Search in Google Scholarīarclay, J., and Carmichael, I.S.E. Adiabatic decompression and the composition and mean properties of mid-ocean ridge basalts. (2001) Calculation of peridotite partial melting from thermodynamic models of minerals and melts, IV. Search in Google ScholarĪsimow, P.D., Hirschmann, M.M., and Stolper, E.M. Carnegie Institution of Washington Yearbook, 76, 553–557. (1977) Partitioning of nickel between olivine and ultrabasic and basic komatiite liquids. (2007) The effect of H2O on olivine crystallization in MORB: experimental calibration at 200 MPa. Search in Google ScholarĪlmeev, R.A., Holtz, F., Koepke, J., Parat, F., and Botcharnikov, R.E. (1989) Petrology of lavas from the Lamont Seamount Chain and adjacent East Pacific Rise, 10°N. Search in Google ScholarĪllan, J.F., Batiza, R., Perfit, M.R., Fornari, D.J., and Sack, R.O. Contributions to Mineralogy and Petrology, 105, 243–254. (1990) Aluminum partitioning between olivine and ultrabasic silicate liquid to 6 GPa. References citedĪgee, C.B., and Walker, D. Garcia significantly improved this paper. Thoughtful and constructive reviews by C. We thank Adam Kent, Richard Bradshaw, and Andy Ungerer for their help with the LA-ICP-MS analysis at Oregon State University. This study was supported by National Science Foundation grant (EAR-1551344). More hydrous experiments are needed to confirm that the Ni-thermometer can be applied to hydrous melts without a correction for H 2O in the melt. Is less sensitivite to water in the melt, which is supported by new Ni-partitioning results on three olivine-melt equilibrium experiments on a basaltic andesite with up to 5 wt% H 2O. Therefore, the reason why hydrous arc basalts have higher Δ T ( T Mg – T Ni) values than MORBs may be because Is affected by dissolved water in the melt and that Mg-thermometers overestimate the temperature of hydrous basalts if an H 2O correction is not applied (e.g., Putirka et al. It is well documented in the literature that In contrast, application of the two thermometers to 18 subduction-zone basalts leads to an average Δ T of +112° this large positive Δ T value cannot be explained by the effect of pressure, temperature or anhydrous melt composition. Application of the two thermometers to nine mid-ocean ridge basalts results in an average Δ T of –3°, consistent with shallow crystallization of olivine under nearly anhydrous conditions.
Therefore, neglecting the effect of pressure when applying both thermometers to basalts that crystallized olivine at crustal depths ( ≤1 GPa) is expected to lead to negative Δ T ( T Mg – T Ni) values ( ≤ –52 ☌). (2013), whereas the pressure dependence of the Mg-thermometer is up to 52 ☌ at ≤1 GPa ( Herzberg and O’Hara 2002). The pressure dependence of the Ni-thermometer under crustal conditions ( ≤1 GPa) is shown to be negligible through comparison with experimental results from Matzen et al.
When both thermometers are applied to the same 123 experiments, the average Δ T ( T Mg – T Ni) is 1 ± 29 ☌ (1σ), which confirms that the Mg- and Ni-thermometers perform equally well over a wide range of anhydrous melt composition and temperature at 1 bar. A re-fitted version of the Mg-thermometer of Beattie (1993), calibrated on the same 123 experiments as for the Ni-thermometer, results in an average residual of 1 ± 26 ☌ (1σ). The Ni-thermometer recovers the 123 experimental temperatures within ☒9 ☌ (1σ), with an average residual of 0 ☌.
The final data set spans a wide range of temperatures (1170–1650 ☌), liquid compositions (37–66 wt% SiO 2 4–40 wt% MgO 107–11 087 ppm Ni), and olivine compositions (Fo 36-100 0.10–15.7 wt% NiO). It is calibrated on a data set of 123 olivine-melt equilibrium experiments from 16 studies in the literature that pass the following five filters: (1) 1 bar only, (2) analyzed totals between 99.0–101.0 wt% for olivine and 98.5–101.0 wt% for quenched glasses, (3) olivine is the only silicate phase in equilibrium with the melt, (4) the NiO concentration is ≥0.1 wt% in olivine and ≥0.01 wt% in quenched glass, and (5) no metallic phase is present other than the capsule. ), with a form similar to the Beattie (1993) D Mg Ol/liq A new olivine-melt thermometer based on the partitioning of Ni (
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