Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina

The Las Lozas volcanic sequence, which crops out at northwestern border of the Famatina belt-southeastern Puna, NW Argentina, is constituted mainly by rhyolites and a lesser volume of basalts and trachytes, and volcanoclastic deposits. These rocks, previously considered of Early Paleozoic age, are n...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Coira,Beatriz, Cisterna,Clara E, Ulbrich,Horstpeter H, Cordani,Umberto G
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2016
Materias:	Carboniferous post-orogenic volcanism Geochemistry Sr-Nd isotopes Northwestern Argentina
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062016000100006
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:scielo:S0718-71062016000100006
record_format	dspace
spelling	oai:scielo:S0718-710620160001000062016-07-29Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, ArgentinaCoira,BeatrizCisterna,Clara EUlbrich,Horstpeter HCordani,Umberto G Carboniferous post-orogenic volcanism Geochemistry Sr-Nd isotopes Northwestern Argentina The Las Lozas volcanic sequence, which crops out at northwestern border of the Famatina belt-southeastern Puna, NW Argentina, is constituted mainly by rhyolites and a lesser volume of basalts and trachytes, and volcanoclastic deposits. These rocks, previously considered of Early Paleozoic age, are now assigned to the Lower Pennsylvanian (320 Ma U-Pb age). They represent a bimodal volcanic succession that plot in the subalkaline/tholeiitic (rhyolites), alkaline basalts (basalts) and alkaline (trachytes) fields on the total alkali-silica diagram. The basalts display features comparable to transitional MORB and within-plate tholeiites, with contributions from a mantle source affected by crustal contamination. The acid members also show geochemical affinities to within-plate magmas, and their composition suggest a derivation from continental crustal material with mantle source interaction or a juvenile essentially mantle derived crust. The 320 Ma age from the Las Lozas volcanic succession as well as the 342 and 348 Ma U-Pb ages, from rocks in the nearby Cazadero Grande section, to the south, and the U-Pb ages from Sierra Pampeanas granites (332-357 Ma) highlight the importance achieved by Carboniferous magmatic activity in that region, framed between 320 and 350 Ma. Low strontium initial ratios from the Las Lozas (0.70479-0.70164) indicate a predominant contribution by a juvenile component, while the ratios in the nearby Cazadero Grande (0.71433-0.71233) and Sierras Pampeanas granites (0.717 to 0.7124) point to an input by enriched sources with restricted contribution of a mantle component. Nd isotopes from a basalt from the Las Lozas section (εNd(320) with +3.11, T DM with 774.6 Ma) indicates a possible asthenospheric source, with evidence for some mixture between juvenile and reworked crustal material. In contrast Sr-Nd isotopes in a rhyolite from Cazadero Grande (εNd(t) of -2.91 and -0.3, T DM of 1.09 and 1.1 Ga) and of Sierra Pampeanas granites (εNd(t) of -0.6, T DM of 1.19 and 1.1 Ga) suggest a crustal source with minor juvenile input. Taking in account the age difference in the region between Mississippian and the Lower Pennsylvanian magmatism, this would indicate a change in the magma source consistent with a more pronounced extensional tectonic regime for the Lower Pennsylvanian. This assumption need to be considered together with observations along a transect at 27°30'S, where the Carboniferous Eastern Sierras Pampeanas granitic rocks show, regardless of age, a greater contribution ofjuvenile material of mantle character to the west. Among these rocks, with a major juvenile component, are those of the Las Lozas succession as well the Cerro Gloria Granite, the eastern manifestations of the Carboniferous Eastern Sierras Pampeanas magmatism. From the foregoing emerges that the contribution of juvenile material could be continuously varied in the region through the Carboniferous, due to varying lithospheric extension. An example of this arise from the presented data of the Lozas succession, which indicate that this rocks resulted from reworking of supra-crustal material with input of juvenile magmas, linked to the change in the lithospheric extension.info:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Andean geology v.43 n.1 20162016-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062016000100006en10.5027/andgeoV43n1-a06
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Carboniferous post-orogenic volcanism Geochemistry Sr-Nd isotopes Northwestern Argentina
