岡山県南部の風化花崗岩中の粘土鉱物 : その1:笠岡市北木島について

概要

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The constituent clay minerals of the weathered granites (saprolite), veins, and fractures in the Sanyo-type granitic body, and the vein in the Ryoke-type granitic body of Kitagi Island, Okayama Prefecture, have been examined by X-ray powder diffraction. The saprolite contains halloysite, vermiculite, and a small amount of kaolinite. The clay vein mainly consists of halloysite and a small amount of kaolinite, vermiculite, and di-octahedral smectite in the Sanyo-type granite, and kaolinite and vermiculite in the Ryoke-type granite. In the fracture, commonest clay mineral is di-octahedral smectite with subordinate amounts of halloysite and kaolinite. Mica clay mineral is found in all cases. The clay minerals in the saprolite were formed during the chemical weathering. On the other hand, it seems that the clay minerals in the veins and fractures are hydrothermal origin and remain unchanged through weathering.
岡山理科大学の論文