Cerro Chao

Cerro Chao is a lava flow complex associated with the Cerro del León volcano in the Andes. It is the largest known Quaternary silicic volcano body and part of the most recent phase of activity in the Altiplano–Puna volcanic complex.

Cerro Chao formed over the course of three eruptions preceded by a pyroclastic stage. Three large lobate lava flows erupted in the col between two volcanoes and advanced for a maximum length of 14 kilometres (8.7 mi). The eruption that originated the lava flows probably lasted more than one hundred years and occurred before the Holocene.

Geology

Cerro Chao, also named Cerros de Chao, Chao lava or Chao volcano, is located in the volcanic front of the Central Volcanic Zone of the Andes, between the older Paniri and Cerro del León andesitic stratovolcanoes. The Central Volcanic Zone is one of the three volcanic belts in the Andes.

The region is dominated by the Altiplano–Puna volcanic complex, where during the Miocene–Pleistocene epoch large ignimbrite eruptions occurred. In the present day, volcanism is of andesitic composition forming volcanic cones. Activity is controlled by fault zones, some of these linked to the Pastos Grandes caldera. Neighbouring volcanoes with similar characteristics to Cerro Chao include Cerro Chanca/Pabellon, Cerro Chascon–Runtu Jarita complex, Cerro Chillahuita and La Torta. Cerro Chao lies within a northwest-running belt of volcanoes, some of them over 6,000 metres (20,000 ft) high, of which San Pedro has historical activity. Cerro Chao is the largest such silicic lava flow known.