Aguilera (volcano)
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Aguilera () 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 southern
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 ...
. The volcano rises above the edge of the
Southern Patagonian Ice Field The Southern Patagonian Ice Field (), located at the Southern Patagonic Andes between Chile and Argentina, is the world's second largest contiguous extrapolar ice field. It is the bigger of two remnant parts of the Patagonian Ice Sheet, which c ...
. It is a remote volcano that was identified as such in 1985. The first ascent only occurred in 2014, making it the last unclimbed major Andean volcano. Aguilera is located west of
Lake Argentino Lago Argentino is a lake in the Patagonian province of Santa Cruz, Argentina, at . It is the largest freshwater lake in Argentina, with a surface area of and a maximum width of . The lake's waters have an average depth of , with a maximum depth ...
and northeast of Peel Fjord in the southern
Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...
and erupted mainly
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. ...
s and
pyroclastic Pyroclast, Pyroclastic or Pyroclastics may refer to: Geology * Pyroclast, or airborne volcanic tephra fragments * Pyroclastic rock, rock fragments produced and ejected by explosive volcanic eruptions * Pyroclastic cone, landform of ejecta fro ...
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, ...
. It has erupted several times in 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 ...
, with a major eruption taking place 3,000 ± 1,000 years before present. Its eruptions have spread ashfalls over
Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...
.


Geography and geomorphology

Aguilera lies west of the city of Calafate, northwest of Peel Fjord and within the commune of Natales. There is not much knowledge on volcanism in southernmost Chile/
Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...
as the volcanoes are poorly mapped, difficult to access and the weather conditions hostile. Aguilera was named in 1933 by
Alberto Maria de Agostini Father Alberto Maria de Agostini (2 November 1883 – 25 December 1960) born in Pollone, Piedmont was an Italian missionary of the Salesians of Don Bosco order as well as a passionate Mountaineering, mountaineer, explorer, geographer, ethnographe ...
, so its volcanic nature was first established in 1985. Aguilera is part of the Andean
Austral 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 Americ ...
, which lies in the southernmost territory of Chile. It consists of six volcanoes, from north to south these are
Lautaro Lautaro (Anglicized as 'Levtaru') ( " swift hawk") (; 1534 – April 29, 1557) was a young Mapuche toqui known for leading the indigenous resistance against Spanish conquest in Chile and developing the tactics that would continue to be empl ...
, Viedma, Aguilera, Reclus,
Monte Burney Monte Burney is a volcano in southern Chile, part of its Austral Volcanic Zone which consists of six volcanoes with activity during the Quaternary. This volcanism is linked to the subduction of the Antarctic Plate beneath the South American Plat ...
and
Cook Cook or The Cook may refer to: Food preparation * Cooking, the preparation of food * Cook (domestic worker), a household staff member who prepares food * Cook (profession), an individual who prepares food for consumption in the food industry * C ...
; only the first has clearly documented historical activity, in 1959–1960. The first five are located on the South America Plate at increasing distances from the
trench A trench is a type of digging, excavation or depression in the ground that is generally deeper than it is wide (as opposed to a swale (landform), swale or a bar ditch), and narrow compared with its length (as opposed to a simple hole or trapping ...
, while Cook is on the Scotia Plate and is a complex 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 unlike the other volcanoes which are
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 ...
es. North of Lautaro lies a long gap without volcanism and then Cerro Hudson, the southernmost volcano of 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 ...
. The volcano is a or high
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 ...
that rises from the
Southern Patagonian Ice Field The Southern Patagonian Ice Field (), located at the Southern Patagonic Andes between Chile and Argentina, is the world's second largest contiguous extrapolar ice field. It is the bigger of two remnant parts of the Patagonian Ice Sheet, which c ...
, reaching a height of about above its base and almost entirely covered with ice.


Geology

Off southwesternmost South America, the Antarctic Plate
subducts 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 pla ...
beneath the
South America 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- ...
at a rate of . This subduction is responsible for the volcanism in the Austral Volcanic Zone, whereas
earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...
activity is low; this is possibly because the subducting plate is too hot and too slow moving. 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, ...
below Aguilera is of
Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...
-early
Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...
age and consists of
metamorphic 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, causi ...
rocks. The volcano sits at the easterly margin of the Patagonian Batholith, a
Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...
-
Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...
igneous Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...
rock province. Volcanism occurs along much of the Andes, partly due to the subduction of the Antarctic Plate and partly due to the subduction 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– ...
, in each case beneath the South America Plate. The latter subduction gives rise to the
Northern 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 ...
, the
Central 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 Americ ...
and 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 ...
of the Andes. The
Austral 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 Americ ...
was once considered part of the Southern Volcanic Zone.


