Question 14 of 18: Ownership of Natural Resources and Canadian Ore Deposit Models

Question 5: Ownership of Natural Resources and Canadian Ore Deposit Models (20 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Ownership of natural resources in Canada (2 marks). Under s.92A of the Constitution Act, 1867 (added 1982), the PROVINCES own and have exclusive legislative authority over non-renewable natural resources, forestry resources and electrical energy within their boundaries – mineral tenure, Crown mineral title, and most mining/exploration permitting is therefore provincial jurisdiction (in BC, administered under the Mineral Tenure Act and Mines Act). The FEDERAL government retains jurisdiction over the three Territories' Crown lands (though devolution agreements have transferred much day-to-day resource administration to territorial governments over the past two decades), federal lands, offshore resources beyond provincial boundaries, and matters of overriding federal interest (interprovincial/international trade, fisheries, federal environmental assessment under the Impact Assessment Act). A significant and growing layer alongside Crown ownership is the constitutionally-protected Aboriginal and Treaty rights of Indigenous peoples (s.35, Constitution Act, 1982), including the Crown's duty to consult and, where appropriate, accommodate, on resource decisions affecting asserted or established rights and title – increasingly formalized through impact-benefit agreements and, in some jurisdictions, revenue-sharing arrangements.

Each deposit type below is described with its geological setting, principal economic minerals, typical mining method, and relative operating-cost character, as would inform a Canadian resource-estimation context.

5.1 Volcanogenic Massive Sulphide (VMS)

Setting: Forms on or just below the seafloor at submarine volcanic centres (commonly bimodal felsic–mafic sequences), where hydrothermal convection driven by volcanic heat leaches metals from the volcanic pile and precipitates them as massive sulphide lenses on exhalation into cold seawater, typically capped by a chemical sediment ("exhalite") marker horizon and underlain by a stringer/stockwork feeder zone in altered footwall volcanics. Classic Canadian examples: Kidd Creek and Noranda (Abitibi), Bathurst (NB), Myra Falls (BC).

Minerals/products: Pyrite/pyrrhotite host with chalcopyrite (Cu), sphalerite (Zn), galena (Pb), and often significant Au/Ag credits; polymetallic Cu-Zn-Pb-Au-Ag is the classic VMS payable suite.

Mining method & cost: Steeply-dipping, lens-shaped, moderate-to-high-grade bodies are typically mined UNDERGROUND by cut-and-fill or longhole open stoping, giving relatively high mining unit cost per tonne offset by high polymetallic revenue per tonne; near-surface portions of larger systems may start as a small open pit.

5.2 Besshi Type

Setting: A sediment-hosted variant of the VMS clan, forming in a mafic volcanic-sedimentary (turbidite-dominated) submarine setting rather than a bimodal felsic-volcanic one – deposited from the same seafloor hydrothermal exhalative process but interbedded with, and partly reworked into, clastic sedimentary strata, giving more tabular, stratiform, laterally-continuous sulphide horizons than classic VMS lenses.

Minerals/products: Dominantly Cu-Zn (pyrite-chalcopyrite-sphalerite), generally with a lower Pb-Au-Ag credit than classic Kuroko-type VMS, reflecting the more mafic, sediment-dominated source system.

Mining method & cost: The more tabular, laterally continuous geometry (vs. classic VMS lenses) can favour longhole stoping or, where dip and thickness allow, room-and-pillar variants underground; unit mining cost is comparable to VMS generally but revenue per tonne is typically lower given the narrower (Cu-Zn only) payable-metal suite.

5.3 Evaporites (e.g. Permian Basin type)

Setting: Chemical sedimentary deposits precipitated by progressive evaporative concentration of restricted marine or lacustrine brine in an arid-climate basin with limited seawater inflow, producing a predictable vertical precipitation sequence (carbonate → gypsum/anhydrite → halite → potash/soluble salts) as brine concentration increases upward – classic examples include the Permian Basin (US) and, in Canada, the Devonian Elk Point Basin evaporites of Saskatchewan (world-class potash).

Minerals/products: Halite (NaCl), gypsum/anhydrite (CaSO₄), and economically most important, potash (sylvite KCl / sylvinite) – a bulk, low-unit-value, high-tonnage commodity (fertilizer feedstock).

