Figure 2: Modelling of δ66Zn evolution in slab fluids and residual serpentinites for the sulfate- and sulfide-bearing fluid scenarios.
From: Zinc isotope evidence for sulfate-rich fluid transfer across subduction zones
Evolution of residual serpentinite δ66Zn (in black) and that of associated fluids (in light blue) with the remaining fraction of Zn in the rock (F) using batch and Rayleigh distillation models. The models were performed at 300 °C (a,d,g), 450 °C (b,e,h) and 600 °C (c,f,i). The models were performed using fractionation at equilibrium fractionation factors, a,b,c: between Zn contained in the serpentinite sulfides (ZnHS2(H2O)4) and a sulfate-rich fluid (ZnSO4(H2O)4). d,e,f: between Zn contained in the serpentinite phyllosilicates (Zn(H2O)6) and a sulfate-rich fluid (ZnSO4(H2O)4) and g,h,i: between Zn contained in the serpentinite phyllosilicates (Zn(H2O)6) and a sulfide-rich fluid (ZnHS2(H2O)4). The fate of Zn in the rock sulfides is not reported as there is no fractionation at equilibrium with only one species in solution (ZnHS2(H2O)4). The solid coloured areas represent the range of δ66Zn in measured samples for antigorite Alpine serpentinites (in red), and fluid-derived material (in yellow: atg/ol2-serpentinites and in orange: Kohistan olivines Kol). The grid represents the range of possible fluid compositions from the initial starting composition (black star) to the end of the antigorite field, defined by the observed range of δ66Zn in the samples (in red). Fractionation factors from Black et al. and Fujii et al.2,14. The model is fully described in the method.
