Seminar

The effect of flat-slab subduction on magmatism and contractional orogenesis is a fundamental component of convergent-margin tectonics, yet the feedbacks among subduction angle, volcanism, and surface processes remain enigmatic. New geochronological and sedimentological constraints on Cenozoic magmatism and upper crustal exhumation in the southern central Andes of western Argentina (30.5°S) reveal Neogene changes in volcanism, foreland/hinterland depositional environments, sediment provenance, and accumulation rates as the retroarc region was structurally partitioned by various Andean ranges before and during slab flattening. Detrital zircon U-Pb age signatures from western (Calingasta hinterland basin), central (Talacasto wedge-top basin), and eastern (Bermejo foreland basin) retroarc segments of western Argentina record syndepositional volcanism and unroofing of multiple tectonic provinces. Patterns of Andean erosion and sedimentation record the initiation of shallow subduction and increased plate coupling, with eastward migration of magmatism, shortening, and foreland basin subsidence.