Cordón de Puntas Negras

Cordón de Puntas Negras

Cordón de Puntas Negras seen from Laguna Miscanti with Cerro Miscanti in the foreground (left).
Highest point
Elevation 5,852 m (19,199 ft) [1]
Coordinates 23°44′34″S 67°32′03″W / 23.74278°S 67.53417°W / -23.74278; -67.53417Coordinates: 23°44′34″S 67°32′03″W / 23.74278°S 67.53417°W / -23.74278; -67.53417
Geography
Location Chile
Parent range Andes
Geology
Mountain type Stratovolcanoes
Last eruption Unknown

Cordón de Puntas Negras is a 500 km2 (193 sq mi) volcanic chain located east of the Salar de Atacama in Chile's II Region.

Cordón de Puntas Negras is constructed along the major Calama–Olacapato–El Toro fault[2]:213 and is 70 kilometres (43 mi) long.[3] The volcanic chain intersects with the Cordón Chalviri volcanic chain. Both chains cover a surface area of 500 square kilometres (190 sq mi) and contain cones, vents, lava domes, lava flows and maars,[4] including a lava dome and silicic flow with a surface area of 13 square kilometres (5.0 sq mi).[1] Puntas Negras specifically covers an area of 400 square kilometres (150 sq mi),[5] which runs from the Chiliques volcano on the north to volcán Puntas Negras (5,852 m (19,199 ft)) 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 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.[1]

Rocks in the chain are andesite, basaltic andesite and dacite.[1] Magmas from this volcanic chain have a calc-alkaline composition formed by partial melting of a mantle wedge,[2]:218,225 with research indicating a decrease in SiO2 concentration over time.[6]

The basement beneath the chain is composed from Ordovician marine sediments that were later deformed by the Acadian orogeny.[7] The 35 by 70 kilometres (22 mi × 43 mi) La Pacana caldera is buried beneath Puntas Negras.[1] The 2.4 ± 0.4 mya Pampa Chamaca or Tuyajto ignimbrite from La Pacana may have been erupted from beneath Puntas Negras.[8][9]

Biotites in andesitic lavas have been dated 0.7 ± 0.3 to 0.3 ± 0.2 million years ago.[10] Volcan Puntas Negras has generated postglacial lava flows.[3] An olivine basalt flow from the northern part of the chain extends over 10 kilometres (6.2 mi) towards Salar el Laco and may be of late Holocene age.[6] The youngest volcanic centre appears to be located southeast of Laguna Escondida.[1] A zone of anomalous electrical conductivity down to depths of 6 kilometres (3.7 mi) extends north to Lascar volcano.[11] Cerro Overo at the southeastern end of Puntas Negras has been undergoing active deformation,[3]:1369 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.[3]

The volcanic chain forms a water divide in the Andes, separating the Puna de Atacama from the basins Laguna Miscanti and Laguna Miniques.[12]:176 A catchment area of 320 square kilometres (120 sq mi) for the Laguna Miscanti lies in the Cordón de Puntas Negras.[13] Puntas Negras has been affected by glaciation during the Pleistocene,[14] with moraines reaching up to 4,400 metres (14,400 ft) altitude. Possibly, the entire chain was covered with glaciers.[5]

