QUILF: A pascal program to assess equilibria among FeMgMnTi oxides, pyroxenes, olivine, and quartz
Computers & Geosciences
Al~traet--Program QUILF assesses equilibria among Ti-magnetite, ilmenite, augite, pigeonite, orthopyroxene, olivine, and quartz (or subassemblages thereof). Oxide and silicate equilibria are related through the QUIIF equilibrium: SiO 2 + 2Fe2TiO 4 = 2FeTiO 3 + Fe2SiO4 Quartz Ulvrspinel llmenite Fayalite. Depending on the assemblage, QUILF can provide information on temperature, pressure, oxygen fugacity, and the activities of SiO 2, TiO2, and Fe ° at which the phases were last in equilibrium.
... r many low-variance assemblages, the system is overdetermined; thus quantitative information can be extracted even if one phase is altered or has reequilibrated. QUIIF equilibria can reduce the uncertainties in temperature and oxygen fugacity as determined from coexisting ilmenite and Ti-magnetite alone. QUILF is written in Turbo Pascal for IBM PC and compatibles. The compiled program is approximately 210 kbyte; it also requires two data files that total approximately 10 kbyte. The compositions of the phases first must be projected into seven-component space (CaO MgO-MnO-FeO-Fe203 TiO2-SiO2) before they are used in program QUILF; routines to accomplish this are included in the program, and also are available as separate BASIC programs. Reaction between Fe-Ti oxides (Ti-magnetite and ilmenite solid solution) and ferromagnesian silicates can be expressed by the equilibrium: