Geochemistry International

, Volume 53, Issue 1, pp 9–18 | Cite as

Phase relations in the system (Mg,Ca)3Al2Si3O12-Na2MgSi5O12 at 7.0 and 8.5 GPa and 1400–1900°C

  • A. M. DymshitsEmail author
  • A. V. Bobrov
  • Yu. A. Litvin


The CaO-MgO-Al2O3-SiO2-Na2O multicomponent system was experimentally studied at 7.0 and 8.5 GPa using an anvil-with-hole toroidal high-pressure apparatus to examine two binary joins: pyropegrossular and grossular-Na-majorite. These and literature data were employed to simulate the liquidus surface of the pyrope-grossular-Na-majorite system. The liquidus surface of garnet of predominantly pyrope composition is dominant in the diagram, and the garnet contains much of the Na2MgSi5O12 end member. Melting was observed in this region at temperatures above 1900°C, and the solidus of the system occurs at temperatures below 1550°C. The pyrope-grossular system shows a miscibility gap at 50–65 mol % of the pyrope component and two series of garnet solid solutions. The dominant phase at grossular and Na-majorite mixing is pyroxene, and garnet crystallizes within a fairly narrow field in the grossular-rich region. All garnets synthesized in the systems have elevated Si and Na concentrations and belong to the majorite series, for which a uniform mechanism of isomorphism (Mg, Ca) + Al = Si + Na was proved.


