Figure 9
Pressure-temperature diagrams showing calculated trapping conditions for type 2b fluid inclusions in sample Dior-2 (A) and type 2a fluid inclusions in samples Gran-1b and Slate-1a (B). (A): The solid lines marked 1 and 2 (in white circles) represent P-T conditions at saturation (CH4-rich fluid) for type 2b fluid inclusions with salinities of 18 and 24 wt.% eq. NaCl, respectively. The heavy long-dashed line represent the average isochore of type 1 fluid inclusions occurring in sample Dior-2, and the short-dashed lines form the ± 1σ envelope of the average isochore. Stars indicate the maximum P-T conditions of equilibration of calc-silicate layers from the Thetford Mines ophiolite calculated by Laird et al. [50]. Because quartz is absent from their reported assemblage, the actual conditions should plot at lower temperatures and pressures along the univariant reaction 5Pumpellyite = 5Zoisite + 2Prehnite + 2Grossular + Chlorite + 9H2O which approximately parallels the isochores. (B): The grey shaded area represents the calculated trapping conditions for fluid inclusions in granite sample Gran-1b. The filled dot represents the calculated total homogenization conditions for a representative fluid inclusion in rodingitized slate sample Slate-1a. The solid line connected to the filled dot represents the calculated isochore of the corresponding fluid inclusion. Dashed lines represent isochores of type 1 fluid inclusions in sample Slate-1a. The occurrence of prehnite that formed contemporaneously with other calc-silicates in the studied rodingitized dykes and slate imposes the limit on homogenization pressures.