Crustal heat production and mantle heat flow in Central and Eastern Europe

Abstract

The conversion of seismic velocity ( υ p ) into radiogenic heat production ( A) enables the distribution of crustal heat sources to be estimated. This technique was used to assess the mantle (Moho) heat flow for 49 seismic velocity-depth profiles located along five continental traverses in Central and Eastern Europe. The effect of pressure and temperature on υ p was taken into account, as was the age dependence of A. The uppermost part of the crust is dominated by microcracks that may have allowed a certain redistribution of radioactive elements by deep groundwater migration. Furthermore, owing to the highly variable value of the pressure derivative of v p in the uppermost crust, the use of a A−υ p relationship is problematic within this depth range. This radioactivity enriched zone, the thickness of which can be determined from the parameters of the heat flow-heat production relationship, was therefore treated separately. According to the model adopted for the upper crust, the Moho heat flow ranges from 14 to 26 mW m −2 in the stable continental areas such as the shields or ancient platforms. Younger terrains are characterized by elevated Moho heat flows of 20 to 40 mW m −2 and the Moho heat flow may eventually attain values over 50 mW m −2 in regions characterized by very high surface heat flow, such as the Pannonian Basin for example. The present data were compared with crustal models proposed by other authors. Moho heat flow estimates based on a simple exponential distribution of heat sources valid for the whole crust might be too high if applied to stable continental crust. Our data confirm a considerable variability in the mantle heat flow corresponding to the large-scale tectonothermal evolution, with a generally lower Moho heat flow typical of consolidated stable continental crust. The discrepancy in relation to the above estimates can be accounted for by a heat generation hump beneath an upper zone of exponential decline.