PENETRATION OF PLATES AND PLUMES THROUGH THE MANTLE TRANSITION ZONE
PENETRATION OF PLATES AND PLUMES THROUGH THE MANTLE TRANSITION ZONE
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DOI：
10.1016/0012-821x(95)00039-f
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发表时间：
1995-07-01
影响因子：
5.3
通讯作者：
DAVIES, GF
中科院分区：
文献类型：
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作者：
DAVIES, GF
要可靠评估具有负克拉佩龙斜率的相变边界是否会导致地幔对流分层，需要模型包含对板块和羽流的良好模拟。这里提出了地幔对流的数值模型，该模型结合了俯冲岩石圈板块的合理模拟和上升的低粘度地幔羽流的良好模拟，并仔细缩放到地幔的其他一阶参数。模型表明，俯冲板块和羽流头部比恒定粘度对流模型中的流动更容易穿透相变屏障，而在恒定粘度对流模型中，板块和羽流的模拟效果很差。与羽流头部相比，板块可以穿透更大范围的克拉佩龙斜坡，而羽尾的穿透能力最差。这些结果，加上最近克拉佩龙斜坡的实验室结果以及即使是弱羽尾也到达地表的观测证据，表明俯冲板块通常不会受到这种机制的强烈抵抗，并且地幔翻转的推定事件将比最近的一些恒定粘度模型中的戏剧性小得多。
Reliable evaluations of whether a phase transformation boundary with a negative Clapeyron slope will cause mantle convection to be stratified will require models to include good simulations of plates and plumes. Here numerical models of mantle convection are presented that incorporate reasonable simulations of subducting lithospheric plates and good simulations of rising low-viscosity mantle plumes, as well as being carefully scaled to other first-order parameters of the mantle. The models show that subducting plates and plume heads penetrate a phase transformation barrier more readily than does flow in constant viscosity convection models in which plates and plumes are poorly simulated. Plates can penetrate a larger magnitude of the Clapeyron slope than plume heads, with plume tails the least able to penetrate. These results, together with recent laboratory results on Clapeyron slopes and observational evidence that even weak plume tails reach the surface, suggest that subducting plates usually are not strongly resisted by this mechanism, and that putative episodes of mantle overturn would be much less dramatic than in some recent constant-viscosity models.