Distribution and Origin of Gas and Volatiles in Bishop Rhyolitic Magma

这是为了继续一项确定大量流纹岩岩浆-毕晓普凝灰岩中天然气喷发前分布的项目。首先，PI对熔体包裹体、浮石形成压力和气孔性的研究结果表明，在喷发前的毕晓普岩浆中存在着令人惊讶的大量过剩气体。为了确定毕晓普岩浆中的天然气含量，PIS计划对选定的一组新旧地层控制地点的浮石碎屑进行全面研究。他们将测定单个浮石碎屑的囊泡和晶体含量，以及斑晶的组成，以及石英和长石斑晶中封闭和沙漏熔体包裹体中H2O、CO2、Cl、BA、U、Rb和其他元素的浓度。这项工作将首次确定喷发前岩浆体中气体的分布。然后，这些数据将被用来检验关于岩浆体中气体聚集的理论及其对火山喷发性质的影响。

This is for continuation of a project to determine the preeruptive distribution of gas in a large body of rhyolitic magma, the Bishop Tuff. First results of the PI's studies of melt inclusions and of pumice formation pressure and vesicularity suggest that a surprisingly large excess of gas was present in preerupted Bishop magma. To definitely establish the amount of gas in the Bishop magma the PIs plan comprehensive studies of individual pumice clasts from a selected set of old and new stratigraphically controlled sites. They will determine the vesicle and crystal content of individual clasts of pumice as well as the compositions of phenocrysts and the concentrations of H2O, CO2, Cl, Ba, U, Rb and other elements in both enclosed and hourglass melt inclusions in quartz and feldspar phenocrysts. The work will result in the first determination of the distribution of gas in a preeruptive body of magma. This data will then be used to test theories on gas accumulation in magma bodies and its effect on the nature of volcanic eruptions.