Water -rock interaction induced by fracturing within fault zones

本研究的目的是：（1）建立具体的实验方法，以探索不同化学环境下岩石表面与水之间的自由基反应;（2）了解它们的基本机理。在此基础上，本文对该领域的研究进展进行了综述。(1)A.压裂试验机由“振动式”改为“旋转式”。新的旋转式装置的压裂效率约为旧型的10倍。B。通过引入气体交换系统，可严格控制气体气氛。在样品处理过程中实现了纯氩气气氛。C.“通过使用铝陶瓷对振动型装置进行了重新建模，使其能够进行更高温度的实验。(2)这些实验系统的扩展使得能够阐明以下事实。A.对于石英，氢气的产生量与通过压裂新产生的表面积完全成比例。钾长石、黑云母和白云母也证实了类似的关系。B。氢离子的量也与石英产生的表面积成比例。然而，对于钾长石和其他片状硅酸盐矿物，由于碱金属离子从矿物释放到流体中，流体通过压裂而变成碱性。C.离子强度控制的实验澄清了在较低pH值的流体中产生的氢气量较少。D.断裂带周围的天然流体表明，在破坏带中观察到氢气浓度，而在断裂的核心区中的氢气浓度与背景水平相似。这些研究结果使我们能够研究断裂带中的天然流体与压裂之间的关系。

This research has been conducted in order (1) to establish concrete experimental methods to explore the free radical reaction between fractured-rock surface and water under various chemical environments, and (2) to understand fundamental mechanisms of them. In these viewpoints, the progress of research is as follows.(1) A. Experimental machines for fracturing have been modified from "Shaking-type" to "Rotary type". The new rotary type apparatus has an efficiency of fracturing around 10 times compared to old type. B. Gas atmosphere could be strictly controlled by introducing gas-exchange system. Pure argon atmosphere was realized during treatment of samples. C. "Shaking-type apparatus was re-modeled by using alminum-ceramics which enables to perform higher temperature experiments.(2) These extension of experimental system enables to clarify following facts. A. For Quartz, amounts of generation of hydrogen gas was completely proportional to the newly created surface area by fracturing. Similar relationships were confirmed for K-feldspar, biotite and muscovite. B. Amounts of hydrogen ions are also proportional to the created surface area for quartz. However, for K-feldspar and other sheet silicate minerals, fluids become alkaline by fracturing due to release of alkali metal ions from minerals to fluids. C. Ionic strength-controlled experiments clarified that less amounts of hydrogen gas was generated in lower pH fluids. D. Natural fluids around the fault zone show concentration of hydrogen gas was observed in damaged zone, whereas those in core zone of the fault are similar to background level. These results of research enable us to examine the relationship between natural fluids in the fault zone and fracturing.