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Phase diagrams of the FeO-MgO-SiO2 system and the structure of the mantle discontinuities

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Abstract

Internally consistent thermodynamic computation of equilibria in the FeO-MgO-SiO2 system up to 300 kbar is carried out and phase diagrams and profiles of the elastic properties and density are constructed at the depths of 300–800 km. Comparisons of calculated thermodynamic properties for different petrological models with seismic velocity profiles have been used to constrain the mineralogy of the mantle discontinuities. The 400-km discontinuity may represent the univariant or divariant transition in the olivine component of pyrolite as well as a chemical boundary. For the pyrolite composition at the depth of 650 km there are two different spinel + perovskite + stishovite (640 km) and magnesiowustite + spinel + perovskite (650 km) divariant loops (1–2 km wide) separated by a Invariant zone spinel + perovskite (4–6 km wide). The results indicate that phase changes in pyrolite do not explain the 650-km discontinuity. It is also shown that it is impossible to match the seismic properties observed at the depths of 600–800 km and through the discontinuity with any isochemical petrological model considered in the FMS system. However, increasing the iron content or silica and iron contents across the 650-km discontinuity can produce thermodynamic properties in the lower mantle that are more consistent with those inferred from seismic observations. Constraints on the SiO2 and iron contents in the mantle are inferred from the comparison of thermodynamic and seismological data.

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References

  • Akaogi M, Navrotsky A, Yagi T, Akimoto S (1987) Pyroxenegarnet transformation: thermochemistry and elasticity of garnet solid solutions and application to a pyrolite mantle. In: Manghnani MH, Syono Y (eds) High-pressure research in mineral physics. The Akimoto Volume. Geophys Monograph 39 Terra Sci Pub Co Tokyo, pp 251–260

    Google Scholar 

  • Anderson DL (1977) Composition of the mantle and core. Annu Rev Earth Planet Sci 5:179–202

    Google Scholar 

  • Anderson DL (1988) Bulk chemistry and compositional stratification of the Earth. Conference on the Origin of the Earth, pp 4–5

  • Anderson DL, Bass JD (1986) Transition region of the Earth's upper mantle. Nature 320:321–328

    Google Scholar 

  • Bass JD, Anderson DL (1984) Composition of upper mantle: geophysical tests of two petrological models. Geophys Res Lett 11:237–240

    Google Scholar 

  • Bina CR, Wood BJ (1987) Olivine-spinel transitions: experimental and thermodynamic constrains and implications for the nature of the 400-km seismic discontinuity. J Geophys Res 92:4853–4866

    Google Scholar 

  • Bock G, Ha J (1984) Short-period S-P conversion in the mantle at a depth near 700-km. Geophys JR Astron Soc 77:393–615

    Google Scholar 

  • Bonczar LJ, Graham EK (1982) The pressure and temperature dependence of the elastic properties of polycrystal magnesiowustite. J Geophys Res 87:1061–1078

    Google Scholar 

  • De Paolo DJ (1988) Neodymium Isotope Geochemistry. An Introduction. Springer, Berlin Heidelberg New York, p 187

    Google Scholar 

  • Duffy TS, Anderson DL (1989) Seismic velocities in mantle minerals and the mineralogy of the upper mantle. J Geophys Res 94, 82:1895–1912

    Google Scholar 

  • Dziewonski A, Anderson DL (1981) Preliminary reference Earth model. Phys Earth Planet Inter 25:297–356

    Google Scholar 

  • Fabrichnaya OB, Kuskov OL (1991) Constitution of the mantle: 1. Phase relations for the FeO-MgO-SiO2 system at pressure 10–30 GPa. Phys Earth Planet Inter

  • Fukao J, Nagahashi T, Mori S (1982) Shear velocity in the mantle transition zone. In: Akimoto S, Manghnani MH (eds) HighPressure Research in Geophysics: Center for Acad Publ Tokyo, pp 285–300

    Google Scholar 

  • Grand SP, Helmberger DV (1984) Upper mantle shear structure of North America. Geophys JR Astron Soc 76:399–438

    Google Scholar 

  • Irifune T (1987) An experimental investigation of the pyroxenegarnet transformation in pyrolite composition and its bearing on the constitution of the mantle. Phys. Earth Planet Inter 45:324–336

