Geochemical characteristics of the eolian deposits in the Zoige basin and their implications for provenance and weathering intensity

摘要

Eolian deposits in the Zoige basin at the northeastern region of the Tibetan Plateau (TP) were analyzed for their major-trace elements and Sm-Nd isotopic compositions to explore the provenance and weathering intensity. The results are compared with the data from the Lingtai section (LT) in the Chinese Loess Plateau (CLP). Eolian deposits from different sections in the Zoige basin have resembling geochemical compositions, reflecting similar provenance. Their major element compositions are close to those of the UCC, and their UCC-normalized major-trace element abundances and chondrite-normalized rare earth element (REE) abundances are similar to the LT samples. However, the SiO2, Al2O3, TiO2, Zr, Hf, Sc, Co, V, Ni concentrations and SiO2/TiO2, TiO2/Al2O3, Co/Th, La/Sc, Th/Sc, epsilon(Nd)(0), Sm-147/Nd-144 ratios of the Zoige sections are quite different from those of the LT section, which suggests different provenances for the eolian deposits in these two regions. The relatively high abundances of SiO2, Zr, Hf and low abundances of trace elements indicate that local sediments on the TP are the major contributors to the eolian deposits in the Zoige basin. Eolian deposits from the Zoige basin have experienced the early Na and Ca removal stage, and chemical weathering parameters suggest a moderate weathering condition in the source and deposition regions.