Heat flow, radiogenic heat and crustal thickness in southwest U.S.S.R.

Abstract

The heat flow distribution over the southwestern U.S.S.R. is dependent on two major factors: the thermal energy outflow from the deeper mantle during tectonic activation and the radiogenic heat generation in the upper lithospheric layers. The former is responsible for different levels of the thermal field in structures of a different age. The latter is manifest in the linear dependence of heat flow on radiogenic heat generation in subsurface layers of the earth's crust. The position of the M-discontinuity correlates weakly with heat flow and temperature distribution. The M-discontinuity is not an isothermal surface. However, within structures of the same age, heat flow values decrease with increasing crustal thickness. An analysis of the thermodynamic conditions on the continents shows that the crust-mantle interface cannot be explained by the gabbro to eclogite transition.