中亚造山带东段岩石圈电性结构特征及其构造涵义

doi:10.19657/j.geoscience.1000-8527.2022.069

摘要/Abstract

摘要：

中亚造山带东段内蒙古中部地区一直是地球内部动力学和全球变化研究的热点地区。鉴于该地区的构造在理解中亚造山带的形成过程中起着重要作用,因此对该地区构造的研究具有重要意义。本文收集了中亚造山带东段一条长364 km的大地电磁测深(MT)剖面数据,该剖面西北起于内蒙古东乌旗内的国境线附近,向东南延伸,穿过北部造山带、索伦缝合带、南部造山带,在内蒙古翁牛特旗以西约30 km附近终止。根据数据的分析结果,对该剖面进行了二维反演。结果表明,剖面区段内岩石圈电性结构沿南北方向上整体表现为横向分块的特征。其中,北部造山带整体上以低阻为主要特征;索伦缝合带是整个剖面电性特征从低阻到高阻的过渡区;南部造山带整体上以高阻为主要特征。北部造山带的低阻特征表明该区域是不稳定的,可能是由古亚洲洋闭合后残留洋壳或者软流圈上升流引起的。索伦缝合带的电性结构特征表明该区域可能在缝合之后还发生了新的构造事件。南部造山带的高阻特征表明该区域基底是稳定的、“冷”的,且流体含量很低,电性结构的几何特征反映了该区域增厚的岩石圈。剖面所经过区域的电性结构特征表明,在西伯利亚板块与华北板块碰撞缝合之后研究区内可能还发生了诸如软流圈流体上升、岩石圈增厚等新的构造事件。此外,该区域的电性结构特征符合缝合带的特点,这为中亚造山带东段构造演化的连续增生模型提供了新的深部地球物理证据。

关键词: 大地电磁测深, 中亚造山带, 索伦缝合带, 构造演化

Abstract:

The eastern segment of the Central Asian Orogenic Belt (CAOB) in central Inner Mongolia has always been a hot research field in the Earth’s internal dynamics and global change. Tectonic study in this region is of great significance given its important role in understanding the CAOB formation. A 364 km-long magnetotelluric sounding (MT) profile in the eastern CAOB is collected in this study. The profile starts from the northwest near the national border in Dongwuqi of Inner Mongolia, and extends to the southeast through the Northern Orogenic Belt (NOB), Solonker Suture Zone (SSZ) and Southern Orogenic Belt (SOB), and terminates about 30 km west of Wengniuteqi of Inner Mongolia. Based on the data analysis results, 2D inversions were conducted on the dataset. Resulting model shows that the electrical structure of the lithosphere along the profile is characterized by NS-trending transverse blocking. The NOB is generally characterized by low resistivity; The SSZ is the transition zone of the electrical characteristics of the whole section from low to high resistivity; The SOB is mainly characterized by high resistivity. The low resistivity characteristics of NOB indicate that the region is unstable, which may be caused by the residual oceanic crust or asthenospheric upwelling after the Paleo-Asian Ocean closure. The SSZ electrical structure indicates that a new tectonic event may have occurred after the suturing. The high resistivity characteristics of the SOB indicate that the basement is stable and “cold”, and the fluid content is very low, with the geometric characteristics of the electrical structure reflecting the thickened lithosphere. The regional electrical structure characteristics along the profile indicate that new tectonic events, such as asthenospheric fluid ascent and lithospheric thickening, may have occurred after the collision between the Siberian and North China Cratons. In addition, the regional electrical structure is consistent with the suture zone characteristics, which provides new deep geophysical evidence for the continuous accretion model of tectonic evolution in the eastern CAOB.

Key words: magnetotellurics, Central Asian Orogenic Belt, Solonker suture zone, tectonic evolution

中图分类号:

P631.3

李波, 金胜, 叶高峰, 魏文博. 中亚造山带东段岩石圈电性结构特征及其构造涵义[J]. 现代地质, 2023, 37(01): 15-30.

