7. Bioclastic wacke/grainstone
General Atlantic, Tjaden 1A1 WIW # 1, 4347 ft, showing a contact (at arrow head) between encrinitic grainstone (lower right) and autoclastic chert. Top of encrinite is solution microkarst. Solution cavities are deep, cutting through approximately 0.5 m of core. Contact is also boundary of cycle 2. Encrinite is tightly cemented by calcite stained here with alizarin-red. Scale is 2 cm. Photomicrograph below the rock slab from 4341 ft from encrinite capping the thin cycle 3. Alizarin-red stain helps to distinguish the slightly darker and cloudy crinoid ossicle from the syntaxial calcite overgrowth cement. Unstained patches of replacive microquartz with accompanying microporosity and vugs also shown. Blue epoxy also shows a small amount of interparticle porosity. Scale is 0.1 mm. Photographed in plane polarized light.