Upper Pliocene to Lower Pleistocene volcanic complexes and Upper Neogene deformation in the south-central Andes (36°30′-38°S)

Abstract

The Agrio (37º51´S-70º26´W), Vilú Mallín (37º28´S-70º45´W), Trohunco (37º18´S-71º01´W), Domuyo (36º38´S-70º26´W) and Los Cardos-Centinela (37º06´S-70º52´W) volcanic complexes in Argentina are the principal Upper Pliocene to Lower Pleistocene volcanic complexes that occur in the Main Andean Cordillera east of the modern volcanic front in Chile, in the Southern Volcanic zone.Volcanic rocks from these centers along with their stratigraphic relations with nearby Neogene volcanic units provide constraints on the age and style of Neogene deformation in the modern backarc of the Southern Volcanic Zone between 36°30´ and 38°S. New and published radiometric ages and stratigraphic and structural relations show that the region was affected by a latest Miocene compressional deformation that took place between 9 and 6.8 Ma.A heterogeneous picture emerges for the younger deformation of the region which lies along the Quaternary orogenic front.The most important structures include a NNW-trending fault system that joins the Trohunco and Los Cardos-Centinela complexes and is characterized by compressive deformation, and a NE-trending extensional fault system along which the Agrio caldera, Vilú Mallín and Domuyo volcanic complexes are aligned. Overall, the backarc in this region was affected by compressional deformation in the late Miocene and subjected to tectonic collapse and transpressional deformation during the late Pliocene to Quaternary.