Figure F13. Microflaser and anastomosing seams in limestone of Subunit IIB (Paleocene; interval 192-1183A-38R-1, 23-37 cm). The 1-cm-thick dark layer at 29-30 cm contains a concentration of zeolite and is streaked with light gray chalk. Outward from this layer is a progression from flaser-nodular chalk to thin anastomosing seams. These textures are probably produced under pressure-solution lithification of an altered volcanic ash bed that had been mixed with surrounding calcareous sediment by bioturbation. Such intervals are characteristic of Subunit IIB.

Figure F13. Microflaser and anastomosing seams in limestone of Subunit IIB (Paleocene; interval 192-1183A-38R-1, 23-37 cm). The 1-cm-thick dark layer at 29-30 cm contains a concentration of zeolite and is streaked with light gray chalk. Outward from this layer is a progression from flaser-nodular chalk to thin anastomosing seams. These textures are probably produced under pressure-solution lithification of an altered volcanic ash bed that had been mixed with surrounding calcareous sediment by bioturbation. Such intervals are characteristic of Subunit IIB.