青藏高原东南缘构造应力场重构
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摘要
采用有限元方法,针对青藏高原东南缘建立更细致、更精确的三维有限元弹性模型。选取9种不同的应力边界条件,分别进行优化分析后处理,将对应台站形变模拟值与GPS实测值进行误差分析,最终选取最佳方案作为古构造应力场。结果表明,青藏高原东南缘4 Ma BP的古应力场主要起源于中国大陆周围板块的相互作用,特别是印度板块NNE向强烈碰撞作用,成为中国大陆尤其是西南部青藏高原地区构造应力场最主要的动力来源,控制各个块体相互作用的方式和运动格局。青藏高原东南缘古应力场主要包括几个力源:西北部青藏高原侧向挤压造成的WE向应力约105 MPa;西南部直接来自于印度板块的NE-WS向应力约70 MPa;南部NS向作用力33 MPa;东南部扬子块体侧向NW-SE阻挡力56 MPa;北东部受扬子块体强烈EW向阻挡力90 MPa。这些力源共同作用于青藏高原东南缘,形成现今复杂应力场。
Using finite element method on the southeast margin of the Tibetan plateau, this paper establishes a more detailed and accurate three dimensional finite element model of elastic, selects the stress of the nine different boundary conditions, applies optimization analysis for each project in post-processing, analyzes the corresponding station deformation GPS simulated values and measured error, and finally chooses the best solution as palaeotectonic stress field. Results show that around four million years ago the ancient stress field of the southeast margin of Tibetan plateau mainly originated from intense collision of the Indian plate NNE with the Chinese mainland plate. The mainland of China, especially the Tibetan plateau in southwest region, is the main power source of the tectonic stress field, and controls how the various blocks interact and their motion patterns. The paleostress field on the southeastern edge of the Tibet plateau mainly includes the following sources: The NE-WS directional stress in the southwest is about 70 MPa directly from the Indian plate. Southern NS force 33 MPa; lateral NW-SE blocking force of southeast Yangtze block is 56 MPa. At the same time, the strong EW blocking force of the Yangtze block in the eastern north is 90 MPa, and these forces act together on the southeastern edge of the Tibetan plateau, forming a complex stress field.
Using finite element method on the southeast margin of the Tibetan plateau, this paper establishes a more detailed and accurate three dimensional finite element model of elastic, selects the stress of the nine different boundary conditions, applies optimization analysis for each project in post-processing, analyzes the corresponding station deformation GPS simulated values and measured error, and finally chooses the best solution as palaeotectonic stress field. Results show that around four million years ago the ancient stress field of the southeast margin of Tibetan plateau mainly originated from intense collision of the Indian plate NNE with the Chinese mainland plate. The mainland of China, especially the Tibetan plateau in southwest region, is the main power source of the tectonic stress field, and controls how the various blocks interact and their motion patterns. The paleostress field on the southeastern edge of the Tibet plateau mainly includes the following sources: The NE-WS directional stress in the southwest is about 70 MPa directly from the Indian plate. Southern NS force 33 MPa; lateral NW-SE blocking force of southeast Yangtze block is 56 MPa. At the same time, the strong EW blocking force of the Yangtze block in the eastern north is 90 MPa, and these forces act together on the southeastern edge of the Tibetan plateau, forming a complex stress field.
