Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30'-37°S), Argentina

A series of mesosilicic volcanic centers have been studied on the San Rafael Block (SRB), 300 km to the east of the present-day volcanic arc. K-Ar ages indicate that this magmatic activity was developed in at least two stages: the older volcanic centers (~15-10 Ma) are located in the central and wes...

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Detalles Bibliográficos
Publicado: 2015
Materias:
Andesitic volcanism
Back-arc
Geochemistry
San Rafael Block
Shallow subduction
backarc basin
calc alkaline rock
Cenozoic
geochemistry
island arc
Miocene
Pliocene
subduction zone
volcanism
Argentina
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v64_n_p365_Litvak
http://hdl.handle.net/20.500.12110/paper_08959811_v64_n_p365_Litvak
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_08959811_v64_n_p365_Litvak
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spelling paper:paper_08959811_v64_n_p365_Litvak2023-06-08T15:48:50Z Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30'-37°S), Argentina Andesitic volcanism Back-arc Geochemistry San Rafael Block Shallow subduction backarc basin calc alkaline rock Cenozoic geochemistry island arc Miocene Pliocene subduction zone volcanism Argentina A series of mesosilicic volcanic centers have been studied on the San Rafael Block (SRB), 300 km to the east of the present-day volcanic arc. K-Ar ages indicate that this magmatic activity was developed in at least two stages: the older volcanic centers (~15-10 Ma) are located in the central and westernmost part of the SRB (around 36°S and 69°W) and the younger centers (8-3.5 Ma) are located in an eastern position (around 36°S and 69°30'W) with respect to the older group. These volcanic rocks have andesitic to dacitic compositions and correspond to a high-K calc-alkaline sequence as shown by their SiO2, K2O and FeO/MgO contents. Elevated Ba/La, Ba/Ta and La/Ta ratios show an arc-like signature, and primitive mantle normalized trace element diagrams show typical depletions of high field strength elements (HFSE) relative to large ion lithophile elements (LILE). Rare earth element (REE) patterns suggest pyroxene and amphibole crystallization. Geochemical data obtained for SRB volcanic rocks support the proposal for a shallow subduction zone for the latest Miocene between 34°30″-37°S. Regionally, SRB volcanism is associated with a mid-Miocene to early Pliocene eastward arc migration caused by the shallowing of the subducting slab in the South-Central Andes at these latitudes, which represents the evolution of the Payenia shallow subduction segment. Overall, middle Miocene to early Pliocene volcanism located in the Payenia back-arc shows evidence for the influence of slab-related components. The younger (8-3.5 Ma) San Rafael volcanic rocks indicate the maximum slab shallowing and the easternmost extent of slab influence in the back-arc. © 2015 Elsevier Ltd. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v64_n_p365_Litvak http://hdl.handle.net/20.500.12110/paper_08959811_v64_n_p365_Litvak
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Andesitic volcanism
Back-arc
Geochemistry
San Rafael Block
Shallow subduction
backarc basin
calc alkaline rock
Cenozoic
geochemistry
island arc
Miocene
Pliocene
subduction zone
volcanism
Argentina
spellingShingle Andesitic volcanism
Back-arc
Geochemistry
San Rafael Block
Shallow subduction
backarc basin
calc alkaline rock
Cenozoic
geochemistry
island arc
Miocene
Pliocene
subduction zone
volcanism
Argentina
Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30'-37°S), Argentina
topic_facet Andesitic volcanism
Back-arc
Geochemistry
San Rafael Block
Shallow subduction
backarc basin
calc alkaline rock
Cenozoic
geochemistry
island arc
Miocene
Pliocene
subduction zone
volcanism
Argentina
description A series of mesosilicic volcanic centers have been studied on the San Rafael Block (SRB), 300 km to the east of the present-day volcanic arc. K-Ar ages indicate that this magmatic activity was developed in at least two stages: the older volcanic centers (~15-10 Ma) are located in the central and westernmost part of the SRB (around 36°S and 69°W) and the younger centers (8-3.5 Ma) are located in an eastern position (around 36°S and 69°30'W) with respect to the older group. These volcanic rocks have andesitic to dacitic compositions and correspond to a high-K calc-alkaline sequence as shown by their SiO2, K2O and FeO/MgO contents. Elevated Ba/La, Ba/Ta and La/Ta ratios show an arc-like signature, and primitive mantle normalized trace element diagrams show typical depletions of high field strength elements (HFSE) relative to large ion lithophile elements (LILE). Rare earth element (REE) patterns suggest pyroxene and amphibole crystallization. Geochemical data obtained for SRB volcanic rocks support the proposal for a shallow subduction zone for the latest Miocene between 34°30″-37°S. Regionally, SRB volcanism is associated with a mid-Miocene to early Pliocene eastward arc migration caused by the shallowing of the subducting slab in the South-Central Andes at these latitudes, which represents the evolution of the Payenia shallow subduction segment. Overall, middle Miocene to early Pliocene volcanism located in the Payenia back-arc shows evidence for the influence of slab-related components. The younger (8-3.5 Ma) San Rafael volcanic rocks indicate the maximum slab shallowing and the easternmost extent of slab influence in the back-arc. © 2015 Elsevier Ltd.
title Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30'-37°S), Argentina
title_short Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30'-37°S), Argentina
title_full Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30'-37°S), Argentina
title_fullStr Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30'-37°S), Argentina
title_full_unstemmed Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30'-37°S), Argentina
title_sort late cenozoic calc-alkaline volcanism over the payenia shallow subduction zone, south-central andean back-arc (34°30'-37°s), argentina
publishDate 2015
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v64_n_p365_Litvak
http://hdl.handle.net/20.500.12110/paper_08959811_v64_n_p365_Litvak
_version_ 1768543090302255104

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