Fig. 1.
Plots of measured Mg vs. (A) CH4, (B) ΣCO2, (C) ΣHCOOH, and (D) ΣCO2 + ΣHCOOH concentrations for Von Damm vent fluids. Mg content is used as an indicator for seawater mixing; solid lines denote conservative dilution of the near-endmember composition (blue circles) with seawater (yellow stars), whereas dashed lines indicate species concentrations that result from nonconservative mixing in elevated Mg fluids (green symbols). Select δ13CCO2 values are plotted in B near corresponding samples. Uncertainties (2σ) not shown are smaller than symbols.