The influence of trench migration on slab penetration into the lower mantle
The influence of trench migration on slab penetration into the lower mantle
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DOI：
10.1016/0012-821x(96)00023-4
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发表时间：
1996-05-01
影响因子：
5.3
通讯作者：
Christensen, UR
中科院分区：
文献类型：
--
作者：
Christensen, UR
利用笛卡尔几何中的二维对流数值模型，研究了沟槽迁移对俯冲板块穿透660 km深度吸热相界能力的影响。海洋板块的瞬时俯冲历史是通过在表面施加板块和海沟运动来模拟的。粘度取决于温度和深度。发现了各种类型的板的行为，主要取决于沟槽的速度。当沟槽退缩速度大于2-4 cm/a时，下降板在相界上方变平。在较慢的速度下，它直接穿透到下地幔，尽管过渡区的扁平化可能会在稍后发生，导致复杂的板片形态。板可以屈曲，与它是否穿透无关，特别是当相边界存在局部粘性增加时。扁平的板块只是暂时滞留在过渡带，并最终下沉到下地幔。这些结果为理解地震层析成像揭示的板片几何形状的变化提供了一个框架。
A two-dimensional numerical convection model in cartesian geometry is used to study the influence of trench migration on the ability of subducted slabs to penetrate an endothermic phase boundary at 660 km depth. The transient subduction history of an oceanic plate is modelled by imposing plate and trench motion at the surface. The viscosity depends on temperature and depth. A variety of styles of slab behaviour is found, depending predominantly on the trench velocity. When trench retreat is faster than 2-4 cm/a, the descending slab flattens above the phase boundary. At slower rates it penetrates straight into the lower mantle, although flattening in the transition zone may occur later, leading to a complex slab morphology. The slab can buckle, independent of whether it penetrates or not, especially when there is a localised increase in viscosity at the phase boundary. Flattened slabs are only temporarily arrested in the transition zone and sink ultimately into the lower mantle. The results offer a framework for understanding the variety in slab geometry revealed by seismic tomography.