BEMD of Gravity and Magnetic Anomalies and Its Application in the Gangdise Belt's Crustal Structure
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摘要: 地壳结构是青藏高原深部地球物理探测的主要目标之一.研究了结合功率谱分析的二维经验模态分解（Bi-dimensional empirical mode decomposition，BEMD）位场分离方法，并将其应用于冈底斯带重磁异常分离中.模型试验结果表明该方法能够分离叠加异常，并可获得场源平均深度的可靠估计值；实际资料处理表明研究区布格重力异常和化磁极异常均可分为由浅到深的3个等效层场源产生的异常组合.其中深部重、磁场以南北分区、东西分块为特征.证明了青藏高原是南北地体的拼接，并且在形成之后持续受到印度板块不均匀地向北推进，使喜马拉雅地体、冈底斯地体的深部物质属性在东西方向上以约88°E和93°~95°E为界存在显著的差异；推断青藏高原南部区域中下地壳的低密度体东西向是不连续的，且在研究区中、东部，南北向低密度体被雅鲁藏布江缝合带切开.Abstract: Crustal structure is one of the main targets of deep geophysical exploration in the Qinghai-Tibet Plateau. In this paper, the bi-dimensional empirical mode decomposition (BEMD) separation method combined with power spectrum analysis is studied, and it is applied to the separation of gravity and magnetic anomalies in the Gangdise belt. The model test results show that the method can separate the superimposed anomalies and obtain a reliable estimation of the source depth. The decomposition results in the study area show that the bouguer and the RTP magnetic anomalies can be divided into three anomalies which are induced by three equivalent layer sources from shallow to deep. The deep gravity and magnetic fields are characterized by the north-south partition and the east-west block. It is proved that the Qinghai-Tibet Plateau is formed by splicing the terrains along the north-south direction and after its formation, it is continuously pushed northward by the Indian plate unevenly, which makes the material properties of the Himalayan terrain and the Gangdise terrain have significant differences in deep from east to west bounded by 88°E and 93°-95°E. It is inferred that the low density body is discontinuous in east-west direction and the low density body in the middle and east of the study area is cut by the Yarlung Zangbo suture zone.
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图 4 模型叠加异常及BEMD结果径向对数功率谱曲线
a.叠加异常功率谱；b.IMF1分量功率谱；c.RES分量功率谱
Fig. 4. The radial logarithmic power spectrum curves of superimposed anomaly and BEMD result
图 5 一阶趋势分析分离结果
a.一阶趋势分析局部异常；b.一阶趋势分析区域异常
Fig. 5. The result after analyzing first⁃order trend
图 6 二阶趋势分析分离结果
a.二阶趋势分析局部异常；b.二阶趋势分析区域异常
Fig. 6. The result after analyzing second⁃order trend
图 7 冈底斯带布格重力异常及BEMD结果
a.冈底斯带布格重力异常；b.冈底斯带重力异常IMF1分量；c.冈底斯带重力异常IMF2+IMF3分量；d.冈底斯带重力异常IMF4+RES分量；SMLMF.沙莫勒-麦拉-洛巴堆-米拉山断裂；GLZCF.噶尔-隆格尔-扎日南木错-措麦断裂带；SLYNJOMZ.狮泉河-拉果错-永珠-纳木错⁃嘉黎蛇绿混杂岩带；BNSZ.班公湖怒江缝合带；IYZSZ.印度河-雅鲁藏布江缝合带
Fig. 7. Bouguer gravity anomaly in the Gangdise belt and its result of BEMD
图 8 布格重力异常及BEMD结果功率谱曲线
a.重力异常垂向一阶导数功率谱曲线；b.IMF1分量垂向一阶导数功率谱曲；c.IMF2+IMF3垂向一阶导数功率谱曲线；d.IMF4+RES垂向一阶导数功率谱曲线
Fig. 8. The power spectrum curve of gravity anomaly and BEMD result
图 9 冈底斯带化极磁异常及BEMD结果
a.冈底斯带化极磁异常；b.冈底斯带化极磁异常IMF1分量；b.冈底斯带化极磁异常IMF2+IMF3分量；d.冈底斯带化极磁异常IMF4+RES分量
Fig. 9. The reduced to the pole aeromagnetic anomaly and its result of BEMD
图 10 化极磁异常及BEMD结果功率谱曲线
a.化极磁异常功率谱曲线；b.IMF1分量功率谱曲线；c.IMF2+IMF3分量功率谱曲线；d.IMF4+RES分量功率谱曲线
Fig. 10. The power spectrum curves of the reduced to the pole aeromagnetic anomaly and BEMD result
图 11 中下地壳重力异常与MT三维反演结果、接收函数结果对比
a.重力异常IMF2+IMF3分量；b.MT三维反演结果30 km深度水平切片图（Xie et al., 2016）；c.剖面接收函数结果（Xu et al., 2015）
Fig. 11. Comparison of gravity anomalies in middle⁃lower crust with 3D MT inversion results and receiver function imaging along profile
表 1 模型试验参数
Table 1. The parameters of model test
