The country rocks of devonian magmatism in the north patagonian massif and Chaitenia
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Fecha
2018-09
Profesor/a Guía
Facultad/escuela
Idioma
en
Título de la revista
ISSN de la revista
Título del volumen
Editor
Servicio Nacional de Geologia y Mineria
Nombre de Curso
Licencia CC
Licencia CC
Resumen
Previous work has shown that Devonian magmatism in the southern Andes occurred in two contemporaneous belts: one emplaced in the continental crust of the North Patagonian Massif and the other in an oceanic island arc terrane to the west, Chaitenia, which was later accreted to Patagonia. The country rocks of the plutonic rocks consist of metasedimentary complexes which crop out sporadically in the Andes on both sides of the Argentina-Chile border, and additionally of pillow metabasalts for Chaitenia. Detrital zircon SHRIMP U-Pb age determinations in 13 samples of these rocks indicate maximum possible depositional ages from ca. 370 to 900 Ma, and the case is argued for mostly Devonian sedimentation as for the fossiliferous Buill slates. Ordovician, Cambrian-late Neoproterozoic and “Grenville-age” provenance is seen throughout, except for the most westerly outcrops where Devonian detrital zircons predominate. Besides a difference in the Precambrian zircon grains, 76% versus 25% respectively, there is no systematic variation in provenance from the Patagonian foreland to Chaitenia, so that the island arc terrane must have been proximal to the continent: its deeper crust is not exposed but several outcrops of ultramafic rocks are known. Zircons with devonian metamorphic rims in rocks from the North Patagonian Massif have no counterpart in the low metamorphic grade Chilean rocks. These Paleozoic metasedimentary rocks were also intruded by Pennsylvanian and Jurassic granitoids. © 2018, Servicio Nacional de Geologia y Mineria. All rights reserved.
Notas
Indexación Scopus
Palabras clave
Fold and Thrust Belt, Argentina, Volcanology, Chaitenia, Devonian, Metamorphic complexes, North patagonian massif, U-Pb zircon ages
Citación
Andean Geology Volume 45, Issue 3, Pages 301 - 3171 September 2018
DOI
10.5027/andgeoV45n3-3117