HR: 0800h
AN: V51B-0525    [Abstracts]
TI: THE CHEMICAL SURFACE SIGNATURE CREATED BY UPWELLING PLUMES
AU: * Schmalzl, J
EM: joergs@uni-muenster.de
AF: University Muenster Institute of Geophysics, Corrensstr. 24, Muenster, NRW 48149 Germany
AU: Hansen, U
EM: hansen@earth.uni-muenster.de
AF: University Muenster Institute of Geophysics, Corrensstr. 24, Muenster, NRW 48149 Germany
AB: Convective flows govern much of the dynamics of the Earth. Examples of such flows are convection in the Earth's mantle, convection in magma chambers and much of the dynamics of the world oceans. Nowadays these time-dependent flows are often studied by means of three dimensional (3D) numerical models which solve the equations for the transport of heat and momentum alternatingly. These flows are often driven by a temperature difference. But for many flows there is also an active or passive chemical component that has to be considered such as entrainment of material from an underlying layer. One characteristics of these flows is that the chemical diffusivity is very small. Implementing such a chemical field with a very low diffusivity into a numerical model using a field approach is difficult due to numerical diffusion introduced by the Eulerian schemes. We have implemented a tracer-mesh method which tracks only the position of the interface between the two different components. While the thermal shape of a plume for conditions as appropriate for the Earth's mantle is cylindrical in an first order approximation the shape of the entrained chemical material also has a very strong sheet-like component. This can be important for the understanding of the observed isotopic variability of plumes.
UR: http://earth.uni-muenster.de/$\sim$joergs
DE: 8450 Planetary volcanism (5480)
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 7207 Core and mantle
DE: 3640 Igneous petrology
DE: 1025 Composition of the mantle
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting