB, JEFF, KUTCHO, SUMAC, ESSO WEST Mining Division Liard
BCGS Map 104I029
Status Developed Prospect NTS Map 104I01W
Latitude 58º 12' 19" N UTM 09 (NAD 83)
Longitude 128º 21' 36" W Northing 6451743
Easting 537613
Commodities Copper, Zinc, Silver, Gold, Lead Deposit Types G06 : Noranda/Kuroko massive sulphide Cu-Pb-Zn
Tectonic Belt Intermontane Terrane Cache Creek
Capsule Geology

The Kutcho Creek deposit is located around Sumac Creek, 7 kilometres east of Kutcho Creek and 100 kilometres southeast of Dease Lake.

The deposits are in the Kutcho Formation of the Upper Permian-Lower Triassic Cache Creek Complex (Geological Survey of Canada Paper 86-16) which underlies carbonates and sedimentary rocks interpreted to correlate with the Upper Triassic Sinwa Formation limestone and the Lower Jurassic Inklin Formation, respectively. The Kutcho deposits occur within the upper felsic, largely fragmental volcanic cycle of the Kutcho Formation. New dating by the Mineral Deposits Research Unit (MDRU) at the University of British Columbia yielded ages of 242 to 245 Ma for the hostrocks (F. Child, personal communication, 1995). The Kutcho Formation was previously thought to be Upper Triassic (Geological Survey of Canada Open File 2779) but this new dating places the age at the Permian-Triassic boundary. The Sinwa Formation has recently been reassigned to the Stuhini Group (Stikine Terrane), and the Inklin Formation to the Laberge Group (Overlap Assemblage) (M. Mihalynuk, personal communication, 1996). The area of the deposit is interpreted to have been isoclinally folded during formation of the King Salmon allochthon in Early to Middle Jurassic time.

The interpreted stratigraphic sequence consists of a 2000 metres or more lower unit dominated by mafic flows and tuffs with local dacite to rhyolite flows and tuffs and argillite layers. This sequence is cut by an elongated body of trondhjemite that is quartz rich and perhaps the source of the quartz crystals in the fragmental volcanic rocks that occur higher in the section. Above is the footwall unit, some 300 metres of largely lapilli tuff. The massive sulphide lenses occur where this unit gives way to lapilli crystal tuff and laterally correlative quartz-feldspar crystal tuff that are interlayered with or cut by mafic plagioclase porphyry (locally called gabbro). Above the hangingwall unit is a series of tuffs and argillites that are cut by mafic sills, then a volcanic conglomerate unit that underlies the apparent Sinwa carbonates and Inklin sediments.

The Kutcho assemblage consists of bimodal, calcalkaline basaltic andesite or basalt and rhyodacite or rhyolite. It is generally in fault contact with rocks of the Carboniferous-Jurassic Cache Creek Complex, but may have a Cache Creek basement. The assemblage occurs within the fault-bounded King Salmon allochthon. Movement on the faults was probably Early to Middle Jurassic, but uplift continued into the Late Jurassic. Rocks within the allochthon were regionally metamorphosed to greenschist facies, and deformed at that time. The sequence is interpreted to be folded, and small-scale reverse faults are common in the underground workings.

In the hangingwall of the mineralized zone, shoshonitic mafic plagioclase porphyry cuts the country rock. The porphyry locally exhibits peperite structures with sedimentary units in the Kutcho assemblage (J. Thompson, personal communication, 1995), so is apparently very close in age (syn-mineral?). The porphyry is extensively altered to chlorite and epidote. Bridge et al. concluded that the massive sulphide deposits occur at a facies change from quartz feldspar crystal tuff to lapilli crystal tuff (CIM Special Volume 37 (1986)).

Schistose quartz-eye feldspar-grain rock with scattered pyrite cubes is the dominant hangingwall lithology. The unit contains scattered clasts on the ridge above the exploration adit but is clearly fragmental with small to large lapilli to blocks of quartz feldspar porphyry, fine grained to quartz porphyritic partially flatted pumice fragments and some more exotic, calcareous, mafic-looking clasts. Geochemistry by MDRU shows this unit to be a primitive, tholeiitic rhyolite with SiO2 near 70 per cent. It is Na2O-rich and has relatively low values in zirconium, yttrium and uranium (like rhyolites in Iceland).

