CAREER: Exhumation of a High-Grade Metamorphic Terrane, and Late-Stage Orogenic Collapse in the Southeastern New England Appalachians

阿巴拉契亚山脉是由在阿巴拉契亚造山活动期间碰撞的各种微大陆、海洋和大陆火山弧和（元）沉积域组成的复合山带。阿巴拉契亚地区的地质调查通常强调各种地体的合并史。本研究的重点是深层域的同步到碰撞后的挖掘历史，以及山带的晚期崩塌，以获得对阿巴拉契亚北部及其他地区晚到后山脉形成过程的基本认识。研究是在阿巴拉契亚山脉的新英格兰东南部地区通过一个强有力的综合研究和教育计划进行的。新英格兰东南部的阿巴拉契亚山脉通常由三个地形组成。从西到东分别是梅里马克、纳肖巴和阿瓦隆。纳肖巴地体被中等北西倾断裂所包围。根据褶皱几何形状、变质特征以及Nashoba地体约3.95亿年前的融化与构造上覆Merrimack地体约3.95亿年前的侵入之间的明显关系，初步的野外数据表明，Nashoba地体内部较深的域可能向东挤压。此外，初步的野外观测表明，大多数地间和地内剪切带显示出晚期低等级正常运动的证据，可能与晚期山体崩塌有关。本研究的目的是通过野外测绘、详细的结构分析和尖端的放射性测年技术相结合，研究高温和低温挖掘和塌陷机制。将研究和实地工作整合到本科生的经历中是这个项目的核心。来自波士顿地区各个地球科学部门的学生被鼓励参与和合作地质实地研究课程，为他们提供了与同龄人讨论研究并创建更强大社区的绝佳机会。本科和硕士学生随后的论文研究涉及波士顿学院、麻省理工学院和马萨诸塞大学阿默斯特分校的分析工作，加强了三个实验室之间以及学生和教师之间的关系。学生，特别是女性和少数民族学生，被鼓励参加现有的课程，部门咨询活动和其他地球科学部门。来自弱势群体的学生可以通过波士顿学院AHANA（非裔美国人、西班牙裔、亚裔和美洲原住民）学生办公室和针对低收入和第一代大学生和/或弱势群体的本科生的麦克奈尔项目获得。本项目资金由美国国家科学基金EAR构造学项目提供，并得到美国国家科学基金EAR地球镜和教育与人力资源项目的支持。

The Appalachians are a composite mountain belt consisting of various microcontinents, oceanic and continental volcanic arcs and (meta)sedimentary domains that collided during the Appalachian mountain building events. Geological investigations in the Appalachian commonly emphasize the amalgamation history of the various terranes. This proposal focuses on the syn- to post-collisional exhumation history of the deeper domains, as well as late-stage collapse of the mountain belt, to gain fundamental insights into late- to post-mountain formation processes in the northern Appalachians and beyond. Research is carried out in the southeastern New England section of the Appalachians through a strongly integrated research and educational plan.The southeastern New England Appalachians generally consist of three terranes. From west to east they are the Merrimack, Nashoba and Avalon terranes. The Nashoba terrane is bounded by moderately NW-dipping faults. Preliminary field data suggest that deeper domains within the Nashoba terrane may have extruded towards the east, based on fold geometries, metamorphic characteristics and the apparent relationship between approximately 395 million year melts in the Nashoba terrane and approximately 395 million year intrusions in the structurally overlying Merrimack terrane. Furthermore, preliminary field observations indicate that most inter- and intra-terrane shear zones show evidence for late low-grade normal movement, presumably related to late-stage mountain collapse. The purpose of this research is to investigate both the high-temperature and low-temperature exhumation and collapse mechanisms through a combination of field mapping, detailed structural analysis and cutting-edge radiometric dating techniques.Integration of research and field work into the undergraduate student experience is central to this project. Students from various geoscience departments in the Boston area are encouraged to participate and collaborate through a Geological Field Research course, giving them an excellent opportunity to discuss research with their peers and creating a stronger community. Subsequent thesis research by undergraduate and MS students involves analytical work at Boston College, MIT and UMass Amherst, strengthening the relationship between the three labs and between students and faculty. Students, especially women and minority students, are encouraged to participate through existing courses, departmental advising activities and other geoscience departments. Students from underrepresented groups are reached through the Boston College AHANA (African-American, Hispanic, Asian and Native American) student office and the McNair program for undergraduates who are low-income and first-generation college participants, and/or part of underrepresented groups. Funding for this project is provided by the NSF EAR Tectonics Program, with support from the NSF EAR EarthScope and Education and Human Resources Program.