Distribution of rare earth elements in Early Permian reef-island ocean sediments in eastern Kunlun

Based on the study of stratigraphy and fossils, the Early Permian ocean in eastern Kunlun is recognized as a kind of reef-island ocean, in which there exist many different kinds of sediment, including patch carbonate platform , reef facies, transitional facies and deep basin sediments. It has been fo und that the total contents of REEs increase gradually from carbonate platf orm facies to deep basin facies. Meanwhile, sediments of different facies h ave different REE distribution patterns and different Cc anomalies. Most of the sediments of patch carbonate platform facies or reef facies are charac terized by extremely negative Ce anomalies or moderately negative Ce anomal ies (Ce/Ce*=0.33 to 0.55), and medium or thin-bedded limestones of transiti onal facies by moderately negative Cc anomalies (Ce/Ce*=0.49 to 0.60). Howe ver, sediments of deep basin facies show weak or no negative Cc anomalies ( Ce/Ce*=0.69 to 1.47), among which the value of Ce/Ce* in the radiolarian ch ert is 1.47.