Basic chemical composition combination rules and quantitative criterion of red beds

Abstract. Red beds belong to slippery formations, and their rapid identification is of great significance for major scientific and engineering issues, such as geological hazard risk assessment and rapid response to geological disasters. Existing research often identifies red beds from a qualitative or semiquantitative perspective, resulting in slow recognition speed and inaccurate recognition results, making it difficult to quickly handle landslide geological disasters. Combined with the correlation between red beds' geomorphic characteristics, mineral compositions, and chemical compositions, this study established a preliminary identification quantitative criterion based on the basic chemical composition combination rules (SiO2+Al2O3, Al2O3/SiO2, FeO+Fe2O3, Fe2O3/FeO, K2O+Na2O, Na2O/K2O, CaO+MgO, and MgO/CaO) in the red beds. Following this, we perform principal component analysis on the basic chemical composition combination rules mentioned above. The results indicate that simultaneously meeting the following principal component features can serve as a rapid quantitative criterion for distinguishing red beds from other rocks: F1=-3.36–23.55; F2=-23.00–3.11; F3=-10.12–4.88; F4=-2.21–4.52; F5=-0.97–7.30; and F=-0.67–1.89. By comparing the chemical composition combinations of 15 kinds of rocks collected from China in this study, it is proven that the quantitative criterion proposed in this study is effective. The study results can be used for rapid identification of red beds, achieving risk assessment and rapid response to geological disasters such as landslides.