2003 Fiscal Year Final Research Report Summary
Water -rock interaction induced by fracturing within fault zones
| Project/Area Number |
13440134
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体地球物理学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TANAKA Hidemi The University of Tokyo, Graduate School of Science, Lecturer, 大学院・理学系研究科, 講師 (40236625)
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| Project Period (FY) |
2001 – 2003
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| Keywords | Water -rock interaction / Free radical reaction / BET surface area analysis / pH / Minerals / Fracturing experiments |
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| Research Abstract |
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.
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