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An experimental study of the effect of Ca upon garnet-clinopyroxene Fe-Mg exchange equilibria

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Abstract

A series of basaltic compositions and compositions within the simple system CaO-MgO-FeO-Al2O3-SiO2 have been crystallized to garnetclinopyroxene bearing mineral assemblages in the range 24–30 kb pressure, 750°–1,300° C temperature. Microprobe analyses of coexisting garnet and clinopyroxene show that K D(Fe2+/MgG+/Fe2+/MgCpx) for the Fe-Mg exchange reaction between coexisting garnet and clinopyroxene is obviously dependent upon the Ca-content and apparently independent of the Mg/(Mg+Fe) content of the clinopyroxene and garnet. The Ca-effect is believed to be due to a combination of non-ideal Ca-Mg substitutions in the garnet and clinopyroxene.

Our data and interpretation reconciles previous inconsistencies in the temperature dependence of K D − values determined in experimental studies of simple systems, complex basalt, grospydite and garnet peridotite compositions. Previous differences between the effect of pressure upon K Das predicted from simple system theory (Banno, 1970), and that observed in experiments on multicomponent natural rock compositions (Råheim and Green, 1974a) can now be resolved.

We have determined K Das a function of P, T, and X CaGt (grossular) and derived the empirical relation

$$T\left( {^\circ {\text{K}}} \right) = \frac{{3104X_{{\text{Ca}}}^{{\text{Gt}}} + 3030 + 10.86P\left( {{\text{kb}}} \right)}}{{\ln K_{\text{D}} + 1.9034}}$$

.

This empirical relationship has been applied to garnet-clinopyroxene bearing rocks from a wide range of geological environments. The geothermometer yields similar estimates for garnet-clinopyroxene equilibration for neighbouring rocks of different composition and different K Dvalues. In addition, temperature estimates using the above relationship are more consistent with independent temperature estimates based on other geothermometers than previous estimates which did not correct for the Ca-effect.

An alternative approach to the above empirical geothermometer was attempted using regular solution models to derive Margules parameters for various solid solutions in garnets and clinopyroxenes. The derived Margules parameters are broadly consistent with those determined from binary solution studies, but caution must be exercised in interpreting them in terms of actual thermodynamic properties of the relevant crystalline solid solutions because of the assumptions which necessarily have to be made in this approach.

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References

  • Akella, J.: Garnet-pyroxene equilibria in the system CaSiO3-MgSiO3-Al2O3 and in a natural mineral mixture. Am. Mineral. 61, 589–598 (1976)

    Google Scholar 

  • Banno, S.: Classification of eclogites in terms of their physical conditions of origin. Phys. Earth Planet. Inter. 3, 405–421 (1970)

    Google Scholar 

  • Coleman, R.G., Lee, D.E., Beatty, L.B., Brannock, W.W.: Eclogites and eclogites: their differences and similarities. Geol. Soc. Am. Bull. 76, 483–504 (1965)

    Google Scholar 

  • Evans, B.W., Trommsdorff, V.: Petrogenesis of garnet lherzolite, Cima Di Gagnone, Lepontine Alps. Earth Planet. Sci. Lett. 40, 333–348 (1978)

    Google Scholar 

  • Evans, B.W., Trommsdorff, V., Richter, W.: Petrology of an eclogite-metarodingite suite at Cima di Gagnone, Ticino, Switzerland. Am. Mineral. 64, 15–31 (1979)

    Google Scholar 

  • Ganguly, J.: Activity-composition relation of Jadeite in omphacite pyroxene: Theoretical deductions. Earth Planet. Sci. Lett. 19, 145–153 (1973)

    Google Scholar 

  • Ganguly, J.: The energetics of natural garnet solution: II. Mixing of the calcium-silicate end-members. Contrib. Mineral. Petrol. 55, 81–90 (1976)

    Google Scholar 

  • Ganguly, J.: Garnet solid solution and geothermometry based on Fe-Mg distribution coefficient (abstracts). EOS 59. 395 (1978)

    Google Scholar 

  • Ganguly, J., Kennedy, G.C.: The energetics of natural garnet solid solution: I. Mixing of the alumino-silicate end-members. Contrib. Mineral. Petrol. 48, 137–148 (1974)

