SUMMARY

This investigation can be summarized as follows:

1. The common presence of troilite throughout the entire section that was sampled during both Legs 118 and 176 indicates that much of the sulfide assemblage from Hole 735B precipitated from a magmatic system and subsequently underwent low-temperature reequilibration.
2. The only interval where troilite was not identified is the intensely foliated and metamorphosed upper 150 m of the section (0-150 mbsf). Although the available thin section suite from this part of the section is incomplete, armored, globular sulfides were exceedingly rare.
3. Troilite is present with both Fe-rich and Fe-poor pyrrhotite compositions but does not occur in this sample suite unless pyrrhotite, chalcopyrite, and pentlandite are also present. Samples with only pyrrhotite or pyrite do not contain troilite.
4. The combined effects of olivine accumulation in troctolites and high pentlandite to pyrrhotite ratios accounts for the sporadically high bulk-rock Ni compositions.
5. The lower variability of Ni and Cu bulk-rock compositions between 960 and 1170 mbsf and the coincidence of the lower part of this interval with a change in pyrrhotite composition, a sharp decrease in magmatic foliation, and a sharp decrease in magnetic susceptibility suggest a different magma batch below and above.
6. The Co/Ni value of the sulfides examined in this study suggests that they were formed in a magmatic Fe-Ti oxide or magmatic immiscible sulfide Ni-Fe-Cu system. The reader should note, however, that the sample suite for this study was heavily biased away from oxide-bearing intervals, and the sulfides in the oxide-bearing intervals may have a completely different composition and paragenesis.
7. PGE concentrations are low in all samples investigated, with a background value of <0.4 ppb. Rare samples have elevated values, but there is no evident commonality in occurrence. The highest values analyzed are from a thin sulfide-bearing clinopyroxenite near the bottom of the section.