Guallatiri

Guallatiri is a 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 but a large prehistorical eruption took place 2,600 years ago. 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 elevation that has shrunk and fragmented during the course of the 20th-21st century. Guallatiri, along with several other volcanoes, is part of Lauca National Park and is monitored by SERNAGEOMIN.

Name and first ascent

The term means "abundance of the Andean goose" in Aymara and refers to its frequent occurrence in the area. Other names are Punata which is also Aymara, Huallatiri and Huallatire. It was first climbed by the German-Bolivian geologist in 1926.

Geography and geomorphology

The volcano lies in the Putre municipality in the Arica and Parinacota Region. It is located south of Lake Chungara
and west of Cerro Capurata. The latter is part of the Nevados de Quimsachata volcano chain which also includes Humurata and Acotango; sometimes Guallatiri is considered to be part of the Nevados de Quimsachata. Guallatiri is part of the larger Western Cordillera which is the western boundary of the Altiplano high plateau.

The small town of Guallatiri is southwest of the volcano and is the settlement closest to it; it features a cemetery, a 17th-century church and a refuge of the National Forest Corporation. Other towns include Ancuta, Carbonire and Churiguaya. each had a population of less than 25 people. The provincial capital Putre is north of the volcano, and farther west Arica lies on the Pacific Ocean. Economic activity in the area include the Tambo Quemado border crossing, agriculture, animal husbandry as well as tourism and mountaineering, including ascents to the summit of Guallatiri. The frontier between Bolivia and Chile runs along the Nevados de Quimsachata northeast of Guallatiri and is not far from the volcano. The volcano is remote and thus poorly known.

The volcano

Guallatiri is , or high. It is a composite volcano or stratovolcano with a symmetric cone surmounted by a lava dome or lava complex and a vent just south of it. The summit area has also been interpreted as an eroded volcanic plug or as a lava dome.

Lava domes, lava flows, tephra and volcanic ash make up the volcano. Guallatiri rises about above the surrounding terrain and covers a surface of about ; the total volume is about . Thick lava flows emanate in all directions but are primarily noted on the northern and western flanks and reach lengths of . The lava flows have a lobate appearance even when they are heavily eroded, and displays levees, ogives, polygonal cracks and blocky surfaces. Older flows have been eroded into hills. They reach thicknesses of . Fans of block-and-ash flows occur on the southern and southwestern flanks. Tephra deposits are mainly located on the eastern and southern side of Guallatiri. Tuffs and pyroclastic flow deposits occur both in the summit region and in radial valleys that emanate from Guallatiri although some of the latter have been reinterpreted as being reworked sediments.
Apart from volcanic rocks, glacial deposits cover large parts of the volcano and there are traces of mass failures.

On the southern flank, there are two lava domes named Domo Tinto and Domo Sur; other than these Guallatiri has no lateral vents. These domes form a northwest–southeast line and are apart. Domo Tinto is wide and high while Domo Sur is thick and wide. Domo Tinto has a hummocky surface and resembles a pancake.

There are both cold springs and hot springs on Guallatiri, indicating that groundwater interacts with the magmatic system. One hot spring is located at Chiriguaya on the northwestern foot of Guallatiri, where temperatures of were measured in bubbling pools and sinter deposition takes place. Several streams run off the mountain; they eventually enter Lake Chungara and the Rio Lauca.

Ice

Above - elevation the volcano is covered with ice. , a small ice cap on Guallatiri covered an area of with of ice. Ice area has been retreating at a rate of , leading to the breakup of the ice cap in several separate ice bodies. Heat emitted by fumaroles may have contributed to the enhanced melting of the ice.

Glacial deposits on Guallatiri cover an area of about above elevation, with lateral moraines reaching lengths of and thicknesses of . Unlike the global last glacial maximum which peaked between 21,000 and 19,000 years ago, in the area of Guallatiri glaciers reached their maximum extent between 13,500 and 8,900 years ago. This is a consequence of the climate in the region, where glacier extent was more sensitive to increased moisture supply than to decreasing temperatures. Some glaciers were still present during the Holocene, as the Domo Tinto lava dome bears traces of glacial erosion and is partially covered by moraines.

Volcanic units overlie glacial deposits, or inversely glacial deposits such as various types of moraines overlie older volcanic rocks. Older volcanic rocks bear glacial striations and volcanic bombs on the lower flanks may have been transported there by glaciers.

Geology

Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of about . The subduction process is responsible for the volcanism of the Northern Volcanic Zone (NVZ), Central Volcanic Zone (CVZ) and Southern Volcanic Zone (SVZ) and has also driven the formation of the Altiplano during the last 25 million years.

The CVZ is a long chain of volcanoes spanning southern Peru, northern Chile, western Bolivia and northwestern Argentina. It contains about 58 volcanoes which are potentially active or active, 33 of which are located within Chile. The most active of these is Lascar, which in 1993 produced the largest historical eruption of northern Chile.

Guallatiri rises above Oligocene to Pliocene