HR: 0800h
AN: T31A-1262    [Abstracts]
TI: Modeling Supercontinent Cycles in 3D Spherical Convection Simulations With Multiple Continents
AU: * Phillips, B R
EM: benp@princeton.edu
AF: Princeton University, Department of Geosciences Guyot Hall, Washington Road, Princeton, NJ 08544 United States
AU: Bunge, H
EM: bunge@lmu.de
AF: Ludwig Maximilians University, Earth and Environmental Sciences Geophysics Section Theresienstr. 41/IV, Munich, 80333 Germany
AB: In 1966 J. Tuzo Wilson suggested that the Atlantic Ocean basin had closed and then reopened, a process now commonly termed the Wilson Cycle. Since then, numerous paleomagnetic studies have shown that Wilson's original idea may be extended to describe a global cycle, punctuated by the periodic formation of supercontinents such as Pangea, Rodinia, and Nuna, separated by time scales of several hundred million years (Myr). It is generally accepted that these motions are coupled to large scale mantle convection. Early two dimensional (2D) mantle convection models demonstrated the dynamic feasibility of such supercontinent cycles. However, fully 3D spherical mantle convection models incorporating multiple continents have yet to be explored. Here we present the first high resolution, 3D spherical mantle convection models with multiple continents. A global grid spacing of $\sim$50 km permits us to model vigorous convection at Rayleigh number 10$^7$. We study models incorporating between two and ten continents in predominantly internally heated flow with radially stratified viscosity. From these models we find that continents aggregate and disperse cyclically, with periods of several 100 Myr. Supercontinents remain intact for roughly 200 Myr. Moreover, the presence of multiple continents promotes the development of mantle thermal heterogeneity on the longest length scales (spherical harmonic degrees 1 and 2) in some models. These results agree well with geologic observations and place dynamic constraints on global mantle flow models.
DE: 8110 Continental tectonics--general (0905)
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8155 Plate motions--general
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting