Saline aqueous fluid circulation in mantle wedge inferred from olivine wetting properties
Saline aqueous fluid circulation in mantle wedge inferred from olivine wetting properties
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DOI：
10.1038/s41467-019-13513-7
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发表时间：
2019-12
影响因子：
16.6
通讯作者：
Yongsheng Huang;T. Nakatani;M. Nakamura;C. McCammon
中科院分区：
文献类型：
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作者：
Yongsheng Huang;T. Nakatani;M. Nakamura;C. McCammon
最近，高导电体已被检测到的一些前弧下，被认为是存储大量的板片衍生的流体。这意味着弧前地幔楔是可渗透的含水流体。在这里，我们精确地确定在弧前地幔条件下的橄榄石-NaCl-H2O系统的二面角（润湿）角，以评估俯冲带流体的盐度对流体连通性的影响。我们发现，NaCl显着降低二面角低于60°，在所有研究的条件下，浓度高于5重量%，重要的是，甚至在1重量%，在2 GPa。我们的研究结果表明，板释放流体形成一个互联的网络在相对较浅的深度约80公里，可以部分到达弧前地壳，而不会引起地幔的湿熔融和蛇纹化。通过地幔楔的渗透窗口的流体输送占在弧前地区检测到的高电导率异常的位置。
Recently, high electrical conductors have been detected beneath some fore-arcs and are believed to store voluminous slab-derived fluids. This implies that the for-arc mantle wedge is permeable for aqueous fluids. Here, we precisely determine the dihedral (wetting) angle in an olivine–NaCl–H2O system at fore-arc mantle conditions to assess the effect of salinity of subduction-zone fluids on the fluid connectivity. We find that NaCl significantly decreases the dihedral angle to below 60° in all investigated conditions at concentrations above 5 wt% and, importantly, even at 1 wt% at 2 GPa. Our results show that slab-released fluid forms an interconnected network at relatively shallow depths of ~80 km and can partly reach the fore-arc crust without causing wet-melting and serpentinization of the mantle. Fluid transport through this permeable window of mantle wedge accounts for the location of the high electrical conductivity anomalies detected in fore-arc regions.