Phase Diagram Movies Home

Movies of phase diagrams for adiabatic decompression melting of peridotite and pyroxenite. Includes mixed sources that are in thermal but not chemical equilibrium. Flash not required for browsing movies.

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This suite of binary phase diagram ‘movies’ can be used to understand the energetic balances controlling isentropic melt productivity of coexisting pyroxenite and peridotite sources that are in thermal but not chemical equilibrium. Scripts allow movies for multiple plots (e.g. S-X, P-T and melt fraction versus pressure) to be viewed and controlled simultaneously. The user may choose between many different systems, homogeneous or heterogeneous sources, with variable mixing proportions, and batch or fractional melting regimes.

The solid and liquid phases used in the thermodynamic calculations are based on end-member phases in the MELTS database, with some tweaks for extrapolation to high enough pressures to freeze the 'pyroxenite' source. All the binary systems (e.g. forsterite-enstatite, forsterite-quartz) are simplified in the sense that sub-solidus reactions that do not affect melting at the compositions of interest are ignored. Some systems, such as olivine-orthopyroxene, are constructed in way that is not totally realistic for the phases involved but rather mimics the behavior of mantle lithologies as a whole (e.g. limited solid solution between olivine and opx allows the model 'peridotite' and 'pyroxenite' to melt simultaneously, albeit briefly). Systems labelled as 'simplified' are further adjusted so that solidii of the constituent phases are sub-parallel so that competing effects on the melt productivity may be separated.


In Smith et al. 2003, we presented preliminary calculations on the energetics of melting of peridotite-pyroxenite ‘marble-cake’ mantle, in the limit of chemical isolation but thermal equilibrium between the lithologies. The strongest result was that sorting a given bulk composition into different lithologies cannot yield large amounts of extra melt production compared to melting the uniform source, although the balance of contributions from high pressure (eclogite) and low pressure (peridotite) melts is perturbed. Following the approach established in Asimow et al. (1995; 1997) and Asimow & Stolper (1999) we showed that this is the case both in the natural system (using an extension of Adiabat_1ph that we are currently incorporating into libalphaMELTS) and in carefully constructed binary systems.

Originally the files were in QuickTimeTM format and composite movies were assembled manually but the large file sizes involved did not lend themselves well to presentation. As part of the original development of the MAGMA website, all the binary phase diagrams were remade in Flash format and CGI scripts were written to control movie playback. At the time, browser plugins and standalone players were widely available but, as some devices did not support Flash (most notably the iPad) we started converting the movies using Google's Swiffy tool (now no longer available).

Go straight to the Movie Selector!

Adobe recently announced that they will withdraw support for Flash in 2020. We are working on a new movie server that will not use Flash during playback at all. In the meantime, we have installed Mozilla's Shumway on the server side so that you may view movies as HTML5 objects instead. If you would like to be able to use the movie controls, but you prefer not to install the Flash plugin, then we recommend downloading Google Chrome (or using Microsoft Edge, if available). Chrome and Edge have built-in Flash players, and you can choose to restrict Flash to certain sites. Composite movies with full controls, which may be played off-line, are also available. Please see the Documentation page, linked to the right, for more details on these and other options.