火成岩の風化に關する研究 : (第16報)安山岩の風化 (3)

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概要

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• (1) The author has studied on the weathering of biotite hornblende andesite found at Oh-ata-mura, Saihaku-gun, Tottori Prefecture. The fresh. rock, weathered rock, and light brown soil (B2 horizon) were used as material for the investigation. (Annual mean temperature…… 13.6°, annual rainfall…… 2200mm). (2) With the progress of the weathering, NIGGLIs values si, c, alk, and si/al decreased, . while al and h increased, k, m/c, f, and m slightly increased. In the weathering of this rock, the hornblende was not decomposed, however the plagioclase and the ground mass were decom-posed more rapidly than those in the pyroxene andesite previously reported. Al, Ca, and Mg in the rock partly remained in the undecomposed hornblende. (3) The light brown soil contained a small amount of free alumina (about 1%). In the weathered rock and soil, a large portion of the iron soluble in HCl was existent in the form of free iron oxide consisting of both limonitic (L) and hematitic oxide (H), and the ratio, of H/(H+L) increased in upper horizons. (4) The formation of weathering complex A1 and A2 from this rock began at an earlier stage of the weathering process. The complex A1 was allophane-like substance, and the complex A2 halloysitic, The kaolinite formation took place at a later stage of the weathering. The soil from this rock was rich in allitic allophane-like substance. On the contrary, the soils from the other igneous rocks in the same district were poor in allophane-like substance, and were siallitic. These facts show that the soil formation from the biotite hornblende andesite studied was highly influenced by the intrinsic factor. This character is important for classifying this soil. (5) In the light brown soil, the amount of exchangeable bases was very small, and the hydrolytic acidity was very high, though the exchange acidity was not so high, and the hydrolytic acidity was 32.4 times as great as the exchange acidity. (6) The clay separated from this andesite soil contained both allophane-like substance and halloysite.

• 社団法人 日本農芸化学会の論文

著者

• 原田 光

  鳥取大学学芸学部

関連論文

• 第三紀堆積岩の風化に関する研究(第2報) : 津山盆地の第三紀層土壌について(2)
• 第三紀堆積岩の風化に関する研究 第1報 : 津山盆地の第三紀層土壌に就いて(1)
• 鳥取県若桜町に於ける蛇紋岩の風化に就いて
• 土壌及び植物灰の放射能について(秋季大会第二会場)
• 火成岩の風化に關する研究 : (第17報)鳥取地方の火山性土壌について (1)
• 火成岩の風化の関する研究 : (第18報)鳥取地方の火山性土壤について (2)
• 火成岩の風化に關する研究 : (第16報)安山岩の風化 (3)
• 火成岩の風化に關する研究 : (第15報)安山岩の風化 (2)

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