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

阿拉斯加北极地区布鲁克斯山脉褶皱和冲断带南翼的结构体系和演化

• 批准号: 1624582
• 负责人: Elizabeth Miller
• 金额: $ 17.22万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1624582&HistoricalAwards=false
• 关键词: Structural; Architecture; Evolution; Southern; Flank

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.

一个与断层有关的大变形带，被称为片岩带，沿着阿拉斯加北部布鲁克斯山脉的南侧，东西延伸600多公里。该断裂带在两侧沉积盆地的形成中发挥了重要作用，即南部的育空-科尤库克盆地和北部的科尔维尔盆地。它也是分隔阿拉斯加南部和阿拉斯加北部的主要构造，阿拉斯加南部的地质历史与太平洋板块边缘有关，阿拉斯加北部的历史与北冰洋板块构造有关。尽管它的物理范围令人印象深刻，但关于它的确切年龄以及关于它为什么和如何发展的假设仍存在争议。该项目将研究该断裂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物流。这项拟议中的研究代表了对基础科学的贡献，它将提高我们对北极地质的理解，北极是地球上仅存的边疆之一。目前全球对北极的兴趣使该地区成为国际合作的绝佳场所，并为研究生提供了从事实地研究，学习最先进的分析技术和建立职业生涯的独特机会。培养北极地球科学和国际合作方面的研究生有助于为美国，特别是在北极地区，提供多样化的，具有全球竞争力的STEM（科学，技术，工程和数学）劳动力。在北极国家根据国际条约规划其近海延伸经济区之际，国际交流与合作是美国的首要任务。拟议的研究还将产生地图和数据汇编，这些地图和数据汇编将对与自然资源有关的广泛的社会各方面有用，包括矿物和碳氢化合物，潜在的地质灾害和土地利用，以及有助于了解北极之门国家公园的地质情况。加深对北极地区的了解对国家安全考虑也很重要。北极阿拉斯加的布鲁克斯山脉造山带北侧为侏罗纪至早白垩世的地壳缩短带，其典型的冲断带结构由叠瓦状被动边缘层序和异源洋弧层序组成。布鲁克斯山脉的构造更深，多变质的核心现在被理解为包括北极卡利多尼德山脉和波罗的海蒂马尼德山脉的一部分，由于北冰洋的开放而转移到它们现在的位置。片岩带被定义为一个渗透变形带，其结构和年龄（基于40Argon/39Argon地质年代学）与以往的工作者有显著不同的解释。我们提出的工作将测试假设，并解决有关这个带的年龄和起源的问题。地质作图加上细观和微观构造工作，包括石英晶格优选方向的研究，将允许沿走向比较带内的变形，并确定它是代表逆冲还是正常意义上的剪切。利用40Argon/39Argon方法的热年代学样带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标记。磷灰石裂变径迹定年将使我们能够确定大规模新生代构造的几何形状，这些构造导致了片岩带岩石的显著和独特的暴露。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五年的运动共同努力，并将为广泛的国际努力作出贡献，重点是了解北冰洋的起源。它还为我们提供了一个机会，与一项涉及部署地球望远镜的重大科学任务合作。这将最终为这项研究提供岩石圈背景。