The Teako property occurs in a region which is rich in mineral endowment, one which is known both for the number and the variety of mineral deposits, and which is home to a number of important active and past-producing mines. A discussion of mineralization and deposit styles in the region is useful in indicating possible metallogenic models that could be applicable on the Teako property.
Polymetallic Vein (Pb-Zn-Ag +/- Au) Deposits
Polymetallic veins are a common deposit type in the region, and, in fact, rank as the most common deposit type in British Columbia. Veins are sulfide-rich, with a gangue of predominantly quartz and/or carbonate. Pyrite is common and principle ore minerals include galena, sphalerite, sulfosalts, native silver, chalcopyrite, arsenopyrite and stibnite. Individual veins can vary from a few centimetres to in excess of 3 metres in width and can extend for up to 1000 metres along strike and down dip. Veins commonly split and splay forming sets of multiple veins, or break into broad stockwork or breccia zones to 10’s of metres in width. Wall rock alteration around vein systems is limited, typically extending a few metres or less from veins.
Polymetallic veins can be hosted by any rock type and are especially common peripheral to porphyry deposits, where they are genetically related to the same intrusive host. Where host rocks are sediments, veins are typically emplaced along faults and fractures. Where an intrusive source is present, the veins are commonly located in the country rock close to the intrusive contact (Lefebure and Church, 1996).
Numerous occurrences of polymetallic veining, associated with intrusives of the Babine and Bulkley suites, are known in the region and in the immediate vicinity of the Teako property. At the historic Silver Standard mine just north of Hazelton, a total of 205,000 tonnes, at an average grade of 1161 g/t Ag, 2.3 g/t Au, 6% Zn and 3.9% Pb was mined from a series of quartz and quartz-carbonate veins during the period 1913-1922 and 1948-1989. Veins are hosted within a thick section of Bowser Lake Group sediments, which have been cut by small granitic intrusive bodies of the Eocene Babine suite. Quartz veins, averaging 0.3 – 0.9 metres in width, occupy northeast trending fault zones. A series of parallel, northeast trending, moderate to steeply southeast dipping veins, lie within a 1600 metre zone trending 110º. The most productive veins occur near the center of a domed area on the west limb of a broad anticline. Veins are mineralized with sphalerite, pyrite, arsenopyrite, galena, pyrrhotite, tetrahedrite and chalcopyrite. A characteristic tan coloured carbonate (+ silica, feldspar) alteration envelope is present around the veins (Kindle, 1940; Minfile 093M 049). The host rocks, vein style and general setting at the Teako Property have similarities to the Silver Standard veins.
The historic Cronin-Babine mine northeast of Smithers is another local example of polymetallic veining. Sulfide mineralization occurs as disseminations in the host rock, in quartz stockworks, and in massive sulfide and quartz-sulfide shear veins. These veins typically strike northeast, dip moderately to the northwest, and range in width from 0.3-1.0 metres. Mineralization is hosted by Bowser Lake Group sediments and by Eocene rhyolite intrusives which cut the sediments. Historic production from the Cronin mine (1917 – 1974) is approximately 26,000 tonnes grading 316 g/t Ag, 5.9% Zn, 5.3% Pb and 0.34 g/t Au (Minfile 093L 127).
Just south of Hazelton, in the Rocher Deboule District, sediments of the Bowser Lake Group are hornfelsed and intruded by porphyritic granodiorite of the Bulkley intrusive suite. Tungsten (+/- copper, silver, gold, lead and zinc) mineralization occurs in veins and pegmatite zones, that are genetically related to the intrusions. Veining occurs primarily within the intrusive rocks, but does extend a short distance into the surrounding hornfelsed sediments. At the Rocher Deboule and Victoria mines, some 123,000 tonnes was mined from 1915-1954, at an average grade of 21.5 g/t Ag, 1.3 g/t Au, 2.3% Cu and 0.03% W. Ore is primarily chalcopyrite in a quartz-hornblende gangue, with variable amounts of magnetite, pyrrhotite, arsenopyrite, pyrite, tetrahedrite and molybdenite. At the Red Rose mine, just over 100,000 tonnes averaging 0.97% W was produced between 1942 and 1954, primarily from a single quartz-rich pegmatite vein (Kindle, 1940; Minfile 093M 067, 071, 072).
Porphyry Copper (+/- Gold, Molybdenum) Deposits
Porphyry deposits are large bulk-mineable deposits that are genetically related to, and occur within or adjacent to, porphyritic intrusions. Mineralization occurs as stockworking veins, veinlets and closely spaced fractures, or as disseminations. The mineralization occurs within large zones of hydrothermally altered rock (up to 10 square kilometres in size), with characteristic, large-scale zoned metal and alteration assemblages. Higher grade zones of mineralization occur within larger areas of lower grade mineralization and deposit boundaries are determined by economic factors.
