An experimental determination of primary carbonatite magma composition (original) (raw)

Nature volume 335, pages 343–346 (1988) Cite this article

Abstract

Carbonatites are uncommon carbonate-rich rocks usually found in continental intra-plate regions and often associated with rifting. There has been much debate as to whether carbonatite magmas are primary melts derived from partial melting of mantle peridotite, or are formed by exsolution of an immiscible carbonate melt fraction from phonolitic or nephelinitic magmas. Our experiments on the phase relationships of carbonate and amphibole-bearing peridotite (containing 0.3% H2O and 0.5–2.5% CO2) show that sodic dolomitic carbonatite magma coexists with an amphibole lherzolite assemblage in a field ranging from 21 to 30 kbar and 930 to 1,080 °C, spanning a pressure and temperature interval between the solidus and the amphibole breakdown and melting curve. Thus primary carbonatite melts may occur under suitable geothermal conditions. The nature of the peridotite solidus and of the melting reactions differ considerably from published models1–3. The carbonatite melt composition, determined by a series of 'sandwich' experiments, was found to be rich in Na, Mg, Ca and Fe, with a small dissolved silicate content. This melt quenches to an assemblage of dolomite and Na–Mg carbonate minerals, producing textures similar to those preserved in samples from Oldoinyo Lengai4, Homa mountains, Tanzania5 and Kaiserstuhl, Germany6.

This is a preview of subscription content, access via your institution

Access options

Subscribe to this journal

Receive 52 print issues and online access

$199.00 per year

only $3.83 per issue

Buy this article

USD 39.95

Prices may be subject to local taxes which are calculated during checkout

Additional access options:

