Erosions on the southern Tibetan Plateau: Evidence from in-situ cosmogenic nuclides 10Be and 26Al in fluvial sediments

Abstract

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.

Quaternary evolution of the Jinshan Gorge and Yellow River: Insight from numerical modelling and terrace correlation

“…The age of the gravels may not accurately indicate the timing of terrace formation. Factors including subtle variations between sampling locations and localized events such as landslides, collapses and seismic activity, can substantially affect the reliability of TCN dating (Balco et al, 2008; Zhang, Xu, & Cui, 2022). The Yellow River in the Jinshan Gorge area has a history of transitioning from a fluvio‐lacustrine system to a fluvial system, as documented by previous studies (Li & Yang, 1991; Pan et al, 2011, 2012; Qiu et al, 2014).…”

Supplemental Material: Deciphering differential exhumation in the Gangdese orogen in southern Tibetan using exposed porphyry alteration systems and geomorphic analysis

“…Table S5. Cosmogenic 10 Be derived erosion rates from Zhang et al (2022) and corresponding averaged basin ksn calculated in this study.…”

“…(B12/B13)×(B14/B13) (Guha and Vinod Kumar, 2016) Table S5. Cosmogenic 10 Be derived erosion rates from Zhang et al (2022) biotite and hornblende are replaced by chlorite, and of plagioclase phenocrysts by epidote (Sun et al, 2021). In transitional stage (>20~80 MPa), potassic alteration started to transform feldspardestructive alteration (phyllic-argillic alteration), however this alteration distribution is limited .…”

“…Figure S3. (a) Linear fitting between 10Be based erosion rates(Zhang et al, 2022; Supplementary TableS5) and basin average ksn in the Origin software. Blue area shows the 95% confidential interval.…”

Effective soil particle size distributions and critical size of enrichment/depletion in splash erosion for loessial soil

“…Therefore, the study of splash amount and particle size sorting characteristics can help reveal the characteristics of splash and understand the soil erosion process deeply. Soil properties, rainfall characteristics and topographic factor are the main factors affecting splash erosion (Legout et al, 2005;Ma et al, 2014a;Wang et al, 2014;Yao et al, 2018;Zhang et al, 2022;Shi and Zhang, 2023), and the influences of rainfall properties and slope gradients on splash erosion are the most widely studied, especially the influences of rainfall intensity on splash erosion (Quansah, 1981;Mermut et al, 1997;Janeau et al, 2003;Ma et al, 2014b;Wang and Shi, 2015;Hu et al, 2016;Mahmoodabadi and Sajjadi, 2016;Sadeghi et al, 2017;Wu et al, 2019). However, some scholars choose the raindrop kinetic energy to investigate the splash erosion process (Qin et al, 2014;Hu et al, 2016;Sun et al, 2021).…”