Provenance of Permian Li-rich Karst bauxite in western Guangxi, China: Evidence from geochemistry, zircon U-Pb and Hf isotopic compositions of contemporaneous-heterophase tuffaceous rocks

Graphic abstract. The correlation diagrams showing the genetic relation between tuffaceous rocks and Li-rich karst bauxite deposits. • The Upper Permian Linghao Formation tuffaceous rocks and Pingguo Li-rich karst bauxite deposits in western Guangxi, China represent contemporaneous-heterophase deposits formed at ∼259 Ma. • A major volcanic eruption episode supplied the source materials for both the Linghao Formation tuffaceous rocks and Li-rich karst bauxite deposits. • The primary volcanic ash source exhibits definitive arc-related with minor mantle-derived contributions, thereby identifying the Paleo-Tethyan magmatic arc as the dominant provenance. Karst bauxite deposits are an important potential lithium resource, distinct from grantie-pegmatite, brine, and volcanic-sedimentary lithium. Pingguo Li-rich karst bauxite deposits in Youjiang Basin, South China represent major deposits hosted in the Heshan Formation deposited on the Late Permian carbonate platform. Contemporaneous-heterophase tuffaceous rocks of the Upper Permian Linghao Formation distribute widely surrounding the Pingguo Carbonate Platform. The tuffaceous rocks provide a definitive tracer for the provenance of Li-rich karst bauxite deposits. Integrated geochemical, zircon U-Pb chronology, and in situ Hf isotopic analyses reveal that both tuffaceous rocks and Pingguo Li-rich karst bauxite deposits formed synchronously at ∼ 259 Ma from the same source. The correlations of Zr-Hf, Nb-Ta, and Th/Sc-Zr/Sc confirm the genetic relation between tuffaceous rocks and Li-rich karst bauxite. Zircon trace elements fingerprint arc-related signature of the parent source. Critically, the Hf isotope compositions of the tuff (ε Hf (t)≈-4.0, T DM2 ≈1.5 Ga) indicate unequivocally with the Paleo-Tethyan magmatic arc, demonstrating that volcanic ash derived from Paleo Tethys. The provenance of Li-rich karst bauxite deposits in Pingguo Carbonate Platform was volcanic ash from Paleo-Tethyan arc. The volcanic ash covered the carbonate platform during the latest Middle Permian and early Late Permian and resulted in the formation of Li-rich karst bauxite, revealing the Paleo-Tethyan arc as the main source for the significant deposits.