Lee,B., Ha,Y., Huh,Y., Lundstrom,C., Siame,L.L., Lee,J.I., Park,B.-K. and ASTER Team(2013): Chemical and physical weathering in south Patagonian rivers: A combined Sr-U-Be isotope approach. Geochimica et Cosmochimica Acta, 101, 173-190.

『南部パタゴニアの河川における化学風化と物理風化:Sr-U-Be同位体を組み合わせたアプローチ』


Abstract
 We investigated physical and chemical weathering in south Patagonia, encompassing both the tectonically active Andes with alpine glaciers and the quiescent seaboard plain with arid climate. Chemical denudation rates determined from riverine dissolved major elements were (0.07-5)×105 tons year-1, and the long-term rates of CO2 consumption by alkaline earth silicates were (0.03-0.5)×105 mol km-2 year-1, commensurate with the average global CO2 consumption rate (0.25×105 mol km-2 year-1). Unradiogenic strontium isotope ratios indicated that the source of silicate weathering was volcanic sedimentary cover. Basin average total denudation rates based on 10Be measured in active streambed sediments ranged from 0.009 to -.6 mm year-1. Uranium series disequilibria suggested that there is significant redistribution of nuclides between the dissolved and suspended material. When applying the simultaneous gain and loss model to the U-series data of the suspended load, sediment residence times of 10-150 ky were obtained. Comparison of the dissolved load-based chemical denudation rate and 10Be-based total denudation rate revealed that some basins are dominated by chemical and some by physical denudation.』

1. Introduction
2. Geology and climate of the study area
3. Field and analytical methods
4. Results and discussion
 4.1. Chemical description
 4.2. Forward model
 4.3. Atmospheric CO2 uptake by silicate denudation
 4.4. Uranium-series disequilibria
 4.5. Inter-method comparison of the rates
5. Conclusion
Acknowledgements
Appendix
References


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