模型 x范围(m) y范围(m) z范围(m) 剩余密度(g/cm3) 正方体 -400~-800 -400~-800 100~500 0.5 正方体 -400~-800 400~800 100~500 0.5 正方体 400~800 -400~-800 100~500 0.5 正方体 400~800 400~800 100~500 0.5 长方体 -3 200~0 -3 200~3 200 600~1 000 0.5 长方体 0~3 200 -3 200~3 200 800~1 000 0.5 
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表 2 不同场分离方法均方差统计
Table 2. Statistic of mean variance for different separation methods
方法 BEMD 一阶趋势分析 二阶趋势分析 均方差(mGal) 0.185 0.232 0.25
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Al-Rahim, A.M., 2016.Separating the Gravity Field of Iraq by Using Bi-dimensional Empirical Mode Decomposition Technique.Arabian Journal of Geosciences, 9:43. https://doi.org/10.1007/s12517-015-2118-7 Alsdorf, D., Nelson, D., 1999.Tibetan Satellite Magnetic Low:Evidence for Widespread Melt in the Tibetan Crust? Geology, 27(10):943. doi: 10.1130/0091-7613(1999)027<0943:TSMLEF>2.3.CO;2 Blakely, R.J., Simpson, R.W., 1986.Approximating Edges of Source Bodies from Magnetic or Gravity Anomalies.Geophysics, 51(7):1494-1498. https://doi.org/10.1190/1.1442197 Chen, J. G., Xiao, F., Chang, T., 2011. Gravity and Magnetic Anomaly Separation Based on Bi-dimensional Empirical Mode Decomposition. Earth Science, 36(2):327-335(in Chinese with English abstract). https://doi.org/10.3799/dqkx.2011.034 Chen, J. L., Xu, J. F., Zhao, W. X., et al., 2011. Geochemical Variations in Miocene Adakitic Rocks from the Western and Eastern Lhasa Terrane:Implications for Lower Crustal Flow beneath the Southern Tibetan Plateau.Lithos, 125(3-4):928-939. https://doi.org/10.1016/j.lith-os.2011.05.006 Chen, T., Zhang, G. B., 2018. Forward Modeling of Gravity Anomalies Based on Cell Mergence and Parallel Computing. Computers & Geosciences, 120:1-9. https://doi.org/10.1016/j.cageo.2018.07.007 Clark, M.K., Royden, L.H., 2000.Topographic Ooze:Building the Eastern Margin of Tibet by Lower Crustal Flow.Geology, 28(8):703. doi:10.1130/0091-7613(2000)028<0703:tobtem>2.3.co;2 Duan, Y.H., Tian, X.B., Liang, X.F., et al., 2017.Subduction of the Indian Slab into the Mantle Transition Zone Revealed by Receiver Functions. Tectonophysics, 702:61-69. https://doi.org/10.1016/j.tecto.2017.02.025 Guo, Y. X., Wang, D. J., Zhou, Y. S., et al., 2017. Electrical Conductivities of Two Granite Samples in Southern Tibet and Their Geophysical Implications. Science China:Earth Sciences, 47(7):860-870(in Chinese). Guo, X. Y., Gao, R., Zhao, J. M., et al., 2018. Deep-Seated Lithospheric Geometry in Revealing Collapse of the Tibetan Plateau. Earth-Science Reviews, 185:751-762. https://doi.org/10.1016/j.earscirev.2018.07.013 Hetényi, G., Vergne, J., Bollinger, L., et al., 2011.Discontinuous Low-Velocity Zones in Southern Tibet Question the Viability of the Channel Flow Model.Geological Society, London, Special Publications, 353(1):99-108. https://doi.org/10.1144/sp353.6 He, R.Z., Gao, R., Zheng, H.W., et al., 2007.Matched-Filter Analysis of Aeromagnetic Anomaly in Mid-Western Tibetan Plateau and Its Tectonic Implications. Chinese Journal of Geophysics, 50(4):1131-1140(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqwlxb200704020 Hou, W. S., Yang, Z. J., Zhou, Y. Z., et al., 2012. Extracting Magnetic Anomalies Based on an Improved BEMD Method:A Case Study in the Pangxidong Area, South China. Computers & Geosciences, 48:1-8. https://doi.org/10.1016/j.cageo.2012.05.006 Huang, N.E., Shen, Z., Long, S.R., et al., 