Hydrothermal pyrite samples from Holes 477, 477A, and 478 have sulfur isotope values ranging from about 10 to 11 per mil. Samples with negative sulfur isotope values generally have low sulfide sulfur contents and reflect mixed bacterial and hydrothermal sulfur sources. At higher sulfur contents, the hydrothermal component predominates, producing positive isotope values. Hydrothermal sulfide derives from reduction of seawater sulfate and may contain a significant basaltic component. Hydrothermal anhydrite is restricted to a narrow zone beneath a dolerite sill at Site 477 and, because of partial sulfate reduction in the circulating waters, has isotopic values (23.5-25 per mil), heavier than seawater.

Empty cells = not determined.

Supplement to: Shanks, Wayne C; Niemitz, Jeffrey W (1982): Sulfur isotope studies of hydrothermal anhydrite and pyrite, Deep Sea Drilling Project Leg 64, Guaymas Basin, Gulf of California. In: Curray, JR; Moore, DG; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 64, 1137-1142