Features of rare earth elements and paleoenvironment of Wushan Loess in the Three Gorges, Yangtze River

This paper is result of environmental geological survey engineering.

Objective The representative dust deposit, the Wushan Loess located in China's northern subtropical river valleys, is a significant indication of environment near the Three Gorges region.

Methods In this study, we collected samples from the Wushan Loess and analyzed rare earth elementary composition to discuss paleoclimatic significance of Wushan loess.

Results Our new data show the four following implications. (1) The REE contents in each sample changes synchronously with little difference. The contents of LREE is much higher than that of HREE in each sample, suggesting the enrichment in LREE and loss in HREE. (2) The increasing of ∑REE with age in Wushan Loess is probably related to the strength of weathering the in Wushan Loess. (3) For samples from various depth, REE distribution patterns, δCe, δEu, La/Yb, Gd/Yb and ΣREE do not change significantly with depth. (4) The REE distribution patterns of all samples display negative slope, steep La-Eu curves and flat Eu-Lu curves, which suggests that certain differentiation between LREE and HREE has occurred. (5) The δEu values of Wushan Loess distributed within the interval of 0-1 on the vertical axis show obvious negative Eu anomalies andstable δCe values around 1. This implies that sediment in the upper Yangtze River did not suffer strong weathering in the period of Wushan Loess.

Conclusions Wushan Loess have not been through intense weathering effect, the climate of its region while accumulation was colder and drier in the later period than it was in the earlier period, and no obvious change has been found in the source of its materials during the accumulation process.