Инд. авторы:	Shatskiy A, Podborodnikov I.V., Arefiev A.V., Bekhtenova A.E, Vinogradova Y.G., Stepanov K.M., Litasov K.D.
Заглавие:	Pyroxene-carbonate reactions in the CaMgSi2O6 +/- NaAlSi2O6 + MgCO3 +/- Na2CO3 +/- K2CO3 system at 3-6 GPa: Implications for partial melting of carbonated peridotite
Библ. ссылка:	Shatskiy A, Podborodnikov I.V., Arefiev A.V., Bekhtenova A.E, Vinogradova Y.G., Stepanov K.M., Litasov K.D. Pyroxene-carbonate reactions in the CaMgSi2O6 +/- NaAlSi2O6 + MgCO3 +/- Na2CO3 +/- K2CO3 system at 3-6 GPa: Implications for partial melting of carbonated peridotite // Contributions to Mineralogy and Petrology. - 2021. - Vol.176. - Iss. 5. - Art.34. - ISSN 0010-7999. - EISSN 1432-0967.
Внешние системы:	DOI: 10.1007/s00410-021-01790-9; WoS: 000640485200001;
Реферат:	eng: The reactions between pyroxenes and carbonates have been studied in the CaMgSi2O6 + MgCO3 (Di + 2Mgs), CaMgSi2O6 + NaAlSi2O6 + 2MgCO(3) (Di + Jd + 2Mgs), CaMgSi2O6 + Na2Mg(CO3)(2) (Di + Eit), and CaMgSi2O6 + K2Mg(CO3)(2) (Di + K2Mg) systems at pressures of 3.0 and 4.5 GPa in the temperature range 850-1300 degrees C and compared with those established previously at 6.0 GPa. The Di + 2Mgs solidus locates at 1220 degrees C / 3 GPa and 1400 degrees C / 6 GPa. Near-solidus melt is carbonatitic with SiO2 < 4 wt% and Ca# 56. The Di + Jd + 2Mgs solidus locates near 1050 degrees C at 3 GPa, rises to 1200 degrees C at 4.5 GPa, and 1350 degrees C at 6 GPa. The solidus is controlled by the reaction: 4NaAlSi(2)O(6)center dot 2CaMgSi(2)O(6) (clinopyroxene) + 12MgCO(3) (magnesite) = 2MgAl(2)SiO(6)center dot 5Mg(2)Si(2)O(6) (clinopyroxene) + 2[Na2CO3 center dot CaCO3 center dot MgCO3] (liquid) + 6CO(2). As pressure increases, the composition of solidus melt evolves from 26Na(2)CO(3)center dot 74Ca(0.58)Mg(0.42)CO(3) at 3 GPa to 10Na(2)CO(3)center dot 90Ca(0.50)Mg(0.50)CO(3) at 6 GPa. Melting in the Di + Eit and Di + K2Mg systems is controlled by the reactions: CaMgSi2O6 (clinopyroxene) + 2(Na or K)(2) Mg(CO3)(2) (eitelite) = Mg2Si2O6 (orthopyroxene) + 2[(Na or K)(2)CO3 center dot Ca0.5Mg0.5CO3] (liquid). The Di + Eit solidus locates at 925 degrees C / 3 GPa and 1100 degrees C / 6 GPa, whereas the Di + K2Mg solidus is located at 50 degrees C lower. The resulting melts have alkali-rich carbonate compositions, (Na or K)(2)CO3 center dot Ca0.4Mg0.6CO3. The obtained results suggest that most carbonates belong to the ultramafic suite would survive during subduction into the deep mantle and experience partial melting involving alkaline carbonates, eitelite or K2Mg(CO3)(2), under geothermal conditions of the subcontinental lithospheric mantle (35-40 mW/m(2)). On the other hand, the jadeite component in clinopyroxene would be an important fluxing agent responsible for the partial melting of carbonated rocks under the rift margin geotherm (60 mW/m(2)) at a depth of about 100 km, yielding the formation of Na-carbonatite melt.
Ключевые слова:	High-pressure experiment; Carbonatite melt; s mantle; Carbonate; Clinopyroxene; Alkalis; Earth’;
Издано:	2021
Физ. характеристика:	34