Late pleistocene erosion rates of Gushan mountain, Southern Shanxi Rift, North China: evidence from cosmogenic 10Be and 26Al

Abstract

Erosion serves as a critical link connecting various geological factors that shape landforms, making the quantitative studies of erosion rates of great significance for understanding landscape evolution. In this paper, we first quantified the bedrock erosion rates of the Gushan Mountain in the southern Shanxi Rift, using in-situ produced cosmogenic ¹⁰Be and ²⁶Al. The results show that the minimum exposure ages range from 115.4 ± 7.2 ka to 26.5 ± 1.7 ka, with erosion rates varying between 5.2 ± 0.3 mm/ka and 23.6 ± 1.5 mm/ka. Ridge samples exhibit erosion rates approximately twice as high as summit samples, suggesting spatial variability in erosion processes and significant influences of topygraphy. The erosion rates of the Gushan Mountain are significantly lower than the basin erosion rates in the Taihang Mountains, suggesting landscape disequilibrium. These rates are comparable to denudation rates derived from low-temperature thermochronology, pointing to a long-term slow-paced landscape evolution of the Gushan Mountain. However, they are significantly lower than denudation rates in adjacent mountains (e.g., Taihang and Zhongtiao Mountains), highlighting the dominant role of tectonic activities in controlling erosion. The differential tectonic activities between the E’mei Platform (hosting Gushan Mountain) and the surrounding mountains of the Shanxi Rift has contributed to observed spatial variation in erosion rates. Notably, the uplift of the E’mei Platform during the Late Pleistocene had a negligible impact on the erosion of the Gushan Mountain.