Geochemical and geochronological data on the provenance of the Devonian Cabanillas Group in the Western and Coastal Cordilleras of Southern Peru

Abstract

We present a combined sedimentological and geochemical data-set including U-Pb LA-ICP-MS age data of detrital zircons. The aim of our study is to further constrain the plate tectonic setting of the Western Gondwana margin during Devonian time and particularily the development of the sedimentary basin, where the Cabanillas Group was deposited. From the framework mineral analysis and the geochemical composition of tourmalines and rutile we conclude that the major part of the detritus is well recycled and underwent at least one resedimentation event before final deposition. A minor part of the detritus from the Coastal deposits is inmature and could reflect synsedimentary magmatism. U-Pb ages reveal that detrital zircons related to the Farnatinian and to the Brazilian events are ominipresent in the Western Cordillera and Coastal successions. The zircons related to the Farnatinan event derived from a western source on the Arequipa Massif. As intrusive rocks related to the Brazilian event are not known from the Arequipa Massif; the respective zircons must have been derived from eastern sources on the Amazonia craton. Both successions were derived in large parts from a cornmon source area on the Amazonia craton, with the Coastal succession containing additional input from the Arequipa Massif which the Western Cordillera deposits lack.