Geochemical Characteristics of Eolian Deposits in the Chengdu Plain of Sichuan Province and the Implications for Provenance

Abstract

AbstractIn this study Chengdu Red Earth (CRE) from the Chengdu Plain (CP), Sichuan province, was analyzed for its elemental (major and trace elements) and isotopic (Sm‐Nd) geochemistry and compared with Pleistocene loess and paleosol samples from the Chinese Loess Plateau (CLP) in Northern China. The geochemical composition of CRE is similar to north China loess, and also resembles the average UCC. This indicates that CRE, as loess deposits in Northern China, was derived from well‐mixed sedimentary protoliths that have undergone numerous upper crustal recycling processes. However, obvious differences in the geochemical characteristics of CRE and the north China loess are also revealed in our results. For chemically stable elements, CRE has higher Ti, Zr, Hf and lower σREE, Ba contents in comparison with loess samples from the CLP. Further analysis shows that CRE has higher TiO2/Al2O3, SiO2/Al2O3, Ba/Rb and lower Ce/Yb, Eu/Yb, LaN/YbN and σLREE/σHREE ratios. In Sm‐Nd isotopic geochemistry, Sm and Nd content and the εNd(0) value in CRE are significantly higher than those in north China loess. The higher TiO2 content in CRE coincided with a high background concentration of Ti in the Sichuan Basin and the surrounding regions. The lower σREE and higher Sm, Nd, σNd(0) values are related to the wide distribution of basalt in the southwest Sichuan Basin. The elemental and isotopic geochemistry of CRE indicates that eolian materials in the CP predominantly come from the Sichuan Basin and the surrounding regions, which differs from loess deposits in the CLP.