Characteristics of rare earth elements in the sediment cores from the Okinawa Trough and their implications for sediment provenance

Multiple provenances are confirmed in the Okinawa Trough by a comparative study of the composition and fractionation of rare earth elements (REEs) in the sediment cores from southern, middle, and northern parts of the Trough. Distinctive differences in REEs compositions are discovered in different cores due to the different contribution of terrigenous detrital sediments from surrounding rivers and volcanic sources. The values of ∑REE and ∑LREE decrease from south to north, whereas ∑HREE values are relatively high in the north and followed by the south as the next. The fractionation degree between LREEs and HREEs, and the internal fractionation degrees of LREEs and HREEs decrease from south to north. The vertical variations in grain size, trace elements and REE characteristic parameters suggest that the sediment provenance of Core S3 was rather simple and the depositional environment was relatively stable. It is mainly controlled by terrigenous materials from the Yangtze River and Taiwan rivers. However, the sediment provenance of Core S10 and Core S9 are quite complicated, especially in the core of S9. Provenance changes remarkably with time. Layer 1 of Core S10 principally came from both the Yangtze River and Yellow River, while the Layer 2 has the mixed characteristics of volcanic materials and Yellow River sediments; The Layer 1 of Core S9 is the mixed deposits of volcanic materials and the Yellow River sediments, whereas the Layer 2 is mainly derived from the terrigenous particulate matters from the Yellow River.