Composition

Aguilera has erupted
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. ...
s with intermediate contents of
potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...
, defining 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 with adakitic characteristics.
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 ...
s include
amphibole Amphibole ( ) is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is ...
,
biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron- endmember annite, and the magnesium-endmember phlogopite; more al ...
,
clinopyroxene 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 ...
,
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 ...
and
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 ...
; plagioclase and also
orthoclase Orthoclase, or orthoclase feldspar ( endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture", because its two cleavage planes are at right angles ...
and
pyroxene 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 ( ...
often occur as
xenolith A xenolith ("foreign rock") is a rock (geology), rock fragment (Country rock (geology), country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusi ...
s. Melts of subducted sediment and from the subducting
slab Slab or SLAB may refer to: Physical materials * Concrete slab, a flat concrete plate used in construction * Stone slab, a flat stone used in construction * Slab (casting), a length of metal * Slab (geology), that portion of a tectonic plate that ...
give rise to the magmas of Aguilera and other volcanoes of the northern Austral Volcanic Zone, but they are subsequently modified by interactions with the
mantle wedge A mantle wedge is a triangular shaped piece of mantle that lies above a subducting tectonic plate and below the overriding plate. This piece of mantle can be identified using seismic velocity imaging as well as earthquake maps. Subducting oceanic ...
and in the case of Aguilera, Lautaro and Viedma, further interaction takes place with the
Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...
crust.


Climate and vegetation

Aguilera lies within the Southern Hemisphere
Westerlies The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes (about ...
belt and the average temperature of the region is about . There is a west-east precipitation gradient from to less than in the region; frontal systems and cyclones within the westerlies deliver most precipitation in the region, but precipitation rates are controlled by
orographic precipitation Orography is the study of the topographic relief of mountains, and can more broadly include hills, and any part of a region's elevated terrain. Orography (also known as ''oreography'', ''orology,'' or ''oreology'') falls within the broader disci ...
and the
rainshadow effect A rain shadow is an area of significantly reduced rainfall behind a mountainous region, on the side facing away from prevailing winds, known as its leeward side. Evaporated moisture from body of water, bodies of water (such as oceans and larg ...
resulting in the west-east gradient. Vegetation in the region ranges from
Magellanic subpolar forests The Magellanic subpolar forests () are a terrestrial ecoregion of southernmost South America, covering parts of southern Chile and Argentina, and are part of the Neotropical realm. It is a temperate broadleaf and mixed forests ecoregion, and ...
to
semidesert A semi-arid climate, semi-desert climate, or steppe climate is a dry climate sub-type. It is located on regions that receive precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of sem ...
, depending on the amount of moisture available; ''
Nothofagus ''Nothofagus'', also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere, found across southern South America (Chile, Argentina) and east and southeast Australia, New Zealand, New Guin ...
'' species form most of the woods, including ''
Nothofagus antarctica ''Nothofagus antarctica'' (''Antarctic beech''; in Spanish ''Ñire'' or ''Ñirre'') is a deciduous tree or shrub native to southern Chile and Argentina from about 36°S to Tierra del Fuego (56° S), where it grows mainly in the diminishing tempe ...
'', ''
Nothofagus betuloides ''Nothofagus betuloides'', Magellan's beech or ''guindo'', is a tree native to southern Patagonia. In 1769, Joseph Banks, Sir Joseph Banks collected a botanical specimen, specimen of the tree in Tierra del Fuego during James Cook, Captain Cook's ...
'' and ''
Nothofagus pumilio ''Nothofagus pumilio'', the lenga beech (from the Mapuche language), is a deciduous tree or shrub in the Nothofagaceae family that is native to the southern Andes range, in the temperate forests of Chile and Argentina to Tierra del Fuego, from 35 ...
''.


