 It was caused by a mantle plume activity, which led to the stretching of the crust, the intrusion of magma and thus the melting of the lithosphere.Such a model can explain the eruption of ultramafic melts and thus the generation of komatiites and mafic rocks in Luxi granite-greenstone terrane.The axis of the plume consisted of hot ultramafic material with low viscosity, while the head of the plume brought cooler basaltic material.