Persistent gas emission originating from a deep basaltic magma reservoir of an active volcano: the case of Aso volcano, Japan

Volcanic gas emission is considered to reflect the degassing of magma beneath volcanoes. The combined observations measurement and petrological study are expected constrain volatile concentrations storage depths pre-eruptive primitive magma. Aso volcano (Japan) a constantly-monitored, persistently-degassing volcano, an ideal site acquire petrologic data. We analyzed melt inclusions phenocryst minerals Holocene basaltic eruption products, reported their major element concentrations. samples showed abundant evidence mixing, such as reverse mineral zoning, highly variable glass compositions. SiO2 measured in varied from 46.0–65.8 wt. %. High-volatile concentration, S up 3750 ppm, was only found mafic hosted by high-Fo olivine phenocrysts (~ Fo82). were determined concentrations: 2 4 km depth for Strombolian sub-Plinian eruption, respectively. volatile-rich magma, one end member mixed-magma, originated deeper level (> 10 km) than these reservoirs. Initial using multiple constraints: > 4.68 % H2O, 400—750 ppm CO2, S, 716 Cl, 324 F. observed variation volcanic composition best explained mixing segregated at least km, with that shallow This illustrated method identify responsible deep flux mature complex magmatic processes.