Geochemistry and Stable Isotope Composition of Hogarth and Caland Pit Lakes, Steep Rock Iron Mine, Northwestern Ontario, Canada

摘要

Caland and Hogarth pit lakes were formed after the closure and subsequent flooding of the Steep Rock iron mines, Ontario, Canada. The oxygen and deuterium isotopic composition of the pit waters define a linear trend consistent with non-equilibrium evaporation. The sulfur isotope composition of dissolved sulfate is similar for the two pit lakes and indicates derivation from pyritic lenses within the ore zone. The δ~(18)O for dissolved sulfate indicates different mechanisms for pyrite oxidation. For Hogarth, sulfate is produced by anaerobic oxidation of pyrite by ground water;;whereas Caland sulfate is produced by aerobic oxidation of pyrite by ground water. The carbon isotopic composition of DIC from Hogarth is similar to that isotopic composition of the carbonate wall rocks;;whereas, DIC in Caland pit water is isotopically depleted due to exchange with DOC generated by fish farming activities.