Exploration and mining in the Southwest Region, British Columbia Bruce Northcote1, a 1 Regional Geologist, British Columbia Geological Survey, Ministry of Energy, Mines and Petroleum Resources, 300-865 Hornby Street, Vancouver, BC, V6Z 2G3 a corresponding author: [email protected] Recommended citation: Northcote, B., 2019. Exploration and mining in the Southwest Region, British Columbia. In: Exploration and Mining in British Columbia, 2018. British Columbia Ministry of Energy, Mines and Petroleum Resources, British Columbia Geological Survey, Information Circular 2019-01, pp. 101-113. 1. Introduction 2. Geological overview The Southwest Region (Fig. 1) has a long history of mining. Metallogeny in British Columbia is closely linked to the This history includes: the use of native copper by First Nations; tectonic evolution of the Canadian Cordillera, fi rst as an silver, gold and coal mining by the mid-19th century; mining of accretionary orogen consisting of allochthonous terranes that iron in the mid-20th century; and substantial copper production were welded to and deformed with the western margin of throughout the 20th century. Although mining and exploration ancestral North America primarily during the Jurassic and then for metal and coal continue in the region, most mining is for as the site of post-accretionary tectonism and magmatism (e.g., construction materials, mainly aggregates for local markets. Nelson et al., 2013). The area has one major polymetallic metal mine, Myra Falls T he Southwest Region includes parts of the Insular, Coast, (Nyrstar N.V.), one coal mine, Quinsam (ERP Compliant and Intermontane physiographic regions. Most of the area Fuels LLC), and numerous industrial minerals and aggregate is underlain by rocks of the Wrangell terrane and the Coast operations. In the summer of 2017, Nyrstar returned Myra Plutonic complex (Fig. 1). Wrangellia is a Devonian to Jurassic Falls to production, having been on care and maintenance island arc terrane that underlies most of Vancouver Island since 2015. Similarly, Quinsam, on care and maintenance since and Haida Gwaii. The oldest rocks on Vancouver Island are 2016, returned to production in 2017, after being purchased by Devonian volcanic arc andesites, basalts, breccias, tuffs and ERP Compliant Fuels LLC. As of September 2018, Myra Falls tuffaceous sediments of the Sicker Group and allied intrusive was producing concentrate and shipment was expected late rocks, overlain by Mississippian-Permian limestones, argillites, in the year. The Quinsam mine is expected to produce about and minor conglomerate of the Buttle Lake Group. This 200,000 t in 2018. Mine site exploration began at Myra Falls Paleozoic basement is exposed in two major uplifts on southern late in 2017 and continued in 2018. A permitted exploration and central Vancouver Island. The Cowichan anticlinorium program by Quinsam, also began late in 2017 and continued and the Buttle Lake anticlinorium host the past volcanogenic in 2018. massive sulphide polymetallic producer at Mount Sicker and Signifi cant off-lease exploration drilling programs in 2018 the current mine at Myra Falls. include Surespan Gold, Pemberton Hills and Ladner Gold. Unconformably overlying the Paleozoic rocks are Middle to About 25 active exploration projects were tracked; most were Upper Triassic oceanic fl ood basalts and related sedimentary small scale. BURNCO Rock Products Ltd.’s large aggregate rocks of the Vancouver Group. The upper part of the Vancouver project on Howe Sound, BURNCO Aggregate, obtained Group contains numerous skarn occurrences adjacent to Jurassic provincial environmental certifi cation in 2018; Fisheries and intrusions (Island Plutonic suite). The Tasu past producer on Oceans Canada considered that the project was unlikely to Haida Gwaii is one of the larger examples of numerous iron harm the environment. and iron-copper skarns. Between 1914 and 1983, it produced Estimates for exploration expenditures, drilling programs, 12 Mt of iron concentrate as well as copper, gold and silver. and other metrics were captured in the British Columbia Mineral The Vancouver Group is overlain by arc rocks of Bonanza and Coal Exploration Survey, a joint initiative of the Province Group (Upper Triassic-Middle Jurassic), which consist of of British Columbia Ministry of Energy, Mines and Petroleum a volcano-sedimentary succession and subaerial basalt to Resources, the Association for Mineral Exploration in British rhyolitic fl ows and tuffs (Nixon and Orr, 2007). The Bonanza Columbia, and Ernst & Young LLP. For the Southwest Region, Group north of Holberg Inlet host the past-producing Island exploration expenditures were estimated at $7.8 million and Copper Cu-Mo-Au porphyry deposit and other undeveloped exploration drilling was estimated at approximately 39,800 m porphyry and epithermal prospects where they are intruded by (Clarke et al., 2019; Ernst &Young LLP (EY), 2019, in press). Island Plutonic suite granodiorite and quartz diorite. On the east coast of Vancouver Island, in the Strait of 101 Provincial Overview of Exploration and Mining in British Columbia, 2018. British Columbia Geological Survey, Information Circular 2019-01 Northcote Prince Rupert Houston Fort St. James Burns Lake Masset Kitimat Fraser Lake Vanderhoof Prince George Hixon Wells Foreland Quesnel Intermontane Insular Omineca Gold Standard !