The country rocks of Devonian magmatism in the North Patagonian Massif and Chaitenia

ABSTRACT 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...

Descripción completa

Guardado en:
Detalles Bibliográficos
Autores principales: Hervé,Francisco, Calderón,Mauricio, Fanning,C. Mark, Pankhurst,Robert J., Rapela,Carlos W., Quezada,Paulo
Lenguaje:English
Publicado: Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2018
Materias:
Acceso en línea:http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062018000300301
Etiquetas: Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
Descripción
Sumario:ABSTRACT 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.