福岡県津屋崎付近の第三紀層中の沸石と粘土鉱物

抄録

Zeolites occur abundantly in the Tertiary sedimentary rocks distributed near Tsuyazaki, Fukuoka Prefecture. These zeolites and clay minerals associated with them were investigated mainly by x-ray diffraction.
The zeolites occurring in amygdales, veinlets and filling materials of conglomerate were identified as heulandite, stilbite and laumontite, and those replacing matrix and plagioclase grain in sandstone were heulandite and laumontite. Of the latter group, heulandite occurs throughout the whole stratigraphical horizon, but laumontite is recognized only in the lower horizon. This fact suggests that the sedimentary rocks have been suffered the alteration of heulandite-analcime subfacies of Seki (1968), and the degree of alteration is a little higher in the lower horizon.
Most of the clay minerals associated with zeolites are interstratified minerals of illite and montmorillonite and chlorite minerals. Kaolin mineral and celadonite are rarely found. The amounts of montmorillonite layers in the interstratified minerals of illite and montmorillonite are estimated by visual inspection to range from 40 to 90%. The chlorite minerals in the rocks in the upper horizon consist of Ib(β=90°) FeMg-chlorite and interstratified mineral of chlorite and saponite in contrast with those in the lower horizon being FeMg-chlorite only. The interstratified mineral of chlorite and saponite contains 30-50% saponite layers.