Andean Volcanic Belt
Despite being a type location for calc-alkalic and subduction volcanism, the Andean Volcanic Belt has a broad range of volcano-tectonic settings, as it has rift systems and extensional zones, transpressional faults, subduction of mid-ocean ridges and seamount chains as well as a large range of crustal thicknesses and magma ascent paths and different amounts of crustal assimilations.
The Northern Volcanic Zone (NVZ) extends from Colombia to Ecuador and includes all volcanoes on the continental mainland of these countries.
Some volcanoes of the Northern Volcanic Zone, such as Galeras and Nevado del Ruiz that lie in densely populated highland areas, are significant sources of hazards.
Other silicic systems are Los Frailes ignimbrite plateau in Bolivia, and the caldera complexes of Incapillo and Cerro Galán in Argentina.
[2][4][5] The South Volcanic Zone (SVZ) extends roughly from Central Chile's Andes at the latitude of Santiago, at ca.
[7] The Principal Cordillera of Andes (east Santiago) rose in late Cenozoic and became extensively glaciated about one million years ago.
[8] The Maipo caldera exploded about 450 thousand years ago, leaving behind copious amounts of ash and ignimbrite rock that can be observed today both in Chile and Argentina.
[10] The southern part of the SVZ retained vigorous activity only in the west, especially around the Liquiñe-Ofqui Fault Zone,[10] while eastern volcanoes such as Tronador and Cerro Pantoja became extinct.
[9] The magmas of modern (Holocene) volcanoes in the Transitional Southern Volcanic Zone are derived from heterogenous sources in the Earth's mantle.
The AVZ extends south of the Patagonian Volcanic Gap to Tierra del Fuego archipelago, a distance of well over 600 mi (1,000 km).
[15] The lack of volcanism in central and northern Peru is widely attributed to a side effect of the flat-slab (low angle) subduction of the Nazca plate occurring there.
While the subduction of the Nazca Ridge has often been credited for causing this flat-slab and hence the lack of volcanism, many researchers find the gap too wide to be explained by this alone.
Recent studies conducted by Tibaldi et al. have discovered that the magma paths and dyke distribution in the Andean Volcanic Belt are not parallel to the maximum stress (E-W direction).
[16] Tibaldi et al. concluded that the magma path distribution is actually controlled by pre-existing structures and crustal weaknesses in the crust rather than the regional stresses.
Other significant back-arc volcanism regions include the Argentine Northwest where the Galán Caldera is located and the Andean foothills of Ecuador's Cordillera Real, where a series of alkaline volcanoes like Sumaco develops.
[2] The Andean Volcanic Belt represents a large geothermal province, with numerous hot springs, solfataras and geysers associated with its volcanoes.
