中国大陆科学钻探主孔100~2000m岩石弹性波速度:对地震深反射的约束
Elastic wave velocities of the 2000m depth at Chinese Continental Scientific Drilling: Constraints on deep seismic reflection
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摘要: 在常温常压条件对中国大陆科学钻CCSD主孔岩心的700样品进行了弹性波速度测量,并建立了主孔2000m的波速(Vp和Vs)连续剖面,为检验地球物理模型的合理解释提供了岩石物理学方面的宝贵资料。主孔中新鲜榴辉岩纵波速度(Vp)最大(7.86km/s),正副片麻岩波速最小,又分别为5.53km/s和5.71km/s,榴辉岩的波速随着退变质作用的增强而明显减小。主孔2000m总平均Vp速度为6.2km/s,它与地球物理探测方法获得的大别-苏鲁造山带上地壳具有6.2-6.3km/s高速层结论是一致的。大部分岩石具有明显地震波各向异性。水饱和度使岩石纵波(Vp)速度和剪切波速度(Vs)分别增加19%和6%,而使Vp的各向异性降低3%~4%。不同岩性界面的反射系数(Rc)是产生地震反射的主要原因。金红石榴辉岩与片麻岩之间具有很高的反射系数(0.24-0.31)。韧性剪切带中糜棱岩化片麻岩和面理化榴辉岩使岩石各向异性和反射强度明显增加。岩石微裂隙与主孔原位波速变化有密切关系。饱水岩石速度(Vp和Vs)可以代表CCSD主孔原位状态的地震波速度。上述成果为本区地震反射体成因提供了重要的岩石物理性质约束。Abstract: The elastic wave velocities of 700 samples from main hole of Chinese Continental Scientific Drilling ( CCSD) have been performed in the conditions of room temperature and pressure. The continuous section of seismic velocities ( VP and Vs ) from 100m to 2000m was constructed, which provides an important petrophysical data for interpretation of geophysical model. Fresh eclogite yields the biggest compressional wave velocity (7. 86km/s) , and gneiss has smaller velocity (5. 53 -5. 71km/s) . Seismic velocity of eclogite significantly decreases with increase of retrogressive metamorphism. Overall average Vp velocity of main hole of 2000m rook is 6. 2km/s which is correspondent to conclusion with high velocity zone (6. 2-6. 3km/s) of the upper crust in Dabie-Sulu orogenic belt inferred from geophysical methods. Most rocks at the mail hole have pronounced seismic anisotropy. The velocity of Vp and Vs with water-saturated rock increases by a factor of 19% and 10% , respectively. Conversely, anisotropy of VP and Vs with water-saturated rock reduces 3% - 4%. Reflective coefficient (Rc ) of different lithological boundaries is main factor producing seismic reflection. The lithological boundary between rutile-bearing eclogite and gneiss has the biggest reflective coefficient (0. 24 - 0. 31). Anisotropy and reflective strength is enhanced by mylonitic gneiss and foliated eclogite in ductile shear zone. Anisotropy and shear wave splitting of gneiss and eclogite are caused by the foliation of rocks, as confirmed by laboratory measurements under simulated in situ condition at high pressure and high temperature. Micro-cracks of rocks is closely related to in situ velocity variation. Velocities ( VP and Vs ) water-saturated rocks may represent in situ seismic velocity at main hole of the CCSD. The measurements of elastic wave velocities give an important constraints on the genesis of seismic reflector for this area.
