川滇地区地壳形变动力学模式数值模拟研究综述
Review on the Study of Numerical Simulation of Crustal Deformation Dynamic Models in Sichuan-Yunnan Region
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摘要: 川滇地区位于青藏高原东南缘,其地壳形变特征一直是研究的热点问题之一,而这种形变的动力学模式的驱动机理仍存在争议。首先综述了近年来基于有限元数值模拟方法研究川滇地区动力学模式的理论成果和研究进展,旨在探讨构造块体挤压、中下地壳流、重力扩散及地幔对流作用4种动力学模式对藏东南地区现今地壳变形的影响。其中块体挤压模式聚焦于地壳变形由块体边界断裂带活动性所控制,但在川滇菱形块体西侧边界断裂带及次级断裂的选取存在争议;中下地壳流模式认为,在中下地壳存在低粘度、能够发生流动的低速体,但其规模和尺度尚无清晰结论;重力扩散模式在川滇地区的高海拔差异下作用明显,但这一过程是否有中下地壳流参与目前并不确定;上地幔在地壳底边界施加的拖曳力对地壳运动的影响也逐渐受到重视。其次讨论了现今川滇地区动力学模式有限元数值模拟方法存在的问题与挑战,需要综合考虑多种动力学模式,合理构建有限元几何和物理模型,才能厘清各类外部和内部驱动力对地壳形变的贡献。最后指出了川滇地区动力学模式数值模拟研究的发展方向,充分考虑多物理场耦合,综合应用多学科资料,在高性能计算技术的基础下有效提升算法效率和稳定性可能是今后动力学有限元数值模拟研究的趋势。Abstract: Sichuan-Yunnan region is located in the southeast margin of the Tibetan Plateau, and its crustal deformation characteristics have been one of the hot issues in the research, but the driving mechanism of the dynamic model of the deformation is still controversial. First,the theoretical results and research progress of the structural deformation model in Sichuan-Yunnan region based on the finite element numerical simulation method in recent years are reviewed, aiming to explore the influence of four tectonic models: block extrusion, middle-lower crust flow, gravity diffusion and mantle convection. The block extrusion model focuses on the crustal deformation controlled by the activity of the block boundary faults, but there are controversies in the selection of the secondary faults. The middle-lower crust flow model holds that there are weak layers with low viscosity and flow ability in deep crust, but its scale and size are still unclear. The gravity diffusion model plays an obvious role in the high altitude difference of Sichuan-Yunnan region, but it is uncertain whether the middle-lower crust flow are involved in this process. The influence of the drag force exerted by mantle convection on the bottom boundary of the lithosphere on the crustal movement has been gradually paid attention to. Second, the existing problems and challenges of finite element numerical simulation methods of dynamic models in Sichuan-Yunnan region are discussed. It is necessary to comprehensively consider all 4 types of dynamic models and reasonably construct finite element geometric and physical models in order to clarify the contribution of various external and internal driving forces to crustal deformation. Finally, the development direction of numerical simulation of dynamic model in Sichuan-Yunnan region is pointed out. Considering the coupling of multiple physical fields and the comprehensive application of multi-disciplinary data, the improvment of algorithm efficiency and stability on the basis of high performance computing technology may be the future trend of dynamic finite element numerical simulation research.