A Windows Program for Feldspar group thermometers and hygrometers

Abstract

A Microsoft (R) Visual Basic software, called WinFeldth, has been developed for plagioclase, alkali feldspar and liquid compositions that coexisting as two-feldspar, plagioclase-liquid and alkali feldspar-liquid pairs to calculate the temperature (T, degrees C) and water contents (H2O wt%) of igneous rocks. The program allows the users to enter major oxide of each plagioclase and alkali feldspar data and liquid compositions. Alternatively, 10 input variables such as the mole fractions of X-Ab(PF), X-Or(PF), X-An(PF), X-Cn(PF), X-Ab(AF), X-Or(Ar), X-An(AF), X-Cn(AF) as well as pressure (P, kbar) and temperature (T, degrees C) can be entered to estimate two-feldspar thermometers on the basis of thermodynamic modelling of ternary solid solutions and pressure- and temperature-dependent equations, respectively. WinFeldth enables the users to enter and load multiple two-feldspar and liquid analyses in the program's data entry section. Alternatively, the composition of analyses can be typed in a blank Excel file (i.e., WinPAL.xlsx) and then loaded into the program's data entry screen for data processing. Representative two-feldspar analyses are calculated based on 8 or optionally 32 oxygens by the program. WinFeldth evaluates eleven two-feldspar thermometers, nine two-feldspar thermometers based on the thermodynamic modelling of ternary solid solutions, six plagioclase-liquid thermometers, two alkali feldspar-liquid thermometers, five plagioclase-liquid hygrometers, one alkali feldspar-liquid hygrometer and plagioclase-liquid barometer. This program generates and stores all the calculated results in the Microsoft Excel file (i.e., Output.xlsx), which can be displayed and processed by any other software for further data presentation and graphing purposes. The compiled program code is distributed as a self-extracting setup file, including a help file (i.e., WinFeldth.chm), test data files and various graphic files for binary and ternary plots, which are intended to produce a high-quality printout.