Collaborative Research: Investigation of Volatile Gradients in Silicic Magma Chambers

来自化学分区岩浆房的物质的两个例子 是加州的主教凝灰岩和下班德利尔 新墨西哥州的凝灰岩。在主教凝灰岩中， 推翻了岩浆库的内容物 保存了一个地层记录的化学成分， 室。 下班德利尔凝灰岩的喷发 保留了化学分层， 在房间里出现了。 两者的区别 喷发表明主教凝灰岩室的密度 （挥发性）梯度，而下Bandelier岩浆房 相对于挥发物来说更均匀。 这个项目 将量化两个腔室中的挥发物含量， 分析斑晶中捕获的熔融包裹体， 代表不同的地层层位。 离子和电子 将使用微探针技术来确定含量 熔体包裹体中H、F、Cl和S的含量随 原始岩浆房的深度，从而确定 挥发性梯度的大小。 电子探针分析 将有助于确定 熔融包裹体和离子探针显微分析的选择 亲石微量元素有助于确定 每个斑晶的地层位置。 私人侦探会做离子探针的工作。 他正在与 新墨西哥州矿业研究所的P.凯尔博士说， 技术，谁来做剩下的。 ***

Two examples of material from chemically zoned magma chambers are the Bishop Tuff in California and the Lower Bandelier Tuff in New Mexico. In the Bishop Tuff, the eruption appears to have overturned the contents of the magma chamber, preserving a stratigraphic record of the chemistry of the chamber. The eruption of the Lower Bandelier Tuff did not preserve the chemical layering which has been deduced to have been present in the chamber. The difference between the two eruptions suggests that the Bishop Tuff chamber had a density (volatile) gradient while the Lower Bandelier magma chamber was more homogenous with respect to volatiles. This project will quantify the volatile content in the two chambers by analyzing trapped melt inclusions in phenocrysts which represent different stratigraphic horizons. Ion and electron microprobe techniques will be used to determine the content of H, F, Cl and S in the melt inclusions as a fuction of depth in the original magma chamber, thereby determining the magnitude of the volatile gradient. Electron probe analyses for major elements will help determine the unaltered nature of melt inclusions and ion probe microanalyses of selected lithophile trace elements will help determine the original stratigraphic position of each phenocryst. The PI will do the ion microprobe work. He is collaborating with Dr. P. Kyle of of the New Mexico Institute of Mining and Technology, who will do the rest. ***