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The Danxia geoheritage has emerged as a compelling subject of study, while the Tethys-Himalayan tectonic domain continues to captivate scholarly attention. However, a noteworthy gap exists in the literature concerning the intricate relationship between Danxia formation and the evolution of regional tectonics. In this study, we conducted a comprehensive analysis involving structure interpretation and terrain assessment, utilizing Landsat8 imagery and ASTER Global Digital Elevation Model. Additionally, field investigations were carried out on 35 Danxia landforms in the southern Sichuan Basin. Our findings revealed four distinct types of Danxia heritages—cliff (32 sites), peak (7 sites), cave (5 sites), and valley (6 sites)—with a predominant presence on slopes exceeding 40°. Moreover, valley-type sites exhibited a propensity for development at altitudes surpassing 400 m. The observed formations were intricately linked to Late Jurassic to Cretaceous red beds, influenced by the synergistic effects of the southward thrusting of the Qinling Orogen and the northwestward expansion of the Jiangnan Orogen. The control exerted by Cenozoic faults, folds, and joints—resulting from the eastward expansion of the Tibetan Plateau and the southeastward extrusion of the Chuandian terrane—further shaped these Danxia landscapes. Notably, the eastward expansion of the Tibetan Plateau induced the Cenozoic uplift of the southern Sichuan Basin, initiating a rapid denudation process of red beds crucial to the formation of Danxia landforms. Consequently, the Tethys-Himalayan tectonic evolution not only provided the material and structural foundations for these formations but also exerted a profound influence on their development in the southern Sichuan Basin. This study significantly contributes to our enhanced understanding of the spatial distribution of Danxia landforms in China. [ABSTRACT FROM AUTHOR]

Many of the sandstones at cultural heritage sites around the world are susceptible to chemical weathering, and long-term monitoring of the chemical weathering would be of great value for heritage conservation and would also provide reference data for environmental protection policies and projects. Reflectance spectroscopy is a potential tool for monitoring sandstone weathering due to its non-destructive characteristics. In this paper, we present the results of an investigation into the reflectance spectra of sandstones at the Yungang Grottoes, China, where the sandstones are variously fresh, calcite-dissolved, or argillitic-altered. We found several spectral absorptions, including those at 490, 675, 900, 1410, 1918, 2205, 2330, 2350, and 2380 nm. The absorptions at 490, 675, and 900 nm are related to hematite cement, while that at 2330 nm is associated with calcite cement. The absorptions at 1410, 2205, 2350, and 2380 nm are induced by the Al-OH vibration of kaolinite, and that at 1918 nm is related to crystal water. The calcite-dissolved sandstones have lower absorption intensities at 2330 nm than fresh sandstones, and the argillitic-altered sandstones have lower absorption intensities at 490, 675, and 900 nm than the fresh sandstones. In the 1st-derivative reflectance plots, the absorption peaks at ∼1400 nm shift towards shorter wavelengths with increasing kaolinite contents. The spectral features of the fresh, calcite-dissolved, and argillitic-altered sandstones are all different, and this means they can be distinguished spectroscopically, which demonstrates the usefulness of reflectance spectroscopy for the long-term monitoring of sandstone weathering in the Yungang Grottoes. [ABSTRACT FROM AUTHOR]