GEODYNAMICS

Abstract

Purpose of this work is to refine and complete the energy balance of the Earth's tectonosphere by thermal modeling. The methodology includes a detailed comprehensive analysis of heat generation in the crust and upper mantle throughout the studied geological history of the Earth for 4.2 billion years. Results. Experimental data on radiogenic heat generation in the Earth's crust and upper mantle are summarized. The need for a separate consideration of the heat balance for regions with different endogenous regimes on platforms, in geosynclines and oceans has been established. The average values of heat generation in the crust are about 0.4–0.5 µW/m3. In the upper mantle they are 0.04, 0.06, and 0.08 µW/m3, respectively. When taking into account the thicknesses of the solid crust (about 40 km under the platforms and geosynclines and about 6 km under the oceans) and the upper mantle (430-460 km), almost the same number of sources is found under all regions. They are distributed differently. This leads to different variants of geological history. It can be assumed that there are radiogenic heat sources with an intensity of about 0.02 μW/m3 in the transition zone to the lower mantle and in the lower mantle up to about 1100 km. At greater depths in the shell (the total mass of the Earth outside the core) and core, there are no sources. The energy balance of the tectonosphere is calculated for the platforms. Over 3.6 billion years (the period over which it is possible to describe the geological history quite accurately), about 73.5·1014 J/m2 has been carried out by the heat flow. The conductive heat flow during this time carried out 59.5·1014J/m2. The difference corresponds exactly to the needs of all active processes of this period. Originality. The experimental dates of the events also coincide with those calculated by the theory (some of which are for the first time). Practical significance. For the Phanerozoic geosynclines, such control has also been partially performed. The independently determined evolution of the mass flow (which is also of practical importance) in the geological history also agrees with the calculated values.