Technical progress of processing methods for magnetotelluric sounding data
ZHANG Kun1,2,3,4, LIU Lei5, MA Xingzhi1,2, YANG Yufan1,2
1. Chinese Academy of Geological Sciences,Beijing 100037,China; 2. Laboratory of Deep Earth Sciences and Technology of Ministry of Natural Resources, Beijing 100037, China; 3. East China Institute of Technology, Jiangxi Nanchang, 330013, China; 4. Key Laboratory of Geophysical Electromagnetic Probing Technologies of Ministry of Natural Resources, Hebei Langfang 065000, China; 5. Geophysical Exploration Brigade of Hubei Geological Bureau, Hubei Wuhan 430056, China
Abstract：The magnetotelluric sounding method is widely used in researches on geodynamics, metallogenic system, deep exploration of mineral resource and clean/oil energy and investigation of geological disaster, due to its advantages of large detection depth, penetrating high resistance layers, portable performance and low cost. However, the performance of this method is weak in natural electromagnetic field signals observation, which is easily interfered by noise. The effective electrical information is obtained by long-term observation and multiple superposition, and the related data processing and analysis methods were used to obtain reliable geo-electrical results. Data processing usually includes time-frequency conversion, denoising, estimation of impedance tensor and tipper vector, and data analysis includes electrical strike direction and medium dimension analysis. In this paper, the authors summarized the widely used processing methods for magnetotelluric sounding data, based on previous research and introduced the forefront research directions and achievements focusing on denoising in data processing and impedance and phase tensor in data analysis. The characteristics and advantages of the existing methods, and the applicability to geomagnetic field observation data under different environments and backgrounds were analyzed to provide theorical information and basic guarantee for effective and efficient application of magnetotelluric sounding.
[1] Tikhonov A.The determination of electrical properties of deep la-yer of the Earth's crust[J].Doklady Akademii Nauk Sssr,1950,73:295-297. [2] Cagniard L.Basic theory of the magneto-telluric method of geophysical prospecting[J].Geophysics,1953,18(3):605-635. [3] 吕庆田,吴明安,汤井田等.安徽庐枞矿集区三维探测与深部成矿预测[M].北京:科学出版社,2018. Lv Q T,Wu M G,Tang J T,et al.Three-dimensional Detection and Deep Mineralization Prediction of Lucong Ore Cluster in Anhui Province[M].Beijing:Science Press,2018. [4] Zhang K,Lv Q T,Zhao J H,et al.Magnetotelluric evidence for the multi-microcontinental composition of eastern South China and its tectonic evolution[J].Scientific Reports,2020,10(1):13105. [5] Zhang K,Lv Q T,Yan J Y,et al.The three-dimensional electrical structure and metallogenic prospect of the Ning (Nanjing)-Wu (Wuhu) basin and the southern adjacent area in eastern China[J].Journal of Asian Earth Sciences,2019,173:304-313. [6] Zhang K,Lv Q,Zhao J,et al.Intra-continental Orogeny:Insights from Magnetotelluric Data into the Mesozoic Uplift History of the Eastern Jiangnan Orogen in South China[J].Acta Geologica Sinica-English Edition,2023,97(1):55-67. [7] Zhang Kun,Lv Q T,Yan J Y,et al.The electrical resistivity signature of a fault controlling gold mineralization and the implications for Mesozoic mineralization:A case study from the Jiaojia Fault,eastern China[J].Acta Geophysica; 2017a,65(2):1-15. [8] Zhang Kun,Lv Q T,Yan J Y,et al.Crustal structure beneath the Jiaodong Peninsula,North China,revealed with a 3D inversion model of magnetotelluric data[J].Journal of Geophysics & Engineering; 2018,15 2442-245. [9] 赵凌强,孙翔宇,詹艳,等.