HR: 17:30h
AN: T14B-07 INVITED     [Abstracts]
TI: Towards a dynamical link between the formation of mantle plumes and the longevity and composition of hotspot volcanism
AU: * Jellinek, M
EM: markj@physics.utoronto.ca
AF: University of Toronto, Department of Physics 60 Saint George Street, Toronto, ON M5S1A7 Canada
AU: Manga, M
EM: manga@seismo.berkeley.edu
AF: University of California, Dept Earth and Planetary Science, Berkeley, CA 94720-4767
AB: On Earth, a physical link has been proposed between hotspots, regions with particularly persistent, localized, and high rates of volcanism, and underlying deep mantle plumes. This plume model has provided a way to interpret observable phenomena including the volcanological, petrological and geochemical evolution of ocean island volcanoes, the relative motion of plates, continental breakup, global heat flow and the Earth's magnetic field within the broader framework of the thermal history of our planet. Despite the plume model's utility, the underlying dynamics giving rise to hotspots as long-lived stable features have remained elusive. To address the mantle dynamics underlying such hotspots we first use a synthesis of seismological, geodynamic, geomagnetic and geochemical constraints to argue that the source regions for most proposed deep mantle plumes contain dense, low viscosity material at the base of D$^{\prime \prime}$ composed of partial melt, outer core material or a mixture of both. Next, using results from laboratory experiments on thermochemical convection combined with theoretical scaling analyses, we argue that the longevity of mantle plumes in the Earth is a consequence of the interactions between core cooling and this dense layer. Our analysis explains the longevity of hotspots and mantle plumes in the Earth and leads to self-consistent scalings for the topography on the dense layer and the composition of ocean island basalts that are consistent with seismological and geochemical observations.
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 8124 Earth's interior--composition and state (old 8105)
DE: 8125 Evolution of the Earth
DE: 8130 Heat generation and transport
DE: 8147 Planetary interiors (5430, 5724)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting