Intellectual merit: Numerical and laboratory simulations suggest that the dynamics of the geodynamo differ inside and outside the tangent cylinder, that imaginary cylinder parallel to Earth's spin axis and tangent to the solid inner core. The High Arctic provides an ideal opportunity to investigate such processes through the collection of paleomagnetic and paleointensity data. The Principal Investigator has recently discovered a geomagnetic reversal transition recorded by Late Cretaceous Arctic lavas (the site was well within the tangent cylinder during emplacement of the lavas). He will sample this fortuitous occurrence to define the pre, post, and transitional field. Directions will be based on paleomagnetic analyses of whole rock samples, and paleointensity on Thellier analyses of single plagioclase crystals separated from the lavas. These rocks are also important for understanding the tectonic evolution of the Arctic Ocean, its margins, the potential connection with the High Arctic (Strand Fiord) large igneous province and the role of mantle plumes. Finally, vertebrate fossils from the same stratigraphic sequences have yielded important polar paleoclimate information. The Principal Investigator will conduct a multidisciplinary study of these topics linked by a common field approach: high resolution sampling of well-defined High Arctic stratigraphic sections. Volcanic rocks will be sampled for paleomagnetism, geochronology and geochemistry, whereas fossils will be collected to better characterize Late Cretaceous-Paleogene polar temperatures.
Broader impacts of the proposed research: The Principal Investigator expects that the definition of a geomagnetic reversal recorded in lavas from a site within the tangent cylinder will be of interest to a broad range of scientists interested in core processes, while further determinations of the nature and age of these rocks will be important for those interested in the tectonic development of the Arctic Ocean and its margins. In addition, the study of vertebrate fossils associated with these volcanic rocks will be of interest to the paleoclimate community. This project will support a Ph.D. thesis and the studies of several undergraduate students. Undergraduates typically take part in the field work, and many conduct analyses of samples in the laboratory through independent study projects and undergraduate senior theses. He also plans outreach activities by presenting the findings to Arctic (Nunavut) communities.
