25°15′S 67°50′W / 25.250°S 67.833°W / -25.250; -67.833[1] Cerro Archibarca is a volcano in the Andes. It covers a surface area of 20 square kilometres (7.7 sq mi). Lava flows descend from a conical edifice.: 19 [2] It was active 11 million years ago.[3] The youngest deposits are eroded andesites on the northern side.[4]

A major volcaniclastic unit is associated with Archibarca, named the La Torre formation after the valley where its lower bright red unit reaches a thickness of 20 metres (66 ft). The red unit is formed from unconsolidated pyroclastics with spherical clasts (3 centimetres (1.2 in) up to 10 centimetres (3.9 in)). Granite and pumice are materials also present in this unit. The upper white unit is a thick pyroclastic flow from Archibarca. A 30 metres (98 ft) thick rhyolitic flow with banding structures is also present as well as an associated lava dome that intruded the La Torre formation on the volcano's southern side.[4]

Andesites from this volcano are partly derived from crustal assimilation, with the crustal component constituting 40% of total rock.: 103 [2] The Caballo Muerto and Archibarca ignimbrites may be derived from this volcano.[5]

References

  1. ↑ Kraemer, B.; Adelmann, D.; Alten, M.; Schnurr, W.; Erpenstein, K.; Kiefer, E.; van den Bogaard, P.; Görler, K. (March 1999). "Incorporation of the Paleogene foreland into the Neogene Puna plateau: The Salar de Antofalla area, NW Argentina". Journal of South American Earth Sciences. 12 (2): 157–182. doi:10.1016/S0895-9811(99)00012-7.
  2. 1 2 Kraemer, Bernhard (1999). Eine geochemische Traverse quer zum mittelmiozänen magmatischen Bogen im südlichen Bereich der zentralen vulkanischen Zone der Anden (ZVZ, 25 - 2630'S, 6730'- 69W) (in German). Berlin: Selbstverlag Fachbereich Geowissenschaften, FU Berlin. ISBN 9783895820687. Retrieved 22 November 2015.
  3. ↑ Richards, Jeremy P.; Ullrich, Thomas; Kerrich, Robert (April 2006). "The Late Miocene–Quaternary Antofalla volcanic complex, southern Puna, NW Argentina: Protracted history, diverse petrology, and economic potential". Journal of Volcanology and Geothermal Research. 152 (3–4): 197–239. doi:10.1016/j.jvolgeores.2005.10.006.
  4. 1 2 Alonso, Ricardo. "LEXICO ESTRATIGRÁFICO DE LA ARGENTINA: NEÓGENO" (PDF). Servicio Geológico Minero Argentino (SEGEMAR) (in Spanish). Buenos Aires: Government of Argentina. pp. 17–18. Archived from the original (PDF) on 22 November 2015. Retrieved 22 November 2015.
  5. ↑ Schnurr, W.B.W.; Trumbull, R.B.; Clavero, J.; Hahne, K.; Siebel, W.; Gardeweg, M. (September 2007). "Twenty-five million years of silicic volcanism in the southern central volcanic zone of the Andes: Geochemistry and magma genesis of ignimbrites from 25 to 27 °S, 67 to 72 °W". Journal of Volcanology and Geothermal Research. 166 (1): 17–46. doi:10.1016/j.jvolgeores.2007.06.005.
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