Intraplate volcanism originating from upwelling hydrous mantle transition zone
Intraplate volcanism originating from upwelling hydrous mantle transition zone
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源自含水地幔过渡带上升流的板内火山活动
DOI：
10.1038/s41586-020-2045-y
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发表时间：
2020-02
期刊：
影响因子：
64.8
通讯作者：
Jianfeng Yang;M. Faccenda
中科院分区：
文献类型：
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作者：
Jianfeng Yang;M. Faccenda
地球上发生的大多数岩浆活动通常归因于大洋中脊的被动地幔上涌、俯冲带的板片脱挥发分或地幔柱。然而，中国东北地区广泛存在的新生代板内火山活动，以及日本海沟近海的年轻小点火山，很难与任何这些机制联系起来。此外，这些类型的火山活动下方的地幔特征是过渡带上方和下方的异常低地震速度区域， , , –（地幔层位于 410 至 660 公里之间的深度）。对这些现象缺乏全面的解释。在这里，我们表明，日本俯冲带周围的大多数（或可能全部）板内和小点火山活动和低速带可以通过俯冲太平洋板片与含水地幔过渡带的新生代相互作用来解释。数值模型表明，地幔矿物中溶解了 0.2 至 0.3 重量％的水，这些矿物是由于构造板块的俯冲和后退而从过渡带被驱赶出来的，足以重现观测结果。这表明，在该俯冲带周围的过渡带以及以板内或小点火山作用和下伏地幔低速带为特征的特提斯构造带的其他区域中，可能积累了临界量的水。
Most magmatism occurring on Earth is conventionally attributed to passive mantle upwelling at mid-ocean ridges, to slab devolatilization at subduction zones, or to mantle plumes. However, the widespread Cenozoic intraplate volcanism in northeast China, –and the young petit-spot volcanoes, , –offshore of the Japan Trench cannot readily be associated with any of these mechanisms. In addition, the mantle beneath these types of volcanism is characterized by zones of anomalously low seismic velocity above and below the transition zone, , , –(a mantle level located at depths between 410 and 660 kilometres). A comprehensive interpretation of these phenomena is lacking. Here we show that most (or possibly all) of the intraplate and petit-spot volcanism and low-velocity zones around the Japanese subduction zone can be explained by the Cenozoic interaction of the subducting Pacific slab with a hydrous mantle transition zone. Numerical modelling indicates that 0.2 to 0.3 weight per cent of water dissolved in mantle minerals that are driven out from the transition zone in response to subduction and retreat of a tectonic plate is sufficient to reproduce the observations. This suggests that a critical amount of water may have accumulated in the transition zone around this subduction zone, as well as in others of the Tethyan tectonic belt that are characterized by intraplate or petit-spot volcanism and low-velocity zones in the underlying mantle.