| 大陆地震构造系统: 以青藏高原及邻区为例 |
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| 引用本文： | 李德威,陈继乐,陈桂凡,梁桑.大陆地震构造系统: 以青藏高原及邻区为例[J].地球科学,2014,39(12):1763-1775. |
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| 作者姓名： | 李德威 陈继乐 陈桂凡 梁桑 |
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| 作者单位： | 1.中国地质大学地球科学学院, 湖北武汉 430074 |
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| 基金项目： | 中国地质调查局1∶5万区域地质调查，国家自然科学基金 |
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| 摘 要： | 青藏高原及邻区三角形发震构造域是全球大陆最显著的地震多发区.脆性活动断层及其弹性回跳模式无法合理解释该区深度集中分布在10~40 km的点状震源.针对发震构造和地震机理不明确这一重大科学问题, 以大陆动力学和地球系统动力学新思想为指导, 对青藏高原及邻区发震构造系统进行域、层、带、点相关研究, 阐明大陆地震构造系统的结构型式, 认为下地壳固态流变及其韧性剪切带是提供地震能量的孕震构造, 中地壳韧-脆性剪切带是累积地震能量的发震构造, 上地壳脆性断裂是释放地震能量的释震构造.在研究青藏高原及邻区地震构造系统及其形成背景的基础上, 进一步论证了大陆地震热流体撞击的形成机理: 地幔墙导致大洋中脊之下的软流圈热流物质层流到大陆特定部位汇聚加厚并底辟上升, 造成大陆下地壳部分熔融和固态流变, 并改变莫霍面的产状, 固态流变物质侧向非均匀流动, 形成大陆盆山体系, 流动的韧性下地壳与脆性上地壳之间具有韧-脆性剪切滑脱性质的中地壳不断积累由下地壳热能转换而来的应变能, 形成发震层, 震源定位于下地壳热流物质富集带("热河")中的固态-半固态流变物质撞击到强弱层块之间的构造边界, 不同热构造环境和撞击角度产生5种不同类型的地震.从而为大陆地震的科学预测奠定了全新的理论基础.
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| 关 键 词： | 地震构造系统 下地壳流动 地震机理 地震预防 青藏高原 |
| 收稿时间： | 2014-09-03 |
Continental Seismotectonic System:Example from Qinghai-Tibet Plateau and Its Adjacent Areas |
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| Li Dewei,Chen Jile,Chen Guifan,Liang Sang.Continental Seismotectonic System:Example from Qinghai-Tibet Plateau and Its Adjacent Areas[J].Earth Science-Journal of China University of Geosciences,2014,39(12):1763-1775. |
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| Authors: | Li Dewei Chen Jile Chen Guifan Liang Sang |
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| Abstract: | Triangular earthquake domain covering the Qinghai-Tibet Plateau and its adjacent areas is the most significant earthquake-prone area in the continent all overthe world. Stratiform distribution of hypocenters between 10 and 40 km can't be reasonably explained by brittle active faults and the elastic rebound model. To explore unknown seismogenic tectonics and earthquake mechanism, in this paper systematically is discussed the relationship of seismotectonic domain, seismotectonic layer, seismotectonic belt and seismotectonic point of the Qinghai-Tibet Plateau and its adjacent areas systematically is discussed based on the new understanding of continental dynamics and earth system dynamics. This paper elucidates the structural pattern of continental seismotectonic system: lower crustal ductile shear zone is the seismotectonic layer providing earthquake energy; middle crustal ductile-brittle shear zone is the hypocenter layer accumulating earthquake energy; and upper crustal brittle domain releases earthquake energy by faulting. Based on the study of seismotectonic system and tectonic settings upon the Qinghai-Tibet Plateau and its adjacent areas, in this paper further demonstrated the thermal fluid impacting mechanism is demonstrated asthenospheric laminar flow under the mid-ocean ridge driven by upwelling of the wall-like deep mantle magma transports mantle thermal energy and rheological material into continent where thickened asthenosphere diapirism results in incline of the Moho and inhomogeneous solid flow of lower continental crust from basin to mountain, the middle crustal ductile-brittle shear zone between ductile flowing lower crust and the brittle upper crust forms seismogenic layer by thermal energy-strain energy conversion. Hypocenter is located at the impacting point where abnormal flowing thermal fluid in lower crustal flow channel ("thermal river") impacts to the boundary between strong blocks (or layer) and weak blocks (or layer), and 5 different types of earthquakes are divided basen on different thermal tectonic environments and impacting angles. The new earthquake mechanism lays the theoretical foundation for scientific earthquake prediction. |
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| Keywords: | seismotectonic system lower crustal flow earthquake mechanism earthquake protection Qinghai-Tibet Plateau |
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