Quetrupillán ("blunted", "mutilated"; also known as Ketropillán) is a

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 in Los Ríos Region of

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. It is situated between Villarrica and

Lanín Lanín is an ice-clad, cone-shaped stratovolcano on the border of Argentina and Chile. It forms part of two national parks: Lanín in Argentina and Villarrica in Chile. It is a symbol of the Argentine province of Neuquén, being part of its flag ...

volcanoes, within

Villarrica National Park Villarrica National Park is located in the Andes, in the La Araucanía and Los Ríos regions of Chile, near Pucón. The centerpiece of the park is a line of three volcanoes stretching transversely to the Andean range: Villarrica, Quetrupillán, ...

. Geologically, Quetrupillán is located in a tectonic basement block between the main traces of Liquiñe-Ofqui Fault (to the west) and

Reigolil-Pirihueico Fault The Reigolil-Pirihueico Fault (Spanish: ''Falla Reigolil-Pirihueico'') is a second-order geological fault located in the Chilean and Argentine Andes. As the name implies, it runs from Pirihueico Lake to Reigolil Valley. Reigolil-Pirihueico Fault ru ...

(to the east). The volcano consists of one

with a summit

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

, and is constructed within a field of smaller centres and a larger caldera. It was active during the late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

; some large eruptions occurred during the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

as well.

Geology and geography

The volcano is situated in the Curarrehue, Pucón and

Panguipulli Panguipulli ( ; Mapudungun for "hill of the puma") is a city and commune in Valdivia Province, southern Chile, administered by the Municipality of Panguipulli. It is located on the western edge of Panguipulli Lake, and is on a moraine in the Chi ...

municipalities A municipality is usually a single administrative division having corporate status and powers of self-government or jurisdiction as granted by national and regional laws to which it is subordinate. The term ''municipality'' may also mean the go ...

of the Cautín and

Valdivia Valdivia (; Mapuche: Ainil) is a city and commune in southern Chile, administered by the Municipality of Valdivia. The city is named after its founder Pedro de Valdivia and is located at the confluence of the Calle-Calle, Valdivia, and Cau-Cau R ...

provinces. Towns close to Quetrupillán are Catripulli, Currarehue and Puesco. It is considered Chile's 21st most dangerous volcano.

Regional

Off the western coast of South America, the

Nazca Plate The Nazca Plate or Nasca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru–Chile Trench, of the Na ...

subducts beneath the

South American Plate The South American Plate is a major tectonic plate which includes the continent of South America as well as a sizable region of the Atlantic Ocean seabed extending eastward to the African Plate, with which it forms the southern part of the Mid-A ...

in the Peru-Chile Trench. As the plate subducts, it releases water into the overlying

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

and causes it to melt, gives rise to the

Southern Volcanic Zone The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca Plate and Antarctic Plate underneath the South American ...

of the Andes. The rate and geometry of subduction has varied over time. During the last six million years, the subduction process has been oblique and as a consequence, the Liquiñe-Ofqui Fault has developed within the

volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc lo ...

and dominates the regional tectonics. Quetrupillán lies on the border between Los Ríos Region and Araucanía Region, in the

. Together with Villarrica and

it forms a northwest-southeast alignment of volcanoes, which coincides with the Mocha-Villarrica

transcurrent fault In geology, a fault is a Fracture (geology), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust (geolo ...

. The Cordillera El Mocho and Quinquilil volcanoes are likewise situated on this alignment, both are deeply eroded composite volcanoes of small dimensions. Other volcanoes in the Southern Volcanic Zone have similar alignments, such as

Nevados de Chillán Nevados de Chillán is a group of stratovolcanoes located in the Andes of Ñuble Region, Central Chile, and is one of the most active volcanoes in the region. It consists of three overlapping peaks, Cerro Blanco (Volcán Nevado) at the northwe ...

and

Puyehue-Cordón Caulle Puyehue (; ) and Cordón Caulle are two coalesced volcanic edifices that form a major mountain massif in Puyehue National Park in the Andes of Ranco Province, in the South of Chile. In volcanology this group is known as the Puyehue-Cordón Cau ...

. In comparison to Villarrica, Quetrupillán has been less active and its eruptions were also smaller than Villarrica's, with no large

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...

s found at Quetrupillán.

Local

Quetrupillán is a high composite

and a shrinking

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...

cover; the existence of

s is unconfirmed. The entire edifice has a north-south elongated shape and covers a ground surface of . The volcano contains a field of

lava dome In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on ...

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

s and

pyroclastic cone Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and s ...

s that occupy a surface of . These subsidiary vents include the scoria cone Huililco, the Volcanes de Llancahue and the Volcanoes de Reyehueico. There are in total 16 lateral vents, of which 12 are found in a

volcanic field A volcanic field is an area of Earth's crust that is prone to localized volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters of up to 100 volcanoes ...

south of Quetrupillán.

Fissure vent A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive eruption, explosive activity. The vent is often a few metres wide an ...

s of

age occur on the southern side of the volcano. The small volume of the main Quetrupillán edifice and the widespread vents may reflect the interaction between the volcano and the Liquiñe-Ofqui fault, which generated secondary vents whose location was controlled by the Liquiñe-Ofqui fault, the Mocha-Villarrica fault and local structures. There are two lakes on the southern flank, Laguna Azul to the southwest and Laguna Blanca to the southeast. A number of eruption products show traces of ice-

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

interactions. Tuff rings and maars formed through the interaction of magma with

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

. A

geomagnetic Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic fi ...

anomaly at shallow depth south of the volcano may be a

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 ...

associated with a

resurgent dome In geology, a resurgent dome is a dome formed by swelling or rising of a caldera floor due to movement in the magma chamber beneath it. Unlike a lava dome, a resurgent dome is not formed by the extrusion of highly viscous lava onto the surfac ...