引文
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[9] 马宏生.川滇地区强震孕育的深部动力环境研究[D].北京:中国地震局地球物理研究所,2007(Ma Hongsheng.Study on the Deep Dynamic Environment of Strong Earthquakes of Sichuan-Yunnan Region[D].Beijing:Institute of Geophysics,CEA,2007)
[10] 徐锡伟,闻学泽,郑荣章,等.川滇地区活动块体最新构造变动样式及其动力来源[J].中国科学D辑:地球科学,2003,33(增1):151-162(Xu Xiwei,Wen Xueze,Zheng Rongzhang,et al.The Latest Tectonic Change Pattern and Its Dynamic Source of Active Blocks in the Sichuan-Yunnan Region[J].Science in China Series D:Earth Sciences,2003,33(S1):151-162)
[11] 张竹琪,张培震,王庆良.龙门山高倾角逆断层结构与孕震机制[J].地球物理学报,2010,53(9):2 068-2 082(Zhang Zhuqi,Zhang Peizhen,Wang Qingliang.The Structure and Seismogenic Mechanism of Longmenshan High Dip-Angle Reverse Fault[J].Chinese Journal of Geophysics,2010,53(9):2 068-2 082)
[12] 杨兴悦,陈连旺,杨立明,等.巴颜喀拉块体强震动力学过程数值模拟[J].地震学报,2013,35(3):304-314(Yang Xingyue,Chen Lianwang,Yang Liming,et al.Numerical Simulation on Strong Earthquake Dynamic Process of Bayan Har Block[J].Acta Seismologica Sinica,2013,35(3):304-314)
[13] 李红.构造应力场、活动断裂及区域地震活动性的数值模拟研究[D].北京:中国地震局地壳应力研究所,2008(Li Hong.Numerical Simulation on Tectonic Stress Field,Active Fault and Regional Seismicity[D].Beijing:Institute of Crustal Dynamics,CEA,2008)
[14] 李玉江,陈连旺,陆远忠,等.汶川地震的发生对周围断层稳定性影响的数值模拟[J].地球科学——中国地质大学学报,2013,38(2):398-410(Li Yujiang,Chen Lianwang,Lu Yuanzhong,et al.Numerical Simulation of the Influences of Wenchuan Earthquake on the Stability of Faults in the neighborhood[J].Earth Science—Journal of China University of Geosciences,2013,38(2):398-410)
[15] 陈化然,陈连旺,马宏生,等.川滇地区应力场演化与强震间相互作用的三维有限元模拟[J].地震学报,2004,26(6):567-575(Chen Huaran,Chen Lianwang,Ma Hongsheng,et al.3-D Finite Element Modeling for Evolution of Stress Field and Interaction among Strong Earthquakes in Sichuan-Yunnan Region[J].Acta Seismologica Sinica,2004,26(6):567-575)
[2] Molnar P,Tapponnier P .Cenozoic Tectonics of Asia:Effects of a Continental Collision:Features of Recent Continental Tectonics in Asia Can Be Interpreted as Results of the India-Eurasia Collision[J].Science,1975,189(4 201):419-426
[3] 鄢家全,时振梁,汪素云,等.中国及邻区现代构造应力场的区域特征[J].地震学报,1979,1(1):9-24(Yan Jiaquan,Shi Zhenliang,Wang Suyun,et al.Some Features of the Recent Tectonic Stress Field of China and Environs[J].Acta Seismologica Sinica,1979,1(1):9-24)
[4] 邓起东,张裕明,许桂林,等.中国构造应力场特征及其与板块运动的关系[J].地震地质,1979,1(1):11-22(Deng Qidong,Zhang Yuming,Xu Guilin,et al.On the Tectonic Stress Field in China and Its Relation to Plate Movement[J].Seismology and Geology,1979,1(1):11-22)
[5] 罗灼礼.印度洋板块向北顶撞与我国西部及其邻区现代构造应力场和地震活动的关系[J].地震工程学报,1979,1(4):11-21(Luo Zhuoli.The Relationship between the Northward Collision of the Indian Ocean Plate and the Modern Tectonic Stress Field and Seismic Activity in the Western Part of China and Its Adjacent Areas [J].Journal of Earthquake Engineering,1979,1(4):11-21)
