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  • 1
    Electronic Resource
    Electronic Resource
    An experimental study of Fe-Mg partitioning between olivine and orthopyroxene at 1173, 1273 and 1423 K and 1.6 GPa (1993)
    Springer
    Contributions to mineralogy and petrology 113 (1993), S. 196-207 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The partitioning of Mg and Fe2+ between coexisting olivines and orthopyroxenes in the system MgO-FeO-SiO2 has been investigated experimentally at 1173, 1273, 1423 K and 1.6 GPa over the whole range of Mg/Fe ratios. The use of barium borosilicate as a flux to promote grain growth, and the identification by back-scattered electron imaging of resulting growth rims suitable for analysis by electron microprobe, results in coexisting olivine and orthopyroxenene compositions determined to a precision of±0.003 to 0.004 in molar Fe/(Mg+Fe). Quasi-reversal experiments were performed starting with Mg-rich olivine and Fe-rich orthopyroxene (low KD) and vice versa (high KD), which produced indistinguishable results. The distribution coefficient, KD, depends on composition and on temperature, but near Fe/(Mg+Fe)=0.1 (i.e. mantle compositions) these effects cancel out, and KD is insensitive to temperature. The results agree well with previous experimental investigations, and constrain the thermodynamic mixing properties of Mg-Fe olivine solid solutions to show small near-symmetric deviations from ideality, with $$W_{G_{Mg - Fe}^{ol} }$$ between 2000 and 8000 J/mol. Multiple non-linear least squares regression of all data gave a best fit with $$W_{G_{Mg - Fe}^{ol} } = 5625 \pm 574 J/mol$$ (implying 5450 J/mol at 1 bar) and $$W_{G_{Mg - Fe}^{opx} } = 2145 \pm 614 J/mol$$ , but the two W G parameters are so highly correlated with each other that our data are almost equally well fit with $$W_{G_{Mg - Fe}^{ol} } = 3700 \pm 800 J/mol$$ , as obtained by Wiser and Wood. This value implies $$W_{G_{Mg - Fe}^{opx} } = 280 \pm 900 J/mol$$ , apparently independent of temperature. Our experimental results are not compatible with the assessment of olivine-orthopyroxene equilibria of Sack and Ghiorso.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00283228
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamic data from redox reactions at high temperatures. V. Thermodynamic properties of NiO−MnO solid solutions from emf measurements (1995)
    Springer
    Contributions to mineralogy and petrology 119 (1995), S. 409-421 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Divariant oxide plus metal assemblages potentially make useful redox sensors for use in hydrothermal and other high pressure experiments. Here we report the calibration of the (Ni, Mn)O/Ni redox sensor in which the Ni/NiO (NNO) oxygen buffer is displaced to lower oxygen chemical potentials (μO2), by the solid solution of MnO in the oxide phase. This assemblage was chosen because: (1) it covers a useful range of μO2; (2) the system can be calibrated very accurately. Values of μO2 defined by the (Ni, Mn)O/Ni assemblage were determined electrochemically, from 900 to 1300 K, using calcia-stabilized zirconia solid electrolytes. The oxide compositions (8 in total, ranging from 0.1≤X NiO≤0.8) were analysed afterwards by electron microprobe, and were checked for internal consistency by measuring the lattice parameters (a0), using powder XRD. The accuracies of the measurements, both assessed theoretically and established empirically, are (1σ): ±80J/mol in μO2, ±0.0002 Å in a0 and ±0.002 to 0.005 in X NiO. Activity-composition relations were fitted to the Redlich-Kister formalism. There is a slight asymmetry (corresponding to a subregular model) across the solution with A 0 G =9577(±45) J/mol, and A 1 G =−477(±80) J/mol. The experimental data were also used to derive the parameters Vex, Hex and Sex. There is no obvious relationship between excess volumes and enthalpies of mixing, nor between excess volumes and excess entropies. The experimental data from this study have been used to formulate the (Ni, Mn)O/Ni redox sensor expression: μO2 = μ2(NNO) + 2RTlnX NiO + 2(1 − X NiO)2[11483 − 1.697T] − 477(4X NiO − 1)(900 〈 T(K) 〈 1300) where μO2(NNO)=−478967+248.514T−9.7961 T In T, from O'Neill and Pownceby(1993a).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00286938
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  • 3
    Electronic Resource
    Electronic Resource
    Quests for low-degree mantle melts (1996)
    [s.l.] : Nature Publishing Group
    Nature 381 (1996), S. 285-285 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - Baker et al.1 report an experimental study at pressures of 1 GPa (1,000 million Pa) to determine the composition of a silicate melt produced at anhydrous, near-solidus conditions from a Iherzolite composition. They obtained a composition at 1,250 °C with -57% SiO2 and -5.7% Na2O, which is ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/381285a0
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  • 4
    Electronic Resource
    Electronic Resource
    Thermodynamic data from redox reactions at high temperatures. II. The MnO-0Mn3O4 oxygen buffer, and implications for the thermodynamic properties of MnO and Mn3O4 (1993)
    Springer
