Collaborative Research: Displacement history of the Pearya terrane, Ellesmere Island - evaluating a strike-slip origin for the Canadian Arctic margin

该项目是对构成北美最北端陆地的埃尔斯米尔岛Pearya岩的基底岩石进行结构、岩石学和地质年代学研究。这种构造活动与斯瓦尔巴特群岛和格陵兰岛的大陆地壳具有地质上的密切关系。据推测，Pearya山是沿着加拿大北极边缘地壳碎片被板块构造过程移位的最好例子。 一个被提出的关于皮尔雅山脉起源的构造模型（古生代西北通道模型）假设，构成科迪勒拉山脉西北部（例如阿拉斯加）的许多外来或长途旅行的地质断层起源于格陵兰岛和斯堪的纳维亚半岛共享的加里东造山带，随后在大约4亿年前沿着走滑断层向西移动到现在的位置。 由于缺乏关于Pearya的时间和运动意义的文献，严重限制了对北美北极边缘构造演化的理解，为最近的模型留下了空间，这些模型声称Pearya是静止的，而不是构造位移的结果。 该项目包括实地观察和样本收集从偏远的南部边界的Pearya的，将用于测试这些模型。 该项目是德国联邦地球科学与自然资源研究所组织的2017年环北极构造事件考察的一部分，该研究所将为实地工作提供后勤支持。 该项目将涉及来自五个国家的科学家的国际合作。除了该项目的科学贡献外，该研究还将有助于培养重要的科学，技术，工程和数学（STEM）学科的研究生和本科生，这对于增强美国劳动力的兼容性非常重要。该项目还将有助于扩大STEM中代表性不足的群体。研究成果将通过讲座与公众分享，并将在同行评审的科学文献和专业协会会议上发表。了解北美北极边缘的地质演化对于了解与北极地区相关的重要科学，政治和经济问题至关重要。该项目由美国国家科学基金会国际科学与工程办公室共同资助，其最终目标是建立一个地层、构造和变质框架，以研究皮尔雅河复杂南部边界的演化。 这项研究需要综合运动学，岩石年代学和氩-氩热年代学分析的结晶基底和主要故障在南部Pearya的边缘，和详细的地层比较，通过砂岩岩相学，碎屑锆石铀-铅和铪分析，和主要，微量元素和钕同位素地球化学的泥岩的整个边界。 虽然加拿大北极边缘经常被引用为大规模平移的例子，但对可能容纳如此深刻位移的结构知之甚少。 该项目将根据与平移挤压相关的结构评估可能的走滑构造，这可能与早期的直线收缩观测相一致。这项研究的结果将提供关键的时间上的变质作用的年龄和早期韧性历史的剪切带，以通过普遍的叠印看到。 主要调查人员还将评估不同断块中重叠组合的地层学，以确定它是否是一个单一的组合，或者实际上是空间上分离的沉积体系的时间相关物。 通过生成与地质学相关的强大数据集，该项目将有助于区分目前存在的PearyaMecle和北极更大的构造发展的不同模型。

This project is a structural, petrologic and geochronologic study of basement rocks that comprise the Pearya terrane of Ellesmere Island, which forms the northernmost landmass of North America. This tectonic terrane has geologic affinities with continental crust in Svalbard and Greenland. It is postulated that the Pearya terrane is the best example along the Canadian Arctic margin of a crustal fragment that has been displaced by plate tectonic processes. A proposed tectonic model for the origin of the Pearya terrane (the Paleozoic Northwest Passage model) postulates that many exotic or far-travelled geologic terranes that make up the northwestern Cordillera (e.g. Alaska) originated in the Caledonian orogenic belt shared by Greenland and Scandinavia, and subsequently traveled westward on a strike-slip fault to their current location about 400 million years ago. The lack of documentation on the timing and movement sense of the Pearya terrane severely limits understanding of the tectonic evolution of the Arctic margin of North America, leaving room for recent models that claim Pearya was stationary and was not the result of tectonic displacement. This project includes field observations and sample collection from remote southern boundary of the Pearya terrane that will be used to test these models. The project is part of the 2017 Circum-Arctic Structural Events Expedition organized by the German Federal Institute for Geosciences and Natural Resources, who will provide logistical support for the fieldwork. The project will involve international collaboration with scientists from five countries. In addition to the scientific contributions of the project, the study will contribute to training of graduate and undergraduate students in an important science, technology, engineering and mathematics (STEM) discipline, which is important in contributing to the enhanced compatibility of the U.S. workforce. The project will also contribute to broadening of underrepresented groups in STEM. Research results will be shared with the public through lectures and will be published in the peer reviewed scientific literatures and presentations at professional society meetings. Understanding the geological evolution of the North American Arctic margin is critical to informing important scientific, political and economic issues associated with the Arctic region. This award is cofunded by the NSF Office of International Science and Engineering.The ultimate goal of this project is to establish a stratigraphic, structural and metamorphic framework for the evolution of the complex southern boundary of the Pearya terrane. The study entails integrated kinematic, petrochronologic and argon-argon thermochronologic analysis of the crystalline basement and major faults at the southern Pearya terrane margin; and detailed stratigraphic comparison across the terrane boundary through sandstone petrography, detrital zircon uranium-lead and hafnium analysis, and major, trace element and neodymium isotope geochemistry on mudstone. Although the Canadian Arctic margin is often cited as an example of large magnitude terrane translation, little is known about the structures that may have accommodated such profound displacement. The project will evaluate possible strike-slip tectonics in light of structures associated with transpression, which may reconcile the earlier observations of straight contraction. The results of this study will provide critical timing on the age of metamorphism and the early ductile history of the shear zones in order to see through the pervasive overprinting. The principal investigators will also evaluate the stratigraphy of the overlap assemblage in different fault blocks to determine whether it is a single assemblage or, in fact, time correlatives of spatially separate depositional systems. By producing a robust data set tied to the geology, this project will help discriminate among the disparate models that currently exist for the Pearya terrane and the larger tectonic development of the Arctic.