Thermochronological Studies of High-Grade Metamorphism: The Grenville Terrane

石榴石是一种常见的变质矿物， 高档的雪茄 这个项目将探索 U、Pb、Nd和Sm在石榴子石中充分不动，如果 可以观察到石榴石从核到边缘的年龄进程， 它可以等同于在活跃的逆冲变质作用期间的生长。 如果成功，石榴石生长年龄信息可以结合 用地质测温法追踪温度变化率 在变质作用期间。 该项目将评估阻塞 U、Pb、Nd和Sm在钙质岩中的扩散温度， 富铁石榴石，并将研究分区石榴石从两个井- 研究了高级变质作用的地区-格伦维尔 安大略、纽约和太古代皮克威托内域 马尼托巴。 结果，如果成功，将提供一种方法， 确定高温变质作用的加热速率， 在造山作用研究中具有重要意义的参数 但目前无法测量或令人满意地估计。

Garnet is a common metamorphic mineral in many medium and high-grade terranes. This project will explore the possibility that U, Pb, Nd and Sm are sufficiently immobile in garnet that if an age progression from core to rim of garnets can be observed, it may be equated to growth during active prograde metamorphism. If successful, garnet growth age information can be combined with geothermometry to follow the rate of temperature change during metamorphism. The project will evaluate the blocking temperatures for the diffusion of U, Pb, Nd and Sm in calcic and iron-rich garnets, and will examine zoned garnets from two well- studied areas of high grade metamorphism - the Grenville of Ontario and New York and the Archean Pikwitonei Domain of Manitoba. Results, if successful will provide a method to determine heating rates in high temperature metamorphism, a parameter that has considerable importance in orogenic studies but can not be measured or satisfactorily estimated at present.