    Google Scholar 

  • Irifune T, Ringwood AE (1987) Phase transformations in primitive MORB and pyrolite compositions to 25 GPa and some geophysical implications. In: Manghnani MH, Syono Y (eds) High-Pressure Research in Mineral Physics. The Akimoto Volume Geophys Monograph 39 Terra Sci Pub Co Tokyo, pp 231–242

    Google Scholar 

  • Ito E, Takahashi E (1988) Post-spinel transformations in the system Mg2SiO4-Fe2SiO4 and some geophysical implications. Techn Report of ISEI Misasa: Okayama Univ ser A 17:1–17

    Google Scholar 

  • Ito E, Takahashi E, Matsui Y (1984) The mineralogy and chemistry of lower mantle: An implication of the ultrahigh-pressure phase relations in the system MgO-FeO-SiO2. Earth Planet Sci Lett 67:238–248

    Google Scholar 

  • Jackson I (1983) Some geophysical constraints on the chemical composition of the Earth's lower mantle. Earth Planet Sci Lett 62:91–103

    Google Scholar 

  • Jackson I, Liebermann RC, Ringwood AE (1978) The elastic properties of (Mg x Fe1-x )O solid solutions. Phys Chem Minerals 3:11–31

    Google Scholar 

  • Jeanloz R, Hazen RM (1983) Compression, nonstoichiometry and bulk viscosity of wustite. Nature 304:620–622

    Google Scholar 

  • Jeanloz R, Knittle E (1989) Density and composition of the lower mantle. Philos Trans R Soc London ser A328:377–389

    Google Scholar 

  • Jeanloz R, Sato-Sorenson Y (1986) Hydrostatic compression of Fe1-x O wustite. J Geophys Res 91:4665–4672

    Google Scholar 

  • Jeanloz R, Thompson AB (1983) Phase transitions and mantle discontinuities. Rev Geophys Space Phys 21:51–74

    Google Scholar 

  • Karpov IK, Kiselev AI, Letnikov FA (1976) Computer modelling of natural mineral formation. Nedra Publ Moscow, p 256

    Google Scholar 

  • Kind R, Vinnik LP (1988) The upper-mantle discontinuities under-neath the GRF array from P-to-S converted phases. J Geophys 62:138–147

    Google Scholar 

  • Knittle E, Jeanloz R (1987) Synthesis and equation of state of (Mg,Fe)SiO3 perovskite to over 100 Gigapascals. Science 235:668–670

    Google Scholar 

  • Kuskov OL (1987) Thermodynamics of minerals of the mantle transition zone. Pure Appl Chem 59:73–78

    Google Scholar 

  • Kuskov OL (1988) Topology of mineral-system phase diagrams and deep-focus earthquakes. Geochem Int 25:3 28–39

    Google Scholar 

  • Kuskov OL, Fabrichnaya OB (1986) Phase diagrams for the Co2SiO4-Mg2SiO4 and Fe2SiO4-Ni2SiO4 binary systems at upper mantle T and P. Geochem Int 23:4 105–120

    Google Scholar 

  • Kuskov OL, Fabrichnaya OB (1987) Phase relationships in the FeO-MgO-SiO2 system, virtual β-Fe2SiO4, and petrological and geophysical applications. Geochem Int 24:9 56–71

    Google Scholar 

  • Kuskov OL, Fabrichnaya OB (1990) Phase relations in the FeO -MgO-SiO2 system at the boundary between transition zone and lower mantle. Geokhimiya 2:266–278

    Google Scholar 

  • Kuskov OL, Galimzyanov RF (1986) Thermodynamics of stable mineral assemblages of the mantle transition zone. In: Saxena SK (ed) Chemistry and Physics of Terrestrial Planets. Adv Phys Geochem, Vol. 6, Springer, Berlin Heidelberg New-York, pp 310–361

    Google Scholar 

  • Kuskov OL, Panferov AB (1989a) Profiles of the elastic parameters and density for the olivine model mantle at the depths of 350–550 km. Izv USSR Acad Sci ser Physics of the Earth 1:13–19

    Google Scholar 

  • Kuskov OL, Panferov AB (1989b) Elastic property profiles in the mantle based on the phase transitions in the MgO-SiO2 system. Geokhimiya 9:1344–1353

