Volatile Migration in Silicic Lavas

内生火山碎屑流可能毫无征兆地从推进的相对干燥的硅质熔岩的远端部分出现，这表明挥发物浓度较高。本项目将调查挥发物迁移的过程，并将涉及以下活动：1)模拟硅熔岩流的冷却过程，以量化结晶、角化和泡化过程；2)测定St. Helens、Santiaguito和St. Augustine活动英安岩穹丘中挥发物的分布、同位素特征和水泡结构；3)通过扫描电镜和变形实验表征硅质熔岩微裂缝的形态和能量学特征，评价微裂缝在挥发性输运中的可能作用。PI将从事野外采集，Novarupta圆顶测绘，实验研究和结果综合。

Endogenic pyroclastic flows may emerge without warning from distal portions of advancing, relatively dry silicic lava, suggesting concentration of volatiles. This project will be an investigation of processes by which volatiles migrate, and will involve the following activities: 1) Modeling of the cooling of a silicic lava flow to quantify processes of crystallization, brecciation and vesiculation; 2) measuring distribution and isotopic signatures of volatiles, and mapping vesicular textures in active dacite domes at St. Helens, Santiaguito, and St. Augustine; 3) characterizing the morphology and energetics of microcracis in silicic lavas through SEM and deformation experiments to evaluate the possible role in volatile transport. The PI will be engaged in field collecting, mapping on Novarupta dome, experimental studies, and synthesis of results.