| 基于重磁异常的北京副中心地质构造特征和地热控制作用研究 |
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| 关键词:gravity anomaly geothermal gravity and magnetic inversion Theta map Beijing sub-center |
| 基金项目:中国地质调查局地质调查项目(编号: 12120114033901; DD20160229);北京市地质矿产勘查开发局市级财政项目(编号: PXM2016_158307_000013; PXM2017_158307_000008);国家自然科学基金项目(编号: 41877197) |
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| 摘要: |
| Gravity and Magnetic Study of Structure and Associated Geothermal System in Beijing Sub-center |
| Gravity and magnetic exploration is very important for analyzing the characteristics and genesis of geothermal system. At present, the geothermal development of Beijing’s sub center is still not enough. In order to provide a geophysical basis for sustainable utilization of geothermal resources, the edge detecting of the potential fields, 2.5D profile inversion and 3D inversion calculation were carried out for the latest 1: 50 000 high-resolution regional gravity survey data. Using the normalized Theta diagram vertical derivative and the first order horizontal derivative, we obtained the fault location with higher accuracy and studied its intersection characteristics. Using Parker-Oldenburg method in frequency domain, the bedrock burial conditions of two profiles in different directions was obtained by 2.5D inversion. Using the trust region inversion algorithm, the apparent density anomaly characteristics of strata less than 5 km in depth was obtained by 3D inversion. On this basis, combined with 1:100 000 aeromagnetic and borehole data analysis, the geological structure characteristics and geothermal control of the sub-center were comprehensively studied. The conclusions are as follows: (1) the faults in the study area are mainly NE–trending and NW-trending. The NE–trending faults have strong continuity and wide gradient zone of gravity anomaly, but are reconstructed obviously by NW–trending faults. (2) The differential uplift of Archaean crystalline basement makes great changes in the thickness of geothermal reservoir and cap rock in the study area. The thickness of Jixian system reservoir in the southern uplift becomes thinner or missing. The thickness of Cenozoic cap rock is 200~800 m in uplift area and more than 2000 m in fault basin area. (3) Nanyuan–Tongxian fault and Xiadian fault are excellent heat control and water transfer channels in the study area. The NW-trending faults including Taihu fault, Zhangjiawan fault, and NE-trending faults including Yanjiao fault and Yaoxinzhuang fault are also the main water diversion channels in the study area. They intersect with Nanyuan–Tongxian fault and Xiadian fault to form three main runoff channels. There are great differences in oc-currence characteristics of geothermal anomalies controlled by different structures. |
| LEI Xiao-dong,ZHAO Yu,TANG Xian-chun,WANG Li-fa,HE Fu-bing,GUAN Wei,LI Juan.2023.Gravity and Magnetic Study of Structure and Associated Geothermal System in Beijing Sub-center[J].Acta Geoscientica Sinica,44(1):79-92. |
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