ИСТИНА

Probability of the upper-mantle ultrabasic-basic magmatic evolution is marked by petrochemical trends with smooth clinopyroxenes and garnets conversions from olivine-normative peridotite to silica-normative eclogite compositions (MacGregor, Carter, 1970). Experimental melting relations of the ultrabasic olivine-orthopyroxene-clinopyroxene-garnet system demonstrate invariant peritectic reaction of orthopyroxene with melt and transition to univariant curve olivine+clinopyroxene+garnet+ melt (Litvin et al., 2016). Experimental melting relations in the join forsterite - jadeite over 4.5 GPa have revealed formation of pyropicgarnet (Gasparik, Litvin, 1997). This is promising for deliverance of the Ol+Cpx+Grt+L univariant association from olivine components and transfer from ultrabasic to basic compositions. Experimental study of melting relations of the multicomponent olivine – clinopyroxene – jadeite system using the polythermal sections Ol – Cpx (= Di35Jd75) and Ol80Jd20 – Di65Jd35 at 6 GPa has discovered invariant peritectic reaction of olivine with jadeite components and transition to univariant curve (clinopyroxene ↔ omphacite) + garnet + melt. The peritectic reaction represent the key to ultrabasic-basic evolution of the upper-mantle magmatism and applicable also to evolution of diamond-parental melts-solutions.