| Citation: | JIANG Shoujin, LÜ Xiaochun, LI Huaiyuan, HU Junfeng, CHEN Yongling. 2024. Application of audio magnetotelluric method in the investigation of complex structural zone:A case study of the Bamei section of Xinben fault zone in eastern Xizang. Sedimentary Geology and Tethyan Geology, 44(4): 897-908. doi: 10.19826/j.cnki.1009-3850.2024.10006 |
The Xinben fault zone is a regional fault zone with a strike of northwest-southeast direction in the Boshura Ridge magmatic arc of the eastern Qingzang (Xizang) Plateau, superimposed by multiple tectonic activity, with a complex geologic structure and a variety of tectonic types. Through geologic investigations, it was previously considered to be only a few hundred meters in size and with a controversy of fault nature over the compressive-torsional and thrust-nappe. This paper applies the audio magnetotelluric (AMT) method to investigate the Bamei section of the Xinben fault zone. After the time-frequency domain denoising, static correction, and polarization pattern recognition for the AMT data, this paper uses nonlinear conjugate gradient (NLCG) inversion technology to obtain high-precision two-dimensional electrical profiles, carries out comprehensive geologic-geophysical interpretation, and establishes a geologic model for the bathymetric profiles. Combined with the deep electrical structure of the bathymetric section, the regional tectonic background and the shallow tectonic phenomena, it was found that the fault zone in the Bamei section is a compressive strike-slip tectonic zone with a width of 7.2 km, comprised of a series of ductile shear zones and high-angle strike-slip faults. The fault zone has a tectonic characteristics of early ductile shear superimposed by the later extrusion of left strike-slip on the shallow surface.
| [1] | 陈克强,高振家,李龙,等,2003. 有关深部地质填图和立体地质填图的几个问题[J]. 地质通报, 22(11-12):984 − 990. Chen K Q,Gao Z J,Li L,et al.,2003. Programs concerning deep geological mapping and geological stereomapping[J]. Geological Bulletin of China, 22(11-12):984 − 990 (in Chinese with English abstract). |
| [2] | Chen L S,Wang G E,1990. Magnetotelluric sounding[M]. Beijing:Geology Press. |
| [3] | 董树文,李廷栋,陈言华,等,2012. 我国深部探测技术与实验研究进展综述[J]. 地球物理学报,55(12):3884 − 3901. Dong S W,Li T D,Chen Y H,et al.,2012. Review of the progress of deep exploration technology and experimental research in China[J]. Chinese Journal of Gepohysics,55(12):3884 − 3901 (in Chinese with English abstract). |
| [4] | 董树文, 李廷栋, 陈言华, 等, 2012. 我国深部探测技术与实验研究进展综述[J]. 地球物理学报, 55(12): 3884 − 3901. doi: 10.6038/j.issn.0001-5733.2012.12.002 Egbert G D,Mackie J R,1986. Robust estimation of geomagnetic transfer functins[J]. Geophysical Journal of the Royal Astronomical Society,87(1):173 − 194. doi: 10.6038/j.issn.0001-5733.2012.12.002 |
| [5] | 冯兵,李建国,赵斌,等,2014. 音频大地电磁法在南岭十都−赣县矿集区银坑不范区深部矿产资源探测中的应用[J]. 地质学报,88(4):669 − 67. doi: 10.1111/j.1365-246X.1986.tb04552.x Feng B,Li J G,Zhao B,et al.,2014. Application of audio frequency magnetotelluric method in the exploration of deep mineral resources in Yinkeng non-standard area of Nanling Shidu - Ganxian ore concentration area[J]. Acta Geologica Sinica,88(4):669 − 67 (in Chinese with English abstract). doi: 10.1111/j.1365-246X.1986.tb04552.x |
| [6] | 王桥,杨剑,唐发伟,等,2023. 碳酸盐岩深覆盖区隐伏岩溶构造的音频大地电磁探测:以云南大关地区为例[J]. 沉积与特提斯地质,43(4):770 − 778. Wang Q,Yang J,Tang F W,et al.,2023. Audio magnetotelluric detection of hidden karst in deep carbonatecoverage area:A case study of Daguan area in Yunnan province,China[J]. Sedimentary Geology and Tethyan Geology,43(4):770 − 778 (in Chinese with English abstract). |
| [7] | 高天,何国丽,周安昌,等,2019. 基于音频大地测深法研究乌拉嘎断裂[J]. 地球物理学进展,34(2):545 − 553. Gao T,He G L,Zhou A C,et al.,2019. Study on the Wulaga fault by Audio Magnetotelluric(AMT)[J]. Progress in Geophysics,34(2):545 − 553 (in Chinese with English abstract). |
