大别─苏鲁碰撞造山带的地震层析成像研究──岩石圈三维速度结构
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摘要
对包含大别－苏鲁碰撞造山带在内的东经 １１２°－１２４°，北纬２８°－３９°区域进行地 震层析成像研究，重建其地壳及上部地幔的三维速度图像．结果表明：造山带岩石圈速度横 向不均匀性显著；大别造山带以商城－麻城断裂为界，东侧的大别地块与西侧红安地块在地 壳速度上是两个不同的速度块体；中地壳 １５—２５ｋｍ深度范围内存在低速带，与伸展滑脱构造 有关；南、北大别构造单元之下，莫霍面下凹，地壳内发育了速度为６．５－６．６ｋｍ／ｓ、向北倾斜的 相对高速体，与超高压变质岩体相对应；在大别－苏鲁造山带下方的上部地幔中存在向北倾 斜的板片状高速体，结合已有地质、地球化学证据推测，它是三叠纪俯冲的扬子地块的残留 体；俯冲板片在深部发生了断离．本文利用地震层析成像方法揭示的造山带岩石圈速度结构 细节，对研究与地表地质有关的地球动力学无疑是十分重要的．
The 3-D velocity structures of the crust and upper mantle beneath the region of 112° - 124° E, 28°- 39° N including the Dabie-Sulu orogenic belt are reconstructed by using seismic tomography. The results demonstrate that a significant lateral heterogeneity of velocity structures exists in the crust and upper mantle beneath the Dabie orogenic belt and a low velocity layer in the middle crust corresponds to extensional and nappe structures. Beneath the southern and northern bole tectonic units, the Moho depresses and a north-dipping high-velocity block, which corresponds to the ultralhigh-pressure metamorphic rocks, range from 6.5 to 6.6 km/s, was developed in the crust. In the uppermost mantle beneath the orogenic belt was developed the north-dipping high-velocity slab. Taking into account of geological and geochemistrical data. we inferred that the high--velocity slab is the remnants of ancient subducted Yangtze block. Seismic tomography reveals that the subducted Yangtze ancient block was broken off. In this paper we present tomographic images of the lithospheric velocity structure in details under the Debie-Sulu orogenic belt that such structures may be useful in. associating geodynamic to surface--tectonic processes and is important in study of ancient orogenic belt.
The 3-D velocity structures of the crust and upper mantle beneath the region of 112° - 124° E, 28°- 39° N including the Dabie-Sulu orogenic belt are reconstructed by using seismic tomography. The results demonstrate that a significant lateral heterogeneity of velocity structures exists in the crust and upper mantle beneath the Dabie orogenic belt and a low velocity layer in the middle crust corresponds to extensional and nappe structures. Beneath the southern and northern bole tectonic units, the Moho depresses and a north-dipping high-velocity block, which corresponds to the ultralhigh-pressure metamorphic rocks, range from 6.5 to 6.6 km/s, was developed in the crust. In the uppermost mantle beneath the orogenic belt was developed the north-dipping high-velocity slab. Taking into account of geological and geochemistrical data. we inferred that the high--velocity slab is the remnants of ancient subducted Yangtze block. Seismic tomography reveals that the subducted Yangtze ancient block was broken off. In this paper we present tomographic images of the lithospheric velocity structure in details under the Debie-Sulu orogenic belt that such structures may be useful in. associating geodynamic to surface--tectonic processes and is important in study of ancient orogenic belt.
引文
[1]王清晨,孙枢,李继亮等.秦岭的大地构造演化.地质科学,1989,(2):129—142.WANG Qing-Chen, SUN Shu, LI Ji-Liang, et al. Tectonic evolution of the Qinling mountains. ScientiaGeologica Sinica (in Chinese), 1989, (2): 129--142.
[ 2 ] Okay A I, Sengoer A M C, Satn M. Tectonics of an ultrahigh-pressure metamorphic terrane: the DabieShan / Tongbai Shan orogen, China. Tectonics, 1993, 12(6): 1320-1334.
[ 3 ] Wang Xiaomin, Liu J G, Mao H K Coesite--bearing eclogite from Dabie Mountains in central ChinsGeology, 1989, 17:1085--1088.
[ 4 ] Xu Shutong, Okay A I, Ji Shouyuan, et al. Diamonds from bole Shan metamorphic rocks and itsimplication for tectonic setting. Science, 1992, 256:80--82.
