The Earth's thermal field on the tertiary of Poland
The paper discusses the correlation between the elements of the Earth’s thermal field (temperature T, gradient T = G, heat flow Q) and the principal tectonic provinces on the territory of Poland. With this object in view, a map of temperature gradient distribution for the interwals 200-2000 m (Fig. 1), a map of geoisotherms for depths of 1 km (Fig. 2) and 2 km (Fig. 8 ), and the values of heat flow from the northern part of the Polish Lowland (Fig. 7) were analysed. The values of temperature gradients as well as those of temperature for a depth of 1 km are given in Figs. 1 and 2. Fig. 3 shows the values of heat flow for Central Europe. Zones of low values of Q (Q, < C 1.30 [mikro]cal/cm2 s) were distinguished. Table 1 gives new estimates of the density of the Earth’s surface heat flow. In Figs. 3 and 4, respectively, thermograms from East European Platform and south-eastern Poland are shown. An analysis of the data obtained indicates the following regularities: 1. A general change of the elements of thermal field in the direction NW-SE is disturbed by a W-E zone appearing in the area of the stable Precambrian platform, characterized by increased Q, T and G values. The author is of the opinion that this phenomenon is caused by a deep fault. 2. The second zone of higher than mean, “cratonic” Q values is the area north-west of Rawa Ruska. 3. G and Q values for south-eastern Poland do not exceed mean values, typical for Precambrian platforms, and are in general characteristic of the whole craton of East Europe as far as the Ural Mountains. 4. The values from south-western Poland and the area of Upper Silesian Basin are typical for regions of Hercynian orogeny. Thermal field analyses were performed basing on the relations, generalized by statistical analysis, between the elements of thermal field in different tectonic provinces (Fig. 5). It should be noted that there is no relation between the value of heat flow and the thickness of platform sedimentary cover (Fig. 6 ).
