Geochemistry of recent sediments of the Kurheri basin, Son River, Madhya Pradesh, Central India: implications for source area weathering, sediment provenance, maturity, and sorting

The geochemical signatures of recent stream sediments in the study area revealed an old recycled sedimentary source and weak to moderate chemical weathering. The sediments exhibit a positive correlation of large ion lithophile elements (Ba, Sr, and Rb), transition trace elements (Co, Cr, Cu, Ni, Sc, and V), and REE with Al2O3 and associated immobile oxides, indicating affinity with phyllosilicate sedimentary rocks of Semri Group of Vindhyan basin. The La-Th-Sc and Th-Sc-Zr/10 ternary plots show mixed sediment sources of clays, silts, and sands. Positive correlations of LREE with Th, Zr, Al2O3, and TiO2 and negative correlations with Y and P2O5 suggests the cumulative influence of Ti-bearing minerals and clay minerals. The high Zr/Sc ratio (mean 30.8), strong LREE/HREE enrichment (mean 8.1), prominent negative Eu anomalies (mean 0.57) and flat HREE suggest input from the recycled sedimentary source. The mean chemical index of alteration (69.17), plagioclase index of alteration (74.94), chemical index of weathering (93.08), and ACNK indicate weak to moderate weathering with the presence of minor K-feldspar mixed in illite dominated mud. This is also supported by a high Rb/Sr ratio (mean 1.09) and K/Rb ratio (0.018). A higher K/Al than Na/Al ratio points to higher illite content. The presence of illite, minor feldspar, and less SiO2/Al2O3 ratio (mean 4.98) suggests low textural and compositional maturity, attributed to the mixing of sediments by significant physical weathering. The positive correlation between Th/Sc (mean 0.6) and Zr/Sc (30.8) indicates less fractionation, low to moderate hydraulic sorting, and sufficient sediment recycling in Kurheri sediments.