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Mineralization with MVT affinities occurs in the Peak District area of the southern Pennines in the UK. Here strata bound deposits (flats) of dominantly Pb-Zn and fluorite mineralization are closely associated with near vertical veins (scrins) that lie along strike-slip fault surfaces and fractures of Variscan age \citep{Quirk:1991uq}. As with the upper Mississippi valley sedimentary basins it is widely held that the mineralization results from basin scale migration of sedimentary formation waters \citep{ixer1993lead}. However, the driving force for, and rates of fluid migration are poorly constrained. Opinion ranges from slow gravity driven flow as a result of tectonic uplift associated with the Variscan inversion \citep{Quirk:1991uq} to a seismic valve type process with rapid dewatering of the over-pressured basin fill triggered by fault activity \citep{Frazer:2014eh}. Evidence for a thermal anomaly associated with rapid advection of fluids is not conclusive. Fluid inclusion homogenization temperatures span a wide range from <70$^{\circ}$ to >240$^{\circ}$C \citep{Atkinson:1983ua, Kendrick:2002vc}. Mineralization is thought to have occurred at depths between 1 and 2km \citep{Colman:1989vf}. Thus, assuming a geothermal gradient of 30$^{\circ}$C.km^{-1}, the fluid inclusion homogenization temperatures are at, or greater than the maximum expected host rock temperature at the time of mineralization. This suggests that fluid movement was rapid and therefore unlikely to be associated with slow, gravity driven flow or a gradual dewatering of the basin fill. There are questions, however, as to the reliability of some of the reported temperatures that are derived from fluid inclusion analysis. It is difficult to envisage how the very high temperatures of >240$^{\circ}$C or more are generated in sedimentary basins with maximum depths on the order of four to five km. In addition Kendrick and co-workers report evidence of stretching, necking down and leakage in samples that show anomalously high temperatures \citep{Kendrick:2002vc}.   To better understand the possible coupling between faulting and fluid flow in the Peak District we have used clumped isotope thermometry to determine the temperature at which a Variscan hydrothermal calcite vein precipitated. Clumped isotope thermometry is based on the fact that the rare, heavy isotopes of carbon (^{13}C) and oxygen (^{18}O) are ordered in the carbonate lattice. This is a result of the greater stability of the ^{13}C-^{18}O bond compared to bonds involving either no, or a single isotopic substitution. The degree of ordering is an inverse function of temperature. As temperature increases the isotopes tend towards a more random or stochastic distribution \citep{Eiler:2007vua}. Measurement of the degree of ordering allows us to estimate the temperature at which the distribution of isotopes in the calcite structure are locked in \citep{Ghosh:2006cn}. This is analogous to the concept of a closure temperature for radiogenic isotopes or for cation ordering in minerals. A key advantage of the method is that the temperature estimate is based on the distribution of carbon and oxygen isotopes within a single phase and not on the partitioning of oxygen isotopes between calcite and it’s parent fluid as in the conventional oxygen isotope geothermometer. Thus combining the clumped isotope temperature (T($\Delta$_{47})) with the bulk oxygen isotope composition of the carbonate represented by it's $\delta^{13}$C value we can constrain the isotopic composition of the parent fluid. Using these techniques we find:\enumerate find:  {(i) the calcite precipitated at temperatures between 40° and 100°C.  (ii) the parent fluids range in isotopic composition from -4‰_{VSMOW} to +5‰_{VSMOW} and represent mixtures of a cool, meteoric water and a more evolved formation water.  (ii) (iii)  the temperature at which the calcite precipitated is a conservative tracer for the fluid mixing. This implies that heat is rapidly advected as the hydrothermal fluid flow is focussed along the fault plane. (iii) (iv)  The calcites exhibit zoned development characterised by cyclic and pulsed evolution of precipitation temperatures and fluid compositions as a result of varying mixing ratios of the two fluid end-members. (iv) (v)  The fluids have evolved under low fluid:rock ratios.}