Dr. Nick Swanson-Hysell
University of Minnesota

Topic: Rapid Mesoproterozoic plate motion stalled by the Grenvillian orogeny and the assembly of Rodinia

Academic host: Becky Flowers

Abstract: The paleogeography of Laurentia across the Mesoproterozoic-Neoproterozoic boundary is critical for reconstructing global paleogeography due to its central position in the supercontinent Rodinia. Abundant paleomagnetic poles with tight temporal constraints indicate rapid motion of Laurentia between 1,110 to 1,080 Ma. This motion has been interpreted to either be the result of true polar wander or due to differential plate tectonic motion. One test between these mechanisms is whether or not Laurentia's motion slowed associated with the onset of the collisional Grenvillian orogeny. New paleomagnetic data for Laurentia from 1,080 to 1,050 Ma and ca. 990 Ma indicates that Laurentia's rate of motion dropped by an order of magnitude associated with collisional orogenesis. These results indicate that Laurentia's rapid equatorward journey was the result of differential plate tectonic motion associated with the closure of the Unimos Ocean basin leading up to the assembly of Rodinia.