Figure F20. Laminated dark calcareous claystone in Subunit IIIB (Aptian-Albian; interval 192-1183A-53R-4, 15-35 cm). Discrete laminae are composed of concentrated foraminifers or of fine-sand material. Claystone composition is dominated by iron oxyhydroxides (goethite) and nontronite with ~30% nannofossils and scattered planktonic foraminifers. The absence of bioturbation contrasts with adjacent beds of bioturbated limestone.

Figure F20. Laminated dark calcareous claystone in Subunit IIIB (Aptian-Albian; interval 192-1183A-53R-4, 15-35 cm). Discrete laminae are composed of concentrated foraminifers or of fine-sand material. Claystone composition is dominated by iron oxyhydroxides (goethite) and nontronite with ~30% nannofossils and scattered planktonic foraminifers. The absence of bioturbation contrasts with adjacent beds of bioturbated limestone.