Reaction Kinetics and Geospeedometry

火成岩和变质岩石学的基本目的之一是利用观察到的矿物组合和成分来推断岩石的热历史。这一持续的奖励将支持反应动力学和地速测量学的研究，重点是利用均相反应（即单相反应）的动力学来推断热历史。重点将放在火山玻璃中的水化物相互转化反应（H2Om+O= 2OH）上，不仅因为它在地质测速学中的重要性，而且因为H2O是地球上最丰富的挥发性成分，在火山爆发和熔体的物理和化学性质中起着关键作用。先前的研究提供了一个地质速度计，并允许通过红外分析确定含水火山玻璃的冷却速率。在之前的工作中遇到的一些意想不到的问题（例如，需要一个新的校准）已经部分解决。有了这个持续的奖励：(1)红外技术将被校准到高总H2O含量-校准是提议的工作和其他关于含水系统的工作的基础；(2)在高温高压下对反应的形态和动力学进行原位实验研究；(3)确定天然和实验含水玻璃的冷却速率分布。

9706107 Zhang One of the basic aims of igneous and metamorphic petrology is to infer the thermal history of rocks using observed mineral assemblages and compositions. This continuing award will support research in reaction kinetics and geospeedometry, concentrating on using kinetics of homogeneous reactions (i.e., reactions in a single phase) to infer thermal history. The focus will be on the reaction of hydrous species interconversion (H2Om+O= 2OH) in volcanic glasses, not only because of its importance in geospeedometry, but also because H2O is the most abundant volatile component in the earth and plays the critical role in explosive volcanic eruptions and in physical and chemical properties of melts. Previous research provided a geospeedometer and allows the determination of the cooling rate of hydrous volcanic glasses through IR analyses. Some of the unexpected problems encountered this previous work (e.g., the need for a new calibration) have been partially addressed. With this continuing award: (1) the IR technique will be calibrated to high total H2O content - the calibration is basic to the proposed work and that of others on hydrous systems; (2) in situ experimental studies at high temperature and pressure on speciation and kinetics of the reaction will be carried out; and (3) cooling rate profiles in natural and experimental hydrous glasses will be determined.