Experimentelle Sideritbildung aus Calcit + FeCl2 |
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| Authors: | W Johannes |
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| Institution: | (1) Mineralogisch-Petrologisches Institut der Universität Göttingen, Deutschland |
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| Abstract: | The stability relations of calcite and siderite in the system Ca2+-Fe2+-CO
3
2–
Cl
2
2–
-H2O have been determined between 150 and 400° C in the pressure range from 250 to 2000 bars.It was found that the composition of the fluid phase coexisting with calcite and siderite is very poor in Fe2+ and correspondingly very rich in Ca2+ (see Tab. 1 and Fig. 3). The mole proportion Ca2+/(Ca2++Fe2+) exceeds the value 0.98 at temperatures below 250° C when fluid pressure is 1000 bars. The stability field of calcite narrows with decreasing temperature, increasing pressure, and decreasing concentration of dissolved salts (CaCl2++FeCl2). In our experiments siderite becomes unstable at about 400° C (see p. 158).The experimental data indicate that siderite will be formed by reaction of calcite with FeCl2-bearing solutions that have very low concentrations of Fe2+ as well as high Ca2+/(Ca2++Fe2+)-ratios. Solutions coexisting with calcite must be very poor in Fe2+, otherwise siderite is formed.
Herrn Prof. Dr. H. G. F. Wikkleb danke ich sehr für sein förderndes Interesse an dieser Arbeit und für eine kritische Durchsicht des Manuskriptes. Der Deutschen Forschungsgemeinschaft gebiihrt Dank für die Arbeitsmöglichkeit mit den Apparaturen, die Herrn Prof. Dr. Winkler zür Verfugung gestellt wurden. |
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