RARE-EARTH ELEMENT GEOCHEMISTRY OF THE JORDANIAN UPPER CRETACEOUS PHOSPHORITES

A total of thirty-five samples of the economic grade Jordanian Upper C retaceous phosphorites were analysed for certain major and rare earth elements (REE) with an overall objective of understanding phosphogenes is conditions. These samples represent pelletal (granular) phosphorite s with traces of carbonates and marl. The deposits are of shallow subt idal environment of authigenic nature. The relative abundance of REE n ormalised to shale standard is indicative of proximal to onshore phosp horites. The distribution patterns of the REE show a depletion in ceri um (Ce) and light REE (LREE) and enrichment in the heavy REE (HREE), i ndicating marine depositional environment. The highly negative Ce anom alies of these samples indicate phosphogensis under oxic marine condit ion which are interpreted as a signature of deep cold upwelling seawat er on shallow epeiric shelf, cleanliness of these deposits from clay m inerals and to the very limited diagenetic processes affecting them af ter deposition.