银川盆地三维深部电性结构特征及其地球动力学意义[J].中国科学:地球科学,2023,53(3):481-496. Zhao L Q,Sun X Y,Zhan Y,et al.Three-dimensional deep electrical structure characteristics of Yinchuan Basin and its geodynamic significance[J].Science China:Earth Sciences,2023,53(3):481-496. [10] 薛国强,陈卫营,赵平,等.西藏羊八井地热田三维电性结构模型——来自大地电磁的证据[J].中国科学:地球科学,2023,53(08):1859-1871. Xue G Q,Chen W Y,Zhao P,et al.Three-dimensional electrical structure model of Yangbajing geothermal field in Tibet:Evidence from magnetotellurics[J].Science China:Earth Sciences,2023,53(08):1859-1871 [11] 张昆. 华南地区大地电磁应用示范[Z].北京:地质调查项目进展报告,2023. Zhang K.Demonstration of magnetotelluric applications in South China[Z].Beijing:Geological Survey Project Progress Report,2023. [12] 张昆. 改进的大地电磁场非线性共轭梯度三维反演及其并行计算研究[D].北京:中国地质大学(北京),2013. Zhang K.Research on Improved Three-dimensional Inversion of Nonlinear Conjugate Gradient of Magnetotelluric Field and Its Parallel Computing[D].Beijing:China University of Geosciences (Beijing),2013. [13] 陈乐寿,王光锷.大地电磁测深法[M].北京:地质出版社,1990. Chen L S,Wang G E.Magnetotelluric Sounding Method[M].Beijing:Geological Publishing House,1990. [14] Zhang K,Wei W B,Lv Q T.Four changes for efficiency and practicality on previous 3D MT NLCG inversion algorithm[J] Acta Geod Geophys,2014,49:551-563. [15] Zhang K,Yan J Y,Lv Q T,et al.Three-dimensional nonlinear conjugate gradient parallel inversion with full information of marine magnetotellurics[J].Journal of Applied Geophysics,2017b,139:144-157. [16] 崔金岭. 强干扰地区电磁噪声与大地电磁测深数据处理新方法研究[D].北京:中国地质大学(北京),2014. Cui J L.Research on New Methods of Electromagnetic Noise and Magnetotelluric Sounding Data Processing in Strong Interference Areas[D].Beijing:China University of Geosciences (Beijing),2014. [17] 林昌洪,谭捍东,佟拓.倾子资料三维共轭梯度反演研究[J].地球物理学报,2011.,54(4):1106-1113. Lin C H,Tan H D,Tong T.Study on three-dimensional conjugate gradient inversion of dipole data[J].Chinese Journal of Geophysics,2011.,54(4):1106-1113. [18] 自然资源部.DZ/T 0173—2022大地电磁测深法技术规程大地电磁测深法技术规程[S].北京:地质出版社,2022. Ministry of Natural Resources.DZ/T 0173—2022 Technical Specifications for Magnetotelluric Sounding Technical Specifications for Magnetotelluric Sounding[S].Beijing:Geological Publishing House,2022. [19] 石应骏,刘国栋,吴广耀,等.大地电磁测深法教程[M].北京:地质出版社,1985. Shi Y J,Liu G D,Wu G Y,et al.Tutorial on Magnetotelluric Sounding[M].Beijing:Geological Publishing House,1985. [20] Fiona S,Karsten B.Practical magnetotellurics[M].Cambridge University Press,2005. [21] Parzen E.Mathematical Considerations in the Estimation of Spectra[J].Technometrics,1961,3(2):167-190. [22] Parzen E.Modern Probability Theory and Its Applications[M].online:John Wiley & Sons,1992. [23] Jenkins G W,Watts DG.Spectral Analysis and its Applications[J].San Francisco:Holden-Day,1968. [24] Egbert G D,Booker JR.Robust estimation of geomagnetic transfer functions[J].Geophysical Journal International,1986,87(1):173-194. [25] Mebane W,Sekhon J.Robust estimation and outlier detection for overdispersed multinomial models of count data[J].American Journal of Political Science,2004,48(2):392-411. [26] Jones A G,Chave AD,Egbert G,et al.A comparison of techniques for magnetotelluric response function estimation[J].Journal of Geophysical Research:Solid Earth,1989,94(B10):14201-14213. [27] Gamble T D,Goubau WM,Clarke J.Magnetotellurics with a remote magnetic reference[J].Geophysics,1979,44(1):53-68. [28] 徐义贤,王家映.基于连续小波变换的大地电磁信号谱估计方法[J].