LI Bo, JIN Sheng, YE Gaofeng, WEI Wenbo. Lithospheric Electrical Structure of Eastern Segment of Central Asian Orogenic Belt and Its Tectonic Implications[J]. Geoscience, 2023, 37(01): 15-30.

图/表 14

图1 研究区大地构造简图(修改自文献[13-14]) SC.西伯利亚板块; TC.塔里木板块; NCC.华北板块; IC.印度板块;SCC.华南板块;CAOB.中亚造山带;红色圆点为宽频MT测点;CHSP.地震折射和广角反射剖面[13,15];DMT与YMT为MT剖面

Fig.1 Tectonic subdivision of the study area (modified from refs.[13-14])

图2 研究区地质简图(修改自文献[13]; 二连盆地资料引自文献[16])

Fig.2 Geological map of the study area (modified from ref.[13]; data of Erlian Basin from ref.[16])

图3 典型MT测点测深曲线数据已旋转至构造走向N45°E:(a)3272点,位于乌里雅斯太陆块;(b)3327点,位于贺根山增生杂岩带;(c)3405点,位于宝力道弧增生杂岩带;(d)3470点,位于索伦缝合带;(e)3519点,位于温都尔庙俯冲-增生杂岩带;(f)3637点,位于白乃庙弧

Fig.3 Examples of MT sounding curves

图4 相位张量椭圆示意图

Fig.4 Schematic diagram of phase tensor ellipse

图5 MT剖面相位张量分析图

Fig.5 Phase tensor maps of MT profile

图6 北部造山带(NOB)、索伦缝合带(SSZ)以及南部造山带(SOB)构造走向分析结果图(0.1~1 s, 1~10 s, 10~100 s, 100~1000 s)

Fig.6 Rose diagrams of strike analysis results (0.1~1 s, 1~10 s, 10~100 s, 100~1000 s) for the NOB, SSZ and SOB

图7 采用了不同的极化模式组合数据的MT剖面二维反演结果对比图 (a) TE, RMS=10.4880; (b) TE+Hz, RMS=6.2506; (c) TE+TM, RMS=8.2160; (d) TM, RMS=2.0638; (e) TM+Hz, RMS=1.8648; (f) TE+TM+Hz, RMS=5.6441

Fig.7 MT profile 2D inversion comparison diagrams, using different polarization mode combination data

图8 剖面不同正则化因子反演得到的模型粗糙度与拟合误差曲线L

Fig.8 L-curve of roughness and RMS values for the profile with different τ

图9 TM(a)和Hz(b)的实测数据与响应数据拟断面图

Fig.9 Pseudosection of observed and modeled TM (a) and Hz (b) data

图10 MT剖面二维电性结构模型

Fig.10 2D electrical structure model of MT profile

图11 初始二维反演模型和多个正演模型沿剖面的RMS分布(a)初始二维反演模型(b)和限制不同深度的正演模型(c)

Fig.11 RMS distribution along the profile (a) for the original 2D inversion model (b) and several forward modeling models (c)

图12 初始二维反演模型和多个正演模型沿剖面的RMS分布(a)初始二维反演模型(b)和限制不同深度的正演模型(c)

Fig.12 RMS distribution along the profile (a) for the original 2D inversion model (b) and several forward modeling models (c)

图13 MT剖面二维电性结构模型解释图 (a)沿剖面地形图; (b)根据图2简化的区域地质单元; (c)根据图1(b)简化的大地构造单元; (d)二维电阻率模型;UB.乌里雅斯太陆块;HB.贺根山增生杂岩带; BLB.宝力道弧增生杂岩带;SSZ.索伦缝合带;OSB.温都尔庙俯冲-增生杂岩带;BNB.白乃庙弧;Moho(莫霍面)深度据文献[13]

Fig.13 Tectonic interpretation of 2D MT inversion model

图14 中亚造山带东段演化的连续增生模型(修改自文献[14,63])

Fig.14 Continuous accretion model describing the tectonic evolution of the eastern CAOB (modified from refs.[14,63])

