Quantitative Expression of Heat Flow versus Tectonic Deformation in the China Continent: The Effects of Plastic-Flow Network and Stable Block

Abstract

Based on the heat flow data published in 1990 and 2001, a study of the factors influencing the terrestrial heat flow distribution in the China continent and its quantitative expression is carried out using the “Netlike Plastic‐Flow” continental dynamics model and the methods of statistic analysis and optimum fitting. The result indicates that the factors influencing the heat flow distribution is classified into two groups, i.e. background and tectonic ones, in which the former mainly involves the nonuniform distribution of mantle heat flow, heat production of radioactive elements in the crust, heat‐transfer media and hydrothermal circulation, while the latter mainly involves plastic‐flow networks and relatively‐stable blocks. The plastic‐flow network is a manifestation of shear localization in the netlike plastic‐flow process in the lower lithosphere, which is composed of two sets of plastic‐flow belts (PFBs) intersecting each other and, as one of the basic action regimes, controls the intraplate tectonic deformation. Relatively stable blocks (RSBs), which are the tectonic units with relatively‐high viscosities existing in the netlike plastic‐flow field, as one of the principal origins, result in the development of large‐scale compressional basins. PFB and RSB, as the active and quiet states of tectonic deformation, give rise to the higher and lower heat flow values, respectively. The provincial average heat flow in continent can be estimated using the expression qav= q0 + a Pbt–c Pbk, where the three terms of the right side are background heat flow, PFB‐positive contribution and RSB‐negative contribution, Pbt and Pbk are the PFB‐ and RSB‐coverage ratios, respectively, a is the coefficient of PFB‐positive contribution depending mainly on the strain in the lower lithosphere, and c is the coefficient of RSB‐negative contribution related mainly to the thickness of the lithosphere, the aseismic‐area ratio and the tectonic age. For the major portion of the China continent excluding some of the southeastern region of China, the confidence interval of the provincial average background heat flow is q0=57.2±24.8 mW/m2 and the PFB‐positive‐ and RSB‐negative‐contribution coefficients are α=14.8–71.9 mW/m2 and c=0–25.6 mW/m2, respectively. The concepts of PFB and RSB effects and the heat flow expression suggested provide a new choice of the approach to the quantitative description of the characteristics of heat flow distribution in continent and their physical mechanisms.