Similar content being viewed by others

References

  1. Olafsson, M. & Eggler, D. H. Earth planet. Sci. Lett. 64, 205–315 (1983).
    Article Google Scholar
  2. Wyllie, P. J. Earth planet. Sci. Lett. 82, 391–397 (1987).
    Article ADS CAS Google Scholar
  3. Eggler, D. H. Earth planet. Sci. Lett. 82, 398–400 (1987).
    Article ADS CAS Google Scholar
  4. Dawson, J. B., Garson, M. S. & Roberts, B. Geology 15, 765–768 (1987).
    Article ADS CAS Google Scholar
  5. Deans, T. & Roberts, B. J. geol. Soc. Lond. 141, 563–580 (1984).
    Article CAS Google Scholar
  6. Keller, J. J. Volcan. geolherm. Res. 9, 423–431 (1981).
    Article ADS CAS Google Scholar
  7. LeBas, M. J. Miner. Mag. 44, 133–140 (1981).
    Article CAS Google Scholar
  8. McKie, D. & Frankis, E. J. Z. Kristallogr. 145, 73–95 (1977).
    Article CAS Google Scholar
  9. Hay, R. L. Geology 11, 599–602 (1983).
    Article ADS CAS Google Scholar
  10. Deines, P. & Gold, D. P. Geochim. cosmochim. Acta 37, 1709–1733 (1973).
    Article ADS CAS Google Scholar
  11. Sheppard, S. M. F. & Dawson, J. B. Phys. Chem. Earth 9, 747–763 (1975).
    Article CAS Google Scholar
  12. Nelson, D. R., Chivas, A. R., Chappell, B. W. & McCulloch, M. T. Geochim. cosmochim. Acta 52, 1–17 (1988).
    Article ADS CAS Google Scholar
  13. Lancelot, J. R. & Allegre, C. J. Earth planet. Sci. Lett. 22, 233–238 (1974).
    Article ADS CAS Google Scholar
  14. Koster Van Groos, A. F. Am. J. Sci. 275, 163–185 (1975).
    Article ADS CAS Google Scholar
  15. Donaldson, C. H. & Dawson, J. B. Contr. Miner. Petrol. 67, 139–149 (1978).
    Article ADS CAS Google Scholar
  16. Freestone, I. C. & Hamilton, D. L. Contr. Miner. Petrol. 73, 105–117 (1980).
    Article ADS CAS Google Scholar
  17. Twyman, J. D. & Gittins, J. in Alkaline Igneous Rocks (eds Fitton, J. G. & Upton, B. G. J.) 85–94 (Blackwell, Oxford, 1987).
    Google Scholar
  18. Le Bas, M. J. in Alkaline Igneous Rocks (eds Fitton, J. G. & Upton, B. G. J.) 53–83 (Blackwell, Oxford, 1987).
    Google Scholar
  19. Koster van Groos, A. T. & Wyllie, P. J. Am. J. Sci. 26, 932–967 (1968).
    Article ADS Google Scholar
  20. Wyllie, P. J. & Tuttle, O. F. J. Petrology 1, 1–46 (1960).
    Article ADS CAS Google Scholar
  21. Wyllie, P. J. & Huang, W. L. Contr. Miner. Petrol. 54, 79–107 (1976).
    Article ADS CAS Google Scholar
  22. Wyllie, P. J. in Magmatic Processes: Physicochemical Principles (ed. Mysen, B. O.) 107–119 (Geochem. Soc. spec. Publ. 1, 1987).
    Google Scholar
  23. Eggler, D. H. Australian Journal of Earth Sciences spec. Publ. 14, IV International Kimberlite Conference (1988).
  24. Eggler, D. H. Am. J. Sci. 278, 305–343 (1978).
    Article ADS CAS Google Scholar
  25. Brey, G. & Green, D. H. Contr. Miner. Petrol. 55, 217–230 (1976).
    Article ADS CAS Google Scholar
  26. Brey, G., Brice, W. R., Ellis, D. J., Green, D. H., Harris, K. L. & Ryabchikov, I. D. Earth planet. Sci. Lett. 62, 63–74 (1983).
    Article ADS CAS Google Scholar
  27. Green, D. H. Earth planet. Sci. Lett. 19, 37–55 (1973).
    Article ADS CAS Google Scholar
  28. Eggler, D. H. & Baker, D. R. in Advances in Earth and Planetary Sciences: High Pressure Research in Geophysics 12 (eds Akimoto, S. & Manghnani, M. H.) 237–250 (Reidel, Dordrecht, 1982).
    Book Google Scholar
  29. Holloway, J. R. Geochim. cosmochim. Acta 37, 651–666 (1973).
    Article ADS CAS Google Scholar
  30. Green, D. H. Earth planet. Sci. Lett. 17, 456–465 (1973).
    Article ADS CAS Google Scholar
  31. Green, D. H. et al. Proc. Pacif. Rim Congr. A.I.M.M. Victoria 621–632 (1987).
  32. Hamilton, D. L., Freestone, I. C., Dawson, J. B. & Donaldson, C. H. Nature 279, 52–54 (1979).
    Article ADS CAS Google Scholar
  33. Wendlandt, R. F. & Harrison, W. J. Contr. Miner. Petrol. 69, 409–419 (1979).
    Article ADS CAS Google Scholar
  34. Taylor, W. R. & Green, D. H. Nature 332, 349–352 (1988).
    Article ADS CAS Google Scholar
  35. Green, D. H., Falloon, T. J. & Taylor, W. R. in Magmatic Processes: Physicochemical Principles (ed. Mysen, B. O.) 139–154 (The Geochemical Society, 1987).
    Google Scholar

Download references

Author information

Authors and Affiliations

  1. Geology Department, University of Tasmania, GPO Box 252C, Hobart, Australia, 7001
    Margaret E. Wallace & David H. Green

Authors

  1. Margaret E. Wallace
  2. David H. Green

Rights and permissions

About this article

Cite this article

Wallace, M., Green, D. An experimental determination of primary carbonatite magma composition.Nature 335, 343–346 (1988). https://doi.org/10.1038/335343a0

Download citation

This article is cited by