The relationship between riverine U-series disequilibria and erosion rates in a basaltic terrain

摘要: U-series isotopes have been measured in the dissolved phase, suspended load and bedload of main rivers draining basaltic catchments Iceland. For (234U/238U) (238U/230Th) range between 1.08 2.2, 7.4 516, respectively. bedload, from 0.97 to 1.09 0.93 1.05, Chemical erosion rates, calculated major elements, 13 333 t km− 2 yr− 1. Physical rates also estimated, existing data, 21 4864 t/km2/yr, with an average 519 disequilibria indicate that weathering Iceland operates at close steady-state conditions. A model continuous indicates a maximum timescale 10 kyr, rate uranium release into water 1.6 · 10− 4 1, which is significant when compared granitic terrains located similar latitudes tropical terrains. All river waters display greater than secular equilibrium, consistent effects alpha-recoil. The same phase exhibit negative trend physical explained by dominant effect close-to-congruent chemical hyaloclastites younger Therefore, mineral susceptibility play role determining 234U–238U waters. Comparison global data for basins was recently strongly limited correlation silicate estimated elements age disequilibria. This suggests key time soil thickness on silicates.