[ 5 ] Cong B, Zhai M Carswell D A, et al. Petrogenesis of the ultrahigh--pressure rocks and their country rocksat Shuanghe in Dabieshan, central China. European J. Mineralogy, 1995, 7: 119--138.
[ 6 ] Ye kai, Hirajima T, Ishiwatari A, et al. The discovery of intergranular coesite in eclogite of Yangkou,Qingdao and its significance. Chinese Science Bulletin, 1996, 41(15):1407--1408.
[7]刘建华,刘福田,孙若昧等.秦岭-大别造山带及其南北缘地震层析成像.地球物理学报, 1995, 38(1):46-54.LIU Jian-Hua. LIU Fu-Tian, SUN Ruo-Mei, et al. Seismic tomography beneath the Qinling-Dabie orogenicbelts and both the northern and southern fringes. Chinese J Geophys (in Chinese), 1995. 38(l):46--54.
[8]董树文,吴宣志,高锐等.大别造山带地壳速度结构与动力学.地球物理学报,1998,41(3):349—361.DONG Shu-Wen, WU Xuan-Zhi, Gao Rui, et al. On the crust velocity levels and dynamics of theDabieshan orogenic belt Chinese J Geophys. (in Chinese), 1998, 41(3):349--361.
[9]王椿镛,张先康,陈步云等.大别造山带的地壳结构研究.中国科学(D辑),1997,27(3):221—226.WANG Chun-yong, ZHANG Xian-Kang, CHENG Bu-Yun et al. The study on the crustal structure ofDabie orogenic belt. Science in China (Series D)(in Chinese), 1997, 27(3):221--226.
[10]董树文,孙先如,张勇等.大别山碰撞造山带基本结构.科学通报,1993,38(6):542—545.DONG Shu-Wen, SUN Xian-Ru, ZHANG Yong, et al. The basic tectonics of Dabieshan collisional orogen.Chinese Science Bulletin (in Chinese), 1993, 38(6):542--545.
[11] Cong B, Wang Q, Zhai M et al., UHP metamorphic rocks in the Dabie-Su-Lu region, China: Theirformation and exhumation. Island Arc, 1994, 3: 135--150.
[12] Wang Q, Cong B. Tectonic implication of UHP rocks from the Dabie Mountains. Science in China (SeriesD), 39(3): 311-318.
[13]刘福田,李强,胡小幸.走时反演及其应用.地球物理学报,1982,25(6):696-710.LIU Fu-Tian LI Qiang, HU Xiao-Xing. Travel times inversion and its application. Chinese J. Geophys. (inChinese), 1982, 25(6):696--710.
[14]刘福田.震源位置和速度结构的联合反演(I)──理论和方法.地球物理学报,1984,27(2):167—175.LIU Fu-Tian, Simultaneous inversion of earthquake hypocenters and velocity structure (I)--Theory andmethod. Chinese J Geophys. (in Chinese), 1984, 27(2):167--175.
[15]刘福田,李强,吴华等.用于速度图像重建的层析成像法.地球物理学报,1989,32(1):46—61.LIU Fu-Tian, LI Qiang, WU Hua, et al. On the tomographic inverse method used in velocity image reconstruction. Chinese J Geophys. (in Chinese), 1989, 32(l):46--61.
[16]袁学诚.秦岭岩石圈速度结构与蘑菇云构造模型.中国科学(D辑),1996,26(3):209—215.YUAN Xue-Cheng. The velocity structures of the Qinling lithosphere and its mushroom tectonic model.Science in China (Series D)(in Chinese), 1996, 26(3):209--215..
[17] YANG Wen-Cai. Crustal structure and development of Sulu UHPM terrane in east-central China Episodes,1997, 20(2): 100-103.
[18] Kennett B L N, Engdahl E R.Travel times for global earthquake location and Phase identification. Gephys.J. Int., 1991, 105(3):429-465.
[19]龙汉春.试论华北地区地壳拉张,挤压与裂谷推覆构造的成因联系.地质评论,1988,34(2):105—113.LON Han-Chun. Relation of crustal extension and compression to rift and nappe structures in north China.Geological Review, 1988, 34(2): 105--l 13.
