Erosion and Predicted Sediment Composition

The mean erosion rate, calculated as long-term (1 Ma) erosional budget instead of sediment yield, is 178mm/ka for the total area and 206 mm/ka if only the 19 basins are calculated, maximum values being 850 mm/ka. During the reference time of 1 Ma the entire area would have been able to produce a sedimentary deposit of 100 x 100 km, 55 m thick, with a calculated pore volume of 50%.Corresponding to the “high gradient belt”, a belt of high erosion can be established. Rock-specific erosion rates in the single basins reveal that one and the same rock type yields different erosion rates due to different positions in the mountains.The effective composition of a basin is the area percentage of its rock types weighed by its erosion rates. This effective composition may also serve as predicted sediment composition, a reference level for the provenance discussion.Shifting from the pure areal to the effective composition, granitic rocks drop from 24 to 15%, metamorphic rocks go from 37 to 41% and sedimentary rocks from 39 to 44%.