Comparative Study of Triassic-Jurassic and Early Paleocene Bauxites from Neo-Tethys: Insights into Paleoclimate Trends and Critical Raw Materials Potential

Abstract

Bauxite deposits, developed preferably during various greenhouse climate phases in Earth history, offer an excellent potential to understand and reconstruct the effects of climate and tectonics on the formation of lateritic profiles, bauxite formation, distribution and enrichment of critical raw materials (CRMs). In this study, a comparative study is conducted based on the Triassic–Jurassic Boundary (TJ) and Early Paleocene (P) bauxite deposits of the northwestern Himalayas, Pakistan, through mineralogical, geochemical, weathering indices, Pearson correlation, and Principal Component Analysis (PCA). Higher concentrations of kaolinite, boehmite, hematite and goethite along with high CIA, CIW, and PIA ratios give clear evidence of intensive chemical weathering in both bauxite deposits. However, the lateritic TJ-bauxites show comparatively homogeneous weathering profiles, while the karstic P-bauxites indicate diverse mineralogical and geochemical compositions due to karstic and sedimentary influences such as reworking. These bauxites have been enriched in Sc, Ga, V, Nb, Ta, Hf, Zr and REEs by means of the residual enrichment of relatively immobile elements during long-term lateritization. The results of multivariate statistical analysis revealed that desilicification and residual enrichment played key roles in the process of element redistribution, while parent rock type and geological evolution controlled geochemical variability. The European Union 2023 Critical Raw Materials strategy reveals the importance of the studied deposits in the supply of such critical raw materials as Sc, Ga, HFSE and REEs. This study sets a baseline for comparative research of greenhouse-related bauxite genesis and geological controls on the enrichment of CRMs.