Earth:Comminution dating
Comminution dating is a developing radiometric dating technique based on the disequilibrium between uranium isotopes in fine-grained sediments.[1]
Theory
An alpha-particle with a finite energy is emitted during the alpha decay of uranium-238 to uranium-234 via the short-lived thorium-234. In order to conserve momentum, the daughter nuclide, uranium-234, is recoiled. In silicate mineral grains with high surface-area-to-volume ratios, a certain fraction of nuclides may be directly ejected into the surrounding medium (water or air).
Applications
Comminution dating has been applied to dating of:
Developments
In order to calculate reliable comminution ages, authigenic uranium must be removed from the surface and pores of silicate minerals.[5] used an etching procedure to evaluate the completeness of existing sample pre-treatment procedures. It was found that further chemical pre-treatment steps are required to completely remove authigenic uranium from sediments. Further work is required to test this approach of samples from different depositional environments.
References
- ↑ DePaolo, D.J., Maher, K., Christensen, J.N. and McManus, J., 2006. Sediment transport time measured with U-series isotopes: results from ODP North Atlantic drift site 984. Earth and Planetary Science Letters, 248(1), pp.394-410.
- ↑ Aciego, S., Bourdon, B., Schwander, J., Baur, H. and Forieri, A., 2011. Toward a radiometric ice clock: uranium ages of the Dome C ice core. Quaternary Science Reviews, 30(19), pp.2389-2397.
- ↑ Dosseto, A., Hesse, P.P., Maher, K., Fryirs, K. and Turner, S., 2010. Climatic and vegetation control on sediment dynamics during the last glacial cycle. Geology, 38(5), pp.395-398.
- ↑ Lee, V.E., DePaolo, D.J. and Christensen, J.N., 2010. Uranium-series comminution ages of continental sediments: Case study of a Pleistocene alluvial fan. Earth and Planetary Science Letters, 296(3), pp.244-254.
- ↑ Martin, A.N., Dosseto, A. and Kinsley, L.P., 2015. Evaluating the removal of non-detrital matter from soils and sediment using uranium isotopes. Chemical Geology, 396, pp.124-133.
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