Nevado Anallajsi is a
stratovolcano
A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...
in
Bolivia
Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...
. The date of its last eruption is unknown, but its youngest lava flows appear to have erupted from a vent on the north flank of the mountain. The main composition of the volcano is
andesitic
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 predomina ...
and
dacitic
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. ...
. It overlies a plateau which is composed of
ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...
. The volcano covers an area of and is 10.2
mya old based on its erosion state,
while other estimates indicate an age of 2.6 mya.
See also
*
List of volcanoes in Bolivia
The country of Bolivia hosts numerous activeIn vulcanology and this article active volcanoes are those with Holocene eruption, that means eruptions in the last 10,000 years. and extinct volcanoes across its territory. The active volcanoes are i ...
References
Sources
*
Stratovolcanoes of Bolivia
Subduction volcanoes
Polygenetic volcanoes
Volcanoes of La Paz Department (Bolivia)
Five-thousanders of the Andes
Pleistocene stratovolcanoes
{{LaPazBO-geo-stub