Tracing rare earth elements distribution and enrichment mechanism in phosphorites of the Paleoproterozoic Bijawar Group in Mardeora Mine, Chattarpur district, Madhya Pradesh (M.P.), India

This study investigates the distribution and enrichment patterns of the rare earth elements (REEs) in phosphorites from the Hirapur Formation of the Paleoproterozoic Bijawar Group in the Mardeora area, Madhya Pradesh, India. The geochemical analysis of phosphorite samples reveals that the total REE concentrations ranging from 34.71 to 215.65 ppm (mean: 99.13 ppm), with middle rare earth element (MREE) exhibiting significant enrichment over light rare earth element (LREE) and heavy rare earth element (HREE) having (MREE/LREE) N and (MREE/HREE) N ratios averaging 6.39 and 3.11, respectively. The PAAS-normalized REE patterns are characterized by MREE enrichment and minor negative or no Ce/Ce* anomalies (Ce/Ce*: 0.80–1.01). Positive Eu/Eu* anomalies (1.06–1.52) and Y/Y* variations (0.47–1.67) are linked to suboxic pore-water conditions during late-stage diagenetic processes and the significant influence of detrital input (Y/Ho ∼ 28.78). Geochemical proxies, including La/Nd, Y/Y*, La/Yb, and La/Sm ratios, indicate limited weathering influence and diagenetic alteration, with REE enrichment primarily driven by substitution and recrystallization during late diagenesis. The studied phosphorites, despite having a low to moderate ΣREE concentration, can be categorized as promising, with a tendency towards being a highly promising critical REE resource.