Indian Ocean river inputs

Bertram and Elderfield (1993) point out the major features with respect to fractionation. As expected from their close positions in the lanthanide series, the oceanic distributions of Nd and Sm are tightly coupled. Sm and Nd molar ratios range between 0.181 and 0.203, with very minor variability and a mean value equal to 0.189. Sm/Nd ratios decrease in the following sequence Atlantic (0.203 0.009, mean and standard deviation) > Indian Ocean (0.196 0.013) > Pacific (0.181 0.024). Thus, the inter-basin differences are not significant relative to the range for each ocean. Since the Sm/Nd ratio for average shale is identical to the oceanic mean but is smaller than Sm/Nd for dissolved lanthanides (Sm/Nd w 0.25) in many rivers (Elderfield et al. 1990), oceans are fractionated relative to the dissolved river input with a small enrichment in Nd relative to Sm (Bertram and Elderfield 1993). 

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