Collaborative Research: Origin of the Alexander Terrane in the Arctic Realm?

这个项目将测试这样一个假设，即阿拉斯加南部的大部分地区是沿着加拿大的北极边缘形成的，只有在相对较近的地质历史中才有运输到现在的位置。这样的位移历史与更传统的观点相反，传统观点认为，这些岩石和北美西部的大多数其他部分（如下加利福尼亚）是沿着大陆边缘向北移动的。它也不同于先前的说法，即这些岩石形成于古太平洋西部边缘，是北美真正的外来物种。幸运的是，最近的技术发展提供了一种技术，可以对这些可能的替代方案进行可靠的评估。这项技术包括确定移位岩石中的锆石晶体的年龄，以及美国西部、古太平洋西部边缘和加拿大北极地区的潜在相关岩石的锆石晶体年龄。年龄相近的锆石晶体的出现表明可能存在联系，而同一年龄的岩石中出现不同年龄的锆石晶体则与地理上的接近不一致。该项目将为两所大学的本科生和研究生提供参与研究项目的机会，该研究项目涉及前沿地区的实地研究和使用先进仪器的实验室分析。本项目涉及的主要活动包括：1。在阿拉斯加东南部的亚历山大地体和加拿大北极的皮尔亚地体的古生代进行地质实地研究和收集样品。这些研究将在阿拉斯加东南部的黄道带和一艘船上生活船（目前由亚利桑那大学运营）上进行，并在加拿大北极地区得到直升机的支持。2 .亚利桑那大学利用新型激光烧蚀-ICPMS系统（Nu HR ICPMS）和SEM系统（Hitachi 3400N和Gatan Chroma CL）测定碎屑锆石的U-Pb年龄和Hf同位素比值。将我们的新数据与来自环太平洋和环北极地区其他组合的U-Pb年龄和Hf同位素信息进行比较，以测试亚历山大地体的各种可能的位移模型。大部分的实地和实验室研究将由亚利桑那大学和爱荷华大学的研究生进行。本科生将作为现场助理参与，并酌情提供可能的高级论文类型项目。

This project will test the hypothesis that much of southern Alaska formed along the Arctic margin of Canada, with transport to its present position only in the relatively recent geologic past. Such a displacement history is counter to the more traditional view that these rocks, and most other portions of western North America (e.g., Baja California), have moved northward along the continental margin. It also differs from previous suggestions that these rocks formed along the western margin of the paleo-Pacific and are truly exotic to North America. Fortunately, recent technological developments have provided a technique that will provide a robust evaluation of these possible displacement scenarios. The technique involves the determination of ages of zircon crystals in the displaced rocks and in potential correlatives in the western US, along the western margin of the paleo-Pacific, and in the Canadian Arctic. The occurrence of similar ages would suggest potential linkages, whereas the occurrence of different ages of zircon crystals in rocks of the same age would be inconsistent with geographic proximity. This project will provide opportunities for undergraduate and graduate students at two universities to participate in a research project that involves both field studies in frontier regions and laboratory analyses utilizing sophisticated instrumentation. Primary activities involved in this project will include:1. Conducting geologic field studies and collecting samples from Paleozoic strata of the Alexander terrane in southeast Alaska and the Pearya terrane in the Canadian Arctic. These studies will be based from zodiacs and a live-aboard boat (presently operated by the University of Arizona) in SE Alaska and with helicopter support in the Canadian Arctic.2. Determining U-Pb ages and Hf isotope ratios of detrital zircons utilizing a new Laser Ablation-ICPMS system (Nu HR ICPMS) and SEM system (Hitachi 3400N and Gatan Chroma CL) at the University of Arizona.3. Comparison of our new data with U-Pb ages and Hf isotope information from other assemblages in the circum-Pacific and circum-Arctic realms in an effort to test various possible displacement models for the Alexander terrane. Much of the field and lab research will be conducted by graduate students at the University of Arizona and the University of Iowa. Undergraduate students will be involved as field assistants, with possible senior-thesis-type projects available as appropriate.