ÉGoldcrest !É Bella Coola Coast Cordilleran PACIFIC OCEAN morphogeological Williams Lake Goldstar belts !É Alexis Creek Property status coloured by project type !( Operating Mine* 100 Mile House ÌÌ !( Mine in Care and Maintenance** !( Proposed Mine !É Exploration Project *Operated in, or for a portion of 2018 Southwest **Operated within the last 3 years Regional WXWX Bute Inlet Districts Cache Creek Project type Skyhigh!É Ì Ì Garibaldi Pumice Coal Port Hardy Ì Haddington Island WX !( Cu-Mo, Cu-Au-Ag, Mo (porphyry) Pemberton Hills!É Orca WX Mount Meager Apple Bay WX Ì !( Precious metal ÛÚWX ÌÌ !( Base and precious metal LeMare Lake ÌLeo D'Or !É # !( WX WX Lytton Cobalt, base and precious metal Benson Lake !É !( Texada Quarry Merritt Ni-Cu-Co-precious metal White Fang !( Tungsten Van Anda !( Specialty metal Surespan Gold!É Quinsam Ashlu Campbell River !É WX Jade Ì Ta hs is Ì Blubber Bay Dancer WX Industrial mineral WX WX !É WXWX WX !ÉÛÚ Earle Creek ÛÚ Aggregate projects Ì Mount Washington ÌÌ Ì Ì Burnco Aggregate Ladner Gold Myra Falls !( Hardy Island WX ÛÚ !É Geology 0 Kilometres 100 Ì ÛÚ Lode Gold Prosper Selchelt Carbonate Pitt River !É !É Ì # Post accretionary assemblages Sechelt Mine VancouverÛÚ WX Port Alberni Ì !É Intrusives Supracrustal Transportation Valdes Island Giant Copper Neogene to WXÛÚ Quaternary volcanics Pacific Copper WX Ì Te r ra n es Î Port !É Ì ÌWahleach Creek Lara Ferry route Jasper !É Outboard Alexander Stikinia Road !É Cox Station Cache Creek and Wrangellia Quesnellia Rail line K2 UNITED STATES OF AMERICA affiliates WX SumaV6KDOH Major faults Ì Victoria Fig. 1. Mines, proposed mines, and selected exploration projects, Southwest Region, 2018. Terranes from Nelson et al., 2013). 102 Provincial Overview of Exploration and Mining in British Columbia, 2018. British Columbia Geological Survey, Information Circular 2019-01 Northcote Georgia, and on the western mainland, Wrangellia is buried by Cretaceous or Paleocene to Early Eocene seamounts. The Leech rocks of the Nanaimo Group, an Upper Cretaceous continental River fault marks the boundary of Pacifi c Rim and Crescent to marine molassoid succession containing debris derived from terranes. The Metchosin Igneous complex, a partial ophiolite unroofi ng of the Coast Belt and northern Cascades (Mustard, and northernmost extent of the Coast Range basalt province 1994). The Comox Formation, the basal unit of the Nanaimo (Massey, 1986), contains three tholeiitic intrusion-hosted past Group, hosts economically important coal deposits that were producers of copper and precious metals, the most signifi cant mined historically in the Nanaimo area now near Campbell of which was the Sunro mine. River. The southeastern Coast Belt, north of the international The Coast Mountain range is underlain by the Coast Plutonic border is underlain by the Nooksack-Harrison and Chilliwack complex, a large northwest-trending batholith consisting terranes (equivalent to Stikinia; Monger and Struik, 2006), and largely of diorite, quartz diorite, tonalite and granodiorite calc- the Bridge River, Cadwallader and Methow terranes, allied alkaline rocks with less abundant high-grade metamorphic with the main Cache Creek terrane (Fig. 1). These represent rocks. For the most part, uplift and erosion have removed the slices of oceanic and arc-related rocks enclosed between levels at which epithermal and porphyry style mineralization Intermontane and Insular terranes during Middle Jurassic to form, with some exceptions. At the southern end of the Coast Middle Cretaceous regional sinistral faulting (Bustin et al., Plutonic complex, economically important deposits occur in 2013; Monger and Brown, 2016). Gambier Group equivalent pendants of the Gambier Group, overlapping Late Jurassic to overlap deposits and parts of the Nooksack-Harrison terrane Mid-Cretaceous arc-related volcanic and sedimentary rocks. are prospective for VMS mineralization. The Coquihalla The most productive of these deposits was the Britannia mine, Serpentine belt, along the Hozameen fault between the Bridge a Kuroko-type polymetallic volcanogenic massive sulphide River terrane to the west and the Methow terrane to the