Mn and S34 Partitioning in Sulphides a Comparison of Two Geothermometers

Abstract

<p>Sulphide samples from high and low temperature environments were used to compare two recently calibrated geothermometers: 1) The distribution of MnS between coexisting galena and sphalerite. 2) ThR fractionation of sulphur isotopes between coexisting sulphide minerals, The manganese analyses were done by two neutron activation procedures. For the high temperature environment, the MnS temperatures are significantly lower than the sulphur isotope temperatures; these results are reasonable if one accepts an hypothesis of limited subsolidus re-equilibratior of sulphur isotopes, but extensive redistribution of manganese. The sulphur isotope results for the low temperature deposit are also acceptable, but the manganese temperatures are too high, due to analytic errors (resulting from low concentrations and possible contamination), or to lack of equilibrium in the samples themselves.</p> <p>The extension of the sulphur isotope geothermometer to low temperatures (100-200°C) appears to be justified, whereas the results for the MnS geothermometer are inconclusive.</p>