Mixing processes involving hotter or more mafic magmas played a role in the genesis of Uturuncu rocks, as did fractional crystallization processes and contamination with crustal rocks. The origin of these magmas appears to relate to the Altiplano-Puna magmatic body, which generates melts through differentiation of basaltic magmas first to andesites and then to dacites before being transferred to the shallow crust below Uturuncu from where it was then erupted through buoyancy-dependent processes. Magma composition has been stable over the history of the volcano.