Figure 9

Sulfur isotope compositions of pore fluids and free gas samples. (a) Frequency distribution of δ³⁴S values for sulfide (green) and sulfate (blue) collected from Palaeochori Bay, Milos (this study). The vertical solid line is the average of free gas sulfide in Palaeochori Bay (δ³⁴S = 2.5‰) and the width of the line is the standard deviation of all measurements (±0.28‰, n = 4). The dashed vertical line represents seawater sulfate (δ³⁴S = 21.2‰). (b) Frequency distribution of free gas sulfide δ³⁴S at Nisyros Island [30]. Note, the δ³⁴S values for this study (a) were normalized to VCDT and the literature values (b) were referenced to CDT.