LI HaiBing,
XU ZhiQin,
WANG Huan et al
.2018.Fault behavior, physical properties and seismic activity of the Wenchuan earthquake fault zone: evidences from the Wenchuan earthquake Fault Scientific Drilling project (WFSD).Chinese Journal Of Geophysics,61(5): 1680-1697,doi: 10.6038/cjg2018M0257
Fault behavior, physical properties and seismic activity of the Wenchuan earthquake fault zone: evidences from the Wenchuan earthquake Fault Scientific Drilling project (WFSD)
LI HaiBing1, XU ZhiQin1,2, WANG Huan1, ZHANG Lei1, HE XiangLi1, SI JiaLiang1, SUN ZhiMing3
1. Key Laboratory of Deep-Earth Dynamics of Natural Resources Ministry, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China; 2. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China; 3. Key Laboratory of Paleomagnetism and Tectonic Reconstruction of Natural Resources Ministry, Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China
Abstract：Fault zone composition, structures and physical properties are the keys to understand the fault deformation mechanisms and earthquake generation processes. Seismic and aseismic slip behaviors are essential to learn about fault zone seismicity and mountain uplift processes, which provide scientific basis for Earthquake prevention and disaster reduction. Based on surface outcrop investigation and detailed research on the drilling cores of the Wenchuan earthquake Fault Scientific Drilling (WFSD), fault zone characteristics, microstructures and physical properties of fault rocks were determined, and new knowledge about the fault zone deformation mechanisms and related Longmen Shan uplift are suggested: (1) The Yingxiu-Beichuan fault (YBF) dips to NW with an angle of 65° at shallow depth, consisting of ~180—280 m-wide fault rocks of cataclasite, pseudotachylyte (fossil earthquake), fault gouge and fault breccia. The fault zone has higher natural gamma and magnetic susceptibility, lower electrical resistivity and wave velocity, and a symmetrical fracture structure. Gouge graphitization and high magnetic susceptibility are observed in the fault zone due to the high temperature generated by ancient seismic faulting, indicating large earthquakes happened frequently along this fault. Large earthquakes (as Wenchuan earthquake) recurrence period is less than 6000—10000 years since late Cenozoic, charactered with millennium recurrence period. (2) The Guanxian-Anxian fault (GAF) dips to NW with an angle of 38°, consisting of ~40—50 m-thick fault breccia and fault gouge with lower magnetic susceptibility. Multi-scale structural analyzes show that the brittle fault rocks display characteristics of pressolution and ductile-like structures, indicating that the GAF is an aseismic fault with long-term creeping properties. Besides, phyllosilicates-rich gouge and pervasive micropores are responsible for weakening the GAF. The physical properties of the GAF are similar to that of the YBF, except the lower magnetic susceptibility. (3) Based on the empirical formula between fault displacement and fault core thickness, and taking the fault occurrences into consideration, a cumulative vertical displacement of >9 km is roughly estimated for the YBF, whereas that of the GAF is <3 km. Therefore, the accumulative vertical displacement generated by the long-term seismicity of the YBF is the main contribution to the Longmen Shan uplift.
