Chen, Tian-Yu, Li, Gaojun, Frank, Martin and Ling, Hong-Fei (2013) Hafnium isotope fractionation during continental weathering: Implications for the generation of the seawater Nd-Hf isotope relationships. Geophysical Research Letters, 40 (5). pp. 916-920. DOI 10.1002/grl.50217.

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Abstract

To investigate the mechanisms of the offset of seawater radiogenic Nd-Hf isotope compositions from those of the upper continental crust rocks, combined Nd-Hf isotope compositions
of desert and loess samples from northern China (which integrate a wide range of lithologies and ages of continental rocks) are presented in this study. The results show significant and systematic fractionation of Hf isotopes between finegrained detritals/leachates (<5 mm) and coarser fractions (<75 mm) of the same samples. A small but systematic difference of Nd isotope compositions between leachates and detrital silicates is also revealed. Overall, the leaching data either plot along or slightly above the Nd-Hf seawater array, providing strong direct support that the seawater Nd-Hf isotope relationship is predominantly generated by weathering of upper continental crust. Our study supports the application of dissolved Hf
isotopes as a proxy for different modes of weathering regimes rather than for continental source provenances.

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