The role of thermochemical sulfate reduction in the origin of Mississippi Valley‐type deposits. I. Experimental results

The kinetics of thermochemical sulfate reduction (TSR) were studied in experiments at 205–250°C, with determination of both sulfate and sulfide at intervals during the runs of up to 430 h. Analysis of the data indicates the reaction to have first-order kinetics, and extrapolating these data, plus data from the literature, to 150°C gives a range of possible rate constants from 100 to 10−4 year−1. Although the rate law has not been well established, a reasonable estimate allows calculation of the amount of sulfide ore formed as a function of flow conditions and time. It is here concluded that TSR could happen during the formation of Mississippi Valley-type ore deposits, subject to several caveats.