DOI: http://dx.doi.org/10.5027/andgeoV44n1-a01

Ultramafic rocks in the North Patagonian Andes: is their emplacement associated with the Neogene tectonics of the Liquiñe–Ofqui Fault Zone?

Francisco Hervé, Francisco José Fuentes, Mauricio Calderón, Mark Fanning, Paulo Quezada, Robert Pankhurst, Carlos Rapela

Abstract


Serpentinites and fresh or partially serpentinized harzburgite crop out in the western slope of the North Patagonian Andes of continental Chiloé (41°44’-42°12’S). These rocks are spatially associated with low-grade metamorphic rocks containing Cenozoic detrital zircons. The metamorphic rocks, together with Devonian metasediments, have been mapped previously as Late Paleozoic-Triassic metamorfic complex, an age no longer tenable for at least part of the complex. Transpressional tectonic emplacement of the ultramafic body or bodies is thought to have been related to activity on the Liquiñe-Ofqui Fault Zone, following a late Oligocene-Early Miocene extensional phase in the forearc region of the present Andes. This fault zone occurs immediately east of the outcrops of the ultramafic rocks and has been interpreted previously as generating a hemi-flower or flower structure.

Keywords


Serpentinites; North Patagonian Andes; Liquiñe-Ofqui Fault Zone; Neogene tectonics

How to cite this article Hervé, F., Fuentes, F., Calderón, M., Fanning, M., Quezada, P., Pankhurst, R., and Rapela, C., 2017, Ultramafic rocks in the North Patagonian Andes: is their emplacement associated with the Neogene tectonics of the Liquiñe–Ofqui Fault Zone?: Andean Geology, v. 44, no. 1, p. 1-16., doi:http://dx.doi.org/10.5027/andgeoV44n1-a01