Mineral deposits of Arctic Canada: excerpts from a chapter in "Mineral deposits in the Arctic"

Abstract

The geology of Arctic Canada is divided into the cratons or granitic and metamorphic roots of the Canadian shield which contain much of the gold, copper, nickel, iron, uranium, rare earth elements and diamond deposits. The bounding Mesoproterozoic to Phanerozoic platforms, basins and accreted terrains of the Interior platform and Canadian Cordillera, which extend into the High Arctic, contain much of the zinc, lead, gold, silver, copper, molybdenum and tungsten resources. Basement nuclei in the Canadian shield are the four Archean cratons. Oldest of these is the Slave craton (4030-2550 Ma) on the west side of the shield. It is bound by Paleoproterozoic orogens: Thelon-Taltson to the east, Wopmay to the west and the Athapuskow aulcogen to the south in the east arm of Great Slave Lake. The Slave craton is associated with orogenic gold, volcanogenic massive sulphides (VMS), diamond-rich kimberlites and a large REE deposit. Lying to the east and underlying most of the remaining parts of the Canadian shield across the Canadian Arctic are the Rae (3250-2580 Ma) and Hearne (2740-2540 Ma) cratons. Significant in the Meso- to Neoarchean Rae craton are supracrustal rocks containing important resources of iron, orogenic gold of Paleoproterozoic age, uranium associated with a sub- Paleoproterozoic unconformity, nickel and commercially significant diamond-rich kimberlites. Known resoources in the Hearne craton include nickel, copper, platinum group elements (PGE), uranium and VMS. The fourth craton is represented by the Superior craton, mostly located south of latitude 60 but also exposed in the northern extremity of Quebec. It is bound to the north by the Paleoproterozoic Cape Smith belt (1870-1800 Ma), part of the circum-Superior Trans-Hudson orogen. This belt is noted for its important resources of nickel, copper and platinum group elements. The other significant Paleoproterozoic belt is represented by the Wopmay orogen (1890-1840 Ma) which lies west of the Slave Craton. This features an eastern sedimentary belt and, to the west, the plutonic and volcanic rocks of the Great Bear magmatic zone. Noteworthy resources include iron oxide-copper-gold (IOCG), polymetallic veins and vein uranium. The Precambrian cratons and Paleoproterozoic basins are fringed to north and west by Mesoproterozoic to upper Paleozoic shelf carbonate sequences. These rocks contain carbonate-hosted (MVT) zinc-lead deposits. Also present in this realm are iron deposits, notably the very large Crest deposit in Neoproterozoic strata. Southwestward the shelf succession gives way to Cambrian to Devonian deep water sediments of the Selwyn Basin. Important resources within the Selwyn Basin include three shale-hosted zinc-lead deposits in the Yukon and two significant VMS copper-zinc deposits. The western part of the Yukon is dominated by Jurassic and Cretaceous accreted terranes and associated granitoid rocks. This is a key realm for gold, polymetallic silver-lead-zinc veins and nickel-copper-PGE. Also associated with Mesozoic intrusives are tungsten and copper skarns, and copper-molybdenum porphyry deposits. Rounding out the resources of the Yukon are eleven gold placer districts of which the Klondike is most significant.