Origin of upper Cretaceous multicolored claystones of the western Atlantic.

Cores show that U.Cretaceous sediments directly overlying the black shale facies are generally 'red' or 'multicolored' clay. These non-calcareous U.Cenomanian to L.Maestrichtian (?) claystones, which contain no fossils, probably represent slow deposition under well-oxygenated-conditions and a high CCD. It is not necessary to assume a volcanogenic source for the metals and minerals assemblages within these multi-colored claystones. Diagenertic mobilisation of redox-sensitive metals within anoxic pore waters of the L.Cretaceous black shales and upward diffusion-advection into the oxidised claystones can account for the varible Fe-MN enrichment observed. -from Author