Geoscience Reference
In-Depth Information
Table 12.3
Radius r and density
of different planets in the
inner Solar System.
ρ
Venus
Earth
Moon
Mars
Vesta
r
(km)
6052
6371
1737
3390
520
ρ
(g cm
−
3
)
5.24
5.52
3.34
3.93
3.16
in
Table 12.3
.
Let us consider a basaltic magma formed in the shallow mantle of these
planets and assume a constant mantle density.
a. If the cross-over between plagioclase and clinopyroxene (i.e. the pressure at which
the order of saturation is reversed) is at 0.5 GPa, at which depth will this cross-over
be located? Discuss the implications in terms of the evolution of a molten planet.
b. In the terrestrial mantle, garnet is stable at pressures in excess of 2 GPa. What is the
equivalent depth for the other planets? Discuss the presence of garnet in the mantle
of each planet.
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