Clustering of Ultra-Large Landslides in the Upper Yellow River Based on Optically Stimulated Luminescence (OSL) Dating

Dating landslides is essential for establishing the temporal framework needed to link landslide occurrence with tectonic uplift, climate change, and river incision, and for assessing the stability of ancient landslide slopes. Although previous studies have dated landslides using a variety of methods, these methods have been constrained by difficulties in sample acquisition or limits on their effective dating range. To address these limitations, in this study, 10 ultra-large ancient landslides in the Longyangxia–Jishixia section of the upper Yellow River, which were selected based on their geological structure, stratigraphy, and lithology, were sampled at specific points for optically stimulated luminescence, using five different approaches. The reliability of each sample was tested, and the results were used to investigate the relationship between geological time, climate change, and the clustering of landslides. OSL dating is feasible for these deposits when supported by clear stratigraphic contacts, bleaching tests, and independent validation. The ultra-large landslides in the study area yield four provisional age groups (130–110, 50–30, 12–9, 5–3 ka; 95% HPD after uncertainty propagation). The primary cause of landslide clustering in each period was also determined. The clustering was primarily controlled by tectonic uplift associated with the Gonghe Movement and by climate-driven increases in rainfall and river erosion.