Chimpa

Chimpa is a volcano in Argentina, close to the border between the Jujuy Province and the Salta Province.[1] The volcano is of Miocene age,[2] one date given being 12 million years ago.[3]

Chimpa has two summits, the 4,856 metres (15,932 ft) high Cerro Chimpa and the 4,796 metres (15,735 ft) high Cerro Cajón. The volcanic edifice was constructed in two stages, the first consisting of explosive and the second of effusive activity. The explosive activity generated ignimbrites and pyroclastic flows. On top of these, many poorly preserved lava flows were emplaced in a radial pattern and constitute three separate formations.[1]

The volcanic rocks are of basaltic andesite to andesite composition, defining a potassium-rich calc-alkaline suite. They contain phenocrysts of biotite, hornblende, ilmenite, magnetite, orthopyroxene, plagioclase and quartz. Mafic inclusions occur in some eruption products.[1]

The basement of the region is formed by various formations of Precambrian to Tertiary age, some of which crop out around the volcano. This basement is cut by various faults, which mark an uplift that forms the Creston Alto de La Aguada east of Chimpa volcano, as well as the Calama-Olacapato-El Toro lineament and associated faults which runs south of the Chimpa volcano and has localized the formation of volcanoes along its path[1] and also influenced the activity of Chimpa.[3] Cerro Rumio is another volcano which crops out south of Chimpa and is in part buried by Chimpa's deposits.[1]

References
  1. Arnosio, Marcelo (2010). "Evidencia textural y geoquímica de mezcla de magmas en el volcán Chimpa, Puna Salteña". Revista de la Asociación Geológica Argentina (in Spanish). 66 (1–2): 253–270. ISSN 0004-4822.
  2. Norini, G.; Cogliati, S.; Baez, W.; Arnosio, M.; Bustos, E.; Viramonte, J.; Groppelli, G. (September 2014). "The geological and structural evolution of the Cerro Tuzgle Quaternary stratovolcano in the back‐arc region of the Central Andes, Argentina". Journal of Volcanology and Geothermal Research. 285: 214–228. doi:10.1016/j.jvolgeores.2014.08.023. ISSN 0377-0273.
  3. Acocella, V.; Gioncada, A.; Omarini, R.; Riller, U.; Mazzuoli, R.; Vezzoli, L. (June 2011). "Tectonomagmatic characteristics of the back-arc portion of the Calama-Olacapato-El Toro Fault Zone, Central Andes". Tectonics. 30 (3): n/a. doi:10.1029/2010TC002854. hdl:11336/13093.


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