Mid-Cenozoic SHRIMP U-Pb detrital zircon ages from metasedimentary rocks in the North Patagonian Andes of Aysén, Chile
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...
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| Autores principales: | , , , , , , , |
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| Lenguaje: | English |
| Publicado: |
Servicio Nacional de Geología y Minería (SERNAGEOMIN)
2021
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| Materias: | |
| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062021000100054 |
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| Sumario: | 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. |
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