Geothermal gradient and heat flow of the Erlian Basin and adjacent areas, Northern China: Geodynamic implication

Abstract

The Erlian Basin, located in the eastern Central Asian Orogenic Belt (CAOB) between North China and the Siberian cratons, is a Mesozoic basin developed on a fold basement. A good understanding of the thermal regime in this area allows for greater insight into the geodynamic processes of the CAOB. In this study, geothermal gradient and heat flow of the Erlian Basin were assessed using temperature logs from 14 boreholes and rock thermal conductivity data. The results show that the geothermal gradients of the Erlian Basin range from 29.6 ℃/km to 51.4 ℃/km with an average of 39.1 ± 5.4 ℃/km. The heat flow varies between 63 mW/m2 and 109.5 mW/m2 with a mean of 81.4 ± 12.0 mW/m2. High anomalous zones occur in the Manite, Uliastai and Chuanjing depressions, with geothermal gradient values of approximately 40–60 °C/km and heat flow of approximately 80–110 mW/m2. The heat flow anomalies are consistent with the distribution of Cenozoic volcanoes, which may provide hot material from the deep mantle. The contributions of the excessive heat from the intruded bodies to the present-day surface heat flow anomaly are estimated to be about 7–9 mW/m2 in the Uliastai Depression and 17–20 mW/m2 in the Manite Depression, respectively. The characteristics of the geothermal regime of the Erlian Basin is a consequence that the subduction and rollback of the Pacific Plate had triggered regional lithospheric extension and upwelling of deep mantle material, basaltic melts entered the lithosphere along the fragile zone resulted from the closure of the Paleo-Asian Ocean.