亚洲大陆主要活动块体的现今构造应力数值模拟

亚洲大陆晚新生代和现代构造变形以活动地块为主要特征，表现为在统一构造格局下不同地块间具有不同的运动方式和速度。为了研究这些具有不同运动学性质块体间的相互作用以及构造变形特征，基于亚洲大陆的总体构造格局构建了二维有限元模型。根据模拟结果，对比已知GPS数据、震源机制解以及地质调查数据等，定量分析了大陆内部主要活动地块构造应力场的分布特征，并探讨了影响亚洲大陆现今构造变形特征的主要因素。结果表明：在我国的西部陆块内，由于周边一系列近EW向弧形活动构造带的存在，导致其内部次级块体运动速率的衰减，从而进一步导致应力环境的变化，由青藏中部的挤压-拉张环境逐渐转变为塔里木、天山地区的完全挤压环境；在西伯利亚地块和印度板块的联合挤压作用下，华北地块上地壳的应力表现为较弱的挤压环境，而在该种应力环境下块体内部伸展构造的成因很可能与其深部的动力学环境有关；华南地块的运动方向与台湾造山带相反，从而形成一个秦岭-大别造山带以南的较强烈的挤压-拉张区；在印度-澳大利亚板块和菲律宾俯冲板块的联合挤压作用下，巽他地块作为华南地块和印支地块的逃逸窗口，表现出以婆罗洲、南海为中心近圆弧形的弱挤压区以及环绕挤压区外缘挤压-拉张区的应力分布特征。

Numerical Modeling of Present-Day Structural Stress of Major Active Blocks in the Asian Continent

The Late Cenozoic and present-day deformation of the Asian continent is characterized by rigid motions of active blocks with different motion patterns and velocities. To research different structural deformation and interaction among these active-blocks, we establish four different finite element numerical models based on the tectonic framework of the Asian continent. By comparing the modeling result with the GPS data, focal mechanism solution and geological survey, we quantitatively explain the distribution characteristics of the principal stresses. Then, the major factors influencing the present-day deformation of the Asian continent are discussed accordingly. The results are summarized as followings. Velocity of active blocks movements in the Western China mainland was influenced by the continuous northward compression of the Indian plate gradually decreasing from south to north across a series of lithospheric-scale active tectonic zones. This kind of variety can change stress environment from compressional-tensional area in the central Tibet to completely compressional area in the Tarim basin and the Tianshan Mountain. In the model, the calculated stress of the North China block displays very weak compressional environment, but the seismicity and extensional structures extensively developed in the inner North China block. This puzzle probably means that deep dynamics cause the North China block reactive. Because of the compression between the India plate and the Philippines plate, the motion senses of the South China block and the Taiwan orogenic belt are opposite, resulting in the formation of strong compressional-tensional domain south of the Qinling-Dabie orogenic belt. As “extrusion window” of the South China and the Indochina block, the Sunda block shows particular stress distribution, which has an arc-shaped weak compressional area centered by the South China Sea and there is a relatively strong compressional-tensional area around it.