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Revision of the Calcite–Aragonite Transition, with the Location of a Triple Point between Calcite I, Calcite II and Aragonite


CONFLICTING reports have been published for the position of the calcite–aragonite phase transition, and two factors contributing to this are the slow solid state reaction kinetics1 and the problems of quenching the stable assemblage2. Bell and England2 concluded from their experiments that aragonite which formed stably within a wide pressure range (above 600° C) inverted to calcite during the quench. We have recently extended the phase relationships involving a liquid phase in the system calcium oxide–carbon dioxide–water from 4 kbars pressure3,4 to 40 kbars5 using a piston-and-cylinder high-pressure apparatus. The liquids in this system are very reactive media, and no problems have been encountered in reaching equilibrium in this and a variety of related systems6. Across the calcite–aragonite boundary, the ternary phase assemblage calcite + liquid + vapour undergoes a transition to aragonite + liquid + vapour. In runs completed at pressures well above and well below the phase boundary, aragonite and calcite crystals in the quenched assemblage calcium carbonate + liquid + vapour were positively identified by X-ray and optical properties. The morphology of aragonite crystals coexisting with the ternary liquid is distinct from that of the calcite crystals, and the original shape of the equilibrium phase, aragonite or calcite, becomes frozen into the surrounding liquid during the quench and is thus preserved for microscopic examination. The shape of the carbonate crystals in the quenched assemblage calcium carbonate + liquid + vapour was therefore used to bracket the calcite–aragonite transition boundary down to the solidus temperature at 580° C. X-ray powder diffraction and refractive-index measurements demonstrate that crystals with the morphology of aragonite, in runs close to the transition boundary, have inverted to complexly twinned, biaxial calcite with optic axial angles ranging from near zero up to an estimated 20° (2V for aragonite is 18°). The implications of this observation have been discussed elsewhere7.

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  1. Davis, B. L., and Adams, L. H., J. Geophys. Res., 70, 433 (1965).

    Article  ADS  CAS  Google Scholar 

  2. Bell, P. M., and England, J. L., Ann. Rep. of the Director of the Geophys. Lab., Carnegie Institution, Washington, D.C., 63, 176 (1964).

    Google Scholar 

  3. Wyllie, P. J., and Tuttle, O. F., J. Petrol., 1, 1 (1960).

    Article  ADS  CAS  Google Scholar 

  4. Wyllie, P. J., and Raynor, E. J., Amer. Min., 50, 2077 (1965).

    CAS  Google Scholar 

  5. Boettcher, A. L., and Wyllie, P. J., Trans. Amer. Geophys. Union (in the press) (1967).

  6. Wyllie, P. J., in The Carbonatites, edit. by Tuttle, O. F., and Gittins, J. (Wiley-Interscience, 1967).

    Google Scholar 

  7. Boettcher, A. L., and Wyllie, P. J., Amer. Min. (in the press) (1967).

  8. Boeke, H. E., Neues Jahrb. Min. U. Geol., 1, 91 (1912).

    Google Scholar 

  9. Bridgman, P. W., Amer. J. Sci., 237, 7 (1939).

    Article  ADS  CAS  Google Scholar 

  10. Crawford, W. A., and Fyfe, W. S., Science, 144, 1569 (1964).

    Article  ADS  CAS  Google Scholar 

  11. Jamieson, J. C., J. Geol., 65, 334 (1957).

    Article  ADS  CAS  Google Scholar 

  12. Brown, W. H., Fyfe, W. S., and Turner, F. J., J. Petrol., 3, 566 (1962).

    Article  ADS  CAS  Google Scholar 

  13. Coleman, R. G., and Lee, D. E., Amer. J. Sci., 260, 577 (1962).

    Article  ADS  CAS  Google Scholar 

  14. McKee, B., Amer. Min., 47, 379 (1962).

    CAS  Google Scholar 

  15. Vance, J. A. (personal communication).

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BOETTCHER, A., WYLLIE, P. Revision of the Calcite–Aragonite Transition, with the Location of a Triple Point between Calcite I, Calcite II and Aragonite. Nature 213, 792–793 (1967).

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