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A characteristic feature of systems with episodic pulsing of warm to hot fluid is the development of a thermal anomaly along the high permeability paths in which flow is focused. An example is the perturbation of the temperature field observed in Mississippi Valley Type (MVT) districts that lie around the upper Mississippi Valley and other major Palaeozoic sediment basins in the continental USA \citep{Sangster:1994ub}. Similar temperature anomalies have been reported for other sedimentary basins, for example to the south east of the Massif Central in France \citep{Charef:1988vt}. The anomaly is seen as a difference between the temperature of precipitation of hydrothermal minerals and that of the of the host rock at the depth of burial and time that the mineralization took place. Using simple thermal modelling Cathles and co-workers show that that the temperature difference is due to heat advection associated with episodic, rapid release of hot fluids from deeper regions of the basins \citep{Cathles:1983tj,CathlesIII:2005uo}. In these example the fluids are thought to originate from overpressured brines in compacting sedimentary basins. Importantly, the fluid velocities required to produce the thermal anomaly are more than 1000 times greater than could be produced by the steady subsidence, compaction, and dewatering of the basins \citep{Cathles:1983tj}. This suggests to us that the pulses result from a coupling between the pore fluid pressure and rock failure. We envisage that when pore fluid pressures approach lithostatic either mode I hydraulic fracturing or shear failure and development of dilation jogs along fault surfaces allows rapid dewatering of the sediment pile with channelled flow of fluids.   To better understand these processes we have used clumped isotope thermometry to determine the temperature at which hydrothermal vein calcite precipitated in dilation voids of a Variscan strike-slip fault in the southern Pennines of the United Kingdom. The veins are associated with Pb-Zn and fluorite mineralization and in the past the fault, and other areas of the southern Pennines have been extensively worked as an economic deposit. Whilst on a different scale it has been suggested that the Pb-Zn mineralization has close affinities with the classic MVT deposits of North America. The fault, located on the margin of a lower Carboniferous platform on which shelf carbonates were deposited, separates the platform from a half-graben basin filled with deep water facies limestones and shales of lower to upper Carboniferous age. Previous workers have suggested that the faults bordering the platform provided a network of high permeability channels for the mineralizing fluids \citep{Quirk:1991uq, Kendrick:2002vc, Frazer:2014eh} Frazer:2014eh}.  Clumped isotope geothermometry relies on the fact that the heavy isotopes ^{13}C and ^{18}O are ordered in the carbonate lattice with the degree of ordering being an inverse function of temperature. 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. As temperature increases the isotopes tend towards a more random or stochastic distribution. 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. This is analogous to the concept of a closure temperature for radiogenic isotopes or cation ordering in minerals. In this study this temperature is taken as the precipitation temperature of the calcite. 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 we can use published fractionation factor calibrations to calculate the isotopic composition of the parent fluid. Using these techniques we find:  (i) the calcite precipitated at temperatures between 40° and 100°C.