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Key words:
- Ultrahigh-pressure rock /
- Elastic wave velocity /
- Anisotropy /
- Seismic reflector /
- CCSD /
- Donghai
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[1] [1]Babuska Y, Fiala J, Mayson DJ, Lieberman R C. 1978. Elastic properties of eclogite rocks from the Bohemian massif. Studia Geophysica et Geodetic, 22: 348 - 361
[2] [2]Berckheemer A. Rauen A, Winter H, Kern H. 1997. Petrophysical properties of the 9 -km deep crustal section at KTB. J. Geophys.Res., 102(B8): 18337-18362
[3] [3]Biot M A. 1956. Theory of propagation of elastic waves in a fluid saturated porous solid 1. low frequency range. J. Acoustic. Soc.Am. , 28(2): 168 -178
[4] [4]Brich F. 1961. The velocity of compressional waves in rocks to 10 kbars.J. Geophys. Res. , 66:2199-2224
[5] [5]Chen Y, Jin ZM, Ou XG, Jin SY and Xu HJ. 2004. Deformation features of gneiss and UHP eclogite from ductile shear zone and its relation with seismic velocity anisotropy: Evidences from core samples at depth of 680 ~ 1200m of CCSD. Acta Petrologica Sinica,20( 1 ) :97 -108 (in Chinese with English abstract)
[6] [6]Christensen N L. 1989. Reflectivity and seismic properties of the deep continental cmst. J. Geophys. Res., 94:17795-17804
[7] [7]Chunyong Wang, Rongsheng zeng, Mooney W D, Hacker B R. 2000. A crustal model of the ultrahigh-pressure Dabie shan orogenic belt,China, derived from deep seismic refraction profiling. J. Geophys,Res. , 105 (B5): 10857 - 10869
[8] [8]Dong Shuwen, Wu Xuanzhi, Gao Rui. 1998. On the crust velocity levels and dynamics of the Dabie shan orogenic belt. Chinese J.Geophys. , 41 (3): 349 -361 (in Chinese with English abstract)
[9] [9]Emmeimman R, Lauterjung L. 1997. The German continental deep drilling program KTB: Overview and major results. J. Geophys.Res., 102(B8): 18179-18201
[10] [10]Fountain D M, Boundy T M, Austrheim H. 1994. Eclogite facies Shear zone - deep crustal reflector? Tectonophysics, 232: 411 - 424
[11] [11]Fountain D M, Hurich C A. Smithson S B. 1984. Seismic reflectivity of mylonite zone in the crust. Geology, 12:195 -198
[12] [12]Gao Sha, Jin Zheming, Jin Shuyan, Xu Ziqin, Dong Shuwen. 1997. Preliminary study on seismic velocities and density of ultrahighpressure eclogite from Dabie shan: Implication for composition of deep crust and Moho characsters. Chinese Science Bulletin, 42 (8):862 - 866 ( in Chinese)
[13] [13]Gao Shan, Liu Yongsheng. 1999. Deep structures and composition of continental crust. In: Zheng Y-F ed. Chenical Geodynamics.Beijing: Science Press, 168 - 201 (in Chinese)
[14] [14]Holl A, Althaus E, Lempp C. 1997. The petrophysical behavior of crustal rocks under the influence of fluids. Tectonophysics, 275:253 - 260
[15] [15]Huenges E, Erizinger J, Kuck J. 1997. The permeable crust:Geohydraulic properties down to 9101 m depth. J. Geophys. Res. ,102(B8): 18255 - 18266
[16] [16]Jin Zhenmin, Green W H, Zhou Yi. 1994. Melt topology in partially molten peridotite during ductile deformation. Nature, 372:164 -167
[17] [17]Jin Shuyan, Jiao Shuqiang. 1998. Fabric measurements of omphacite from ultrahigh-pressure eclogite and rheological significances. Earth Science, 23( 1 ): 37 -40 (in Chinese with English abstract)
[18] [18]Jin shuyan. 1997. Seismic anisotropy of continental lithosphere and its dynamical significances. In: Zhan Bingxi ( ed. ). Modem methods for the lithospheric study. Beijing: Publishing House of Atomic Energy, 79 - 88 ( in Chinese)
[19] [19]Jin Zhenmin, Yu Ridong, Yang Wencai and Ou Xingong. 2003. Mantle -derived xenoliths of peridotite from Pingmingshan, Donghai County, Jiangsu province and their implications for deep structures.Acta Geologica Sinica, 77 (4) :451 -462 (in Chinese with English abstract)
