Аннотация:Melting relations of the MgO - FeO - SiO2 - CaO system were studied over its polythermal section (MgO)49(FeO)21(CaSiO3) 30-(SiO2) 49(FeO)21(CaSiO3)30at 26GPa. A peritectic reaction of bridgmanite with melt was revealed to form the basic assemblage stishovite SiO2 + periclase-wustite solid solution phases (MgO∙FeO)ss (effect of “stishovite paradox”). Experimental phase relations demonstrate the possibility of ultrabasic-basic fractional evolution of the lower-mantle magma and in situ formation of stishovite. Moreover, origin of ultradeep diamonds and associated phases in melts of the MgO - FeO - SiO2 - CaO - (Mg-Fe-Na-K-carbonate) - carbon system have been examined at 24-26 GPa. A key role of the peritectic reaction of bridgmanite in genesis of basic inclusions in lower-mantle diamonds is verified.
http://www.geokhi.ru/rasempg/Shared%20Documents/2016/%D0%A2%D1%80%D1%83%D0%B4%D1%8B%20%D0%92%D0%95%D0%A1%D0%AD%D0%9C%D0%9F%D0%93-2016.pdf