[20] Dewey J E Extensional collapse of orogens. Tectonics, 1988, 7(5): 1123--1140.
[21] You Zhendong, Suo Shutian, Zhong Zenqiu, et al. The extensional tectonics and retrometamorphicprocesses subsequent to the high-pressure and ultralhigh-pressure metamorphic events in Dabieshan, China.Continental Dynamics, 1998, 3(1-2): 63-71.
[22]从柏林,王清晨,张海政等.中国合肥盆地新生代火山岩成因岩石学研究.岩石学报,1996,12(3):370—381.CONG Bo-Lin, WANG Qing-Chen, ZHANG Hai-Zheng, et al. Petrogenesis of cenozoic volcanic rocks inHefei basin, China. Acata Petrologica Sinica (in Chinese). 1996. 12(3).370--381
[23]高山,金振民,Kern H等.大别超高压榴辉岩高温高压下地震波速度和密度的初步实验研究──对造山带地壳深部组成和莫霍面性质的启示.科学通报.1997.42(8)、862-866GAO Shan, JIN Zhen-Min, Kern H, et al. Preliminary experimental study of seismic velocity and density athigh temperature and high pressure on ultralhigh-pressure eclogite from Debie-- Implications to thecomposition of the crustal and the Moho's characteristics in orogen. Chinese Science Bulletin (in Chinese),1997, 42(8):862-866.
[24] Wang Qngchen, Cong Bolin, Zhu Rixiang. Geodynamics of UHP-rock-bearing continental collision zonein central China. In: Mantle dynamics and plate interactions in east Asia Geodynamics series 27, FlowerM F J, et al. ed. Washington D C: AGU Press, 1998, 259--267.
[25]徐佩芬,孙若昧,刘福田等.扬子板块俯冲、断离的地震层析成像证据.科学通报,1999,44(15):1658—1661XU Pei-Fen, SLJN Ru-Mei, LIU Fu-Tian, et al. Seismic tomography showing subduction and slab breakoffof the Yangtae block beneath the Dabie--Sulu orogenic belt. Chinese Science Bulletin (in Chinese), 1999,44(15): 1658~1661.
[26] Van der Voo K Spakman W, Bijwaard H Mesozoic subducted slabs under Siberia. Nature, 1999, 397:246--249.
[27] Van der Voo R. Spakman W, Bijwaard H. Tethyan suboucted slabs under india. Earth & Planet.Sci. Lei.,1999, 171: 7-20.
[28] Widiyantoro S, Van der Hilst R Structure and evolution of lithospheric slab beneath the Sunda Ace,Indonesia. Science, 1996, 271: 1566-1570.
[29]张旗,马宝林,刘若新等.一个消减带之上的大陆岩石圈地幔残片──安徽饶拔寨超镁铁岩的地球化学特征.中国科学(B辑),1995,25(8);867-873.ZHANG Q, Mao B, Liu R et al. A relic slice of continental lithospheric mantle. Science in China (SeriesB)(in Chinese), 1995, 25(8): 867--873.
[30] Yang J, Godard G, Kienast J R, et al. Ultrahigh-pressure (60 kbar) magnesite-beating garnet peridotitesfrom northeastern Jiangsu, China. J Geol, 1993, 101:541--554.
[31] Davies J H, Von Blanckenburg E Slab breakoff: a model of lithosphere detachment and its test in themagmatism and deformation of collisional orogens. Earth & Planet. Sci. Let., 1995, 129:85--102.
[32] Zhang R Y, Lion J G. Ultrahigh-pressure metamorphism of the Sulu terrane, eastrn China: a prospectiveview. Continental Dynamics, 1998, 3(1-2):32-53.
[33]从柏林,王清晨.大别山-苏鲁超高压变质带研究的最新进展.科学通报,1999,44(11):1127—1141.CONG Bo-Lin, WANG Qing-Chen. The newest progress of research on ultrahigh-pressure metamorphic rocksin the Dabie-Sulu orogenic belt. Chinese Science Bulletin (in Chinese), 1999, 44(11): 1 127--l 141.
[ 2 ] Okay A I, Sengoer A M C, Satn M. Tectonics of an ultrahigh-pressure metamorphic terrane: the DabieShan / Tongbai Shan orogen, China. Tectonics, 1993, 12(6): 1320-1334.
