滇西三江构造带电性结构特征——以福贡-巧家剖面为例
中国地质大学(武汉)地球物理与空间信息学院, 武汉 430074
中国地质科学院地质研究所, 北京 100037
西南科技大学环境资源学院, 四川绵阳 621010
成都理工大学, 成都 610059
中国地质大学(北京)地球物理与信息技术学院, 北京 100083
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
中图分类号:P541;P631
School of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China
Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
School of Environment and Resource, Southwest University of Science and Technology, Sichuan Mianyang 621020, China
Chengdu University of Technology, Chengdu 610059, China
School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China
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10 Ωm，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.
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.
图 1研究区构造简图
研究区构造简图
图 2大地电磁测线测线位置
大地电磁测线测线位置
Figure 2.Map showing location of the magnetotelluric sounding line and tectonic setting in the study area
Map showing location of the magnetotelluric sounding line and tectonic setting in the study area
图 3相位张量分解得到的沿测线椭圆分布特征及二维偏离度(100 Hz、10 Hz、100 s、10000 s)
相位张量分解得到的沿测线椭圆分布特征及二维偏离度(100 Hz、10 Hz、100 s、10000 s)
Figure 3.Elliptic characteristics and skewness along the profile calculated by phase tensor decomposition
Elliptic characteristics and skewness along the profile calculated by phase tensor decomposition
图 4沿剖面经拼接后宽频+长周期大地电磁典型测点测深曲线
沿剖面经拼接后宽频+长周期大地电磁典型测点测深曲线
Figure 4.Scatter diagrams of MT+LMT sounding curves of typical stations along the profile
Scatter diagrams of MT+LMT sounding curves of typical stations along the profile
图 6不同模式反演模型
不同模式反演模型
Figure 6.Inversion models of different manners
Inversion models of different manners
图 5不同反演参数下的正则化因子曲线
不同反演参数下的正则化因子曲线
Figure 5.L-curve for regularization factor analysis with different inversion factors
L-curve for regularization factor analysis with different inversion factors
图 7实测的测深曲线与相应曲线的对比
实测的测深曲线与相应曲线的对比
Figure 7.Comparison of 2D calculated and measured responses
Comparison of 2D calculated and measured responses
图 8地质剖面与MT+LMT联合反演电性结构模型
地质剖面与MT+LMT联合反演电性结构模型
Figure 8.Geological section, 2-D crust and upper mantle resistivity electrical structure model from MT+LMT joint inversion
Geological section, 2-D crust and upper mantle resistivity electrical structure model from MT+LMT joint inversion
Cheng J, Liu J, Xu X W, et al. 2014. Tectonic characteristics of strong earthquakes in Daliangshan sub-block and impact of the MS6.5 Ludian earthquake in 2014 on the surrounding faults. Seismology and Geology (in Chinese), 36(4):1228-1243.
Cong B L. 1988. The Formation and Evolution of the Panxi Paleorift (in Chinese). Beijing:Science Press.
Dong M L. 2016. Study of magmatism in Tengchong-Baoshan block, western Yunnan and its tectonic implications[Ph. D. thesis] (in Chinese). Beijing: China University of Geosciences.
Hu G Y, Li Y H, Zeng P S. 2013. The role of halosalt in mineralization of the Jinding Pb-Zn deposit:Evidence from sulfur and strontium isotopic compositions. Acta Geologica Sinica (in Chinese), 87(11):1694-1702.
Huang J L, Wang S Y, Song X D. 2001. The Pn velocity structure and anisotropy at the top of upper mantle in Sichuan-Yunnan region and its adjacent area.//Proceedings of the 17th annual meeting of the Chinese Geophysical Society (in Chinese). Kunming: Yunnan Science Technology Press.
Huang J Q. 1994. On Major Tectonic Forms of China (in Chinese). 2nd ed. Beijing:Geological Publishing House.
Huang J Q, Chen B W. 1987. The Evolution of Tethys in China and Adjacent Regions. Beijing:Geological Publishing House.
Kong X R, Liu S J, Dou Q C, et al. 1987. Electrical conductivity structure in the crust and upper mantle in the region of Pan-Xi rift. Acta Geophysica Sinica (in Chinese), 30(6):136-143.
