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called compatible elements. Vanadium and scan-
dium are moderately compatible. Rare-earth pat-
terns are particularly diagnostic of the extent of
garnet involvement in the residual solid or in the
fractionating crystals. Melts in equilibrium with
garnet would be expected to be low in HREE, Y
and Sc. MORB is high in these elements; kimber-
lite is relatively low.
Melt-crystal equilibrium is likely to be much
more
imply. As semi-molten diapirs or melt pack-
ets rise in the mantle, the equilibrium phase
assemblages change. The composition of a melt
depends on its entire previous history, including
shallow crystal fractionation. Melts on the wings
of a magma chamber may represent smaller
degrees of partial melting. Erupted melts are
hybrids of low- and high-degree melts, shallow
and deep melting, and melts from peridotites
and eclogites.
complicated
than
the
above
equations