[ 3 ] Wang Xiaomin, Liu J G, Mao H K Coesite--bearing eclogite from Dabie Mountains in central ChinsGeology, 1989, 17:1085--1088.
[ 4 ] Xu Shutong, Okay A I, Ji Shouyuan, et al. Diamonds from bole Shan metamorphic rocks and itsimplication for tectonic setting. Science, 1992, 256:80--82.
[ 5 ] Cong B, Zhai M Carswell D A, et al. Petrogenesis of the ultrahigh--pressure rocks and their country rocksat Shuanghe in Dabieshan, central China. European J. Mineralogy, 1995, 7: 119--138.
[ 6 ] Ye kai, Hirajima T, Ishiwatari A, et al. The discovery of intergranular coesite in eclogite of Yangkou,Qingdao and its significance. Chinese Science Bulletin, 1996, 41(15):1407--1408.
[7]刘建华,刘福田,孙若昧等.秦岭-大别造山带及其南北缘地震层析成像.地球物理学报, 1995, 38(1):46-54.LIU Jian-Hua. LIU Fu-Tian, SUN Ruo-Mei, et al. Seismic tomography beneath the Qinling-Dabie orogenicbelts and both the northern and southern fringes. Chinese J Geophys (in Chinese), 1995. 38(l):46--54.
[8]董树文,吴宣志,高锐等.大别造山带地壳速度结构与动力学.地球物理学报,1998,41(3):349—361.DONG Shu-Wen, WU Xuan-Zhi, Gao Rui, et al. On the crust velocity levels and dynamics of theDabieshan orogenic belt Chinese J Geophys. (in Chinese), 1998, 41(3):349--361.
[9]王椿镛,张先康,陈步云等.大别造山带的地壳结构研究.中国科学(D辑),1997,27(3):221—226.WANG Chun-yong, ZHANG Xian-Kang, CHENG Bu-Yun et al. The study on the crustal structure ofDabie orogenic belt. Science in China (Series D)(in Chinese), 1997, 27(3):221--226.
[10]董树文,孙先如,张勇等.大别山碰撞造山带基本结构.科学通报,1993,38(6):542—545.DONG Shu-Wen, SUN Xian-Ru, ZHANG Yong, et al. The basic tectonics of Dabieshan collisional orogen.Chinese Science Bulletin (in Chinese), 1993, 38(6):542--545.
[11] Cong B, Wang Q, Zhai M et al., UHP metamorphic rocks in the Dabie-Su-Lu region, China: Theirformation and exhumation. Island Arc, 1994, 3: 135--150.
[12] Wang Q, Cong B. Tectonic implication of UHP rocks from the Dabie Mountains. Science in China (SeriesD), 39(3): 311-318.
[13]刘福田,李强,胡小幸.走时反演及其应用.地球物理学报,1982,25(6):696-710.LIU Fu-Tian LI Qiang, HU Xiao-Xing. Travel times inversion and its application. Chinese J. Geophys. (inChinese), 1982, 25(6):696--710.
[14]刘福田.震源位置和速度结构的联合反演(I)──理论和方法.地球物理学报,1984,27(2):167—175.LIU Fu-Tian, Simultaneous inversion of earthquake hypocenters and velocity structure (I)--Theory andmethod. Chinese J Geophys. (in Chinese), 1984, 27(2):167--175.
[15]刘福田,李强,吴华等.用于速度图像重建的层析成像法.地球物理学报,1989,32(1):46—61.LIU Fu-Tian, LI Qiang, WU Hua, et al. On the tomographic inverse method used in velocity image reconstruction. Chinese J Geophys. (in Chinese), 1989, 32(l):46--61.
[16]袁学诚.秦岭岩石圈速度结构与蘑菇云构造模型.中国科学(D辑),1996,26(3):209—215.YUAN Xue-Cheng. The velocity structures of the Qinling lithosphere and its mushroom tectonic model.Science in China (Series D)(in Chinese), 1996, 26(3):209--215..
[17] YANG Wen-Cai. Crustal structure and development of Sulu UHPM terrane in east-central China Episodes,1997, 20(2): 100-103.
[18] Kennett B L N, Engdahl E R.Travel times for global earthquake location and Phase identification. Gephys.J. Int., 1991, 105(3):429-465.
