Earth:Ojos de Maricunga

Template:Coord/display/intitle Ojos de Maricunga is a volcano in the Maricunga Belt of Chile (Mpodozis Cornejo), in the Cordillera Domeyko.(Muñoz 1894)

Ojos de Maricunga is part of the Maricunga Belt, a volcanic area of Oligocene to Pliocene age consisting of lava domes and stratovolcanoes(Lohmeier Schneider) that developed just south of the present-day Central Volcanic Zone of the Andes and is associated with metal ore deposits(Lohmeier Schneider). The volcano was active during a time in the Miocene where volcanism in the Maricunga belt had increased. Other volcanoes active at that time were Cadillal, Dona Ines, north Jotabeche, La Laguna, Pastillitos, Santa Rosa and Villalobos.(Mpodozis Cornejo)

Ojos de Maricunga is 4,985 metres (16,355 ft) high and has a circumference of 15 kilometres (9.3 mi). It is the largest stratovolcano of the middle Miocene in the Maricunga Belt (Kay Mpodozis). Its exposed surface consists mostly of andesitic lava flows(Mpodozis Cornejo) although the volcano itself is formed mostly by pyroclastic flows(Lohmeier Schneider). A northwest-southeast elongated, roughly 4 kilometres (2.5 mi) long crater or caldera caps off the edifice (Mpodozis Cornejo). It contains a lava dome formed by biotite and hornblende containing dacite (Kay Mpodozis). Ignimbrites occur on the foot of the volcano, mostly on the eastern and southwestern side (Mpodozis Cornejo). There appear to be at least two ignimbrites whose composition and age resembles that of Ojos de Maricunga and neighbouring volcanoes (Kay Mpodozis). In fact, Ojos de Maricunga may be the source of ash flows (Gonzalez-Ferran Baker).

Volcanic rocks include andesite and dacite, with potassium contents in the middle to high range and elemental compositions reflecting volcanic arc petrologies (Kay Mpodozis). Exposures in the caldera have a porphyritic texture (Gonzalez-Ferran Baker). Overall SiO₂ content of Ojos de Maricunga rocks is 61-64% (Kay Mpodozis) and dominant phenocryst phases are plagioclase and additional clinopyroxene, magnetite, orthopyroxene and quartz(Lohmeier Schneider).

The volcano was active 16-15 million years ago (Kay Mpodozis). Potassium-argon dating has been performed both on the central lava dome and the andesite lava flows. The former show ages of 15.8 ± 0.9 million years ago and the latter 15.1 ± 0.7 million years ago (Mpodozis Cornejo). Other ages are 16.2 ± 0.6 and 16.1 ± 0.8 million years ago for the slope deposits (Kay Mpodozis). One ignimbrite was erupted 15.8 million years ago.(Coira Galli) The Ojos de Maricunga ignimbrites were once considered to be Quaternary and that the "San Andes" flows dated at 9.15 ± 0.15 million years ago originated from Ojos de Maricunga (Gonzalez-Ferran Baker). Presently, the volcano is partially eroded (Lohmeier Schneider).

Santa Rosa volcano has a similar architecture and lies southwest of Ojos de Maricunga. The Salar de Maricunga lies northeast of Ojos de Maricunga. The Laguna Santa Rosa lies southeast of Ojos de Maricunga and the west flowing Quebrada Paipate originates on the volcano's southern slope (Mpodozis Cornejo). The watershed of the Copiapo River borders Ojos de Maricunga to the west (Muñoz 1894). The Cerro Maricunga gold mining project is located on Ojos de Maricunga (Lohmeier Schneider).

References

• Coira, Beatriz; Galli, Claudia Inés; Mahlburg Kay, Suzanne; Kay, Robert W.; Flores, Patrocinio (2014-06-01). "Niveles piroclásticos como herramientas de correlación en los depósitos cenozoicos del grupo Payogastilla, Valles Calchaquí, Tonco y Amblayo, en el noroeste de Argentina". Revista de la Asociación Geológica Argentina 71 (2): 147–160. ISSN 0004-4822. http://www.scielo.org.ar/scielo.php?script=sci_abstract&pid=S0004-48222014000200001&lng=es&nrm=iso&tlng=en. 
• Gonzalez-Ferran, O.; Baker, P.E.; Rex, D.C. (March 1985). "Tectonic-volcanic discontinuity at latitude 27° south Andean Range, associated with Nazca Plate Subduction". Tectonophysics 112 (1–4): 423–441. doi:10.1016/0040-1951(85)90189-1. 
• Kay, Suzanne Mahlburg; Mpodozis, Constantino; Tittler, Andrew; Cornejo, Paula (1994-12-01). "Tertiary Magmatic Evolution of the Maricunga Mineral Belt in Chile". International Geology Review 36 (12): 1079–1112. doi:10.1080/00206819409465506. ISSN 0020-6814. 
• Lohmeier, Stephanie; Schneider, Albrecht; Belyatsky, Boris; Lehmann, Bernd (June 2019). "Magmatic evolution of the Cerro Maricunga gold porphyry-epithermal system, Maricunga belt, N-Chile". Journal of South American Earth Sciences 92: 374–399. doi:10.1016/j.jsames.2019.03.003. 
• Mpodozis, Constantino; Cornejo, Paula; Kay, Suzanne M.; Tittler, Andrew (1995-12-01). "La Franja de Maricunga: sintesis de la evolucion del Frente Volcanico Oligoceno-Mioceno de la zona sur de los Andes Centrales" (in es). Andean Geology 22 (2): 273–313. ISSN 0718-7106. http://www.andeangeology.cl/index.php/revista1/article/view/V22n2-a10. 
• Muñoz, Santiago (1894-01-01). Jeografía descriptiva de las provincias de Atacama i Antofagasta. Santiago de Chile : Impr. Gutenberg. https://archive.org/details/jeografiadescri00munogoog.