HR: 10:55h
AN: V42B-03    [Abstracts]
TI: Structure of the Mantle Transition Zone Beneath Kenya, East Africa
AU: Nyblade, A A
EM: andy@geosc.psu.edu
AF: The Pennsylvania State University, Department of Geosciences, University Park, PA 16802, United States
AU: * Huerta, A D
EM: ahuerta@geosc.psu.edu
AF: The Pennsylvania State University, Department of Geosciences, University Park, PA 16802, United States
AB: The relationship between the surface expression of magmatism and extension with the deeper mantle processes remains enigmatic. While Cenozoic volcanism, plateau uplift, and rifting in the Kenya Rift of eastern Africa must be associated with a mantle thermal anomaly, the exact nature of the anomaly is highly speculative. Previous studies of the mantle structure beneath Tanzania suggest that the region is underlain by a plume head, but that the plume stem may be located further to the north in Kenya. To further define the thermal structure of the mantle beneath the Kenya Rift we analyze teleseismic P-waves and PP-waves from a temporary PASSCAL Kenya Broadband Seismic Experiment, permanent stations in Kenya and Tanzania , and re-processed teleseismic P-waves and PP-waves from the Tanzania Broadband Seismic Experiment. The resulting coverage is densest in south-central Kenya and northern Tanzania. Results from stacking the receiver functions with a 1D velocity model reveals depressions in of the 410 km discontinuity, suggesting thermally perturbed mantle structure. However, the depth to the 660 km discontinuity is slightly elevated throughout much of the study area, inconsistent with the presence of a mantle tail. The calculated thickness of the mantle transition zone (MTZ) in southern Kenya shows no systematic trend. In Tanzania, the MTZ is somewhat thinned in the north-central area and thickened in the west-central area, consistent with previous receiver function analysis in Tanzania.
DE: 7208 Mantle (1212, 1213, 8124)
DE: 8121 Dynamics: convection currents, and mantle plumes
DE: 8137 Hotspots, large igneous provinces, and flood basalt volcanism
DE: 9305 Africa
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting