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Cordón del Azufre is an inactive
complex volcano A complex volcano, also called a compound volcano or a volcanic complex, is a mixed landform consisting of related volcanic centers and their associated lava flows and pyroclastic rock. They may form due to changes in eruptive habit or ...
located in the Central
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 ...
, at 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 consists of three stages of
volcanic cones 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 ...
and associated
lava flows 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 unde ...
, and its activity is a consequence of 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– ...
underneath 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 ...
. North of it are the dormant volcano
Lastarria Lastarria is a high stratovolcano that lies on the border between Chile and Argentina. It is remote, and the surroundings are uninhabited but can be reached through an unpaved road. The volcano is part of the Central Volcanic Zone, one of the ...
and the actively uplifting Lazufre region.


Geography and geology

The volcano, which is sometimes conflated with
Lastarria Lastarria is a high stratovolcano that lies on the border between Chile and Argentina. It is remote, and the surroundings are uninhabited but can be reached through an unpaved road. The volcano is part of the Central Volcanic Zone, one of the ...
, lies at the border between Argentina and Chile and contains a series of
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 and
volcanic 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 ...
s and
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, covering a surface area of . Four craters are aligned in a north–south direction on a
ridge A ridge is a long, narrow, elevated geomorphologic landform, structural feature, or a combination of both separated from the surrounding terrain by steep sides. The sides of a ridge slope away from a narrow top, the crest or ridgecrest, wi ...
, which could reflect a north-south trending lineament. Numerous monogenetic volcanoes and
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 developed on it and buried most of its central crater under lava flows. A pile of lava flows covers an area of on the eastern side. The eastern component is formed by lava flows and craters in Argentina, and the youngest part la Moyra volcano in the western component generated a lava flow that advanced westwards and another that ran to the east. To the north lie the
Plio-Pleistocene The Plio-Pleistocene is an informally described geological pseudo-period, which begins about 5 million years ago (Mya) and, drawing forward, combines the time ranges of the formally defined Pliocene and Pleistocene epochs—marking from about 5&n ...
Atalaya volcano, followed by the
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...
Azufre Oriental and
Lastarria Lastarria is a high stratovolcano that lies on the border between Chile and Argentina. It is remote, and the surroundings are uninhabited but can be reached through an unpaved road. The volcano is part of the Central Volcanic Zone, one of the ...
volcanoes, to the south the Plio-Pleistocene Chuta, the Quaternary Cerro Bayo Complex and the Los Colorados caldera. The area is uninhabited and remote, the climate arid, windy and with high temperature variations. Cordón del Azufre is located east of the Chile Trench, where the subduction takes place. At this latitude, 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 ...
intersects a probably deep-seated structural area named the Archibarca corridor. Around Cordón del Azufre is a more local-scale raised region, as has been observed for some other CVZ volcanoes. The landscape is largely devoid of through-going drainages, as the extreme dryness and the frequent blockages by lava flows prevent its development.


Regional context and composition

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 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– ...
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 ...
. This subduction is responsible for volcanism in the
Andean Volcanic Belt 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 ...
, including the Northern Volcanic Zone, the Central Volcanic Zone (CVZ), the Southern Volcanic Zone and the Austral Volcanic Zone. The CVZ extends over Peru, Bolivia, Chile and Argentina. Volcanic manifestations in the Central Andes include the numerous
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
s and associated
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 ...
s that form the Altiplano-Puna volcanic complex, such as La Pacana and Galán. There are about forty
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...
volcanoes around Cordón del Azufre, which formed on top of
Tertiary Tertiary (from Latin, meaning 'third' or 'of the third degree/order..') may refer to: * Tertiary period, an obsolete geologic period spanning from 66 to 2.6 million years ago * Tertiary (chemistry), a term describing bonding patterns in organic ch ...
volcanic rocks. The region has grown to a high elevation since the
Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
.
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, ...
rocks are
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 ...
volcanic and sedimentary rocks, and the large Pedernales-Arizaro
thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. I ...
runs close to Cordón del Azufre. Volcanic rocks include
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
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. ...
with a
porphyritic Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning ...
appearance 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 ...
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 ...
inclusions. The rocks formed through interactions of ascending basaltic andesite with crustal material. The volcano is noted for its
sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...
deposits, and the source of sulfur in Salar de Gorbea.


Eruption history

Volcanic rocks at Cordón del Azufre are less than one million years old. Activity has moved over time from the north-south craters to the eastern lava flows and vents and eventually to La Moyra. Lava flows of the eastern component have been dated to be 600,000 years old. No activity, including fumarolic activity, has been recorded at Cordón del Azufre, but the appearance (dark and pristine) and radiometric age (0.3 ± 0.3 mya K-Ar on the most recent flow) of the lava flows suggest a recent age with
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 ...
activity. Pyroclastic deposits are linked to the youngest cone may date to a historical eruption. Renewed activity would likely consist of lava flows and pyroclastic deposits and, in light of the total lack of important roads and habitation, potential future eruptions are no threat. It is considered the 21st most dangerous volcano out of 38 in Argentina. Beginning in 1996-1998, an elliptic area of has been uplifting. The centre of the uplifting area is between the volcanoes Lastarria and Cordón del Azufre, and has been named "Lazufre" after the
acronym An acronym is a type of abbreviation consisting of a phrase whose only pronounced elements are the initial letters or initial sounds of words inside that phrase. Acronyms are often spelled with the initial Letter (alphabet), letter of each wor ...
, but Cerro Bayo Gorbea is sometimes included in it. Lastarria, Cordón del Azufre and Cerro Bayo Gorbea form linear fissures that emanate from the centre of the Lazufre uplift, which is surrounded by a ring of Quaternary volcanoes and may be a developing
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
. The start of the uplift may be related to the occurrence of several tectonic earthquakes in the 1990s, such as the 1995 Antofagasta earthquake. They could have perturbed the magma chambers or opened up fractures. Magma influx has been stable . This deformation system is among the largest on Earth, comparable with the size of calderas such as Long Valley and
Yellowstone Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...
. There are several
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 ...
volcanoes around the uplift region, which may be supplied from the sill. Magnetotelluric data show a zone with high
electrical conductivity Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity in ...
that rises from the mantle into the crust, and may be the magma supply to Lazufre. Research published in 2016 indicated that the uplift has been ongoing since at least 400,000 years, based on the deformation of lava flows and volcanoes erupted within this time period. Depending on the highly uncertain estimates for the volume of the magma chamber, a modest overpressure may be sufficient to cause the roof of the chamber to fail and an eruption to start.


See also

* List of volcanoes in Chile *
List of volcanoes in Argentina This is a list of active and extinct volcanoes in Argentina. Volcanoes References

{{Andean volcanoes, state=collapsed Volcanoes of Argentina, Lists of landforms of Argentina, Volcanoes Lists of volcanoes, Argentina Andean Vol ...
* Los Colorados (caldera)


References


Sources

* * * * * * * * * * * * * * * * * * * * * * {{DEFAULTSORT:Cordon del Azufre Complex volcanoes Volcanoes of Atacama Region Volcanoes of Catamarca Province Subduction volcanoes Mountains of Argentina Mountains of Chile Argentina–Chile border International mountains of South America Volcanoes of Antofagasta Region