    Google Scholar 

  • Kuskov OL, Fabrichnaya OB, Galimzyanov RF, Truskinovsky LM (1989) Computer simulation of the phase diagram for the MgO-SiO2 system at P-T parameters of the mantle transition zone. Phys Chem Minerals 16:442–454

    Google Scholar 

  • Lees AC, Bukowinski MST, Jeanloz R (1983) Reflection properties of phase transition and compositional change models of the 670-km discontinuity. J Geophys Res 88:8145–8159

    Google Scholar 

  • Leven JH (1985) The application of synthetic seismograms to the interpretation of the upper mantle P-wave velocity structure in northern Australia. Phys Earth Planet Inter 38:9–27

    Google Scholar 

  • Liu L (1979) On the 650-km discontinuity. Earth Planet Sci Lett 42:202–208

    Google Scholar 

  • Liu L (1982) Chemical inhomogeneity of the mantle: geochemical considerations. Geophys Res Lett 9:124–126

    Google Scholar 

  • Liu M, Liu L (1987) Bulk moduli of wustite and periclase: a comparative study. Phys Earth Planet Inter 45:273–279

    Google Scholar 

  • Montagner J-P, Anderson DL (1989) Constrained reference mantle model Phys. Earth Planet Inter 58:205–227

    Google Scholar 

  • Nakada M, Hashizume M (1983) Upper mantle structure beneath the Canadian shield derived from higher modes of surface waves. J Phys Earth 31:387–405

    Google Scholar 

  • Ohtani E, Kagawa N (1989) Stability of tetragonal garnet (Mg,Fe)SiO3 and hydrous mineral phase B at high pressure and temperature. In: Phase Transformations at High Pressures and High Temperatures: Applications to Geophys and Petrol Problems. DELP Misasa Intern Symposium and the Second Japan-USSR Symposium Misasa:87–90

  • Paulssen H (1988) Evidence for the small scale structure of the upper mantle. PhD Thesis Inst of Earth Sciences University of Utrecht, p 109

  • Richter FM, McKenzie DP (1981) On some consequences and possible causes of layered mantle convection. J Geophys Res 86:6133–6142

    Google Scholar 

  • Stark PB, Frohlich CJ (1985) The depths of the deepest deep earthquakes. J Geophys Res 90:1859–1869

    Google Scholar 

  • Truskinovsky LM, Kuskov OL, Khitarov NI (1983) Adiabatic gradient in the mantle transition zone. Geokhimiya 9:1222–1238

    Google Scholar 

  • Truskinovsky LM, Kuskov OL, Khitarov NI (1985) Adiabatic gradient in the mantle transition zone: Divariant transitions. Geokhimiya 5:579–593

    Google Scholar 

  • Walck MC (1984) The P-wave upper mantle structure beneath an active spreding center: the Gulf of California. Geophys JR Astron Soc 76:697–723

    Google Scholar 

  • Watt JP, Ahrens TJ (1982) The role of iron partitioning in mantle composition, evolution, and scale of convection. J Geophys Res 87:5631–5644

    Google Scholar 

  • Weidner DJ (1986) Mantle model based on measured physical properties of minerals. In: Saxena SK (ed) Chemistry and Physics of Terrestrial Planets. Springer, Berlin Heidelberg New York 6:251–274

  • Weidner DJ, Ito E (1987) Mineral physics constraints on a uniform mantle composition. In: Manghnani MH, Syono Y (eds) Highpressure research in mineral physics. The Akimoto volume. Geophys Monograph 39. Terra Sci Pub Co Tokyo, pp 251–260

    Google Scholar 

  • Wood BJ (1989) Mineralogical phase change at the 670-km discontinuity. Nature 341:278

    Google Scholar 

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  1. V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, USSR Academy of Sciences, 117334, Moscow, USSR

    O. L. Kuskov & A. B. Panferov

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  1. O. L. Kuskov
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  2. A. B. Panferov
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Kuskov, O.L., Panferov, A.B. Phase diagrams of the FeO-MgO-SiO2 system and the structure of the mantle discontinuities. Phys Chem Minerals 17, 642–653 (1991). https://doi.org/10.1007/BF00203845

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  • DOI: https://doi.org/10.1007/BF00203845

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