Collaborative Research: Provenance and Thermal Evolution of the Chugach-Prince William Terrane Flysch, Southern Alaska

楚加赫-威廉王子地体是在白垩纪至始新世大洋岩石圈俯冲(俯冲)过程中，沿北美西缘形成的广泛的增生杂岩。它是由接近海沟的火成岩侵入的，推测与洋脊(形成新的洋壳的地方)的俯冲有关，但该地体在海脊相互作用时的位置仍存在相当大的争议。关于其形成时的位置，有两种流行的假说：1)楚加赫-威廉王子地体或多或少形成在原地，山脊相互作用与现在俯冲的复活板块有关；或2)楚加赫-威廉王子地体形成于遥远的南部，在北纬48-49°附近被近海沟的火成岩侵入，随后通过类似于加利福尼亚州圣安德烈亚斯断层的走滑断层沿大陆边缘转移到阿拉斯加。楚加赫-威廉王子地体可能在遥远的南方形成，随后沿着大陆边缘平移，这是北美西部构造中的一个决定性事件，并对这些岩石的起源和热演化做出了可验证的预测。我们利用地质年代学、地层学、岩石学、构造地质学和地球物理学来揭示这种增生杂岩的源区和随后的热史。总而言之，这些数据对楚加赫-威廉王子地体的沉积和平移史产生了重要的限制，并对侧翼盆地的历史产生了影响，例如富含碳氢化合物的库克湾盆地。这项研究直接解决了北美构造中与地体形成、平移、吸积和盆地形成有关的几个关键问题，并有助于发展用于追踪沉积岩起源和热演化的地质年代学方法。这项工作的结果为了解盆地形成的时间和性质(包括富含碳氢化合物的地层)以及与侵入岩有关的贵金属矿床(金)的时间和范围提供了更好的构造框架。该项目也有一个强大的教育部分，旨在增加地球科学领域的学生数量，并最终增加劳动力，我们的努力部分集中在招收在地球科学领域任职人数不足的学生。我们通过凯克地质联盟参与对本科生的直接培训、指导和评估。通过该联盟的现有框架对学生进行招募和评估，这一努力包括让30%的非凯克学校的学生参与。有一个坚定的承诺，增加在地球科学管道中代表不足的学生的数量(这一群体包括非裔美国人、西班牙裔美国人和美洲原住民)，凯克地质联盟的新的多样性倡议保证了这一群体的更多参与。Keck联盟正在通过包括内部招聘和外部合作伙伴在内的几项战略，大幅增加代表人数不足的学生的参与人数。凯克地质联盟在有前途的学生的研究培训中发挥着主导作用，这些学生中的大多数都在攻读地球科学的硕士和/或博士学位。因此，该联盟为地球科学管道提供了聪明、有才华、训练有素的学生，其中许多人成为该领域的领导者。众所周知，积极从事研究的教师提供了一个成功和富有成效的学习环境，本科生水平的学生研究为学生提供了进入研究生院的动机、能力和准备，这些通常会导致在地球科学领域取得富有成效的职业生涯。

The Chugach-Prince William terrane is an extensive accretionary complex that formed along the western margin of North America during subduction (under-thrusting) of oceanic lithosphere in the Cretaceous to Eocene. It was intruded by near-trench igneous rocks inferred to be related to the subduction of an oceanic ridge (where new ocean crust is formed), but the location of this terrane at the time of ridge interaction is under considerable debate. There are two prevailing hypotheses for its position at the time of formation: 1) The Chugach-Prince William terrane formed more or less in place and ridge interaction was related to the now-subducted Resurrection plate; or 2) the Chugach-Prince William terrane formed far to the south, was intruded by near-trench igneous rocks near a latitude of 48-49°N, and was subsequently translated along the continental margin to Alaska by strike slip faults similar to the San Andreas fault in California. The possible formation of the Chugach-Prince William terrane far to the south and subsequent translation along the continental margin is a defining event in western North American tectonics and makes testable predictions for the origin and thermal evolution of these rocks. We use geochronology, stratigraphy, petrology, structural geology, and geophysics to unravel the source region of this accretionary complex and subsequent thermal history. Together, these data are yielding important constraints on the accretion and translation history of the Chugach-Prince William terrane and has implications for the history of flanking basins such as the hydrocarbon-rich Cook Inlet basin.This research directly addresses several key problems in North American tectonics related to terrane formation, translation, accretion, and basin formation, and is helping advance geochronologic methods used for tracking the origin and thermal evolution of sedimentary rocks. The results from this work are providing a better tectonic framework for understanding the timing and nature of basin formation (including hydrocarbon-rich strata), and the timing and extent of precious metals deposits (gold) associated with intrusive rocks. This project also has a strong educational component aimed at increasing the number of students in the geoscience pipeline and ultimately the workforce, and our effort is partly focused on recruiting students under-represented in the Geosciences. We are involved in the direct training, mentoring, and assessment of undergraduate students through the Keck Geology Consortium. Students are recruited, and assessed through the existing framework of the Consortium and this effort includes involvement of 30% of the students from non-Keck schools. There is a strong commitment to increasing the number of under-represented students in the Geoscience pipeline (this group includes African American, Hispanic, and Native American) and the new diversity initiative at the Keck Geology Consortium guarantees greater participation by this cohort. The Keck Consortium is dramatically increasing the number of under-represented student participation by several strategies including internal recruitment and external partners. The Keck Geology Consortium plays a leading role in the research training of promising students, and the majority of these students pursue a MSc and/or PhD in the geosciences. Thus the Consortium supplies the geoscience pipeline with bright, talented, well-trained students and many become leaders in the field. It is well known that research active faculty provide a successful and productive learning environment, and that student research at the undergraduate level provides students with the motivation, capability, and preparation for graduate school that typically leads to a productive career in the geosciences.