Heat refraction and heat production in and around granite plutons in north-east England

Abstract

The country has both salt springs and hot springs, and the waters flowing from them provide hot baths, in which the people bathe separately according to age and sex. As Saint Basil says: "Water receives heat when it flows over certain metals,and becomes hot, and even scalding".'Bede, A History of the English a u r c h and People, 7 3 1. SummaryExisting surface heat flow determinations in north-east England indicate a difference in thermal structure between the Alston block of the North Pennines and the coastal regions. New heat flow determinations in the Askrigg block and on the coast support the original indications of higher heat flow in the positive blocks, which are underlain by 400 Myr old granites, than in their marginal sedimentary troughs along the present coastline. Although the two blocks are geophysically and geologically similar, surface heat flow in the Alston block is 30mWm-' higher than it is in the Askrigg block 50km to its south. Heat flow refraction around high conductivity plutons with high heat production may significantly affect the interpretation of heat flow measurements made on a regional scale but in the present case its effect, if any, is to emphasize the heat flow difference between the two otherwise similar blocks. The chemical differences between the Wensleydale and the Weardale granitescupolas of the granites underlying the Askrigg and Alston blocks respectivelymay be representative of the granites as a whole and the difference in surface heat flows may result from' a contrast in radiogenic heat production between the two granites extending to mid-crustal depths.

Accounting for palaeoclimate and topography: A rigorous approach to correction of the British geothermal dataset

“…Hitherto, the definitive analysis of the geothermics of this borehole is again arguably that by England et al (1980). They determined that the best estimate of the heat flow came from the deeper part of the borehole within the Wensleydale granite, but did not specify the depth range of measurement.…”

“…The Rookhope borehole (at NY 938 428) was the first to penetrate the Palaeozoic Weardale Granite that underlies most of County Durham in northeast England; the heat flow in this borehole has been extensively studied (e.g., Bott et al, 1972;England et al, 1980). Hitherto, the definitive analysis of the geothermics of this borehole is arguably that by England et al (1980).…”

The resolution of past heat flow in sedimentary basins from non-linear inversion of geochemical data: the smoothest model approach, with synthetic examples

“…It is commonly assumed that the most significant heat transfer occurs in a vertical direction, justified in the absence of rapid horizontal fluid flow (Bethke 1985;D e Bredhoeft, Djevanshir & Belitz 1988) or major lateral discontinuities in thermal properties (England, Oxburgh & Richardson 1980). Additional assumptions are that a steady state approximation is appropriate and that heat flow is independent of depth.…”

Horizontal heat transfer due to radioactivity contrasts: causes and consequences of the linear heat flow relation

“…England, Oxburgh & Richardson (1980) have recently questioned the validity of this assumption. Most studies available on the subject of lateral heat transport deal with the effects of thermal conductivity contrasts (Lachenbruch & Marshall 1966;Lee & Henyey 1974;Lee 1975).…”

“…Simmons (1 967) calculated the heat flow anomalies created by bodies of different sizes and shapes. England et al (1980) carried out an extensive study of the effects of both conductivity and radioactivity contrasts for an isolated pluton, and found that the latter act to reduce depth-scale D. Both papers are confined to the case of an isolated body with uniform heat production, whereas the distribution of radioactivity is typically more complex.…”