Calculation of Peridotite Partial Melting from Thermodynamic Models of Minerals and Melts. I. Review of Methods and Comparison with Experiments

Thermodynamic calculation of partial melting of peridotite using of the results of calculations of peridotite melting using MELTS, there are a number of shortcomings to application of this thermothe MELTS algorithm has the potential to aid understanding of a wide range of problems related to mantle melting. We review the dynamic model to calculations of mantle melting. In particular, calculated compositions of liquids produced by partial melting of methodology of MELTS calculations with special emphasis on the features that are relevant for evaluating the suitability of this peridotite have more MgO and less SiO2 than equivalent experimentally derived liquids. This mismatch, which is caused by thermodynamic model for simulations of mantle melting. Comparison of MELTS calculations with well-characterized peridotite partial overprediction of the stability of orthopyroxene relative to olivine, causes a number of other problems, including calculated temperatures melting experiments allows detailed evaluation of the strengths and weaknesses of the algorithm for application to peridotite melting of melting that are too high. Secondarily, the calculated distribution of Na between pyroxenes and liquid does not match experimentally problems. Calculated liquid compositions for partial melting of fertile and depleted peridotite show good agreement with experimental observed values, which leads to exaggerated calculated Na concentrations for near-solidus partial melts of peridotite. Calculations trends for all oxides; for some oxides the agreement between the calculated and experimental concentrations is almost perfect, whereas of small increments of batch melting followed by melt removal predict that fractional melting is less productive than batch melting for others, the trends with melt fraction are comparable, but there is a systematic offset in absolute concentration. Of particular interest near the solidus, where the composition of the liquid is changing rapidly, but that once the composition of the liquid ceases to change is the prediction by MELTS that at 1 GPa, near-solidus partial melts of fertile peridotite have markedly higher SiO2 than higher rapidly, fractional and batch melting produce liquid at similar rates per increment of temperature increase until the exhaustion of melt fraction liquids, but that at similar melt fractions, calculated partial melts of depleted peridotites are not SiO2 enriched. Similarly, clinopyroxene. This predicted effect is corroborated by sequential incremental batch melting experiments (Hirose & Kawamura, MELTS calculations suggest that near-solidus partial melts of fertile peridotite, but not those of depleted peridotite, have less TiO2 1994, Geophysical Research Letters, 21, 2139–2142). For melting of peridotite in response to fluxing with water, the calculated than would be anticipated from higher temperature experiments. Because both experiments and calculations suggest that these unusual effect is that melt fraction increases linearly with the amount of water added until exhaustion of clinopyroxene (cpx), at which point near-solidus melt compositions occur for fertile peridotite but not for depleted peridotite, it is highly unlikely that these effects are the the proportion of melt created per increment of water added decreases. Between the solidus and exhaustion of cpx, the amount of melt consequence of experimental or model artifacts. Despite these successes