Large-scale Terrane Displacement in the Arctic: Evidence from Faults in the Northern Yukon

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The shapes of the continents are modified over time by a variety of tectonic processes including large-scale horizontal transport of crustal fragments. This project explores the idea that this process was important in shaping the current configuration of the North American Arctic region. The research team will investigate a major fault system - the Kaltag-Porcupine fault system - in northern Yukon, Canada to determine if it accommodated horizontal movement of a large portion of the Arctic region and, if so, when this occurred. This research project will not only further our understanding of large-scale transport of crustal fragments along continent-scale strike-slip systems, but also provide new insights into the tectonic evolution of the poorly understood Arctic region of North America, a region important for its natural resources. The study will promote international collaboration between academic researchers at two U.S. institutions, two Canadian and German universities, and government research agencies in both Germany, Canada, and the United States. The collaborative international effort will also generate research opportunities and training for undergraduate and graduate students at both Dartmouth College and the University of Iowa, as well as a series of public lectures and a new museum exhibit in the Upper Valley of New England.Recent models for the Paleozoic tectonic evolution of the Arctic highlight significant, yet poorly understood, margin-parallel transport of crustal fragments relative to the North American craton; however, very little is known about the hypothetical structures that accommodated these displacements. The goal of this research project is to study the Kaltag-Porcupine fault system of Yukon, Canada, a craton-bounding structure that potentially accommodated the displacement of Arctic Alaska and other Arctic terranes across the northern margin of Laurentia. The fault system was probably reactivated during the Mesozoic and Tertiary, but may be a much older early Paleozoic structure. The research team aims to determine if the structure separates geologic units with different histories and paleogeographic origins and if there is any evidence for Paleozoic displacement on the structure. This project will involve: 1) development of a large, stratigraphically-constrained provenance data set, consisting of sandstone petrography, large-N detrital zircon U/Pb geochronology and hafnium isotopes, and major and trace element geochemistry and neodymium isotopes on mudstone, from previously collected and new samples of late Neoproterozoic-Silurian strata in the North Slope subterrane and Yukon block of northwestern Canada; and 2) a detailed structural and geochronological examination of the Kaltag-Porcupine fault system in northern Yukon, Canada. This multidisciplinary project will fundamentally inform tectonic models for the evolution of the Arctic and northwestern margin of North America.