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海底地形与热流观测值和岩石圈年龄的关系在小年龄段可用半无限空间冷却模型精确描述, 但在大年龄段存在显著差异. Parsons 和 McKenzie 在 20 世纪 70 年代的研究中首次将该差异归因于岩石圈下小尺度地幔对流. 随后科学家们对小尺度地幔对流问题进行了大量研究, 但结果并不一致. 本文根据建立的垂直于大洋中脊的二维热对流有限元数值模型对小尺度地幔对流对海底地形与热流的影响进行了详细研究. 该模型的主要特点是采用开放边界条件, 从而可以避免原有封闭模型因回流问题而产生的复杂效应. 数据结果显示: 对黏性与温度相关的牛顿流体, 小尺度地幔对流可造成海底表面热流的增加, 但对海底地形影响很小. 这主要是由于小尺度对流会造成两种效应: 将地幔内部热量传到岩石圈底部并加热岩石圈从而使表面热流增加; 这一效应的必然结果就是第二效应——加速地幔冷却. 由于两种效应对海底地形的影响相反, 且效果相当, 所以小尺度地幔对流对地形几乎不产生影响.
The relationship between seafloor topography and heat flux observations and lithosphere age can be accurately described in a semi-infinite space cooling model for small ages, but significantly different in older ages. Parsons and McKenzie, for the first time in a 1970s study, Due to the small-scale mantle convection in the lithosphere, a large number of studies have been conducted on the convection problems of small-scale mantle, but the results are not consistent.In this paper, based on the established two-dimensional numerical model of convective heat flow perpendicular to the mid- The influence of mantle convection on the seafloor topography and heat flow is studied in detail.The main feature of this model is that the open boundary conditions are used to avoid the complex effect caused by the backflow problem of the original closed model.The results show that the viscosity and temperature The associated Newtonian fluid and small-scale mantle convection can increase the heat flux on the surface of the seafloor, but have little effect on the seafloor topography, mainly due to the two effects of small-scale convection: transferring the heat inside the mantle to the bottom of the lithosphere and heating the rock The circle thus increases the surface heat flux; the corollary of this effect is the second effect - accelerated cooling mantle two effects have opposite influence on the seafloor topography, and the effect is quite so small scale mantle convective little impact on the terrain.