RARE EARTH ELEMENT GEOCHEMISTRY OF SURFACE SEDIMENTS IN MID-BENGAL BAY AND IMPLICATIONS FOR PROVENANCE

Rare earth elements (REEs) of 110 surface samples taken from the mid-Bengal Bay have been analyzed for provenance studies. The total REEs vary in a range from 93.90×10^-6~220.80×10^-6, with an average of 138.25×10^-6, which is close to the Upper Continent Crust. The samples are relatively enriched in LREEs, with flat HREEs patterns and moderate negative Eu anomalies.No apparent Ce anomalies have been found. Enrichment factor, discrimination function and ∑REE-(La/Yb)_N scatter diagram ascertain that the provenances are dominated by Himalaya and the Tibetan plateau with minor contributions from the India continent, but no apparent materials from Irrawaddy. Cluster analysis of REE parameters after Gangs-Brahmaputra (G-B) normalization implies that the main influence area of Indian provenance is in the west of the study area controlled by sediments supply and transport dynamics of the surface circulation system in the Bay of Bengal, especially the East India Coastal Current (EICC).