HR: 1340h
AN: T13A-0441    [Abstracts]
TI: A Little Theory, a Tomography Model, a List of Hotspots, and GMT
AU: * King, S D
EM: sking@purdue.edu
AF: Purdue University, Dept of Earth and Atmos. Sciences 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 United States
AB: Small-scale, or edge driven convection has been proposed as an alternative mechanism for hotspot volcanism. Using two theoretical results from mantle dynamics: 1) the endothermic spinel to perovskite plus ferro-periclase phase boundary is an effective barrier to short-wavelength convection (Tackley, 1995), and 2) the most unstable mode of convection has a horizontal wavelength √2 times the depth of the convecting cell (e.g., Turcotte and Schubert, 1982), I search for hotspots within 600-1000~km of the fast seismic velocity anomalies in the 100-200~km depth range in mantle tomographic models. These fast anomalies form the cores of the stable continents. I group hotspots into a class that has the potential to be explained by small-scale convection and a class that requires an alternate explanation. With the possible exception of Iceland, the list of potential small-scale convection hotstops does not contain any of the hotspots that Courtillot et al. (2003) classify as `primary.' With the exeption of the Canary Islands and Eifel, the list of potential small-scale convection hotstpots does not contain and of the deep-rooted hotspots identified by Montelli et al. (2003) interpreting their tomographic results. I will discuss the exeptions and the hotspots that do not fit into the deep or small-scale classifications. Courtillot, V., Davaille, A., Besse, J., and Stock, J., 2003, Three distinct types of hotspots in the Earth's mantle, Earth Planet. Sci. Lett., 205, 295-308. Montelli, R., Nolet, G., Dahlen, F. A., Masters, G., Engdahl, E., R., and Hung, S.-H., 2003, Finite-frequency tomography reveals a variety of plumes in the mantle, Science Express, 10.1126/science.1092485 Tackely, P. J., 1995, On the penetration of an endothermic phase transition by upwellings and downwellings, J. Geophys. Res., 100, 15,477-15,488. Turcotte, D.L. and G. Schubert, 1982, Geodynamics: Applications of Continuum Physics to Geological Problems, 450 pp. J. Wiley and Sons, New York.
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
DE: 8137 Hotspots, large igneous provinces, and flood basalt volcanism
SC: Tectonophysics [T]
MN: Fall Meeting 2005