Lanín is an ice-clad, cone-shaped

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 ...

on the border of

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

and

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. It forms part of two

national park A national park is a nature park designated for conservation (ethic), conservation purposes because of unparalleled national natural, historic, or cultural significance. It is an area of natural, semi-natural, or developed land that is protecte ...

s: Lanín in Argentina and Villarrica in Chile. As a part of the flag and anthem of the Argentine province of Neuquén, it serves as a symbol for the region. Although the date of its last eruption is not known, it is estimated to have occurred within the last 10,000 years. Following the

1906 Valparaíso earthquake The 1906 Valparaíso earthquake hit Valparaíso, Chile, on August 16 at 19:55 local time. Its epicenter was offshore from the Valparaíso Region, and its magnitude was estimated at 8.2 . This earthquake occurred thirty minutes after the 1906 ...

a local newspaper reported the volcano to have erupted, but a work published in 1917 by Karl Sapper disputed this.Luis E. Lara, José A. Naranjo and Hugo Moreno, 2004
Lanín volcano (39.5°S), Southern Andes: geology and morphostructural evolution
'' Revista Geológica de Chile'' vol. 31. The ascent is regulated by the management of Argentine National Parks and the Argentine National Gendarmerie and is technically relatively simple but has a much higher level of exposure than the neighbouring volcanoes. The nearest towns, usually employed as a base for climbers, are Pucón in Chile and Junín de los Andes in Argentina. There are two paths to the summit: one on the north, starting at 1,200 metres above mean sea level near Tromen Lake and the international Mamuil Malal Pass, accessible via Neuquén's Provincial Route 60; and one on the south, starting beside Huechulafquen Lake, accessible via Provincial Route 61.

Geography and geology

Lanín lies at the Atlantic-Pacific water divide of the Andes, being for that reason located on the Argentina-Chile border according to the 1881 border treaty between these countries. To the north and south lie the Tromen and Paimun Lakes, respectively. Lanín is the easternmost volcano of a north-west south-east oriented chain of three large

es, Villarrica being the westernmost one and Quetrupillán the one in the middle. This alignment is attributed to the existence of a fault beneath the volcanoes. In historical times, Lanín has been the least active of these volcanoes. Apart from Quetrupillán and Villarrica, there are a number of old eroded remains of stratovolcanoes in the alignment. The volcano itself rests on a basement of

gneiss Gneiss (pronounced ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under p ...

es,

felsic In geology, felsic is a grammatical modifier, modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted ...

pluton In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s, and volcani

clast Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks b ...

ic sequences. The basement rocks constitute a tectonically elevated block limited in the west by the north–south Reigolil-Pirihueico Fault. Ages of ranging from Late

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

have been suggested for the oldest known parts of the volcano, which are dacitic

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

s with columnar joints.

Basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

is the most common rock of the volcano. Lanín shows overall higher alkali (Na₂O plus K₂O) to silica ratio than Villarrica, which is interpreted as reflecting a lesser degree of

partial melting Partial melting is the phenomenon that occurs when a rock is subjected to temperatures high enough to cause certain minerals to melt, but not all of them. Partial melting is an important part of the formation of all igneous rocks and some metamorp ...

underneath the volcano and showing that the volcanoes of the chain have distinct source regions in Earth's mantle. Another

petrologic Petrology () is the branch of geology that studies rock (geology), rocks, their mineralogy, composition, texture, structure and the conditions under which they form. Petrology has three subdivisions: igneous petrology, igneous, metamorphic rock, ...

characteristic of Lanín is its bimodal volcanism.

References

External links

*
La estrella del Parque: el Volcán Lanín
- San Martín de los Andes municipal website. {{DEFAULTSORT:Lanin Stratovolcanoes of Chile Subduction volcanoes Stratovolcanoes of Argentina Villarrica National Park Volcanoes of Araucanía Region Volcanoes of Neuquén Province Argentina–Chile border International mountains of South America Three-thousanders of the Andes Pliocene stratovolcanoes Pleistocene stratovolcanoes Holocene stratovolcanoes

Geography and geology

See also

References

External links