Constraining Rates of Chemical and Physical Erosion Using U-Series Radionuclides

Nathalie Vigier (1, 2, 3) , Bernard Bourdon

1 LOV - Laboratoire d'océanographie de Villefranche
2 CNRS - Centre National de la Recherche Scientifique
3 SU - Sorbonne Université

This chapter relates recent developments concerning the use of several U-series nuclides, in particular 234 U-238 U and 230 Th-238 U disequilibria, for constraining physical and chemical erosion rates and sediment age. Indeed, the ability to measure these disequilibria with an extremely high precision, even in samples with low concentrations such as natural waters, has opened new avenues for investigating erosional processes. This chapter is articulated in three main parts: a brief introduction and presentation of modern technical methods is followed by a description of how 234 U-238 U and 230 Th-238 U disequilibria measured in dissolved (water) and solid (sediment) river phases can be used to provide quantitative constraints on physical and chemical erosion rates at the basin scale. In parallel, recoil effects occurring during sediment formation can now be modelled and used to estimate the residence time of a sediment within a basin. Finally, the last part of this chapter presents the latest findings concerning the study of weathering profiles and the modelling of U and Th migration within an aquifer system.

Domaines: Planète et Univers [physics]

Nathalie Vigier, Bernard Bourdon. Constraining Rates of Chemical and Physical Erosion Using U-Series Radionuclides. Advances in Isotope Geochemistry, 2011, pp.553 - 571. ⟨10.1007/978-3-642-10637-8_27⟩. ⟨hal-03130852⟩