The significance of silica precipitation on the formation of the permeable-impermeable boundary within Earth's crust
The significance of silica precipitation on the formation of the permeable-impermeable boundary within Earth's crust
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DOI：
10.1111/ter.12093
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发表时间：
2014-08-01
期刊：
影响因子：
2.4
通讯作者：
Tsuchiya, Noriyoshi
中科院分区：
文献类型：
--
作者：
Saishu, Hanae;Okamoto, Atsushi;Tsuchiya, Noriyoshi
地壳内的水文系统分为渗透区和底层的渗透性低得多的区域。在这项研究中，我们研究了二氧化硅在水中的溶解度和沉淀动力学的条件下的Kakkonda地热田，日本，其中WD-1a穿透热液对流区和热传导区之间的边界。我们发现，石英溶解度有一个局部最小值的水文边界的深度，在类似于3100米的深度（380摄氏度和24 MPa），在流体静力学条件或流体压力增加以上的情况下，在更深的水平。水热实验表明，当流体从液相区带到超临界区时，通过成核作用发生快速石英沉淀。石英在特定深度的优先沉淀对地壳中渗透-不渗透边界的形成和维持起着重要作用。
The hydrological system within Earth's crust is divided into the permeable zone and the underlying, much less permeable zone. In this study, we investigated the solubility and precipitation kinetics of silica in water under the conditions of the Kakkonda geothermal field, Japan, where well WD-1a penetrates the boundary between the hydrothermal convection zone and the heat conduction zone. We found that quartz solubility has a local minimum at the depth of the hydrological boundary, at similar to 3100-m depth (380 degrees C and 24 MPa), in the case of either hydrostatic conditions or fluid pressure increase above hydrostatic at deeper levels. The hydrothermal experiments reveal that rapid quartz precipitation occurs via nucleation when fluids are brought from the liquid region to the supercritical region. The preferential precipitation of quartz at a specific depth plays a significant role in forming and sustaining the permeable-impermeable boundary in the crust.