Geology, petrology and geochemistry of the dome complex of Huequi volcano, southern Chile

huequi, a little-known volcano in the southern part of the andean southern volcanic zone (ssvz), shows a regionally unusual eruption style, mineralogy and geochemistry. the volcano comprises multiple highly-eroded lava domes. past eruptions were accompanied by relatively minor explosive activity, most recently from 1890-1920. the rocks erupted by huequi range from basaltic andesite to dacite, and are highly distinctive when compared to other volcanoes of the ssvz, being k-poor and al-rich, and containing euhedral hornblende phenocrysts. overall compositions suggest a notably water-rich magma source, evolving through high levels of fractionation and subsequent degassing to produce highly porphyritic dome-forming andesites. the ultimate causes of water-rich magmas at this point in the arc remain unclear.