Terrestrial heat flow of Jizhong depression, China, Western Bohai Bay basin and its influencing factors

• Published in: Geothermics 2021-11, Vol.96, p.102210, Article 102210
• Main Authors: Wang, Zhuting, Rao, Song, Xiao, Hongping, Wang, Yibo, Jiang, Guangzheng, Hu, Shengbiao, Zhang, Chao
• Format: Article
• Language: English
• Subjects: Boreholes; Conduction heating; Conductive heat transfer; Dolomite; Geothermal power; Heat conductivity; Heat flow; Heat transfer; Heat transmission; Magma; Metamorphic rocks; Permeability; Radiogenic heat production; Sandstone; Temperature distribution; Temperature influence factors; Terrestrial environments; Thermal conductivity; Thickness; Uplift
• ISSN: 0375-6505; 1879-3576
• DOI: 10.1016/j.geothermics.2021.102210

•Continuous steady-state temperature logs were obtained from 14 deep boreholes. 135 core samples for thermal conductivity and radiogenic heat production were measured. Combined the continental china heat flow database with the newly measured heat flow values, heat flow distribution in Jizhong depression were analyzed. Finally, the factors influencing shallow temperature, such as the lateral sediment thickness variations and magma activity, were talked. The Jizhong depression in the western Bohai Bay Basin has a high thermal state. Heat flow is one of the most important parameters in geothermics, its measurement can help obtain a better understanding of the regional lithospheric thermal structure. In this study, continuous steady-state temperature logs were obtained from 14 deep boreholes. 136 core samples were measured for thermal conductivity and radiogenic heat production. The temperature data indicated that heat transfer within the sedimentary layer was dominated by heat conduction, with a geothermal gradient of approximately 31.5 ℃•km−1. The gradient value was almost 0 ℃•km−1 in the dolomite strata, due to their abnormally high thermal conductivity and permeability. Average thermal conductivity values was 2.46, 5.51 and 3.21 W•m−1•K−1, and the radiogenic heat production were 1.05, 0.26, and 0.74 μW•m−3 for the sandstone, dolomite and metamorphic rocks, respectively. Higher heat flow in the Jizhong depression is mainly distributed around the subsurface structure of sub-uplift region, which is near the fault between the sub-uplift region and the sub-depression region, and the value can reach 120.0 mW•m−2. With an increase in the dolomite buried depths or an increase in the overlying sandstone thickness, the surface heat flow value decreases. Finally, we discuss the factors influencing the shallow temperature: the lateral sediment thickness variations can markedly influence the temperature distribution. The influence of magma activity that happened long ago can be neglected.