Wheelwright caldera
26°45′00″S 68°37′30″W / 26.75000°S 68.62500°W[1] Wheelwright caldera is a
The caldera formed together with a major ignimbrite known as the Wheelwright ignimbrite, but the exact relationship between the two is not clear as the ignimbrite is not encountered within the caldera. The ignimbrite was emplaced around 6.6 ± 1.2 - 5.5 ± 0.8 million years ago. Later, a number of volcanoes such as Ermitaño and Peñas Blancas were constructed on the ring fault around the caldera, and lava domes developed within its confines.
Geography and geomorphology
It lies in the Andes of the Atacama Region, east of the Salar de Maricunga.[2] The caldera lies just southwest of the Chile-Argentina border, which southeast of the caldera is crossed by the Paso San Francisco.[1] The international road between Chile and Argentina passes south of the caldera complex;[3] the region is remote and often described as inimical to life.[4]
Wheelwright is part of the
The caldera is 22 kilometres (14 mi),[10][11] c. 19 kilometres (12 mi)[12] or 11 kilometres (6.8 mi)[13] wide and 300 metres (980 ft) deep, and is one of the best preserved circular structures of the southern Central Andes,[2] as well as one of its largest.[10] It has also been interpreted as being actually three nested calderas.[14] The Lomas de Montes lie along the northwestern and the Somma de Lars along the southeastern caldera margin.[15] The caldera is filled with sediments as well as a 4.4-4.0 million year old ignimbrite that probably originated in the Laguna Amarga caldera.[2]
The depression of the caldera features a crater lake, called Laguna Wheelwright.[16] It is a saltwater lake with high contents of arsenic and fluorine,[17] thus it is not safe for drinking.[18] Birds and other animals are found at the lake.[19]
Later volcanic centres decorate its rim, including
Geology
Off the western coast of South America,
Neighbouring volcanic centres to Wheelwright include
The region coincides with a lineament of volcanoes which forms the southern margin of the volcanically active Central Andes; south of this margin the
The oldest outcrops are found in the Cordillera Claudio Gay mountain range[21] just west of Wheelwright;[22] these outcrops are Paleozoic sediments and volcanic rocks.[21] Volcanic arc volcanism has been ongoing in the region since 180 million years ago and migrated eastward during that time, but the modern arc developed 26 million years ago when the Farallon Plate broke up.[23]
Climate
The region is dry, windy and has high
Eruption history
The Wheelwright caldera is the source of the Wheelwright ignimbrite, an
The caldera formed at the same time as the eruption of the ignimbrite, but relation between the two events is unclear; there are no intracaldera exposures of the ignimbrite. Possibly, the caldera was formed by a lateral eruption from a magma chamber.[2] It appears that two separate caldera collapses occurred, one 5 million years ago and the other 4 million years ago.[26] The time of caldera formation was also a time of vigorous volcanic activity in the region, which gave rise to stratovolcanoes as well as the Galán caldera farther east.[11] Locally, the Wheelwright caldera is also related to the neighbouring Laguna Amarga and Laguna Escondida calderas.[27]
The Ermitaño volcano is dated 4.4 - 3.8 million years ago, Peñas Blancas complex formed between 5 and 4.8 million years ago,
References
- ^ a b Baker, Gonzalez-Ferran & Rex 1987, p. 88.
- ^ SERNAGEOMIN (in Spanish). Puerto Varas: 9th Chilean Geological Congress. Archived from the original(PDF) on June 10, 2020. Retrieved 6 January 2018.
- ^ a b c d e Nüsser & Dame 2015, p. 68.
- ^ Nüsser & Dame 2015, p. 66.
- ^ a b Hora, Singer & Wörner 2007, p. 345.
- ^ a b c Hora, Singer & Wörner 2007, p. 344.
- ^ Baker, Gonzalez-Ferran & Rex 1987, p. 86.
- ^ a b Baker, Gonzalez-Ferran & Rex 1987, p. 85.
- ^ Mpodozis et al. 1995, p. 275.
- ^ a b c Gonzalez-Ferran, Baker & Rex 1985, p. 432.
- ^ a b c d e Baker, Gonzalez-Ferran & Rex 1987, p. 89.
- ^ ISBN 978-0-8137-0013-7.
- ^ a b c Guzmán et al. 2014, p. 185.
- ISSN 0040-1951.
- ^ a b Gonzalez-Ferran, Baker & Rex 1985, p. 426,431.
- ^ Aguirre & Clavero 2000, p. 2.
- ^ Aguirre & Clavero 2000, p. 3.
- ^ Aguirre & Clavero 2000, p. 4.
- ^ Aguirre & Clavero 2000, p. 1.
- ^ a b Gonzalez-Ferran, Baker & Rex 1985, p. 433.
- ^ a b Baker, Gonzalez-Ferran & Rex 1987, p. 87.
- ^ Gonzalez-Ferran, Baker & Rex 1985, p. 431.
- ^ Mpodozis et al. 1995, p. 274.
- ^ Nüsser & Dame 2015, p. 67.
- ^ Guzmán et al. 2014, p. 175.
- ^ Naranjo et al. 2018, p. 635.
- ^ Naranjo et al. 2018, p. 637.
- ^ Gonzalez-Ferran, Baker & Rex 1985, p. 433,434.
- ISSN 0361-0128.
Sources
- Aguirre, L.; Clavero, J. (August 2000). "Antecedentes fisicoquimicos preliminares de cuerpos de agua superficial del Altiplano de la III Region de Atacama, Chile" (PDF). SERNAGEOMIN (in Spanish). Puerto Varas: 9th Chilean Geological Congress. pp. 1–5. Retrieved 6 January 2018.
- Baker, P. E.; Gonzalez-Ferran, O.; Rex, D. C. (1 February 1987). "Geology and geochemistry of the Ojos del Salado volcanic region, Chile". Journal of the Geological Society. 144 (1): 85–96. ISSN 0016-7649.
- 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. ISSN 0040-1951.
- Guzmán, Silvina; Grosse, Pablo; Montero-López, Carolina; Hongn, Fernando; Pilger, Rex; Petrinovic, Ivan; Seggiaro, Raúl; Aramayo, Alejandro (December 2014). "Spatial–temporal distribution of explosive volcanism in the 25–28°S segment of the Andean Central Volcanic Zone". Tectonophysics. 636: 170–189. ISSN 0040-1951.
- Hora, John M.; Singer, Brad S.; Wörner, Gerhard (1 March 2007). "Volcano evolution and eruptive flux on the thick crust of the Andean Central Volcanic Zone: 40Ar/39Ar constraints from Volcán Parinacota, Chile". GSA Bulletin. 119 (3–4): 343–362. ISSN 0016-7606.
- Mpodozis, Constantino; Cornejo, Paula; Kay, Suzanne M.; Tittler, Andrew (1 December 1995). "La Franja de Maricunga: sintesis de la evolucion del Frente Volcanico Oligoceno-Mioceno de la zona sur de los Andes Centrales". Andean Geology (in Spanish). 22 (2): 273–313. ISSN 0718-7106.
- Naranjo, José Antonio; Villa, Víctor; Ramírez, Cristián; Arce, Carlos Pérez de (1 April 2018). "Volcanism and tectonism in the southern Central Andes: Tempo, styles, and relationships". Geosphere. 14 (2): 626–641. .
- Nüsser, Marcus; Dame, Juliane (2015). "Der Ojos del Salado in der Atacama: Forschungsgeschichte und aktuelle Probleme im trockensten Hochgebirge der Erde". HGG Journal (in German). 29: 66–81. Retrieved 6 January 2018.