『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