0 describes rocks containing more dark-colored substances and iron than other rocks
During this stage, the mafic minerals grow faster than plagioclase, exhausting the local melt in mafic components.
Small amounts of mafic and opaque minerals occur.
On the basis of our combined data, a more appealing model for the mafic-ultramafic complexes is the emplacement of solitary intrusions.
This is in agreement with return to more mafic detritus and the proposed increased upper continental crust contribution, together at the expense of felsic detritus.
In continental rift settings, the emplacement of such large volumes of felsic melts requires a huge amount of mafic magma derived from uprising asthenosphere.
In particular, the heat for the melting may have been supplied by mafic mantle-derived magmas.
In weakly deformed gneiss, the mafic minerals (biotite, augite and hornblende) occur as irregular clusters, locally separated from plagioclase by coronas of garnet.
The mafic magmas were probably derived from the upper mantle (spinel stability field) by 9 % partial melting.
