In a sense, subduction zones are the opposite of divergent boundaries, areas where material rises up from the mantle and plates are moving apart. An oceanic plate ordinarily slides underneath a continental plate this often creates an orogenic zone with many volcanoes and earthquakes. They may be formed by subduction zones, which is an area on Earth where two tectonic plates meet and move towards one another, with one sliding underneath the other and moving down into the mantle, at rates typically measured in centimeters per year. Volcanic belts may be formed by multiple tectonic settings. Volcanic belts are similar to a mountain range, but the mountains within the mountain range are volcanoes, not mountains that are formed by faulting and folding by the collision of tectonic plates. The Abitibi greenstone belt in Ontario and Quebec, Canada is one of the world's largest greenstone belts. They are thought to have formed at ancient oceanic spreading centers and island arc terranes. These are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that form what are known as greenstone belts. It contains over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 to 1,200 million years old. The deeply deformed and eroded remnants of ancient volcanic belts are found in volcanically inactive regions such as the Canadian Shield. For example, volcanoes in Mexico and western North America are mostly in volcanic belts, such as the Trans-Mexican Volcanic Belt that extends 900 kilometres (560 mi) from west to east across central-southern Mexico and the Northern Cordilleran Volcanic Province in western Canada. These areas usually form along tectonic plate boundaries at depths of 10 to 50 kilometres (6.2 to 31.1 mi). Volcanic belts are found above zones of unusually high temperature (700 to 1,400 ☌ (1,292 to 2,552 ☏)) where magma is created by partial melting of solid material in the Earth's crust and upper mantle. Other terms are used for smaller areas of activity, such as volcanic fields. The Trans-Mexican Volcanic Belt in MexicoĪ volcanic belt is a large volcanically active region.
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