Collaborative Research: RUI: Translation and Accretion of the Yakutat Microplate and Prince William Terrane, Alaska

北美科迪勒拉山脉是通过形成，加积和平移的数量和这种组装大部分发生在白垩纪以来。从那时起，由于太平洋板块与北美板块的相对运动，大部分的西太平洋平移都是向北的。尽管几十年来对印第安人的运动和翻译进行了调查，但这些印第安人的起源以及他们在成为阿拉斯加印第安人融合的一部分之前旅行了多远仍然是未知的。该项目带来了新的分析技术，以承担这个问题的重点是雅库塔特河，这是现在与阿拉斯加南部碰撞驱动楚加奇山脉的隆起。这项研究测试了雅库特人起源于太平洋西北部南部的想法，并在与阿拉斯加南部相撞之前平行于大陆边缘移动。该项目将通过以下方式促进预期的社会成果：让代表性不足的少数群体的学生参与STEM，通过为国家公园和国家森林编制小册子，通过本科生积极参与主要是本科院校的研究，培养具有全球竞争力的STEM人才。构成阿拉斯加大部分地区的印第安人的拼贴画是有争议的，包括楚加奇和威廉王子的印第安人，以及雅库特印第安人。一些情景设想了楚加奇和威廉王子陨石坑或多或少的位置，而其他情景（最初基于古地磁数据）则建议长距离运输（3000公里）。这些观点的差异是深刻的，但在科迪勒拉，走滑断层上的大规模平移可能是一个基本的、未被重视的过程。碎屑锆石的高精度和高容量U/Pb和裂变径迹测年集中了研究问题的透镜，通过对沿着科迪勒拉边缘的单元进行地质比较，可以做出严格的预测，以更好地了解平移历史和总偏移量。初步数据显示，关于楚加奇-威廉王子海峡和雅库特海峡碰撞区的一些假设需要修正，包括：（1）雅库特海峡的浊积岩可能不是以前假设的楚加奇海峡和威廉王子海峡的一部分;（2）雅库特海峡的玄武岩基底可能形成于沿着北美边缘的扭张环境。这里测试的假设是，运输雅库特的阿拉斯加州导致了在太平洋西北部的截断边缘，夏洛特皇后-费尔韦瑟断层系统的滑动可能部分容纳了1800公里的右旋平移，这可能是最长的偏移在科迪勒拉断层的地质关系。本研究的分析方法涉及使用几种技术分析碎屑锆石，其中一些是新的和创新的。这些方法包括：（a）碎屑锆石的U/Pb，以确定最大沉积年龄和物源，包括针对前寒武纪来源;（B）碎屑锆石的裂变径迹，以提供与折返作用直接相关的冷却年龄，包括双重定年颗粒（裂变径迹和U/Pb）;（c）碎屑的拉曼光谱学，提供辐射损害日期;（d）碎屑锆石中的Hf同位素，提供地壳特征;以及（e）核缘定年，以确定火成岩和变质边缘的年代。确定碎屑锆石的辐射损伤年龄是一种新的方法，有望为碎屑研究提供更深入的见解。虽然锆石是这项工作的核心，使用地球化学和岩石学的学生项目将集中在更好地了解与这些岩石有关的火成岩的发展。

The North American Cordillera was assembled through the formation, accretion, and translation of a number of terranes and much of this assembly has occurred since the Cretaceous. Since this time, most of the terrane translation was northward due to the relative motion of Pacific plates with North America. Despite decades of investigations on terrane movement and translation much remains unknown about where these terranes originated and how far they traveled before becoming part of the amalgamation of terranes in Alaska. This project brings new analytical techniques to bear on this problem focusing on the Yakutat terrane, which is now colliding with southern Alaska driving the uplift of the Chugach Range. This research tests the idea that the Yakutat terrane originated far to the south in the Pacific Northwest and moved parallel to the continental margin before colliding with southern Alaska. The project would advance desired societal outcomes by participation of students from underrepresented minorities in STEM, increased public scientific literacy and public engagement with STEM through development of brochures for the National Parks and National Forests and development of a diverse, globally competitive STEM workforce through active participation of undergraduate students in research at primarily undergraduate institutions.The development and translation history of the collage of terranes that make up most of Alaska are debated, including the Chugach and Prince William terranes, and Yakutat terrane. Some scenarios envision a setting for the Chugach and Prince William terranes that was more or less in place, while other scenarios (originally based on paleomagentic data) suggest long transport (3000 km). The difference in these ideas is profound, but large-scale translation of terranes on strike-slip faults may be a fundamental and underappreciated process in the Cordillera. High-precision and high-volume U/Pb and fission track dating of detrital zircon has focused the lens with which the problem can be examined, and rigorous predictions can be made by making geological comparisons of units along the Cordilleran margin to better understand translation history and total offset. Preliminary data show a number of assumptions about the Chugach-Prince William terrane and Yakutat terrane collision zone need to be revised, including: (1) turbidites of the Yakutat terrane may not be part of the Chugach and Prince William terranes as previously assumed; and (2) the basaltic basement of the Yakutat terrane may have formed in a transtensional environment along the North American margin. The hypothesis tested here is that transport of the Yakutat terrane to Alaska resulted in a truncated margin in the Pacific Northwest, and slip on the Queen Charlotte-Fairweather fault system may have partly accommodated the 1800 km of dextral translation, which may be one of the longest offsets shown by geological relationships on faults in the Cordillera. The analytical approach of this research involves the analysis of detrital zircon using several techniques, some of which are new and innovative. These approaches include: (a) U/Pb of detrital zircon to determine maximum depositional age and provenance, including targeting Precambrian sources; (b) fission track on detrital zircons to provide cooling ages directly related to exhumation, including double dating grains (fission track and U/Pb); (c) Raman spectroscopy on detrital to provide radiation damage dates; (d) Hf isotopes in detrital zircon to provide crustal signature; and (e) core-rim dating to date igneous and metamorphic rims. Determining radiation damage ages on detrital zircon is a new approach that promises to provide deeper insight into detrital studies. Although zircon is central to this effort, student projects that use geochemistry and petrology will focus on better understanding the development of the igneous rocks associated with these terranes.