Clay Mineral Assemblages as Proxies for Paleoweathering in Mesozoic Basins

Clay mineral assemblages preserved in sedimentary successions provide valuable insights into paleoweathering intensity, paleoclimate variability, and source-area evolution. This study investigates the distribution and geochemical characteristics of clay minerals in representative Mesozoic continental and marginal-marine basins to reconstruct weathering regimes and climatic trends. Using X-ray diffraction (XRD), scanning electron microscopy (SEM), and bulk geochemical analyses, relative abundances of illite, smectite, kaolinite, chlorite, and mixed-layer clays are quantified and interpreted within a stratigraphic framework. Results indicate systematic vertical and lateral variations in clay mineral composition corresponding to shifts in climatic conditions and tectonic activity. Kaolinite-enriched intervals reflect intensified chemical weathering under warm and humid climates, whereas illite–chlorite dominance suggests cooler or more arid conditions with reduced leaching intensity. Smectite-rich assemblages commonly indicate seasonally dry climates or volcanic input influencing basin sedimentation. Integration of clay mineral indices with chemical weathering proxies such as the Chemical Index of Alteration (CIA) reveals strong correlations between mineralogical patterns and geochemical signatures. Temporal trends across Mesozoic successions suggest episodic climatic fluctuations, including greenhouse phases and regional hydrological changes linked to tectonic uplift and basin reorganization.