1998.The Empirical Mode Decomposition and the Hilbert Spectrum for Nonlinear and Non-Stationary Time Series Analysis. Proceedings of the Royal Society of London Series A:Mathematical, Physical and Engineering Sciences, 454(1971):903-995. https://doi.org/10.1098/rspa.1998.0193 Kong, X R, Wang, Q.S., 1996.Integrated Geophysics and Lithosphere in the Western Tibet Plateau Structural.Science in China (Series D), 26(4):308-315 (in Chinese). Nelson, K. D., Zhao, W., Brown, L. D., et al., 1996. Partially Molten Middle Crust beneath Southern Tibet:Synthesis of Project INDEPTH Results.Science, 274(5293):1684-1688. https://doi.org/10.1126/science.274.5293.1684 Shi, D. N., Wu, Z. H., Klemperer, S. L., et al., 2015. Receiver Function Imaging of Crustal Suture, Steep Subduction, and Mantle Wedge in the Eastern India-Tibet Continental Collision Zone.Earth and Planetary Science Letters, 414:6-15. https://doi.org/10.1016/j.epsl.2014.12.055 Teng, J.W., Zhang, H.S., Sun, R.M., et al., 2011.Geophysical Field Characteristics and Dynamic Response of Segmentations in East-West Direction and Their Boundary Zone in Central Tibetan Plateau. Chinese J. Geophys., 54(10):2510-2527(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqwlxb201110009 Wang, C.B., Chen, J.G., Xiao, F., et al., 2014.Application of Empirical Mode Decomposition and Independent Component Analysis in Aeromagnetic Data Processing.Journal of Geology, 38(4):623-629(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=jsdz201404015 Wei, W., 2001.Detection of Widespread Fluids in the Tibetan Crust by Magnetotelluric Studies. Science, 292(5517):716-719. https://doi.org/10.1126/science.1010580 Xie, C. L., Jin, S., Wei, W. B., et al., 2016. Crustal Electrical Structures and Deep Processes of the Eastern Lhasa Terrane in the South Tibetan Plateau as Revealed by Magnetotelluric Data.Tectonophysics, 675:168-180. https://doi.org/10.1016/j.tecto.2016.03.017 Xiong, S.Q., Zhou, F.H., Yao, Z.X., et al., 2007.Aero Magnetic Survey in Central and Westren Qinghai-Tibet Plateau.Geophysical and Geochemical Exploration, 31(5):404-407(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=wtyht200705005 Xu, Q., Zhao, J.M., Yuan, X.H., et al., 2015.Mapping Crustal Structure beneath Southern Tibet:Seismic Evidence for Continental Crustal Underthrusting. Gondwana Research, 27(4):1487-1493. https://doi.org/10.1016/j.gr.2014.01.006 Xue, D.J., Jiang, M., Wu, L.S., et al., 2006.East-West Division of Regional Gravity and Magnetic Anomalies on the Qinghai-Tibet Plateau and Its Tectonic Features.Geology in China, 33(4):912-919(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=zgdizhi200604021 Yang, W. C., Hou, Z. Z., Yu, C. Q., 2015. Three-Dimensional Density Structure of the Tibetan Plateau Mass Movement.Chinese J.Geophys., 58(11):4223-4234(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqwlxb201511029 Yuan, X.H., Ni, J., Kind, R., et al., 1997.Lithospheric and Upper Mantle Structure of Southern Tibet from a Seismological Passive Source Experiment.Journal of Geophysical Research:Solid Earth, 102(B12):27491-27500. doi: 10.1029/97JB02379 Zeng, Q. Q., Liu, T. Y., 2011. EMD of Gravity and Magnetic Iron Deposit Exploration in Anomalies and Its Application for Zhangfushan, Eastern Hubei. Progress in Geophysics, 26(4):1409-1414(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqwlxjz201104036 Zhang, S.X., Chen, C., Wang, L.S., et