We present first P-T estimates of southern Argentine Precordillera collisional belt.
Metasedimentary and metabasaltic rocks reached conditions of 345–395 °C, 7.0–9.3 kbar.
Metamorphic gradient (13 °C/km) is comparable with subduction-related gradients.
Sedimentation was not contemporaneous with accretion as occur in accretionary prisms.
The development of a collision zone supports the existence of Chilenia.