514 profile across Songpan block-west Qinling orogenic belt has revealed the details of lithosphere deformation. The superimposition of the thrust dup

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1 Sep : Acta Geoscientica Sinica Vol.32 No.5: www. 地球学报.com 深地震反射剖面再处理提供的证据 1, 2), 1, 2), 3), 4), 3), 1, 2), 5) 1, 2), 1), ; 2), ; 3) ( ), ; 4), ; 5), 摘要 : Ma,, -,,,, 35 km 关键词 : ; ; 中图分类号 : P542.5; P 文献标志码 : A doi: /cagsb Lithospheric Deformation Shortening of the Northeastern Tibetan Plateau: Evidence from Reprocessing of Deep Seismic Reflection Data GAO Rui 1, 2), WANG Hai-yan 1, 2), WANG Cheng-shan 3), YIN An 4), ZHANG Yu-xiu 3), LI Qiu-sheng 1, 2), GUO Tong-lou 5) 1, 2), LI Wen-hui 1) Lithosphere Research Center, Institute of Geology, Chinese Academy of Geological sciences, Beijing ; 2) Key Laboratory of Earthprobe and Geodynamics, Chinese Academy of Geological Sciences, Beijing ; 3) National Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing ; 4) Department of Earth and Space and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA ; 5) Southern China Exploration Division, Sinopec Company, Chengdu, Sichuan Abstract: Although most researchers both in China and abroad have agreed that the Tibetan plateau is the largest highland induced by the India-Asia collision over the past 60~50 Ma, its formation mechanism has long been a problem of controversy. Deep seismic reflection profiling is an effective technique for revealing the fine structure of the lithosphere and detecting the deformation style of the crust. The reprocessing of the deep seismic reflection ( : ) ( : 2006DFA21340) ( : ) ( : SinoProbe-02) 2010 : ; : : :,, 1950, : , 26 : gaorui@cags.net.cn

2 514 profile across Songpan block-west Qinling orogenic belt has revealed the details of lithosphere deformation. The superimposition of the thrust duplex structure in the upper crust and a sub-horizontal detachment in the middle crust and the vertical stacking of Moho at the bottom of the crust show that the lithospheric shortening deformation on the northeastern margin of the Tibetan Plateau was the main formation mechanism. The Kunlun fault 1000 km in length, one of the largest continental-scale strike-slip faults in Tibet, terminates at a sub-horizontal decollement with the depth of 35 km in the lowermost crust of Tibet. The study establishing the vertical structure of the lithosphere shows tectonic relationship between the western Qinling orogenic belt and the Zoige basin on the lithosphere scale. Key words: northeastern Tibetan Plateau; deep seismic reflection profile; lithospheric deformation shortening Ma, : (1), (England et al., 1982; Flesch et al., 2005); (2) ( ) (Zhao et al., 1987; Clark et al., 2000; Bird, 1991; Royden et al., 1997) : SKS GPS, (Hirn et al., 1984; Wittlinger et al., 1998); (Nelson et al., 1996; Royden et al., 2008), ( ) (Yin et al., 2000),,,,, 2004,, 260 km(, 2006a;, 2007), ,, 140 km 2004,,, (Burchfiel et al., 1989) 1 地质背景 1000 km, 8 15 Ma, 5 16 mm/yr, km (Kidd et al., 1988; Van et al., 2002; Fu et al., 2007; Kirby et al., 2007; Harkins et al., 2008) 1,,, (Jolivet et al., 2003; Chen et al., 1994) :, (Burchfiel et al., 1989; Kirby et al., 2007; Jolivet et al., 2003; Chen et al., 1994; Tapponnier et al., 2001) - - -, Ma (Fang et al., 2003; Horton et al., 2004) - ( ), -

3 : 515 图 1 深地震反射剖面位置图和简要构造背景 Fig. 1 Location of the deep seismic reflection profile and simplified tectonic setting of Tibet ; AB- ; AKM- - - ; OLS- This paper focuses on the study area in the virtual box; AB-location of the deep seismic reflection profile; AKM-Triassic Animaqing-Kunlun-Muztag sutures; OLS-early Paleozoic Qilian suture (<2 5 km), (, 2004) 2 深地震反射剖面数据采集和再处理, (, 2011;, 2011) ,,, 260 km,,, 100 m 400 m 5000 m SN , 50 m, 30 s, 120, ( 1) (, 2006a, b;, 2007; Wang et al., 2009) 2008,,, 140 km, 深地震反射剖面解释,, 2 4, 2, 表 1 深地震反射剖面数据采集参数 Table 1 Data collection parameters of the deep seismic reflection profiling /kg 16( ) 40( ) 200( ) 40( ) 840( ) 1000( ) /m 100( ) 400( ) 5000( ) 250( ) 1000( ) 30000( ) /m 20( ) 28( ) 50( ) 25( ) 35( ) 45( ) SN XL /s 30 30( ) 50( ) /m /ms 2 2 / 120( ) 30( ) 60