参考文献 65

[1]	DEMOUX A, KRÖNER A, BADARCH G, et al. Zircon ages from the Baydrag Block and the Bayankhongor ophiolite zone: time constraints on late Neoproterozoic to Cambrian subduction- and accretion-related magmatism in Central Mongolia[J]. Journal of Geology, 2009, 117: 377-397. DOI URL
[2]	GLORIE S, DE G J, BUSLOV M M, et al. Formation and Palaeozoic evolution of the Gorny-Altai-Altai-Mongolia suture zone (South Siberia): zircon U/Pb constraints on the igneous record[J]. Gondwana Research, 2011, 20: 465-484. DOI URL
[3]	KHAIN E V, BIBIKOVA E V, SALNIKOVA E B, et al. The Palaeo-Asian ocean in the Neoproterozoic and Early Palaeozoic: new geochronologic data and palaeotectonic reconstructions[J]. Precambrian Research, 2003, 122 (1/ 4): 329-358. DOI URL
[4]	KRÖNER A, DEMOUX A, ZACK T, et al. Zircon ages for a felsic volcanic rock and arc-related early Palaeozoic sediments on the margin of the Baydrag microcontinent, central Asian orogenic belt, Mongolia[J]. Journal of Asian Earth Sciences, 2011, 42:1008-1017. DOI URL
[5]	LI J Y. Permian geodynamic setting of Northeast China and adjacent regions: closure of the Paleo-Asian Ocean and subduction of the Paleo-Pacific Plate[J]. Journal of Asian Earth Sciences, 2006, 26: 207-224. DOI URL
[6]	SENGÖR A M C, NATAL B A, BURTMAN V S. Evolution of the Altaidtectonic collage and Palaeozoic crustal growth in Eurasia[J]. Nature, 1993, 364: 299-307. DOI
[7]	WINDLEY B. The tectonic evolution of Asia[J]. Geophysical Journal International, 2018, 129(1): 219-219. DOI URL
[8]	XIAO W J, WINDLEY B F, HAO J, et al. Accretion leading to collision and the Permian Solonker suture, Inner Mongolia, China: termination of the Central Asian orogenic belt[J]. Tectonics, 2003, 22: 1484-1505.
[9]	XIAO W J, HUANG B, HAN C, et al. A review of the western part of the Altaids: A key to understanding the architecture of accretionary orogens[J]. Gondwana Research, 2010, 18: 253-273. DOI URL
[10]	WINDLEY B F, ALEXEIEV D, XIAO W, et al. Tectonic models for accretion of the Central Asian Orogenic Belt[J]. Journal of the Geological Society, 2007, 164: 31-47. DOI URL
[11]	DOBRETSOV N L, BUSLOV M M. Late Cambrian-Ordovician tectonics and geodynamics of Central Asia[J]. Russian Geology and Geophysics, 2007, 48: 1-12. DOI URL
[12]	ROJAS A Y, KRÖNER A, DEMOUX A, et al. Detrital and xenocrystic zircon ages from Neoproterozoic to Palaeozoic arc terranes of Mongolia: Significance for the origin of crustal fragments in the Central Asian Orogenic Belt[J]. Gondwana Research, 2012, 19: 751-763. DOI URL
[13]	ZHANG S H, GAO R, LI H, et al. Crustal structures revealed from a deep seismic reflection profile across the Solonker suture zone of the Central Asian Orogenic Belt, northern China: An integrated interpretation[J]. Tectonophysics, 2014, 612: 26-39.
[14]	XIAO W J, WINDLEY B F, SUN S, et al. A tale of amalgamation of three Permo-Triassic collage systems in central Asia: Oroclines, sutures, and terminal accretion[J]. Annual Review of Earth and Planetary Sciences, 2015, 43: 477-507. DOI URL
