Evolution history of the crust underlying Cerro Pampa, Argentine Patagonia: Constraint from LA-ICPMS U-Pb ages for exotic zircons in the Mid-Miocene adakite

This paper newly reports results of LA-ICPMS U-Pb dating for 282 zircon crystals separated from a Middle Miocene adakite in Cerro Pampa, southern Argentine Patagonia. With the exception of one spot age, 174 of the U-Pb concordia ages are markedly older (>94 Ma) than the cooling ages of the adakit...

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Autores principales: Orihashi, Y., Anma, R., Motoki, A., Haller, M.J., Hirata, D., Iwano, H., Sumino, H., Ramos, V.A.
Formato: JOUR
Materias:
Adakite
Cerro Pampa
Crustal evolution
Geochronological fingerprint
LA-ICPMS
Patagonia
Zircon
adakite
age determination
batholith
crustal evolution
crustal structure
geochronology
Mesozoic
metamorphism
Miocene
Paleozoic
Pangaea
plutonic rock
uranium-lead dating
zircon
Andes
Argentina
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00167002_v47_n2_p235_Orihashi
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00167002_v47_n2_p235_Orihashi2023-10-03T14:14:36Z Evolution history of the crust underlying Cerro Pampa, Argentine Patagonia: Constraint from LA-ICPMS U-Pb ages for exotic zircons in the Mid-Miocene adakite Orihashi, Y. Anma, R. Motoki, A. Haller, M.J. Hirata, D. Iwano, H. Sumino, H. Ramos, V.A. Adakite Cerro Pampa Crustal evolution Geochronological fingerprint LA-ICPMS Patagonia Zircon adakite age determination batholith crustal evolution crustal structure geochronology Mesozoic metamorphism Miocene Paleozoic Pangaea plutonic rock uranium-lead dating zircon Andes Argentina Patagonia This paper newly reports results of LA-ICPMS U-Pb dating for 282 zircon crystals separated from a Middle Miocene adakite in Cerro Pampa, southern Argentine Patagonia. With the exception of one spot age, 174 of the U-Pb concordia ages are markedly older (>94 Ma) than the cooling ages of the adakite magma (ca. 12 Ma). The presence of numerous exotic zircon crystals indicates that the adakitic magma carries up information related to the crustal components during its ascent through the entire crust underneath Cerro Pampa. The obtained concordia ages of exotic zircons, 94-1335 Ma. are divisible into five groups having distinctive peaks on a population diagram. The first (94-125 Ma) and second age groups (125-145 Ma) correspond to the age of plutonic activities that formed the main body of the South Patagonian Batholith. The third to fifth groups respectively correspond to activities of the El Qumado-Ibañez volcanic complex (145-170 Ma), plutonic rocks scarcely exposed in Central Patagonia (170-200 Ma), and the Eastern Andean metamorphic complex of Late Paleozoic to Early Mesozoic ages (200-380 Ma). Our data suggest that the crust underneath Cerro Pampa was formed mostly after 380 Ma, the majority forming during the Early Cretaceous to Middle Jurassic. The processes of crustal development ceased for ca. 80 m.y. until the activity of the Cerro Pampa adakite in ca. 12 Ma. In contrast to the existence of numerous Archaean-Palaeoproterozoic exotic zircons in Mesozoic plutonic rocks distributed in Andean Cordillera at around 46°S. no evidence was found for Archaean-Paleoproterozoic crust on the Cerro Pampa región at 48°S. This evidence suggests that two crusts must have aggregated along a boundary between 46°S and 48°S with the continental margin of Gondwana during Late Paleozoic times, as part of the amalgamation of Pangea. Copyright © 2013 by The Geochemical Society of Japan. Fil:Haller, M.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Ramos, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00167002_v47_n2_p235_Orihashi
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Adakite
Cerro Pampa
Crustal evolution
Geochronological fingerprint
LA-ICPMS
Patagonia
Zircon
adakite
age determination
batholith
crustal evolution
crustal structure
geochronology
Mesozoic
metamorphism
Miocene
Paleozoic
Pangaea
plutonic rock
uranium-lead dating
zircon
Andes
Argentina
Patagonia
spellingShingle Adakite
Cerro Pampa
Crustal evolution
Geochronological fingerprint
LA-ICPMS
Patagonia
Zircon
adakite
age determination
batholith
crustal evolution
crustal structure
geochronology
Mesozoic
metamorphism
Miocene
Paleozoic
Pangaea
plutonic rock
uranium-lead dating
zircon
Andes
Argentina
Patagonia
Orihashi, Y.
