Cerro Chascon-Runtu Jarita is a complex of lava domes located inside, but probably unrelated to, the Pastos Grandes caldera.
Located in the floor of the Pastos Grandes caldera, these domes were erupted after injection of mafic magmas in the deep less than 100,000 years ago.
Together with other lava domes like Cerro Chao this complex is part of the young surface expression of the APVC and may indicate the future location of a caldera.
[3] Geochemical analysis led de Silva (1994) to suggest that they may be the latest eruptive cycle of the APVC, either as part of a reactivation or waning of that system.
Their orientation in northwestward direction is consistent with the regional trends but may also be influenced by the Pastos Grandes caldera structure.
[3] Cerro Chascon is formed from a cicle of lava flow lobes[2] with a central plug with a diameter of 200 metres (660 ft).
[2] The lava dome has a volume of 5 cubic kilometres (1.2 cu mi)[1] with a maximum altitude of 5,190 metres (17,030 ft).
[3] Morro Chascoso and Pabelloncita Loma are cone shaped domes with blocky slopes with talus and central depressions.
[3] The lavas of this complex are of potassium-rich calc-alkaline origin, and are highly viscous with large difference between two magma types.