REE and trace elements U and Th from the manganese-bearing rock series in the Middle Triassic Falang Formation in southeastern Yunnan

The REE compositions are explored by using ICP-MS method for 17 pieces of manganese ore samples and 2 pieces of manganese-bearing limestone samples from the manganese-bearing rock series in the Middle Triassic Falang Formation in southeastern Yunnan. The REE distribution patterns for all these samples display the patterns for the enrichment in LREE. The manganese ore samples are characterized by slight Ce (δCe values ranging from 0.79 to 1.29) and Eu (δEu values ranging from 0.84 to 1.20) anomalies. The manganese-bearing limestone samples are characterized by highly negative Ce anomalies and slightly negative Eu anomalies. It is concluded that the manganese-bearing rock series in the Middle Triassic Falang Formation in southeastern Yunnan are commonly subjected to hydrothermal processes and resulted from polyphase processes.