Large-scale erosion rates from in situ-produced cosmogenic nuclides in European river sediments

We have calculated long-term erosion rates of 20-100 mm/kyr from quartz-con tained Be-10 in the bedload of middle European rivers for catchments rangin g from 10(2) to 10(5) km(2). These rates average over 10-40 kyr and agree b roadly with rock uplift, incision and exhumation rates, historic soil erosi on rates. and erosion rates calculated from the measured sediment loads of the same rivers. Moreover, our new erosion rate estimates correlate well wi th lithology and relief. However, in the Regen, Neckar, Loire, and Meuse ca tchments, cosmogenic nuclide-derived erosion rates are consistently 1.5-4 t imes greater than the equivalent rates derived From measured river loads. T his may be due to the systematic under-representation of high-magnitude, lo w-frequency transport events in the gauging records which cover less than a century. Alternatively the discrepancy may derive from spatially non-unifo rm erosion and preferential tapping of deeper sections of the irradiation p rofile. A third explanation relates the high cosmogenic nuclide-derived ero sion rates to inheritance of an elevated Pleistocene erosion signal. Uncert ainties associated with the cosmogenic nuclide-derived erosion rare estimat es are not greater than the potential errors in conventional estimates. The refore, the cosmogenic nuclide approach is an effective tool for rapid, cat chment-wide assessment of rime-integrated rates of bedrock weathering and e rosion, and we anticipate its fruitful application to the Quaternary sedime ntary record. (C) 2001 Elsevier Science B.V. All rights reserved.