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，通过逆冲叠加和伴生岩浆活动对地壳进行热物理改造对大陆的发育起着重要作用。该项目将重点关注马里兰州、特拉华州和宾夕法尼亚州的山前地区，在那里大陆边缘弧发育，随后与边缘碰撞，并伴随推力堆积和低压、高温变质作用而过度增厚。这项工作将通过高精度的锆石和独居石U-Pb年龄来发展碰撞造山带的构造年代学，这些锆石和独居石记录了过增厚事件和相关的岩浆活动。研究区从弧期到逆冲叠加到部分熔融的整个造山旋回的持续时间可以独特地确定，并可为碰撞环境下变质-火成岩-构造过程的速率提供基准评价。

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.