Huequi () is a

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

in the

Los Lagos Region Los Lagos Region ( , 'Region of the Lakes') is one of regions of Chile, Chile's 16 regions, which are first order administrative divisions, and comprises four provinces: Chiloé Province, Chiloé, Llanquihue Province, Llanquihue, Osorno Provin ...

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 is in 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 America ...

, in the centre of

Ayacara Peninsula Ayacara Peninsula is a peninsula in northwestern Patagonia in Chile that protrudes to the northwest. The peninsula bounds to the southwest with Reñihué Fjord and to the northeast with Comau Fjord. The volcano Huequi lies in the central parts of th ...

and close to the

Gulf of Ancud 250px, Map of the Sea of Chiloé and nearby roads. The Gulf of Ancud is seen in the centre of the upper half. Gulf of Ancud () is a large body of water separating the Chiloé Island from the mainland of Chile. It is located north of the Gulf of C ...

. It is made up of a lava dome complex situated in a depression of unclear origin, a postglacial lava dome Calle and a

Pleistocene 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 ...

volcano with Holocene parasitic cones, with a sharp summit at . There were reports of eruptions 1890–1920, and it is said to have "smoked" in 1935.

Geography and geology

The volcano is also known as Hueque, Relibuentu and Huequen. It is in a remote region of southern Chile with no road access. There are only a few villages along the coast, and little human modification of the environment. Huequi lies roughly at the centre of the

east of the

. Huequi is part of the

(SVZ), lying in its southern sector between the volcanoes Hornopiren and Chaiten- Minchinmavida; Chaiten erupted in 2008. Compared to other volcanoes in the SVZ it is small, rising only from a curved depression to an elevation of , and it lacks

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

s. Huequi consists of a pile 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 ...

s that are heavily eroded and cut by

sector collapse A sector collapse or lateral collapse is the structural failure and subsequent collapse of a minimum volume of of a volcano. Unlike smaller flank collapses, a sector collapse can involve the central volcanic pipe and historically this term had b ...

s. A partially collapsed dome forms the summit. A

summit crater A volcanic crater is an approximately circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature containing one or more vents. During volcanic eruptions, molten magma and volcanic gases rise from an und ...

was reported as "narrow" in 1909 and as wide by the

Global Volcanism Program The Smithsonian Institution's Global Volcanism Program (GVP) documents Earth's volcanoes and their eruptive history during the Quaternary Period of Earth's geologic history, with particular emphasis on volcanic activity during the Holocene Epoc ...

Debris avalanche Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock flow down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally ...

s, partly channelled by a northwestward trending valley in the edifice, have formed a fan on that side of Huequi.

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

from the volcano has been carried to the sea by the Huequi River, which originates at the foot of Huequi. Two additional cones are named Porcelana and Barranes Colorado or Barranco Colorado; there is also the Calle

postglacial The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

lava dome. The Huequi volcano may be part of larger volcanic complexes that are now eroded. The

basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...

is formed by faulted

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

and

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, caus ...

s of the

North Patagonian Batholith The North Patagonian Batholith () is a series of igneous plutons in the Patagonian Andes of Argentina and Chile. Geology The Northern Patagonian Batholith was formed in the Mesozoic Era and Cenozoic Era. It is made up of a collection of individu ...

. The

subduction Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...

of the

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

under 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 ...

gives rise to the volcanism of the Andes. In the southern sector between

Yate Yate is a town and civil parish in South Gloucestershire, England. It lies just to the southwest of the Cotswolds, Cotswold Hills and is northeast of Bristol and from Bath, Somerset, Bath. Developing from a small village into a town from t ...

and Cerro Hudson, where Huequi is located, the crust is thin and does not heavily influence the

basaltic Basalt (; ) is an 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 surface of a rocky planet or moon. More than 90% ...

and

basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Ameri ...

magmas. East of the volcano passes the Liquine-Ofqui Fault Zone in a

fjord In physical geography, a fjord (also spelled fiord in New Zealand English; ) is a long, narrow sea inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Antarctica, the Arctic, and surrounding landmasses of the n ...

; the volcano lies on a separate, northwest-trending

lineament ''See also Line (geometry)'' A lineament is a linear feature in a landscape which is an expression of an underlying geological structure such as a fault. Typically a lineament will appear as a fault-aligned valley, a series of fault or fold-align ...

Composition

Huequi has erupted

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 predomina ...

and

, which have grey and red colours and feature both layered and

breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...

ted sequences.

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. ...

has also been reported. The volcanic rocks define a

calc-alkaline The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic ...

suite that resembles the adakites of Nevado de Longavi. The main

phenocryst image:montblanc granite phenocrysts.JPG, 300px, Granites often have large feldspar, feldspathic phenocrysts. This granite, from the Switzerland, Swiss side of the Mont Blanc massif, has large white phenocrysts of plagioclase (that have trapezoid sh ...

phase is

plagioclase Plagioclase ( ) is a series of Silicate minerals#Tectosilicates, tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continu ...

, followed by

orthopyroxene The pyroxenes (commonly abbreviated 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 ions of calcium (Ca), sodium (Na), iron (Fe( ...

and

hornblende Hornblende is a complex silicate minerals#Inosilicates, 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 ...