Porphyry deposits are classified as alkalic or calc-alkalic, on the basis of host rock chemistry. Calc-alkalic porphyry copper-molybdenum and alkalic porphyry copper-gold deposits are both important deposit types within B.C. Examples of calc-alkalic deposits include the world-class Highland Valley deposits south of Kamloops, the Bell and Granisle deposits near Smithers, and the Huckleberry mine south of Houston. Examples of significant alkalic copper-gold porphyry deposits in B.C. include Mt. Polley, Mt. Milligan, Red Chris and Galore Creek.
B.C. calc-alkalic porphyry deposits range in size from less than 50 million tonnes to greater than 900 million tonnes, with grades in the range of 0.2-0.5% Cu, <0.1-0.6 g/t Au, 1-3 g/t Ag and trace to 0.04% Mo. Typical B.C. alkalic porphyry deposits range in size from less than 10 million tonnes to greater than 300 million tonnes, with grades in the range of 0.2-1.5% Cu, 0.2-0.6 g/t Au and > 2 g/t Ag. Mo content is negligible. (Panteleyev, 1995a,b; Sinclair, 2007).
Numerous important porphyry deposits and occurrences of the calc-alkalic type are known in the vicinity of the Teako property (Carter, 1981). In the Babine Lake area northeast of Smithers, more than a dozen such deposits or occurrences are known, of which the largest mined to date have been the Bell and Granisle deposits. A combined total of 130 million tonnes at an average grade of 0.4% Cu, 0.15 g/t Au and 0.75 g/t Ag was produced from the Bell and Granisle Mines from 1966-1992. Mineralization is associated with Eocene-aged Babine intrusions (Dirom et al, 1995). The Morrison – Hearne Hill deposit, located about 20 kilometres north of the Bell mine, is another examples of calc-alkalic copper-gold porphyry style mineralization associated with Babine intrusions (Ogroyzlo et al, 1995). The deposit contains a measured plus indicated resource of 238 million tonnes grading 0.37% Cu and 0.18 g/t Au. Citing concerns for the Morrison Lake sockeye salmon population, late in 2012 the BC government denied Pacific Booker Minerals Inc. the Environmental Assessment Certificate that the company required to develop the proposed 30,000 tonne per day open pit mine, (Pacific Booker Minerals news release, October 1, 2012).
The Huckleberry deposit, south of Houston, is an example of calc-alkalic porphyry copper-molybdenum mineralization in the region which is associated with the Bulkley suite of intrusives. Huckleberry is an active open pit mine, which is currently producing at an average rate of 16,000 tonnes per day. It is owned 50% by Imperial Metals Corp. and 50% by a consortium of Japanese companies. Nearby, Gold Reach Resources has been aggressively exploring the Seel and Ox porphyry deposits on their Ootsa property, and has recently announced an Inferred Resource for the Seel deposit of 67.7 million tonnes grading 0.21% Cu, 0.17 g/t Au, 0.015% Mo and 2.02 g/t Ag (or 0.39% CuEq), using a cut-off grade of 0.2% CuEq. There is an additional Inferred Resource (for the combined Seel and Ox deposits) of 463.5 million tonnes at a grade of 0.31% CuEq, at the same cut-off grade (Gold Reach Resources news release, Feb. 19, 2013).
Another calc-alkalic porphyry occurrence in the region is Victory Mountain Ventures’ Louise Lake property west of Smithers, which contains an Indicated Resource of 6 million tonnes grading 0.21% Cu, 0.2 g/t Au, 0.006% Mo and 0.98 g/t Ag (or 0.37% CuEq), plus an Inferred Resource of 141 million tonnes grading 0.43% CuEq (both assuming a 0.25% CuEq cut-off grade) (www.victorymv.com)
Porphyry Molybdenum Deposits
Porphyry molybdenum deposits belong to the same general category of deposit as the porphyry copper deposits described above. Mineralization occurs as stockworks of molybdenite-coated fractures and molybdenite-bearing quartz veinlets, in felsic intrusives and surrounding country rock. Deposits tend to be low grade, but very large. Typical BC examples range from 30 to 300+ million tonnes in size, with grades ranging from 0.09 to 0.11% Mo (Sinclair, 1995).
