Jonathon MacDonald HBSc thesis abstract

Hogarth Pit Lake was formed from the continual flooding of the open pit iron mine at Steep Rock Lake near Atikokan, Ontario, Canada.  In the past Hogarth Pit Lake has been toxic to aquatic species, although recent studies are beginning to show that toxicity is no longer a problem.  It was the purpose of this stuffy to relate the sources of the Hogarth Pit Lake waters to the surrounding geological units.  To further the study potential sulphate sources were investigated for any sulphides present in the rock units that may lead to high sulphate levels through oxidation.  Water-rock reactions such as carbonate buffering reactions were used to aid in determining potential sulphide sources producing high sulphate levels through oxidation.  Carbon and sulphur isotope abundances of surrounding rocks and water were another tool used to further aid in determining sulphate sources.  Tributaries from the hangingwall and footwall display a wide range in trace element and stable carbon and sulphur isotope composition.  δ³⁴S water values as low as -3.6€ indicate sulphide oxidation which matches δ³⁴S depleted rock values (>-7.2€).  Water samples show depletions up to -20.3€  δ¹³C while the lowest rock sample is only -4.0€  δ¹³C.  The investigations carried out isolated they pyritic rich Ore Zone as a sulphate source that leads to high sulphate waters by a groundwater source.