Negro de Chorrillos

Coordinates: 24°16′S 66°24′W / 24.267°S 66.400°W / -24.267; -66.400[1] Negro de Chorrillos is a volcano in the Andes.

Negro de Chorrillos lies on the Puna. Cerro Tuzgle and the major Calama-Olacapato-El Toro fault lie nearby, as do active and inactive hot springs.[2] This major fault zone is accompanied by a chain of volcanic systems.[3] The basement in the region is formed by Precambrian-Cambrian units with Cretaceous-Oligocene sediments[4] and ignimbrites from the Aguas Calientes caldera.[5]

Negro de Chorrillos covers a surface of about 5.88 square kilometres (2.27 sq mi).[6] It has erupted lava flows of the aa lava and block lava type, which flowed 4 kilometres (2.5 mi) down a valley. Ash fall, lava bombs and scoria are also found.[7] Both Negro de Chorrillos and neighbouring San Jerónimo centres have heights of 300–450 metres (980–1,480 ft) and widths of 750–950 metres (2,460–3,120 ft).[5] The volume of both centres is less than 0.1 cubic kilometres (0.024 cu mi).[8] Negro de Chorrillos may be the source of local pyroclastic flows, and material eroded from such flows.[9]

The Negro de Chorrillos monogenetic volcano formed during the Pleistocene. Together with neighbouring San Geronimo volcano it lies on a left-trending strike-slip fault,[10] the El Toro fault.[11] Nearby faults include the Incachule fault to the south and the Chorrillos fault to the north, which actually crosses the Negro de Chorrillos centre.[12] Both faults are part of the Calama-Olacapato-El Toro fault.[7] An onset of crustal tension probably facilitated the ascent of magma.[5]

Negro de Chorrillos like San Geronimo has erupted basaltic trachyandesite to trachyandesite,[13] both shoshonite magmas.[11] They formed over the volcanic back-arc of the Peru-Chile Trench; low percentage melts that were contaminated with lithospheric material formed these two centres.[14]

Eruption dates from the volcano are contradictory; radiometric dates range from 200,000 ± 150,000 years ago,[9] 450,000 years ago,[10] or 200,000 ± 80,000 years ago according to potassium-argon dating.[7] Lava flows from Negro de Chorrillos were later cut by fault offset.[15]

References

  1. ↑ Coira, B.; Kay, S. Mahlburg; Viramonte, J. (1993-08-01). "Upper Cenozoic Magmatic Evolution of the Argentine Puna—a Model for Changing Subduction Geometry". International Geology Review. 35 (8): 707. doi:10.1080/00206819309465552. ISSN 0020-6814.
  2. ↑ Giordano et al. 2013, p. 77.
  3. ↑ Petrinovic et al. 2006, p. 241.
  4. ↑ Giordano et al. 2013, p. 79.
  5. 1 2 3 Petrinovic et al. 2006, p. 244.
  6. ↑ Giordano et al. 2013, p. 83.
  7. 1 2 3 Kay, Coira & Mpodozis 2008, p. 138.
  8. ↑ Schreiber, U.; Schwab, K. (1991). "Geochemistry of quaternary shoshonitic lavas related to the Calama-Olacapato-El Toro Lineament, NW Argentina". Journal of South American Earth Sciences. 4 (1–2): 74. doi:10.1016/0895-9811(91)90019-h.
  9. 1 2 Seggiaro, Raúl Eudocio; Guzman, Silvina; Pereyra, Ricardo; Coppolecchia, Mariana; Cegarra, Marcelo (2016-12-30). "NEOTECTÓNICA Y VOLCANISMO MONOGENÉTICO CUATERNARIO SOBRE EL SEGMENTO CENTRAL DEL LINEAMIENTO CALAMA OLACAPATO TORO (COT),". Revista de la Asociación Geológica Argentina (in Spanish). 73 (4): 475. ISSN 1851-8249.
  10. 1 2 Giordano et al. 2013, p. 78.
  11. 1 2 Kay, Coira & Mpodozis 2008, p. 433.
  12. ↑ Kay, Coira & Mpodozis 2008, p. 137.
  13. ↑ Petrinovic et al. 2006, p. 245.
  14. ↑ Kay, Coira & Mpodozis 2008, p. 135.
  15. ↑ Lanza, F.; Tibaldi, A.; Bonali, F. L.; Corazzato, C. (2013-05-08). "Space–time variations of stresses in the Miocene–Quaternary along the Calama–Olacapato–El Toro Fault Zone, Central Andes". Tectonophysics. 593: 33–56. doi:10.1016/j.tecto.2013.02.029.

Sources

  • Giordano, Guido; Pinton, Annamaria; Cianfarra, Paola; Baez, Walter; Chiodi, Agostina; Viramonte, José; Norini, Gianluca; Groppelli, Gianluca (2013-01-01). "Structural control on geothermal circulation in the Cerro Tuzgle–Tocomar geothermal volcanic area (Puna plateau, Argentina)". Journal of Volcanology and Geothermal Research. 249: 77–94. doi:10.1016/j.jvolgeores.2012.09.009.
  • Kay, Suzanne Mahlburg; Coira, Beatriz; Mpodozis, Constantino (2008-01-01). "Field trip guide: Neogene evolution of the central Andean Puna plateau and southern Central Volcanic Zone". Field Guides. 13: 117–181. doi:10.1130/2008.0013(05). ISSN 2333-0937.
  • Petrinovic, I. A.; Riller, U.; Brod, J. A.; Alvarado, G.; Arnosio, M. (2006-04-15). "Bimodal volcanism in a tectonic transfer zone: Evidence for tectonically controlled magmatism in the southern Central Andes, NW Argentina". Journal of Volcanology and Geothermal Research. 152 (3–4): 240–252. doi:10.1016/j.jvolgeores.2005.10.008.
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