[6] 阚荣举,张四昌,晏凤桐,等.我国西南地区现代构造应力场与现代构造活动特征的探讨[J].地球物理学报,1977,20(2):96-109(Kan Rongju,Zhang Sichang,Yan Fengtong,et al.Present Tectonic Stress Field and Its Relation to the Characteristics of Recent Tectonic Activity in Southwest China[J].Chinese Journal of Geophysics,1977,20(2):96-109)
[7] 许忠淮,汪素云,黄雨蕊,等.由多个小震推断的青甘和川滇地区地壳应力场的方向特征[J].地球物理学报,1987,30(5):476-486(Xu Zhonghuai,Wang Suyun,Huang Yurui,et al.Directional Characteristics of the Crustal Stress Field in the Southeastern Margin of Qinggan and Qinghai-Tibet Plateau Inferred from Multiple Small Earthquakes [J].Chinese Journal of Geophysics,1987,30(5):476-486)
[8] 钟继茂,程万正.由多个地震震源机制解求川滇地区平均应力场方向[J].地震学报,2006,28(4):337-346(Zhong Jimao,Cheng Wanzheng.Determination of Directions of the Mean Stress Field in Sichuan-Yunnan Region from a Number of Focal Mechanism Solutions[J].Acta Seismologica Sinica,2006,28(4):337-346)
[9] 马宏生.川滇地区强震孕育的深部动力环境研究[D].北京:中国地震局地球物理研究所,2007(Ma Hongsheng.Study on the Deep Dynamic Environment of Strong Earthquakes of Sichuan-Yunnan Region[D].Beijing:Institute of Geophysics,CEA,2007)
[10] 徐锡伟,闻学泽,郑荣章,等.川滇地区活动块体最新构造变动样式及其动力来源[J].中国科学D辑:地球科学,2003,33(增1):151-162(Xu Xiwei,Wen Xueze,Zheng Rongzhang,et al.The Latest Tectonic Change Pattern and Its Dynamic Source of Active Blocks in the Sichuan-Yunnan Region[J].Science in China Series D:Earth Sciences,2003,33(S1):151-162)
[11] 张竹琪,张培震,王庆良.龙门山高倾角逆断层结构与孕震机制[J].地球物理学报,2010,53(9):2 068-2 082(Zhang Zhuqi,Zhang Peizhen,Wang Qingliang.The Structure and Seismogenic Mechanism of Longmenshan High Dip-Angle Reverse Fault[J].Chinese Journal of Geophysics,2010,53(9):2 068-2 082)
[12] 杨兴悦,陈连旺,杨立明,等.巴颜喀拉块体强震动力学过程数值模拟[J].地震学报,2013,35(3):304-314(Yang Xingyue,Chen Lianwang,Yang Liming,et al.Numerical Simulation on Strong Earthquake Dynamic Process of Bayan Har Block[J].Acta Seismologica Sinica,2013,35(3):304-314)
[13] 李红.构造应力场、活动断裂及区域地震活动性的数值模拟研究[D].北京:中国地震局地壳应力研究所,2008(Li Hong.Numerical Simulation on Tectonic Stress Field,Active Fault and Regional Seismicity[D].Beijing:Institute of Crustal Dynamics,CEA,2008)
[14] 李玉江,陈连旺,陆远忠,等.汶川地震的发生对周围断层稳定性影响的数值模拟[J].地球科学——中国地质大学学报,2013,38(2):398-410(Li Yujiang,Chen Lianwang,Lu Yuanzhong,et al.Numerical Simulation of the Influences of Wenchuan Earthquake on the Stability of Faults in the neighborhood[J].Earth Science—Journal of China University of Geosciences,2013,38(2):398-410)
[15] 陈化然,陈连旺,马宏生,等.川滇地区应力场演化与强震间相互作用的三维有限元模拟[J].地震学报,2004,26(6):567-575(Chen Huaran,Chen Lianwang,Ma Hongsheng,et al.3-D Finite Element Modeling for Evolution of Stress Field and Interaction among Strong Earthquakes in Sichuan-Yunnan Region[J].Acta Seismologica Sinica,2004,26(6):567-575)
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