Geochemistry of Brown Detrital Limestone BedswWithin Sarmord Formation, Sulaimani, Kurdistan Region, Iraq: Implication for Depositional Environment, Provenance and Tectonic Setting

Abstract

Fifteen samples of brown detrital limestone beds within the Sarmord Formation from the Imbricated Zone (Qaiwan and Barzinjah sections) and High Folded Zone (Zewe section), Kurdistan region, NE-Iraq were analyzed. The analysis includes the major oxides, trace elements, and rare earth elements (REEs) to find out their provenance, tectonic setting, and depositional environment. These beds are mainly composed of detrital limestone in which calcite and traces of quartz are confirmed by XRD and the microscopic study. Al2O3/TiO2, La/Sc, La/Co, Th/Sc, Cr/Th and Th/Cr ratios and {(TiO2 + V2O3) - (MgO/ (MgO + Al2O3)}, (TiO2 - Ni), (La/Th - Hf), (La/Sc - Co/Th) diagrams reveal sourcing from the mixed carbonate platform and felsic rocks. The ratios of major, trace, and REE with PAAS values fall within the range of felsic rocks, which agree with Cretaceous western Iraq (present Western Desert) as a source of these beds. The (Rb – Sr – Ba) ternary diagram and (Sr/Ba-Sr/Rb) diagram display the distribution of the samples between the continental margin and inland field. Tectonically, these detrital limestones are transported from the erosion of the interior of the Arabian platform into deep marine and interbedded with the green marl. The V/Cr, U/Th, Ni/Co, and Sr/Ca ratios and diagram of Al2O3-V indicate deposition under shallow marine oxic to the dysoxic environment and transported to the deep marine. The paleoclimate index C-value, Sr/Cu ratio, and SiO2 - (Al2O3 + K2O + Na2O) diagram indicates hot arid conditions. Paleosalinity ratios Rb/K and Sr/Ba imply brackish to marine water conditions.