. Huililco

scoria cone Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''G ...

has produced two lava flows and is considered to be also part of the Quetrupillán volcanic complex. Three different

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

s make up the

basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...

of Quetrupillán: The

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

Panguipulli, the possibly

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

Currarehue and the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Trápatrapa formations and

ic rocks. These are plutonic and volcaniclastic rock units. The Villarrica-Quetrupillán volcanic chain forms a geological boundary, since the Patagonian Batholith crops out south of it.

Composition

Volcanic rocks at Quetrupillán have a bimodal composition, ranging from

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 ...

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 overall more silicic than the rocks erupted by Villarrica and Lanín. Unusually for the region, trachydacite also occurs at the volcano. These contain phenocrysts of

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more prope ...

and

pyroxene The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) ...

, with additional microphenocrysts of ilmenite and

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With the ...

. Based on the composition, it has been inferred that the magma reservoir of Quetrupillán contained a mush of crystals, from which magma was repeatedly mobilized following the injection of fresh magmas that reheated the mush.

Fractional crystallization Fractional crystallization may refer to: * Fractional crystallization (chemistry), a process to separate different solutes from a solution * Fractional crystallization (geology) Fractional crystallization, or crystal fractionation, is one of the ...

of basalts generated

trachytic Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and alk ...

melts. A tectonic regime associated with the Liquiñe-Ofqui Fault which prevents magma from simply ascending to the surface may help the magma evolution processes.

Eruptive history

Eruptive activity at Quetrupillán commenced before the

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

s. The first phase of activity involved the formation of calderas and stratovolcanoes; later during the ice ages

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 moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

s and ignimbrites were emplaced. Finally, the present

was emplaced towards the end of glaciation;

parasitic vents A parasitic cone (also adventive cone or satellite cone) is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. It forms from eruptions from fractures on the flank of the volcano. These fractures occur ...

formed even later and produced lava flows. Quetrupillán has erupted

pyroclastic Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...

s, which have formed flow and

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular vol ...

deposits east of the volcano. Several phases of volcanic activity have been inferred from the deposits; most of them feature either

ous or scoriaceous

deposits with varying contents of juvenile

lapilli Lapilli is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range f ...

, lithics and ash fall deposits. * The ''Moraga sequence'' was formed 12,720 ± 40 – 12,690 ± 40 years

Before Present Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becaus ...

(BP) during one rather prolonged eruption. * The ''Puala sequence'' was formed 10,240 ± 40 years BP. * The ''Trancura sequence'' was formed 8,680 ± 40 years BP and has a similar composition to the ''Avutardas sequence''. * The ''Carén sequence'' was formed 3,800 ± 30 years BP. * The ''Correntoso sequence'' was formed 2,930 ± 30 years BP. * The ''Trancas Negras sequence'' was formed 2,060 ± 30 years BP. * The ''Puesco sequence'' was formed 1,650 ± 70 years BP, during the largest known eruption of Quetrupillán. This eruption created a high

eruption column An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption. The volcanic materials form a vertical column or plume that may rise many kilometers into the air a ...

and deposited about of rock. A volcanic explosivity index of 4 has been assigned to this event. * The ''Carén sequence'' was formed 1,380 ± 30 years BP, it is the youngest explosive eruption of Quetrupillán. In addition, three

tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they rem ...

s in neighbouring lakes dated to 16,748–16,189, 15,597–12,582 and 12,708–12,567 years Before Present may originate from Quetrupillán but they have also been attributed to

Sollipulli Sollipulli (; in the Mapuche language) is an ice-filled volcanic caldera and volcanic complex, which lies southeast of the small town of Melipeuco in the La Araucanía Region, Chile. It is part of the Southern Volcanic Zone of the Andes, one o ...

. All these tephras are of

rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

rhyodacitic Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of those plutonic rocks that are intermediate in composition between monzogranite and granodiorite. Rhyodacites form from rapid ...

composition and the eruptions that generated them have an estimated volcanic explosivity index of 3. Reports exist of eruptions during the 19th century, one eruption was reported in 1872. Explosive activity has a recurrence interval of about 1,200 years, which given the age of the last event carries significant implications with regards to the volcanic hazard of Quetrupillán.

Mythology

According to a tale from

Mapuche The Mapuche ( (Mapuche & Spanish: )) are a group of indigenous inhabitants of south-central Chile and southwestern Argentina, including parts of Patagonia. The collective term refers to a wide-ranging ethnicity composed of various groups who sha ...

mythology, originally there were just two volcanoes: Choshuenco and

. Then the volcano ( Villarrica) fought the other two volcanoes in a century-long conflict; eventually Ruka Pillan was victorious, coinciding with the beginning Spanish contest.

Vegetation

, vegetation on Quetrupillán included '' Araucaria araucana'' and '' Nothofagus antarctica'' forests, as well as puna-like vegetation.

References

Sources

* * * * * {{DEFAULTSORT:Quetrupillan Mountains of Chile Stratovolcanoes of Chile Active volcanoes Villarrica National Park Volcanoes of Los Ríos Region Volcanoes of Araucanía Region South Volcanic Zone Mountains of Los Ríos Region VEI-4 volcanoes Pleistocene stratovolcanoes Holocene stratovolcanoes