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\subsection{Temperature}  The data for the temperature at which calcite precipitated at Dirtlow Rake are the first measurements made for the southern Pennines using the clumped isotope technique. They show that temperatures varied during vein growth between lower and upper limits of 30 to 100$^{\circ}$C. As seen in Figure 5 these temperature variations are episodic, representing periods during which the temperature evolved followed by sharp breaks in the temperature trends. It is relevant to ask if these temperatures are robust and representative of the likely hydrothermal fluid temperatures. The most direct comparison we can make is with fluid inclusion homogenization temperatures. Hollis and Walkden (2002) report a mean temperature of 154$^{\circ}$C with a large range of between 100 and 200$^{\circ}$C for inclusions in zone 4 calcites sampled from the northern margin of the Derbyshire platform. Higher maximum temperatures and a greater temperature range have been reported by Kendrick et al. (2002) for fluorites from Hucklow Edge, a mineralized vein within 10km of Dirtlow Rake (T_{max}=240$^{\circ}$C, range = 90-240$^{\circ}$C). These authors exclude temperatures as high as 300$^{\circ}$C suggesting the data are compromised by stretchingof  and fluid loss from the inclusions. All these temperatures are significantly higher than the temperature range we report for DLR7 and higher than any temperatures we have recorded elsewhere in the Peak District (unpublished data). The high maxima and large range of temperatures reported by Hollis and Walkden (2002) and Kendrick et al. (2002) are hard to reconcile with the clumped isotope data. They are also hard to understand in relation to current basin evolution models for the Edale Gulf (Colman, 1989, Walkden and Williams, 1991) which suggest maximum depths of burial of five to six km. To achieve temperatures of 240$^{\circ}$C would require geothermal gradients of more than 40$^{\circ}$C.km^{-1}. A possible explanation for the discrepancy between clumped isotope and fluid inclusion homogenization temperatures is that the inclusions are gas rich. Gas rich inclusions have been reported from carbonate phases from MVT districts \citep{Jones_1992}. Homogenization of gas rich inclusions will occur at higher temperatures than for a pure water inclusion. In contrast the clumped isotope temperature data is in good agreement with several other fluid inclusion studies. For example Atkinson (1983) reported homogenization temperatures for type 2 (62$^{\circ}$-82$^{\circ}$C), type 3 (64.9$^{\circ}$-98.9$^{\circ}$C), type 4 (63.4$^{\circ}$-106$^{\circ}$C) and type 5 (66.3$^{\circ}$-68.3$^{\circ}$C) inclusions in fluorite. Type 1 inclusions have a higher homogenization temperatures of 119.5$^{\circ}$ - 157$^{\circ}$C.