智利三联点南部含洋脊海洋板块俯冲过程的数值模拟

“三联点”是全球板块运动系统的重要组成部分.扩张的智利洋脊向南美板块俯冲形成了智利三联点，并造成了智利三联点以南数百千米范围内剧烈的地形变化.智利三联点区域的初始板块俯冲角度、洋脊扩张速率等因素的差异对南美板块岩石层热结构及地形起伏造成了显著影响.本文采用有限差分方法，构建了智利三联点区域洋脊俯冲的二维数值模型，模拟洋脊俯冲的动力学过程，探究扩张洋脊俯冲过程中的岩石层变形机制、地表热流的分布特征及其影响因素.结果表明，与俯冲速率相比，俯冲角度对地表热流的影响相对较大，较小俯冲角度（15°）情况下的计算热流分布与基于观测点的插值数据较为吻合，并且俯冲速率越大，上覆板块岩石层温度异常区的水平长度越大，其距海沟的距离最大可至190 km.我们的模拟结果支持智利三联点南部南极洲板块以低角度俯冲至南美大陆板块下方的观点.

Numerical simulation of the subduction process of oceanic plate with ridges in the southern part of the Chile triple junction

The "triple junction" is an important part of the global plate movement system. The expanding Chilean ridge subducted into the South American plate to form the Chile triple junction and caused drastic topographical changes within a few hundred kilometers in the south of the Chile triple junction. The differences in factors such as the initial angle of plate subduction and the rate of expansion of ocean ridges in the Chile triple junction have a significant impact on the thermal structure and topographical fluctuations of the South American plate lithosphere. In this paper, using the finite difference method, a two-dimensional numerical model of oceanic ridge subduction in Chile's triple junction area is constructed to simulate the dynamic process of oceanic ridge subduction, and to explore the mechanism of rock layer deformation, the distribution characteristics of surface heat flow during the subduction of expanding oceanic ridges and influencing factors. The results show that, compared with the subduction velocity, the subduction angle has a relatively greater impact on the surface heat flow. The calculated heat flow distribution at a smaller subduction angle (15°) is more consistent with the interpolation data based on observation points. The greater the subduction rate, the larger the horizontal length of the temperature anomaly area of the overlying slab rock layer is. The maximum distance from the trench is 190 km. Our simulation results support the viewpiont that the southern Antarctic plate near the Chile triple junction with a low dip angle subducts to the bottom of the South American continental plate.