Interaction of subducted slabs with the mantle transition-zone: A regime diagram from 2-D thermo-mechanical models with a mobile trench and an overriding plate
Interaction of subducted slabs with the mantle transition-zone: A regime diagram from 2-D thermo-mechanical models with a mobile trench and an overriding plate
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DOI：
10.1002/2014gc005257
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发表时间：
2014-05-01
影响因子：
3.5
通讯作者：
Wilson, C. R.
中科院分区：
文献类型：
--
作者：
Garel, F.;Goes, S.;Wilson, C. R.
过渡带板块变形影响地球的热、化学和构造演化。然而，负责成像板形态的广泛的机制仍然存在争议。在这里，我们使用2-D的热力学模型与移动的沟槽，覆盖板，温度和应力依赖的流变学，和10，30，或100倍的增加下地幔粘度，调查的影响，初始俯冲和覆盖板年龄板过渡区的相互作用。出现了四种俯冲样式：（i）“垂直褶皱”模式，具有准静止海沟、近垂直俯冲和深部屈曲/褶皱（VF）;（ii）板片，引起温和的海沟后退，在上-下地幔界面（HD）处变平/“水平偏转”并停滞;（iii）倾斜板片，由快速下沉和强烈的海沟后退（ISR）引起;（iv）两阶段模式，显示向后弯曲和随后倾斜的板，具有晚期沟槽后退（BIR）。从体制（i）到（iii）的转变发生与俯冲板块年龄的增加（i。例如，浮力和强度）。体制（iv）发展为老（强）俯冲和覆盖板块。我们发现，沟槽运动和板变形之间的相互作用在深度决定俯冲风格，都是由板强度，这是一致的预测从以前的组合俯冲模型控制。然而，由于变形，下沉速率，温度和板片强度之间的反馈，俯冲板块浮力，覆盖板块强度，和上下地幔粘度跳跃也是重要的控制在热-机械俯冲。对于中间的上下地幔粘度跳跃（x30），我们的制度再现不同范围的地震成像板状形态。
Transition zone slab deformation influences Earth's thermal, chemical, and tectonic evolution. However, the mechanisms responsible for the wide range of imaged slab morphologies remain debated. Here we use 2-D thermo-mechanical models with a mobile trench, an overriding plate, a temperature and stress-dependent rheology, and a 10, 30, or 100-fold increase in lower mantle viscosity, to investigate the effect of initial subducting and overriding-plate ages on slab-transition zone interaction. Four subduction styles emerge: (i) a "vertical folding" mode, with a quasi-stationary trench, near-vertical subduction, and buckling/folding at depth (VF); (ii) slabs that induce mild trench retreat, which are flattened/"horizontally deflected" and stagnate at the upper-lower mantle interface (HD); (iii) inclined slabs, which result from rapid sinking and strong trench retreat (ISR); (iv) a two-stage mode, displaying backward-bent and subsequently inclined slabs, with late trench retreat (BIR). Transitions from regime (i) to (iii) occur with increasing subducting plate age (i. e., buoyancy and strength). Regime (iv) develops for old (strong) subducting and overriding plates. We find that the interplay between trench motion and slab deformation at depth dictates the subduction style, both being controlled by slab strength, which is consistent with predictions from previous compositional subduction models. However, due to feedbacks between deformation, sinking rate, temperature, and slab strength, the subducting plate buoyancy, overriding plate strength, and upper-lower mantle viscosity jump are also important controls in thermo-mechanical subduction. For intermediate upper-lower mantle viscosity jumps (x30), our regimes reproduce the diverse range of seismically imaged slab morphologies.