The magmas that formed Parinacota and Pomerape are considered to be a group distinct from these that formed older volcanic centres in the region, but also distinct from the magmas that formed the subsidiary vent of Pomerape and the Ajata cones; these tend to be more mafic. In turn, the younger and older Ajata cone lavas have different compositions, one having a high quantity of strontium and the other a low one.