Experimental Study of Water Leakage from Melt Inclusions in Quartz During Laboratory Heating

被困在火成岩矿物中的玻璃状硅酸盐熔体包裹体包含了活火山岩浆室中存在的熔体样本。这些包裹体提供了测定岩浆中水浓度的最佳工具之一，并已被用于测定岩浆中存在的挥发物。此外，由于水在硅酸盐熔体中的溶解度作为P、T和X的函数是众所周知的，因此可以从水的含量来估计捕获压力。用熔体包裹体来理解岩浆库中的过程所需要的一个基本假设是，包裹体在捕获后没有丢失或获得成分。虽然这一假设通常对大多数熔体成分是有效的，但众所周知，水（或氢）很容易在大多数矿物中扩散，并且可以在夹带后从包裹体中损失（或通过包裹体获得）。该项目包括使用天然和合成硅酸盐熔体包裹体进行系统研究，以确定最有可能保留熔体包裹体原始含水量的实验室加热技术。天然和合成硅酸盐熔体包裹体将在加热前进行表征，以确定尺寸、形状以及与晶体表面或断裂的距离，然后通过几种技术中的一种进行加热，随后对熔体进行拉曼分析以确定水的含量。这些结果将用于制定选择和均质化结晶硅酸盐熔体包裹体的方案，以最大限度地减少水分损失。这个项目更广泛的影响包括对研究生和本科生进行现代实验和分析技术的培训。这个项目的一个重要组成部分是建立罗德数字图书馆。该图书馆将包括罗德博士在其68年的职业生涯中发表的所有流体内含物的数字图像。这些图像将通过万维网提供给教育和研究使用，并成为在广泛的地球科学领域进行教学和研究的重要资源。

Glassy, silicate melt inclusions trapped in igneous minerals contain samples of the melt that was present in the magma chamber beneath an active volcano. These inclusions provide one of the best tools available for determining water concentrations in magmas, and have been used to determine the volatiles present in magmas. Moreover, because the solubility of water in silicate melts as a function of P, T and X is well known, the pressure at trapping may be estimated from the water content. A basic assumption required to use melt inclusions to understand processes in magma chambers is that the inclusions have not lost or gained components following trapping. While this assumption is generally valid for most melt components, it is known that water (or hydrogen) diffuses through most minerals very easily and can be lost from (or gained by) inclusions following entrapment.This project involves a systematic study using both natural and synthetic silicate melt inclusions to identify those laboratory heating techniques that are most likely to preserve the original water content of the melt inclusions. Natural and synthetic silicate melt inclusions will be characterized before heating to determine the size, shape, and distance from the crystal surface or fracture, and then heated by one of several techniques, followed by Raman analysis of the melt to determine the water content. These results will be used to develop a protocol for selecting and homogenizing crystallized silicate melt inclusions that will minimize water loss.Broader impacts of this project include the training of both graduate and undergraduate students in modern experimental and analytical techniques. An important outreach component of this project involves the establishment of the Roedder Digital Library. The library will include digital images of all the fluid inclusions that Dr. Roedder has published over his 68-year professional career. These images will be made available for educational and research usage through the worldwide web and become an important resource for those teaching and conducting research in a broad range of earth science areas.