Geochemical Criteria for Discriminating Shallow and Deep Environments in Oligocene-Miocene Succession, Western Iraq

Abstract

The geochemical study of the Oligocene-Miocene succession Anah, Euphrates, and Fatha formations, in western Iraq, was carried out to discriminate their depositional environments. Different major and trace patterns were observed between these formations. The major elements (Ca, Mg, Fe, Mn, K, and Na) and trace elements (Li, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Cs, Ba, Hf, W, Pb, Th, and U) are a function of the setting of the depositional environments. The reefal facies have lower concentrations of MgO, Li, Cr, Co, Ni, Ga, Rb, Zr, and Ba than marine and lagoonal facies but have higher concentrations of CaO, V, and Sr than it. Whereas dolomitic limestone facies are enriched V, and U while depletion in Li, Cr, Ni, Ga, Rb, Sr, Zr, Ba, and Pb Conversely, the lagoonal facies are rich in clay minerals and associated trace elements Li, V, Cr, Co, Ni, Cu, Ga, Rb, Zr, Ba, and Pb.