    Contributions to mineralogy and petrology 114 (1993), S. 315-320 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The $$\mu _{O_2 } $$ defined by the reaction 6 MnO+O2 =2 Mn3O4 has been determined from 917 to 1,433 K using electrochemical cells (with calcia-stabilized zirconta, CSZ) of the type: Steady emfs were achieved rapidly at all temperatures on both increasing and decreasing temperature, indicating that the MnO-Mn3O4 oxygen buffer equilibrates relatively easily. It therefore makes a useful alternative choice in experimental petrology to Fe2O3-Fe3O4 for buffering oxygen potentials at oxidized values. The results are (in J/mol, temperature in K, reference pressure 1 bar); $$\mu _{O_2 } $$ (±200)=-563,241+1,761.758T-220.490T inT+0.101819T 2 with an uncertainty of ±200 J/mol. Third law analysis of these data, including a correction for the deviations in stoichiometry of MnO, impliesS 298.15 for Mn3O4 of 166.6 J/K · mol, which is 2.5 J/K · mol higher than the calorimetric determination of Robie and Hemingway (1985). The low value of the calorimetric entropy may be due to incomplete ordering of the magnetic spins. The third law value of Δ r H 298.15 0 is-450.09 kJ/mol, which is significantly different from the calorimetric value of-457.5±3.4 kJ/mol, calculated from Δ f H 298.15 0 of MnO and Mn3O4, implying a small error in one or both of these latter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046534
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  • 5
    Electronic Resource
    Electronic Resource
    Thermodynamic data from redox reactions at high temperatures. I. An experimental and theoretical assessment of the electrochemical method using stabilized zirconia electrolytes, with revised values for the Fe-“FeO”, Co-CoO, Ni-NiO and Cu-Cu2O oxygen buffers, and new data for the W-WO2 buffer (1993)
    Springer
    Contributions to mineralogy and petrology 114 (1993), S. 296-314 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The accuracy and reliability of high temperature thermodynamic data obtained from oxygen concentration cells with stabilized zirconia (SZ) electrolytes are assessed. The experimental apparatus and methods needed to obtain precise results are described. We then test the apparatus, firstly on symmetrical cells of the type: $$Pt, M + M_x O|CSZ|M + M_x O, Pt$$ where M=C, Ni, Co or Fe; and then by examining all the possible permutations of heterogenous cells with these four oxygen buffers. Simultaneous linear regression of all the data (624 readings from 14 different cells) shows that the overall precision of the results is ±100 J/mol (one standard deviation). The results are in good agreement with the available calorimetric data. Although the agreement with previous electrochemical work is also good, the high precision of the present results reveals small systematic differences, and accordingly we recommend small adjustments to the existing values for these buffers. The revised equations are ( $$\mu _{O_2 } $$ in J/mol, temperature in K, reference pressure 105 Pa): $$\begin{gathered} Cu - Cu_2 O( \pm 80): \hfill \\ - 347,705 + 246.096 T \hfill \\ - 12.9053 T In T (700〈 T〈 1,338) \hfill \\ Ni - NiO( \pm 200): \hfill \\ - 478,967 + 248.514 T \hfill \\ - 9.7961 T In T (700〈 T〈 1.700) \hfill \\ Co - CoO( \pm 200): \hfill \\ - 492,186 + 509.322 T - 53.284 T In T \hfill \\ + 0.02518 T^2 (700〈 T〈 1,394) \hfill \\ - 484,276 + 235,092 T \hfill \\ - 11.3440 T In T(1,394〈 T〈 1,760) \hfill \\ \end{gathered} $$ We also report new data for the W-WO2 buffer. The results, which are also in very good agreement with the calorimetric data, are: $$\begin{gathered} W - WO_2 ( \pm 300): \hfill \\ = - 569,087 + 300.479 T \hfill \\ - 15.9697 T In T(700〈 T〈 1,700) \hfill \\ \end{gathered} $$ .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046533
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  • 6
    Electronic Resource
    Electronic Resource
    Phase relations between Ca3Fe3+ 2Si3O12-Fe2+ 3Fe3+ 2Si3O12 garnet and CaFeSi2O6-Fe2Si2O6 pyroxene solid solutions (1995)
    Springer
    Contributions to mineralogy and petrology 121 (1995), S. 87-98 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100050091
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  • 7
    Electronic Resource
    Electronic Resource
    An experimental study of Fe-Mg partitioning between garnet and olivine and its calibration as a geothermometer: Corrections (1980)
    Springer
    Contributions to mineralogy and petrology 72 (1980), S. 337-337 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376154
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  • 8
    Electronic Resource
    Electronic Resource
    The transition between spinel lherzolite and garnet lherzolite, and its use as a Geobarometer (1981)
    Springer
