Melt-PX    How to use it    Download    doi:10.1016/j.lithos.2012.11.018    Corresponding abstract

 

How to use Melt-PX

The first worksheet, “Melt-PX”, calculates the extent of isobaric batch melting of one or two pyroxenite compositions entered by the user at a user-specified pressure (P) and temperature (T).
Input parameters are: the major-element compositions of the pyroxenites (in wt. %) and the pressure and temperature conditions. An error message (in red) appears if the input parameters fall outside of the condition range used to calibrate the model. A Comment (in blue) appears if T5% or T>Tcpx-out. For T>Tcpx-out, melt fraction (F') calculated with a constant melt productivity equal to 0.3%/°C above the cpx-out also appears. F calculation will not be performed if Tcpx-out5%% and the message "Error: cpx-free assemblage" will appear instead.

The second worksheet, "Decompression melting" (represented on the figure) models the adiabatic decompression melting of a two-lithology mantle (pyroxenite and peridotite) in which the pyroxenite, depending on its composition, can start to melt before or after the peridotite.
This spreadsheet uses Melt-PX for the melting functions of the pyroxenite, Katz et al.'s parameterization (2003) for the melting functions of the peridotite and the thermodynamic treatment of adiabatic decompression fractional melting described in Text S5 of the Supplementary Information.
The composition of the pyroxenite has to be entered in the column "Pyr A" in the "Melt-PX" sheet.
Input parameters (in yellow) are: Mantle potential temperature, fraction of pyroxenite in the source (fraction of lherzolite in the source, in blue, calculated automatically), mass fraction of cpx in the subsolidus assemblage of the lherzolite, choice for reduced pyroxenite melt productivity after cpx exhaustion.
Pre-defined parameters (in green) are the thermodynamic variables. The rational for these values is discussed in the paper and is based on literature data. These are adjustable parameters.

The third worksheet, "ranges" lists all the bulk compositions that were used in our parameterization (in mol.% and in wt.%), as well as the ranges of pressure and temperature.

Both “Melt-PX” and “Decompression Melting” are locked to avoid operating errors. The password to unlock them is "pyroxenite".
You can edit online the workbook displayed bellow on this page. To zoom in/out, use your browser zoom, i.e. "CTRL + mouse scroll".
The model and example of applications are described in detail in: Lambart, S., M. B. Backer, and E. M. Stolper. "The role of pyroxenite in basalt genesis: Melt-PX, a melting parameterization for mantle pyroxenites between 0.9 and 5 GPa". Published in Journal of Geophysical Research - Solid Earth.

 

 
 

Dr Sarah Lambart
School of Earth and Ocean Sciences, Cardiff University
1.37, Main Building
Park Place, Cardiff, CF10 3AT, United Kingdom