Petrological character of the juvenile materials Whole-rock composition of the juvenile ejecta of the 2000 eruption
During the 2000 eruption, erupted magma changed from phenocryst-poor andesitic magma to plagioclase-phyric basaltic one. Submarine eruption before the caldera collapse and summit eruption in the early stage of the caldera collapse produced andesitic juvenile materials with 54 wt.% of whole-rock SiO2 content and the serise of eruption in August issued basaltic juveniles with 51.5 wt.% of whole-rock SiO2 content. Owing to high-concentration of plagioclase crystals with high-An content, the basaltic juveniles of August eruptions show high (ca 18wt.%) of whole-rock Al2O3 content.
