Heat flow from the earth's mantle toward the crust (Moho heat flow) is the main energy source of tectogenesis. During the active stage of tectogenesis, it should be several times greater than the normal value during the calm stage. A thermal coupling between the crust and upper mantle is studied.
Secular variations of temperature distribution and of surface heat flow of the crust are numerically calculated for various models of the Moho heat flow and crustal structure.
It is concluded that: (1) The temperature distribution within the crust is varied not only by the maximum value of the Moho heat flow and the crustal structure, but is considerably affected by a pattern of the Moho heat flow: (2) The maximum temperature attained within the crust is nearly proportional to the total heat given from the mantle: (3) To melt the crustal materials, superposition of effects of crustal thickening and of an increase of the Moho heat flow is preferable: (4) Judging from its thermal influence to the crust, the size of mantle convection, if it is existed, might be several hundred kilometers.