The volcanic equivalent of gabbro, for 10 points, name this mafic rock, the most common igneous extrusive.
One type of this rock forms the earliest stage of the tholeiitic evolutionary trend. Its volatile-rich classifications include nephelinite and calc-alkaline, which contain high kalia to silica ratios. Magma with this composition is derived from the partial melting of peridotite, and its metamorphism produces hornblende schist. It is most commonly generated due to depressurization melting at divergent margins such as mid-ocean ridges, and forms the dominant lithology associated with hot spots. The volcanic equivalent of gabbro, for 10 points, name this mafic rock, the most common igneous extrusive.
One type of this rock forms the earliest stage of the tholeiitic evolutionary trend.
{basalt}