Buoyant hydrous mantle plume from the mantle transition zone
Buoyant hydrous mantle plume from the mantle transition zone
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来自地幔过渡带的浮力含水地幔柱
DOI：
10.1038/s41598-019-43103-y
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发表时间：
2019-04
影响因子：
4.6
通讯作者：
T. Kuritani;Q. Xia;J. Kimura;Jia Liu;K. Shimizu;T. Ushikubo;Dapeng Zhao;M. Nakagawa;S. Yoshimura
中科院分区：
文献类型：
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作者：
T. Kuritani;Q. Xia;J. Kimura;Jia Liu;K. Shimizu;T. Ushikubo;Dapeng Zhao;M. Nakagawa;S. Yoshimura
一些大陆板块内火山和大火成岩省（LIPs）的岩浆活动可能起源于地球内部深处410-660公里处地幔过渡带（MTZ）的含水地幔上涌（即羽流）。然而，岩浆活动的最终起源，即为什么地幔柱可以在MTZ产生，仍然不清楚。本文通过对长白山火山玄武岩的研究，研究了地幔柱的浮力。在长白山火山之下，我们通过地震学观测到了来自含水MTZ的地幔柱。根据对玄武岩含水率的精细测定，估计源区地幔的潜在温度为1310 ~ 1400℃，在正常上地幔温度范围内。这一观测结果表明地幔柱没有明显的过热，地幔柱上涌是由于太平洋板块在MTZ提供的水所产生的浮力。这种含水地幔柱可以解释极含水的LIP岩浆活动的形成。水最初来自一个停滞的板块，储存在MTZ，然后不管是否存在深层热羽，水都上涌。
Magmatism at some intraplate volcanoes and large igneous provinces (LIPs) in continental areas may originate from hydrous mantle upwelling (i.e. a plume) from the mantle transition zone (MTZ) at 410–660 km depths in the Earth’s deep interior. However, the ultimate origin of the magmatism, i.e. why mantle plumes could have been generated at the MTZ, remains unclear. Here, we study the buoyancy of a plume by investigating basalts from the Changbaishan volcano, beneath which a mantle plume from the hydrous MTZ is observed via seismology. Based on carefully determined water contents of the basalts, the potential temperature of the source mantle is estimated to be 1310–1400 °C, which is within the range of the normal upper mantle temperature. This observation suggests that the mantle plume did not have a significant excess heat, and that the plume upwelled because of buoyancy resulting from water supplied from the Pacific slab in the MTZ. Such a hydrous mantle plume can account for the formation of extremely hydrous LIP magmatism. The water was originally sourced from a stagnant slab and stored in the MTZ, and then upwelled irrespective of the presence or absence of a deep thermal plume.