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

中文翻译：

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石英承载的熔体夹杂物作为窗口进入最年轻的鸟羽凝灰岩的岩浆组装和储存过程

石英承载的熔体包裹体是进入成分分区岩浆系统组装和储存的窗口，例如负责 2,800 公里³的巨大岩浆体印度尼西亚最年轻的鸟羽凝灰岩 (YTT)。发现 YTT 石英熔体包裹体中的长石敏感元素浓度和元素间比率聚集成三个离散的熔体包裹体群。每个群体代表 YTT 熔体组成整体范围的一小部分，并且在大多数共析条件下不超过 12% 到 21% 的部分结晶占其中的微量元素变化。宿主基质玻璃和共宿主相之间的亲缘关系被解释为岩浆在更广泛分区的岩浆系统中空间离散化学域的证据。系统主要部分的石英生长显然发生在从糊状物中提取熔体之后，而在更富含晶体、低硅质岩浆可能来自提取过程中的糊状物或通过糊状物再生而重新流动。总的来说，YTT 的化学分带似乎在大多数石英生长之前就已经形成，可能是“自下而上”的，这是由于糊状物衍生的熔体非均质性。