Heat flow, lithospheric thermal structure, and its tectonic implication of the Southern North China Basin, East-central China

Heat flow is a fundamental parameter in geothermal research. It not only complements seismic data by providing significant constraints on lithospheric thickness, geophysical properties, and tectonic evolution, but it is also vital for the evaluation and selection of geothermal resource sites. In this study, we conducted systematic measurements of steady-state temperature, thermal conductivity, and heat production from ten boreholes in the Southern North China Basin (SNCB), East-central China. These measurements yielded ten high-quality heat flow values. Combining these new data with previous research, we developed 2D temperature models and calculated lithospheric thickness. Our results reveal that heat flow in the SNCB follows a "lower in the north, higher in the south" pattern, with an average geothermal gradient of 25±5 °C/km and an average heat flow value of 57±12 mW/m². The lithospheric thickness varies significantly across the region, being approximately 105 km in the northwestern margin of the basin, increasing to 140–150 km in the eastern Huaibei Uplift, and decreasing to around 83 km in the neighboring Lower Yangtze Craton. This study not only provides geodynamic insights into variations in the thermal state of cratonic regions but also offers critical data to enhance our understanding of lithospheric structure, tectono-thermal evolution, and geothermal resource potential in the SNCB and adjacent areas.