Anma, R.
Motoki, A.
Haller, M.J.
Hirata, D.
Iwano, H.
Sumino, H.
Ramos, V.A.
Evolution history of the crust underlying Cerro Pampa, Argentine Patagonia: Constraint from LA-ICPMS U-Pb ages for exotic zircons in the Mid-Miocene adakite
topic_facet Adakite
Cerro Pampa
Crustal evolution
Geochronological fingerprint
LA-ICPMS
Patagonia
Zircon
adakite
age determination
batholith
crustal evolution
crustal structure
geochronology
Mesozoic
metamorphism
Miocene
Paleozoic
Pangaea
plutonic rock
uranium-lead dating
zircon
Andes
Argentina
Patagonia
description This paper newly reports results of LA-ICPMS U-Pb dating for 282 zircon crystals separated from a Middle Miocene adakite in Cerro Pampa, southern Argentine Patagonia. With the exception of one spot age, 174 of the U-Pb concordia ages are markedly older (>94 Ma) than the cooling ages of the adakite magma (ca. 12 Ma). The presence of numerous exotic zircon crystals indicates that the adakitic magma carries up information related to the crustal components during its ascent through the entire crust underneath Cerro Pampa. The obtained concordia ages of exotic zircons, 94-1335 Ma. are divisible into five groups having distinctive peaks on a population diagram. The first (94-125 Ma) and second age groups (125-145 Ma) correspond to the age of plutonic activities that formed the main body of the South Patagonian Batholith. The third to fifth groups respectively correspond to activities of the El Qumado-Ibañez volcanic complex (145-170 Ma), plutonic rocks scarcely exposed in Central Patagonia (170-200 Ma), and the Eastern Andean metamorphic complex of Late Paleozoic to Early Mesozoic ages (200-380 Ma). Our data suggest that the crust underneath Cerro Pampa was formed mostly after 380 Ma, the majority forming during the Early Cretaceous to Middle Jurassic. The processes of crustal development ceased for ca. 80 m.y. until the activity of the Cerro Pampa adakite in ca. 12 Ma. In contrast to the existence of numerous Archaean-Palaeoproterozoic exotic zircons in Mesozoic plutonic rocks distributed in Andean Cordillera at around 46°S. no evidence was found for Archaean-Paleoproterozoic crust on the Cerro Pampa región at 48°S. This evidence suggests that two crusts must have aggregated along a boundary between 46°S and 48°S with the continental margin of Gondwana during Late Paleozoic times, as part of the amalgamation of Pangea. Copyright © 2013 by The Geochemical Society of Japan.
format JOUR
author Orihashi, Y.
Anma, R.
Motoki, A.
Haller, M.J.
Hirata, D.
Iwano, H.
Sumino, H.
Ramos, V.A.
author_facet Orihashi, Y.
Anma, R.
Motoki, A.
Haller, M.J.
Hirata, D.
Iwano, H.
Sumino, H.
Ramos, V.A.
author_sort Orihashi, Y.
title Evolution history of the crust underlying Cerro Pampa, Argentine Patagonia: Constraint from LA-ICPMS U-Pb ages for exotic zircons in the Mid-Miocene adakite
title_short Evolution history of the crust underlying Cerro Pampa, Argentine Patagonia: Constraint from LA-ICPMS U-Pb ages for exotic zircons in the Mid-Miocene adakite
title_full Evolution history of the crust underlying Cerro Pampa, Argentine Patagonia: Constraint from LA-ICPMS U-Pb ages for exotic zircons in the Mid-Miocene adakite
title_fullStr Evolution history of the crust underlying Cerro Pampa, Argentine Patagonia: Constraint from LA-ICPMS U-Pb ages for exotic zircons in the Mid-Miocene adakite
title_full_unstemmed Evolution history of the crust underlying Cerro Pampa, Argentine Patagonia: Constraint from LA-ICPMS U-Pb ages for exotic zircons in the Mid-Miocene adakite
title_sort evolution history of the crust underlying cerro pampa, argentine patagonia: constraint from la-icpms u-pb ages for exotic zircons in the mid-miocene adakite
url http://hdl.handle.net/20.500.12110/paper_00167002_v47_n2_p235_Orihashi
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