Evaluation of the Rock Uplift Pattern in the Central Yunnan Subblock, SE Tibetan Plateau: Based on the Bedrock Channel Profile

Abstract

The uplift pattern of the southeastern Tibetan Plateau is strongly related to the topographic evolution stemming from the India–Eurasia collision. However, whether strain is localized along major faults that bound large tectonic blocks or is accommodated across regions has been strongly debated. In this study, we used stream power incision models to obtain the distribution pattern of the channel steepness indices to understand the rock uplift pattern across the area, as increased channel steepness indices often correlate with the rock uplift rates. In this study, the river longitudinal profiles were analyzed to obtain the distribution of the channel steepness indices in the Central Yunnan subblock. The results suggested very weak correlations between the steepness indices and the lithology, precipitation, sediment flux, or channel concavity indices. Along the Xiaojiang strike–slip fault and the interior subblock, the uplift rate was slower, while the northern part had uplifted faster and was controlled by thrust fault systems. The channel steepness increased gradually from south to north. Thus, the distribution pattern of the normalized channel steepness, ksn, index within the Central Yunnan subblock provides notable support for the argument for the thrusting transformation-limited extrusion model of the Tibetan Plateau.

Spatial variation in landscape evolution of the Xiaojiang Region, SE Tibetan Plateau

“…Geomorphic indices measured at the drainage basin scale were used to capture variation in landscape form (El Hamdouni et al, 2008). Several geomorphic indices including river channel profile form and drainage basin shape were used to measure erosion and deposition processes and to detect anomalies caused by local changes in surface variation and tectonic activity (Strahler, 1952;El Hamdouni et al, 2008;Gao et al, 2013;Tsimi and Ganas, 2015;Cheng et al, 2016;Faghih et al, 2016;Cheng et al, 2018;He et al, 2019;Shi et al, 2020;Róycka and Migoń, 2021;Wang et al, 2021;Wang H. et al, 2022). Monthly precipitation data from the China Meteorological Data Network (period 1970-2019, data downloaded from http://data.cma.cn) were used to calculate the mean annual precipitation by Kriging interpolation for basins in the Xiaojiang Region (Figure 3).…”

“…The N-S-trending Xiaojiang fault extending through the Xiaojiang Region is a slip boundary for the southeastward translation of the Sichuan-Yunnan Block of the Tibetan Plateau (Tapponnier et al, 1982;Wang et al, 1998;Tapponnier, 2001;Jun et al, 2003;Li et al, 2019;Wang D. et al, 2022). From north to south, this fault changes from strikeslip to extensional and has produced a series of Quaternary basins (Tapponnier et al, 1982;Wang et al, 1998;Tapponnier, 2001).…”

“…Different models have been proposed for explaining the evolution of the southeastern Tibetan Plateau. The oblique shortening and extrusion model suggests a stepwise southeastward migration of tectonic rock uplift and surface uplift, with major fault zones accommodating large-scale crustal extrusion and/or shortening and the intensity of tectonic activity in the region gradually decreases from north to south (Tapponnier et al, 1982;Wang et al, 1998;Tapponnier, 2001;Jun et al, 2003;Tian et al, 2014;Wang H. et al, 2017;Wang et al, 2021;Zhu et al, 2021;Wang H. et al, 2022). The lower crustal flow model suggests a different deformation pattern (Clark et al, 2005;Royden et al, 2008;Yuan et al, 2022), and the entire SE Tibetan Plateau experienced uniform southeastward tilting from north to south.…”

“…In this study, we aim to assess the geomorphic variation for the southeastern Tibetan Plateau using the example of the Xiaojiang Region, which is located in the southeastern Tibetan Plateau and lies within the East Asian summer monsoon precipitation area (Figure 1A) (Wang et al, 1998;Tapponnier, 2001;Deng et al, 2003;Nie et al, 2018;Li et al, 2019;Wu et al, 2020;Wang H. et al, 2022;Yu et al, 2022). Geomorphic indices are quantitative methods that can be used to measure information about landscape form and evolution and thus infer the controls on landscape evolution (Strahler, 1952;El Hamdouni et al, 2008;Figueroa and Knott, 2010;Perron and Royden, 2013;Wang et al, 2017b;Cheng et al, 2018;He et al, 2019;Shi et al, 2020;Róycka and Migoń, 2021;Wang D. et al, 2022). In this study, we use geomorphic indices based on the analysis of digital elevation models (DEMs) to evaluate the variation in the landscape evolution of the Xiaojiang Region.…”

Characteristics of relative tectonic activity in the Longchuan River Basin, central Yunnan: evidence from digital elevation model-based geomorphological analysis

“…The Cenozoic compression of the Indian plate into the Eurasian plate led to the development of numerous striped fault zones on the surface of the Tibetan Plateau and its surrounding areas (Briais et al, 1993;Molnar et al, 1993;Tapponnier, 2001;Bai et al, 2010;Wang et al, 2015). The uplifted forces on the Tibetan Plateau were then released along the fault zones in a SE direction (Clark and Royden, 2000;Kirby et al, 2002;Godard et al, 2009;Wang et al, 2012;Wang et al, 2017;Yu et al, 2022a). Two mechanisms for tectonic deformation are present on the southeastern margin of the Tibetan Plateau: lateral extrusion of rigid blocks and eastward flow of material from the lower crust.…”