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

由于我们对环北极地质学的认识不足，目前关于白垩纪时期美亚盆地开口的构造模型是有争议的。这种不确定性是由于缺乏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也是检验有关外来地壳碎片起源和演变的假设的关键，这些碎片现在已并入北美科迪勒拉造山带。 其中一些“可疑”的火山岩具有古生代和新元古代的基底，与劳伦大陆的西缘（北美西部）相比，它们记录了完全不同的演化历史。这些地壳碎片的起源难以捉摸，一直是地质文献中的一个长期问题。除了一些先前提出的模型，这些外来的珊瑚礁的起源，最近有人提出，他们出生在波罗的海和东部劳伦领域，随后迁移到西部劳伦作为一个中古生代加勒比/斯科舍式俯冲系统，形成之间的北方北美和西伯利亚夹带的结果。在这些流离失所的阿拉斯加人中，皮尔亚（北方埃尔斯米尔岛）和北极阿拉斯加离他们在波罗的海地区的假定家园最近。目前，我们正在对来自北极阿拉斯加北方埃尔斯米尔岛和育空地区的新元古代和早古生代岩石进行详细的地层学、古生物学、地球化学和年代学研究，以检验：1）最近提出的来自波罗的海的古生代外来生物西北通道模式; 2）SAYBIA-Rubia假说，该假说假定阿拉斯加北极的南半部与其他“可疑”的大陆形成了一个带状大陆，这些大陆在白垩纪之前一直是北美的外来物种;和3）北极阿拉斯加的北美起源。最后，在Pearya和北极阿拉斯加的新元古代和古生代地质的特点将约束模型的起源，外来的科迪勒拉山脉，并将提供地质背景重建白垩纪开口的美亚盆地。该项目是哈佛大学和爱荷华州大学的研究人员合作的成果。哈佛自然历史博物馆（HNHM）的矿物学和地质博物馆拥有美国首屈一指的陨石和矿物收藏品之一。HNHM每年约有33，000名学生组团参观，为学生介绍地球科学提供了一个独特的论坛。 目前正在HNHM开发一个关于北极地质的展览。展览将包括：1）在阿拉斯加国家野生动物保护区的西北布鲁克斯山脉、北方埃尔斯米尔岛和北极破冰船上探险的照片; 2）从这些地方的每一个地层中采集的岩石样本，包括北坡石油源岩和储集岩; 3）关于北极地质演变的教育展示。HNHM将提供一个儿童友好的显微镜和一个微软触摸桌，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。除了矿物学之外，还要扩大米高梅的规模？HNHM的教育展示了现代地球科学的综合性和令人兴奋的性质，特别是北极的地质演化，有可能影响到访问HNHM的33，000名学生中的一部分，以进行地球科学研究。该项目还将为培养两名博士生做出贡献。一个在哈佛大学，一个在爱荷华州大学，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.