Collaborative Research: Comparative Studies of Circum-Arctic Neoproterozoic-Paleozoic Terranes

由于我们对环北极地质学缺乏了解，目前关于美洲大陆盆地白垩纪开放的构造模型存在争议。这种不确定性源于缺乏来自北美北极大陆边缘偏远地区的实地观测和数据。更好地了解环北极地质学对于检验与目前并入北美科迪勒拉造山带的外来地壳碎片的起源和演化有关的假说也至关重要。其中一些可疑的地体具有古生代和新元古代的基底，与劳伦蒂亚西部边缘(北美西部)相比，它们记录了完全不同的演化史。在地质文献中，这些地壳碎片的来源一直是一个难以捉摸的问题。除了以前提出的一些关于这些奇异地体起源的模型外，最近还提出它们出生在波罗的海和东部劳伦西亚地区，后来由于它们被北美北部和西伯利亚之间形成的中古生代加勒比/斯科舍式俯冲系统缠绕而迁移到劳伦西亚西部。在这些流离失所的地体中，皮利亚(北埃尔斯米尔岛)和北极阿拉斯加是距离它们在波罗的海地区所谓的故乡最近的。我们目前正在整合对北埃尔塞梅尔岛、北极阿拉斯加和育空地区新元古代和早古生代岩石的详细地层学、古生物学、地球化学和地质年代学研究，以提供以下测试：1)最近提出的古生代波罗的海奇异地体西北通道模型；2)SAYBIA-Rubia假说，该假说认为北极阿拉斯加南半部与其他“可疑”地体形成带状大陆，直到白垩纪增加；以及3)北极阿拉斯加起源于北美。最终，对皮亚和北极阿拉斯加新元古代和古生代地质的描述将制约外来科迪勒地体的起源模式，并将为重建美洲盆地白垩纪的开放提供地质背景。该项目是哈佛大学和爱荷华大学的研究人员共同努力的成果。哈佛自然历史博物馆(HNHM)的矿物和地质博物馆收藏了美国最重要的陨石和矿物收藏品之一。HNHM每年有大约33,000名学童成群结队地访问，这是一个向学生介绍地球科学的独特论坛。HNHM目前正在开发一个关于北极地质学的展览。展览将包括：1)前往埃尔斯米尔岛北部布鲁克斯山脉的阿拉斯加国家野生动物保护区探险的照片；2)这些地点每个地点地层的岩石样本，包括北坡石油源岩和储集岩；3)关于北极地质演化的教育展览。HNHM将提供适合儿童使用的显微镜和微软触摸台，使学生能够与北极板块构造重建的动画互动，并放大北极卫星和地质数据。除了矿物学，将米高梅S的教育展示扩大到现代地球科学，特别是北极地质演化的综合性和激动人心的性质，有可能影响到参观HNHM学习地球科学的33,000名学生中的一部分。该项目还有助于培训两名博士生，一名在哈佛大学，一名在爱荷华大学，并为这两所大学的本科生培训提供支持。

Current tectonic models for the Cretaceous opening of the Amerasia Basin are controversial due to our poor understanding of circum-Arctic geology. This uncertainty is derived from a lack of field-based observations and data from remote portions of the North American Arctic continental margins. A better understanding of circum-Arctic geology is also critical to testing hypotheses related to the origin and evolution of exotic crustal fragments now incorporated within the Cordilleran orogen of North America. Some of these "suspect" terranes have Paleozoic and Neoproterozoic basement that record completely different evolutionary histories in comparison to the western margin of Laurentia (western North America). The elusive origination of these crustal fragments has remained a longstanding question in the geological literature. In addition to a number of previously proposed models for the origin of these exotic terranes, it has recently been proposed that they were born in the Baltic and eastern Laurentian realm and subsequently migrated to western Laurentia as a result of their entrainment in a mid-Paleozoic Caribbean/Scotia-style subduction system that formed between northern North America and Siberia. Of these displaced terranes, Pearya (Northern Ellesmere Island) and Arctic Alaska are the closest to their putative homeland in the Baltic realm. We are currently integrating detailed stratigraphic, paleontological, geochemical, and geochronological studies on Neoproterozoic and early Paleozoic rocks from northern Ellesemere Island, Arctic Alaska, and the Yukon to provide tests for: 1) The recently proposed model for the Paleozoic northwest passage of exotic terranes from their formation in Baltica; 2) The SAYBIA-Rubia hypothesis, which posits that the southern half of Arctic Alaska formed a ribbon continent with other "suspect" terranes that was exotic to North America until accretion in the Cretaceous; and 3) A North American origin for Arctic Alaska. Ultimately, the characterization of the Neoproterozoic and Paleozoic geology in Pearya and Arctic Alaska will constrain models for the origins of exotic Cordilleran terranes and will provide the geological background for reconstructing the Cretaceous opening of the Amerasian Basin. The project is a collaborative effort between researchers at Harvard University and the University of Iowa. The Mineralogical and Geological Museum at the Harvard Natural History Museum (HNHM) hosts one of the premier meteorite and mineral collections in the United States. HNHM is visited annually by approximately 33,000 school children in groups, presenting a unique forum to introduce students to the Geosciences. An exhibit on the geology of the Arctic is currently being developed at the HNHM. The exhibit will include: 1) photographs from expeditions in the Alaska National Wildlife Reserve of the NW Brooks Range, Northern Ellesmere Island, and on Arctic Icebreakers; 2) rock samples from formations at each of these localities including the North Slope oil source and reservoir rocks; and 3) educational displays about the geological evolution of the Arctic. The HNHM will provide a kid friendly microscopes and a Microsoft touch-table that will enable students to interact with animations of Arctic plate tectonic reconstructions and zoom in on Arctic satellite and geological data. Beyond mineralogy, expanding the MGM?s educational displays to the integrative and exciting nature of modern Geosciences, particularly the geological evolution of the Arctic, has the potential to influence a portion of the 33,000 students who visit the HNHM to pursue studies in the Geosciences. The project is also contribute to the training of two Ph.D. students, one at Harvard and one at the University of Iowa, and is providing support for training of undergraduate students at both universities.