Rare earth element (REE) geochemistry of phosphorites of the Sonrai area of Paleoproterozoic Bijawar basin, Uttar Pradesh, India

The rare earth element (REE) data from the Paleoproterozoic Bijawar basin, Sonrai phosphorites were used to interpret the depositional conditions of the phosphorites. The post archean Australian shales (PAAS) normalized REE patterns of the Sonrai phosphorites were characterized by negative Ce and positive Eu anomalies. Middle rare earth elements (MREE)-enrichment was a characteristic feature. Phosphorites showing the diagenetic effects on the REE patterns were limited. The observed Eu anomaly was indicative of an anoxic (or sulphate reducing) diagenetic environment of phosphate formation. Mixing of sea water and upwelling during the Paleoproterozoic was responsible for the recording of positive Eu and negative Ce anomalies in the Sonrai phosphorites.