Rare Earth Element Geochemistry of the Jordanian Upper Cretaceous Phosphorites PDF

Keywords

Upper Cretaceous, phosphorites, Jordan

Abstract

A total of thirty-five samples of the economic grade Jordanian Upper Cretaceous phosphorites were analysed for certain major and rare earth elements (REE) with an overall objective of understanding phosphogenesis conditions. These samples represent pelletal (granular) phosphorites with traces of carbonates and marl. The deposits are of shallow subtidal environment of authigenic nature. The relative abundance of REE normalised to shale standard is indicative of proximal to onshore phosphorites. The distribution patterns of the REE show a depletion in cerium (Ce) and light REE (LREE) and enrichment in the heavy REE (HREE), indicating marine depositional environment. The highly negative Ce anomalies of these samples indicate phosphogenesis under oxic marine condition which are interpreted as a signature of deep cold upwelling seawater on shallow epeiric shelf, cleanliness of these deposits from clay minerals and to the very limited diagenetic processes affecting them after deposition