[15]	LI W, KELLER G R, GAO R, et al. Crustal structure of the northern margin of the North China Craton and adjacent region from SinoProbe02 North China seismic WAR/R experiment[J]. Tectonophysics, 2013, 606: 116-126. DOI URL
[16]	XU W, HUANG S, ZHANG J, et al. Present-day geothermal regime of the Uliastai Depression, Erlian Basin, North China[J]. Energy Exploration & Exploitation, 2019, 37: 770-786.
[17]	汤双立, 颜丹平, 汪昌亮, 等. 华南雪峰山薄皮-厚皮构造转换过程:来自桑植—安化剖面的证据[J]. 现代地质, 2011, 25(1): 22-30.
[18]	张磊, 白凌燕, 蔡向民, 等. 北京南口—孙河断裂北西段综合物探剖面定位及其活动性研究[J]. 现代地质, 2014, 28(1): 234-242.
[19]	罗旭, 毛星, 魏文博, 等. 大地电磁数据三维反演技术在隐伏断裂勘察中的应用:以郯庐断裂宿迁段为例[J]. 现代地质, 2016, 30(3): 587-596.
[20]	MARTYN U, STÉPHANE R. Mapping the distribution of fluids in the crust and lithospheric mantle utilizing geophysical methods[R]. Metasomatism and the Chemical Transformation of Rock, 2013, 13: 535-598.
[21]	BADARCH G, CUNNINGHAM W D, WINDLEY B F. A new terrane subdivision for Mongolia: implications for the Phanerozoic crustal growth of Central Asia[J]. Journal of Asian Earth Sciences, 2002, 21: 87-110. DOI URL
[22]	TOMURTOGOO O, WINDLEY B F, KRÖNER A, et al. Zircon age and occurrence of the Adaatsag ophiolite and Muron shear zone, central Mongolia: constraints on the evolution of the Mongol-Okhotsk ocean, suture and orogen[J]. Journal of the Geological Society, 2005, 162: 125-134. DOI URL
[23]	WILHEM C, WINDLEY B F, STAMPFLI G M. The Altaids of Central Asia: a tectonic and evolutionary innovative review[J]. Earth Science Reviews, 2012, 113 (3/4) : 303-341. DOI URL
[24]	JIAN P, LIU D, KRÖNER A, et al. Time scale of an early to mid-Paleozoic orogenic cycle of the long-lived Central Asian Orogenic Belt, Inner Mongolia of China: implications for continental growth[J]. Lithos, 2008, 101: 233-259. DOI URL
[25]	CHEN B, JAHN B M, TIAN W. Evolution of the Solonker suture zone: constraints from zircon U-Pb ages, Hf isotopic ratios and whole-rock Nd-Sr isotope compositions of subduction- and collision-related magmas and forearc sediments[J]. Journal of Asian Earth Sciences, 2009, 34: 245-257. DOI URL
[26]	JIAN P, KRÖNER A, WINDLEY B F, et al. Carboniferous and Cretaceous mafic-ultramafic massifs in Inner Mongolia (China): a SHRIMP zircon and geochemical study of the previously presumed integral “Hegenshan ophiolite”[J]. Lithos, 2012, 142/143: 48-66. DOI URL
[27]	XIAO W J, KRÖNER A, WINDLEY B. Geodynamic evolution of Central Asia in the Paleozoic and Mesozoic[J]. International Journal of Earth Sciences, 2009, 98: 1185-1188. DOI URL
[28]	XU B, CHARVET J, CHEN Y, et al. Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[J]. Gondwana Research, 2013, 23(4): 1342-1364. DOI URL
[29]	MOORKAMP M. Comment on ‘The magnetotelluric phase tensor’ by T. Grant Caldwell, Hugh M. Bibby and Colin Brown[J]. Geophysical Journal International, 2007, 171: 565-566. DOI URL
[30]	MCNEICE G W, JONES A G. Multisite, multifrequency tensor decomposition of magnetotelluric data[J]. Geophysics, 2001, 66(1): 158-173. DOI URL
