ABSTRACT

Sulfur and oxygen isotope ratios were determined for eight anhydrite samples (seven from silicate rocks and one from a marble) from the Iratsu peridotite-hornblendite-epidote amphibolite complex, central Shikoku, Japan. The δ³⁴S values of anhydrite are in the range from +4.7 to +11.0‰. The δ¹⁸O values of anhydrite from the silicate rocks are in the range from +8.6 to +10.2‰ and that from the marble is +12.4‰. The fairly uniform δ¹⁸O values may indicate that these anhydrites were re-equilibrated with respect to oxygen isotopes with host rocks during the Sambagawa metamorphism. The rather variable, high δ³⁴S values of anhydrite suggest that it is not cognate with the original rocks from which the host rocks were derived. The obtained δ³⁴S values do not provide a straightforward solution concerning the source of sulfur for these anhydrites.