    Contributions to mineralogy and petrology 77 (1981), S. 185-194 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The equilibrium between spinel lherzolite and garnet lherzolite has been experimentally determined in the CaO-MgO-Al2O3-SiO2 system between 800° and 1,100° C. In confirmation of earlier work and predictions from thermodynamic data, it was found that theP-T slope of the reaction was close to zero, the equilibrium ranging from 16.1 kb at 800° C to 18.7 kb at 1,100° C (±0.3 kb). The addition of Cr2O3 to the system raised the stability field of spinel to higher pressures. It was found that the pressure at which both garnet and spinel could exist with olivine+orthopyroxene+clinopyroxene in the system CMAS −Cr2O3 could best be described by the empirical relationship: $$P = P^{\text{O}} + \alpha X_{{\text{Cr}}}^{s{\text{p}}} $$ whereP 0 is the equilibrium pressure for the univariant reaction in the Cr2O3-free system,α is a constant apparently independent of temperature with a value of 27.9 kilobars, andX Cr sp is the mole fraction of chromium in spinel. Use was made of the extensive literature on Mg-Fe2+ solid solutions to quantitatively derive the effect of Fe2+ on the equilibrium. The effect of other components (Fe3+, Na) was also considered. The equilibrium can be used as a sensitive geobarometer for rocks containing the five phases ol+opx+cpx+gt+sp, and thus provides the only independent check presently available for the more widely applicable geobarometer which uses the alumina content of orthopyroxene in equilibrium with garnet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00636522
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  • 9
    Electronic Resource
    Electronic Resource
    An experimental study of Fe-Mg partitioning between garnet and olivine and its calibration as a geothermometer (1979)
    Springer
    Contributions to mineralogy and petrology 70 (1979), S. 59-70 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The partitioning of Fe and Mg between coexisting garnet and olivine has been studied at 30 kb pressure and temperatures of 900 ° to 1,400 °C. The results of both synthesis and reversal experiments demonstrate that K D (= (Fe/Mg)gt/(Fe/Mg)OI) is strongly dependent on Fe/Mg ratio and on the calcium content of the garnet. For example, at 1,000 °C/30 kb, K D varies from about 1.2 in very iron-rich compositions to 1.9 at the magnesium end of the series. Increasing the mole fraction of calcium in the garnet from 0 to 0.3 at 1,000 ° C increases K D in magnesian compositions from 1.9 to about 2.5. The observed temperature and composition dependence of K D has been formulated into an equation suitable for geothermometry by considering the solid solution properties of the olivine and garnet phases. It was found that, within experimental error, the simplest kind of nonideal solution model (Regular Solution) fits the experimental data adequately. The use of more complex models did not markedly improve the fit to the data, so the model with the least number of variables was adopted. Multiple linear regression of the experimental data (72 points) yielded, for the exchange reaction: 3Fe2SiO4+2Mg3Al2Si3O12 olivine garnet ⇌ 2Fe2Al2Si3O12+3Mg2SiO4 garnet olivine ΔH ° (30kb) of −10,750 cal and ΔS ° of −4.26 cal deg−1 mol−1. Absolute magnitudes of interaction parameters (W ij ) derived from the regression are subject to considerable uncertainty. The partition coefficient is, however, strongly dependent on the following differences between solution parameters and these differences are fairly well constrained: W FeMg ol -W FeMg gt ≃ 800 cal W CaMg gt -W CaFe gt ≃ 2,670 cal. The geothermometer is most sensitive in the temperature and composition regions where K D is substantially greater than 1. Thus, for example, peridotitic compositions at temperatures less than about 1,300 ° C should yield calculated temperatures within 60 °C of the true value. Iron rich compositions (at any temperature) and magnesian compositions at temperatures well above 1,300 °C could not be expected to yield accurate calculated temperatures. For a fixed K D the influence of pressure is to raise the calculated temperature by between 3 and 6 °C per kbar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371872
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  • 10
    Electronic Resource
    Electronic Resource
    Fe-Mn partitioning between garnet and ilmenite: experimental calibration and applications (1987)
    Springer
    Contributions to mineralogy and petrology 97 (1987), S. 116-126 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A new mineralogic geothermometer based on the partitioning of Fe and Mn between garnet and ilmenite has been calibrated by reversal experiments in the P-T range 600–900° C, 2 and 5 kbars and for fO2=QFM. The results constitute a sensitive geothermometer applicable over a broad range of composition and conditions. Garnetilmenite thermometry has advantages relative to existing geothermometers because of its accurate calibration, marked temperature sensitivity and the chemical and structural simplicity of the crystalline solutions involved. Application to natural assemblages reveals that the garnet-ilmenite geothermometer yields temperatures that agree well with other estimates. The reactivity of, and relatively rapid Fe-Mn diffusion in ilmenite may lead to retrograde resetting of high temperature partition values, but these factors may be useful for estimating rock cooling rates. Analysis of the experimental data indicates minor positive deviations from ideality for Fe-Mn garnets and ilmenites. Absolute magnitudes of interaction parameters (W AB) derived from a regression analysis are subject to considerable uncertainty. The partition coefficient is, however, strongly dependent on the difference between solution parameters. These differences are well constrained with a magnitude of W FeMn ilm −W FeMn gar ≃300 cal mol−1. The accuracy and applicability of garnet-ilmenite thermometry will improve with the availability of better thermodynamic data for garnet crystalline solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375219
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