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Abstract:
Ten thermal springs occur in seven centres in Derbyshire, England, with temperatures up to 27.5 {degrees}C compared with an ambient groundwater temperature of about 9 {degrees}C. The springs discharge from a karstic Dinantian limestone aquifer along the boundary with the overlying Namurian strata around the edge of a regional dome structure. The water is heated by deep circulation to as much as 1 km, with the hottest spring being at Buxton spring, where the water is 5000 years old. A comparison of flow data from the Buxton spring with groundwater hydrographs shows seasonality in the thermal flows, suggesting that the loading effects produced by recharge are transmitted through this deep aquifer system. From a review of the geological history and the hydrogeology and the use of measurements on the Buxton spring it is suggested that the thermal flow system may have its roots in ancient convection cells possibly established in the deeply buried aquifer in late Carboniferous-Early Permian times. Subaerial erosion during the Pliocene removed the impermeable cap rocks and allowed both the thermally heated water to form warm springs and this deep groundwater circulation to be recharged by meteoric waters. The location of the individual springs is likely to date from the downcutting during the Late Pleistocene that formed the modern river valley topography