Experimental investigation of the metamorphism of siliceous dolomites III. Equilibrium data for the reaction: 1 Tremolite + 11 dolomite ⇌ 8 forsterite + 13 calcite + 9 CO2 +1H2O for the total pressures of 3,000 and 5,000 bars |
| |
| Authors: | Paul Metz |
| |
| Institution: | (1) Mineralogisch-Petrologisches Institut der Universität, Goldschmidtstr. 1, D-3400 Göttingen, Bundesrepublik Deutschland |
| |
| Abstract: | The temperature-X
CO
2-equilibrium data for the reaction 1 tremolite + 11 dolomite  8 forsterite + 13 calcite + 9 CO2 +1H2O have been determined at total pressures (P
CO
2 + P
H2O) of 3,000 and 5,000 bars. The results are shown in Figure 2 along with the data for the total pressure of 1,000 bars (Metz, 1967).The MgCO3 contents of the magnesian-calcites formed during the experiments agree very well with the calcite-dolomite-solvus which can be recalculated from Equation (1) and the activity coefficients for MgCO3 in magnesiancalcite as given by Gordon and Greenwood (1970).If the T-X
CO
2-equilibrium data are calculated from the equilibrium constant as given by Skippen (1974), assuming ideal mixing of CO2 and H2O, good agreement is achieved for the total pressure of 1,000 bars (see Figs. 4 and 5). At a total pressure of 3,000 bars, however, the calculated equilibrium temperatures are about 40 ° C below the experimentally determined values (see Fig. 6). This difference increases up to 70 ° C for a total pressure of 5,000 bars (see Fig. 7).From the experimentally determined equilibrium conditions of the assemblage: tremolite + dolomite + forsterite + magnesian calcite (see Fig. 8) the pressure of metamorphism can be estimated if the temperature is determined by the MgCO3-content of the magnesian-calcite from the calcite-dolomite solvus. However, when using the data of Figure 8, attention has to be drawn to the limiting condition of X
CO
2 0.2.Simplified reaction equation not considering solid solution in the carbonates |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
