Инд. авторы:	Shatskiy A., Sharygin I.S., Gavryushkin P.N., Litasov K.D., Borzdov Y.M., Shcherbakova A.V., Higo Y., Funakoshi K.-I., Palyanov Y.N., Ohtani E.
Заглавие:	The system K2CO3-MgCO3 at 6 GPa and 900-1450 °c
Библ. ссылка:	Shatskiy A., Sharygin I.S., Gavryushkin P.N., Litasov K.D., Borzdov Y.M., Shcherbakova A.V., Higo Y., Funakoshi K.-I., Palyanov Y.N., Ohtani E. The system K2CO3-MgCO3 at 6 GPa and 900-1450 °c // American Mineralogist. - 2013. - Vol.98. - Iss. 8-9. - P.1593-1603. - ISSN 0003-004X. - EISSN 1945-3027.
Внешние системы:	DOI: 10.2138/am.2013.4407; SCOPUS: 2-s2.0-84882787802; WoS: 000323584000026;
Реферат:	eng: Phase relations in the K2CO3-MgCO3 system have been studied in high-pressure high-temperature (HPHT) multi-anvil experiments using graphite capsules at 6.0 ± 0.5 GPa pressures and 900-1450 °C temperatures. Subsolidus assemblies comprise the fields K 2CO3+K2Mg(CO3)2 and K2Mg(CO3)2+MgCO3 with the transition boundary near 50 mol% MgCO3 in the system. The K2CO 3-K2Mg(CO3)2 eutectic is established at 1200 °C and 25 mol% MgCO3. Melting of K2CO 3 occurs between 1400 and 1450 °C. We propose that K 2Mg(CO3)2 disappears between 1200 and 1300 °C via congruent melting. Magnesite is observed as a subliquidus phase to temperatures in excess of 1300 °C. At 6 GPa, melting of the K 2Mg(CO3)2+MgCO3 assemblage can be initiated either by heating to 1300 °C under 'dry' conditions or by adding a certain amount of water at 900-1000 °C. Thus, the K 2Mg(CO3)2 could control the solidus temperature of the carbonated mantle under 'dry' conditions and cause formation of the K- and Mg-rich carbonatite melts similar to those found as microinclusions in 'fibrous' diamonds. The K2Mg(CO 3)2 compound was studied using in situ X ray coupled with a DIA-type multi-anvil apparatus. At 6.5 GPa and 1000 °C, the structure of K2Mg(CO3)2 was found to be orthorhombic with lattice parameters a = 8.8898(7), b = 7.8673(7), and c = 5.0528(5), V = 353.39(4). No structure change was observed during pressure decrease down to 1 GPa. However, recovered K2Mg(CO3)2 exhibited a trigonal R3m structure previously established at ambient conditions.
Ключевые слова:	upper mantle; potassium; phase transition; melting; high temperature; high pressure; graphite; fluid inclusion; experimental mineralogy; diamond; carbonatite; carbonate group; Upper mantle; Potassium carbonate; Limberlite; K2Mg(CO3)2; High-pressure; Experiment; Diamond; Carbonatite;
Издано:	2013
Физ. характеристика:	с.1593-1603