Ultrabasic-basic differentiation of mantle magmas and natural diamond-parental melts by evidence of physico-chemical experiments

Experimentally at 7 GPa phase relations in two sections of the system garnet peridotite–eclogite– carbonatite are studied in connection with the problem of physico-chemical conditions of differentiation of the upper mantle ultrabasic-basic magmas and formation of continuous series of peridotite–eclogite rocks as well as the syngenesis of diamond and primary inclusions of peridotitic and eclogitic parageneses. Diagrams of equilibrium and fractional crystallization of the boundary silicate multicomponent system peridotite–eclogite are constructed. As a result, a new effect of “peridotite–eclogite tunnel” is established. The tunnel provides formation of the continuous series of peridotite–eclogite rocks of the Earth’s upper mantle. Also, diagrams of equilibrium and fractional crystallization for the polythermal section peridotite30carbonatite70–eclogite35carbonatite65 are constructed. As a result, a combined action of the effects of peridotite–eclogite tunnel and carbonatization of peridotitic magnesian phases is recognized. The effects provide consecutive formation of the phases of peridotitic and eclogitic parageneses in the natural processes of diamond origin.