Geochemical characteristics of the trace elements and heavy metals in the sequences in Gachsaran Formation, West of Iran

Abstract

In the present study, the geochemical characteristics of sequences of the Gachsaran Formation, located in the west of Kermanshah province, Iran - Iraq border zones, were studied. In order to determine the concentration of the elements, the XRF and ICP-mass techniques were employed, and the XRD technique was used to identify the mineralogical composition and finally, the evaluation of the level of pollution caused by these elements were carried out using statistical and pollution index software.The results illuminated that the concentrations of CaO, MgO, TiO2, and concentrations of two elements, i.e., Cd and Sb were higher than their mean values in the earth’s crust. Based on the CF pollution index, the elements of Cd and Sb with the values of 1.52 and 2 show the moderate contamination. Enrichment factor (EF) revealed moderate contamination for Cs (2.46), Ga (3.86), Rb (2) and Ti (2.35). This index showed the high pollution and anthropogenic origin for Ti (8), Cd (10.41), U (11.26) and Sb (13.43). The results of the correlation between the elements indicated the presence of positive and significant correlation between Cs, Hf, La, Nb, Nd, Rb, Sc, Sm, Ta, Tb, Th, Tl, W, Y, Yb, and Zr. There was no positive and significant correlation between U and none of the elements. Three elements of Sb, U, and Cd showed a negative correlation with most of the studied elements. According to the results of cluster analysis, three separate groups were obtained so that each of Ti and Fe was classified as separate groups and Fe showed the highest difference in comparison with other elements. Based on the results of the Principal Component Analysis (PCA), the highest effect was related to the elements of Cs, Hf, La, Nb, Rb, Sc, Sm, Tb, Th, Tl, W, Y, Yb, Zr, Fe in the first Component, Sb, Cd in second component and U in the third component.