Tectonic Controls on Surface Erosion Rates in the Longmen Shan, Eastern Tibet

Abstract

The Earth's topography results from the competition between internal processes driven essentially by tectonic fluxes and external forcing primarily affected by climate (Molnar & England, 1990). Acting as a bridge linking these two forcings, surface processes provide a source of multiple feedback mechanisms (Champagnac et al., 2012). Analyzing the amplitude and distribution of surface erosion can provide important insights to understand tectonic processes and/or climatic variation. Moreover, surface erosion might play a critical role in defining the stress distribution and regional deformation by controlling topographic variations (Avouac & Burov, 1996; Willett, 1999). Thus, in active mountain ranges, quantifying surface erosion is fundamental for understanding not only the uplift history and topographic evolution, but also geodynamic processes at depth. Over recent decades, isotopic techniques have provided new approaches for the quantification of surface erosion processes, especially the widespread use of low-temperature thermochronology (e.g., Reiners & Brandon, 2006; Willett & Brandon, 2013) and in situ produced cosmogenic nuclides (e.g., Lal, 1991; Stone, 2000). Low-temperature thermochronology allows us to quantify the exhumation rate of rocks averaged over 10 6year time scale, based on the temperature-dependent diffusion or annealing in minerals (Reiners & Brandon, 2006). Measurement of in situ produced cosmogenic nuclides in exposed rocks and fluvial sediment

Influence of Regional Erosion and Sedimentary Loading on Fault Activities in Active Fold-Thrust Belts: Insights From Discrete Element Simulation and the Southern and Central Longmen Shan Fold-Thrust Belt

“…In recent years, many important achievements have also been published in this study of erosion rates along-strike or cross-strike in major faults (Xu and Kamp, 2000;Tan et al, 2015;Gao et al, 2016;Tan et al, 2017;Tan et al, 2019;Luo et al, 2021;Wang et al, 2021), as well as the syntectonic sedimentation deposited in the LMS active fold-thrust belt (Yan et al, 2013;Li et al, 2014;Li et al, 2016;Li C. et al, 2018;Luo et al, 2021). According to previous research on the regional erosion system, at least 4-5 km of strata have been eroded in the southern and central LMS at an erosion rate of 0 mm/yr to 1.0 mm/yr from the range front to the hinterland of the LMS foldthrust belt since the late Miocene (Tan et al, 2017;Shen et al, 2019;Ye, 2021;Wang et al, 2021). In addition, the differential erosion characteristics and syntectonic sedimentary loading along-strike of the LMS fold-thrust belt were further confirmed.…”

“…The 2008 M W 7.9 Wenchuan earthquake occurred deep in the interior of the LMS fold-thrust belt, 200 km northwest of the toe of the fold-thrust belt in the Sichuan basin (Hubbard et al, 2010), accompanied by the formation of coseismic reverse-and oblique-slip surface faulting by two large thrust faults (Lin et al, 2009;Liu-Zeng et al, 2009;Xu et al, 2009;Li et al, 2010). The occurrence of this earthquake showed that the LMS fold-thrust belt is still active nowadays and is characterized by strong tectonic uplift, rapid erosion, and devastating seismic hazards (Hubbard and Shaw, 2009;Xu et al, 2009;Yin, 2010;Gao et al, 2016;Tan et al, 2017;Wang et al, 2021).…”

“…on mechanical models. Wang et al (2021) emphasized the role of tectonic structures in regulating the pattern of denudation and topography across the LMS fold-thrust belt. All these studies mentioned above indicated that denudation played an important role on the structural evolution of the LMS fold-thrust belt.…”

Channel Profiles Reveal Fault Activity along the Longmen Shan, Eastern Tibetan Plateau

“…The Longmen Shan range, situated on the eastern margin of the Tibetan Plateau, stands out as one of the most prominent and imposing topographic escarpments worldwide (Figure 1a). It features steep terrain, with the average elevation rising from approximately 600 m in the Sichuan Basin to about 4000 m within the Tibetan Plateau, all within a relatively short horizontal distance of about 70 km [21] (Figure 1b). This range is characterized by deeply dissected landscapes shaped by the tributaries of the Yangtze River.…”

“…This range is characterized by deeply dissected landscapes shaped by the tributaries of the Yangtze River. The correlation between high peak elevations and substantial relief along the Longmen Shan has led to several interpretations, including the possibility of lower crustal flow at depth [15], an isostatic response to the erosion of the plateau margin [22], or variations in rock uplift linked to active faults [21,23]. The Longmen Shan range is divided into southern, central, and northern segments based on topography and structural deformation [26][27][28] (Figure 1).…”