[19]龙汉春.试论华北地区地壳拉张,挤压与裂谷推覆构造的成因联系.地质评论,1988,34(2):105—113.LON Han-Chun. Relation of crustal extension and compression to rift and nappe structures in north China.Geological Review, 1988, 34(2): 105--l 13.
[20] Dewey J E Extensional collapse of orogens. Tectonics, 1988, 7(5): 1123--1140.
[21] You Zhendong, Suo Shutian, Zhong Zenqiu, et al. The extensional tectonics and retrometamorphicprocesses subsequent to the high-pressure and ultralhigh-pressure metamorphic events in Dabieshan, China.Continental Dynamics, 1998, 3(1-2): 63-71.
[22]从柏林,王清晨,张海政等.中国合肥盆地新生代火山岩成因岩石学研究.岩石学报,1996,12(3):370—381.CONG Bo-Lin, WANG Qing-Chen, ZHANG Hai-Zheng, et al. Petrogenesis of cenozoic volcanic rocks inHefei basin, China. Acata Petrologica Sinica (in Chinese). 1996. 12(3).370--381
[23]高山,金振民,Kern H等.大别超高压榴辉岩高温高压下地震波速度和密度的初步实验研究──对造山带地壳深部组成和莫霍面性质的启示.科学通报.1997.42(8)、862-866GAO Shan, JIN Zhen-Min, Kern H, et al. Preliminary experimental study of seismic velocity and density athigh temperature and high pressure on ultralhigh-pressure eclogite from Debie-- Implications to thecomposition of the crustal and the Moho's characteristics in orogen. Chinese Science Bulletin (in Chinese),1997, 42(8):862-866.
[24] Wang Qngchen, Cong Bolin, Zhu Rixiang. Geodynamics of UHP-rock-bearing continental collision zonein central China. In: Mantle dynamics and plate interactions in east Asia Geodynamics series 27, FlowerM F J, et al. ed. Washington D C: AGU Press, 1998, 259--267.
[25]徐佩芬,孙若昧,刘福田等.扬子板块俯冲、断离的地震层析成像证据.科学通报,1999,44(15):1658—1661XU Pei-Fen, SLJN Ru-Mei, LIU Fu-Tian, et al. Seismic tomography showing subduction and slab breakoffof the Yangtae block beneath the Dabie--Sulu orogenic belt. Chinese Science Bulletin (in Chinese), 1999,44(15): 1658~1661.
[26] Van der Voo K Spakman W, Bijwaard H Mesozoic subducted slabs under Siberia. Nature, 1999, 397:246--249.
[27] Van der Voo R. Spakman W, Bijwaard H. Tethyan suboucted slabs under india. Earth & Planet.Sci. Lei.,1999, 171: 7-20.
[28] Widiyantoro S, Van der Hilst R Structure and evolution of lithospheric slab beneath the Sunda Ace,Indonesia. Science, 1996, 271: 1566-1570.
[29]张旗,马宝林,刘若新等.一个消减带之上的大陆岩石圈地幔残片──安徽饶拔寨超镁铁岩的地球化学特征.中国科学(B辑),1995,25(8);867-873.ZHANG Q, Mao B, Liu R et al. A relic slice of continental lithospheric mantle. Science in China (SeriesB)(in Chinese), 1995, 25(8): 867--873.
[30] Yang J, Godard G, Kienast J R, et al. Ultrahigh-pressure (60 kbar) magnesite-beating garnet peridotitesfrom northeastern Jiangsu, China. J Geol, 1993, 101:541--554.
[31] Davies J H, Von Blanckenburg E Slab breakoff: a model of lithosphere detachment and its test in themagmatism and deformation of collisional orogens. Earth & Planet. Sci. Let., 1995, 129:85--102.
[32] Zhang R Y, Lion J G. Ultrahigh-pressure metamorphism of the Sulu terrane, eastrn China: a prospectiveview. Continental Dynamics, 1998, 3(1-2):32-53.
[33]从柏林,王清晨.大别山-苏鲁超高压变质带研究的最新进展.科学通报,1999,44(11):1127—1141.CONG Bo-Lin, WANG Qing-Chen. The newest progress of research on ultrahigh-pressure metamorphic rocksin the Dabie-Sulu orogenic belt. Chinese Science Bulletin (in Chinese), 1999, 44(11): 1 127--l 141.
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