[20] [20]Jones K A, Warner M R, Morgan R P. 1996. Coincident nomalincidence and wide-angle reflection from the Moho: evidence for crustal seismic anisotropy. Tectonophysics, 264 ( 1-4 ): 205 - 217
[21] [21]Jones T, Hur A. 1982. Seismic velocity and anisotropy in mylonites and reflectivity of deep crust fault zones. Geology, 10 : 260 - 263
[22] [22]Kern H, Shao Gao, Zhenmin Jin, Popp T, Shuyan Jin. 1999. Petrophysical studies on rocks from the Dabie ultrahigh-pressure (UHP) metamorphic belt, Central China: implications for the composition and delamination of the lower crust. Tectonophysics,301:191 -215
[23] [23]Kern H, Wenk H B. 1990. Fabric-related velocity anisotropy and shearwave splitting in rocks from the Santo Rosa mylonite zone,California. J. Geophys. Res., 95: 11213- 11223金振民等:中国大陆科学钻探主孔100~2000m岩石弹性波速度:对地震深反射的约束
[24] [24]Kern H, Zhenmin Jin, Shao Gao, Popp T, Zhiqin Xu. 2002. Physical properties of ultrahigh-pressure metamorphic rocks from Sulu terrain,eastern China: implications for the seismis structune of the Donghai (CCSD) drilling site. Tectonophysics, 354: 315 - 330
[25] [25]Knigh R, Nolen-Hoeksema R. 1990. A laboratory study of the dependence elastic wave velocities on pore scale fluid distribution.Geophys. Res. Lett. , 17(10): 1529- 1532
[26] [26]Kozlovsky Y A. 1987. The super-deep well of the kola peninsula. Berlin:Springer
[27] [27]Kumazawa M, Helmstaedt H, Masaki K. 1971. Elastic properties of eclogite xenoliths from Diatremes of the East Colorado plateau and their implication to the upper mantle structure. J. Geophys. Res. ,76(5): 1231 - 1247
[28] [28]Liu Fulai, Zhang Zhemin, Xu Zhiqin. 2003. Three-dimensional distribution of ultrahigh-pressure minerals in Sulu terrane. Acta Geologica Sinica, 77 ( 1 ): 69 - 84 ( in Chinese with English abstract )
[29] [29]Liu Futian, Xu peifen, Liu Jinsong. 2003. The crustal velocity structure of the continental deep subduction belt: study on the Eastern Dabie orogen by seismic wide-angle reflection/refraction. Chinese J.Geophys. , 46 (3): 366 -372 (in Chinese with English abstract)
[30] [30]Maghgnani M H. Ramananagtoandro R, Clark S P. 1974. Compressional and shear wave velocities in granulife facies rocks and eclogites to 10 Kbar. J. Geophys. Res., 79(35):5427-5446
[31] [31]Mauler A, Burlini L, Kunze K, Philippot P. 2000. P-wave anisotropy in eclogite and relationship to the omphacite crystallographic fabric.Phys. Chem. Earth (A), 25(2): 119-126
[32] [32]Mooney W D, Meissner R. Multi-genetic regime of crustal reflectivity: a review of seismic reflection profiling, In: Fountain D M ( ed. ).Continental Lower crust. Berling. Springer, 45 -79
[33] [33]Murase T, Kushiro I. 1979. Compressional wave velocity in partially molten peridotite at high pressures. Carnegie Inst. Washington.Yearb. , 78:559-562
[34] [34]Murase T, Fakuyama H. 1980. Shear wave velocity in partially molten peridotite at high pressures. Carnegie Inst. Washington. Yearb. ,79:307-310
[35] [35]Passchier C W. 1986. Mylonite in the continental crust and their role as seismic reflectors. Geologie en Mijnbouw, 65:167 -176
[36] [36]Pavlenkoba NI. 1992. The kola superdeep drilling and the nature of seismic boundaries. Terra Nova, 4:117 - 123
[37] [37]Rao, M V M S, Ramana Y V, Gogte B S. 1974. Dependence of compressional velocity on the mineral chemistry of eclogite. Earth Planet. Sci. Lett. , 23:15 -20
[38] [38]Shaocheng Ji, Salisbury H. 1993. Shear-wave velocities, anisotropy and splitting in high-grade mylonites. Tectonophysics, 221: 453 -473
