Comparative Paleoclimatic Evaluation and Multivariate Analysis of Cretaceous Karst Bauxites from Central (Abruzzi) and Southern Italy (Campania and Apulia)

Karst bauxites preserve geochemical signatures of weathering processes and may provide insights into past climatic conditions. This study presents an integrated geochemical and paleoclimatic assessment of 96 samples from five Italian bauxite districts: Abruzzi, Murge, Gargano, Matese, and Caserta. Previously published whole–rock geochemical data were compiled and re–evaluated using weathering indices (CIA, CIA–K, and CALMAG), the Paleoclimatic Weathering Index (PWI), temperature and precipitation estimates (MAT and MAP), provenance–related diagrams, and multivariate statistical analysis. The results reveal significant differences among districts. Matese records the highest median mean annual temperature (MAT ≈23.5 °C) and precipitation estimates (MAP–CALMAG ≈1818 mm/yr), followed by Caserta and Murge, whereas Abruzzi records lower temperatures despite high estimated precipitation. Gargano displays the greatest variability in geochemical composition and reconstructed paleoclimatic parameters, indicating the presence of distinct geochemical populations. Provenance–related diagrams further highlight differences in parental–material affinity, underscoring the potential influence of initial composition on weathering indices and climatic estimates. Comparison with the Cretaceous climatic framework reveals temporal overlap between some bauxite-forming intervals and major climate phases, including the Cenomanian–Turonian Thermal Maximum. These results provide new comparative paleoclimatic insights into Italian karst bauxites, while highlighting the need to consider provenance and post–formational processes when interpreting climatic signals.