Cleverley, James S., and Bastrakov, Evgeniy N. (2005) K2GWB: utility for generating thermodynamic data files for the geochemist's Workbench® at 0-1000 °C and 1-5000 °C bar from UT2K and the UNITHERM database. Computers & Geosciences, 31 (6). pp. 756-767.

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Abstract

The Geochemists Workbench® (GWB) is a versatile geochemical modelling software package capable of reaction path modelling, equilibrium fluid speciation and activity diagramming, although it is restricted by the availability of thermodynamic (log K) data files with a temperature range of 0-300 °C and pressures on the critical curve for water. The K2GWB (log K to GWB) utility is used to produce a usable Geochemists Workbench data file from a generic log K and system file generated by the UT2K utility complementing the UNITHERM thermodynamic database system. The GWB data files can be generated for pressure temperature conditions within the bounds of the modified Helgeson Kirkham Flowers model (0-1000 °C, 1-5000 bar). Data can be generated with any combination of pressure temperature log K grids required, allowing the Geochemists Workbench to be used to model a wide range of geological scenarios under polythermal and polybaric conditions, as well as the generation of activity diagrams over a wide range of pressures and temperatures. A comparative HCh and Geochemists Workbench model using the same thermodynamic dataset was run to benchmark test the validity of the new data files. Modelling the cooling of 2 molal NaCl-H2O fluid in equilibrium with a ganodiorite-type rock from 600 to 300 °C gave close to identical results between the two codes, validating the thermodynamic data conversion process described here. An investigation of the speciation of Au across a temperature pressure gradient from 550 °C and 1500 bar to 150 °C and saturated vapor curve pressures has been used to illustrate the usefulness of coupling thermodynamic data file generation at wide temperatures and pressures from a central database and the functionality of The Geochemists Workbench.

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