REE and U mineralization in the phosphorites of the Pabdeh Formation, Sheikh Habil area, Kohgiloyeh-Boyer Ahmad province, SW of Iran

Sheikh Habil area is located in 80km of Dehdasht city in southeast of Kohgiloyeh-Boyer Ahmad province, SW of Iran. Pabdeh Formation is located in the Zagros structural zone of Iran. The host rocks of the area are the Late Paleocene-Early Oligocene limestones, shales and marls. Calcite, fluorapatite, glauconite, quartz and clay minerals are the most observable minerals in these phosphorite rocks. The geochemical data show that the average contents of P2O5, U and ΣREE are 24.47%, 100ppm (with enrichment factor of 46.54) and 189.18 ppm, respectively. The (La/Yb)N is 0.62-0.54 and the (LREE/HREE)N is 0.62-0.72. The studied samples have negative Ce anomaly which indicates the existence of an anoxic environment during the Sheikh Habil phosphate deposition. These ratios show the relatively enrichment in HREEs with respect of LREEs. This data confirms that the Sheikh Habil phosphorites have high anomalies not only for P2O5 but also for U and HREEs. These data show that the other areas in Pabdeh Formation could be good targets for P2O5, U and REEs.