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長野県稗田山崩壊地における安山岩の化学風化について(予報) (大木靖衛教授退官記念号)
長野県稗田山崩壊地における安山岩の化学風化について(予報) (大木靖衛教授退官記念号)
Chemical Weathering of andesitic rocks at the Hieda-yama landslide area, Nagano Prefecture.
相楽, 渉
渡部, 直喜
佐藤, 修
丸井, 英明
垣原, 康之
The Hieda-yama landslide area
landslide
debris flow
chemical weathering
soil production
稗田山
大崩壊地
土石流
化学風化作用
土砂生産
The Hieda-yama landslide area is located in the northwestern part of Nagano Prefecture. Landslides and debris flows have repeatedly occurred in this area. Bed-rock geology of this area is mainly composed of the Quaternary andesitic rocks. These andesites were weakly altered along joints and cracks in the rocks and are bearing secondary minerals such as pyrite, quartz and smectites. Ca and SO_4 ions of stream water are very concentrated in this landslide area. This fact suggests that the chemical weathering of andesitic materials is very active and the most important factor for occurrences of landslides and production of debris and soils. The chemical weathering in this area is dominated by the oxidation of pyrite, one of the secondary minerals by hydrothermal alteration. Rock forming minerals, particularly plagioclase are dissolved and their components are leached out by sulfuric acid formed by oxidation of pyrite. The annual rate of soil production by chemical weathering is estimated by using parameters such as average annual precipitation, catchment area, Ca concentration of stream water, density of soil and fresh andesite, and CaO content of fresh and weathered andesites.
新潟大学積雪地域災害研究センター
1998-03
jpn
departmental bulletin paper
http://hdl.handle.net/10191/39178
https://niigata-u.repo.nii.ac.jp/records/28042
AN00183327
03877892
新潟大学積雪地域災害研究センター研究年報
新潟大学積雪地域災害研究センター研究年報
19
83
96
https://niigata-u.repo.nii.ac.jp/record/28042/files/19_83-96.pdf
application/pdf
1.7 MB
2019-08-20