Biegel R L, Sammis C G. 2004. Relating fault mechanics to fault zone structure. Advances in Geophysics, 47(6): 65-111. Bos B, Spiers C J. 2001. Experimental investigation into the microstructural and mechanical evolution of phyllosilicate-bearing fault rock under conditions favouring pressure solution. Journal of Structural Geology, 23(8): 1187-1202. Burchfiel B C, Royden L H, Van Der Hilst R D, et al. 2008. A geological and geophysical context for the Wenchuan earthquake of 12 May 2008, Sichuan, People's Republic of China. GSA Today, 18(7): 4-11. Chester F M, Evans J P, Biegel R L. 1993. Internal structure and weakening mechanisms of the San Andreas Fault. Journal of Geophysical Research, 98(B1): 771-786. Chester F M. 1995. A rheologic model for wet crust applied to strike-slip faults. Journal of Geophysical Research, 100(B7): 13033-13044. Chester F M, Chester J S. 1998. Ultracataclasite structure and friction processes of the Punchbowl fault, San Andreas system, California. Tectonophysics, 295(1-2): 199-221. Clark M K, Royden L H. 2000. Topographic ooze: Building the eastern margin of Tibet by lower crustal flow. Geology, 28(8): 703-706. Deng Q D, Chen S F, Zhao X L. 1994. Tectonics, seismisity and dynamics of Longmenshan Mountains and its adjacent regions. Seismology and Geology (in Chinese), 16(4): 389-403. Faulkner D R, Lewis A C, Rutter E H. 2003. On the internal structure and mechanics of large strike-slip fault zones: field observations of the Carboneras fault in southeastern Spain. Tectonophysics, 367(3-4): 235-251. Faulkner D R, Mitchell T M, Rutter E H, et al. 2008. On the structure and mechanical properties of large strike-slip faults. Geological Society, London, Special Publications, 299(1): 139-150. Fossen H. 2016. Structural Geology. 2nd ed. Cambridge: Cambridge University Press, 177-218. Fu B H, Shi P L, Guo H D, et al. 2011. Surface deformation related to the 2008 Wenchuan earthquake, and mountain building of the Longmen Shan, eastern Tibetan Plateau. Journal of Asian Earth Sciences, 40: 805-824. Fu B H, Shi P L, Zhang Z W. 2008. Spatial characteristics of the surface rupture produced by the MS8.0 Wenchuan Earthquake using high-resolution remote sensing imagery. Acta Geologica Sinica (in Chinese), 82(12): 1679-1687. Gan W J, Zhang P Z, Shen Z K, et al. 2007. Present-day crustal motion within the Tibetan Plateau inferred from GPS measurements. Journal of Geophysical Research: Solid Earth, 112(B8): B08416, doi: 10.1029/2005JB004120. Gratier J P, Irigm R G. 1986. Experimental pressure solution-deposition on quartz grains: the crucial effect of the nature of the fluid. Journal of Structural Geology, 8(8): 845-856. Gratier J P. 1987. Pressure solution-deposition creep and associated tectonic differentiation in sedimentary rocks. Geological Society, London, Special Publications, 29(1), 25-38, doi: 10.1144/GSL.SP.1987.029.01.03. Gratier J P, Richard J, Renard F, et al. 2011. Aseismic sliding of active faults by pressure solution creep: Evidence from the San Andreas Fault Observatory at Depth. Geology, 39(12): 1131-1134. Gratier J P, Thouvenot F, Jenatton L, et al. 2013. Geological control of the partitioning between seismic and aseismic sliding behaviours in active faults: Evidence from the Western Alps, France. Tectonophysics, 600: 226-242. He C G, Yao W M, Wang Z L, et al. 2006. Strength and stability of frictional sliding of gabbro gouge at elevated temperatures. Tectonophysics, 427(1-4): 217-229. He C G, Wang Z L, Yao W M. 2007. Frictional sliding of gabbro gouge under hydrothermal conditions. Tectonophysics, 445(3-4): 353-362. Huntington K W, Klepeis K A, with 65 Community Contributors. 2017. Challenges and opportunities for research in tectonics: Understanding deformation and the processes that link Earth systems, from geologic time to human time.