Eruption history

Aguilera erupted 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 ...
, depositing tephra in the region of
Lago Argentino Lago Argentino is a lake in the Patagonian province of Santa Cruz, Argentina, at . It is the largest freshwater lake in Argentina, with a surface area of and a maximum width of . The lake's waters have an average depth of , with a maximum depth ...
and
Torres del Paine The Cordillera Paine is a mountain group in Torres del Paine National Park in Chilean Patagonia. The cordillera is located north of Punta Arenas, and about south of the Chilean capital Santiago. It belongs to the Commune of Torres del Paine ...
. The composition of rocks erupted by Aguilera are similar to these from Lautaro and Viedma, and the linkage of specific ash deposits to Aguilera is based mainly on geographical considerations. Other volcanoes have left tephra deposits in the wider region, including Cerro Hudson, Monte Burney and Reclus. Evidence of possible eruptions at Aguilera include a 42,400 - 51,747 years old thick tephra from Laguna Potrok Aike, two ash layers emplaced 5,700 and 5,150 years before present in the Vega Ñandú
mire A peatland is a type of wetland whose soils consist of Soil organic matter, organic matter from decaying plants, forming layers of peat. Peatlands arise because of incomplete decomposition of organic matter, usually litter from vegetation, du ...
in
Torres del Paine National Park Torres del Paine National Park () is a national park encompassing mountains, glaciers, lakes, and rivers in southern Chilean Patagonia. The Cordillera del Paine is the park's centerpiece. It lies in a transition area between the Magellanic subpo ...
, and a 5,500 years old tephra layer at various sites in and around Peninsula Avellaneda. A tephra layer found at archeological sites around
Lago Argentino Lago Argentino is a lake in the Patagonian province of Santa Cruz, Argentina, at . It is the largest freshwater lake in Argentina, with a surface area of and a maximum width of . The lake's waters have an average depth of , with a maximum depth ...
and deposited there 4,091 - 4,566 years before present originated at Aguilera and probably disrupted local human communities. Farther away in
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
, a tephra found in Talos Dome and deposited there 4,420 years before present may have originated at this volcano as well. Another smaller eruption occurred at Aguilera after the A1 event and deposited ash in the
Lago Argentino Lago Argentino is a lake in the Patagonian province of Santa Cruz, Argentina, at . It is the largest freshwater lake in Argentina, with a surface area of and a maximum width of . The lake's waters have an average depth of , with a maximum depth ...
area; the date of its eruption is unknown. There are no known historical eruptions although an eruption reported in 1886 in the area may have occurred at Aguilera.


A1 eruption

The major A1 eruption occurred at Aguilera or years ago. It deposited tephra east of the volcano as far south as the
Strait of Magellan The Strait of Magellan (), also called the Straits of Magellan, is a navigable sea route in southern Chile separating mainland South America to the north and the Tierra del Fuego archipelago to the south. Considered the most important natura ...
; other Aguilera tephras are less widespread. Its volume has been estimated to be between , larger than the 1991 eruption of Cerro Hudson, reaching level 5 on the
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 ...
. Tephra deposits from this eruption have been found in the Cordillera Baguales ( thickness), at
Gran Campo Nevado The Gran Campo Nevado is a small ice field located in the southern portion of the Muñoz Gamero Peninsula, in Chile. It covers an area of approximately and feeds 19 outlet glaciers, the largest of which is long. See also * Monte Burney *Riesco ...
( thickness),
Lago Argentino Lago Argentino is a lake in the Patagonian province of Santa Cruz, Argentina, at . It is the largest freshwater lake in Argentina, with a surface area of and a maximum width of . The lake's waters have an average depth of , with a maximum depth ...
( thickness), Lago Cardiel ( thickness), Lago Roca ( thickness),
Lake Viedma Viedma Lake (, ) is a Patagonian lake in the province of Santa Cruz, Argentina, situated near its border with Chile. Measuring approximately 50 miles (80 kilometers) in length, it is a major elongated trough lake formed from melting glacial ice. ...
( thickness),
Brunswick Peninsula Brunswick Peninsula () is a large peninsula in Magallanes y la Antártica Region, Patagonia, Chile, at . Geography The Brunswick Peninsula is triangular in shape, joined to the mainland in the north by a wide isthmus. It widens to almost in t ...
( thickness), Seno Skyring (),
Torres del Paine National Park Torres del Paine National Park () is a national park encompassing mountains, glaciers, lakes, and rivers in southern Chilean Patagonia. The Cordillera del Paine is the park's centerpiece. It lies in a transition area between the Magellanic subpo ...
( thickness) and
Isla Grande de Tierra del Fuego Isla Grande de Tierra del Fuego ( English: ''Big Island of the Land of Fire'') also formerly ''Isla de Xátiva'' is an island near the southern tip of South America from which it is separated by the Strait of Magellan. The western portion (61. ...
( thickness). On Isla Grande de Tierra del Fuego apparently the eruption did not substantially impact human populations. Chemicals derived from Aguilera tephra are found in cave deposits close to Monte Burney. Furthermore, a 3,600 years old
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
-rich layer in
ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain 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 ...
s from Talos Dome,
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
, may have been produced by the Aguilera eruption.


First climb

Aguilera was the last major volcano in the Andes to be climbed, with the first successful attempt occurring in August 2014 by a group of Chilean climbers.


References


Sources

* * * * * * * {{Andean volcanoes Volcanoes of Magallanes Region Andean Volcanic Belt Stratovolcanoes of Chile Calderas of Chile Mountains of Magallanes Region Mountains of Chile Holocene stratovolcanoes Two-thousanders of the Andes