The largest developed BC porphyry molybdenum deposit is the active Endako mine, located approximately 115 kilometres southeast of the Teako property. Mining has been ongoing at Endako since 1965 and the mine has a projected life through at least 2025. Thompson Creek Metals recently commissioned a new milling facility and is currently mining the deposit at a rate of 50,000 tonnes per day. Production (1965-2010) from Endako totals 392 million tonnes grading 0.06% Mo. As of 2011, the mine had Proven and Probable Reserves totaling 300 million tonnes at a grade of 0.046% Mo (Minfile 093K 006; www.thomsponcreekmetals.com).Another example of porphyry molybdenum mineralization in the region is the Davidson prospect on Hudson Bay Mountain near Smithers. There, porphyry-style molybdenum mineralization is hosted by altered Hazelton Group volcanics, and by granodiorite and quartz porphyry intrusives of the Bulkley suite. The deposit is located 300 to 450 metres below surface and is accessed via a 2 kilometre long tunnel. In 2007, Thompson Creek Metals Company Inc. conducted a feasibility study on the Davidson deposit. A combined Measured and Indicated Resources of 77.2 million tonnes grading 0.169% Mo at a cut-off grade of 0.12% Mo was reported (Carter, 1981; Thompson Creek Annual Report 2007; www.thompsoncreekmetals.com).
Porphyry molybdenum mineralization also occurs at Mount Thomlinson, about 40 kilometres north of Hazelton, at the Lucky Ship deposit south of Houston, and at the Kitsault deposit at Alice Arm. In the immediate vicinity of the Teako property, porphyry molybdenum mineralization is known in the Sedan Creek area. Molybdenum mineralization has also been noted on fractures in granitic intrusive along the southeast bank of the Skeena River, about 3 kilometres upstream from Cedarvale, as well as southwest of the property near the headwaters of South Lorne Creek.
Epithermal Au-Ag Deposits (and Transitional Epithermal-Porphyry Deposits)
Epithermal deposits are epigenetic deposits, typically hosted by coeval or older volcanic rocks, which result from high-level hydrothermal systems. Ore bodies tend to be steeply-dipping, upward-flaring veins which are localized along structures. Mineralization may also occur in permeable lithologies. Vein systems can be laterally extensive, with strike extents commonly exceeding 1000’s of metres. Within these laterally extensive vein systems, ore shoots have a relatively restricted vertical extent (100’s of metres) and are commonly localized at dilation zones along structures. Deposits are characterized as high, intermediate or low-sulfidation systems, based on alteration, gangue and ore mineral assemblages.
In epithermal deposits, ore-bearing minerals occur within quartz (+/- chalcedony, calcite, fluorite, barite, adularia, illite) veins, stockworks and breccias. The veins commonly exhibit open-space filing and multi-episodic textures. Common metallic minerals include native gold, electrum, argentite and pyrite with lesser amounts of sphalerite, chalcopyrite, galena, tetrahedrite and sulfosalts. Proximal to veins, alteration consists of silicification, argillic and advanced argillic assemblages. Propylitic alteration occurs distally and at depth (Panteleyev, 1996a,b; Simmons et al, 2005).
Epithermal and porphyry mineralizing systems both rely on a large hydrothermal system and a heat-source to drive the hydrothermal system. Some epithermal deposits are located above, or distal from, intrusion-related porphyry mineralization. In these cases, a continuum exists between the near-surface epithermal environment and the at-depth porphyry environment. The character of veining, alteration and mineralization of epithermal veins changes with depth and proximity to the intrusive heat source These deeper deposits are referred to as “subvolcanic Cu-Au-Ag (As-Sb)” deposits, or as “transitional porphyry – epithermal” deposits (Panteleyev, 1992, 1995c).
There are a number of mineral occurrences in the region which belong to the epithermal or transitional epithermal-porphyry classification of deposit and which support the potential for the Teako property to host mineralization of this type. The most significant deposit of this style in the region is the past-producing Premier mine, approximately 75 kilometres to the northwest, near Stewart. Historic production (1918 – 1996) from the Premier mine totals 6.6 million tonnes grading 9.4 g/t Au and 200 g/t Ag, plus minor amounts of lead, zinc and copper (Minfile 104B 054).
The Kalum property, 20 kilometres southwest of the Teako property, hosts a number of high-grade gold-bearing vein occurrences. In recent years, Eagle Plains Resources (and various joint venture partners) have carried out a significant amount of work on the property to explore both for high-grade gold-bearing veins, and for lower-grade bulk-tonnage gold mineralization. The property is underlain by Bowser Lake Group sediments which have been intruded by quartz monzonite, granodiorite and diorite intrusions of the Coast Plutonic suite. Zones of mineralization on the property are typically associated with the contact between the sediments and the intrusives. Hutter (2012) believes that, at least some of the mineralization on the property, best fits a transitional epithermal-porphyry model. Other zones of mineralization may be better characterized as polymetallic vein occurrences.
Other epithermal occurrences in the region occur in the Alice Arm area, 45 kilometres to the northwest of the Teako property, and in the Equity Silver area south of Houston, 75 kilometres to the southeast.