al., 2015.The Bi-dimensional Empirical Mode Decomposition and Its Applications to Denoising and Separation of Potential Field.Progress in Geophysics, 30(6):2855-2862(in Chinese with English abstract). Zhang, S. X., Chen, Z. H., Wang, T. Q., et al., 2018. The Extraction of Abnormal Feature of Mobile Gravity in the Sichuan-Yunnan Region Using BEMD Method.Journal of Geodesy and Geodynamics, 38(4):407-413(in Chinese with English abstract). http://d.old.wanfangdata.com.cn/Periodical/dkxbydz201804016 Zhang, J., Ma, Z.J., 2004.East-West Segmentation of the Tibetan Plateau and Its Implication.Acta Geologica Sinica, 78(2):218-227, 290(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dizhixb200402011 Zhang, W., Zhang, X. J., Tong, J., et al., 2018. Gravity and Magnetic Anomaly Characteristics and Its Geological Interpretation in Rizhao and Lianyungang Areas.Earth Science, 43(12):4490-4497 (in Chinese with English abstract). http://d.old.wanfangdata.com.cn/Periodical/dqkx201812017 Zhou, W.N., Zeng, Z.F., Du, X.J., et al., 2010.Gravity Anomaly Separation Based on Empirical Mode Decomposition.World Geology, 29(3):495-502(in Chinese with English abstract). http://d.old.wanfangdata.com.cn/OAPaper/oai_doaj-articles_0135354d8a9b9ca7f9c5e3608c072772 Zhu, Z. Y., Liu, G. F., 2016. Analysis of Potential Field Data and Its Application Based on Bi-dimensional Empirical Mode Decomposition. Progress in Geophysics, 31(2):882-892(in Chinese with English abstract). 陈建国, 肖凡, 常韬, 2011.基于二维经验模态分解的重磁异常分离.地球科学, 36(2):327-335. https://doi.org/10.3799/dqkx.2011.034 郭颖星, 王多君, 周永胜, 等, 2017.青藏高原南部花岗岩电导率研究及地球物理应用.中国科学:地球科学, 47(7):860-870. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=zgkx-cd201707008 贺日政, 高锐, 郑洪伟, 等, 2007.青藏高原中西部航磁异常的匹配滤波分析与构造意义.地球物理学报, 50(4):1131-1140. http://d.old.wanfangdata.com.cn/Periodical/dqwlxb200704020 孔祥儒, 王谦身, 1996.西藏高原西部综合地球物理与岩石圈结构研究.中国科学(D辑), (4):308-315. doi: 10.3321/j.issn:1006-9267.1996.04.004 滕吉文, 张洪双, 孙若昧, 等, 2011.青藏高原腹地东西分区和界带的地球物理场特征与动力学响应.地球物理学报, 54(10):2510-2527. doi: 10.3969/j.issn.0001-5733.2011.10.009 王成彬, 陈建国, 肖凡, 等, 2014.经验模态分解和独立分量分解在航磁数据处理中的应用.地质学刊, 38(4):623-629. doi: 10.3969/j.issn.1674-3636.2014.04.623 熊盛青, 周伏洪, 姚正煦, 等, 2007.青藏高原中西部航磁概查.物探与化探, 31(5):404-407. doi: 10.3969/j.issn.1000-8918.2007.05.005 薛典军, 姜枚, 吴良士, 等, 2006.青藏高原区域重磁异常的东西向分区及其构造地质特征.中国地质, 33(4):912-919. doi: 10.3969/j.issn.1000-3657.2006.04.021 杨文采, 侯遵泽, 于常青, 2015.青藏高原地壳的三维密度结构和物质运动.地球物理学报, 58(11):4223-4234. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqwlxb201511029 曾琴琴, 刘天佑, 2011.重、磁异常的经验模态分解及其在鄂东张福山铁矿勘探中的应用.地球物理学进展, 26(4):1409-1414. doi: 10.3969/j.issn.1004-2903.2011.04.036 张双喜, 陈超, 王林松, 等, 2015.二维经验模态分解及其在位场去噪和分离中的应用.地球物理学进展, 30(6):2855-2862. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqwlxjz201506053 张双喜, 陈兆辉, 王同庆, 等, 2018.利用二维经验模态分解提取川滇地区流动重力异常特征.大地测量与地球动力学, 38(4):407-413. http://d.old.wanfangdata.com.cn/Periodical/dkxbydz201804016 张进, 马宗晋, 2004.西藏高原西、中、东的分段性及其意义.地质学报, 78(2):218-227, 290. doi: 10.3321/j.issn:0001-5717.2004.02.011 张婉, 张玄杰, 佟晶, 等, 2018.日照-连云港地区重磁异常特征及其构造意义.地球科学, 43(12):4490-4497. http://earth-science.net/WebPage/Article.aspx?id=4072 周文纳, 曾昭发, 杜晓娟, 等, 2010.基于经验模态分解的重力异常分离.世界地质, 29(3):495-502. doi: 10.3969/j.issn.1004-5589.2010.03.019 朱振宇, 刘国峰, 2016.基于二维经验模态分解的位场数据分析及应用.地球物理学进展, 31(2):882-892. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqwlxjz201602052 -
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