[31]	RODI W, MACKIE R L. Nonlinear conjugate gradients algorithm for 2-D magnetotelluric inversion[J]. Geophysics, 2001, 66(1): 174-187. DOI URL
[32]	蔡军涛, 陈小斌. 大地电磁资料精细处理和二维反演解释技术研究(二):反演数据极化模式选择[J]. 地球物理学报, 2010, 53(11): 2703-2714.
[33]	LEDO J, JONES A G. Upper mantle temperature determined from combining mineral composition, electrical conductivity laboratory studies and magnetotelluric field observations: Application to the intermontane belt, Northern Canadian Cordillera[J]. Earth and Planetary Science Letters, 2005 (1/2): 258-268.
[34]	BOOKER J R, FAVETTO A, POMPOSIELLO M C. Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina[J]. Nature, 2004, 429: 399-403. DOI
[35]	WANNAMAKER P E, JIRACEK G R, STODT J A, et al. Fluid generation and pathways beneath an active compressional orogen, the New Zealand Southern Alps, inferred from magnetotelluric data[J]. Journal of Geophysical Research Atmospheres, 2002, 107(6): 1-21.
[36]	FARQUHARSON C G, OLDENBURG D W. A comparison of automatic techniques for estimating the Regularisation parameter in non-linear inverse problems[J]. Geophysical Journal International, 2004, 156(3): 411-425. DOI URL
[37]	HU Y C, LI T L, FAN C S, et al. Three-dimensional tensor controlled-source electromagnetic modeling based on the vector finite-element method[J]. Applied Geophysics, 2015, 12(1): 34-56.
[38]	PARKINSON W. Directions of rapid geomagnetic fluctuations[J]. Geophysical Journal of the Royal Astronomical Society, 1959, 2(1): 1-14.
[39]	WIESE H. Geomagnetische Tiefentellurik Teil II: Die Streichrichtung der Untergrund strukturen des elektrischen widerstandes, erschlossen aus geomagnetischen variationen[J]. Geofisica Pura E Applicata, 1962, 52(1):83-103.
[40]	陈小斌, 赵国泽, 詹艳, 等. 磁倾子矢量的图示分析及其应用研究[J]. 地学前缘, 2004, 11(4): 626-636.
[41]	田郁, 胡祥云, 乐彪. 倾子在地球物理断裂构造解释中的应用[J]. 物探与化探, 2018, 42(6): 1237-1244.
[42]	BADARCH G, CUNNINGHAM W D, WINDLEY B F. A new terrane subdivision for Mongolia: implications for the Phanerozoic crustal growth of Central Asia[J]. Journal of Asian Earth Sciences, 2002, 21: 87-110. DOI URL
[43]	张玉清, 许立权, 康小龙, 等. 内蒙古东乌珠穆沁旗京格斯台碱性花岗岩年龄及意义[J]. 中国地质, 2009, 36(5): 988-995.
[44]	MIAO L, FAN W, LIU D, et al. Geochronology and geochemistry of the Hegenshan ophiolitic complex: implications for late-stage tectonic evolution of the Inner Mongolia-Daxinganling Orogenic Belt, China[J]. Journal of Asian Earth Sciences, 2008, 32: 348-370. DOI URL
[45]	NOZAKA T, LIU Y. Petrology of the Hegenshan ophiolite and its implication for the tectonic evolution of northern China[J]. Earth Planetary Science Letters, 2002, 202: 89-104. DOI URL
[46]	车自成, 罗金海, 刘良. 中国及邻区区域大地构造学[M]. 北京: 科学出版社, 2011: 1-466.
[47]	王荃, 刘雪亚, 李锦轶. 中国内蒙古中部的古板块构造[J]. 地球学报, 1991, 12(1):4-18.
[48]	LI S, UNSWORTH M J, BOOKER J R, et al. Partial melt or aqueous fiuid in the mid-crust of Southern Tibet? Constraints from INDEPTH magnetotelluric data[J]. Geophysical Journal International, 2003, 153(2) : 289-304. DOI URL
[49]	UNSWORTH M J, JONES A G, WEI W, et al. Crustal rheology of the Himalaya and southern Tibet inferred from magnetotelluric data[J]. Nature, 2005, 438: 78-81. DOI