Mining method & cost: Flat-lying, laterally extensive, moderate-depth (Saskatchewan potash typically ~1,000 m) beds are mined by conventional room-and-pillar underground mining (continuous miners) or, increasingly, SOLUTION mining (injecting water/brine, pumping saturated brine to surface for evaporative recovery) where depth or ground conditions favour it. Both methods have relatively LOW mining unit cost per tonne owing to bulk, continuous, highly mechanized extraction of a soft, flat-lying, laterally continuous bed, though solution mining trades mining cost for higher processing/evaporation energy cost.

5.4 Sedimentary Exhalative (SEDEX)

Setting: Like VMS, sulphides are precipitated from seafloor-venting hydrothermal brine, but SEDEX forms in an intracontinental or continental-margin rift/sag SEDIMENTARY basin (not a submarine volcanic centre) – brine expelled along syn-sedimentary extensional faults exhales into anoxic basinal water, precipitating laterally extensive, stratiform, FINELY LAMINATED sulphide beds interbedded with basinal shale, with comparatively little associated volcanic rock. Canadian examples: Sullivan (BC), Howard's Pass (Yukon/NWT), Red Dog-style systems.

Minerals/products: Dominantly Zn-Pb (sphalerite-galena) with variable Ag, generally lacking VMS's copper-rich stringer zone since the metal source is basinal brine/sediment leaching rather than a volcanic heat engine.

Mining method & cost: Large, laterally extensive, often thick, stratiform bodies (Sullivan was one of the world's largest Zn-Pb deposits) favour large-scale UNDERGROUND bulk methods (block caving, large longhole stopes) once depth precludes open pit; the sheer scale achievable in a well-continuous SEDEX body can deliver a relatively LOW mining unit cost per tonne despite being underground, owing to high-volume, low-selectivity bulk extraction.

5.5 Sudbury Igneous Complex (SIC)

Setting: A magmatic Ni-Cu-PGE sulphide system genetically tied to a large mafic-ultramafic impact-melt sheet (the Sudbury Igneous Complex, product of a ~1.85 Ga bolide impact into the Superior/Southern Province boundary) – immiscible sulphide liquid segregated from the impact-melt sheet settled to the base of the complex and into radiating/footwall offset dykes and embayments, forming contact-style and offset/footwall-style ore zones distinct from classic magmatic layered-intrusion Ni-Cu deposits elsewhere.

Minerals/products: Pentlandite (Ni), chalcopyrite (Cu), pyrrhotite, with significant platinum-group-element (Pt-Pd-Rh) and Au-Ag by-product credit – the classic Ni-Cu-PGE payable suite that has made Sudbury Canada's premier base-metal camp for over a century.

Mining method & cost: Deep, steeply-dipping, often narrow contact and footwall ore zones are mined UNDERGROUND (longhole open stoping, cut-and-fill in narrower high-grade zones) at some of the greatest mining depths in North America (>2,400 m at several Sudbury operations), giving high mining unit cost (deep ventilation, refrigeration, rock-burst/seismic ground control) offset by the high-value polymetallic (Ni-Cu-PGE) payable suite.

5.6 Athabasca Basin Unconformity Uranium

Setting: Ultra-high-grade uranium mineralization localized at (or immediately above/below) the unconformity between flat-lying, relatively undeformed Proterozoic Athabasca Group sandstone and its deeply-weathered, graphitic, structurally-reactivated crystalline basement (Saskatchewan) – formed by oxidizing, uranium-bearing basinal fluids migrating down through the sandstone and reducing (precipitating uraninite) on contact with reduced, graphitic basement fluids/lithologies along basement-penetrating fault structures, in some cases with mineralization extending well below the unconformity into "basement-hosted" style.

Minerals/products: Uraninite/pitchblende (UO₂), with the Athabasca Basin hosting the world's highest-grade uranium deposits by a wide margin (McArthur River/Cigar Lake historically averaging in the tens of percent U₃O₈, vs. a global average closer to 0.1–1%).

Mining method & cost: The combination of extreme grade (and correspondingly extreme radiological/criticality hazard) with weak, water-bearing unconformity-zone ground conditions drives HIGHLY SPECIALIZED, non-entry mining methods largely unique to this district – ground freezing ahead of development, raisebore/boxhole boring, and jet-boring or remote-controlled hydraulic mining (Cigar Lake) that never puts personnel directly against the ore face. Unit mining cost per tonne of ORE is exceptionally high relative to any other Canadian deposit type on this list, but because grade is so extreme, cost per POUND of U₃O₈ produced remains highly competitive globally – a reminder that mining unit cost per tonne and cost per unit of PAYABLE METAL can diverge sharply once grade is extreme enough.