Ring of Fire the east and the Okhotsk Sea to the west. Immediately offshore along the Pacific coast of the peninsula runs the 10,500-m-deep Kuril-Kamchatka Trench, where rapid subduction of the Pacific Plate fuels the intense volcanism. Almost all types of volcanic activity are present, from stratovolcanoes and shield volcanoes to Hawaiian-style fissure eruptions. Over 30 active volcanoes and hundreds of dormant and extinct volcanoes are in two major volcanic belts. The most recent activity takes place in the eastern belt, starting in the north at the Shiveluch volcanic complex, which lies at the junction of the Aleutian and Kamchatka volcanic arcs. Just
Circum-Superior Belt margin. The last collision occurred on the southeastern portion of the Superior craton to produce the Grenville orogeny 1,100 million years ago. Because most of the Circum-Superior Belt was formed by widespread mafic-ultramafic magmatism 1,884 to 1,864 million years ago along the Superior craton margin during these orogenies, a number of different suggestions have been made to explain the questionable origins of this large igneous province. It is also not clear if the Circum-Superior Belt has a single origin or it has several origins. Suggestions include back-arc rifting, foredeep flexure, mantle plumes and the breakup of a microcontinent. The geochemical