[50]	WANG Y, CHENG S H. Lithospheric thermal structure and rheology of the eastern China[J]. Journal of Asian Earth Sciences, 2012, 47: 51-63. DOI URL
[51]	FROST B R, BUCHER K. Is water responsible for geophysical anomalies in the deep continental crust? A petrological perspective[J]. Tectonophysics, 1994, 231(4): 293-309. DOI URL
[52]	YOSHINO T, NORITAKE F. Unstable graphite films on grain boundaries in crustal rocks[J]. Earth and Planetary Science Letters, 2011, 306(3/4) : 186-192. DOI URL
[53]	SUN Y, DONG S, ZHANG H, et al. 3D thermal structure of the continental lithosphere beneath China and adjacent regions[J]. Journal of Asian Earth Sciences, 2013, 62: 697-704. DOI URL
[54]	XU Y. Diachronous lithospheric thinning of the North China Craton and formation of the Daxin’anling-Taihangshan gravity lineament[J]. Lithos, 2007, 96: 281-298. DOI URL
[55]	RAO C K, JONES A G, MAX M. The geometry of the Iapetus Suture Zone in central Ireland deduced from a magnetotelluric study[J]. Physics of the Earth and Planetary Interiors, 2007, 161: 134-141. DOI URL
[56]	DONG Z Y, TANG J, UNSWORTH M, et al. Electrical resistivity structure of the upper mantle beneath Northeastern China: Implications for rheology and the mechanism of craton destruction[J]. Journal of Asian Earth Sciences, 2015, 100: 115-131. DOI URL
[57]	YE G F, UNSWORTH M, WEI W B, et al. The lithospheric structure of the Solonker suture zone and adjacent areas: Crustal anisotropy revealed by a high-resolution magnetotelluric study[J]. Journal of Geophysical Research: Solid Earth, 2019, 124: 1142-1263. DOI URL
[58]	王鸿祯, 何国琦, 张世红. 中国与蒙古之地质[J]. 地学前缘, 2006, 13(6): 1-12.
[59]	CHEN B, JAHN B M, WILDE S, et al. Two contrasting Paleo-zoic magmatic belts in northern Inner Mongolia, China: Petrogenesis and tectonic implications[J]. Tectonophysics, 2000, 328: 157-182. DOI URL
[60]	LIU S W, SANTOSH M, WANG W, et al. Zircon U-Pb chrono-logy of the Jianping Complex: Implications for the Precambrian crustal evolution history of the northern margin of North China Craton[J]. Gondwana Research, 2011, 20:48-63. DOI URL
[61]	韩江涛, 袁天梦, 刘文玉, 等. 西伯利亚板块与华北克拉通碰撞带地电结构及对深部缝合边界的讨论[J]. 地球物理学报, 2019, 62(3): 1159-1171.
[62]	MOSSAKOVSKY A, RUZHENTSEV S V, SAMYGIN S G, et al. Central Asian fold belt: geodynamic evolution and history of formation[J]. Geotectonics, 1993, 6: 3-33.
[63]	MA X H, CHEN B, YANG M C. Magma mixing origin for the Aolunhua porphyry related to Mo-Cu mineralization, eastern Central Asian Orogenic Belt[J]. Gondwana Research, 2013, 25(3): 1-20. DOI URL
[64]	PAN S K, ZHENG J P, CHU L L, et al. Coexistence of the moderately refractory and fertile mantle beneath the eastern Central Asian Orogenic Belt[J]. Gondwana Research, 2013, 23(1): 176-189. DOI URL
[65]	ZHANG Z, ZHANG H F, SHAO J A, et al. Mantle upwelling during Permian to Triassic in the northern margin of the North China Craton: Constraints from southern Inner Mongolia[J]. Journal of Asian Earth Sciences, 2014, 79: 112-129. DOI URL