Heat flow, radiogenic heat production and crustal temperatures in England and Wales

Abstract

New values of heat flow are reported from thirty-one sites in England and Wales. Thermal conductivity of core material from fourteen of the sites and thermal gradients, obtained over several hundred metres, were used to calculate reliable heat flow values for these localities. At the remaining seventeen sites the value of heat flow is calculated from thermal gradient measurements alone, assigning conductivity on the basis of stratigraphic logs. An average heat flow of 1.40 μcal/cm 2 s is computed for the region, based upon 40 sites. Slightly higher than average heat flow may characterise the Lincolnshire sedimentary basin, within which temperatures may reach 100°C at about 3 km depth. Surface heat flow is linearly correlated with heat production in local granitic or low-grade metasedimentary basement encountered in ten boreholes. The intercept of the dependence is 0.56±0.07 μcal/cm 2 s; and the high slope, 16.0±1.6 km compared with 5–11 km reported for other areas, is held to reflect the nature of late Precambrian, Lower and Upper Palaeozoic tectonic events in the region.