Stable oxygen isotope ratios of pore waters from ODP Leg 166 sites

These pore waters generally show a positive correlation between d18O and the concentration of chloride. The exception to this trend is Site 1006, where the pore waters exhibit nonlinear behavior with respect to chloride.

The correlation between the concentration of Cl- and d18O at most of the sites appears to be a coincidence because although the increase in Cl- is a result of diffusion from an underlying source, the increases in d18O result from the recrystallization of metastable carbonates in the presence of a geothermal gradient. The difference in behavior in the d18O of the pore water at Site 1006 is probably a result of the relative reduced rate of carbonate recrystallization at this site.