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Uturunku
Uturunku (Quechua for jaguar, hispanicized spellings ''Uturunco, Uturuncu'') is a volcano in the Cordillera de Lípez in Potosí Department, Bolivia. It is located in the Sur Lípez Province, San Pablo de Lípez Municipality. It is in the Central Volcanic Zone of the Andes, and its summit is above sea level. The volcano has two summits, with a fumarole field between them. The volcano's landforms include lava domes and lava flows.
The volcano was sporadically active during the Pleistocene, with the most recent eruption dated at 271,000 years ago. Since then, Uturunku has displayed fumarolic activity. Starting in 1992 satellite observations have indicated a large area of regional uplift centered on Uturunku, which has been interpreted as an indication of large-scale magma intrusion under the volcano. This might be a prelude to large-scale volcanic activity, including "supervolcanic" activity and caldera formation.
==Geography and geology==
Uturunku is a dormant stratovolcano south of Quetena Chico, in the Altiplano of Bolivia. The edifice has a volume of , covering an area of assuming a base of . It is constructed from porphyritic dacite lava flows with some andesitic flows and domes covered by prismatically jointed blocks. The edifice has been affected by glacial activity. The Lower and Middle Pleistocene lava flows form the base of the edifice and extend away from the volcano. Middle and Upper Pleistocene lavas form the upper part of the volcanoes and extend up to away. Longer lava flows originated from the central vent, while other flows are only a few kilometres long. Flow features on the lavas are well preserved, and are blocky with high fronts. The flows are between thick. Forty–five lava flows and ten lava domes have been identified. Lava domes are found on the flank of the volcano, while lava flows cannot be traced back to the flank vents.〔〔 A sulfur mine () was reported in 1975. It was based on native sulfur and minor realgar in the volcanic ash, with an estimated 50 million tonnes of ore. Laguna Celeste lies at the foot of the volcano and is fed by snow melt from the volcano's northeastern side. Mama Khumu, a lake on the western side of the volcano, is also fed from it.〔
Uturunku's lavas contain biotite,〔 hypersthene,〔 ilmenite, magnetite, orthopyroxene and plagioclase. They also contain inclusions, a few percent andesite, norite and xenoliths derived from the crust containing sillimanite gneiss and igneous rocks. Morphological and chemical analysis of the eruption products indicate that the dacites formed by fractional crystallization of andesite magma. Some of the dacite magma was modified by mixing of dacite and andesite magmas. The magma also underwent oxidation and degassing during ascent.〔 Analysis of the erupted dacites indicate that the magma was nearly water-saturated and stored at depths of 〔 or 〔 and temperatures of . The chemistry and microstructure suggest that Uturunku magmas formed in magma chambers subject to episodic replenishment with hotter magmas.〔〔 Major and trace element analysis indicates a substantial similarity of Uturunku lavas to local ignimbrites.〔
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