Payún Matrú is part of the backarc volcanic province, east of the Andes and east of the Peru-Chile Trench. The volcanic activity still relates to the subduction of the Nazca Plate beneath the South America Plate, however; one proposed mechanism is that a Miocene change in the subduction regimen led to the development of extensional tectonics and of faults that form the pathways for magma ascent, while other mechanisms envisage changes in mantle characteristics.