page_title: Guallatiri
section_title: Geology
hierarchical_section_title: Guallatiri / Geology
caption_attribution_description: English: Geological map of en:Guallatiri volcano.
context_page_description: Guallatiri is a 6,071-metre high volcano in Chile. It is located southwest of the Nevados de Quimsachata volcanic group and is sometimes considered to be part of that group. It is a stratovolcano with numerous fumaroles around the summit. The summit may be composed of either a lava dome or a pyroclastic cone, while the lower flanks of the volcano are covered by lava flows and lava domes. The volcano's eruptions have produced mostly dacite along with andesite and rhyolite.
  Guallatiri has been active in historical times with a number of eruptions, the latest in 1960. Fumarolic and seismic activity is ongoing and has resulted in the deposition of sulfur and other minerals on the volcano. The volcano is covered by an ice cap above 5,500 metres elevation. Guallatiri, along with several other volcanoes, is part of Lauca National Park.
context_section_description: Guallatiri is a 6,071 metres (19,918 ft) high complex volcano formed mainly by lava flows but also featuring dacitic or andesitic lava domes, such as Domo Tinto on the southern flank. The volcano is 19.3 kilometres (12.0 mi) wide and 1,700-metre-high (5,600 ft) above the basement rocks. The total volume of the volcano cannot be known with certainty, as it varies, but it amounts to between 40-86 cubic kilometers. The volcano's foot covers a surface of about 292 square kilometres (113 sq mi). The summit is formed by a pyroclastic cone; alternative interpretations see it as a lava dome or a hydrothermally altered, scree-covered lava plug. The vent lies south of the summit and the summit crater is breached westwards and northwards. 
  Lava flows radiate from the summit and lava domes dot its flanks. Some lava flows are up to 7 kilometres (4.3 mi) long and 100 metres (330 ft) high and thick lava flows are particularly noticeable on the western and northern slope of the volcano. "Breadcrust" lava bombs are found on the northern flanks, probably carried there by glaciers. Other eruption products include ash flows and tephra layers. The former are particularly developed on the south-southwest flank and the tephras particularly on the southern-eastern flanks.
  Guallatiri is underpinned by the rocks of the Lauca Formation, which has an age of 10–0.5 million years. An older basement domain known as the Lupica Formation is exposed north, west and south of the volcano and contains sediments and volcanic rocks. It is of Oligocene-Miocene age. Like other volcanoes in the area, it formed on top of the Chilean Altiplano.
  Guallatiri may have formed during the Pliocene, with a second stage of volcanic activity recommencing during the Pleistocene; the volcano started forming about 710,000 years ago. Two stages of volcanic activity in the Pleistocene-Holocene have been identified, although a three-stage chronology of volcanic activity has been proposed as well; this proposal envisages two earlier lavic stages and a third stage characterized by the emission of pyroclastics and lava domes. Volcanic activity in the Quimsachata volcanic chain migrated south from the now deeply eroded Acotango and Humarata volcano to the more recent Capurata and Guallatiri volcanoes. There is evidence indicating that lava flows forming Stage I of volcanic activity were erupted during the middle Pleistocene and the lava domes forming Stage II were erupted in the Pleistocene-Holocene. The lava bombs on the northern flank suggest that eruptions which produced small amounts of rocks occurred in recent times.
caption: Geological map of Guallatiri
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