Estimation of heat flow in southeastern margin of Tibetan Plateau and its analysis of the correlation with earthquake activity

The southeastern margin of Tibetan Plateau is an area where geothermal resources are developed and earthquakes occur frequently due to the complete and intense geotectonic activities. Heat flow records the geothermic information about various tectonic movements that occur in the deep earth. It can be used as an effective constraint on geological tectonic activities and seismic activity studies. However, the heat flow data for large areas is difficult to achieve through logging technology. Hence, this paper estimates the surface heat flow and its value underground based on the Curie depth combing the radioactive elements distribution of the study area. Firstly, we calculate the surface heat production from the radioactive elements distribution. Secondly, we obtain the thermal conductivities of upper and lower layers of the crust by an iterative approach based on the relation between geothermal parameters. Finally, we obtain the surface heat flow and its value underground. The results show that: (1) The variation range of surface heat flow of southwestern margin of Tibetan Plateau is 44 similar to 108 mW . m(2) , and the mean is 75 mW . m(2) . It is in line with the background trend of high in southwest and low in northeast. The crustal heat flow value decreases as the depth increases. The majority of local high and low anomalies of surface heat flow are corresponding to the previous researches, such as west of Sichuan province, southeast of Tibet and west of Yunnan province are with high heat flow value; east of Sichuan province and Chuxiong are with low heat flow value. (2) Combined with other geophysical findings, the connection between the crustal heat flow at different depth and earthquake events is : earthquakes tend to occur in geothermal gradient zones where exist apparent differences of physical properties within a certain depth range on both sides of the gradient zone.