18°28′S 69°12′W / 18.467°S 69.200°W[1] El Rojo Norte is a cinder cone in the Andes,[2] constructed on top of volcano debris in the Lauca basin.[1]
The cone is 150 metres (490 ft) high[3] and 300 metres (980 ft) wide at its foot. Its profile has been reduced by erosion;[1] the cone sits on an andesitic mound.[4] A lava flow containing mafic andesite is associated with the cone.[3] Phreatomagmatic deposits are also found.[4]
The cone is formed by reddish scoria.[1] Its rocks are basaltic andesite. It was erupted 3.1 ± 0.2 million years ago on the basis of potassium-argon dating.[2] Other dates are 3.05 ± 0.22, 3.35 ± 0.16 and 2.34 ± 0.16 mya. Which age is correct is unclear, but the cone is partly buried by the 2.72 mya old Lauca-Pérez ignimbrite indicating that it's older than this ignimbrite.[3]
References
edit- ^ a b c d Wigger, edited by Klaus-Joachim Reutter, Ekkehard Scheuber, Peter J. (1994). "Large- and Fine-Scale Geochemical Variations Along the Andean Arc of Northern Chile (17.5°– 22°S)". Tectonics of the Southern Central Andes Structure and Evolution of an Active Continental Margin. Berlin, Heidelberg: Springer Berlin Heidelberg. p. 81. doi:10.1007/978-3-642-77353-2_5. ISBN 978-3-642-77353-2.
{{cite book}}:|first1=has generic name (help)CS1 maint: multiple names: authors list (link) - ^ a b Charrier, Reynaldo; Chávez, Alvaro N.; Elgueta, Sara; Hérail, Gérard; Flynn, John J.; Croft, Darin A.; Wyss, André R.; Riquelme, Rodrigo; García, Marcelo (May 2005). "Rapid tectonic and paleogeographic evolution associated with the development of the Chucal anticline and the Chucal-Lauca Basin in the Altiplano of Arica, northern Chile". Journal of South American Earth Sciences. 19 (1): 35–54. Bibcode:2005JSAES..19...35C. doi:10.1016/j.jsames.2004.06.008.
- ^ a b c 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. 27 (2): 205–240.
- ^ a b Kött, A.; Gaupp, R.; Wörner, G. (December 1995). "Miocene to recent history of the western Altiplano in northern Chile revealed by lacustrine sediments of the Lauca basin (18°15'-18°40' S/69°30'-69°05' W)". Geologische Rundschau. 84 (4): 770. Bibcode:1995GeoRu..84..770K. doi:10.1007/BF00240567. S2CID 129479890.
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