剥蚀及地幔作用下青藏高原隆升过程的数值模拟

NUMERICAL SIMULATION OF THE QINGHAI-XIZANG PLATEAU UPLIFT UNDER THE EFFECT OF DENUDATION AND MANTLE CONVECTION

修改了England和Mckenzie的黏性薄层流变模型中控制大陆形变的连续性方程 ,将剥蚀作用对高原隆升演化的影响直接引入该方程 ,并考虑下伏地幔小尺度对流对增厚岩石层的搬离作用对高原隆升演化后期的影响 ,用有限差分法直接模拟青藏高原隆升过程 .数值模拟结果所显示的高原隆升演化过程与实际观测资料吻合较好 ,揭示了高原隆升演化过程的非平稳和多阶段的特性 ;同时还表明上地幔小尺度对流对岩石层底部的搬离作用可能是最近8Ma以来高原快速隆升的主导机制 .

The continuity equation controlling continental deformation in the England Mckenzie's thin viscous sheet model is modified. We directly introduce the effect of denudation during the uplift process of the Qinghai Xizang plateau into the continuity equation, and consider the effect of removal caused by the small scale mantle convection beneath this region at the bottom of the thickening mantle lithsphere during late uplift period of the plateau. We use the method of finite difference to directly simulate the uplift process of the Qinghai Xizang plateau. The results are consistent with the observed data and reveal that the process of the plateau's uplift is multistage and unstable. The results also indicate that the removal caused by the small scale upper mantle convection at the bottom of the thickening mantle lithosphere may be the main mechanism of the rapid uplift of the plateau since 8Ma.