青藏高原低速层对岩石圈强度影响的三维有限元模拟
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摘要
采用三维多层壳结构单元,用有限元法计算了青藏高原岩石圈在地形载荷下的挠曲变形;并基于地震波速度模型和莫霍面深度约束模型所得到的高原岩石圈分层的力学模型,就高原整体、东部及西部块体的热物质低速层对高原岩石圈强度的影响进行了研究。计算结果表明,热物质低速层对整个东、西块体地壳强度有着不同程度的影响,它对东部区域的影响比西部大。
The downward deflection of the Qinghai-Tibet lithosphere due to the topographical load is calculated with finite element method by use of the 3D multilayered shell structural unit.Then,the influence of the lower-velocity layer of thermokarst on the intensity of the Qinghai-Tibet lithosphere in different regions is studied with multilayered mechanical model,based on the seismic-wave velocity structural model and the constrained Moho model.The results show that the lower-velocity layer of thermokarst has a stronger influence on the lithosphere in the eastern region of the Qinghai-Tibet plateau than that in the western region.
The downward deflection of the Qinghai-Tibet lithosphere due to the topographical load is calculated with finite element method by use of the 3D multilayered shell structural unit.Then,the influence of the lower-velocity layer of thermokarst on the intensity of the Qinghai-Tibet lithosphere in different regions is studied with multilayered mechanical model,based on the seismic-wave velocity structural model and the constrained Moho model.The results show that the lower-velocity layer of thermokarst has a stronger influence on the lithosphere in the eastern region of the Qinghai-Tibet plateau than that in the western region.
引文
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17Sato H and Sacks I S.The use of laboratory velocity datafor estimating tem perature and partial melt fraction in thelow-velocity zone[J].J Geophys Res,1989,94:5689-5704.
18Muellor H J and Raab S.Elastic wave velocities of graniteat experimental simulated partial melting conditions[J].Phys Chem Earth,l997,22:93-96.
19Alsdorf D,et al.Crustal deformation of the Lhasa terrane,Tibet plateau from Project INDEPTHdeep seismic reflectionprofiles[J].Tectonics,1998,17(4):501-519.
20Shengbiao Hu,Lijuan He,Jiyang Wang.Heat flow in thecontinental area of China:a new data set[J].Earth andPlanetary Science Letters,2000,179:407-419.
2Braitenberg C,Wang Y,Fang J and Hsu HT.Spatial varia-tions of flexure parmeters over the Tibert-Qinghai plateau[J].Earth and Planetary Science Letters,2003,205:211-224.
3崔作舟.青藏高原地壳的伸缩及其力学性质[J].地质力学学报,1999,5(3):8～12.3Cui Zuozhou.Crustal extension shortening of Qinghai Tibetplateau and mechanical properties implications[J].Journalof Geomechanics,1999,5(3):8-12.(in Chinese)
4Mckenzie D and Fairhead D.Estimates of the effective elas-tic thickness of the continental lithosphere from Bouguer andfree air gravity anomalies[J].J.Geophys.Res,1997,102:27523-27552.
5Burov E B and Diament M.Flexure of the continental litho-sphere with multilayered rhelogy[J].Geophys.J.Int,1992,109:449-468.
6Burov E B and Diament M.The effective elastic thickness ofcontinental lithosphere:What does it really mean?[J].J.Geophys.Res,1993,100:3905-3927.
7Jin Y,McNutt MKand Zhu Y S.Evidence from gravity andtopography data for folding of Tibet[J].Nature,1994,371:669-674.
8Jin Y,McNutt M K and Zhu Y S.Mapping the descent ofIndian and Eurasian plates beneath the Tibetan Plateau fromgravity anomalies[J].J.Geophys.Res,1996,101:11275-11290.
9滕吉文,熊绍柏,等.喜马拉雅北部地区的地壳结构模型和速度分布特征[J].地球物理学报,1983,26(4):525～540.9Teng Jiwen,Xiong Shaobai,et al.Structure of the crust andupper mantle pattern and velocity distributional characteris-tics in the Northern Himalayan mountain region[J].ChineseJ.Geophys.(Acta Geophysica Sinica),1983,26(6):525～540.(in Chinese)
10杨红心,等.青藏高原隆升的非线性动态有限元仿真研究[J].大地测量与地球动力学,2002,22(2):75～81.10Yang Hongxin,et al.Research on up-lift of Qinghai-Tibetplateau by non-linear dynamical finite element method[J].Journal of Geodesy and Geodynamics,2002,22(2):75-81.(in Chinese)
11张先,赵丽.青藏高原航磁异常及居里面研究[J].大地测量与地球动力学,2003,23(4):14～20.11Zhang Xian and Zhao Li.Curie surface and aeromagetic a-nomaly in Qinghai-Tibet plateau[J].Journal of Geodesyand Geodynamics,2003,23(4):14-20.(in Chinese)
12柯小平,等.青藏东缘Moho界面的位场遗传算法反演[J].大地测量与地球动力学,2006,26(1):100～104.12Ke Xiaoping,et al.3D Moho depth inversion of eastern Ti-betan plateau from gravity data with genetic algorithm[J].Journal of Geodesy and Geodynamics,2006,26(1):100-104.(in Chinese)
13王辉,等.青藏活动地块区运动与变形特征的数值模拟[J].大地测量与地球动力学,2006,26(2):15～23.13Wang Hui,et al.Numerical simulation of movement and de-formation of Qinghai-Tibet plateau[J].Journal of Geodesyand Geodynamics,2006,26(2):15-23.(in Chinese)
14袁果田,张永军.青藏高原均衡重力异常研究[J].地壳形变与地震,1997,17(1):76～80.14Yuan Guotian and Zhang Yongjun.Discussion on isostaticgravity anomaly in Qinghai-Tibet plateau[J].Crustal De-formation and Earthquake,1997,17(1):76-80.(in Chi-nese)
15王勇,柯小平.重力和地震资料反演青藏高原地壳的变密度模型[A].张中杰等主编.中国大陆地球深部结构与动力学研究[C].北京:科学出版社,2004.15Wang Yong and Ke Xiaoping.Inversion of variable densitymodel from gravity and seismic data in Tibetan plateau[A].Zhang Zhongjie,et al.Research on deep structureand geodynamics of China continental[C].Beijing:Sci-ence Press,2004.(in Chinese)
16王勇,许厚泽.青藏高原印度板块向欧亚大陆俯冲速率的研究——GPS观测资料的反演结果[J].地球物理学报,2003,46(2):185～190.16Wang Yong and Xu Houze.A study on convergence rate ofthe India plate to Eruasia subduction beneath Qinhai-Xizangplateau——inversion results from GPS observational data[J].Chinese J.Geophys.(Acta Geophysica Sinica),2003,46(2):185-190.(in Chinese)
17Sato H and Sacks I S.The use of laboratory velocity datafor estimating tem perature and partial melt fraction in thelow-velocity zone[J].J Geophys Res,1989,94:5689-5704.
18Muellor H J and Raab S.Elastic wave velocities of graniteat experimental simulated partial melting conditions[J].Phys Chem Earth,l997,22:93-96.
19Alsdorf D,et al.Crustal deformation of the Lhasa terrane,Tibet plateau from Project INDEPTHdeep seismic reflectionprofiles[J].Tectonics,1998,17(4):501-519.
20Shengbiao Hu,Lijuan He,Jiyang Wang.Heat flow in thecontinental area of China:a new data set[J].Earth andPlanetary Science Letters,2000,179:407-419.
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