| 滇西三江构造带电性结构特征——以福贡—巧家剖面为例 |
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| 引用本文： | 罗愫,于常青,张刚,李德伟,瞿辰,张慧民,田镇瑜,皇健.滇西三江构造带电性结构特征——以福贡—巧家剖面为例[J].地球物理学报,2020,63(3):1026-1042. |
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| 作者姓名： | 罗愫 于常青 张刚 李德伟 瞿辰 张慧民 田镇瑜 皇健 |
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| 作者单位： | 1. 中国地质大学(武汉)地球物理与空间信息学院, 武汉 430074;2. 中国地质科学院地质研究所, 北京 100037;3. 西南科技大学环境资源学院, 四川绵阳 621010;4. 成都理工大学, 成都 610059;5. 中国地质大学(北京)地球物理与信息技术学院, 北京 100083 |
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| 基金项目： | 国家重点研发计划专题"深层地球物理信息与识别技术（2016YFC060110602）"和中国地质调查局项目（1212011121273，DD2016002）联合资助. |
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| 摘 要： | 为查明滇西三江构造带及邻区复杂的构造特征,并揭示该区深部电性结构,沿福贡—巧家布设了一条长约410 km的大地电磁剖面.共观测到61个物理点,其中宽频大地电磁测点41个,长周期大地电磁测点20个.通过对采集到的数据进行一系列的处理、反演,得到了沿剖面的壳幔电性结构模型.并结合研究区内区域地质资料及其他地球物理资料,对剖面所经过的各个主要地质构造单元及主要断裂带进行了综合解释.电性结构模型揭示沿剖面地壳电性层次复杂,深部电性结构由西往东呈分块展布,横向变化大,壳内广泛发育低阻异常.在中甸构造带(香格里拉地块)和盐源—永胜构造带深部壳幔存在大规模低阻异常,这可能与地下局部熔融体和地热流有关;康滇构造带壳幔存在大规模高阻异常,表明地壳中曾经有地幔物质侵入;在大凉山构造带地下10~50 km深处存在一呈横向“半月形”展布的低阻体,电阻率值不满10Ωm,结合地质资料与前人的研究成果,推测该低阻体成因应与青藏高原东南缘“地壳管道流”有一定关联.
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| 关 键 词： | 滇西三江地区 中上地壳 大地电磁 电阻率 电性结构特征 |
| 收稿时间： | 2019-05-15 |
Deep electrical resistivity structure of the Sanjiang Area,western Yunnan: An example of the Fugong-Qiaojia profile |
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| LUO Su,YU ChangQing,ZHANG Gang,LI DeWei,QU Chen,ZHANG HuiMin,TIAN ZhenYu,HUANG Jian.Deep electrical resistivity structure of the Sanjiang Area,western Yunnan: An example of the Fugong-Qiaojia profile[J].Chinese Journal of Geophysics,2020,63(3):1026-1042. |
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| Authors: | LUO Su YU ChangQing ZHANG Gang LI DeWei QU Chen ZHANG HuiMin TIAN ZhenYu HUANG Jian |
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| Institution: | 1. School of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China;2. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;3. School of Environment and Resource, Southwest University of Science and Technology, Sichuan Mianyang 621020, China;4. Chengdu University of Technology, Chengdu 610059, China;5. School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China |
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| Abstract: | In order to explore the complicated structural features of the Sanjiang tectonic belt and its adjacent areas and reveal the deep electrical resistivity structure, we deployed a 410 km-long Magnetotelluric (MT) profile along the Fugong-Qiaojia area. A total of 61 physical points were observed, including 41 broadband MT sounding stations and 20 long-period magnetotelluric sounding stations. After processing, two-dimensional inversion of the observed field data yielded a crust and mantle electrical resistivity structure model along the profile. Combined with regional geological data and other geophysical data in the study area, the main tectonic units and fault zones passing through the profile are comprehensively interpreted. The resistivity model reveals that the crust and mantle electrical resistivity structure in the study area is transversely partitioned in the east-west direction. From east to west, the electrical anomaly thickness and burial depth are different. In the Zhongdian tectonic belt, there are large-scale low-resistivity zones in the middle and upper crust, which may be related to partial melting and heat flow. High-resistivity bodies exist in the middle and upper crust of the Kangdian tectonic belt, indicating that there are mantle materials intruding into the crust. There is a low-resistance body at depths of 10~50 km in the Daliang Shan tectonic belt, which looks like half-lunar shaped, and the resistivity value is less than 10 Ωm. Based on the geological data and previous research results, it is speculated that the cause of the low-resistance body could be related to the "crustal channel flow" on the southeast margin of the Tibetan Plateau. |
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| Keywords: | Sanjiang area in western Yunnan Upper and middle crust Electrical resistivity Magnetotelluric sounding Electrical resistivity structure |
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