Early subsurface temperature measurements in the Netherlands

Abstract

The earliest known subsurface temperatures were obtained in 1879 in a borehole (to in the a depth of 365 m) centre of the city of Utrecht. During the years 1912 - 1914 temperatures were measured to depths as great as 1400 m in a number of wells in structurally high areas in Tertiary, Senonian, Triassic, Upper Permian and Carboniferous rocks. In 1952 additional data were obtained (Peel horst), followed in 1956 by a few measurements in the South Limburg mining district. The various thermometers used are briefly described. The temperatures are related to lithology and stratigraphy and to the salinities of the interstitial waters. very low geothermal gradients are present in Quaternary to uppermost Tertiary due to percolating waters of meteoric origin. In the post-carboniferous overburden and, where shallow, in the higher parts of the Westphalian the waters are either fresh, or, if saline, do not reach sea-water concentrations. In such areas the geothermal gradients are lower than 3°C/100 m. In the Carboniferous, due to the low thermal conductivity of coal, gradients tend to be high: over 4, and reaching 5.2 to 5.6°C/100 m. In contrast, the high conductivities of anhydrite and rock salt cause low gradients (2.5 in the Buntsandstein and Zechstein formations).