Monazite as a Thermochronometer for Prograde Metamorphism

9316166 Harrison这个项目提出的实验将有助于更好地理解独居石作为温度计。选择独居石作为研究对象，是因为其对Pb*的保留性质及其在成岩过程中不寻常的（作为一种辅助矿物）行为表明，它可以作为一种系统，在泥石的渐进变质过程中连续记录热年代学信息。为了利用这一观察结果，需要进行三个不同但最终相互关联的研究：对独居石进行U-Th-Pb微量分析的发展，泥质组合中LREE氧化物的稳定性和反应动力学，以及Pb在独居石中的扩散。这些研究将导致利用Th-Pb系统确定造山带加热阶段的离散反应事件，以及对独居岩中Pb闭合温度的精确了解。

9316166 Harrison This project proposes experiments that will lead to a better understanding of monazite as a thermochronometer. Monazite was selected for study because its retentive nature for Pb* and its unusual (for an accessory mineral) behavior during diagenesis suggests its use as a system capable of continuously recording thermochronological information during prograde metamorphism of a pelite. Three distinct, but ultimately interconnected, studies are required to exploit this observation: development of U-Th-Pb microanalysis for monazite, the stability and reaction kinetics of LREE oxides in pelitic assemblages, and Pb diffusion in monazite. These studies will lead to utilization of the Th-Pb system to date discrete reaction events in the heating phase of orogenic terranes as well as a refined knowledge of the closure temperature for Pb in monazie.