to 2,210-million-year-old Ungava magmatic event was the source for the Nipissing sills of Ontario and have been historically important for copper, silver, and arsenic mineralization, and also have the potential to contain platinum group metals. A third major event is the 1,885‑ to 1,865‑million-year-old magmatism of the Circum-Superior Belt surrounding much of the Superior craton from the Labrador Trough in Labrador and northeastern Quebec, though the Cape Smith Belt in northern Quebec, the Belcher Islands in southern Nunavut, the Fox River and Thompson belts in northern Manitoba, the Winnipegosis komatiite belt in central Manitoba, and on the southern side of the Superior craton in the Animikie Basin of northwestern Ontario. Included within the Circum-Superior large igneous province are major nickel deposits of the Thompson and Raglan belts, which were likely derived from more than one magma source. The major 1,267‑million-year-old Mackenzie dike swarm magmatism in the western part of the Canadian Shield is the host for the highly prospected Muskox intrusion. Another significant event was the magmatism that formed the 723‑million-year-old Franklin dike swarm of Northern Canada and has been heavily mined for nickel, copper, and platinum group metals. The 230‑million-year-old accreted oceanic plateau, Wrangellia in British Columbia and Yukon, has also been searched for nickel, copper, and platinum group metals. Diatremes The kimberlite diatremes, or pipes, across Canada have also been important economically, because kimberlite magmas are the world's main source of gem-quality diamonds. Kimberlite pipes form when kimberlite magmas rise considerably from depths as great as . As the kimberlite magmas approach a depth of at least , the magma explodes violently through the Earth's crust, carrying fragments of rock that it has collected along the way and, in the right conditions, possibly diamonds, to the surface. The Eocene (ca. 55–50 Ma) age diatremes of the Lac de Gras kimberlite field in the central Slave craton of the Northwest Territories support two world-class diamond mines, called Ekati and Diavik. Ekati, Canada's first diamond mine, has produced of diamonds out of six open pits between 1998 and 2008, while Diavik, to the southeast, has produced of diamonds since its foundation in 2003. The diamondiferous Drybones Bay kimberlite pipe is the largest diatreme discovered in the Northwest Territories, measuring . Diamondiferous diatremes throughout the Northwest Territories and Alberta have the potential to make Canada one of the world's major producers of gem-quality diamonds. Recent activity Canada continues to be volcanically