4 516 Fig. 2 图 2 重新处理的深地震反射时间剖面 ( 位置示意于图 1 虚方框中的 AB 线段 ) Reprocessed deep seismic reflection time section (location shown by AB segment in Fig. 1) (, 2004), ( 2 KL-S, KL-N KL), 30 35, 8 km, 65 70, 8 30 km 80,, ( 4) 35 km, ( 2 H-3, 3c) H-3, 40 km, 图 3 解释剖面局部举例 Fig. 3 Examples of the interpretation section a- ; b- ; c- ; d-moho, a-time profile images of data reprocessing; b-thrust structure in the south of the Kunlun fault; c-left-slip Kunlun fault extending downward and terminating at a sub-horizontal decollement; d-multiple Moho offset by thrusts, forming a thrust duplex system

: 517, IC-1 IC-2( 3a),, (0 20 km) ( 3a FD-1 FD-2) ( 3a F-1 3b) 10 km 30 50, ( 3), ( 3),,,, ( 3) : 30 40 km ( 4 UD, MD, LD, ), 6 9 km ( 3a M-1 M-5), 图 4 跨越昆仑左旋走滑断层的解释横剖面 ( 显示出岩石圈的变形样式 ; 位置示意如图 1 虚方框中的

5 : 517, IC-1 IC-2( 3a),, (0 20 km) ( 3a FD-1 FD-2) ( 3a F-1 3b) 10 km 30 50, ( 3), ( 3),,,, ( 3) : km ( 4 UD, MD, LD, ), 6 9 km ( 3a M-1 M-5), 图 4 跨越昆仑左旋走滑断层的解释横剖面 ( 显示出岩石圈的变形样式 ; 位置示意如图 1 虚方框中的 AB 线段 ; UD, MD, LD 表示上中下拆离断层, 解释见正文 ) Fig. 4 An interpreted structural section across the left-slip Kunlun Fault based on this study (It shows the deformation style of the lithosphere; location is indicated by AB segment in Fig. 1; UD, MD and LD represent upper, middle and lower detachment fault. For interpretation, see the text)

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8 520 Growth of the Tibet Plateau[J]. Science, 294(5547): VAN D W J, TAPPONNIER P, RYERSON F J, MERIAUX A S, MEYER B, GAUDEMER Y, FINKEL R C, CAFFEE M W, ZHAO G G, XU Z Q Uniform postglacial slip-rate along the central 600 km of the Kunlun Fault (Tibet), from Al-26, Be-10, and C-14 dating of riser offsets, and climatic origin of the regional morphology[j]. Geophys. J.Inter., 148(3): WANG H Y, GAO R, LI Q S, ZHANG J S, LU Z W, HOU H S Lithosphere structure of the west Qinling orogenic belt revealed by deep seismic reflection profile[j]. 2009AGU (American Geophysical Union)Fall Metting, San Francisco, CA, T11B WANG Hai-yan, GAO Rui, MA Yong-sheng, ZHU Xuan, LI Qiu-sheng, KUANG Chao-yang, LI Peng-wu, LU Zhan-wu Basin-range coupling and lithosphere structure between the Zoige and the west Qinling[J]. Chinese Journal of Geophysics, 50(2): (in Chinese with English abstract). WITTLINGER G, TAPPONNIER P, POUPINET G, JIANG M, SHI D, HERQUEL G, MASSON F Tomographic evidence for localized lithospheric shear along the Altyn Tagh fault[j]. Science, 282(5386): YIN A, DANG Y Q, ZHANG M, CHEN X H, MCRIVETTE M W Cenozoic tectonic evolution of the Qaidam basin and its surrounding regions (Part 3): structural geology, sedimentation, and regional tectonic reconstruction[j]. Geol. Soc. Am. Bull., 120(7-8): YIN A, HARRISON T M Geological evolution of the Himalayan-Tibetan Orogen.Annu[J]. Rev. Earth Planet. Sci., 28: ZHAO W, MORGAN W J Injection of Indian crust into Tibet lower crust: A two-dimensional finite element model study[j]. Tectonics, 6(4): 地球学报编辑部网站权威发布 OA 期刊网络版 3, OA(Open Access) , 1979, ,, PDF, 2008,,,,,, (ywf ywf0809 ywf0901) 本刊编辑部报道

14 17.,., Fig. 1 Bougeur gravity map of research region 2 Fig. 2 Magnetic map of research region

14 17.,., Fig. 1 Bougeur gravity map of research region 2 Fig. 2 Magnetic map of research region 1 7 1 Vol. 17 No. 1 2002 3 (13 23) PROGRESS IN GEOPHYSICS March 2002 (,,100101) [ ],, 39.,,. [ ] ; ; [] P738 [] A [ ]100422903 (2002) 0120013211 0,,.,,, NE [1 ],.., ( NE, EW,NE ),.,.,,. 1 20 20 km ( 10