The influences of lower mantle viscosity stratification on 3D spherical-shell mantle convection
The influences of lower mantle viscosity stratification on 3D spherical-shell mantle convection
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DOI：
10.1016/0012-821x(95)00038-e
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发表时间：
1995-05
影响因子：
5.3
通讯作者：
Shuxia Zhang;David A. Yuen
中科院分区：
文献类型：
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作者：
Shuxia Zhang;David A. Yuen
本文利用三维Boussinesq球壳对流模式研究了粘滞系数分层分布对时变地幔环流的动力学影响。这一特殊的粘度剖面是由大地水准面反演得到的，它具有在中下地幔存在一个大的粘度极大值的显著特征。表面瑞利数在5 × 104 ~ 8 × 106之间。有几个明显的差异，无论是羽流的形态和下沉电流从恒定粘度模型。在粘性分层的下地幔中，地幔柱总是在冷的下降流到达底部之后才形成。地幔的平均温度降低，这使得非常冷的物质下沉到地幔深处。上升流羽流的数量减少，整体环流稳定，发展出组织良好的三重连接的冷面。内部加热的存在增加了上升流羽流的数量并破坏了下降流片的网络。这些羽流变得更大的规模和有一个更热的内部，因为几乎静止的字符。
We have studied the dynamical effects of a stratified viscosity profile on time-dependent mantle circulations by using a 3D Boussinesq spherical-shell convection model. This particular viscosity profile, taken from the inversion of geoid data, has the distinct feature of having a large viscosity maximum in the middle lower mantle. Surface Rayleigh numbers ranging from 5 × 104to 8 × 106have been considered. There are several distinct differences in both the morphologies of the plumes and the sinking currents from constant viscosity models. In a viscously-stratified lower mantle, plumes are formed invariably only after the cold downwelling has reached the bottom. The mean mantle temperature is reduced and this allows for the sinking of very cold material into the deep mantle. The number of upwelling plumes is reduced and the overall circulation is stabilized, with well-organized triple junctions of cold sheets developed. The presence of internal heating increases the number of upwelling plumes and breaks up the network of downwelling sheets. These plumes become larger in size and have a hotter interior because of the nearly stationary character.