北半球陆壳现今构造应力场分布模式——基于有限元分析

A discussion on the distribution pattern of tectonic stress field in northern hemisphere continental crust based on the finite element analysis

北半球大陆现今地貌形态是板块作用的产物,其动力学机制相当复杂,而目前尚无统一的应力分布模式。采用三维弹性有限元模型,综合考虑构造边界与地壳结构的影响,并以震源机制解作为验证手段,正演出北半球陆壳现今构造应力场。结果显示,板块边界力对区域构造应力场起主导作用,而地壳深部莫霍面与均衡面的深度差会伴生垂向构造力使局部地区应力性质发生改变。受地壳结构的影响,板块的汇聚边界、转换边界仍可存在高张应力值,地壳内部构造活动强烈地区往往差应力值较大。北半球现今地应力场是地壳长期演化的一个瞬时状态,三维弹性球壳模型模拟结果可靠,可以作为北半球陆壳构造应力场分析的定量参考模型。

The current geomorphology of the northern hemisphere continent results from plate tectonics,which manifests the complicated dynamic mechanism.However,there is no unified stress distribution pattern at present.In this paper,a three-dimensional elastic finite element model was applied to calculating the tectonic stress field in northern hemisphere continental crust by comprehensively considering the influence of tectonic boundaries and crustal structure,which was then tested by the focal mechanism solutions.The results show that the boundary force plays a key role in the regional tectonic stress field,and the depth difference between the Moho and the equilibrium interface will contribute to the vertical tectonic stress and to changing the stress properties afterwards.Influenced by the crustal structure,the convergent and transform boundaries can also partially have high tensile stress,while the tectonic active regions tend to have large differential stress values.The current stress field of the northern hemisphere is in a transient state of the long-term crustal evolution process.The simulation results of the three-dimensional elastic spherical model are reliable and can be used as a quantitative reference for the northern hemisphere tectonic stress field analysis.