Calcrete is the widely prevalent duricrust associated with the weathering profiles of the Thar desert. The studies on REE behaviour within different weathering horizons of calcrete profiles, have revealed distinct pattern of enrichment and depletion. Fractionation of REE as evidenced through La/Lu, La/Sm, Nd/Dy ratios and removal index, are attributed to pedogenic processes such as breakdown of micas, pyroxenes, amphiboles, feldspars; removal of elements as soluble complexes; selective fixation of elements in neoformed clay minerals like montmorillonite, illite and chlorite. Sesquioxides rich Bir horizon shows enrichment of REE. REE depletion in Palaeo- Bt horizons could be due to their removal in solution as organic complexes.
RAMAKRISHNAN, D. and TIWARI, KRISHNA CHANDRA (1998) "Ree Chemistry of Arid Zone Calcrete Profiles-A Case Study From The Thar Desert, India," Turkish Journal of Earth Sciences: Vol. 7: No. 2, Article 5. Available at: https://journals.tubitak.gov.tr/earth/vol7/iss2/5