Geochemistry of a fossil hydrothermal system at Barton Peninsula, King George Island

A fossil hydrothermal system on Barton Peninsula, King George Island, Antarctica, formed a series of lead-zinc- and pyrite + native sulphur-bearing epithermal quartz ± calcite veins, filling fault-related fractures in hydrothermally altered volcanic rocks of Eocene age. Equilibrium thermodynamic interpretation of mineral assemblages indicates that the deposition of native sulphur in the upper and central portions of the hydrothermal system was a result of the mixing of condensates of ascending magmatic gases and meteoric water. Sulphur isotope compositions indicate an igneous source of sulphur with a δ³⁴S_ΣS value near 0‰, probably the Noel Hill Granodiorite. Measured and calculated δ¹⁸O and δD values of the epithermal fluids indicate that local meteoric water played an important role for formation of lead-zinc and native sulphur-bearing quartz veins. -from Authors