Sea-level fluctuations in the late Middle Permian estimated from palaeosols of the Sichuan Basin, SW China

Abstract

Two upper Middle Permian palaeosols, consisting of coal and pyrite intercalated with a 20 cm thick limestone, were found near Mount Emei in the SW Sichuan Basin, China. The macro- and micromorphology and physico-chemical properties, in conjunction with the mineralogical composition of the palaeosol horizons were investigated. This type of palaeosol is common within the Permian intertidal facies of the Upper Yangtze Craton. The section reflects fluctuations within the range of 0–25 m in relative sea-level, with the depositional environment changing from shallow-marine to littoral, followed by tidal-flat to littoral, and finally to continental volcanic rocks, based on a combination of palaeopedological and carbonate microfacies analyses. Such short-term relative sea-level fluctuations in late Middle Permian times in the SW Sichuan Basin of South China are consistent with the long-term falling trend on a global scale in late Middle Permian times, and may be related to regionally variable subsidence and global cooling. The combination of coastal palaeosol and carbonate microfacies analyses is proposed as an additional tool for estimating the amplitude of sea-level changes.

Multiproxy Paleosol Evidence for Jurassic Paleoclimate Fluctuations in the Sichuan Basin, SW China

“…Paleosols, known as fossil soils, can potentially provide an archive of stratigraphic, ecological, hydrologic, geographic, environmental and climatic conditions that are preserved in continental settings during their formation (e.g., Retallack, 2001;Sheldon and Tabor, 2009;Tabor and Myers, 2015;Tabor et al, 2017;Guo et al, 2019;Lü et al, 2022), especially with respect to paleoclimatic and paleoatmospheric CO 2 conditions (e.g., Huang et al, 2012;Breecker and Retallack, 2014;Xiong et al, 2015;Li et al, 2016;Gao et al, 2021). Additionally, paleosols have served as potential indicators for environmental change in response to critical geological events throughout geological history (e.g., Huang et al, 2013;Zhang L et al, 2018;Li J et al, 2020a;Retallack, 2021).…”