39. PRELIMINARY RESULTS OF SULFUR ISOTOPE INVESTIGATIONS ON DEEP SEA DRILLING PROJECT CORES FROM

Thirty-five sulfur isotope determinations were conducted on basalts and sediments from the DSDP Legs 52 and 53. Using a combined mechanical and chemical preparation, it was possible to investigate different sulfur species in the basalts. Sulfides occurring in globules reflect the isotopic value of mantle sulfur, with a mean of — O.6°/oo. The "sulfate " sulfur of the basalts (including pyrite sulfur) shows a wide spread from —9.6 to +lθ.7°/oo. "Sulfate " sulfur reflects sensitively secondary influences as sea water alteration or low-temperature hydrothermal activity. Pyrites separated from the basalts are close to the mantle value. Pyrites isolated from sediment cores from Hole 418B are enriched in 32S ranging from-37.2 to- 4 8. l ‰