The Influence of Magma Storage and Ascent Conditions on Laguna del Maule Rhyolite Eruptions

Abstract The scarcity of historical rhyolite eruptions means that volcanological and petrological studies past are a key tool for assessing the potential future hazardous activity improving interpretations unrest signals. For last 18 ky, Laguna del Maule (LdM) volcanic complex in Chile has erupted primarily rhyolites but with differing magma compositions, eruption styles eruptive volumes. Rapid surface uplift episodic seismic at LdM over two decades emphasized need to understand both recent evolution magmatic system most likely scenarios. Using mineral composition, geothermobarometry MELTS modeling, we assess influence storage ascent conditions on magnitude three rhyolites. Magmas first largest Plinian-ignimbrite (LdM: rdm; >17 km3 DRE) form distinct assemblage An28–60 plagioclase, amphibole quartz derived from plumbing large pressure range (90–350 MPa). We suggest rdm was triggered by recharge overpressure within ~ 90 MPa chamber high-silica (>76.5 wt.% SiO2) rhyolitic melt. appears have reset conditions, such subsequent been smaller (<4 DRE), involved less evolved melt (<75.8 produced (sub)Plinian-effusive sequences. Of these, studied earliest (Los Espejos: rle) (Las Nieblas: rln). Both assemblages An20–34 plagioclase biotite formed water-saturated crystal-poor batches limited ranges (ΔP 50 MPa) rhyodacitic mush reservoir. rle rln were injection water-rich volatile exsolution; transition effusive behavior occurred because changes temperature (rle) or decompression rate (rln). Similarities high content inferred current low-density body petrologically determined source magmas fed subplinian-effusive next will be similar.