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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Water flow to the mantle transition zone inferred from a receiver function image of the Pacific slab
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Water flow to the mantle transition zone inferred from a receiver function image of the Pacific slab

机译：从太平洋板块的接收器功能图像推断到地幔过渡带的水流量

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Variations in seismic velocity near the subducting slab provide constraints on the thermal structure and the distribution of hydrous minerals and water in a subduction zone. We investigated the seismological structure in the upper mantle beneath Japan using both radial and transverse receiver functions (RFs). Radial RF can image horizontal layers of velocity contrast while transverse RF can image dipping layers. The combination allows us to simultaneously image both horizontal and dipping velocity discontinuities. We investigated the records of 45 teleseismic events observed with tiltmeters at 678 Hi-net stations. The frequency band we used is from 0.02 to 0.16 Hz. The resultant RF image shows an elevated 410 km discontinuity and, more importantly, the top surface of the Pacific slab down to below the 410 km discontinuity. With forward modeling, we determined that the mantle wedge is about 8% slower in shear-wave speed than the subducting slab at depths deeper than 200 km. The seismic velocity contrast is presumably caused by a sequence of hydrous minerals at the base of the mantle wedge which receives water released by dehydration reactions in the oceanic crust. We employed numerical simulations to determine the distribution of water in and around the subducting slab. The result suggests that hydrous minerals are continuously stable above the subducting slab in relatively cool conditions, and carry water to the mantle transition zone.
机译：俯冲平板附近地震速度的变化对俯冲带的热结构以及含水矿物质和水的分布提供了限制。我们使用径向和横向接收器功能（RF）研究了日本下方上地幔的地震学结构。径向RF可以成像速度对比的水平层，而横向RF可以成像浸渍层。这种组合使我们能够同时对水平和不连续速度不连续性进行成像。我们调查了在678个高台站用倾斜仪观测到的45次地震事件的记录。我们使用的频段为0.02至0.16 Hz。最终的RF图像显示出410 km的不连续性升高，更重要的是，太平洋板块的顶面下降到410 km的不连续性以下。通过前向建模，我们确定在200 km以上的深度中，地幔楔的剪切波速度比俯冲板慢了8％。地震速度的反差大概是由地幔楔底部的一系列含水矿物引起的，该含水矿物接收由大洋地壳中的脱水反应释放的水。我们采用数值模拟来确定俯冲板中和周围的水分布。结果表明，含水矿物质在相对凉爽的条件下在俯冲板之上连续稳定，并将水带到地幔过渡带。

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