Mantle heat flow in the territory of Ukraine

The article describes the second stage of studying the thermal field of Ukraine. We considered two options for calculating the mantle heat flow. The first variant (HFm1) was a calculation of the difference between the observed heat flow and the heat flow determined at the first study stage caused by radiogenic heat generation in the crustal rocks. In the second variant, we calculated the mantle heat flow (HFm2) as the sum of several effects. We considered the general cooling of the Earth, heat generation in immobile rocks of the upper mantle, and the reflection of heat and mass transfer processes in the tectonosphere (practically — only in the Phanerozoic). The latter also includes recent activation. Calculations have shown that a significant difference between the platform and geosyncline existed in the last approximately 2.5 billion years, and the contribution to the present-day conductive heat flow from the mantle in these regions does not differ significantly. The difference in the released energy is compensated by a different number of convective heat and mass transfer events. The effects of recent events are considered for cases when they are still noticeable in the modern mantle heat flow. In practice, this applies to the Hercynian and younger geosynclines. These effects were calculated for the Donbas, the Lublin-Lviv Trough, the Scythian Plate, and the Carpathians. Particular attention is paid to recent activation, the deep process of which is not fully understood. The calculations of both variants coincide on the territory of Ukraine with acceptable accuracy. Thus, the heat and mass transfer schemes adopted by the authors have been controlled by independent data. The results allow us to proceed to the third stage of the study — the construction of a complete thermal model of the tectonosphere of Ukraine.