地球物理学报,2000,43(5):677-683. Xu Y X,Wang J Y.Spectrum estimation method of magnetotelluric signals based on continuous wavelet transform[J].Chinese Journal of Geophysics,2000,43(5):677-683. [29] Garcia X,Jones A G.Robust processing of magnetotelluric data in the AMT dead band using the continuous wavelet transform[J].Geophysics,2008,73(6):F223-F234. [30] 汤井田,李晋,肖晓,等.数学形态滤波与大地电磁噪声压制[J].地球物理学报,2012,55(5):1784-1793. Tang J T,Li J,Xiao X,et al.Mathematical morphology filtering and magnetotelluric noise suppression[J].Chinese Journal of Geophysics,2012,55(5):1784-1793. [31] Egbert G D.Robust multiple-station magnetotelluric data processing[J].Geophysical Journal International,1997,130(2):475-496. [32] Larsen J C,Mackie R L,Manzella A,et al.Robust smooth magnetotelluric transfer functions[J].Geophysical Journal International,1996,124(3):801-819. [33] Wang L,Meng X F.An adaptive Generalized S-transform for instantaneous frequency estimation[J].Signal Processing,2011,91(8):1876-1886. [34] 周竹生,陈友良.含可变因子的广义S变换及其时频滤波[J].煤田地质与勘探,2011,39(6):63-66. Zhou Z S,Chen Y L.Generalized S transform with variable factors and its time-frequency filtering[J].Coal Geology and Exploration,2011,39(6):63-66. [35] Liu J,Yao J,Liu X.Generalized S transform with adaptive optimized window and its application in seismic signal analysis[J].Information Technology Journal,2013,12(2):276. [36] Back A D,Weigend A S.A first application of independent component analysis to extracting structure from stock returns[J].International journal of neural systems,1997,8(04):473-484. [37] Chave A D,Thomson D J.Bounded influence magnetotelluric response function estimation[J].Geophysical Journal International,2004,157(3):988-1006. [38] Egbert G D.Processing and interpretation of electromagnetic induction array data[J].Surveys in geophysics,2002,23(2/3):207-249. [39] 周聪,汤井田,原源,等.强干扰区含噪电磁场的时空分布特征[J].吉林大学学报:地球科学版,2020,50(6):17. Zhou C,Tang J T, Yuan Y,et al. Temporal and spatial distribution characteristics of noisy electromagnetic fields in strong interference areas[J].Journal of Jilin University:Earth Science Edition,2020,50(6):17. [40] Huber P J.Robust Statistics[M].New York:Wiley,1981. [41] Swift C M.A Magnetotelluric Investigation of An Electrical Conductivity Anomaly in the Southwestern United States[D].Massachusetts Institute of Technology,1967. [42] 谢成良. 大地电磁测深资料综合处理软件系统研究[D].北京:中国地质大学 (北京),2013 Xie C L.Research on Software System for Comprehensive Processing of Magnetotelluric Sounding Data[D].Beijing:China University of Geosciences (Beijing),2013. [43] Bahr K.Interpretation of the magnetotelluric impedance tensor:regional induction and local telluric distortion[J].Journal of geophysics,1988,62(1):119-127. [44] Groom R W,Bailey R C.Decomposition of magnetotelluric impedance tensors in the presence of local three-dimensional galvanic distortion[J].Journal of Geophysical Research:Solid Earth,1989,94(B2):1913-1925. [45] Zhang K,Wei W,Lu Q,et al.Correction of magnetotelluric static shift by analysis of 3D forward modelling and measured test data[J].Exploration Geophysics,2016,47. [46] Caldwell T G,Bibby H M,Brown C.The magnetotelluric phase tensor[J].Geophysical Journal International,2004,158(2):457-469. [47] Bibby H,Caldwell T,Brown C.Determinable and non-determinable parameters of galvanic distortion in magnetotellurics[J].Geophysical Journal International,2005,163(3):915-930. [48] Parkinson W D.The influence of continents and oceans on geomagnetic variations.Geophysical Journal International[J].Geophysical Journal International,1962,6(4):441-449.
2024, Vol. 11 
