La Pacana has erupted two ignimbrites which differ in composition and were emplaced one shortly after the other: The dacitic Atana ignimbrite and the rhyolitic Toconao ignimbrite. The Atana ignimbrite was once considered part of the Guaitiquina ignimbrite, which was later split off, while the Puripicar ignimbrite may be correlated with the Atana instead. Also, some of the ignimbrites erupted by La Pacana originally were attributed to Cerro Guacha. Both ignimbrites originated from different parts of the same magma chamber and their origin in the La Pacana caldera is established by isotope ratios of the rocks and the geographical distribution of their outcrops.