松辽盆地北部地热场深部控制因素研究:基于大地电磁探测的结果  

Deep controlling factors of the geothermal field in the northern Songliao basin derived from magnetotelluric survey

作　　者：牛璞 韩江涛[1,2] 曾昭发 侯贺晟[3] 刘立家 马国庆[1,2] 管彦武[1,2] NIU Pu;HAN JiangTao;ZENG ZhaoFa;HOU HeSheng;LIU LiJia;MA GuoQing;GUAN YanWu(College of Geo-exploration Science and Technology,Jilin University,Changchun 130026,China;Key Laboratory of Applied Geophysics,Ministry of Natural Resources,Changchun 130026,China;SinoProbe Center,Chinese Academy of Geological Sciences and China Geological Survey,Beijing 100037,China)

机构地区：[1]吉林大学地球探测科学与技术学院,长春130026 [2]自然资源部应用地球物理重点实验室,长春130026 [3]中国地质调查局中国地质科学院地球深部探测中心,北京100037

出　　处：《地球物理学报》2021年第11期4060-4074,共15页Chinese Journal of Geophysics

基　　金：国家重点研发专项(2017YFC0601305);国家自然科学基金项目(41504076);中国地质调查项目(DD20160207,DD20190010);吉林省科技发展计划项目(20180101093JC);中央高校基本科研业务费专项资金联合资助.

摘　　要：松辽盆地北部存在中低温地热场,地热场呈现中间高、四周环状降低的特征.松辽盆地内部形成高地热场的主要因素,一是深部热源供给;二是浅部热能储集.通过深部结构特征研究可揭示热源及热储的分布及相互联系,对松辽盆地北部地热场成因研究具有重要意义.为了揭示松辽盆地北部地热场的深部控制因素,本文基于古龙镇至依安县的246 km长大地电磁剖面,对71个宽频测点数据通过傅里叶变换、Robust估计以及相位张量分解等处理手段,在精细分析维性特征及电性主轴的基础上,利用非线性共轭梯度反演获得了剖面40 km深二维电性结构模型.研究发现:电阻率模型具有“纵向分层,横向分块”的特征,以水热性温泉富集的林甸地区为界,剖面南北两侧电性结构存在明显的差异,南侧呈现“低阻-高阻-低阻”的三元电性结构,北侧呈现“低阻”的一元电性结构,这两种结构与地温场分布具有良好的对应关系,林甸以南的三元电性结构区对应高地热异常,以北的一元电性结构区热异常下降明显;林甸地区位于这两种端元的分界区,地表温泉丰富,且发育有基底断裂,为水热型地热发育的“热点”地区;林甸南北两侧深部存在两个高导体C1、C2,这与普遍认识的松辽盆地存在软流圈隆起有关,说明盆地下方具有统一的热源,部分熔融热物质作为深部热源向上传递热量,不同之处在于林甸以南地区,中地壳存在巨厚高阻特征的前寒武纪结晶基底R1,为地热的保存提供了有利条件,而林甸以北地区深部缺少聚集热量的结晶基底,导致地热异常迅速降低.There is a mid-low temperature geothermal field in the northern Songliao basin,which is characterized by a height in the center and a ring-shaped decline in the periphery.The main factor for the formation of the high geothermal field in this basin is the supply of deep heat sources;the second is the shallow thermal energy storage.The study of deep structural characteristics can reveal the distribution and interrelationship of heat sources and heat reservoirs,which is of great significance for the study of the genesis of the geothermal field in this area.This work attempts to reveal the deep control factors of the geothermal field in the northern Songliao basin based on a 246 km-long magnetotelluric(profile from Gulong Town to Yi′an County.The data of 71 broadband sites are processed by Fourier transform,Robust estimation and phase tensor decomposition.On the basis of fine analysis of dimensional characteristics and electrical main axis,the non-linear conjugate gradient method was used to perform two-dimensional inversion to construct a 40 km-depth electrical structure model.The study shows that the resistivity model has the characteristics of“vertical stratification and horizontal zoning”.Taking the hydrothermal hot springs enriched Lindian area as the boundary,there are obvious differences in the electrical structure between the north and south sides of the profile.The south side presents a“low resistance-high resistance-low resistance”ternary electrical structure,while the north side presents a“low resistance”unitary electrical structure.The two structures have a good corresponding relationship with the distribution of the ground temperature field.The three-element electrical structure to the south of Lindian corresponds to high geothermal anomalies,and the one-element electrical structure to the north has a significant decrease in thermal anomalies,while the Lindian area is located at the boundary of the two end members.This area has many hot springs and developed basement faults,which is a“hot

关 键 词：大地电磁测深 电性结构 地热场 松辽盆地北部 

分 类 号：P315[天文地球—地震学] P631[天文地球—固体地球物理学]