Patagonia-Antarctica Early Paleozoic conjugate margins: Cambrian synsedimentary silicic magmatism, U-Pb dating of K-bentonites, and related volcanogenic rocks

This study describes the stratigraphic features, petrology and geochemistry and geochronology constraints of K-bentonites, ignimbrites and related volcanogenic rocks interbedded in the marine sedimentary sequence of the El Jagüelito Formation from northern Patagonia basement, southwestern Gondwana m...

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Language:unknown
Published: 2018
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Online Access:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1342937X_v63_n_p186_Gonzalez
https://hdl.handle.net/20.500.12110/paper_1342937X_v63_n_p186_Gonzalez
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record_format openpolar
spelling ftunibueairesbd:paper:paper_1342937X_v63_n_p186_Gonzalez 2023-05-15T13:51:24+02:00 Patagonia-Antarctica Early Paleozoic conjugate margins: Cambrian synsedimentary silicic magmatism, U-Pb dating of K-bentonites, and related volcanogenic rocks 2018 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1342937X_v63_n_p186_Gonzalez https://hdl.handle.net/20.500.12110/paper_1342937X_v63_n_p186_Gonzalez unknown https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1342937X_v63_n_p186_Gonzalez http://hdl.handle.net/20.500.12110/paper_1342937X_v63_n_p186_Gonzalez Antarctica Cambrian magmatism Gondwana K-bentonite Patagonia U-Pb dating 2018 ftunibueairesbd https://doi.org/20.500.12110/paper_1342937X_v63_n_p186_Gonzalez 2023-02-16T02:09:35Z This study describes the stratigraphic features, petrology and geochemistry and geochronology constraints of K-bentonites, ignimbrites and related volcanogenic rocks interbedded in the marine sedimentary sequence of the El Jagüelito Formation from northern Patagonia basement, southwestern Gondwana margin (41°33′S-65°15′W, South America). Six SHRIMP and ICP-MS U-Pb zircon ages from pyroclastic and volcanogenic sedimentary rocks indicate two stages of synsedimentary volcanism at c. 530 and c. 515 Ma which constraint the whole volcano-sedimentary pile to Early-Middle Cambrian. Distal volcanic ash fall deposits of K-bentonites and proximal pyroclastic flows of ignimbrites were erupted from three subaerial to subaqueous eruptive centers and are associated with volcanogenic facies and sub-volcanic intrusive equivalents. The volcanic rocks were deposited synchronously with on-going dynamic siliciclastic sedimentation into an actively subsiding basin. Dacitic K-bentonites and high-silica rhyolitic ignimbrites belong to the same high-K calc-alkaline/shoshonitic magma series and have a similar peraluminous signature. Their HFSE patterns with relative depletion in Nb, Sr, P, and Ti and the LREE-enriched patterns with a negative Eu anomaly indicate characteristics of subduction-related magmas associated with active continental arc magmatism. The geochemical discrimination diagrams together with geological features suggest an extensional tectonic setting for K-rich magmas within the overall convergent-margin system. Silicic, more potassic magmas with the inherited subduction-related character of the El Jagüelito Formation erupted on a back-arc basin. Their volcanic rocks are products of a mixture of fractionated mafic magmas and partial crustal melts. The integration of the Cambrian synsedimentary explosive volcanism of the El Jagüelito Formation with coeval magmatism of northern Patagonia led the interpretation to the continental scale of the paleo-Pacific margin of Gondwana by Early Paleozoic. The El Jagüelito Formation ... Other/Unknown Material Antarc* Antarctica Biblioteca Digital FCEN-UBA (Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires) Pacific Patagonia
institution Open Polar
collection Biblioteca Digital FCEN-UBA (Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires)
op_collection_id ftunibueairesbd
language unknown
topic Antarctica
Cambrian magmatism
Gondwana
K-bentonite
