Dynamic models of downgoing plate-buoyancy driven subduction: Subduction motions and energy dissipation
Dynamic models of downgoing plate-buoyancy driven subduction: Subduction motions and energy dissipation
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DOI：
10.1016/j.epsl.2007.07.039
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发表时间：
2007-10-15
影响因子：
5.3
通讯作者：
Goes, S.
中科院分区：
文献类型：
--
作者：
Capitanio, F. A.;Morra, G.;Goes, S.
在控制板块进入地幔的路径方面，与下行板块、上覆板块、被动或主动地幔流有关的作用力是否占主导地位一直存在争议。我们调查的动力学和能量的自由俯冲系统，仅由下行板块浮力驱动，使用一个有限元模型的粘弹性板与自由表面，陷入一个被动的无界地幔表示的阻力。参数的变化，以研究软流圈，脊推，和一个被动的覆盖板的影响，俯冲板的粘度和密度的范围。这样一个单一的、自由的板块主要通过海沟后退来实现俯冲。大部分的能量耗散发生在驱动被动地幔响应。因此，板块的下沉速度是它的斯托克斯速度，由岩石圈浮力和地幔粘性决定。总俯冲速度和倾角调整，以尽量减少在岩石圈的弯曲耗散，并受到板流变学以及浮力。低粘度的软流圈和脊推动促进板块前进，增加板块倾角和降低俯冲速度，而无功被动覆盖板块的吸力和浮力减少板块倾角，从而增加俯冲和回滚速度。然而，不同参数之间的几何关系在所有模型情况下是相同的，因为板根据其斯托克斯速度下沉。因此，自由俯冲模型提供了一个参考，可用于区分的签名下行板块浮力从其他驱动力在全球编纂的俯冲参数。(c)2007 Elsevier B.V.保留所有权利。
It is much debated whether the forces associated with the downgoing plate, the overriding plate, passive or active mantle flow are dominant in controlling the paths of plates into the mantle. We investigate the dynamics and energetics for a free subduction system, driven solely by downgoing plate buoyancy, using a finite-element model of a viscoelastic plate with a free surface, sinking into a passive unbounded mantle represented by drag forces. Parameters are varied to study effects of an asthenosphere, ridge push, and a passive overriding plate, for a range of subducting plate viscosities and densities. Such a single, free plate achieves subduction mainly through trench retreat. Most of the energy dissipation occurs in driving the passive mantle response. As a result, the slab's sinking velocity is its Stokes velocity, determined by lithospheric buoyancy and mantle viscosity. The total subduction velocity and dip adjust to minimize bending dissipation in the lithosphere, and are affected by slab rheology as well as buoyancy. A low viscosity asthenosphere and ridge push facilitate plate advance, increasing plate dips and lowering subduction velocity, while suction and buoyancy of a work-free passive overriding plate decreases plate dips, thus increasing subduction and rollback velocities. However, the geometrical relation between the different parameters is the same in all model cases, because the slabs sink according to their Stokes velocity. The free subduction models thus provide a reference that can be used to distinguish the signature of downgoing plate buoyancy from that of other driving forces in global compilations of subduction parameters. (c) 2007 Elsevier B.V. All rights reserved.