    Google Scholar 

  • Green, D.H.: Mineralogy of two Norwegian eclogites. In: Contributions to physico-chemical petrology (in Russian). Vol. 1, pp. 37–44. Khorzinskii volume 1969

  • Green, D.H., Ware, N.G., Hibberson, W.O.: Experimental petrology and petrogenesis of Apollo 14 basalts. Proc. 3rd Lunar Sci. Conf. (Suppl. 3, Geochim. Cosmochim. Acta) 1, 197–206 (1972)

    Google Scholar 

  • Green, D.H., Ware, N.G., Hibberson, W.O., Major, A.: Experimental petrology of Apollo 12 basalts: Parti, Sample 12009. Earth Planet. Sci. Lett. 13, 85–96 (1971)

    Google Scholar 

  • Green, D.H., Ringwood, A.E.: An experimental investigation of the gabbro to eclogite transformation and its petrological applications. Geochim. Cosmochim. Acta 31, 767–833 (1967)

    Google Scholar 

  • Hensen, B.J.: Pyroxenes and garnets as geothermometers and geobarometers. Ann. Kept. Dir. Carnegie Inst. Washington Yearb. 72, 527–534 (1973)

    Google Scholar 

  • Hensen, B.J., Schmid, R., Wood, B.J.: Activity-composition relationships for pyrope-grossular garnet. Contrib. Mineral. Petrol. 51, 161–166 (1975)

    Google Scholar 

  • Irving, A.J.: Geochemical and high pressure experimental studies of garnet pyroxenite and pyroxene granulite xenoliths from the Delegate basaltic pipes, Australia. J. Petrol. 15, 1–40 (1974)

    Google Scholar 

  • Ito, K., Kennedy, G.C.: Melting and phase relations in the plane tholeiite-lherzolite-nepheline basanite to 40 kbar with geological implications. Contrib. Mineral. Petrol. 19, 177–211 (1968)

    Google Scholar 

  • Kushiro, I., Shimizu, N., Nakamura, Y.: Compositions of coexisting liquid and solid phases formed upon melting of natural garnet and spinel lherzolites at high pressures: a preliminary report. Earth Planet. Sci. Lett. 14, 19–25 (1972)

    Google Scholar 

  • Kushiro, I., Syono, Y., Akimoto, S.: Effect of pressure on garnetpyroxene equilibrium in the system MgSiO3-CaSiO3-Al2O3. Earth Planet. Sci. Lett. 2, 460–464 (1967)

    Google Scholar 

  • Lovering, J.F., White, A.J.R.: Granulitic and eclogitic inclusions in basic pipes at Delegate, Australia. J. Petrol. 21, 9–52 (1969)

    Google Scholar 

  • McCallister, R.H., Finger, L.W., Ohashi, Y.: Intracrystalline Fe2+-Mg equilibria in three natural Ca-rich clinopyroxenes. Am. Mineral. 61, 671–676 (1976)

    Google Scholar 

  • Mori, T., Green, D.H.: Laboratory duplication of phase equilibria observed in natural garnet lherzolites. J. Geol. 86, 83–97 (1978)

    Google Scholar 

  • Mysen, B., Heier, K.S.: Petrogenesis of eclogites in high grade metamorphic gneisses exemplified by the Hareidland Eclogite, Western Norway. Contrib. Mineral. Petrol. 36, 73–94 (1972)

    Google Scholar 

  • Newton, R.C.: Thermochemistry of garnets and aluminous pyroxenes in the CMAS system. In: Thermodynamics in Geology (D.G. Fraser, ed.), 29–55, 410p. Dordrecht, Boston: D. Reidel Publishing Company 1977

    Google Scholar 

  • Newton, R.C., Charlu, T.V., Kleppa, O.J.: Thermochemistry of high pressure garnets and clinopyroxenes in the system CaO-MgO-Al2O3-SiO2. Geochim. Cosmochim. Acta 41, 369–377 (1977)

    Google Scholar 

  • Novak, G.A., Gibbs, G.V.: The crystal chemistry of the silicate garnets. Am. Mineral. 56, 791–825 (1971)

