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  

Gravity and Magnetic Study of Structure and Associated Geothermal System in Beijing Sub-center

作　　者：雷晓东 赵玉 唐显春 王立发 何付兵 关伟 李娟 LEI Xiao-dong;ZHAO Yu;TANG Xian-chun;WANG Li-fa;HE Fu-bing;GUAN Wei;LI Juan(Beijing Institute of Ecological Geology,Beijing 100120;Chinese Academy of Geological Sciences,Beijing 100037;Beijing Institute of Geological Survey,Beijing 100195;Beijing Institute of Geothermal Research,Beijing 102218)

机构地区：[1]北京市生态地质研究所,北京100120 [2]中国地质科学院,北京100037 [3]北京市地质调查研究所,北京100195 [4]北京市地热调查研究所,北京102218

出　　处：《地球学报》2023年第1期79-92,共14页Acta Geoscientica Sinica

基　　金：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)联合资助。

摘　　要：重磁勘探对于分析地热系统特征和成因十分重要。北京城市副中心当前地热开发程度较低,为给地热资源可持续利用提供依据,对近期完成的1:50000高精度区域重力测量资料,开展了场源边缘检测、2.5D剖面反演和三维反演计算。利用归一化Theta图垂向导数和一阶水平方向导数获得了精度更高的断裂位置,研究了断裂汇交特征;使用频率域Parker-Oldenburg方法反演获得了两条不同方向剖面的基岩起伏形态;使用信赖域反演算法获得了5 km以浅地层三维视密度异常特征。在此基础上结合1:100000航磁和钻孔资料分析,综合研究了副中心地质构造特征及其地热控制作用,得到结论如下:(1)研究区断裂构造以近NE向和NW向为主。NE向断裂延伸较远、梯度带宽,但被NW向断裂切割改造迹象明显。(2)太古界结晶基底差异性隆升使区内储层和盖层厚度变化大。研究区南部隆起区蓟县系储层厚度变薄或缺失。新生界盖层在隆起区厚度为200~800 m,在断陷盆地区达2000 m以上。(3)南苑—通县断裂和夏垫断裂是区内良好导热构造;NW向台湖断裂、张家湾断裂与NE向燕郊断裂、姚辛庄断裂是主要导水通道,与南苑—通县断裂和夏垫断裂交汇形成区内地热资源的主要补给径流通道。区内地热异常受不同级次构造控制在赋存特征上呈现较大差异。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 1:50000 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 1:100000 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

关 键 词：重力异常 地热 重磁反演 Theta图 北京副中心 

分 类 号：P631[天文地球—地质矿产勘探] P314[天文地球—地质学]