In the footwall sequence, on Imperial Ridge, above the adit, a foliated quartz feldspar-bearing zone underlies the massive sulphide zone. Quartz tends to be finer grained than in the hangingwall. Deeper in the footwall, variably altered feldspar phyric rocks dominate but zones with coarse quartz eyes occur locally. Below the footwall alteration is a monotonous assemblage of these rocks, then a zone with occasional thin layers of pale green to white, very fine dust to fine crystal tuffs with sericite partings. A small lens of impure marble had minor associated pyrite and chalcopyrite mineralization. The sequence is interpreted to consist largely of crystal to lapilli tuffs, and the correlative, less altered rocks on Sumac Ridge to the west are clearly fragmental volcanic rocks. On Sumac Ridge, the footwall sequence has many more coarse quartz-rich zones. The quartz and feldspar-dominated sequences are gradational over hundreds of metres of section. The feldspar-dominated section on Sumac Ridge is underlain by chlorite schists, interpreted to be derived from basalt, with local fine grained sedimentary layers. Geochemistry by MDRU indicates that the basalts are tholeiitic.

The trondhjemite is locally brecciated and foliated at its margins. In the west, it consists of medium-grained quartz, plagioclase and chloritized mafics. In the southeast, it is coarse grained and porphyritic with quartz grains to 1 centimetre in size. The coarser variety is more calcic, akin to tonalite rather than the more sodic trondhjemite (Fieldwork 1977).

In the mineralized interval on surface, the hostrock is strongly altered sericite schist with pyrite cubes and dolomite grains but no obvious mineralization. Locally, quartz eyes are still visible and fragments are seen locally in drill core. The mineralized zone has an altered footwall sequence some 300 metres thick, and a less intense, thinner zone above. Geochemically, sodium is depleted and potassium is enriched near the mineral lenses. In the footwall, this alteration extends for about 500 metres laterally and nearly 300 metres below the lenses; in the hangingwall, it extends 100 metres laterally and about 180 metres above the mineralized lenses. In the alteration halo, calcium and magnesium are also enriched and silica values are relatively elevated. The footwall zone is pyritic, both as stringers and disseminations, and has abundant disseminated dolomite. Individual deposits are stratabound and lenticular; they pinch out to the south updip but interdigitate with the country rock downdip to the north. All are at the same relative stratigraphic position but individual lenses are en echelon and separated by about 300 metres. They strike about 280 degrees and dip north at 40 to 45 degrees (CIM Special Volume 37 (1986)).

Mineralization occurs in three areas along 3.5 kilometres (CIM Special Volume 37, 1986) of a zone that extends for about 15 kilometres (Fieldwork 1975). Intense footwall alteration and a footwall pyrite zone are developed throughout the zone. Metallic minerals occur in a series of massive sulphide layers and include pyrite, sphalerite, chalcopyrite, bornite, minor chalcocite, trace tennantite, galena, digenite, djurleite and idaite. Schistose partings occur locally in the massive sulphide zone exposed in the adit. Whether this represents pulses of mineralization or structural repetition is not clear. Metal zoning occurs laterally in the ore lenses with copper-rich cores and zinc-rich peripheries but is not evident vertically within the lenses. Non-sulphide gangue includes dolomite, quartz and sericite.

Reserves for the three zones are: Kutcho - 17 million tonnes grading 1.62 per cent copper, 2.32 per cent zinc, 29.2 grams per tonne silver and 0.39 gram per tonne gold; Sumac - approximately 10 million tonnes grading 1.0 per cent copper and 1.2 per cent zinc; and Esso West - about 1 to 1.5 million tonnes of approximately double Kutcho grades (CIM Special Volume 37 (1986), page 122).

An "underground mineable reserve" was reported in 1991 for the Kutcho lens as 11.6 million tonnes grading 1.67 per cent copper, 2.30 per cent zinc, 32.7 grams per tonne silver and 0.36 gram per tonne gold; and for the Esso West lens as 2.7 million tonnes grading 2.14 per cent copper, 3.61 per cent zinc, 44.9 grams per tonne silver and 0.40 gram per tonne gold (George Cross News Letter No.54 (March 18) 1991).

Mineable reserves of the Kutcho lens is also reported as containing 14.3 million tonnes grading 1.76 per cent copper, 2.54 per cent zinc, 35 grams per tonne silver and 0.37 grams per tonne gold (Exploration in British Columbia 1996, page B12).

Late in 2003, Western Keltic Mines Inc announced its pending acquisition of the Kutcho Creek property. In 2004, work by Western Keltic comprised 21 large diameter (HQ) holes totalling 2166 metres at the Kutcho deposit that improved definition of higher grade areas, slightly extended limits of the deposit and extracted a sample for metallurgical study. Eight holes (625 metres of NQ) also tested the Footwall zone adjacent to the Kutcho deposit. The best overall intercept was near the margin of the Kutcho lens and yielded 8.3 metres grading 5.34 per cent copper, 5.94 per cent zinc, 138 grams per tonne silver, 2.28 grams per tonne gold (Exploration and Mining in British Columbia 2004, page 26). Work in the Esso West lens comprised 12 drillholes that expanded the deposit. Hole 04-27b1, 50 metres beyond the previous western limit of the lens, intersected 5.2 metres grading 3.03 per cent copper, 18.6 per cent zinc, 65.4 grams per tonne silver, 0.93 gram per tonne gold (Exploration and Mining in British Columbia 2004, page 26).

