Potential effects of upward throughflow on thermal structure models within the continental lithospheric mantle-crust

Heat transfer problems between the lithospheric mantle and crust are similar to large-scale heat transfer problems in porous media. The main purpose of this paper is to investigate the potential effect of upward throughflow on the thermal structure model within the continental lithospheric mantle-crust. Based on the preliminary theoretical results from the porosity-wave induced heat-transfer and mass-transport model, it is indicated that it is important to use a combination of theoretical and numerical approaches for solving lithospheric mantle-crust heat transfer problems. The theoretical approach is used to determine the thickness and the related boundary conditions of the continental crust at the lithospheric scale, so that some important information can be provided accurately for establishing a numerical model of the crustal scale. On the other hand, the numerical approach can be used to simulate the detailed structures and complicated geometries of the continental crust at the crustal scale. If the thermal distribution in the crust is of the primary interest, the use of a reasonable numerical model at the crustal scale results in a significant reduction in computer efforts. Not only can the analytical solutions for the relationship between the continental lithosphere thickness and the mantle conductive heat flux at the lithospheric scale be useful for validating numerical methods in dealing with lithosphere-scale heat transfer problems, but also they can be used to investigate the fundamental issues related to thermal distributions within the continental lithosphere. Thus, these analytical solutions can provide correct thermal boundary conditions for numerically solving lithosphere thermal-thinning problems associated with mantle thermal events. Good agreement between the thermal structure types obtained from the present analytical solutions and those obtained from the geophysical and geological observations indicates that the generation and propagation of porosity waves are one of the potential mechanisms for material and energy exchange between the continental lithospheric mantle and the crust, which may affect the lithospheric thermal structures significantly.