Figure F22. A. Photomicrograph of typical diagenetic features in sandstones from the middle of Unit II. The left-hand green grain possibly represents a devitrified glass shard made up of cryptocrystalline clay minerals. Together with the other framework grains, it is coated by clay rims. The pore-lining clay rims are overgrown by zeolite spherolites that occupy the intergranular pore space (thin section from Sample 195-1201D-14R-1, 9-11 cm [205.39 mbsf]) (slightly cross-polarized light). B. Photomicrograph of detail of pore-filling zeolite spherolites, displaying fan-shaped outlines in cross section. The roots likely consist of fibrous analcime, overgrown along a sharp contact by radiating prisms of clinoptilolite (thin section from Sample 195-1201D-17R-3, 106-108 cm [237.77 mbsf]) (plane-polarized light).

Figure F22. A. Photomicrograph of typical diagenetic features in sandstones from the middle of Unit II. The left-hand green grain possibly represents a devitrified glass shard made up of cryptocrystalline clay minerals. Together with the other framework grains, it is coated by clay rims. The pore-lining clay rims are overgrown by zeolite spherolites that occupy the intergranular pore space (thin section from Sample 195-1201D-14R-1, 9-11 cm [205.39 mbsf]) (slightly cross-polarized light). B. Photomicrograph of detail of pore-filling zeolite spherolites, displaying fan-shaped outlines in cross section. The roots likely consist of fibrous analcime, overgrown along a sharp contact by radiating prisms of clinoptilolite (thin section from Sample 195-1201D-17R-3, 106-108 cm [237.77 mbsf]) (plane-polarized light).