Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics

Four Middle-to-Late Miocene barren plutonic complexes that occur between the giant porphyry copper deposits of the central Chilean Andes were selected for U-Pb LA-ICPMS geochronology and Hf-isotope systematics on single zircon grains. Major and trace elements and Sr-Nd-Hf isotope whole rock geochemi...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Deckart,Katja, Godoy,Estanislao, Bertens,Alfredo, Jerez,Daniela, Saeed,Ayesha
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2010
Materias:	Magmatism Miocene Central Andes Nd-Hf and U-Pb isotopes
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062010000100001
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:scielo:S0718-71062010000100001
record_format	dspace
spelling	oai:scielo:S0718-710620100001000012010-04-14Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematicsDeckart,KatjaGodoy,EstanislaoBertens,AlfredoJerez,DanielaSaeed,Ayesha Magmatism Miocene Central Andes Nd-Hf and U-Pb isotopes Four Middle-to-Late Miocene barren plutonic complexes that occur between the giant porphyry copper deposits of the central Chilean Andes were selected for U-Pb LA-ICPMS geochronology and Hf-isotope systematics on single zircon grains. Major and trace elements and Sr-Nd-Hf isotope whole rock geochemical studies were under-taken to compare with slightly younger or coeval barren and fertile intrusive rocks between 32° and 34°S. The studied granitoids yield resolvable crystallization ages of 11.3±0.1 Ma (Cerro Mesón Alto massif), 10.3±0.2 Ma (La Gloria pluton), 14.9±0.2 Ma/14.9±0.1 Ma (Yerba Loca stock) and 11.2±0.1 Ma/14.7±0.1 Ma (San Francisco Batholith). Major and trace elements discard an adakitic signature as suggested for coeval porphyric intrusions at 32°S, slightly younger mineralized porphyries at Río Blanco-Los Bronces deposit and other Cenozoic adakites. Volcanic host rocks are less fractionated than the intrusive rock units. The same observation can be made for the unmineralized northern plutons compared to the southern ones. Initial Sr-Nd isotope data show insignificant variation (0.703761-0.704118 and 0.512758-0.512882), plotting in the mantle array. Trace element enrichment can be explained by addition of subducted-slab fluids and/or terrigenous sediments to the mantle wedge prior to and/or slight crustal input during magma ascent. Zircon grains separated from these barren intrusives share a similar initial εHf i-data variation for the younger age group (10-12 Ma; 7.04-9.54) and show a more scattered range for the older one (14-15 Ma; 8.50-15.34); both sets plot between the DM and CLTUR evolution lines. There is evidence that magma evolution was slightly distinct through time from older to younger barren magmatism, compared to a few fertile porphyritic rocks from Río Blanco-Los Bronces porphyry copper deposit. It is suggested that chronological inconsistencies within these complexes might be related to differential shortening across the NE-SW-trending Yeso Valley transfer fault, assumed as coeval, which also explains the local lack of easterly magmatic are front migration.info:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Andean geology v.37 n.1 20102010-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062010000100001en10.4067/S0718-71062010000100001
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Magmatism Miocene Central Andes Nd-Hf and U-Pb isotopes
spellingShingle	Magmatism Miocene Central Andes Nd-Hf and U-Pb isotopes Deckart,Katja Godoy,Estanislao Bertens,Alfredo Jerez,Daniela Saeed,Ayesha Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics
description	Four Middle-to-Late Miocene barren plutonic complexes that occur between the giant porphyry copper deposits of the central Chilean Andes were selected for U-Pb LA-ICPMS geochronology and Hf-isotope systematics on single zircon grains. Major and trace elements and Sr-Nd-Hf isotope whole rock geochemical studies were under-taken to compare with slightly younger or coeval barren and fertile intrusive rocks between 32° and 34°S. The studied granitoids yield resolvable crystallization ages of 11.3±0.1 Ma (Cerro Mesón Alto massif), 10.3±0.2 Ma (La Gloria pluton), 14.9±0.2 Ma/14.9±0.1 Ma (Yerba Loca stock) and 11.2±0.1 Ma/14.7±0.1 Ma (San Francisco Batholith). Major and trace elements discard an adakitic signature as suggested for coeval porphyric intrusions at 32°S, slightly younger mineralized porphyries at Río Blanco-Los Bronces deposit and other Cenozoic adakites. Volcanic host rocks are less fractionated than the intrusive rock units. The same observation can be made for the unmineralized northern plutons compared to the southern ones. Initial Sr-Nd isotope data show insignificant variation (0.703761-0.704118 and 0.512758-0.512882), plotting in the mantle array. Trace element enrichment can be explained by addition of subducted-slab fluids and/or terrigenous sediments to the mantle wedge prior to and/or slight crustal input during magma ascent. Zircon grains separated from these barren intrusives share a similar initial εHf i-data variation for the younger age group (10-12 Ma; 7.04-9.54) and show a more scattered range for the older one (14-15 Ma; 8.50-15.34); both sets plot between the DM and CLTUR evolution lines. There is evidence that magma evolution was slightly distinct through time from older to younger barren magmatism, compared to a few fertile porphyritic rocks from Río Blanco-Los Bronces porphyry copper deposit. It is suggested that chronological inconsistencies within these complexes might be related to differential shortening across the NE-SW-trending Yeso Valley transfer fault, assumed as coeval, which also explains the local lack of easterly magmatic are front migration.
author	Deckart,Katja Godoy,Estanislao Bertens,Alfredo Jerez,Daniela Saeed,Ayesha
author_facet	Deckart,Katja Godoy,Estanislao Bertens,Alfredo Jerez,Daniela Saeed,Ayesha
author_sort	Deckart,Katja
title	Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics
title_short	Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics
title_full	Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics
title_fullStr	Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics
title_full_unstemmed	Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics
title_sort	barren miocene granitoids in the central andean metallogenic belt, chile: geochemistry and nd-hf and u-pb isotope systematics
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2010
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062010000100001
work_keys_str_mv	AT deckartkatja barrenmiocenegranitoidsinthecentralandeanmetallogenicbeltchilegeochemistryandndhfandupbisotopesystematics AT godoyestanislao barrenmiocenegranitoidsinthecentralandeanmetallogenicbeltchilegeochemistryandndhfandupbisotopesystematics AT bertensalfredo barrenmiocenegranitoidsinthecentralandeanmetallogenicbeltchilegeochemistryandndhfandupbisotopesystematics AT jerezdaniela barrenmiocenegranitoidsinthecentralandeanmetallogenicbeltchilegeochemistryandndhfandupbisotopesystematics AT saeedayesha barrenmiocenegranitoidsinthecentralandeanmetallogenicbeltchilegeochemistryandndhfandupbisotopesystematics
_version_	1714205826477981696

Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics

Ejemplares similares