ABSTRACT

If some of the strata-bound sulfide ores result from deposition on the seafloor through submarine volcanic activity, it seems probable that the isotopic exchange reaction takes place between seawater sulfate and volcanically derived sulfur compounds, at least to some extent. Since the amount of sulfur from seawater would normally be much larger than that from volcanic source, it is expected that the isotopic compositions of sulfur-bearing species in this system are largely controlled by the seawater sulfate. A remarkable parallelism observed between sulfur isotopic compositions of ancient seawater sulfate and the strata-bound sulfide deposits of volcanic association throughout geologic time (SANGSTER, 1968) may most reasonably be explained with this hypothesis.