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

University Of Iowa, Iowa City IA

Investigators

Abstract

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.