Mid-cenozoic shrimp u-pb detrital zircon ages from metasedimentary rocks in the north Patagonian andes of Aysén, Chile

Paulo Quezada; Francisco Hervé; Mauricio Calderón; Mark Fanning; Robert Pankhurst; Estanislao Godoy; Octavio Urbina; Rodrigo Suárez

doi:10.5027/andgeov48n1-3282

Mid-cenozoic shrimp u-pb detrital zircon ages from metasedimentary rocks in the north Patagonian andes of Aysén, Chile

Paulo Quezada^*, Francisco Hervé, Mauricio Calderón, Mark Fanning, Robert Pankhurst, Estanislao Godoy, Octavio Urbina, Rodrigo Suárez

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

Previously undated low-grade metamorphic rocks from the Puerto Cisnes-Queulat area (44°30’ S) contain detrital zircons of mid-Oligocene age (ca. 28 Ma). Their outcrops represent the easternmost occurrence of the late Oligocene to early Miocene marine volcano-sedimentary Traiguén Formation; previous correlation with the Paleozoic metamorphic basement of this sector of the North Patagonian Andes is thus refuted. A similar age and provenance were obtained for a paraconglomerate bed of the La Junta Formation ca. 80 km to the north, which is thought to represent a high-energy lateral facies variation of the Traiguén Formation. Miocene plutonic rocks of the North Patagonian Batholith intruded these metasedimentary rocks, generating a contact metamorphic aureole that reaches biotite grade and overprints a previous metamorphic fabric probably formed during closure of the Traiguén Basin. Similar young ages for metamorphic rocks located immediately west of the Liquiñe-Ofqui Fault Zone 300 km north, near Ayacara, suggest a regional pattern of earliest Neogene metamorphism and rapid exhumation in this segment of the Patagonian Andes.

Original language	English
Pages (from-to)	54-74
Number of pages	21
Journal	Andean Geology
Volume	48
Issue number	1
DOIs	https://doi.org/10.5027/andgeov48n1-3282
Publication status	Published - Jan 2021

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title = "Mid-cenozoic shrimp u-pb detrital zircon ages from metasedimentary rocks in the north Patagonian andes of Ays{\'e}n, Chile",

abstract = "Previously undated low-grade metamorphic rocks from the Puerto Cisnes-Queulat area (44°30{\textquoteright} S) contain detrital zircons of mid-Oligocene age (ca. 28 Ma). Their outcrops represent the easternmost occurrence of the late Oligocene to early Miocene marine volcano-sedimentary Traigu{\'e}n Formation; previous correlation with the Paleozoic metamorphic basement of this sector of the North Patagonian Andes is thus refuted. A similar age and provenance were obtained for a paraconglomerate bed of the La Junta Formation ca. 80 km to the north, which is thought to represent a high-energy lateral facies variation of the Traigu{\'e}n Formation. Miocene plutonic rocks of the North Patagonian Batholith intruded these metasedimentary rocks, generating a contact metamorphic aureole that reaches biotite grade and overprints a previous metamorphic fabric probably formed during closure of the Traigu{\'e}n Basin. Similar young ages for metamorphic rocks located immediately west of the Liqui{\~n}e-Ofqui Fault Zone 300 km north, near Ayacara, suggest a regional pattern of earliest Neogene metamorphism and rapid exhumation in this segment of the Patagonian Andes.",

keywords = "Liqui{\~n}e-Ofqui Fault Zone, Traigu{\'e}n Formation",

author = "Paulo Quezada and Francisco Herv{\'e} and Mauricio Calder{\'o}n and Mark Fanning and Robert Pankhurst and Estanislao Godoy and Octavio Urbina and Rodrigo Su{\'a}rez",

year = "2021",

month = jan,

doi = "10.5027/andgeov48n1-3282",

language = "English",

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pages = "54--74",

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AU - Quezada, Paulo

AU - Hervé, Francisco

AU - Calderón, Mauricio

AU - Fanning, Mark

AU - Pankhurst, Robert

AU - Godoy, Estanislao

AU - Urbina, Octavio

AU - Suárez, Rodrigo

PY - 2021/1

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N2 - Previously undated low-grade metamorphic rocks from the Puerto Cisnes-Queulat area (44°30’ S) contain detrital zircons of mid-Oligocene age (ca. 28 Ma). Their outcrops represent the easternmost occurrence of the late Oligocene to early Miocene marine volcano-sedimentary Traiguén Formation; previous correlation with the Paleozoic metamorphic basement of this sector of the North Patagonian Andes is thus refuted. A similar age and provenance were obtained for a paraconglomerate bed of the La Junta Formation ca. 80 km to the north, which is thought to represent a high-energy lateral facies variation of the Traiguén Formation. Miocene plutonic rocks of the North Patagonian Batholith intruded these metasedimentary rocks, generating a contact metamorphic aureole that reaches biotite grade and overprints a previous metamorphic fabric probably formed during closure of the Traiguén Basin. Similar young ages for metamorphic rocks located immediately west of the Liquiñe-Ofqui Fault Zone 300 km north, near Ayacara, suggest a regional pattern of earliest Neogene metamorphism and rapid exhumation in this segment of the Patagonian Andes.

AB - Previously undated low-grade metamorphic rocks from the Puerto Cisnes-Queulat area (44°30’ S) contain detrital zircons of mid-Oligocene age (ca. 28 Ma). Their outcrops represent the easternmost occurrence of the late Oligocene to early Miocene marine volcano-sedimentary Traiguén Formation; previous correlation with the Paleozoic metamorphic basement of this sector of the North Patagonian Andes is thus refuted. A similar age and provenance were obtained for a paraconglomerate bed of the La Junta Formation ca. 80 km to the north, which is thought to represent a high-energy lateral facies variation of the Traiguén Formation. Miocene plutonic rocks of the North Patagonian Batholith intruded these metasedimentary rocks, generating a contact metamorphic aureole that reaches biotite grade and overprints a previous metamorphic fabric probably formed during closure of the Traiguén Basin. Similar young ages for metamorphic rocks located immediately west of the Liquiñe-Ofqui Fault Zone 300 km north, near Ayacara, suggest a regional pattern of earliest Neogene metamorphism and rapid exhumation in this segment of the Patagonian Andes.

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KW - Traiguén Formation

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DO - 10.5027/andgeov48n1-3282

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Mid-cenozoic shrimp u-pb detrital zircon ages from metasedimentary rocks in the north Patagonian andes of Aysén, Chile

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