Abstract
The univariant pressure temperature curve of the reaction aluminous enstatite solid solution+sillimanite⇌sapphirine solid solution+quartz was determined experimentally in the pressure range between 12 and 20 kb. It is defined by four reversals at 15 kb, 1140°+10°C; at 1190°C, 15.9±1 kb; at 1300°C, 17.2±1 kb; and at 1400°C, 18±1 kb. Among the coexisting phases the Al-content of the enstatites increases strongly, with rising temperatures and pressures, up to values approaching that of pyrope composition, whereas the Al-content of the sapphirine solid solution appears to increase only slightly. Concomitantly, the sillimanites, most probably of invariant composition, exhibit growing Al/Si-disorder. These compositional and structural variations, in addition to the changing stoichiometry of the reaction equation, cause the progressively decreasing positive dP/dT slope of the equilibrium curve. — The assemblage sapphirine + quartz found in natural granulites is indicative of conditions of water pressure much lower than total pressure.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Ackermand, D.: Stabilität und Synthese des Sapphirins im System MgO-Al2O3-SiO2 (H2O). Diss. University of Bochum, 96 p. (1970).
Barker, F.: Sapphirine-bearing rock, Val Codera, Italy. Am. Mineralogist 146–152 (1964).
Beger, R. M., Burnham, C. W, Hays, J. F.: Structural changes in sillimanite at high temperature (Abstract). Geol. Soc. Am. Ann. Meeting, 490–491 (1970).
Boyd, F. R., England, J. L.: Pyrope. Carnegie Inst. Washington Year Book 58, 83–87 (1959).
Boyd, F. R., England, J. L.: Apparatus for phase-equilibrium measurements at pressures up to 50 kilobars and temperatures up to 1750° C. J. Geophys. Res. 65, 741–748 (1960).
Boyd, F. R., England, J. L.: The system enstatite-pyrope. Carnegie Inst. Washington Year Book 63, 157–161 (1964).
Burnham, C. W.: Lattice constant refinement. Carnegie Inst. Washington Year Book 61, 132–135 (1962).
Chatterjee, N. D., Schreyer, W.: Stabilitätsbeziehungen der Paragenese Sapphirin+Quarz (Abstract). Fortschr. Mineral. 47, Beiheft 1, 9–10 (1970).
Chinner, G. A., Sweatman, T. R.: A former association of enstatite and kyanite. Mineral. Mag. 36, 1052–1060 (1968).
Dallwitz, W. B.: Co-existing sapphirine and quartz in granulite from Enderby Land, Antarctica. Nature 219, 476–477 (1968).
Durović, S.: A statistical model for the crystalline structure of mullite. Soviet Phys. Cryst. 7, 271–278 (1962).
Greenwood, H. J.: The synthesis and stability of anthophyllite. J. Petrol. 4, 317–351 (1963).
Hensen, B. J., Essene, E. J.: Stability of pyrope-quartz in the system MgO-Al2O2-SiO2. Contr. Mineral. and Petrol. 30, 72–83 (1971).
Hensen, B. J., Green, D. H.: Experimental data on coexisting cordierite and garnet under high grade metamorphic conditions. Phys. Earth Planet. Interiors 3, 431–440 (1970).
Heydemann, P. L. M.: The Bi I–II transition pressure measured with a dead-weight piston gauge. J. Appl. Phys. 38, 2640–2644 (1967).
Johannes, W., Bell, P. M., Mao, H. K., Boettcher, A. L., Chipman, D. W., Hays, J. F., Newton, R. C., Seifert, F.: An interlaboratory comparison of piston-cylinder pressure calibration using the albite-breakdown reaction. Contr. Mineral. and Petrol. 32, 24–38 (1971).
Moore, J. M., Leong, K. M.: Comments on “sapphirine reactions in deep-seated granulites near Wilson Lake, Central Labrador, Canada” by S. A. Morse and J. H. Talley. Earth Planet. Sci. Letters 12, 355–356 (1971).
Morse, S. A.: Reply to Comments by J. M. Moore and K. M. Leong. Earth Planet. Sci. Letters 12, 357 (1971).
Morse, S. A., Talley, J. H.: Sapphirine reactions in deep-seated granulites near Wilson Lake, Central Labrador, Canada. Earth Planet. Sci. Letters 10, 325–328 (1971).
Newton, R. C.: An experimental determination of the high pressure stability limits of magnesian cordierite under wet and dry conditions. J. Geol. (in Press) (1972).
Richardson, S. W., Bell, P. M., Gilbert, M. C.: Kyanite-sillimanite equilibrium between 700° and 1500°C. Am. J. Sci. 266, 513–541 (1968).
Sadanaga, R., Tokonami, M., Takéuchi, Y.: The structure of mullite, 2Al2O3·SiO2, and relationships with structures of sillimanite and andalusite. Acta Cryst. 15, 65–68 (1962).
Schreyer, W., Seifert, F.: Compatibility relations of the aluminium silicates in the system MgO-Al2O3-SiO2-H2O at high pressures. Am. J. Sci. 267, 371–388 (1969a).
Schreyer, W., Seifert, F.: High-pressure phases in the system MgO-Al2O3-SiO2-H2O. Am. J. Sci. 267 A, 407–443 (1969b).
Schreyer, W., Seifert, F.: Pressure dependence of crystal structures in the system MgOAl2O3-SiO2-H2O at pressures up to 30 kilobars. Phys. Earth Planet. Interiors 3, 422–430 (1970).
Schreyer, W., Yoder, H. S.: Instability of anhydrous Mg-cordierite at high pressures. Carnegie Inst. Washington Year Book 59, 90–91 (1960).
Schreyer, W., Yoder, H. S.: The system Mg-cordierite-H2O and related rocks. Neues Jahrb. Mineral., Abhandl. 101, 271–342 (1964).
Seifert, S.: Stabilität und Kompatibilität von Sapphirin im Bereich 1–7 kb Wasserdruck (Abstract). Fortschr. Mineral. 49, Beiheft 1, 52–53 (1971).
Skinner, B. J., Boyd, F. R.: Aluminous enstatites. Carnegie Inst. Washington Year Book 63, 163–165 (1964).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Chatterjee, N.D., Schreyer, W. The reaction enstatitess+sillimanite ⇌ sapphiriness+quartz in the system MgO-Al2O3-SiO2 . Contr. Mineral. and Petrol. 36, 49–62 (1972). https://doi.org/10.1007/BF00372834
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00372834