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Phase relations and formation of sodium-rich majoritic garnet in the system Mg3Al2Si3O12–Na2MgSi5O12 at 7.0 and 8.5 GPaстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Bobrov A.V., Litvin Yu A., Bindi L., Dymshits A.M.
- Журнал: Contributions to Mineralogy and Petrology
- Том: 156
- Год издания: 2008
- Издательство: Springer Verlag
- Местоположение издательства: Germany
- Первая страница: 243
- Последняя страница: 257
- DOI: 10.1007/s00410-008-0283-3
- Аннотация: The pseudo-binary system Mg3Al2Si3O12–Na2MgSi5O12 modeling the sodium-bearing garnet solid solutions has been studied at 7 and 8.5 GPa and 1500–1950°C. The Na-bearing garnet is a liquidus phase of the system up to 60 mol% Na2MgSi5O12 (NaGrt). At higher content of NaGrt in the system, En (up to ~80 mol%) and then Cs are observed as liquidus phases. Our experiments provided evidence for a stable sodium incorporation in Grt (0.3─0.6 wt% Na2O) and its control by temperature and pressure. The highest sodium contents were obtained in experiments at P = 8.5 GPa. Near the liquidus (T = 1840°C), the equilibrium concentration of Na-component in Grt is ~5 mol% Na2MgSi5O12. With the temperature decrease, Na concentration in Grt increases, and the maximal Na2MgSi5O12 content of ~12 mol% (1.52 wt% Na2O) is gained at the solidus of the system (T = 1760°С). The data obtained show that most of natural diamonds, with inclusions of Na-bearing garnets usually containing <0.4 wt.% Na2O, could be formed from alkaline carbonate-silicate melts at pressures lower than 7 GPa. Only small portion of majoritic garnets with higher sodium concentrations (>1 wt% Na2O) may crystallize at pressures exceeding 8.5 GPa.
- Добавил в систему: Бобров Андрей Викторович