Investigating topographic and climatic controls on erosion at variable spatial and temporal scales is essential to our understanding of the topographic evolution of the orogen.In this work,we quantified millennial-sca...Investigating topographic and climatic controls on erosion at variable spatial and temporal scales is essential to our understanding of the topographic evolution of the orogen.In this work,we quantified millennial-scale erosion rates deduced from cosmogenic^(10)Be and^(26)Al concentrations in 15 fluvial sediments from the mainstream and major tributaries of the Yarlung Zangbo River draining the southern Tibetan Plateau(TP).The measured ratios of^(26)Al/^(10)Be range from 6.33±0.29 to 8.96±0.37,suggesting steady-state erosion processes.The resulted erosion rates vary from 20.60±1.79 to 154.00±13.60 m Myr-1,being spatially low in the upstream areas of the Gyaca knickpoint and high in the downstream areas.By examining the relationships between the erosion rate and topographic or climatic indices,we found that both topography and climate play significant roles in the erosion process for basins in the upstream areas of the Gyaca knickpoint.However,topography dominantly controls the erosion processes in the downstream areas of the Gyaca knickpoint,whereas variations in precipitation have only a second-order control.The marginal Himalayas and the Yarlung Zangbo River Basin(YZRB)yielded significantly higher erosion rates than the central plateau,which indicated that the landscape of the central plateau surface is remarkably stable and is being intensively consumed at its boundaries through river headward erosion.In addition,our^(10)Be erosion rates are comparable to present-day hydrologic erosion rates in most cases,suggesting either weak human activities or long-term steady-state erosion in this area.展开更多
基金Second Tibetan Plateau Scientific Expedition and Research(STEP)Program,No.2019QZKK0707National Key Research and Development Program of China,No.2020YFA0607700+1 种基金National Natural Science Foundation of China,No.41930863China Seismic Experimental Site,No.2019CSES0104。
文摘Investigating topographic and climatic controls on erosion at variable spatial and temporal scales is essential to our understanding of the topographic evolution of the orogen.In this work,we quantified millennial-scale erosion rates deduced from cosmogenic^(10)Be and^(26)Al concentrations in 15 fluvial sediments from the mainstream and major tributaries of the Yarlung Zangbo River draining the southern Tibetan Plateau(TP).The measured ratios of^(26)Al/^(10)Be range from 6.33±0.29 to 8.96±0.37,suggesting steady-state erosion processes.The resulted erosion rates vary from 20.60±1.79 to 154.00±13.60 m Myr-1,being spatially low in the upstream areas of the Gyaca knickpoint and high in the downstream areas.By examining the relationships between the erosion rate and topographic or climatic indices,we found that both topography and climate play significant roles in the erosion process for basins in the upstream areas of the Gyaca knickpoint.However,topography dominantly controls the erosion processes in the downstream areas of the Gyaca knickpoint,whereas variations in precipitation have only a second-order control.The marginal Himalayas and the Yarlung Zangbo River Basin(YZRB)yielded significantly higher erosion rates than the central plateau,which indicated that the landscape of the central plateau surface is remarkably stable and is being intensively consumed at its boundaries through river headward erosion.In addition,our^(10)Be erosion rates are comparable to present-day hydrologic erosion rates in most cases,suggesting either weak human activities or long-term steady-state erosion in this area.
