著者

吉岡 龍馬

出版者

公益社団法人 日本地下水学会

雑誌

日本地下水学会会誌 (ISSN:00290602)

巻号頁・発行日

vol.26, no.4, pp.147-166, 1984-11-30 (Released:2012-12-11)

参考文献数

28

被引用文献数

3

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From the engineering geological, hydrogeological and geochemical points of view, the characteristics of water quality in groundwater (partly stream water) from the Rokko mountain area is summarized as follows; 1) water quality in groundwater 'through Nunobiki granodiorite shows Ca- Na-HCO3 type, and Na-HCO3 type is greater than Ca-HCO3 type in groundwater from Rokko granite, 2) the groundwater is characte-rized by higher alkalinity, higher pH and being rich in fluoride content than the stream water, 3) mineral and common water exist irregularly and alternatively within fault-sheared zone, 4) chondrite-normalized REE pattern in groundwater is regarded as an in-dex of water-rock interaction in deep underground, 5) from measurements of tritium, the turnover time of groundwater in a fractured system is about 40 years and the mean velocity of downward displacement flow about 10 to 17m/y, 6) some amount of stream water is supplied into groundwater contained in fractures or faults in base rock which. are crossing a stream, usually in a certain small amount, but during heavy rains dis- charge of supplied water increases suddenly to a great extent, and 7) a crustal deforma-tion occurs at or around the Rokko mountain area, increasing the underground supply of carbon dioxide gas and leading to very active water-rock interaction.

著者

高松 信樹 下平 京子 今橋 正征 吉岡 龍馬

出版者

一般社団法人日本地球化学会

雑誌

地球化学 (ISSN:03864073)

巻号頁・発行日

vol.14, no.2, pp.69-76, 1981-03-30 (Released:2016-11-17)

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Powdered granitic rocks were allowed to react with distilled water under various conditions to estimate the formation mechanism of natural waters from granitic area and to discuss on the factors influencing the chemical composition of the waters. The experimental results indicate that the chemical composition and pH of the waters are influenced by the kind of granitic rocks, the water/rock ratio and PCO2. The alkaline ground waters may result from the reactions of granitic rocks with the waters having low PCO2. The ground waters from granitic areas where CO2 from underground occurs abundantly are neutral or weak acidic, and their major species are Na+, Ca2+, HCO3-. The proportion of the components is nearly equal to that of the surface waters. The percolation time of ground waters in granitic areas was inferred to be relatively short because of the high permeability of water into granitic rocks and low content of dissolved species. Accordingly, the metastable alminosilicates produced during the incongruent dissolution of granitic rocks, may control the chemical composition and pH of the ground waters.