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

Hervé, Francisco; Calderón, Mauricio; Fanning, Mark; Pankhurst, Robert; Rapela, Carlos W.; Quezada, Paulo. 2018 The country rocks of Devonian magmatism in the North Patagonian Massif and Chaitenia. Andean Geology, 45 (3). 301-317. https://doi.org/10.5027/andgeoV45n3-3117

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Official URL: http://dx.doi.org/10.5027/andgeoV45n3-3117

Abstract/Summary

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 “Grenvilleage” 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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.5027/andgeoV45n3-3117
ISSN:	0718-7092
Date made live:	07 Jan 2019 11:20 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/521966

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.5027/andgeoV45n3-3117

ISSN:

0718-7092

Date made live:

07 Jan 2019 11:20 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/521966