Mineralogical and geochemical features of Sirginil phyllite group from Penjween area,Iraqi Kurdistan region:Implications for provenance and source-area weatheringOA

The Sirginil Phyllite Group being outcropping in Penjween area is investigated to determine the provenance and weathering level of the source area.Petrographic investigation of the phyllites shows that they are almost homogeneous in composition and highly crenulated.The most prominent features are kink band structures and network fabrics,consisting mainly of fine-grained mineral assemblages of chlorite,muscovite,quartz,and plagioclase feldspar.The geochemical data indicate that the phyllite rocks represent precursors of shales and greywackes as their protolith,having undergone an intensive degree of chemical weathering without sorting.Additionally,the presence of graphite,as an indication of organic matter,points to quick transport and burial of the protolith sedimentary rocks,which originated from a unique source area.The average values of the chemical alteration index and chemical weathering index indicate that a high degree of weathering of the source materials occurred in a humid environment.The Th/U ratio,as well as the concentrations of Th and U,indicates a sedimentary origin and oxidizing conditions during sedimentation of the protolith rocks.The REE pattern coupled with prominent negative Eu anomaly and low Th/Sc ratios,as well as the plots of La/Sc versus Th/Sc,La/Yb versus La/Ce,and Th/Yb versus Ta/Yb,indicates a continental margin as the paleoenvironment of the sedimentary protolith.The Th/Sc ratios for the studied samples denote origin from a predominantly felsic igneous source,while the median Zr/Sc ratio indicates only a minor degree of sorting and zircon addition in all the studied samples.