See also

References

  1. 1 2 3 4 5 6 "Cordon de Puntas Negras". Global Volcanism Program. Smithsonian Institution.
  2. 1 2 Matteini, M.; Mazzuoli, R.; Omarini, R.; Cas, R.; Maas, R. (February 2002). "The geochemical variations of the upper cenozoic volcanism along the Calama–Olacapato–El Toro transversal fault system in central Andes (~24°S): petrogenetic and geodynamic implications". Tectonophysics. 345 (1–4): 211–227. doi:10.1016/S0040-1951(01)00214-1.
  3. 1 2 3 4 Henderson, S. T.; Pritchard, M. E. (May 2013). "Decadal volcanic deformation in the Central Andes Volcanic Zone revealed by InSAR time series". Geochemistry, Geophysics, Geosystems. 14 (5): 1358–1374. doi:10.1002/ggge.20074.
  4. ↑ Cabrol, Nathalie A.; Grin, Edmond A.; Chong, Guillermo; Minkley, Edwin; Hock, Andrew N.; Yu, Youngseob; Bebout, Leslie; Fleming, Erich; Häder, Donat P.; Demergasso, Cecilia; Gibson, John; Escudero, Lorena; Dorador, Cristina; Lim, Darlene; Woosley, Clayton; Morris, Robert L.; Tambley, Cristian; Gaete, Victor; Galvez, Matthieu E.; Smith, Eric; Uskin-Peate, Ingrid; Salazar, Carlos; Dawidowicz, G.; Majerowicz, J. (June 2009). "The High-Lakes Project". Journal of Geophysical Research: Biogeosciences. 114 (G2): n/a–n/a. doi:10.1029/2008JG000818.
  5. 1 2 Schröder, Hilmar (September 2001). "Kommentar zu den Anmerkungen von Bettina Jenny, Klaus Kammer und Bruno Messerli (Erdkunde 55, 2001, 288–289)". Erdkunde (in German). JSTOR. 55 (3): 289.
  6. 1 2 Zeil, Werner (December 1964). "Die Verbreitung des jungen Vulkanismus in der Hochkordillere Nordchiles". Geologische Rundschau (in German). 53 (2): 753. doi:10.1007/BF02054561.
  7. ↑ Stratabound Ore Deposits in the Andes. Berlin, Heidelberg: Springer Berlin Heidelberg. 1990. p. 681. ISBN 978-3-642-88282-1. Retrieved 24 February 2016.
  8. ↑ de Silva, Shanaka L.; Gosnold, William D. (November 2007). "Episodic construction of batholiths: Insights from the spatiotemporal development of an ignimbrite flare-up". Journal of Volcanology and Geothermal Research. 167 (1–4): 325. doi:10.1016/j.jvolgeores.2007.07.015.
  9. ↑ Gardeweg, Moyra; Ramirez, Carlos F. (June 1987). "La Pacana caldera and the Atana Ignimbrite ? a major ash-flow and resurgent caldera complex in the Andes of northern Chile". Bulletin of Volcanology. 49 (3): 563. doi:10.1007/BF01080449.
  10. ↑ Naranjo, J.A.; Henríquez, F. "Geocronología K-Ar y antecedentes paleoambientales del volcanismo de óxido de fierro de El Laco" (PDF). researchgate.net (in Spanish). XII Congreso Geológico Chileno. Retrieved 24 February 2016.
  11. ↑ Díaz, Daniel; Brasse, Heinrich; Ticona, Faustino (March 2012). "Conductivity distribution beneath Lascar volcano (Northern Chile) and the Puna, inferred from magnetotelluric data". Journal of Volcanology and Geothermal Research. 217–218: 27. doi:10.1016/j.jvolgeores.2011.12.007.
  12. ↑ Niemeyer, Hans F. Hoyas Hydrograficas de Chile: Segunda region (PDF) (in Spanish). Retrieved 24 February 2016.
  13. ↑ Valero-Garcés, Blas L.; Grosjean, Martin; Kelts, Kerry; Schreier, Hans; Messerli, Bruno (July 1999). "Holocene lacustrine deposition in the Atacama Altiplano: facies models, climate and tectonic forcing". Palaeogeography, Palaeoclimatology, Palaeoecology. 151 (1–3): 105. doi:10.1016/S0031-0182(99)00018-8.
  14. ↑ Naranjo, Jose A.; Henrquez, Fernando; Nystrom, Jan O. (19 January 2010). "Metasomatismo de contacto subvolcanico en el Complejo Volcanico El Laco.". Andean Geology. 37 (1): 111. doi:10.5027/andgeoV37n1-a05.
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