A National Instrument 43-101 compliant resource estimate at Kutcho Creek has outlined measured and indicated resources at the Kutcho deposit (using a 0.5 per cent copper cutoff) of 13.06 million tonnes grading 1.94 per cent copper, 2.59 per cent zinc, 33.7 grams per tonne silver and 0.41 gram per tonne gold (Western Keltic Mines, Press Release, January 11, 2005). The indicated resource estimate for the Esso West deposit is 2.12 million tonnes grading 3.26 per cent copper, 5.86 per cent zinc, 75.7 grams per tonne silver and 0.71 gram per tonne gold (using a 1.5 per cent copper cut-off) (Western Keltic Mines, Press Release, January 11, 2005).

Further property work plus additional statistical analysis of drill data has lead to an updated Mineral Resource value for the property. From the Company news release is the following table:
____________________________________________________________________________

SUMMARY

Main deposit Tonnage (t) Cu% Zn% Ag g/t Au g/t

Measured 2,937,583 1.83 2.65 27.98 0.39
Indicated 12,712,675 1.60 2.04 25.70 0.31
Measured plus indicated
15,650,258 1.65 2.15 26.13 0.32
Inferred 811,103 0.95 1.92 24.17 0.33

Sumac deposit

Inferred 10,605,030 0.94 1.45 13.96 0.14

Esso deposit

Indicated 2,040,445 2.24 3.96 37.70 0.49
Inferred 442,506 2.47 4.15 38.09 0.53

Total

Measured plus indicated
17,690,703 1.71 2.36 27.46 0.34
Inferred 11,858,639 1.00 1.58 15.56 0.17
___________________________________________________________________________


The qualified person as defined in NI 43-101 responsible for the mineral resource estimate is Tim Carew, P.Geo. The complete NI 43-101 technical report is filed on SEDAR (2007 - June).

Western Keltic Mines Ltd. was acquired by Sherwood Copper Corp. in 2008. And in November 2008, Sherwood and Capstone Mining combined to become Capstone Mining Corp. In 2010, Capstone released an updated resource estimate for the Esso deposit within the Kutcho project. The estimate is as follows (Stockwatch News Release - December 6, 2010):
----------------------------------------------------------------------------
Classification Tonnes Cu(%) Zn(%) Au(g/t) Ag(g/t)
Indicated 1,816,200 2.69 6.18 0.66 64.8
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In 1972 and 1973 respectively, Sumac Mines Ltd., controlled by Sumitomo Metal Mining Co. Ltd. and Imperial Oil Ltd. (Esso Minerals of Canada), independently located and staked the ground covering the Kutcho Creek polymetallic volcanogenic massive sulphide deposits. Development work, carried out independently but cooperatively by the two companies, occurred mainly between 1973 and 1984 and defined three massive sulphide zones. Greater than 50,000 metres of drilling was completed and a 218-metre crosscut producing greater than 3000 tonnes of ore for bulk sampling was excavated. This work resulted in Esso owning the east end of the outcropping Kutcho deposit (lens) and the deep Esso West deposit (lens). Sumac ground covered the downplunge western portion of the Kutcho deposit and the Sumac deposit (lens). Further work was done between 1985 and 1987, apparently concentrating on exploration outside the main deposit area. In early 1989, Esso Minerals sold its portion of the property to Homestake Mining (Canada) Limited who subsequently sold a minority interest to American Reserve Mining Corp. A joint equal ownership agreement between Homestake (with American Reserve) and Sumac is still in force (R. Britten, personal communication, 1995).

In 2011, an airborne electromagnetic survey was conducted over the Kutcho property on behalf of owner/operator Kutcho Copper Corporation using Geotech Ltd.’s proprietary VTEM system for a total of 1649.4 line kilometres covering a 147.2 square kilometre area.

