Geochemical signature of the Cenomanian to Eocene rocks in Israel -a palaeoenvironmental indicator

Distinctive trace-metal concentrations characterize Cenomanian to Eocene marine carbonates from Israel. The Cenomanian-Turonian platform carbonates, including clayey formations, exhibit low average values ranging between 2 and 29 ppm for Zn, Cr, V, Ni, Cu, U and Co. The Santonian-Campanian and Early to Middle Eocene marine chalks show higher average concentrations of these trace-metals ranging between 3 and 56 ppm. The highest average concentrations of these metals (5–118 ppm) are found in the Maastrichtian and in the Palaeocene marine chalks and marls. The possible relationship between these metal background levels and the lithology, the biogenic productivity, the organic matter content, the iron oxide concentration, the rate of sedimentation of the studied time-rock units as well as the palaeogeographical changes are discussed. The extent of the exposed palaeo-landmasses due to tectonics, the intensity of weathering conditions and the detritus supply into the basin, control primarily the iron and trace-metal content in the studied sediments.