COLLABORATIVE RESEARCH: Thermal Evolution of the Maryland Pennsylvania Piedmont: Application of U-Pb Geochronology to Collisional Tectonics

碰撞过程中地壳边缘的热演化是构造学中的一个重要问题，因为通过逆冲叠加和伴随的岩浆作用对地壳进行的热和物理改造对大陆的生长起着重要的作用。该项目将专注于马里兰州、特拉华州和宾夕法尼亚州的山前地区，那里发育了大陆边缘，随后与边缘相撞，并伴随着逆冲堆积和低压高温变质作用而导致的增厚。这项工作将通过记录超厚事件和伴生岩浆作用的岩石中锆石和独居石的高精度U-Pb年龄来建立碰撞造山带的构造年代学。从弧期到逆冲堆积到部分熔融的整个造山旋回的持续时间可以在研究区唯一确定，并应为碰撞环境中变质-火成-构造作用的速率提供基准评估。

The thermal evolution of crust margins involved in collisional processes is an important issue in tectonics, as the thermal and physical modification of the crust through thrust stacking and associated magmatism play an important role in the growth of continents. This project will focus on the piedmont of Maryland, Delaware and Pennsylvania where a continental margin arc developed and subsequently collided with the margin with attendant overthickening by thrust stacking and low pressure, high temperature metamorphism. The work will develop the tectonic chronology of the collisional orogen through high precision U-Pb ages of zircons and monazite from rocks that record the overthickening event and associated magmatism. The duration of the entire orogenic cycle from arc stage through thrust stacking to partial melting can be uniquely determined in the study area, and should provide a benchmark assessment of rates of metamorphic-igneous-tectonic processes in a collisional environment.