    Google Scholar 

  • Råheim, A., Green, D.H.: Experimental determination of the temperature and pressure dependence of the Fe-Mg partition coefficient for coexisting clinopyroxene and garnet. Contrib. Mineral. Petrol. 48, 179–203 (1974a)

    Google Scholar 

  • Råheim, A., Green, D.H.: Experimental petrology of lunar highland basalt composition and applications to models for the lunar interior. J. Geol. 82, 607–622 (1974b)

    Google Scholar 

  • Reed, S.J.B., Ware, N.G.: Quantitative electron microprobe analysis of silicates using energy dispersive X-ray spectrometry. J. Petrol. 16, 499–519 (1975)

    Google Scholar 

  • Rutstein, M.S., Yund, R.A.: Unit-cell parameters of synthetic diopside-hedenbergite solid solutions. Am. Mineral. 54, 238–245 (1969)

    Google Scholar 

  • Ryburn, R.J., Råheim, A., Green, D.H.: Determination of the P, T paths of natural eclogites during metamorphism-record of subduction. Lithos 9, 161–164 (1975)

    Google Scholar 

  • Saxena, S.K.: Thermodynamics of rock-forming crystalline solutions. Minerals and Rocks, vol. 8, Springer-Verlag, Heidelberg (1973)

    Google Scholar 

  • Saxena, S.K., Ghose, S., Turnock, A.C.: Cation distribution in lowcalcium pyroxenes: Dependence on temperature and calcium content and the thermal history of lunar and terrestrial pigeonites. Earth Planet. Sci. Lett. 21, 194–200 (1974)

    Google Scholar 

  • Saxena, S.K., Nehru, C.E.: Enstatite-diopside solvus and geothermometry. Contrib. Mineral. Petrol. 49, 259–267 (1975)

    Google Scholar 

  • Smyth, J.R., Hatten, C.J.: A coesite-sanidine grospydite from the Roberts Victor kimberlite. Earth Planet. Sci. Lett. 34, 284–290 (1977)

    Google Scholar 

  • Takahashi, T., Liu, L.G.: Compression of ferromagnesian garnets and the effect of solid solutions on the bulk shear modulus. J. Geophys. Res. 71, 5757–5766 (1970)

    Google Scholar 

  • Thompson, J.B. Jr.: Thermodynamic properties of simple solutions. In: Researches in geochemistry (P.H. Abelson, ed.), Vol. 2, pp. 340–361 (1967)

  • Warner, R.D., Luth, W.C.: The diopside-orthoenstatite two phase region in the system CaMgSi2O6-Mg2Si2O6. Am. Mineral. 59, 98–109 (1974)

    Google Scholar 

  • Wells, P.R.A.: Pyroxene thermometry in simple and complex systems. Contrib. Mineral. Petrol. 62, 129–139 (1977)

    Google Scholar 

  • Wood, B.J.: The influence of pressure, temperature and bulk composition on the appearance of garnet in ortho-gneisses-an example from South Harris, Scotland. Earth Planet. Sci. Lett. 26, 299–311 (1975)

    Google Scholar 

  • Wood, B.J.: The partitioning of iron and magnesium between coexisting garnet and clinopyroxene. Ann. Rep. Dir. Carnegie Inst. Washington Yearb. 75, 571–574 (1976)

    Google Scholar 

  • Wood, B.J.: The activities of components in clinopyroxene and garnet solid solutions and their application to rocks. Philos. Trans. R. Soc. London, Ser. A: 286, 331–342 (1977)

    Google Scholar 

  • Yoder, H.S., Tilley, C.E.: Origin of basalt magmas: an experimental study of natural and synthetic rock systems. J. Petrol. 3, 342–532 (1962)

    Google Scholar 

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  1. D. J. Ellis

    Present address: Institut für Kristallographie und Petrographie ETH-Zentrum, CH-8092, Zürich, Switzerland

Authors and Affiliations

  1. Department of Geology, University of Tasmania, Hobart, Tasmania, Australia

    D. J. Ellis & D. H. Green

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Ellis, D.J., Green, D.H. An experimental study of the effect of Ca upon garnet-clinopyroxene Fe-Mg exchange equilibria. Contr. Mineral. and Petrol. 71, 13–22 (1979). https://doi.org/10.1007/BF00371878

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