Determination of erosion rates along actively growing mountain ranges at the NE margin of Tibet using cosmogenic 10Be

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Actively growing mountain ranges at the northeastern edge of the advancing Tibetan Plateau offer the unique opportunity to study the competing effects of uplift and erosion during the early stages of mountain building. The shape of elongate mountain ranges in this region reflects the displacement distribution on thrust faults at depth: elevation reaches a maximum near the center and decreases linearly toward the tips. As a consequence, catchments in these ranges show a systematic decrease in relief and mean slope from the central parts of the ranges to their tips. The goal of the proposed project is to determine spatially-averaged erosion rates for catchments situated along these ranges from the concentration of cosmogenic 10Be in quartz samples from active streams. Field investigations and the analysis of digital elevation models will constrain the active erosion processes and the geomorphic signature of the hillslopes and channels in these catchments. For ranges consisting mainly of one rock type, this approach allows to decipher the relationship between erosion rate and geomorphic parameters like relief and slope. By comparing erosion rates from catchments with different rock types, the dependence of erosion rates on lithology will be quantified.