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 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.

Bibliographic Details

Main Authors:	Quezada,Paulo, Hervé,Francisco, Calderón,Mauricio, Fanning,Mark, Pankhurst,Robert, Godoy,Estanislao, Urbina,Octavio, Suárez,Rodrigo
Format:	Digital revista
Language:	English
Published:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2021
Online Access:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062021000100054
Tags:	Add Tag No Tags, Be the first to tag this record!