Surface Heat Flow, Deep Formation Temperature, and Lithospheric Thickness of the Different Tectonic Units in Tarim Basin, Western China

Abstract

Abstract Herein, the new collected well-testing temperature as well as continuous steady-state temperature logs were achieved for the analysis of deep thermal structural characteristics and current thermal states of various tectonic units in Tarim Basin. Generally, geothermal gradient fluctuates in 14.6-31.1°C/km, the heat flow ranges between 31.6 and 59.2 mW/m2 with the average heat flow of 43.2 mW/m2, and these values are typical of low heat flow background in Precambrian craton basins. Furthermore, estimated formation temperature spatial distributions at 6~8 km depth are the same and are mainly under the control of basement structural pattern. At 6000 m depth, temperature is 99-188°C, which become 126-242°C and 113-215°C at 7000 m and 8000 m depths, respectively. These findings confirmed that heat flow in Tarim Basin was relatively low with similar geothermal regimes to other Precambrian craton basins around the globe. In addition, 1D theoretical crustal thermal structures in Tarim Basin were established based on the solution of the equation of steady-state heat conduction. The findings revealed that “thermal” lithosphere maximum thickness in Tarim Basin is witnessed in Manjiaer sag. Tazhong uplift thermal state differs from those of Tabei uplift and Manjiaer sag. Tazhong mantle heat flow is 23.9 mW/m2, which accounts for 48.8% of surface heat flow. Hotter thermal states of Tazhong uplift generated temperatures as high as ∼690°C in Moho. Tarim Basin heat flow distribution reveals that crustal heat flow plays a more significant role in surface heat flow and possesses typical “hot crust and cold mantle” model thermal structure properties.