El Rojo Sur

Coordinates: 20°50′S 68°37′W / 20.833°S 68.617°W / -20.833; -68.617[1] El Rojo Sur is a monogenetic volcano in the Andes,[1] in the form of a cone.[2]

It is similar to El Rojo Norte 260 kilometres (160 mi) farther north.[1] A mafic andesite lava flow was erupted from the 100 metres (330 ft) high cone that also features red scoria. Ages obtained by potassium-argon dating are 2.93±0.13, 3.4±0.4 and 3.23±0.12 mya.[3]

Rojo Sur erupted undifferentiated mafic magmas. Its lead isotope composition is different from the composition of that segment of the Andes, being non-radiogenic. This isotope signature may be the effect of assimilation of deeper basement rocks during magma formation.[2] In addition, the magmas are rich in incompatible elements.[4]

References

  1. 1 2 3 Wigger, edited by Klaus-Joachim Reutter, Ekkehard Scheuber, Peter J. (1994). Tectonics of the Southern Central Andes Structure and Evolution of an Active Continental Margin. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 81–83. ISBN 978-3-642-77353-2. Retrieved 3 April 2016.
  2. 1 2 Wörner, Gerhard; Moorbath, Stephen; Harmon, Russell S. (1992). "Andean Cenozoic volcanic centers reflect basement isotopic domains". Geology. 20 (12): 1103. doi:10.1130/0091-7613(1992)020<1103:ACVCRB>2.3.CO;2.
  3. ↑ Wörner, Gerhard; Hammerschmidt, Konrad; Henjes-Kunst, Friedhelm; Lezaun, Judith; Wilke, Hans (December 2000). "Geochronology (40Ar/39Ar, K-Ar and He-exposure ages) of Cenozoic magmatic rocks from Northern Chile (18-22°S): implications for magmatism and tectonic evolution of the central Andes". Revista Geológica de Chile. Santiago: SciELO. 27 (2). doi:10.4067/S0716-02082000000200004. ISSN 0716-0208. Retrieved 1 October 2015.
  4. ↑ Worner, Gerhardt; Lopez-Escobar, Leopoldo; Moorbath, Stephen; Horn, Susan; Entenmann, Jürgen; Harmon, Russel S.; Davidson, Jon D. (1992). "Variaciones geoquimicas, locales y regionales, en el frente volcanico cuaternario de los Andes centrales (17°30'-22°00'S), norte de Chile". Andean Geology. 19 (a). doi:10.5027/andgeoV19n1-a03. Retrieved 8 December 2015.
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