Origin and Distribution of Geofluids and Their Roles on Geodynamics
Origin and Distribution of Geofluids and Their Roles on Geodynamics
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DOI：
10.5026/jgeography.128.761
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
H. Iwamori;Y. Yukutake;Y. Iio;Hitomi Nakamura
中科院分区：
文献类型：
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作者：
H. Iwamori;Y. Yukutake;Y. Iio;Hitomi Nakamura
总共有1到10个海洋质量的水（包括气态、液态和固态的H2O、OH、H）可能以各种形式和成分储存在地球的壳幔系统中。其中，液相包括水溶液、含水熔体和超临界流体，其可以在第二临界终点以上从稀释的含水流体连续地改变组成为硅酸盐熔体。这些流体被称为“地质流体”在这篇评论文章中，它描述了地质流体的存在所需的物理化学条件，其组成，以及相关的构造环境和地球动力学现象。根据壳幔岩石最大可储存水含量，讨论了富含固体成分的板片流体在俯冲带过程中的重要作用：地幔楔的粘流-热场和熔融作用，以及深源流体如Arimatype卤水的起源。地球物理和地球化学观测可以捕捉到弧壳中的流体通量，如地震活动性、地震速度、电导率和氦同位素比值。迁移性地震事件和局部地壳变形等若干具体现象可归因于这种来自深处的流体流动，而这种流动是由于流体压力升高以及岩石强度和粘度降低而引起的。
A total of one to ten ocean masses of water (including H2O, OH, H in gas, liquid, and solid phases) is probably stored in the Earth’s crust-mantle system as a variety of forms and components. Of these, the liquid phase involves aqueous solution, hydrous melt, and supercritical fluid, which may change composition continuously from a diluted aqueous fluid to a silicate melt above the second critical endpoint. These fluids are termed “geofluids” in this review paper, which describes physicochemical conditions required for the presence of geofluids, their compositions, and related tectonic setting and geodynamic phenomena. On the basis of the maximum water content that can be stored in crust-mantle rocks, subduction zone processes are discussed in which slab-derived fluids that are enriched in solid components play important roles: viscosity-flowthermal field and melting in the mantle wedge, and origin of deep-seated fluid such as Arimatype brine. The fluid flux in the arc crust may be captured by geophysical and geochemical observations, such as seismicity, seismic velocity, electrical conductivity, and helium isotopic ratios. Several specific phenomena such as migrating seismic events and localized crustal deformation may be attributed to such fluid fluxes from the depths, which have been induced by an elevated fluid pressure and a reduction of rock strength and viscosity.