Quartz‐Hosted Melt Inclusions as Windows Into Magma Assembly and Storage Processes in the Youngest Toba Tuff

Quartz-hosted melt inclusions are windows into the assembly and storage of compositionally zoned magmas systems like giant magma body responsible for 2,800 km3 Youngest Toba Tuff (YTT), Indonesia. Feldspar-sensitive element concentrations interelement ratios in YTT quartz-hosted found to cluster three discrete inclusion populations. Each population represents a small fraction overall range compositions no more than ∼12% ∼21% fractional crystallization at mostly eutectoid conditions accounts trace elements variations within them. Kinships between host matrix glasses co-hosted phases interpreted as evidence spatially chemical domains broadly system. Quartz growth dominant portion system apparently occurred after extraction from mush, whereas chemically distinct crystal cores crystal-rich, low-silica may have been derived mush during or remobilized by rejuvenation. Collectively, zoning appears developed prior most quartz growth, likely “bottom-up” due mush-derived heterogeneity.