Laboratory models of the thermal evolution of the mantle during rollback subduction
Laboratory models of the thermal evolution of the mantle during rollback subduction
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DOI：
10.1038/nature01923
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发表时间：
2003-09-04
期刊：
影响因子：
64.8
通讯作者：
Griffiths, RW
中科院分区：
文献类型：
--
作者：
Kincaid, C;Griffiths, RW
大洋岩石圈的俯冲在板块构造、地幔的热演化和地球内部与地表之间的循环过程中起着关键作用。有关俯冲带地幔流动、热条件和化学运移的信息来自弧形火山的地球化学(1-3)、地震图像(4，5)和地球动力学模型(6-10)。这项工作的大部分认为俯冲是一个二维过程，假设平行于海沟的方向变化有限。相比之下，基于观测的模型越来越倾向于与海沟迁移和具有平移运动分量的海洋板块下沉相关的三维流动(回滚)。在这里，我们报告了实验室实验的结果，这些结果揭示了在有和没有回滚组件的情况下，俯冲作用下三维地幔环流和温度结构的根本差异。如果没有回滚运动，地幔楔体中的流动是迟缓的，板块周围没有质量通量，板块边缘的升温速度快于板块中心。相反，在回滚俯冲流在下沉板块周围和下方驱动的过程中，地幔楔体内部的速度增加，并向板块中心聚焦，板块表面沿中心线加热更多。
The subduction of oceanic lithosphere plays a key role in plate tectonics, the thermal evolution of the mantle and recycling processes between Earth's interior and surface. Information on mantle flow, thermal conditions and chemical transport in subduction zones come from the geochemistry of arc volcanoes(1-3), seismic images(4,5) and geodynamic models(6-10). The majority of this work considers subduction as a two-dimensional process, assuming limited variability in the direction parallel to the trench. In contrast, observationally based models increasingly appeal to three-dimensional flow associated with trench migration and the sinking of oceanic plates with a translational component of motion(11) (rollback). Here we report results from laboratory experiments that reveal fundamental differences in three-dimensional mantle circulation and temperature structure in response to subduction with and without a rollback component. Without rollback motion, flow in the mantle wedge is sluggish, there is no mass flux around the plate and plate edges heat up faster than plate centres. In contrast, during rollback subduction flow is driven around and beneath the sinking plate, velocities increase within the mantle wedge and are focused towards the centre of the plate, and the surface of the plate heats more along the centreline.