International Postdoctoral Fellows: Paleomagnetic Exploration of the Process of Eduction and Cooling of Deep- Seated Metamorphic Rocks Following Laurentian-Baltic Plate

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9403645 McEnroe This award is under the International Junior Investigator and Postdoctoral Fellows Program, which enables U.S. scientists and engineers to conduct three to twelve months of research abroad at research centers of proven excellence. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twelve-month postdoctoral research visit by Dr. Suzanne A. McEnroe of the University of Massachusetts at Amherst to work with Dr. Trond H. Torsvik at the Norwegian Geological Survey (NGU) on paleomagnetic exploration of the processes of education and cooling of deep-seated metamorphic rocks following Laurentian-Baltic plate collision in the Western Gneiss Region, Norway. Research on the paleomagnetism of metamorphic rocks is designed to determine the orientation of the earth's magnetic field at the time of formation of the protolith, at the time when new magnetic minerals grew during low-temperature metamorphism, or at the time when magnetic minerals cooled below the Curie temperature (580 degrees Celsius) or Neel temperature (670 degrees Celsius) following high-temperature metamorphism. The western gneiss region of the Scandinavian Caledonides in Norway contains a wide variety of rock types within the Baltic plate that were subducted to depths up to 100 km and heated to temperatures up to 750 degrees Celsius before being rapidly "educted" and cooled against overlying cooler remnants of the Laurentian plate. The acquisition of paleomagnetic vectors from the metamorphic rocks is made difficult by the factors of coarse grain size and fabric anisotropy, but numerous targets of opportunity are available in the form of apparently isotropic eclogites and basement gabbro masses with relict primary distributions of magnetic minerals. Using the superb equipment at the NGU, it is intended to use this paleomagnetic tool to enhance our unde rstanding of the relationships between metamorphic reactions, cooling deformation, time, and the acquisition of magnetic signatures in these deep- seated metamorphic rocks. The results of this research would contribute to overall understanding of deep-seated processes, rock-magnetic properties of these metamorphic rocks, and crustal history in a zone of continental collision. ***