| [8] | 胡祥云,霍光谱,高锐,等,2013. 大地电磁各向异性二维模拟及实例分析[J]. 地球物理学报,56(12):4268 − 4277. doi: 10.6038/pg2019CC0039 Hu X Y,Huo G P,Gao R,et al.,2013. The magnetotelluric anisotropic 2D simulation and case analysis[J]. Chinese Journal of Geophysics,56(12):4268 − 4277 (in Chinese with English abstract). doi: 10.6038/pg2019CC0039 |
| [9] | 蒋首进,陈永凌,李怀远,等,2023. 藏东南冻错曲塘布段冰碛物电阻率特征[J]. 物探与化探,47(1):73 − 80. doi: 10.6038/cjg20131229 Jiang S J,Chen Y L,Li H Y,et al.,2023. Resistivity of moraine deposits in the Tangbu section Dongcuoqu southeastern Xizang[J]. Geophysical and Geochemical Exploration,47(1):73 − 80 (in Chinese with English abstract). doi: 10.6038/cjg20131229 |
| [10] | 刘战,2019. 音频大地电磁法在探测断层发育区中的应用[J]. 工程地球物理学报,16(5):730 − 736. Liu Z,2019. Application of audio frequency magnetotelluric method in detecting fault development areas[J]. Journal of Engineering Geophysics,16(5):730 − 736 (in Chinese with English abstract). |
| [11] | 苗景春,阮帅,张悦,2013. 音频大地电磁测深法对正、逆断层的精细解释[J]. 物探与化探,4(19):1000 − 8918. doi: 10.3969/j.issn.1672-7940.2019.05.029 Miao J C,Ruan S,Zhang Y,2013. Fine interpretation of normal and reverse faults by audio magnetotelluric sounding[J]. Geophysical and Geochemical Exploration,4(19):1000 − 8918 (in Chinese with English abstract). doi: 10.3969/j.issn.1672-7940.2019.05.029 |
| [12] | 闵刚,王绪本,张旭,等,2017. AMT法在四川广元宝轮地区中浅部地质调查中的应用[J]. 地质学报,91(3):690 − 702. Min G,Wang X B,Zhang X,et al.,2017. Application of AMT method in the shallow and middle geological survey of Baolun area,Guangyuan,Sichuan[J]. Acta Geologica Sinica,91(3):690 − 702 (in Chinese with English abstract). |
| [13] | 潘桂棠,王立全,尹福光,等,2022. 青藏高原形成演化研究回顾、进展与展望[J]. 沉积与特提斯地质,42(2):151 − 175. doi: 10.3969/j.issn.0001-5717.2017.03.015 Pan G T,Wang L Q,Yin F G,et al.,2022. Reserches on geological tectonic evolution of Xizang Plateau:A review,recent advances,and directions in the future[J]. Sedimentary Geology and Tethyan Geology,42(2):151 − 175 (in Chinese with English abstract). doi: 10.3969/j.issn.0001-5717.2017.03.015 |
| [14] | 潘桂棠,王立全,耿全如,等,2020. 班公湖—双湖—怒江—昌宁—孟连对接带时空结构:特提斯大洋地质及演化问题[J]. 沉积与特提斯地质,40(3):1 − 19. Pan G T,Wang L Q,Geng Q R,et al.,2020. Space-time structure of the Bangonghu-Shuanghu-Nujiang-Changning-Menglian Mega-suture zone:A discussion on geology and evolution of the Tethys Ocean[J]. Sedimentary Geology and Tethyan Geology,40(3):1 − 19 (in Chinese with English abstract). |
| [15] | 潘桂堂,任飞,尹福光,等,2020. 洋板块地质与川藏铁路工程地质关键区带[J]. 地球科学,45(7):2293 − 2304. Pan G T,Ren F,Yin F G,et al.,2020. Key zones of oceanic plate geology and Sichuan-Xizang Railway project[J]. Earth Science,45(7):2293 − 2304 (in Chinese with English abstract). |
| [16] | 潘桂堂, 任飞, 尹福光, 等, 2020. 洋板块地质与川藏铁路工程地质关键区带[J]. 地球科学, 45(7): 2293 − 2304. Pan G T,Wang L Q,Zhang W P,et al.,2013. Tectonic map and specification of Qinghai-Xizang Plateau and its adjacent areas (1∶1 500 000)[M]. Beijing:Geology Press. |
| [17] | Pan G T,Xiao Q H,Yin F G,et al.,2017. Great geological structure of China[M]. Beijing:Geology Press. |
| [18] | Pu J C,2002. China glacier catalogue 9-10 Lancang River Basin Nujiang River Basin[M]. Xi'an:Xi'an Map Publishing House. |
| [19] | Rodiw,Mackie R L,2001. Nonlinear conjugate gradients algorithm for 2D magnetotelluric inversion[J]. Geophysics,66(1):174 − 187. |
| [20] | 汤井田,任政勇,周聪,等,2015. 浅部频率域电磁勘探方法综述[J]. 地球物理学报,58(8):2681 − 2705. Tang J T,Ren Z Y,Zhou C,et al.,2015. Overview of shallow frequency domain electromagnetic exploration methods[J]. Chinese Journal of Geophysics,58(8):2681 − 2705 (in Chinese with English abstract). |
| [21] | 杨菱,石永辉,1990. 复杂地区大地电磁测深曲线的性质及资料解释问题综述[J]. 地球科学,15(s):69 − 78. Yang L,Shi Y H,1990. Overview of the characteristics of MT curves and the interpretation of MT data in complex areas[J]. Earth Science,15(s):69 − 78 (in Chinese with English abstract). |