Metcalfe I. 2013. Gondwana dispersion and Asian accretion:Tectonic and palaeogeographic evolution of eastern Tethys. Journal of Asian Earth Sciences, 66:1-33.
Song F M, Wang Y P, Yu W X, et al. 1998. Xiaojiang Active Fault Zone (in Chinese). Beijing:Seismological Press.
Sun J, Jin G W, Bai D H, et al. 2003. Sounding of electrical structure of the crust and upper mantle along the eastern border of Qinghai-Tibet Plateau and its tectonic significance. Science in China Series D:Earth Sciences, 46(S2):242-253.
Ueno K. 2000. Permian fusulinacean faunas of the Sibumasu and Baoshan blocks, implications for the paleogeographic reconstruction of the Cimmerian continent. Geoscience Journal, 4:160-163.
Vozoff K. 1991. The magnetotelluric method.//Nabighian M N ed. Electromagnetic Methods in Applied Geophysics. Tulsa, OK, USA: Society of Exploration Geophysicists.
Wei W B, Jin S, Ye G F, et al. 2010. On the conductive structure of Chinese continental lithosphere——experiment on "standard monitoring network" of continental EM parameters (SinoProbe-01). Acta Geologica Sinica (in Chinese), 84(6):788-800.
Xia J W, Wu S Z, Zhu M. 2015. The feature, activity and seismic risk evaluation of Deccan faults. Journal of Geodesy and Geodynamics (in Chinese), 35(4):561-566.
Ye T. 2013. Deep electric structure beneath the Yingjiang-Longling area in southwestern Yunnan and its implications for kinetics[Master's Thesis] (in Chinese). Beijing: Institute of Geology, China Earthquake Administration.
Yunnan Bureau of Geology and Mineral Resources. 1990. Yunnan Regional Geology (in Chinese). Beijing:Geological Publishing House.
Zhang G. 2015. Research on long-period magnetotelluric data processing[Ph. D. thesis] (in Chinese). Chengdu: Chengdu University of Technology.
Zhang Z J, Bai Z M, Wang C Y, et al. 2005. The crustal structure under Sanjiang and its dynamic implications:Revealed by seismic reflection/refraction profile between Zhefang and Binchuan, Yunnan. Science in China Series D:Earth Sciences, 48(9):1329-1336.
Zhao G Z, Unsworth M J, Zhan Y, et al. 2012. Crustal structure and rheology of the Longmenshan and Wenchuan MW7.9 earthquake epicentral area from magnetotelluric data. Geology, 40(12):1139-1142.
程佳, 刘杰, 徐锡伟等. 2014.大凉山次级块体内强震发生的构造特征与2014年鲁甸6.5级地震对周边断层的影响.地震地质, 36(4):1228-1243.
从柏林. 1988.攀西古裂谷的形成与演化.北京:科学出版社.
董美玲. 2016.滇西腾冲-保山地块岩浆作用研究及其构造意义[博士论文].北京: 中国地质大学.
黄金莉, 汪素云, 宋晓东. 2001.川滇及邻区上地幔顶部Pn波速度结构及各向异性.//2001年中国地球物理学会年刊——中国地球物理学会第十七届年会论文集.昆明: 云南科技出版社.
黄汲清. 1994.中国主要地质构造单位. 2版.北京:地质出版社.
黄汲清, 陈炳蔚. 1987.中国及邻区特提斯海的演化.北京:地质出版社.
宋方敏, 汪一鹏, 俞维贤等. 1998.小江活动断裂带.北京:地震出版社.
叶涛. 2013.云南盈江-龙陵地区的深部电性结构及其动力学意义研究[硕士论文].北京: 中国地震局地质研究所.
云南省地质矿产局. 1990.云南省区域地质志.北京:地质出版社.
张刚. 2015.长周期大地电磁数据处理方法研究[博士论文].成都: 成都理工大学.
图(8)
返回顶部
Map showing location of the magnetotelluric sounding line and tectonic setting in the study area
Elliptic characteristics and skewness along the profile calculated by phase tensor decomposition
Scatter diagrams of MT+LMT sounding curves of typical stations along the profile
Inversion models of different manners
L-curve for regularization factor analysis with different inversion factors
Comparison of 2D calculated and measured responses
Geological section, 2-D crust and upper mantle resistivity electrical structure model from MT+LMT joint inversion