Experimental data base

For the extraction of the internally consistent data set (Gottschalk, 1997) a total of over 5300 experimental results (half brackets) for 253 different mineral reactions involving 94 rock-forming minerals and the fluid components H2O, CO2 and O2 were collected.

Virtually all experimental results were accepted with only minor restrictions. The following restrictions did apply.

For many solid solution series activity-composition relationships are not well known (e.g. Ganguly & Saxena, 1987); also considerable deviation from ideal mixing can be expected. Therefore experiments conducted with phases showing extensive solid solutions could not be used and were not considered any further. Equilibria involving a melt phase were neglected. Some restrictions were imposed on the P-T conditions.

Because of the limited P-T validity of the functions of state for H2O-CO2 mixtures, experimental results involving H2O and CO2 were restricted to the range of 350-1100°C and 50-2000 MPa. Up to 1000 MPa the function of state by Kerrick & Jacobs (1981) and above 1000 MPa the function of state by Belonoshko & Saxena (1992) was used.

If only pure fluids were involved in a reaction the results of experiments were considered down to 200°C using functions of state valid for these fluids (Shmulovich & Shmonov, 1975; Halbach & Chatterjee, 1982).

In the case that no fluid at all was involved, experiments up to 1500°C and 3000 MPa were included in the study. Experiments at higher pressures could not be considered because of insufficient knowledge concerning the pressure and temperature dependence of V° for solids.

last modified: 8.8.1997 by Matthias Gottschalk