Aguas Calientes Volcano or Cerro Aguas Calientes, also called Simba, is a cone-shaped
stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
located east of the
Lascar
A lascar was a sailor or militiaman from the Indian subcontinent, Southeast Asia, the Arab world, British Somaliland, or other land east of the Cape of Good Hope, who was employed on European ships from the 16th century until the middle of the 2 ...
volcano and north of
Laguna Lejía
Laguna (Italian and Spanish for lagoon) may refer to:
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, Chile. It is located within a area where the Cordón de Puntas Negras and the Cordón Chalviri volcanic chains intersect. The volcano is constructed from
andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...
and
dacite
Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...
containing
hornblende
Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks ...
and also
anhydrite
Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the ...
and its pyroclastics are all older than Lascar. It has a diameter of about . Some xenoliths of calc-alkaline material are found in Aguas Calientes lavas, and magma mixing has generated lavas containing andesite inclusions in dacites. One eruption of Aguas Calientes postdates the first centre of Lascar and was originally linked to the Lascar Piedras Grandes eruption, before sampling on the deposits of this eruption indicated a relationship with the Lascar volcano itself. Effusion of lava ceased after the cone was built. One summit lava flow may be of Holocene age, but no evidence of historical activity is found (González-Ferrán 1985).
The volcano has been affected by
glaciation
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
. Glacial U-shaped valleys are found on the northern and western flanks, giving the volcano some angular patterns. One valley with glacial features and a subglacial river channel at altitude is found on the northern flank. It extends down to the valley north of Aguas Calientes and intersects the youngest lavas of the volcano.
Aguas Calientes has a well formed summit crater. A small
crater lake
Crater Lake (Klamath language, Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The ...
is found within the Aguas Calientes summit crater, making it one of the highest lakes in the world at an altitude of . The lake has a surface area of and is tinged red from a population of microorganisms. The lake water is acidic and is frequently influenced by activity from Lascar, with winds carrying sulfuric acid and water vapour clouds to the crater lake. Precipitation was measured at with most precipitation falling during the winter months, and strong UV irradiation. The lake has a bacterial ecosystem that is primarily reliant on photosynthesis but may also be influenced by hydrothermal activity from Aguas Calientes volcano. Research has found only limited numbers of bacterial taxa and a large number of DNA sequences that can't be identified as known phylogenetic groups. The lake has been studied as a possible terrestrial analogy to
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...