Patagonia
U-Pb dating
spellingShingle Antarctica
Cambrian magmatism
Gondwana
K-bentonite
Patagonia
U-Pb dating
Patagonia-Antarctica Early Paleozoic conjugate margins: Cambrian synsedimentary silicic magmatism, U-Pb dating of K-bentonites, and related volcanogenic rocks
topic_facet Antarctica
Cambrian magmatism
Gondwana
K-bentonite
Patagonia
U-Pb dating
description This study describes the stratigraphic features, petrology and geochemistry and geochronology constraints of K-bentonites, ignimbrites and related volcanogenic rocks interbedded in the marine sedimentary sequence of the El Jagüelito Formation from northern Patagonia basement, southwestern Gondwana margin (41°33′S-65°15′W, South America). Six SHRIMP and ICP-MS U-Pb zircon ages from pyroclastic and volcanogenic sedimentary rocks indicate two stages of synsedimentary volcanism at c. 530 and c. 515 Ma which constraint the whole volcano-sedimentary pile to Early-Middle Cambrian. Distal volcanic ash fall deposits of K-bentonites and proximal pyroclastic flows of ignimbrites were erupted from three subaerial to subaqueous eruptive centers and are associated with volcanogenic facies and sub-volcanic intrusive equivalents. The volcanic rocks were deposited synchronously with on-going dynamic siliciclastic sedimentation into an actively subsiding basin. Dacitic K-bentonites and high-silica rhyolitic ignimbrites belong to the same high-K calc-alkaline/shoshonitic magma series and have a similar peraluminous signature. Their HFSE patterns with relative depletion in Nb, Sr, P, and Ti and the LREE-enriched patterns with a negative Eu anomaly indicate characteristics of subduction-related magmas associated with active continental arc magmatism. The geochemical discrimination diagrams together with geological features suggest an extensional tectonic setting for K-rich magmas within the overall convergent-margin system. Silicic, more potassic magmas with the inherited subduction-related character of the El Jagüelito Formation erupted on a back-arc basin. Their volcanic rocks are products of a mixture of fractionated mafic magmas and partial crustal melts. The integration of the Cambrian synsedimentary explosive volcanism of the El Jagüelito Formation with coeval magmatism of northern Patagonia led the interpretation to the continental scale of the paleo-Pacific margin of Gondwana by Early Paleozoic. The El Jagüelito Formation ...
title Patagonia-Antarctica Early Paleozoic conjugate margins: Cambrian synsedimentary silicic magmatism, U-Pb dating of K-bentonites, and related volcanogenic rocks
title_short Patagonia-Antarctica Early Paleozoic conjugate margins: Cambrian synsedimentary silicic magmatism, U-Pb dating of K-bentonites, and related volcanogenic rocks
title_full Patagonia-Antarctica Early Paleozoic conjugate margins: Cambrian synsedimentary silicic magmatism, U-Pb dating of K-bentonites, and related volcanogenic rocks
title_fullStr Patagonia-Antarctica Early Paleozoic conjugate margins: Cambrian synsedimentary silicic magmatism, U-Pb dating of K-bentonites, and related volcanogenic rocks
title_full_unstemmed Patagonia-Antarctica Early Paleozoic conjugate margins: Cambrian synsedimentary silicic magmatism, U-Pb dating of K-bentonites, and related volcanogenic rocks
title_sort patagonia-antarctica early paleozoic conjugate margins: cambrian synsedimentary silicic magmatism, u-pb dating of k-bentonites, and related volcanogenic rocks
publishDate 2018
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1342937X_v63_n_p186_Gonzalez
https://hdl.handle.net/20.500.12110/paper_1342937X_v63_n_p186_Gonzalez
geographic Pacific
Patagonia
geographic_facet Pacific
Patagonia
genre Antarc*
Antarctica
genre_facet Antarc*
Antarctica
op_relation https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1342937X_v63_n_p186_Gonzalez
http://hdl.handle.net/20.500.12110/paper_1342937X_v63_n_p186_Gonzalez
op_doi https://doi.org/20.500.12110/paper_1342937X_v63_n_p186_Gonzalez
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