HR: 1340h
AN: U33A-0026    [Abstracts]
TI: Rapid, Coherent Apparent Polar Wander in the Terminal Neoproterozoic - Early Cambrian?
AU: * McCausland, P J
EM: pjam@umich.edu
AF: University of Michigan, Dept. of Geological Sciences, 2534 C.C. Little Blg., Ann Arbor, MI 48109 United States
AU: Van der Voo, R
EM: voo@umich.edu
AF: University of Michigan, Dept. of Geological Sciences, 2534 C.C. Little Blg., Ann Arbor, MI 48109 United States
AB: Rapid apparent polar wander (APW) has been documented for several continents in the Precambrian-Cambrian transition period. Recent paleomagnetic results from Laurentia and Baltica confirm that rapid and coherent APW occurred for these continents, taking them from the polar region at ca. 580 Ma to near-equatorial latitudes by the start of the Cambrian. Similarly large (~90 degree) Vendian-Cambrian APW tracks for Siberia and West Gondwana are evident, although they are not as well constrained, especially in age. Coeval results from Australia show no APW, however. The rapid latitudinal shift for Baltica, Laurentia and perhaps Amazonia occurred at rates in excess of 20 cm/yr, suggesting that these continents were drifting on the same fast-moving plate and/or were recording significant true polar wander (TPW) during the terminal Neoproterozoic. In the Quebec-New England region of Laurentia, 570-550 Ma rift magmatism shows evidence of having had a plume source, which, assuming the fixity of plumes may indicate that TPW was the major contributor to the observed large and rapid motion of Laurentia during that period. Conversely, no record of TPW is present in the Australian data. Regardless of the magnitude of TPW contribution, the long APW tracks of Laurentia, Baltica, Siberia and perhaps West Gondwana appear to be a robust feature of the terminal Neoproterozoic.
DE: 9619 Precambrian
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8149 Planetary tectonics (5475)
DE: 8157 Plate motions--past (3040)
DE: 1525 Paleomagnetism applied to tectonics (regional, global)
SC: Union [U]
MN: 2004 AGU Fall Meeting