Paleoenvironmental Conditions of the Chia Gara Formation from Rania Section Northeastern Iraq Using Geochemical Constraints

Abstract

The Chia Gara Formation at Rania section located in Shawli anticline near the village of Hangerah in the Rania district of Sulaymaniyah northern Iraq . This section consists mainly of limestone and shale containing organic matter. Geochemical data of major and trace elements were used in order to constrain paleoenvironmental conditions including paleoproductivity, redox conditions, hydrodynamic conditions, paleoclimate , paleo-water depth, hydrographic conditions and hydrothermal activity. The productivity proxies (Ba/Al and P/Ti ratios) indicate lower productivity. Redox proxies for trace elements [V/(V + Ni), V/Cr, Ni/Co, and Mo] suggest anoxic to dysoxic marine conditions. The Zr/Rb values indicate roughly that the hydrodynamic energy increased from lower to upper section. Sr/Cu and Rb/Sr ratios, which are paleoclimate proxies, indicate a semiarid to arid climatic conditions. The Co*Mn proxies refer to open marine environments associated with upwelling as well as subordinate restricted marine environments. Ni–Zn–Co plot suggests hydrothetrmal activity during deposition . The Rb/Zr ratio indicate shallowing upward during sedimentation