| Residual solid products of erosion display a wide range of size, density, shape, mineralogy, and chemical composition and are hydrodynamically sorted in large river channels during their transport. We characterize the chemical and isotopic variability of river sediments of the Amazon Basin, collected at different water depths, as a function of grain size. Absolute chemical concentrations and Sr and Nd isotopic ratios greatly varies along channel depth. The Al/Si ratio, tightly linked to grain size distribution, systematically decreases with depth, mostly reflecting dilution by quartz minerals. A double-normalization diagram is proposed to correct from dilution effects. Elements define fan-shaped patterns and can be classified in three different groups with... |
