Rates of Magma Ascent, Degassing and Crystallization - Controls on Eruptive Processes

9614753现金男它建议量化的影响，岩浆上升速率的挥发性损失和结晶，通过详细研究的几个喷发的产品，代表了一系列的喷发风格，规模和岩浆成分。中心重点将是重新审查1980年至1986年圣海伦斯火山的爆炸和喷发产物，具体目标是确定喷发率与火山碎屑结构之间的定量关系，并审查导致1980年从火山喷发转变为纯粹喷发的条件。 对其他火山喷发（即新西兰的陶波火山和意大利的维苏威火山）的沉积物进行进一步研究，将使这项工作能够推广到不同的岩浆成分和喷发条件。 随着这些研究的结果，它将有可能评估的重要性，分别与外部水的相互作用和成分的依赖性的结晶在生成的多孔和微晶火山碎屑的因素，如。 本次调查的更大目标将是确定物理过程，控制喷发风格的中高度硅质岩浆系统。

9614753 Cashman It is proposed to quantify the effect of magma ascent rate on both volatile loss and crystallization through a detailed study of the products of several eruptions representing a range of eruptive styles, magnitudes, and magma composition. The central focus will be to re-examine the 1980-1986 explosive and effusive products of Mount St. Helens, with the specific goals of determining quantitative relations between eruption rate and pyroclast textures, and examining the conditions that led to the 1980 transition from pulsatory explosions to purely effusive eruptions. Additional studies of deposits from other well characterized volcanic eruptions (i.e. Taupo in New Zealand, and Vesuvius in Italy) will permit generalizations of this work to different magma compositions and eruptive conditions. With the results of these studies, it will be possible to evaluate the importance, respectively, of factors such as interaction with external water and compositional dependence of crystallization in the generation of variably vesicular and micro-crystalline pyroclasts. The larger goal of this investigation will be to determine the physical processes that control eruptive styles in intermediate-to-highly siliceous magmatic systems.