Bibliography
EMPR EXPL 1975-E188-189; 1976-E189-190; 1977-E230-231; 1978-E261; 1979-286; 1980-480; 1981-84; 1982-387; 1983-532; 1984-391; 1996-B12; 2004-26
EMPR FIELDWORK 1975, p. 86; 1976, p. 75; 1977, p. 43; 1982, p. 179; 2010, p. 99
EMPR GEM 1973-510; 1974-343-348
EMPR GEOL 1976, p. 128
EMPR MAP 65 (1989)
EMPR MER 1984, p. 8; 1985, p. 9; 2003-11, 2004-6
EMPR OF 1992-1; 1992-3; 1996-11; 1998-10; 1999-2
EMPR PF (Smithers; Notes from Andres talk, Dec. 1977; Western Keltic Mines Inc.: Kutcho Creek Project brochure; Exploration & Development Review ’95: Summary of Potential Producers, Mining Review Summer 1995; Times Colonist: Talk Politics, Jim Hume, 1984; Kutcho Creek Interest Purchased, American Reserve Mining Corp., Homestake Mining Ltd. 1990;)
EMPR PF Chevron (Kutcho Creek Information Summary, Esso Minerals Canada, 1988)
EMPR PF Cyprus Anvil (Cupriferous Iron Sulphide Deposits - Kutcho Creek, D.E. Pearson; Re: Unit 8a - Kutcho Creek, G. Jilson, 1976; New copper find hailed in northern B.C., L. Taylor; Diamond Drilling on the Kutcho Group, Sumac Mines Ltd., 1974)
EMPR PF Tom Schroeter (Notes – Kutcho, 1990; Letters Re: Kutcho, 2005; Map Sections – Kutcho, 2005; Partial Report – Kutcho, 2003; News Clipping – Kutcho, 2006; Press Releases - Kutcho deposit, Western Keltic Mines Ltd., 2005; Press Releases – Kutcho, Western Keltic Mines Ltd., 2006; Press Releases – Kutcho, Western Keltic Mines Ltd., 2007; Report - Kutcho Creek Visit, 1975; Report - Detailed Mine Develeopment Plan - Stage II Report - Kutcho Creek Project, Sumac Mines Ltd., 1986; Report - Stage I Update - Kutcho Creek Project, Sumac Mines Ltd., 1983; Report - Geology o the Kutcho Creek Volcanogenic massive sulphide deposits, Bridge, D.A. and Marr, J.M.; Letters Re: Kutcho Creek, K.D. Ferguson, 1989; Geological Maps - Kutcho Creek, undated; Field Notes - Kutcho Creek, 1982; Sketch Section Map - Kutcho Creek Deposit, undated; Geological Section Map - Kutcho Creek Deposit, 1979; PDAC 2006- Kutcho Creek Cu-Zn Project, Western Keltic Mines Ltd., 2006; Re: Activities Report, P. Wilton, 2005; Conference Notes - Kutcho Creek, 2006; Press Release - Kutcho Project, Western Keltic Mines Ltd., 2007; News Clipping - New copper find hailed in northern B.C., L. Taylor, 1976; News Clipping - B.C. needs more tha PR spin to ensure a prosperous future, 2006; Re: Letter dated November 15th, 1982, Sumac Mines Ltd.; Re: Highlights fom MDRU VMS Update, D. Alldrick, 1994; Northwest Mining Associations 2003 Abstract Booklet - Kutcho Creek, 2003; Re Daily Report, H.M. Visagie, 2007; Summary of U-Pb age and isotopic infomation - Kutcho Creek, F. Childes, 1994; Re: Kutcho Creek Project, E.M. Berthelsen, 1987; Property Visit - Kutcho Creek, 1976; Panoramic Photo - Kutcho Creek, 1976; Re: NW Region - Weekly Report, B. Wally; 1998; Geology and claim map – Kutcho, undated; Mineral Claims Map - Kutcho Creek Project, Sumac Mines Ltd., 1978; Geological Map Section – Kutcho, 1982; Press release - Kutcho Creek Cu-Zn project, Western Keltic Mines Ltd., 2006)
EMR MP CORPFILE (Sumac Mine Ltd.; Sumitomo Metal Mines Canada Ltd.; Imperial Oil Ltd.)
GSC P 78-1A, pp. 25-27; *86-16, pp. 29-31
GSC OF 2262; 2779
GSC BULL 504
GSC MAP 1418A; 1712A
CIM *Special Volume 37 (1986), pp. 115-128
GCNL #42(Feb.28),#198(Oct.12), 1990; *#54(Mar.18),#130(Jul.8), 1991; #9(Jan.14),#135(July 14), 1992
N MINER Sept.24, 1990; July 15, 1991; Jan.27, 1992; Aug.4, 1997; Mar.8, Nov.8, 2004; Jan.17, 2005; Jul. 9, 2007
PR REL Western Keltic Mines Inc., Sept.18, Dec.8, 2003; Mar.14, Aug.17, Sept.8,30. Oct.18, 2004, Jan.11, Apr.11, Jul.7, Aug.31, Oct.27, Dec.15, 2005
Stockwatch Dec.6, 2010
Chevron File

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