Heat flow, heat production and thermo-tectonic setting in mainland UK

Abstract

New heat flow data for the United Kingdom, together with additional heat flow and heat production determinations for Caledonian-age granites, have led to a revision of the UK heat flow map and a re-examination of the relationship between heat flow ( q 0 ) and heat production ( A 0 ) for granites and basement rocks. Previously recognized broad belts of above-average heat flow are now resolved into separate zones which reflect, to a greater extent, the geological structure and tectonic history of the UK. The zones of highest heat flow are spatially associated with voluminous, high heat production granitoid batholiths in SW England, northern England and the Eastern Highlands of Scotland. A single linear correlation between q 0 and A 0 is no longer tenable and an analysis in terms of broad heat flow provinces, each with a characteristic upper-crustal heat production distribution and deep heat flow contribution, is also considered to be an oversimplification. On the q 0 –A 0 plot, the data form four separate clusters; three corresponding to the granite batholiths in SW England, northern England and the Eastern Highlands of Scotland, and the fourth to the basement rocks of central England and Wales. An explanation of the q 0 –A 0 data is proposed in terms of the crustal structure and thermo-tectonic setting of each area. In the case of the granite batholiths the data reflect the contrasting depth extent and radioelement-depth functions of the intrusions. These parameters in turn are related to the magmatic evolution and emplacement history of each batholith and the nature of the crust into which they were emplaced.

The Cornubian geothermal province: heat production and flow in SW England: estimates from boreholes and airborne gamma-ray measurements

“…For the shallow boreholes (depth 100 m), the correction ranges from 27.4 to 24.2 mW m . Compared to the heat flows reported by Lee (1986) and Lee et al (1987), which were only corrected for the effects of recent climate in boreholes less than 200 m deep, there is an increase in all values ranging from 2.8 mW m −2 at Tregarden Farm to 17.1 mW m −2 at Polgear Beacon.…”

“…Heat flow estimates, as originally reported by Lee (1986) and Lee et al (1987), are listed as HF (Lee 1986) and were corrected for recent climate change and topography. The revised heat flow estimates (HF REV) from this study are compiled from a newly calculated Raw HF, a full palaeoclimate correction and a topographic correction from Wheildon et al (1981).…”

“…In accordance with Lee et al (1987), it is assumed that there is constant heat production with depth, in which case f(z) in Eq. (4) has the form:…”

“…The potential of geothermal energy systems in the UK was subsequently reviewed by Downing and Gray (1986a, b) and later by Lee et al (1987) and Barker et al (2000). The reviews and studies discuss low enthalpy systems in Upper Palaeozoic aquifers and thermal springs together with Mesozoic basins.…”

“…These data were supplemented by measurements in mines at South Crofty and Geevor, where access to much greater depths was possible (Tammemagi and Wheildon 1974). These combined results were published in summaries of the UK heat flow (Lee 1986;Lee et al 1987) and it is these publications which have been widely cited when referencing these data. However, as reported by Lee (1986) and Lee et al (1987) only a correction for recent climate change was applied, and this was only for boreholes less than 200 m deep, despite the fact that Wheildon et al (1981) had undertaken a full palaeoclimate correction.…”