Roles of Hydrous Lithospheric Mantle in Deep Water Transportation and Subduction Dynamics
Roles of Hydrous Lithospheric Mantle in Deep Water Transportation and Subduction Dynamics
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DOI：
10.1029/2017gl076953
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发表时间：
2018-06
影响因子：
5.2
通讯作者：
A. Nakao;H. Iwamori;T. Nakakuki;Yujiro J. Suzuki;Hitomi Nakamura
中科院分区：
文献类型：
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作者：
A. Nakao;H. Iwamori;T. Nakakuki;Yujiro J. Suzuki;Hitomi Nakamura
我们使用二维模拟来研究含水岩石圈地幔（HLM）对俯冲动力学的影响。结果表明，俯冲HLM的厚度强烈控制会聚板块的运动和变形。当HLM厚度低于临界值时，例如，对于100 Ma的板片，HLM中的所有蛇纹石分解，并且释放的流体进入地幔楔。流体削弱了上覆的板块，导致海沟后退，板块快速聚合，板块停滞。相反，当HLM厚度超过临界值时，在高压下，致密的含水硅酸镁出现在HLM的冷部分。有浮力的致密含水镁硅酸盐降低了板块拉力，削弱了海沟后退、快速收敛和板块停滞。低的HLM厚度可以解释一些实际俯冲带的构造，这些俯冲带的特征是海沟后退、快速收敛和停滞板，例如日本东北部。
We used two‐dimensional simulations to investigate the effects of a hydrous lithospheric mantle (HLM) on subduction dynamics. It was demonstrated that the thickness of a subducting HLM strongly controls the motion and deformation of converging plates. When the HLM thickness is lower than a critical value, for example, ∼5 km for a 100‐Ma slab, all serpentine in the HLM decomposes, and the liberated fluid enters the mantle wedge. The fluid weakens the overlying plate, causing trench retreat, rapid plate convergence, and slab stagnation. In contrast, when the HLM thickness exceeds the critical value, dense hydrous magnesium silicates appear in cold parts of the HLM at high pressures. The buoyant dense hydrous magnesium silicates reduce the slab pull force, weakening trench retreat, rapid convergence, and slab stagnation. A low HLM thickness may account for tectonics in some actual subduction zones characterized by trench retreat, rapid convergence, and stagnant slabs, for example, in Northeast Japan.