Paul D Asimow

Learn More
Algorithmic modifications to the MELTS software package are presented in order that calculations of heterogeneous phase equilibria can be performed in the subsolidus. Methods are presented for: (1) selecting an ‘‘initial guess assemblage’’ that satisfies the bulk composition constraints; (2) detecting saturation of new phases (including liquid) in an(More)
[1] Several methods have been developed to assess the thermal state of the mantle below oceanic ridges, islands, and plateaus, on the basis of the petrology and geochemistry of erupted lavas. One leads to the conclusion that mantle potential temperature (i.e., TP) of ambient mantle below oceanic ridges is 1430 C, the same as Hawaii. Another has ridges with(More)
melting. This too can be demonstrated both by MELTS calculations We present a rigorous calculation of the isobaric entropy (S) change and by calculations in simple model systems. Productivities for of the melting reaction for peridotite (∂S/∂F ) P , where F is the systems enriched in incompatible components are systematically melt fraction. Calculations at(More)
[1] The major element, trace element, and isotopic composition of mid-ocean ridge basalt glasses affected by the Azores hotspot are strongly correlated with H2O content of the glass. Distinguishing the relative importance of source chemistry and potential temperature in ridge-hotspot interaction therefore requires a comprehensive model that accounts for the(More)
Composition, mean pressure, mean melt fraction, and crustal thickINTRODUCTION ness of model mid-ocean ridge basalts (MORBs) are calculated Comparison of observed basalt compositions with the using MELTS. Polybaric, isentropic batch and fractional melts predictions of polybaric mantle melting models places from ranges in source composition, potential(More)
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(More)
[1] PRIMELT2.XLS software is introduced for calculating primary magma composition and mantle potential temperature (TP) from an observed lava composition. It is an upgrade over a previous version in that it includes garnet peridotite melting and it detects complexities that can lead to overestimates in TP by >100 C. These are variations in source lithology,(More)
Progress in development of thermodynamically based models of straint on the thermal state of the Earth’s upper mantle (e.g. Klein & Langmuir, 1987; McKenzie & Bickle, 1988; silicate equilibria with explicit entropy budgets has motivated a reexamination of the conclusion of McKenzie that isentropic upwelAsimow et al., 2001). Meaningful interpretation of(More)
[1] Polycrystalline samples of Mg2SiO4 forsterite and wadsleyite were synthesized and then dynamically loaded to pressures of 39–200 GPa. Differences in initial density and internal energy between these two phases lead to distinct Hugoniots, each characterized by multiple phase regimes. Transformation to the high-pressure phase assemblage MgO + MgSiO3(More)
[1] Bymeans of static ab-initio computations we investigate the influence of Al on the recently discovered perovskite to post-perovskite phase transition in MgSiO3. We examine three substitution mechanisms for Al in the two structures: MgSi ! AlAl; SiSiO ! AlAl5; and Si ! AlH. The substitutions introducing oxygen vacancies (highly unfavorable,(More)