南海中央海盆岩石圈纵向演化模拟

A VERTICAL EVOLUTION OF LITHOSPHERE OF THE CENTRAL BASIN OF SOUTH CHINA SEA

基于南海海盆的地质构造历史、地球物理和构造应力场资料建立准三维有限元模型,对南海中央海盆进行岩石圈纵向演化动力学模拟。本文采用弹塑性各向同性连续岩石介质模型,充分考虑拉伸速率、拉伸位移以及模型参数对模拟结果的影响,共建立了3个模型进行比较。从数值模拟结果可以看出中央海盆在被动拉张的地质构造背景下是单向生长的,动态模拟出南海中央海盆在形成过程中的陆缘裂离、海底扩张两个阶段的岩石圈纵向演化过程,并且分析了两个阶段岩石圈的动力学性质。提出水平的被动拉张力是南海岩石圈纵向演化前两个阶段形成的主要因素,并且在这两个阶段中,岩石圈的纵向演化时间主要集中在海底扩张阶段。

Based on the tectonic evolution history, the geophysical data, and the geotectonic stress field data, the dynamic simulation about the vertical evolution of lithosphere is built on a pseudo 3D finite element model. Three models are built. The property of rock is isotropy-elasto-plastic. The conditions, which include stretch spread, stretch displace, and model parameter, are researched on simulational result. The result shows that the central basin is of single direction stretch with passive stretch on geotectonic stress field. The two stages of vertical evolution process of lithosphere, which are the marginal rifting stage and seafloor spreading stage, are dynamically simulated and analyzed in the article. The authors think that the level passive stretch is the main factor in the vertical evolution history of lithosphere in the South China Sea region, and the time of evolution is focused on the seafloor spreading stage.