Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile

Eighteen new radiometric ages (fourteen 40Ar-39Ar, four K-Ar), combined with previously published ages, confirm the existence of three main extensional back-arc volcanic events, previously defined by stratigraphic relationships, in Chilean Patagonia (Aysén region). These three events developed durin...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Parada,Miguel A., Lahsen,Alfredo, Palacios,Carlos
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2001
Materias:	Back-arc volcanism 40Ar-39Ar ages Magma source Crustal extension Chilean Patagonia
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082001000100002
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:scielo:S0716-02082001000100002
record_format	dspace
spelling	oai:scielo:S0716-020820010001000022001-11-07Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, ChileParada,Miguel A.Lahsen,AlfredoPalacios,Carlos Back-arc volcanism 40Ar-39Ar ages Magma source Crustal extension Chilean Patagonia Eighteen new radiometric ages (fourteen 40Ar-39Ar, four K-Ar), combined with previously published ages, confirm the existence of three main extensional back-arc volcanic events, previously defined by stratigraphic relationships, in Chilean Patagonia (Aysén region). These three events developed during the Middle Jurassic -Early Cretaceous (160-130 Ma). Cretaceous (114-75 Ma), and Eocene (55-46 Ma). Based on distinct geochemical data and Sr-Nd isotopic characteristics of the back-arc volcanic rocks collected north and south of 46°30'S, two Mesozoic-Eocene magmatic domains are recognized: Northern Magmatic Domain (NMD) and Southern Magmatic Domain (SMD). Most analyzed basalts and intermediate volcanic rocks of the NMD have alkaline affinities and depleted to slightly depleted Sr-Nd isotopic values similar to those derived from an asthenosphere-dominated source. The SMD mafic volcanic rocks have a subalkaline character and more enriched Sr-Nd isotopic signatures, comparable to those derived from a lithospheric source. The felsic volcanic rocks of the SMD have lower eNd values and slightly higher initial 87Sr/86Sr ratios than the NMD felsic rocks, suggesting a larger crustal contribution in the magma sources. The geochemical and isotopic distinction between NMD and SMD felsic rocks could be influenced by the presence of Paleozoic metamorphic rocks as basement of the volcanic rocks of the SMD. Moreover, the compositional distinction between basalts of both domains may correspond to differences in magnitude of extension, the NMD being the one where the extension would have been greater and, consequently, the lithosphere thinnerinfo:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Revista geológica de Chile v.28 n.1 20012001-07-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082001000100002en10.4067/S0716-02082001000100002
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Back-arc volcanism 40Ar-39Ar ages Magma source Crustal extension Chilean Patagonia
spellingShingle	Back-arc volcanism 40Ar-39Ar ages Magma source Crustal extension Chilean Patagonia Parada,Miguel A. Lahsen,Alfredo Palacios,Carlos Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile
description	Eighteen new radiometric ages (fourteen 40Ar-39Ar, four K-Ar), combined with previously published ages, confirm the existence of three main extensional back-arc volcanic events, previously defined by stratigraphic relationships, in Chilean Patagonia (Aysén region). These three events developed during the Middle Jurassic -Early Cretaceous (160-130 Ma). Cretaceous (114-75 Ma), and Eocene (55-46 Ma). Based on distinct geochemical data and Sr-Nd isotopic characteristics of the back-arc volcanic rocks collected north and south of 46°30'S, two Mesozoic-Eocene magmatic domains are recognized: Northern Magmatic Domain (NMD) and Southern Magmatic Domain (SMD). Most analyzed basalts and intermediate volcanic rocks of the NMD have alkaline affinities and depleted to slightly depleted Sr-Nd isotopic values similar to those derived from an asthenosphere-dominated source. The SMD mafic volcanic rocks have a subalkaline character and more enriched Sr-Nd isotopic signatures, comparable to those derived from a lithospheric source. The felsic volcanic rocks of the SMD have lower eNd values and slightly higher initial 87Sr/86Sr ratios than the NMD felsic rocks, suggesting a larger crustal contribution in the magma sources. The geochemical and isotopic distinction between NMD and SMD felsic rocks could be influenced by the presence of Paleozoic metamorphic rocks as basement of the volcanic rocks of the SMD. Moreover, the compositional distinction between basalts of both domains may correspond to differences in magnitude of extension, the NMD being the one where the extension would have been greater and, consequently, the lithosphere thinner
author	Parada,Miguel A. Lahsen,Alfredo Palacios,Carlos
author_facet	Parada,Miguel A. Lahsen,Alfredo Palacios,Carlos
author_sort	Parada,Miguel A.
title	Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile
title_short	Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile
title_full	Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile
title_fullStr	Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile
title_full_unstemmed	Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile
title_sort	ages and geochemistry of mesozoic-eocene back-arc volcanic rocks in the aysén region of the patagonian andes, chile
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2001
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082001000100002
work_keys_str_mv	AT paradamiguela agesandgeochemistryofmesozoiceocenebackarcvolcanicrocksintheaysenregionofthepatagonianandeschile AT lahsenalfredo agesandgeochemistryofmesozoiceocenebackarcvolcanicrocksintheaysenregionofthepatagonianandeschile AT palacioscarlos agesandgeochemistryofmesozoiceocenebackarcvolcanicrocksintheaysenregionofthepatagonianandeschile
_version_	1718439407084634112

Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile

Ejemplares similares