The tr660 Program

Author: Eric Nuzzi

Project Java Webmaster: Glenn A. Richard
Center for High Pressure Research
Stony Brook University

• Description

The tr660 program was orignally written in Fortran 77 by Don Weidner of the Center for High Pressure Research (CHiPR).  The tr660 Java code was created by Eric Nuzzi, a computer science undergraduate student at SUNY Stony Brook, as part of Project Java under the supervision of Glenn Richard. The current version of the program was developed using Java 2 version 1.2.

• Scientific Information
  The tr660 program models the mineralogy and physical properties for various chemical compositions in the Earth's mantle where a transition occurs in these properties at about 660 km depth. The program is based on the algorithm described in a paper by Donald J. Weidner and Yanbin Wang (WW), published in the Journal of Geophysical Research, Vol. 103, pp. 7431-7444 in 1998. The Java program was developed from a FORTRAN code developed for this paper.

  This region of the Earth has been identified seismically as demonstrating changes in seismic velocities that cannot be explained by compression due to burial alone. Laboratory studies have demonstrated changes in mineralogy (phase) that will occur in candidate chemical compositions. The program utilizes published phase diagrams for these reactions along with published properties of the relevant phases. Some estimates, described by WW are necessary to complete the data set. This program is designed to be used for research purposed to test the effects of varying chemical composition, temperature, and physical properties on the inferred physical properties of the Earth through these phase transformations.

  Input of Data

  The chemical system is modeled in terms of 5 oxides, MgO, FeO, CaO, SiO₂, and Al₂O₃. For most models of the Earth, these oxides constitute over 95% of the bulk composition. Variables XMG, XFE, XCA, XSI, XAL represent the number of the respective cation in the calculation. The appropriate number of oxygens are added automatically for charge neutrality. The absolute value of these variables is not important, they must simply be in the appropriate ratio that the user wishes. The default value is appropriate for the pyrolite model as discussed in WW. All of these variables can be changed by the user to test alternate models.

  The phases that are included in this calculation are:

  1. CaSiO₃ in the perovskite phase (PCA)
  2. (Mg,Fe)SiO₃ in the perovskite phase (PMG) — Al does substitute into this phase with 2 Al replacing a Mg-Si pair.
  3. (Mg,Fe)SiO₃ in the ilmenite phase (PIL).
  4. (Mg,Fe)₂SiO₄ in the ringwoodite (spinel or gamma) phase (PGM)
  5. (Mg,Fe)O in the rocksalt phase (PMW).
  6. (Mg,Fe)SiO₃ in the garnet phase with Al substituting for an Mg-Si pair (PGT)

  The properties of the phases are given in a table. The variables correspond to the following:

  All values are the room pressure, temperature values

  1. Isothermal bulk modulus.
  2. (¶ K_T/¶ T)_p, GPa/K
  3. Volume per oxygen of phase cm³/mol per oxygen
  4. Coefficient a in thermal expansion = a + bT
  5. Coefficient b in this expression
  6. (¶ K_T/¶ P)_T,
  7. (¶ ²K_T/¶ T¶ P)
  8. Shear modulus, m , GPa
  9. ¶ m /¶ P
  10. ¶ m /¶ T
  11. ¶ Vol/¶ Fe
  12. Gamma, the Grunheissen parameter
  13. Q, the anharmonic parameter indicating the volume dependence of gamma
  14. ¶ Vol/¶ Al, see WW for details of definition
  15. ¶ K/¶ Al, see WW for details of definition
  16. ¶ m ,/¶ Al, see WW for details of definition

  These parameters are set at default values as defined by the paper WW. Users can change any of the values.

  Iterations indicates the total number of iterations or pressure steps for the calculation

  T is the foot temperature corresponding to depth of the starting pressure P. 17 GPa is set as the default which corresponds to the depth of 500 km.

  Output of Results

  The program calculates the stable phases at each P,T condition along an adiabatic temperature gradient, starting at ‘P’, ‘T’ for "Iterations’ steps of ‘DTAP’ in pressure. At each condition, it then calculates the composition of each phase using the data of WW and it calculates the volume per cents of each phase. Then it calculates the properties of the phases and finally calculates the properties of the bulk mineralogy. Output is graphical and tabular. The graphing output is versatile allowing the user to view any of the calculated variables as a function of depth. The output can be imported to a file in the users platform for further analysis.

  The opening screen of the program (data screen) contains the starting parameters from which the results will be generated.  Clicking the Run tr660 button begins the calculations, and loads the results screen (results 1), containing the graph.  At this point, the user may wish to resize the graph.

• Screen Shots
• The data screen: 1
• The results screens: 1 2 3
• Files
• Run the Program
  Note on running the program: Version 1.2 of the Java plugin is required for the program to execute properly. If the tr660 program fails to run, you can get version 1.2 of the plugin from Sun Microsystems, as part of the Java Runtime Environment, at java.sun.com/products/jdk/1.2/jre/index.html. Once you have dowloaded the plugin file, quit your browser, run the downloaded file, and follow all the instructions you are given to install it. After installation is complete, you should be able to run tr660. If you have any problems, please email Glenn Richard to report them.
• The source code
• The javadoc documentation of the source code
• Download a copy of the Program (85K JAR)
• Project Java
  tr660 was developed as part of Project Java, a program that provides computer science students at the State University of New York at Stony Brook with practical experience in software development.