Lithospheric thickness Africa

These arguments can be refined. In Appendix B, we calculate the mantle heat flow as a function of lithosphere thickness and show how it depends on the surface heat flow. Pressure and temperature estimates from mantle xenoliths may be combined to determine a best-fit geotherm consistent with heat transport by conduction. Mantle heat flow estimates obtained in this manner are in the following ranges 7-15 mW beneath the Fennoscandian Shield (Kukkonen and Peltonen, 1999), 17-25 mwm for the Kalahari craton. South Africa (Rudnick and Nyblade, 1999), and... 

Fig. 5. Thermal evolution of the lithosphere along a cross-section of Africa through 34°E. Arrow shows the location of the plume relative to the northward-moving African plate since 45 Ma. It should be noted that lithosphere cools as y/t south of plume, as we have placed no restriction on maximum thickness of the continental lithosphere. The long-term effect of the plume heating can be crudely estimated, if we assume that a 40 km equivalent thickness of material that is 200 K hotter than normal mantle, and with specific heat 4 x 106 JK m", ponds beneath a craton every 300 Ma. The mantle heat flow is increased by 3.4 mWm, or 20-25% of typical mantle heat flow from cratonal areas (e.g. Jaupart et al. 1998). (b) Thickness of plume material ponded beneath lithosphere 45 Ma after plume onset.

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