Инд. авторы:	Sharygin I.S., Shatskiy A., Litasov K.D., Golovin A.V., Ohtani E., Pokhilenko N.P.
Заглавие:	Interaction of peridotite with Ca-rich carbonatite melt at 3.1 and 6.5 GPa: Implication for merwinite formation in upper mantle, and for the metasomatic origin of sublithospheric diamonds with Ca-rich suite of inclusions
Библ. ссылка:	Sharygin I.S., Shatskiy A., Litasov K.D., Golovin A.V., Ohtani E., Pokhilenko N.P. Interaction of peridotite with Ca-rich carbonatite melt at 3.1 and 6.5 GPa: Implication for merwinite formation in upper mantle, and for the metasomatic origin of sublithospheric diamonds with Ca-rich suite of inclusions // Contributions to Mineralogy and Petrology. - 2018. - Vol.173. - Iss. 3. - Art.22. - ISSN 0010-7999. - EISSN 1432-0967.
Идентиф-ры:	DOI: 10.1007/s00410-017-1432-3; WoS: 000427307200008;
Реферат:	eng: We performed an experimental study, designed to reproduce the formation of an unusual merwinite + olivine-bearing mantle assemblage recently described as a part of a Ca-rich suite of inclusions in sublithospheric diamonds, through the interaction of peridotite with an alkali-rich Ca-carbonatite melt, derived from deeply subducted oceanic crust. In the first set of experiments, we studied the reaction between powdered Mg-silicates, olivine and orthopyroxene, and a model Ca-carbonate melt (molar Na:K:Ca = 1:1:2), in a homogeneous mixture, at 3.1 and 6.5 GPa. In these equilibration experiments, we observed the formation of a merwinite + olivine-bearing assemblage at 3.1 GPa and 1200 degrees C and at 6.5 GPa and 1300-1400 degrees C. The melts coexisting with this assemblage have a low Si and high Ca content (Ca# = molar 100 x Ca/(Ca + Mg) > 0.57). In the second set of experiments, we investigated reaction rims produced by interaction of the same Ca-carbonate melt (molar Na:K:Ca = 1:1:2) with Mg-silicate, olivine and orthopyroxene, single crystals at 3.1 GPa and 1300 degrees C and at 6.5 GPa and 1400 degrees C. The interaction of the Ca-carbonate melt with olivine leads to merwinite formation through the expected reaction: 2Mg(2)SiO(4) (olivine) + 6CaCO(3) (liquid) = Ca3MgSi2O8 (merwinite) + 3CaMg(CO3)(2) (liquid). Thus, our experiments confirm the idea that merwinite in the upper mantle may originate via interaction of peridotite with Ca-rich carbonatite melt, and that diamonds hosting merwinite may have a metasomatic origin. It is remarkable that the interaction of the Ca-carbonate melt with orthopyroxene crystals does not produce merwinite both at 3.1 and 6.5 GPa. This indicates that olivine grain boundaries are preferable for merwinite formation in the upper mantle.
Ключевые слова:	ECLOGITE; TRANSPORT; HIGH-PRESSURE; TRANSITION ZONE; EARTHS INTERIOR; PHASE-RELATIONS; DEEP MANTLE; UDACHNAYA-EAST KIMBERLITE; CONTINENTAL LITHOSPHERIC MANTLE; Carbonatite melt; Subduction; Mantle; Merwinite; Diamond; EXTRACTION;
Издано:	2018
Физ. хар-ка:	22