Contrasting tectonic settings in Northern Chon Aike Igneous Province of Patagonia: subduction and mantle plume-related volcanism in the Marifil formation

Abstract

The northern zone of the Chon Aike Igneous Province, located in the North Patagonian Massif,exhibits extensive outcrops of Jurassic volcanic rocks of the Marifil Formation. In the Arroyo Verdearea, the initial volcanic stage of the Marifil Formation, that we denominate V0 (192.6 ± 2.5 Ma),includes coulées, megabreccias and lapilli tuffs assigned to plinian-type volcanism. This magmatismwas generated by cold-wet-oxidized magmas that resemble those produced in activecontinental margins and volcanic arcs. The second stage, located unconformably over the first,includes welded lava-like ignimbrites, massive lapilli tuff and rhyolitic lava flow that resemble theSnake River-type volcanism. The magma that produces this volcanic stage exhibit the characteristicsof hot-dry-reduced magmas emplaced in intraplate continental environments associatedwith continental rifting. This stage coincides with the V1 volcanic episode early recorded in theMarifil Formation.