Sulfide mineralogy, sulphur content and sulphur isotope composition of mafic and ultramafic rocks from leg 147

A total of 107 hard-rock samples from Ocean Drilling Program Leg 147 drill cores were analyzed for sulfur content and, where possible, for sulfur isotope composition and sulfide mineralogy. At Site 894, plutonic rocks (gabbros and gabbronorites)from the roof of an intrarift magma chamber were sampled, whereas mafic and ultramafic rocks (gabbroic rocks, troctolites, dunites, and harzburgites) belonging to a transition zone between the lower magmatic crust and upper residual mantle were sampled at Site 895. The average (and range) of sulfur content in analyzed rocks are as follows: gabbros (14 samples): 1590 ppm (< 100-10340 ppm); gabbronorites (39 samples): 760 ppm (<100-3100 ppm); troctolites (9 samples): 680 ppm (<100-1700 ppm); harzburgites (20 samples): 200 ppm (<100-700 ppm); and dunites (19 samples): 400 ppm (