Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/92990
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- Title
- The Relationship between riverine U-series disequilibria and erosion rates in a basaltic terrain
- Related
- Earth and planetary science letters, Vol. 249, No. 3-4 (2006), p.258-273
- DOI
- 10.1016/j.epsl.2006.07.001
- Publisher
- Elsevier
- Date
- 2006
- FoR/RFCD Code(s)
-
040300 Geology
040600 Physical Geography and Environmental Geoscience
- Author/Creator
- Vigier, N
- Author/Creator
- Burton, K. W
- Author/Creator
- Gislason, S. R
- Author/Creator
- Rogers, N. W
- Author/Creator
- Duchene, S
- Author/Creator
- Thomas, L
- Author/Creator
- Hodge, E
- Author/Creator
- Schaefer, B
- Description
- U-series isotopes have been measured in the dissolved phase, suspended load and bedload of the main rivers draining basaltic catchments in Iceland. For the dissolved phase, (234U/238U) and (238U/230Th) range between 1.08 and 2.2, and 7.4 and 516, respectively. For the suspended load and bedload, (234U/238U) and (238U/230Th) range from 0.97 to 1.09 and from 0.93 to 1.05, respectively. Chemical erosion rates, calculated from dissolved major elements, range between 13 and 333 t km− 2 yr− 1. Physical erosion rates have also been estimated, from existing data, and range between 21 and 4864 t/km2/yr, with an average of 519 t km− 2 yr− 1. U-series disequilibria indicate that weathering in Iceland operates at close to steady-state conditions. A model of continuous weathering indicates a maximum weathering timescale of 10 kyr, with an average rate of uranium release into water of 1.6 · 10− 4 yr− 1, which is significant when compared to granitic terrains located at similar latitudes and to tropical basaltic terrains. All river waters display (234U/238U) greater than secular equilibrium, consistent with the effects of alpha-recoil. The same dissolved phase (234U/238U) exhibit a negative trend with physical erosion rates, explained by the dominant effect of close-to-congruent chemical weathering of hyaloclastites in the younger basaltic terrains. Therefore, chemical erosion rate and mineral weathering susceptibility play a major role in determining 234U–238U disequilibria in basaltic river waters. Comparison of global data for river basins in which weathering was recently strongly limited indicates a negative correlation between silicate weathering rates estimated with major elements and the age of weathering estimated with U-series disequilibria. This strongly suggests a key role of time and soil thickness on the chemical erosion of silicates.
- Description
- 16 page(s)
- Subject Keyword
- 040300 Geology
- Subject Keyword
- 040600 Physical Geography and Environmental Geoscience
- Subject Keyword
- U-series disequilibria
- Subject Keyword
- Iceland
- Subject Keyword
- erosion
- Subject Keyword
- weathering timescale
- Subject Keyword
- steady-state
- Subject Keyword
- basalt
- Resource Type
- journal article
- Organisation
- Macquarie University. National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC)
- Identifier
- http://hdl.handle.net/1959.14/92990
- Identifier
- ISSN:0012-821X
- Identifier
- mq-rm-2009007168
- Language
- eng
- Reviewed
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