Cordón de Puntas Negras is a volcanic chain located east of the

Salar de Atacama Salar de Atacama is the largest salt flat in Chile. It is located south of San Pedro de Atacama, is surrounded by mountains, and has no drainage outlets. In the east it is enclosed by the main chain of the Andes, while to the west lies a secondar ...

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 ...

Antofagasta Antofagasta () is a port city in northern Chile, about north of Santiago. It is the capital of Antofagasta Province and Antofagasta Region. According to the 2015 census, the city has a population of 402,669. After the Spanish American wars ...

Region. Cordón de Puntas Negras is constructed along the major Calama–Olacapato–El Toro fault and is long. The long volcanic chain intersects with the long Cordón Chalviri volcanic chain. Both chains cover a surface area of and contain cones, vents, lava domes, lava flows and maars, including a lava dome and silicic flow with a surface area of . Puntas Negras specifically covers an area of and is the highest summit in the chain and features a wide crater and a long

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...

. Puntas Negras runs from the

Chiliques Chiliques is a stratovolcano located in the Antofagasta Region of Chile. Chiliques is capped off by a wide summit crater, which contains two crater lakes. One of these lakes is found in the northern part and the other east-southeastern part ...

volcano on the north to volcán Puntas Negras () almost to the SE. The Puntas Negras Volcano forms the common endpoint of two chains of volcanoes in a V-shaped configuration. The southern leg of the V is called "Cordón Chalviri" whose other extreme is the Cerro Tuyajto, SW of Puntas Negras and at the same distance SE of the

Miñiques Miñiques is a massive volcanic complex containing a large number of craters, lava domes and flows, located in the Antofagasta Region of Chile. Located south of Volcán Chiliques and west of Cordón Puntas Negras, it is part of a frequentl ...

volcano. Several small volcanic centres and lava flows are found here, including Aguas Calientes, Cerros Cenizas, Chinchilla and Laguna Escondida which have well preserved craters. The volcanic chain is associated with a topographic anomaly in the region, a property that other volcanoes in the area also have. Rocks in the chain are

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 predomi ...

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 ...

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. ...

containing

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 alumino ...

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 rocks ...

and

pyroxene The pyroxenes (commonly abbreviated to ''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 calcium (Ca), sodium (Na), iron (Fe II) ...

. Magmas from this volcanic chain have 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 mag ...

composition formed by partial melting of a

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 ...

, with research indicating a decrease in SiO₂ concentration over time. In the Tuyajto group, past

fumarolic A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

activity has bleached the volcanic rocks in the summit region. The basement beneath the chain is composed from

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

marine sediments that were later deformed by the Acadian orogeny. The

La Pacana La Pacana is a Miocene age caldera in northern Chile's Antofagasta Region. Part of the Central Volcanic Zone of the Andes, it is part of the Altiplano-Puna volcanic complex, a major caldera and silicic ignimbrite volcanic field. This volcanic f ...

caldera is buried beneath Puntas Negras. Both the 3.2 ± 0.3 Patao ignimbrite and the 2.4 ± 0.4 mya Pampa Chamaca or Tuyajto

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 ...

from

may have been erupted from beneath Puntas Negras. the Tuyajto ignimbrite is 530,000 ± 170,000 years old.

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 alumino ...

s in

andesitic 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 ...

lavas have been dated 0.7 ± 0.3 to 0.3 ± 0.2 million years ago. Volcan Puntas Negras has generated postglacial lava flows and a large lava dome west of Puntas Negras may be of Holocene age. An

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...

basalt Basalt (; ) is an aphanite, 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 planetary surface, surface of a terrestrial ...

flow from the northern part of the chain extends over towards Salar el Laco and may be of late Holocene age. The youngest volcanic centre appears to be located southeast of Laguna Escondida. Historical eruptions may have occurred in the Chalviri chain. A zone of anomalous electrical conductivity down to depths of extends north to

Lascar A lascar was a sailor or militiaman from the Indian subcontinent, Southeast Asia, the Arab world, British Somaliland, or other land east of the Cape of Good Hope, who was employed on European ships from the 16th century until the middle of the 2 ...

volcano. Cerro Overo at the southeastern end of Puntas Negras has been undergoing active

deformation Deformation can refer to: * Deformation (engineering), changes in an object's shape or form due to the application of a force or forces. ** Deformation (physics), such changes considered and analyzed as displacements of continuum bodies. * Defor ...

, with a previously observed pattern of subsidence before 2003–2005 switching to a pattern of inflation. Filling and emptying of a magma reservoir linked to Puntas Negras may be the cause for these deformation patterns. Future eruptions may threaten mining operations at El Laco and . The volcanic chain forms a water divide in the Andes, separating the

Puna de Atacama The Puna de Atacama or Atacama Plateau''Atacama Plateau''
article at the ''

Laguna Miscanti Miscanti Lake (Spanish: ''Laguna Miscanti'') is a brackish water lake located in the altiplano of the Antofagasta Region in northern Chile. Cerro Miñiques volcano and Cerro Miscanti tower over this lake. This large heart-shaped lake has a deep ...

and Laguna Miniques. A catchment area of for the Laguna Miscanti lies in the Cordón de Puntas Negras. Puntas Negras has been affected by

glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

during the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

, with

moraine A moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice shee ...

s reaching up to altitude. Possibly, the entire chain was covered with glaciers, and certainly the southern part where several sets of moraines and glacial

trimline The Trimline telephone is a series of telephones that was produced by Western Electric, the manufacturing unit of the Bell System. These telephones were first introduced in 1965 and are formally referred to as the ''No. 220 Hand Telepho ...

s have been identified. Water from Cordón de Puntas Negras is a principal water source for Laguna Miscanti.

References

{{DEFAULTSORT:Cordon de Puntas Negras Volcanoes of Antofagasta Region Mountains of Chile Stratovolcanoes of Chile

See also

References