Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary : Was mélange melting involved?

This study of Sr-Nd initial isotopic ratios of plutons from the North Patagonian batholith (Argentina and Chile) revealed that a secular evolution spanning 180 m.y., from the Jurassic to Neogene, can be established in terms of magma sources, which in turn are correlated with changes in the tectonic...

Descripción completa

Guardado en:
Detalles Bibliográficos
Autores principales: Castro, Antonio, Rodríguez, Carmen Cristófol, Fernández, Carlos, Aragón, Eugenio, Pereira, Manuel Francisco, Molina, José F.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2021
Materias:
Ciencias Naturales
Geología
Magma
Mélange
Tectonic regime
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/123430
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-123430
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Naturales
Geología
Magma
Mélange
Tectonic regime
spellingShingle Ciencias Naturales
Geología
Magma
Mélange
Tectonic regime
Castro, Antonio
Rodríguez, Carmen Cristófol
Fernández, Carlos
Aragón, Eugenio
Pereira, Manuel Francisco
Molina, José F.
Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary : Was mélange melting involved?
topic_facet Ciencias Naturales
Geología
Magma
Mélange
Tectonic regime
description This study of Sr-Nd initial isotopic ratios of plutons from the North Patagonian batholith (Argentina and Chile) revealed that a secular evolution spanning 180 m.y., from the Jurassic to Neogene, can be established in terms of magma sources, which in turn are correlated with changes in the tectonic regime. The provenance and composition of end-member components in the source of magmas are represented by the Sr-Nd initial isotopic ratios (<sup>87</sup>Sr/<sup>86</sup>Sr and <sup>143</sup>Nd/<sup>144</sup>Nd) of the plutonic rocks. Our results support the interpretation that source composition was determined by incorporation of varied crustal materials and trench sediments via subduction erosion and sediment subduction into a subduction channel mélange. Subsequent melting of subducted mélanges at mantle depths and eventual reaction with the ultramafic mantle are proposed as the main causes of batholith magma generation, which was favored during periods of fast convergence and high obliquity between the involved plates. We propose that a parental diorite (= andesite) precursor arrived at the lower arc crust, where it underwent fractionation to yield the silicic melts (granodiorites and granites) that formed the batholiths. The diorite precursor could have been in turn fractionated from a more mafic melt of basaltic andesite composition, which was formed within the mantle by complete reaction of the bulk mélanges and the peridotite. Our proposal follows model predictions on the formation of mélange diapirs that carry fertile subducted materials into hot regions of the suprasubduction mantle wedge, where mafic parental magmas of batholiths originate. This model not only accounts for the secular geochemical variations of Andean batholiths, but it also avoids a fundamental paradox of the classical basalt model: the absence of ultramafic cumulates in the lower arc crust and in the continental crust in general.
format Articulo
Articulo
author Castro, Antonio
Rodríguez, Carmen Cristófol
Fernández, Carlos
Aragón, Eugenio
Pereira, Manuel Francisco
Molina, José F.
author_facet Castro, Antonio
Rodríguez, Carmen Cristófol
Fernández, Carlos
Aragón, Eugenio
Pereira, Manuel Francisco
Molina, José F.
author_sort Castro, Antonio
title Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary : Was mélange melting involved?
title_short Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary : Was mélange melting involved?
title_full Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary : Was mélange melting involved?
title_fullStr Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary : Was mélange melting involved?
title_full_unstemmed Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary : Was mélange melting involved?
title_sort secular variations of magma source compositions in the north patagonian batholith from the jurassic to tertiary : was mélange melting involved?
publishDate 2021
url http://sedici.unlp.edu.ar/handle/10915/123430
work_keys_str_mv AT castroantonio secularvariationsofmagmasourcecompositionsinthenorthpatagonianbatholithfromthejurassictotertiarywasmelangemeltinginvolved
AT rodriguezcarmencristofol secularvariationsofmagmasourcecompositionsinthenorthpatagonianbatholithfromthejurassictotertiarywasmelangemeltinginvolved
AT fernandezcarlos secularvariationsofmagmasourcecompositionsinthenorthpatagonianbatholithfromthejurassictotertiarywasmelangemeltinginvolved
AT aragoneugenio secularvariationsofmagmasourcecompositionsinthenorthpatagonianbatholithfromthejurassictotertiarywasmelangemeltinginvolved
AT pereiramanuelfrancisco secularvariationsofmagmasourcecompositionsinthenorthpatagonianbatholithfromthejurassictotertiarywasmelangemeltinginvolved
AT molinajosef secularvariationsofmagmasourcecompositionsinthenorthpatagonianbatholithfromthejurassictotertiarywasmelangemeltinginvolved
bdutipo_str Repositorios
_version_ 1764820449483554817

Ejemplares similares