Establishing Genetic Relationships between the Takidani Pluton and Two Large Silicic Eruptions in the Northern Japan Alps

Abstract The Takidani pluton (1·1–1·6 Ma) represents a shallow magmatic reservoir at the base of an exhumed caldera floor. deposits two large caldera-forming eruptions, Nyukawa Pyroclastic Flow Deposit (1·76 Ma; crystal-rich dacite) and Chayano Tuff Ebisutoge Deposits (1·75 sequence crystal-poor rhyolite), are distributed concentrically around pluton. We use major trace element chemistry whole-rock, glass minerals to show that (1) dacite (>400 km3 DRE; dense rock equivalent) is erupted portion mush zone constituting (2) rhyolite (>100 DRE) was extracted from deeper part this vertically extended plumbing system. Whole-rock geochemistry indicates compositions were produced dominantly through crystal fractionation amphibole, pyroxene plagioclase in mid lower crust subsequently emplaced upper prior eruption solidification, respectively. Chayano–Ebisutoge compositionally distinct magmas its generation associated with substantial contribution crustal melts. However, orthopyroxene textures provide strong evidence ascending percolated Takidani–Nyukawa eruption. Overgrowth ‘rhyolitic plagioclase’ on ‘xenocrystic dacitic typical extraction accumulation rhyolitic melts could have occurred less than 10 kyr (i.e. time between eruptions) eruption, providing maximum timescales for pre-eruption storage. Overall, our findings progressive growth thermal maturation system over hundreds thousands years imply volcanic eruptions can occur relatively short succession without dramatic changes system, thus complicating identification signs impending