[39] [39]Shi Ge, Shen Wenlue, Yang Dongquan. 2003. The relationship of elastic wave velocity with saturation and fluid distribution in pore space.Chinese J. Geophys. , 46( 1 ): 138 - 142 ( in Chinese with English abstract )
[40] [40]Shi Xingjue, Xu Guoming. 1995. Experimental study on the effect of water-saturation on compressioual and shear wave velocity and attenuation. Chinese J. Geophys. , 38 (supplement): 281 - 287( in Chinese with English abstract)
[41] [41]Siegesmund S, Kern H, Vollbrecht A. 1991. The effect of oriented microcracks on seismic velocities in an ultramylonite.Tectonophysics, 186: 241 -251
[42] [42]Siliver P G. 1996. Seismic anisotropy beneath the continemts: Probing the depth of Geology. Annual Rew. Earth Planet. Sci. , 24: 358 -432
[43] [43]Warner M. 1990. Absolute reflection coefficients from deep seismic reflections. Tectonophysics, 173:15-23
[44] [44]Wenjin Zhao. 1993. Deep seismic reflection evidences for continental underthrusting beneath southern Tibet. Hature, 366: 557 - 559
[45] [45]Wu Xuanzhi. 1997. Near vertical reflection method and its substance of deep reflection. In: Zhang Bingxi ( ed. ). Modern methods for the lithospheric study. Beijing: Publishing House of Atomic Energy, 37-46 (in Chinese)
[46] [46]Xu Shutong, Liu Yican, Chen Guanbao, Lompagnoni F, Rofo E, He Mouchun, Liu Huifang. 2003. New discovery of diamonds of eclogite from Sulu area. Chinese Science Bulletin, 48(10): 1069 -1075 (in Chinese)
[47] [47]Xu Zhiqin, Yang Wencai, Zhang Zeming. 1998. Scientific significance and site-selection of the first Chinese Continental Scientific Deep Drillhole. Continental Dynamics, 3: 1 - 3
[48] [48]Yang Wencai, Cheng Zhenyan, Chen Guojiu. 1999. Geophysical investigations of northern Sulu UHPM belt (Ⅰ): Deep seismic reflection. Chinese J. Geophys. , 42( 1 ): 41 -52 (in Chinese with English abstract)
[49] [49]Yang Wencai, Zhang Chuhe, Zhu Guangmin. 2002. Calibration of seismic reflectors in Chinese Continental Drilling area. Chinese J.Geophys., 45 ( 3 ): 370 - 384 ( in Chinese with English abstract)
[50] [50]Yang Xiaosong, Jin Zhenmin. 1998. The Significance of the studies on petrophysical property measurements in continental scientific drilling. Earth Science Frontiers, 5 ( 4 ): 338 - 346 ( in Chinese with English abstract)
[51] [51]Yu Qingfan, Yao Changli, Meng Xiaohong. 2002. Petrophysical properties at site of continental scientific Drilling, Northern Jianshu province. Chinese J. Geophys. , 45 ( 1 ): 93 - 100 ( in Chinese with English abstract)
[52] [52]Yuan Xuecheng, Klemperer S, Teng Wenbang, Liu Laixiang, Chetwin E. 2003. Crustal structure and exhumation of the Dabie shan ultrahigh-pressure orogen, eastern China, from seismic reflection profiling. Geology, 31 ( 5 ): 435 - 438
[53] [53]Zhang Z M, You Z D, Han Y J, Song L K. 1995. Petrology metamorphic process and genesis of the Dabie-Sulu eclogite belt, east-central China. Acta Geologica Sinica, 69 (4): 306 - 325
[54] [54]Zhao Zhidan, Xie Hongsheng, Zhou Wenge. 2001. Density and seismic velocity of eclogite from Dable shan and implications for cycle of crust-mantle. Bulletin of Mineralogy, Petrology and Geochemistry,20( 1 ): 52 -57 (in Chinese with English abstract)
[55] [55]陈意,金振民,欧新功,金淑燕,徐海军.2004.韧性剪切带中片麻岩和超高压榴辉岩变形特征及其与地震波速各向异性的关系:来自中国大陆科学钻探(CCSD)680~1200米岩心的证据.岩石学报,20(1):97-108
[56] [56]董树文,吴宣志,高锐.1998.大别造山带地壳速度结构与动力学.地球物理学报,41(3):349-361
[57] [57]高山,金振民,Kern H,金淑燕,许志琴,董树文,杨天楠.1997.大别山超高压榴辉岩高温高压下地震波速和密度的初步研究--对造山带地壳深部组成和莫霍性质的启示.科学通报,42(8):862-806
[58] [58]高山,刘勇胜.1999.大陆地壳深部结构与组成.见:郑永红主编.化学地球动力学.北京:科学出版社,168-201
[59] 金淑燕,焦述强.1998.超高压榴辉岩中绿辉岩组构测定及其流变学意义.地球科学,23(1):37-40
[60] [60]金淑燕.1997.大陆岩石圈各向异性和动力学意义.见:张炳熹,洪大卫,吴宣志主编.岩石圈研究的现代方法.北京:原子能出版社,79-32
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