Structural Architecture and Evolution of the Southern Flank of the Brooks Range Fold and Thrust Belt, Arctic Alaska

在阿拉斯加北方的布鲁克斯山脉的南侧，有一个由断层引起的广泛变形区，称为片岩带，东西延伸沿着600多公里。 这个断裂带在形成两侧的沉积盆地、南部的育空-科尤库克盆地和布鲁克斯山脉北部的科尔维尔盆地方面发挥了重要作用。 它也是将阿拉斯加南部与北方阿拉斯加分开的主要结构，阿拉斯加南部的地质历史与太平洋板块边缘有关，而阿拉斯加北部的历史与北冰洋的板块构造有关。 尽管它的物理范围令人印象深刻，但关于它的确切年龄和关于它为什么以及如何发展的假设的问题仍然存在争议。该项目将研究该断层带的地质和变形历史，与瑞典的一个旨在了解北极地区地质的国际项目共享后勤。这项拟议中的研究代表了对基础科学的贡献，将提高我们对北极地质的理解，北极是地球上最后剩下的前沿之一。目前全球对北极的兴趣使该地区成为国际合作的绝佳竞技场，并为研究生提供了一个独特的机会，可以从事实地研究，学习最先进的分析技术并建立自己的职业生涯。 培训研究生在北极地球科学和国际合作有助于多样化，全球竞争力的干（科学，技术，工程和数学）劳动力为美国，特别是在北极。 国际交流与合作是美国的首要任务，因为北极国家根据国际条约规划其离岸经济区。 拟议的研究还将制作地图和数据汇编，这些地图和数据汇编将有助于社会各阶层广泛了解自然资源，包括矿物和碳氢化合物、潜在的地质灾害和土地使用，并有助于了解北极之门国家公园的地质情况。更好地了解北极地区对国家安全考虑也很重要。 沿着其北方一侧，北极阿拉斯加的布鲁克斯山脉造山带是一个侏罗纪至早白垩世地壳缩短带，其特征是典型的冲断带结构，由叠瓦状被动边缘序列和异地洋弧序列组成。 布鲁克斯山脉的结构更深的多变质核现在被理解为包括北极加里东和波罗的海Timanides的部分，由于北冰洋的开放而转移到目前的位置。 片岩带被定义为渗透变形带，其组构和年龄（基于40 Ar/39 Ar地质年代学）被以前的工作者以显著不同的方式解释。 我们提出的工作将测试假设，并解决有关该带的年龄和起源的问题。 地质测绘与中、微观构造工作相结合，包括石英晶格优选取向的研究，将允许对带内变形进行沿着走向比较，并确定它是代表逆冲还是正向剪切。采用40 Ar/39 Ar方法的热年代学断面和变质锆石生长的铀-铅定年将对变形和变质作用的年龄进行括号。磷灰石裂变径迹测年将使我们能够确定大规模新生代结构的几何形状，这些结构导致了片岩带岩石的显着和独特的暴露。 拟议的工作提供了一个独特的机会，可以与瑞典研究理事会资助的一项为期5年的运动共同努力，它将有助于广泛的国际努力，重点是了解北冰洋的起源。 它还为我们提供了一个机会，与一个重大的科学使命，涉及部署地球镜？美国阿拉斯加州的可移动阵列，这将最终提供一个岩石圈的背景下，这项研究。

A broad zone of fault-related deformation, called the Schist Belt, stretches East-West for more than 600 kilometers along the southern side of the Brooks Range in northern Alaska. This fault zone played a fundamental role in the formation of flanking sedimentary basins, the Yukon-Koyukuk Basin to the south and the Colville Basin to the north of the Brooks Range. It is also the main structure separating southern Alaska, with a geologic history tied to the Pacific plate margin, from northern Alaska, whose history is tied to plate tectonics in the Arctic Ocean. Despite its impressive physical extent, questions about its exact age and hypotheses about why and how it developed are debated. This project will study the geology and deformation history of this fault zone, sharing logistics with an international Swedish project aimed at understanding the geology of the Arctic region. The proposed research represents a contribution to basic science that will improve our understanding of the geology of the Arctic, one of the last remaining frontiers on earth. Current global interest in the Arctic makes this region a superb arena for international collaborations and offers a unique opportunity for graduate students to engage in field-based research, learn state-of-the-art analytical techniques and build their careers. Training graduate students in Arctic geoscience and international collaboration contributes to a diverse, globally competitive STEM (science, technology, engineering and mathematics) workforce for the U.S., particularly in the Arctic. International communication and collaboration is a top priority for the U.S. as Arctic nations chart their offshore-extended economic zones based on international treaties. The proposed research will also produce maps and data compilations that will represent contributions that will be useful to a broad cross-section of society as related to natural resources, including both mineral and hydrocarbons, potential geologic hazards and land-use, as well as contributing to knowledge of the geology of the Gates of the Arctic National Park. Greater understanding of the Arctic region is also important to national security considerations. Along its northern side, the Brooks Range orogen of Arctic Alaska is a Jurassic to Early Cretaceous belt of crustal shortening characterized by a classic thrust belt architecture consisting of imbricated passive margin sequences and allochthonous oceanic arc sequences. The structurally deeper, polymetamorphic core of the Brooks Range is now understood to include portions of the Arctic Caledonides and the Baltic Timanides, translated to their current position by the opening of the Arctic Ocean. The Schist Belt is defined as a zone of penetrative deformation whose fabrics and age (based on 40Argon/39Argon geochronology) are interpreted in remarkably different ways by previous workers. Our proposed work will test hypotheses and address questions about the age and origin of this belt. Geologic mapping coupled with meso- and microstructural work, including the study of quartz lattice preferred orientations, will permit along strike comparisons of deformation within the belt and determine if it represents thrust or normal sense shear. Thermochronology transects using 40Argon/39Argon methods and Uranium-Lead dating of metamorphic zircon growth will place brackets on the age of deformation and metamorphism. Apatite fission track dating will allow us to define the geometry of large-scale Cenozoic structures that led to the remarkable and unique exposures of Schist Belt rocks. The proposed work provides a unique opportunity to join efforts with a 5-year campaign funded by the Swedish Research Council and it will contribute to the broad international effort focused on the understanding the origin of the Arctic Ocean. It also offers us the opportunity to collaborate with a substantial scientific mission involving the deployment of EarthScope?s Transportable Array across the state of Alaska, which will ultimately provide a lithospheric context for this study.