| [22] | 李兆令,刘宝江,代小强,等,2023. 基于综合地球物理方法的隐伏线性构造探测[J]. 云南大学学报:自然科学版,45(S1):102 − 108. Li Z L,Liu B J,Dai X Q,et al.,2023. Concealed linear structure detection based on integrated geophysical method[J]. Journal of Yunnan University:Natural Sciences Edition,45(S1):102 − 108 (in Chinese with English abstract). |
| [23] | 王彬,刘伟祖,2018. 复杂地质模型音频大地电磁反演研究[J]. 工程地球物理学报,15(6):780 − 787. doi: 10.1190/1.1444893 Wang B,Liu W Z,2018. Model reserch of audio magnetotelluric in complex geological conditions[J]. Chinese Journal of Engineering Geophysics,15(6):780 − 787 (in Chinese with English abstract). doi: 10.1190/1.1444893 |
| [24] | 杨文采,徐义贤,张罗磊,等,2015. 塔里木地体大地电磁调查和岩石圈二维结构[J]. 地质学报,89(7):1161 − 1151. doi: 10.6038/cjg20150807 Yang W C,Xu Y X,Zhang L L,et al.,2015. The magnetotelluric survey of the Tarim terrane and the two-dimensional structure of the lithosphere[J]. Acta Geologica Sinica,89(7):1161 − 1151 (in Chinese with English abstract). doi: 10.6038/cjg20150807 |
| [25] | 叶涛,陈小斌,严良俊,2013. 大地电磁资料精细处理和二维反演技术研究[J]. 地球物理学报,56(10):3596 − 3606. Ye T,Chen X B,Yan L J,2013. Refined techniques for data processing and 2D inversion in magnetotelluric[J]. Chinese Journal of geophysics,56(10):3596 − 3606 (in Chinese with English abstract). |
| [26] | 詹艳,赵国泽,王立凤,等,2014. 西秦岭与南北构造带交汇区深部电性结构特征[J]. 地球物理学报,57(8):2594 − 2607. Zhan Y,Zhao G Z,Wang L F,et al.,2014. Characteristics of deep electrical structure in the intersection area of the West Qinling and the north-south tectonic belt[J]. Chinese Journal of Gepohysics,57(8):2594 − 2607 (in Chinese with English abstract). |
| [27] | 朱庆俊,李凤哲,王璇,2009. AMT静态效应和对导电薄层分辨能力的正演模拟[J]. 物探与化探,33(2):207 − 211. Zhu Q J,Li F Z,Wang X,2009. AMT static effects and forward simulation of the ability to resolve conductive thin layers[J]. Geophysical and Geochemical Exploration,33(2):207 − 211 (in Chinese with English abstract). |
| [28] | 陈乐寿,王光愕,1990. 大地电磁测深法[M]. 北京:地质出版社. Yang W C, Xu Y X, Zhang L L, et al., 2015. The magnetotelluric survey of the Tarim terrane and the two-dimensional structure of the lithosphere[J]. Acta Geologica Sinica, 89(7): 1161 − 1151. |
| [29] | 潘桂棠,王立全,张万平,等,2013. 青藏高原及邻区大地构造图及说明书(1∶1 500 000)[M]. 北京:地质出版社. doi: 10.6038/cjg20131034 Ye T, Chen X B, Yan L J, 2013. Refined techniques for data processing and 2D inversion in magnetotelluric[J]. Chinese Journal of geophysics, 56(10): 3596 − 3606. doi: 10.6038/cjg20131034 |
| [30] | 潘桂棠,肖庆辉,尹福光,等,2017. 中国大地质构造[M]. 北京:地质出版社. doi: 10.6038/cjg20140819 Zhan Y, Zhao G Z, Wang L F, et al., 2014. Characteristics of deep electrical structure in the intersection area of the West Qinling and the north-south tectonic belt[J]. Chinese Journal of Gepohysics, 57(8): 2594 − 2607. doi: 10.6038/cjg20140819 |
| [31] | 蒲健辰,2002. 中国冰川目录9-10澜沧江流域怒江流域[M]. 西安:西安地图出版社. Zhu Q J, Li F Z, Wang X, 2009. AMT static effects and forward simulation of the ability to resolve conductive thin layers[J]. Geophysical and Geochemical Exploration, 33(2): 207 − 211. |
The tectonic background map of the study area (a,according to Pan and Xiao,2017) and geological sketch map of the study area (b)
The measured profile of rock mass of Xinben fault structure
Outcrop characteristics of the Xinben fault zone
The measured profile of rock mass of Baqu fault structure
The location map of acquisition point for audio magnetotelluric data
Comparison of time domain interception and frequency domain Robust estimation of typical bathymetry points
Comparison of the effect before and after static correction of sounding profile
Curve diagrams of audio magnetotelluric single point sounding
Convergence curve of the 2D backcalculation error of the NLCG for TM data
2D inversion geoelectric model of audio magnetotelluric sounding profile
Interpretation results for audio magnetotelluric sounding profile
3D structural model of the Xinben fault zone