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 in t ...
at the border of
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
and
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 ...
.
Falso Azufre is elongated in east–west direction and contains craters and lava domes; most craters have diameters of with the exception of the main crater, which is wide.Grosse, et al. 2018, p. 12 The highest summit Cerro Falso Azufre lies at the western end in Chile, which has mostly generated pyroclastic material from craters. The probably youngest segment of the volcano is the eastern section in Argentina, where two lava domes and two cones are located; these form the Dos Conos volcano. Some lava flows linked to Dos Conos are up to long.Grosse, et al. 2018, p. 13 The oldest is known as the Kunstmann edifice on the northwestern side of Falso Azufre; Kunstmann volcano features a wide scar formed by a
sector collapse
A sector collapse is the collapse of a portion of a volcano due to a phreatic eruption, an earthquake, or the intervention of new magma. Occurring on many volcanoes, sector collapses are generally one of the most hazardous volcanic events, and will ...
. Falso Azufre with a base surface of is one of the biggest volcanoes in the area. The presence of two oppositely curved vent alignments gives the complex an arc-like shape which reaches heights of about above sea level.
Blocky lava flows, some of them quite large, form the bulk of the volcano. Neighbouring volcanoes are
Nevado San Francisco
Nevado San Francisco, or Cerro San Francisco (), is a stratovolcano on the border between Argentina and Chile, located just southeast of San Francisco Pass. It is considered extinct and is one of the several peaks in the area, of which the ch ...
, the
Laguna Amarga
Laguna Amarga is a caldera and associated ignimbrite in the Andes of northwestern Argentina.
Laguna Amarga is part of the southern Central Volcanic Zone and one among several Miocene-Pliocene-Pleistocene volcanic centres of this volcanic region. ...
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 Laguna Verde volcanoes; additional volcanics are of
Miocene
The Miocene ( ) is the first epoch (geology), 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 mea ...
to
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 The Kunstmann edifice probably counts as a separate volcano as well.
The volcano has erupted
trachyandesite
Trachyandesite is an extrusive igneous rock with a composition between trachyte and andesite. It has little or no free quartz, but is dominated by sodic plagioclase and alkali feldspar. It is formed from the cooling of lava enriched in alka ...
,
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 predo ...
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 ...
. The rocks contain
hornblende
Hornblende is a complex 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 in igneous and metamorphic rock ...
and pyroxene with a total content of 58-61% of SiO2 and form a
potassium
Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosph ...
-rich
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 m ...
suite. In some parts of the volcano, its rocks have suffered
hydrothermal
Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...
alteration.
A number of dates have been obtained on Falso Azufre; with the exception of the oldest ones on the Kunstmann edifice (3.5 to 2.9 million years ago) Falso Azufre has only yielded ages of less than one million years, with older dates found in the western part of the volcano and the younger dates of less than 400,000 years ago in the eastern part; the absolutely youngest date was obtained on a lava flow linked to Dos Conos; 160,000 ± 80,000 years ago. Falso Azufre could thus be considered an extinct volcano, although recent activity cannot be ruled out. While the remoteness of the volcano reduces any hazard potential future pyroclastic eruptions could impact
air traffic
Air Traffic are an English alternative rock band from Bournemouth signed to EMI Records. Formed in 2003, the band consists of Chris Wall (piano, lead vocals), David Ryan Jordan (Drums), Tom Pritchard (guitar) and Jim Maddock (bass guitar).
Th ...
over the region and east of it; further a major road is close to the volcano.
Falso Azufre is part of the Central Volcanic Zone of the
Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
together with about 110 other Quaternary volcanoes, and lies in the southern sector of the volcanic zone;Grosse, et al. 2018, p. 2 other volcanic zones in the Andes are the Northern Volcanic Zone, the Southern Volcanic Zone and the Austral Volcanic Zone.Grosse, et al. 2018, p. 3 The history of volcanic activity is poorly known for most of these volcanoes owing to the lack of dating; only a few historical eruptions have been recorded, such as an eruption at
Ojos del Salado
Nevado Ojos del Salado is a dormant complex volcano in the Andes on the Argentina–Chile border. It is the highest volcano on Earth and the highest peak in Chile. The upper reaches of Ojos del Salado consist of several overlapping lava domes, ...
List of volcanoes in Chile
The Smithsonian Institution's Global Volcanism Program lists 105 volcanoes in Chile that have been active during the Holocene.List of volcanoes in Argentina
This is a list of active and extinct volcanoes in Argentina.
Volcanoes
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