地幔对流对全球岩石圈应力产生与分布的作用

利用动力学模拟方法研究地幔对流对于大尺度岩石圈内部应力场形成的作用. 地幔物质内部的密度横向非均匀及表面板块运动引起地幔流动，并在岩石圈底部产生一个应力场. 该应力场作为面力将造成岩石圈本身变形，从而产生岩石圈内部的应力分布. 模拟计算结果表明，大部分俯冲带及大陆碰撞带区域应力均呈现挤压特征，如环太平洋俯冲带及印度－欧亚碰撞带等；而东太平洋洋脊、大西洋洋脊及东非裂谷处应力状态均表现为拉张；并且绝大多数热点位置处于应力拉张区域，这与目前对全球构造应力状态的理解是一致的. 计算的岩石圈内部最大水平主压应力的方向与观测表现出相当的一致，其结果总体上吻合得较好，然而在局部区域（例如西北太平洋的俯冲带、青藏高原等地区）存在着较大的差异. 研究表明，地幔对流是造成岩石圈内部大尺度应力状态及分布的一个重要因素.

Effects of mantle flow on generation and distribution of global lithospheric stress field

We apply a kinematic simulation method to perform modeling for the global lithospheric stress field induced by mantle flow. Both the internal density anomalies and surface plate movements drive the mantle circulation. Mantle flow causes normal stress and tangential stresses at the base of the lithosphere, which affect or even lead to lithospheric stress field and lithospheric deformation. Our simulation shows that the agreement between predictions and observations is good in most regions. Most subduction zones and continental collisions, such as the circum_Pacific subduction zone and the collision zone between the India and Eurasia plate, are under compression. While ocean ridges, such as the east Pacific ridge, the Atlantic ridge and the east African rift, are under tension. And hotspots preferentially occur in regions where calculated stress is tensile. Calculated directions of the maximum horizontal principal compressive stress are in accord with observed principal stress directions in the mass except for some regions such as the northwest Pacific subduction zone and the Qinghai_Tibet Plateau. Our study shows that, mantel flow plays an important role in generating and distribution of the stress field within the lithosphere.