Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar ages

Twenty-nine K-Ar ages for lavas and juvenile ejecta obtained from Hudson volcano in the southern end of the Southern Volcanic Zone and Lautaro volcano in the northern end of the Austral Volcanic Zone, which are separated by a 350 km-long volcanic gap near the Chile ridge subduction zone, were determ...

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Autores principales:	Orihashi,Yuji, Naranjo,José A., Motoki,Akihisa, Sumino,Hirochika, Hirata,Daiji, Anma,Ryo, Nagao,Keisuke
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2004
Materias:	Quaternary volcanic activity K-Ar dating Chilean Patagonia Ridge subduction Southern Volcanic Zone Austral Volcanic Zone Hudson volcano Lautaro volcano Caldera Unspiked method
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082004000200002
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spelling	oai:scielo:S0716-020820040002000022005-03-23Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar agesOrihashi,YujiNaranjo,José A.Motoki,AkihisaSumino,HirochikaHirata,DaijiAnma,RyoNagao,Keisuke Quaternary volcanic activity K-Ar dating Chilean Patagonia Ridge subduction Southern Volcanic Zone Austral Volcanic Zone Hudson volcano Lautaro volcano Caldera Unspiked method Twenty-nine K-Ar ages for lavas and juvenile ejecta obtained from Hudson volcano in the southern end of the Southern Volcanic Zone and Lautaro volcano in the northern end of the Austral Volcanic Zone, which are separated by a 350 km-long volcanic gap near the Chile ridge subduction zone, were determined using unspiked method that has significant sensitivity for dating young rocks (<0.1 Ma). It is newly revealed that Hudson is a significantly long-lived volcano; its activity started at ca. 1.0 Ma and continues to the Recent. The Hudson volcano has a well-preserved summit caldera complex of approximately 10 km in diameter, previously thought to be formed by a single event during the Holocene, perhaps at 6700 years BP. Our results for the K-Ar dating, however, indicate that the northeastern and southeastern flanks of the volcano formed at different times; formation of NE flank preceded that of SE flank. Aero-photographic observations indicate the presence of two or even three caldera rims. These data suggest that the Hudson volcano had a complex evolution, superimposing or partially nesting calderas rather than a simple caldera. The activity of the Lautaro volcano, began at ca. 0.17 Ma and has continued to the Recent, as it is indicated by our K-Ar first results. Though Lautaro volcano is a relatively large stratovolcano for Chilean Patagonia, the chemical and radiometric results indicate a narrow range in its variability when compared with those of the Hudson volcano. These narrow compositional and geochronological ranges suggest that the Lautaro volcano developed from a homogeneous magma chamber produced by slab melting during the late Quaternary, assuming that the sampled part of this heavily ice-mantled volcano, spans its full lifetimeinfo:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Revista geológica de Chile v.31 n.2 20042004-12-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082004000200002en10.4067/S0716-02082004000200002
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Quaternary volcanic activity K-Ar dating Chilean Patagonia Ridge subduction Southern Volcanic Zone Austral Volcanic Zone Hudson volcano Lautaro volcano Caldera Unspiked method
spellingShingle	Quaternary volcanic activity K-Ar dating Chilean Patagonia Ridge subduction Southern Volcanic Zone Austral Volcanic Zone Hudson volcano Lautaro volcano Caldera Unspiked method Orihashi,Yuji Naranjo,José A. Motoki,Akihisa Sumino,Hirochika Hirata,Daiji Anma,Ryo Nagao,Keisuke Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar ages
description	Twenty-nine K-Ar ages for lavas and juvenile ejecta obtained from Hudson volcano in the southern end of the Southern Volcanic Zone and Lautaro volcano in the northern end of the Austral Volcanic Zone, which are separated by a 350 km-long volcanic gap near the Chile ridge subduction zone, were determined using unspiked method that has significant sensitivity for dating young rocks (<0.1 Ma). It is newly revealed that Hudson is a significantly long-lived volcano; its activity started at ca. 1.0 Ma and continues to the Recent. The Hudson volcano has a well-preserved summit caldera complex of approximately 10 km in diameter, previously thought to be formed by a single event during the Holocene, perhaps at 6700 years BP. Our results for the K-Ar dating, however, indicate that the northeastern and southeastern flanks of the volcano formed at different times; formation of NE flank preceded that of SE flank. Aero-photographic observations indicate the presence of two or even three caldera rims. These data suggest that the Hudson volcano had a complex evolution, superimposing or partially nesting calderas rather than a simple caldera. The activity of the Lautaro volcano, began at ca. 0.17 Ma and has continued to the Recent, as it is indicated by our K-Ar first results. Though Lautaro volcano is a relatively large stratovolcano for Chilean Patagonia, the chemical and radiometric results indicate a narrow range in its variability when compared with those of the Hudson volcano. These narrow compositional and geochronological ranges suggest that the Lautaro volcano developed from a homogeneous magma chamber produced by slab melting during the late Quaternary, assuming that the sampled part of this heavily ice-mantled volcano, spans its full lifetime
author	Orihashi,Yuji Naranjo,José A. Motoki,Akihisa Sumino,Hirochika Hirata,Daiji Anma,Ryo Nagao,Keisuke
author_facet	Orihashi,Yuji Naranjo,José A. Motoki,Akihisa Sumino,Hirochika Hirata,Daiji Anma,Ryo Nagao,Keisuke
author_sort	Orihashi,Yuji
title	Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar ages
title_short	Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar ages
title_full	Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar ages
title_fullStr	Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar ages
title_full_unstemmed	Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar ages
title_sort	quaternary volcanic activity of hudson and lautaro volcanoes, chilean patagonia: new constraints from k-ar ages
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2004
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082004000200002
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Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: New constraints from K-Ar ages

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