//A Community Vision Document Submitted to the U. S. National Science Foundation. Janssen C, Wirth R, Wenk H R, et al. 2014. Faulting processes in active faults-evidences from TCDP and SAFOD drill core samples. Journal of Structural Geology, 65: 100-116. Kirby E, Reiners P W, Krol M A, et al. 2002. Late Cenozoic evolution of the eastern margin of the Tibetan Plateau: inferences from 40Ar/39Ar and (U-Th)/He thermochronology. Tectonics, 21(1): 1001, doi: 10.1029/2000TC001246. Kuo L W, Song S R, Huang L, et al. 2011. Temperature estimates of coseismic heating in clay-rich fault gouges, the Chelungpu fault zones, Taiwan. Tectonophysics, 502(3-4): 315-327. Kuo L W, Li H B, Smith S A F, et al. 2014. Gouge graphitization and dynamic fault weakening during the 2008 MW7.9 Wenchuan earthquake. Geology, 42(1): 47-50, doi: 10.1130/G34862.1. Kuo L W, Felice F D, Spagnuolo E, et al. 2017. Fault gouge graphitization as evidence of past seismic slip. Geology, 45(11), doi: 10.1130/G39295.1. Li H B, Fu X F, Van Der Word J, et al. 2008a. Co-seismic surface rupture and dextral-slip oblique thrusting of the MS8.0 Wenchuan earthquake. Acta Geologica Sinica (in Chinese), 82(12): 1623-1643. Li H B, Si J L, Pan J W, et al. 2008b. Deformation feature of active fault and recurrence intervals estimation of large earthquake. Geological Bulletin of China (in Chinese), 27(12): 19-42. Li H B, Wang H, Xu Z Q, et al. 2013. Characteristics of the fault-related rocks, fault zones and the principal slip zone in the Wenchuan Earthquake Fault Scientific Drilling Project Hole-1 (WFSD-1). Tectonophysics, 584: 23-42. Li H B, Xu Z Q, Niu Y X, et al. 2014. Structural and physical property characterization in the Wenchuan earthquake Fault Scientific Drilling project-hole 1 (WFSD-1). Tectonophysics, 619-620: 86-100. Li H B, Wang H, Yang G, et al. 2016. Lithological and structural characterization of the Longmen Shan fault belt from the 3rd hole of the Wenchuan Earthquake Fault Scientific Drilling project (WFSD-3). International Journal of Earth Sciences, 105(8): 2253-2272. Li Y, Zhou R J, Densmore A L, et al. 2006. Sedimentary responses to Late Cenozoic thrusting and strike-slipping of Longmen Shan along eastern margin of Tibetan Plateau. Acta Sedimentologica Sinica (in Chinese), 24(2): 153-164. Li Y, Zhou R J, Dong S L, et al. 2008. Surface rupture, thrusting and strike-slipping in the Wenchuan earthquake of Sichuan, China. Journal of Chengdu University of Technology (Science & Technology Edition) (in Chinese), 35(4): 404-413. Li Z W, Xu Y, Huang R Q, et al. 2011. Crustal P- wave velocity structure of the Longmenshan region and its tectonic implications for the 2008 Wenchuan earthquake. Science China Earth Sciences, 54(9): 1386-1393, doi: 10.1007/s11430-011-4177-2. Liu D L, Li H B, Lee T Q, et al. 2014. Primary rock magnetism for the Wenchuan earthquake fault zone at Jiulong outcrop, Sichuan Province, China. Tectonophysics, 619-620: 58-69. Liu J, Zhang Z H, Wen L, et al. 2008. The MS8.0 Wenchuan earthquake co-seismic rupture and its tectonic implications-an out-of-sequence thrusting event with slip partitioned on multiple faults. Acta Geologica Sinica (in Chinese), 82(12): 1707-1722. Logan J M, Friedman M, Higgs N, et al. 1979. Experimental studies of simulated gouge and their application to studies of natural fault zones.//Speed R, Sharp R eds. Proceedings of Conference VⅢ-Analysis of Actual Fault Zones in Bedrock. Virginia, WA: United States Geological Survey. Ma K F, Tanaka H, Song S R, et al. 2006. Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling Project. Nature, 144(7118): 473-476. Mitchell T M, Toy V, Di Toro G, et al. 2016. Fault welding by pseudotachylyte formation. Geology, 44(12): 1059-1062, doi: 10.1130/G38373.1. Parsons T, Ji C, Kirby E. 2008. Stress changes from the 2008 Wenchuan earthquake and increased hazard in the Sichuan basin. Nature, 454(7203): 509-510, doi: 10.1038/nature07177. Pei J L, Zhou Z Z, Dong S G, et al. 2014. Magnetic evidence revealing frictional heating from fault rocks in granites. Tectonophysics, 637: 207-217. Pei J L, Zhou Z Z, Li H B, et al. 2016. New evidence of repeated earthquakes along Wenchuan earthquake fault zone. Geology in China (in Chinese), 43(1): 43-55. Proctor B P, Lockner D. 2016. Pseudotachylyte increases the post-slip strength of faults. Geology, 44(12): 1003-1006, doi: 10.1130/G38349.1. Raj R. 1982. Creep in polycrystalline aggregates by matter transport through a liquid phase. Journal of Geophysical Research: Solid Earth, 87(B6): 4731-4739, doi: 10.1029/JB087iB06p04731. Ran Y K, Shi X, Wang H, et al. 2010. The maximum coseismic vertical surface displacement and surface deformation pattern accompanying the MS8.0 Wenchuan earthquake. Chinese Science Bulletin, 55(9): 841-850, doi: 10.1007/s11434-009-0453-3. Ran Y K, Wang H, Chen L C, et al. 2018. Late-Quaternary fault activity of the Longmen Shan fault zone—Evidence from paleoseismic trenching. Chinese Journal of Geophysics (in Chinese),61(5):1938-1948,doi:10.6038/cjg2018M0251. Shen Z K, Sun J B, Zhang P Z, et al. 2009. Slip maxima at fault junctions and rupturing of barriers during the 2008 Wenchuan earthquake. Nature Geoscience, 2(10): 718-724. Si J L, Li H B, Kuo L W, et al. 2014. Clay mineral anomalies in the Yingxiu-Beichuan fault zone from the WFSD-1 drilling core and its implication for the faulting mechanism during the 2008 Wenchuan earthquake (MW7.9). Tectonophysics, 619-620: 171-178. Tahara M, Uehira K, Shimizu H, et al. 2008. Seismic velocity structure around the Hyuganada region, Southwest Japan, derived from seismic tomography using land and OBS data and its implications for interplate coupling and vertical crustal uplift. Physics of the Earth and Planetary Interiors, 167(1-2): 19-33. Wang E Q, Kirby E, Furlong K P, et al. 2012. Two-phase growth of high topography in eastern Tibet during the Cenozoic. Nature Geoscience, 5(9): 640-645, doi: 10.1038/ngeo1538. Wang H, Li H B, Si J L, et al. 2013. The relationship between the internal structure of the Wenchuan earthquake fault zone and the uplift of the Longmenshan. Acta Petrologica Sinica (in Chinese), 29(6): 2048-2060. Wang H, Li H B, Si J L, et al. 2014. Internal structure of the Wenchuan earthquake fault zone, revealed by surface outcrop and WFSD-1 drilling core investigation. Tectonophysics, 619-620: 101-114. Wang H, Li H B, Janssen C, et al. 2015. Multiple generations of pseudotachylyte in the Wenchuan fault zone and their implications for coseismic weakening. Journal of Structural Geology, 74: 159-171, doi: 10.1016/j.jsg.2015.03.007. Wang H, Li H B, Zhang L, et al. 2018. Pseudotachylytes in the Longmen Shan fault zone and fault weakening mechanisms. Chinese Journal of Geophysics (in Chinese),61(5):1698-1714,doi:10.6038/cjg2018M0156. Wang W M, Zhao L F, Li J, et al. 2008. Rupture process of the MS8.0 Wenchuan earthquake of Sichuan, China. Chinese Journal of Geophysics (in Chinese), 51(5): 1403-1410. Wibberley C A J, Yielding G, Di Toro G. 2008. Recent advances in the understanding of fault zone internal structure: a review. Geological Society, London, Special Publications, 299(1): 5-33, doi: 10.1144/SP299.2. Xu X W, Wen X Z, Ye J Q, et al. 2008. The MS8.0 Wenchuan earthquake surface ruptures and its seismogenic structure. Seismology and Geology (in Chinese), 30(3): 597-629. Yang T, Dekkers M J, Zhang B. 2016. Seismic heating signatures in the Japan trench subduction plate-boundary