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(d)
(e)
(f)
(g)
(h)
(i)
Figure 8.18.
Spherical three-dimensional convection models of the mantle (the
uppermost 200-km boundary layer is not shown). Superadiabatic temperatures: red,
hot; blue, cold. (a) Incompressible mantle, constant viscosity, internal heating only,
Ra
= 4 × 10
7
. (b) As (a) but the viscosity of the lower mantle is thirty times the
viscosity of the upper mantle. (c) As (b) showing the isosurface. (d) As (b) showing
the planform. (e) Compressible mantle, constant viscosity,
Ra
= 10
8
. (f) As (e) but
with 38% of heating from the core. (g) As (e) but with an endothermic phase change
of −4 MPa K
−1
at 670 km depth. (h) As (e) but with the viscosity of the lower mantle
thirty times the viscosity of the upper mantle. (i) As (h) and with 38% of heating from
the core. Colour version Plate 14. (Bunge, personal communication 2003 after Bunge
et al
.(1996, 1997).)
