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The low temperature end member has an isotopic composition that is typical of meteoric groundwaters being depleted in ^{18}O with respect to ocean water. We suggest that the range of minimum temperatures (30-50$^{\circ}$C) is characteristic of the depth of burial at the time of mineralization and that the near surface hydrogeology of the platform carbonates was dominated by meteoric recharge. With an elevated geothermal gradient of between 40 to 50$^{\circ}$C.km^{-1} this suggests that mineralization occurred at a depth of 0.8 to 1km. Such an estimate is in good agreement with previous studies (references).  The high temperature end member has a temperature greater than 100$^{\circ}$C and a $\delta$^{18}O value of +5‰_{VSMOW} that is typical of sedimentary basin and oil field brines (Sheppard, 1986). It is most probably sourced from depth within the Visean-Namurian shales of the Bowland-Hodder unit in the Edale Gulf. Likely minimum source depths lie between 2 to 3 km. An interesting comparison can be made between the derived formation water isotope composition of +5‰_{VSMOW} and that expected for a fluid in isotopic equilibrium at 100$^{\circ}$C with shales containing clay minerals. In Figure 7 we have replotted the data of Figure 6(d) and included the trajectory of evolution of pore waters in a shale assuming: (i) thesystem is closed i.e. the  pore waters are connate; connate and have an initial marine isotope composition of 0‰_{VSMOW};  (ii) the system eveolves under closed system conditions with a porosity of 20\%; (iii)  isotopic equilibrium is attained between the clay minerals and pore water, and; (iii) (iv)  the initial $\delta$^{18}O value of the kaolin in the shale is +20‰_{VSMOW}. The oxygen isotope fractionation factor for the kaolin-water system is taken from \citet{Sheppard:1996vq} \citet{Sheppard:1996vq}.  We are reassured that the derived fluid $\delta$^{18}O values are consistent with our understanding of the isotopic compositions of naturally occurring fluids and suggests that the clumped isotope temperatures are robust. For example were the calcite temperatures to have been as high as the maximum reported fluid inclusion homogenization temperatures of 240$^{\circ}$C then the derived fluid $\delta$^{18}O values would need to have been in excess of 18 - 20‰_{VSMOW}. Such values are in excess of any reported data for modern geothermal and formation waters \citep{Sheppard:1986ta}.