fault zone: evidence from a preliminary rock magnetic ‘geothermometer’. Geophysical Journal International, 205(1): 319-331. doi: 10.1093/gji/ggw013. Yang Z X, Chen Y T, Su J R, et al. 2012. The hypocenter and origin time of the MW7.9 Wenchuan earthquake of May 12, 2008. Acta Seismologica Sinica (in Chinese), 34(2): 127-136. Zhang L, He C G. 2013. Frictional properties of natural gouges from Longmenshan fault zone ruptured during the Wenchuan MW7.9 earthquake. Tectonophysics, 594: 149-164. Zhang L, Sun Z M, Li H B, et al. 2017. Magnetic susceptibility of WFSD-2 borehole cores from the Longmenshan thrust belt and its implications for great seismic activity. Chinese Journal of Geophysics (in Chinese), 60(1): 225-239, doi: 10.6038/cjg20170119. Zhang L, Sun Z M, Li H B, et al. 2017. Rock record and magnetic response to large earthquakes within Wenchuan earthquake fault scientific drilling cores. Geochemistry, Geophysics, Geosystems, 18(5): 1889-1906, doi: 10.1002/2017GC006822. Zhang P Z, Xu X W, Wen X Z, et al. 2008. Slip rates and recurrence intervals of the Longmen Shan active fault zone, and tectonic implications for the mechanism of the May 12 Wenchuan earthquake, 2008, Sichuan, China. Chinese Journal of Geophysics (in Chinese), 51(4): 1066-1073. Zhang W, Li H B, Huang Y, et al. 2012. Lithologic characteristics and fault zone structure revealed by No.2 hole cores of the Wenchuan Earthquake Fault Zone Scientific Drilling (WFSD-2). Geological Bulletin of China (in Chinese), 31(8): 1201-1218. Zhang Y, Feng W P, Xu L S, et al. 2008. Spatio-temporal rupture process of the 2008 great Wenchuan earthquake. Science in China Series D: Earth Sciences, 52(2): 145-154. Zhao D P, Huang Z C, Umino N, et al. 2011. Structural heterogeneity in the megathrust zone and mechanism of the 2011 Tohoku-Oki earthquake (MW9.0). Geophysical Research Letters, 38(17): L17308, doi:10.1029/2011GL048408. Zheng Y, Li H B, Sun Z M, et al. 2016. New geochronology constraints on timing and depth of the ancient earthquakes along the Longmen Shan fault belt, eastern Tibet. Tectonics, 35(12): 2781-2806. 附中文参考文献 邓起东, 陈社发, 赵小麟. 1994. 龙门山及其邻区的构造和地震活动及动力学. 地震地质, 16(4): 389-403. 付碧宏, 时丕龙, 张之武. 2008. 四川汶川MS8.0大地震地表破裂带的遥感影像解析. 地质学报, 82(12): 1679-1687. 李海兵, 付小方, Van der Woerd J等. 2008a. 汶川地震(MS8.0)地表破裂及其同震右旋斜向逆冲作用. 地质学报, 82(12): 1623-1643. 李海兵, 司家亮, 潘家伟等. 2008b. 活动断裂的变形特征及其大地震复发周期的估算. 地质通报, 27(12): 19-42. 李勇, 周荣军, Densmore A L等. 2006. 青藏高原东缘龙门山晚新生代走滑挤压作用的沉积响应. 沉积学报, 24(2): 153-164. 李勇, 周荣军, 董顺利等. 2008. 汶川地震的地表破裂与逆冲-走滑作用. 成都理工大学学报(自然科学版), 35(4): 404-413. 刘栋梁, 李海兵, 李德贵等. 2015. 地表探槽断裂岩岩石磁学揭示汶川地震断裂带不同滑移机制. 地质学报,89(12): 2250-2265. 刘静, 张智慧, 文力等. 2008. 汶川8级大地震同震破裂的特殊性及构造意义. 地质学报, 82(12): 1707-1722. 裴军令, 周在征, 李海兵等. 2016. 汶川地震断裂带多次地震活动新证据. 中国地质, 43(1): 43-55. 冉勇康, 史翔, 王虎等. 2010. 汶川MS8地震最大地表同震垂直位移量及其地表变形样式. 科学通报, 55(2): 154-162. 冉勇康, 王虎, 陈立春等. 2018. 龙门山断裂带晚第四纪的大地震活动——来自古地震研究的资料. 地球物理学报,61(5):1938-1948,doi:10.6038/cjg2018M0251. 王焕, 李海兵, 司家亮等. 2013. 汶川地震断裂带结构特征与龙门山隆升的关系. 岩石学报, 29(6): 2048-2060. 王焕, 李海兵, 张蕾等. 2018. 龙门山断裂带假玄武玻璃特征及断层弱化机制的探讨. 地球物理学报,61(5):1698-1714,doi:10.6038/cjg2018M0156. 王卫民, 赵连锋, 李娟等. 2008. 四川汶川8.0级地震震源过程. 地球物理学报, 51(5): 1403-1410. 徐锡伟, 闻学泽, 叶建青等. 2008. 汶川M8.0地震地表破裂带及其发震构造. 地震地质, 30(3): 597-629. 杨智娴, 陈运泰, 苏金蓉等. 2012. 2008年5月12日汶川MW7.9地震的震源位置与发震时刻. 地震学报, 34(2): 127-136. 张蕾, 孙知明, 李海兵等. 2017. 龙门山构造带WFSD-2钻孔岩心磁化率特征及其对大地震活动的响应. 地球物理学报, 60(1): 225-239, doi: 10.6038/cjg20170119. 张培震, 徐锡伟, 闻学泽等. 2008. 2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因. 地球物理学报, 51(4): 1066-1073. 张伟, 李海兵, 黄尧等. 2012. 四川汶川地震断裂带科学钻探2号孔(WFSD-2)岩性特征和断裂带的结构. 地质通报, 31(8): 1201-1218. 张勇, 冯万鹏, 许力生等. 2008. 2008年汶川大地震的时空破裂过程. 中国科学D辑: 地球科学, 38(10): 1186-1194.
| 
