ZHAO Yi-meng1,3, LIU Qing-qing2*, WANG Xue-qiu2, ZHOU Jian2, XIA Yong1, TAN Qin-ping1*
(1. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; 2. Institute of Geophysical and Geochemical Exploration, CAGS, Langfang 065000, China; 3. University of the Chinese Academy of Sciences, Beijing 100049, China)
Abstract: There is a large REE soil geochemical anomaly, which is centered in the Xuanwei area, in the conjunction area of Guizhou, Yunnan, and Guangxi provinces, China. In this study, soil (red clay) and various kinds of rocks (basalt, dolomite, limestone, sandstone, siltstone, mudstone, tuff, and shale) in the Xuanwei area have been collected for analyzing contents of the REE and trace elements, and organic matter (Corg) composition, and measuring pH values in order to explore the REE source of soils in the area. The results show that the REE content of soils are about two times higher than that of the upper continental crust. The REE contents of basalt samples are consistent with those of the overlying soils, but the REE contents of sedimentary rocks (dolomite, limestone, and sandstone) are far below those of the overlying soils. The REE contents of the soil samples have excellent correlation (r > 0.7) with their contents of Co, Ni, Cu, Zn, and Au, which are normally rich in basic rocks, but have no obvious correlations with pH values (r=0.33) and organic matter contents (r=0.20). The REE distribution patterns of basalts are highly consistent with those of the overlying soils, while REE patterns of sedimentary rocks are quite different to those of the overlying soils. In addition, the REE pattern of median values of all soil samples is exactly similar with that of the basalt. Although basalt and marine sedimentary rocks are both exposed in the Xuanwei area, the basalt may be the main source of REE in soil samples in the REE geochemical anomaly area.
Keywords: REE; geochemical anomaly; weathering of basalt; the southwestern China
ACTA MINERALOGICA SINICA Vol. 39, No.4, 2019, page 432-442