pyrope sodic majorite grossular experiment phase relations mantle 


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  1. 1.
    M. Akaogi and A. Akimoto, “Pyroxene-garnet solid-solution equilibria in the systems Mg4Si4O12-Mg3Al2Si3O12 and Fe4Si4O12-Fe3Al2Si3O12 at high pressures and temperatures,” Phys. Earth. Planet. Inter. 15, 90–106 (1977).CrossRefGoogle Scholar
  2. 2.
    R. J. Angel, T. Gasparik, N. L. Ross, L. W. Finger, C. T. Prewitt, and R. M. Hazen, “A silica-rich sodium pyroxene phase with six-coordinated silicon,” Nature 335, 156–158 (1988).CrossRefGoogle Scholar
  3. 3.
    R. Berman, “Mixing properties of Ca-Mg-Fe-Mn garnets,” Am. Mineral. 75, 328–344 (1990).Google Scholar
  4. 4.
    A. V. Bobrov, Yu. A. Litvin, L. Bindi, and A. M. Dymshits, “Phase relations and formation of sodium-rich majoritic garnet in the system Mg3Al2Si3O12-Na2MgSi5O12 at 7.0 and 8.5 GPa,” Contrib. Mineral. Petrol. 156, 243–257 (2008b)CrossRefGoogle Scholar
  5. 5.
    A. V. Bobrov, H. Kojitani, M. Akaogi, and Yu. A. Litvin, “Phase relations on the diopside-hedenbergite-jadeite join up to 24 GPa and stability of Na-bearing majoritic garnet,” Geochim. Cosmochim. Acta 72, 2392–2408 (2008a)CrossRefGoogle Scholar
  6. 6.
    A. V. Bobrov, A. M. Dymshits, and Yu. A. Litvin, “Conditions of magmatic crystallization of Na-bearing majoritic garnets in the Earth mantle: evidence from experimental and natural data,” Geochem. Int. 47(10), 951–965 (2009).CrossRefGoogle Scholar
  7. 7.
    A. V. Bobrov, A. M. Dymshits, Yu. A. Litvin, and L. Bindi, “The Mg3Al2Si3O12-Na2MgSi5O12 system at pressures of 7.0 and 8.5 GPa and a temperature of 1300–1800°C: phase relationships and crystallization of Na-bearing majoritic garnet,” Mosc. Univ. Geol. Bull. 67(5), 289–297 (2012).CrossRefGoogle Scholar
  8. 8.
    V. G. Butvina, A. V. Bobrov, and Yu. A. Litvin, “The pyrope-grossular-almandine system at 6.5 GPa and 1500–1900°C: an experimental study,” Dokl. Earth Sci. 379A, 709–712(2001).Google Scholar
  9. 9.
    R. M. Davies, W. L. Griffin, S. Y. O’ Reilly, and T. E. McCandless, “Inclusions in diamonds from the K14 and K10 kimberlites, Buffalo Hills, Alberta, Canada: diamond growth in a plume?,” Lithos 77, 99–111 (2004).CrossRefGoogle Scholar
  10. 10.
    A. M. Dymshits, A. V. Bobrov, L. Bindi, Yu. A. Litvin, K. D. Litasov, A. F. Shatskiy, E. Ohtani, “Na-bearing majoritic garnet in the Na2MgSi5O12-Mg3Al2Si3O12 join at 11–20 GPa: phase relations, structural peculiarities and solid solutions,” Geochim. Cosmochim. Acta 105, 1–13 (2013).CrossRefGoogle Scholar
  11. 11.
    T. Gasparik, “Transformation of enstatite-diopside-jadeite pyroxenes to garnet,” Contrib. Mineral. Petrol. 102, 389–405 (1989).CrossRefGoogle Scholar
  12. 12.
    T. Gasparik, “Enstatite-jadeite join and its role in the Earth’s mantle,” Contrib. Mineral. Petrol. 111, 283–298 (1992).CrossRefGoogle Scholar
  13. 13.
    T. Gasparik, “Diopside-jadeite join at 16–22 GPa,” Phys. Chem. Mineral. 23, 476–486 (1996).CrossRefGoogle Scholar
  14. 14.
    T. Gasparik and Yu. A. Litvin, “Stability of Na2Mg2Si2O7 and melting relations in the forsteritejadeite join at pressures up to 22 GPa,” Eur. J. Mineral. 9, 311–326 (1997).CrossRefGoogle Scholar
  15. 15.
    C. A. Geiger, “Thermodynamics of (Fe2+,Mn2+,Mg,Ca)3Al2Si3O12 garnet: a review and analysis,” Mineral. Petrol. 66, 271–299 (1999).CrossRefGoogle Scholar
  16. 16.
    D. L. Hamilton and C. M. B. Henderson, “The preparation of silicate compositions by a gelling method,” Mineral. Mag. 36, 832–838 (1968).CrossRefGoogle Scholar
  17. 17.
    B. Harte and N. Cayzer, “Decompression and unmixing of crystals included in diamonds from the mantle transition zone,” Phys. Chem. Mineral. 34, 647–656 (2007).CrossRefGoogle Scholar
  18. 18.
    T. Irifune, “An experimental investigation of the pyroxene-garnet transformation in a pyrolite composition and its bearing on the constitution of the mantle,” Phys. Earth Planet. Inter. 45, 324–336 (1987).CrossRefGoogle Scholar
  19. 19.
    T. Irifune and E. Ohtani, “Melting of pyrope Mg3Al2Si3O12 up to 10 GPa: possibility of a pressure-induced structural change in pyrope melt,” J. Geophys. Res. 91, 9357–9366 (1986).CrossRefGoogle Scholar
  20. 20.
    Yu. A. Litvin, Physicochemical Studies of Melting of Materials from Deep Earth (Nauka, Moscow 1991) [in Russian].Google Scholar
  21. 21.
    I. Yu. Malinovskii, A. M. Doroshev, and A. A. Kalinin, “Study of the pyrope-grossular garnet join stability at P = 30 Kbar,” (1983).Google Scholar
  22. 22.
    R. O. Moore and J. J. Gurney, “Pyroxene solid solution in garnets included in diamonds,” Nature 318, 553–555 (1985).CrossRefGoogle Scholar
  23. 23.
    S. Ono and A. Yasuda, “Compositional change of majoritic garnet in a MORB composition from 7 to 17 GPa and 1400 to 1600°C,” Phys. Earth. Planet. Inter. 96, 171–179 (1996).CrossRefGoogle Scholar
  24. 24.
    A. E. Ringwood, “Phase transformations and their bearing on the constitution and dynamics of the mantle,” Geochim. Cosmochim. Acta 55, 2083–2110 (1991).CrossRefGoogle Scholar
  25. 25.
    V. S. Shatskii, D. A. Zedgenizov, and A. L. Ragozin, “Majoritic garnets in diamonds from placers of the northeastern Siberian Platform,” 432 (2), 835–838 (2010).Google Scholar
  26. 26.
    N. V. Sobolev, E. S. Efimova, L. F. Reimers, O. D. Zakharchenko, A. I. Makhin, and L. V. Usova, “Mineral inclusions in the garnets from Arkhangelsk kimberlite province,” Geol. Geofiz. 38(2), 358–370 (1997).Google Scholar
  27. 27.
    T. Stachel, “Diamonds from the asthenosphere and the transition zone,” Eur. J. Mineral. 13, 883–892 (2001).CrossRefGoogle Scholar
  28. 28.
    N. V. Surkov and Yu. G. Gartvich, “Experimental study of phase equilibria in the pyrope-grossular join at a pressure of 30 kbar,” Petrology 8(1), 84–95 (2000).Google Scholar
  29. 29.
    V. L. Vinograd and M. H. F. Sluiter, “Thermodynamics of mixing in pyrope-grossular Mg3Al2Si3O12-Ca3Al2Si3O12 solid solution from lattice dynamics calculation and Monte Carlo simulations,” Am. Mineral. 91, 1815–1830 (2006).CrossRefGoogle Scholar
  30. 30.
    W. Wang, S. Sueno, E. Takahashi, H. Yurimoto, and T. Gasparik, “Enrichment processes at the base of the Archean lithospheric mantle: observations from traceelement characteristics of pyropic garnet inclusions in diamond,” Contrib. Mineral. Petrol. 139, 720–733 (2000).CrossRefGoogle Scholar

Copyright information

© Pleiades Publishing, Ltd. 2015

Authors and Affiliations

  • A. M. Dymshits
    • 1
    • 2
    Email author
  • A. V. Bobrov
    • 3
  • Yu. A. Litvin
    • 4
  1. 1.Sobolev Institute of Geology and Mineralogy, Siberian BranchRussian Academy of SciencesNovosibirskRussia
  2. 2.Novosibirsk State UniversityNovosibirskRussia
  3. 3.Geological FacultyMoscow State UniversityLeninskie Gory, MoscowRussia
  4. 4.Institute of Experimental MineralogyRussian Academy of SciencesChernogolovka, Moscow oblastRussia

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