. The lava domes contain columnar forms exposed in cliffs and dense porphyries. Compared to other volcanoes in this sector of the Southern Volcanic Zone, Huequi's magmas are water-rich. This may explain some peculiarities about its eruptive activity, as the water escapes from the magma and leaves a viscous andesite.

Climate and vegetation

The region has a humid climate, with storm systems from the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

bringing about or of precipitation during autumn and winter. Mean annual temperatures are about . It is covered by the Valdivian rainforest, with ''

Amomyrtus meli ''Amomyrtus meli'', known as meli, is a species of tree in the family Myrtaceae. It is endemic to Chile and grows from Arauco to Chiloe (37 to 42°S). It grows mostly on moist and shaded sites. Description It is an evergreen tree that measure ...

'', ''

Drimys winteri ''Drimys winteri'', also known as Winter's bark, foye and canelo, is a slender species of tree in the family Winteraceae, growing up to tall. It is native to the Magellanic and Valdivian temperate forests of Chile and Argentina, where it is a ...

'', ''

Luma apiculata ''Luma apiculata'', the Chilean myrtle, ''arrayán'' or ''temu'', is a species of flowering plant in the myrtle family, native to the central Andes between Chile and Argentina, at 33 to 45° south latitude. Growing to tall and wide, it is a vigo ...

'', ''

Nothofagus nitida ''Nothofagus nitida'' (Chiloé's coigue) is an evergreen tree, native to southern Chile and Argentina. It is found from latitude 40° S to Última Esperanza ( 53° S). Description Up to 35 m (115 ft) height and 2 m (6.5 ft ...

'' and ''

Podocarpus ''Podocarpus'' () is a genus of conifers, the most numerous and widely distributed of the podocarp family, the Podocarpaceae. ''Podocarpus'' species are evergreen shrubs or trees, usually from tall, known to reach at times. The cones have ...

'' as representative plant species.

Eruption history

Southeast of Huequi lie three small volcanoes, which probably erupted during the

. Porcelana is of Pleistocene age. During the

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

, the volcano repeatedly produced

s that frequently collapsed, and

explosive eruption In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a Viscosity, viscous ...

s that deposited

tephra Tephra is fragmental material produced by a Volcano, 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, ...

. The debris avalanche deposits consist of older volcanic rocks,

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

and

lithics Lithic may refer to: *Relating to stone tools ** Lithic analysis, the analysis of stone tools and other chipped stone artifacts ** Lithic core, the part of a stone which has had flakes removed from it ** Lithic flake, the portion of a rock removed ...

from the basement. The collapses were not energetic, with most of the debris being confined by the surrounding topography; their heavy vegetation cover indicates that they are older than the most recent eruption.

Tephra Tephra is fragmental material produced by a Volcano, 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, ...

layers in Lago Futalaufquen have been correlated to an eruption in AD 1645–1745. There are sparse reports of eruptions between 1890–1920, with reports from the years 1890–91, 1893–94, 1895–96, 1906, 1917, 1920, and 1922. The activity was visible from Chiloe and

Puerto Montt Puerto Montt (Mapuche: Meli Pulli) is a port city and commune in southern Chile, located at the northern end of the Reloncaví Sound in the Llanquihue Province, Los Lagos Region, 1,055 km to the south of the capital, Santiago. The commune ...

. Some of this activity may relate to 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 ...

. These eruptions reached a

volcanic explosivity index The volcanic explosivity index (VEI) is a scale used to measure the size of explosive volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982. Volume of products, eruption c ...

of 2–3 and deposited patches of

to the north of the volcano. Contemporary records indicate that the 1890 eruption deposited ash from Chiloe into Argentina. The tephra consists of red and black

scoria Scoria or cinder is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackso ...

and

, formed presumably by

Vulcanian eruption A Vulcanian eruption is a type of volcanic eruption characterized by a dense cloud of ash-laden gas exploding from the crater and rising high above the peak. They usually commence with phreatomagmatic eruptions which can be extremely noisy due t ...

s. The summit dome may have formed during this sequence. The volcano was reportedly "smoking" in 1935. Porcelana

geyser A geyser (, ) is a spring with an intermittent water discharge ejected turbulently and accompanied by steam. The formation of geysers is fairly rare and is caused by particular hydrogeological conditions that exist only in a few places on Ea ...

and Porcelana

hot spring A hot spring, hydrothermal spring, or geothermal spring is a Spring (hydrology), spring produced by the emergence of Geothermal activity, geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow ...

lie on the Ayacara Peninsula and are associated with Huequi. The Porcelana geysers have produced pinnacles of

travertine Travertine ( ) is a form of terrestrial limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and rusty varieties. It is formed by a process ...

reaching heights of ; this extreme size in a highly erosive environment may be due to

microbial A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...

chemical processes. The area has good potential for

geothermal energy Geothermal energy is thermal energy extracted from the crust (geology), crust. It combines energy from the formation of the planet and from radioactive decay. Geothermal energy has been exploited as a source of heat and/or electric power for m ...

References

Sources

* * * * * * * * * * * * * *

External links

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SERNAGEOMIN
{{Andean volcanoes Mountains of Chile Volcanoes of Los Lagos Region Holocene lava domes Lava domes of Chile One-thousanders of the Andes