spellingShingle	Carboniferous post-orogenic volcanism Geochemistry Sr-Nd isotopes Northwestern Argentina Coira,Beatriz Cisterna,Clara E Ulbrich,Horstpeter H Cordani,Umberto G Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina
description	The Las Lozas volcanic sequence, which crops out at northwestern border of the Famatina belt-southeastern Puna, NW Argentina, is constituted mainly by rhyolites and a lesser volume of basalts and trachytes, and volcanoclastic deposits. These rocks, previously considered of Early Paleozoic age, are now assigned to the Lower Pennsylvanian (320 Ma U-Pb age). They represent a bimodal volcanic succession that plot in the subalkaline/tholeiitic (rhyolites), alkaline basalts (basalts) and alkaline (trachytes) fields on the total alkali-silica diagram. The basalts display features comparable to transitional MORB and within-plate tholeiites, with contributions from a mantle source affected by crustal contamination. The acid members also show geochemical affinities to within-plate magmas, and their composition suggest a derivation from continental crustal material with mantle source interaction or a juvenile essentially mantle derived crust. The 320 Ma age from the Las Lozas volcanic succession as well as the 342 and 348 Ma U-Pb ages, from rocks in the nearby Cazadero Grande section, to the south, and the U-Pb ages from Sierra Pampeanas granites (332-357 Ma) highlight the importance achieved by Carboniferous magmatic activity in that region, framed between 320 and 350 Ma. Low strontium initial ratios from the Las Lozas (0.70479-0.70164) indicate a predominant contribution by a juvenile component, while the ratios in the nearby Cazadero Grande (0.71433-0.71233) and Sierras Pampeanas granites (0.717 to 0.7124) point to an input by enriched sources with restricted contribution of a mantle component. Nd isotopes from a basalt from the Las Lozas section (εNd(320) with +3.11, T DM with 774.6 Ma) indicates a possible asthenospheric source, with evidence for some mixture between juvenile and reworked crustal material. In contrast Sr-Nd isotopes in a rhyolite from Cazadero Grande (εNd(t) of -2.91 and -0.3, T DM of 1.09 and 1.1 Ga) and of Sierra Pampeanas granites (εNd(t) of -0.6, T DM of 1.19 and 1.1 Ga) suggest a crustal source with minor juvenile input. Taking in account the age difference in the region between Mississippian and the Lower Pennsylvanian magmatism, this would indicate a change in the magma source consistent with a more pronounced extensional tectonic regime for the Lower Pennsylvanian. This assumption need to be considered together with observations along a transect at 27°30'S, where the Carboniferous Eastern Sierras Pampeanas granitic rocks show, regardless of age, a greater contribution ofjuvenile material of mantle character to the west. Among these rocks, with a major juvenile component, are those of the Las Lozas succession as well the Cerro Gloria Granite, the eastern manifestations of the Carboniferous Eastern Sierras Pampeanas magmatism. From the foregoing emerges that the contribution of juvenile material could be continuously varied in the region through the Carboniferous, due to varying lithospheric extension. An example of this arise from the presented data of the Lozas succession, which indicate that this rocks resulted from reworking of supra-crustal material with input of juvenile magmas, linked to the change in the lithospheric extension.
author	Coira,Beatriz Cisterna,Clara E Ulbrich,Horstpeter H Cordani,Umberto G
author_facet	Coira,Beatriz Cisterna,Clara E Ulbrich,Horstpeter H Cordani,Umberto G
author_sort	Coira,Beatriz
title	Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina
title_short	Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina
title_full	Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina
title_fullStr	Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina
title_full_unstemmed	Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina
title_sort	extensional carboniferous magmatism at the western margin of gondwana: las lozas valley, catamarca, argentina
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2016
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062016000100006
work_keys_str_mv	AT coirabeatriz extensionalcarboniferousmagmatismatthewesternmarginofgondwanalaslozasvalleycatamarcaargentina AT cisternaclarae extensionalcarboniferousmagmatismatthewesternmarginofgondwanalaslozasvalleycatamarcaargentina AT ulbrichhorstpeterh extensionalcarboniferousmagmatismatthewesternmarginofgondwanalaslozasvalleycatamarcaargentina AT cordaniumbertog extensionalcarboniferousmagmatismatthewesternmarginofgondwanalaslozasvalleycatamarcaargentina
_version_	1714205851990884352

Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina

Ejemplares similares