Mineralogy and Geochemistry of Qulqula Limestone in Shenrui, Halabja Governorate, Northeastern Iraq

Abstract

This study focuses on the mineralogy and geochemistry of the limestone unit of the Qulqula Formation (Early Cretaceous). The age and stratigraphic position of this formation are controversial because of insufficient studies and the complex structure of the occurrence area. Twenty samples were selected and analyzed which represent six sections: Sarkan, Awera, Griana1, Griana2, Hawar, and Hawara Kon at the Mount of Shenrui in Halabja area located in Kurdistan Region, northeastern Iraq near the IraqiIranian borders. The mineralogical study by the X-ray diffraction technique shows that the samples are composed of 70.14 % calcite, and 28.07% quartz. The geochemical analysis shows that CaO is abundant in most of the studied samples, the increases of (SiO2, Al2O3, Fe2O3, TiO2, and K2O), and the decrease in (CaO and MgO) leads to the change of limestone to siliceous type. The limited dolomitization can be confirmed by the low concentration. The component Sr has a negative correlation for both major and trace elements. On the other hand, (Cr, Co, Ni, V, and Zr) have a positive correlation with (MgO, Fe2O3, SiO2, Al2O3, K2O, and TiO2), this may indicate the effect of the basic rocks in surrounding areas enriching limestone with these elements.