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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. Movies are available in Flash and HTML5.

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Introduction

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.

Background

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. Browser plugins and standalone players for Flash are widely available but for users that either prefer not to use Flash or are using devices that do not support it (most notably the iPad) we recently started converting the movies so that they can also be viewed in browsers that support HTML5.

How to view the movies

Open the Movie Selector and choose the layout and number of movies. S-X (entropy-composition) and T-X (temperature-composition) movies are the larger plots; temperature, melt fraction, melt productivity and entropy versus pressure are the smaller plots. Plots options, such as binary system, source type, mixing ratio and melt regime can be applied separately or copied to all plots. Choose between 'Heterogeneous' (pyroxenite and peridotite source in thermal but not chemical equilibrium) or 'Homogeneous' (a single source with the same bulk composition). A 'Normal' mixing ratio means that the combined pyroxene and depleted perdotite have a fertile mantle-like composition; 'Low pyroxite' gives an overall more depleted source and 'High pyroxenite' a more enriched one.

Go straight to the Movie Selector!

Buttons are provided for playing the combined movie in a browser window, downloading the .swf file, printing (displaying the frame for a chosen pressure, without movie controls, so that the image can be saved) and saving the query so that the same combination of movies can be revisited without using the Movie Selector. By default output will be in Flash and, for various reasons, the pages use frames if possible. The script should detect iPads and adjust accordingly. On any platform, you can also toggle between using and not using Flash and / or frames manually.

Known bugs and limitations:

The movie output has been most thoroughly tested in Chrome, as that is the only browser available on all the platforms that we have access to. It has been also been checked in Firefox, Safari, Internet Explorer (8 and 9) and Opera, and on Linux, Mac, Windows (XP and 7) and iPad (2nd and 4th generation) where appropriate.