南海海盆扩张机制的动力学模拟
发布时间：2018-12-28 07:24
【摘要】：南海处于印度—澳大利亚、欧亚和太平洋三大板块汇聚中心,地理位置独特,地质作用复杂,经历了拉张、张裂到海底扩张的演化过程,是水平拉张和地幔上涌共同作用下的被动扩张结构。以南海中央海盆的地质构造为背景建立二维有限元模型,对具有先存薄弱带情况下岩石圈在水平拉张力和上涌力共同作用下的减薄扩张情况进行动力学模拟。计算结果表明:(1)岩石圈在受到拉张作用时,薄弱带和断层的存在会使该区域发生应力集中,优先减薄破坏;(2)岩石圈在单纯的拉张力条件下很难发生破坏,如果同时施加一个较小地幔上涌力反而能引起较大的变形,说明地幔上涌力在海盆扩张中起着重要的作用;(3)由于下地壳的流变性,下地壳比上地壳发生了更大程度的减薄,而且下地壳的流变特性比薄弱带的存在更有助于海盆的扩张。
[Abstract]:The South China Sea is located in the three major convergence centers of Indo-Australian, Eurasian and Pacific plates. It has a unique geographical location and complex geological processes, and has undergone an evolutionary process of stretching and fracture to undersea expansion. It is a passive spreading structure under the action of mantle upwelling. Based on the geological structure of the central basin of the South China Sea, a two-dimensional finite element model is established to simulate the thinning and spreading of the lithosphere under the combined action of horizontal tension and upwelling force in the case of pre-existing weak zone. The results show that: (1) when the lithosphere is subjected to tension, the existence of weak zones and faults will lead to stress concentration in the area and preferential thinning and failure; (2) it is difficult to destroy the lithosphere under the condition of simple tension. If a small mantle upwelling force is applied at the same time, it can cause a large deformation, which indicates that the mantle upwelling force plays an important role in the expansion of the ocean basin. (3) because of the rheological variation of the lower crust, the lower crust is thinned more than the upper crust, and the rheological characteristics of the lower crust are more helpful to the expansion of the basin than the existence of the weak zone.
【作者单位】： 中国科学院边缘海地质重点实验室南海海洋研究所;中国科学院大学;
【基金】：国家自然科学基金项目(41376061;91428205)
【分类号】：P736.1
本文编号：2393669
[Abstract]:The South China Sea is located in the three major convergence centers of Indo-Australian, Eurasian and Pacific plates. It has a unique geographical location and complex geological processes, and has undergone an evolutionary process of stretching and fracture to undersea expansion. It is a passive spreading structure under the action of mantle upwelling. Based on the geological structure of the central basin of the South China Sea, a two-dimensional finite element model is established to simulate the thinning and spreading of the lithosphere under the combined action of horizontal tension and upwelling force in the case of pre-existing weak zone. The results show that: (1) when the lithosphere is subjected to tension, the existence of weak zones and faults will lead to stress concentration in the area and preferential thinning and failure; (2) it is difficult to destroy the lithosphere under the condition of simple tension. If a small mantle upwelling force is applied at the same time, it can cause a large deformation, which indicates that the mantle upwelling force plays an important role in the expansion of the ocean basin. (3) because of the rheological variation of the lower crust, the lower crust is thinned more than the upper crust, and the rheological characteristics of the lower crust are more helpful to the expansion of the basin than the existence of the weak zone.
【作者单位】： 中国科学院边缘海地质重点实验室南海海洋研究所;中国科学院大学;
【基金】：国家自然科学基金项目(41376061;91428205)
【分类号】：P736.1
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