SHORT ERUPTION WINDOWS FOR LARGE VOLUME DOMES IN THE ALTIPLANO PUNA VOLCANIC COMPLEX, CHILE

Volcanism in the waning stages of the Altiplano Puna Volcanic Complex (APVC) of the Central Andes transitioned from large volume ignimbrite eruptions to smaller domes and coulees. Five of these Quaternary silicic domes: the Chao, Tocopuri, Chillahuita, Chascon, and Chanka lava domes, erupted approximately 40 km³ of dacite and rhyodacite over an area of 2000 km². Eruption ages and zircon crystallization ages of these domes are within analytical error, which is more consistent with the modern arc front composite volcanoes, but geochemically, the domes are more resemble the ignimbrites. This creates an inconsistency in the magmatic evolution of the APVC and the relationship between the arc volcanoes and the ignimbrites. Here we present hornblende major and trace element data from three domes: Chillahuita, Tocopuri and Chao and compare lavas from three major volcanic centers which are adjacent to the domes, Volcàn Ollagüe, Linzor volcano, and Volcàn San Pedro. We compare these data to existing hornblende and zircon trace element data for the lavas and local ignimbrites to determine the relationship of the domes to both the ignimbrites and the arc front composite volcanoes. We test the hypothesis that the domes are sourced from a similar source to the ignimbrites but were remobilized quickly from a near solidus mush.