Cerro Macá 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 peri ...

located to the north of the

Aisén Fjord Aysén Fjord is an ~70 km long fjord stretching east from a skerry-guarded ( skjærgård) region called Moraleda Channel ( es, Canal Moraleda), which is a body of water separating the Chonos Archipelago from the mainland of Chile. It is locat ...

and to the east of the Moraleda Channel, in the Aysén del General Carlos Ibáñez del Campo 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 eas ...

. This glacier-covered volcano lies along the regional

Liquiñe-Ofqui Fault The Liquiñe-Ofqui Fault is major geological fault that runs a length of roughly in a NNE-SSW orientation and exhibits current seismicity. It is located in the Chilean Northern Patagonian Andes. It is a dextral intra-arc strike-slip fault. Most ...

Zone. Cerro Macá is a relatively small volcano with a volume of only . It has a summit elevation of approximately 2,300 m above sea level and features

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 over many years, often centuries. It acquires distinguishing features, such a ...

s that in 2011 covered an area of . The edifice is partially eroded and 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 ...

is probably the origin of a large steep sided depression in the summit area.

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 with associated

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 un ...

s are found on its southwestern flank but also on the other slopes of the volcano, as far down as sea level and in the Bahia Aysen. The volcano is part of the southernmost

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 Chile, where volcanism is caused by the

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...

of 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 N ...

. Other volcanoes in the area are

Melimoyu Melimoyu is a stratovolcano (Mapudungun ''meli''="four"; the name means "four breasts".) in Chile. It is an elongated volcanic complex that contains two nested calderas of and width. An ice cap has developed on the volcano with a couple of out ...

, Mentolat, Cay and Cerro Hudson. Macá specifically is formed by

basalt 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 Am ...

. 1,440 ± 40 calibrated radiocarbon years ago a moderate

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 viscous magma su ...

deposited the MAC1

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 r ...

, which reaches thicknesses of east of Macá. Ash from past eruptions has been tentatively identified close to

Cochrane Lake Cochrane may refer to: Places Australia * Cochrane railway station, Sydney, a railway station on the closed Ropes Creek railway line Canada * Cochrane, Alberta * Cochrane Lake, Alberta * Cochrane District, Ontario ** Cochrane, Ontario, a town wi ...

. A more recent eruption occurred from the Bahía Pérez

cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruption ...

on the southwestern flank in 1560 ± 110 years. In the early 20th century volcanic activity was observed at Ensenada Pérez, close to the southwestern flank of Macá.

Footnotes

References

"Monte Maca, Chile" on Peakbagger
Volcanoes of Aysén Region Mountains of Chile Stratovolcanoes of Chile Holocene stratovolcanoes {{Aisén-geo-stub

See also

Footnotes

References