SYNTHESIS OF OMPHACITES AND ISOMORPHIC FEATURES OF CLINOPYROXENES IN THE SYSTEM CAMGSI2O6-NAALSI2O 6-KALSI2O6
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dc.contributor.author | Safonov O.G. | |
dc.contributor.author | Litvin Yu.A. | |
dc.contributor.author | Perchuk L.L. | |
dc.date.accessioned | 2022-11-03T10:21:03Z | |
dc.date.available | 2022-11-03T10:21:03Z | |
dc.date.issued | 2004 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=13460526 | |
dc.identifier.citation | Petrology, 2004, 12, 1, 70-81 | |
dc.identifier.issn | 0869-5911 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/39332 | |
dc.description.abstract | Omphacites with varying Na/K ratio were synthesized in the system CaMgSi2O6-NaAlSi2O6-KAlSi 2O6 at pressures of 5, 6, and 7 GPa within the temperature interval 1000-1300°C. It was found that both K and Na contents of omphacites increase irregularly with pressure, and there is a distinct negative correlation between K and Na in clinopyroxene at each pressure. The K content of omphacite increases more intensely within a pressure interval of 6-7 GPa. The isomorphism NaM2 ⇄ KM2 is predominant, whereas the substitution [CaM2MgM1] ⇄ [K M2AlM1] increases with decreasing Jadeite content. At the P-T parameters studied, potassium-bearing omphacites coexist with melt containing 15-21 wt % K2O, 54-63 wt % SiO2, and 19-22 wt % Al2O3 at low Na2O concentration independent of the initial Na2O content in starting mixtures. The partition coefficients Kp(K2O) = K2O (in KCpx)/K 2O (in melt) and Kp(Na2O) = Na2O (in KCpx)/Na2O (in melt) increase with pressure, and K p(Na2O) increases more significantly by comparison to Kp(K2O). Thus, omphacite crystallization promotes melt enrichment in potassium. As a result, ultrapotassic mantle melts could be generated. This is exemplified by potassium-bearing omphacite inclusions in diamonds from kimberlite and lamproite pipes. | |
dc.subject | Omphacites | |
dc.title | SYNTHESIS OF OMPHACITES AND ISOMORPHIC FEATURES OF CLINOPYROXENES IN THE SYSTEM CAMGSI2O6-NAALSI2O 6-KALSI2O6 | |
dc.type | Статья |
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