LUO Xiang-jian¹, Qin Ying¹, LU Shu-fan^1*, FU Hong-bin¹, Huang Qin², Liu Guo-dong¹

(1. Guizhou Geological Survey, Guiyang 550018, China; 2. 113 Geological Team, Bureau of Geology and Mineral Exploration and Development Guizhou Province, Liupanshui 553000, China)

Abstract: The newly discovered "paleocontinental sedimentary type" rare earth elements (REE) resources in the REE-rich rocks are widely and continuously distributed on the top of Late Permian basalt in the western Guizhou, with thicknesses of 2-16m, average REO grades of 0.12%-0.15%, and the highest REO grade of 1.60%. As a new type of the REE deposit, it has been relative poorly researched, and its ore-bearing lithologic association and sedimentary facies belts are not clear. These shortcomings hinder the theoretical study and ore-prospecting prediction of the REE resources in this area. On the basis of collecting a lot of basic geological data and previous research results, combined with field investigation and trace elements test results, we have carried out the analysis of sedimentary facies of the REE-rich rock series in this paper. The study shows that the REE-rich rock series on the top of basalt in the western Guizhou is composed of three lithologic segments from bottom to top, namely, the ferruginous rock segment, the aluminous rock segment and the clastic rock segment at the bottom of the Xuanwei Formation. Especially, the ferruginous, aluminous, and clastic rocks belong to the eluvial plain, the lacustrine, and the river-delta plain facies, respectively. Therefore, we have proposed that the REE ore-rich aluminous rock is of the lacustrine facies sedimented under the control of paleotopography and landform, then have identified that the sedimentary patterns of the aluminous rock in the western Guizhou from west to east are the lake, uplift, lake, tidal flat facies, respectively, and finally have estabblished a model of the three-stage sedimentary facies of the REE-rich rock series from the base one formed by the weathering and denudation of the Emeishan basalt, to the middle one formed by the lake sedimentation in hot and humid climate, to the top one formed by the river sedimentation.

Keywords: sedimentary facies; the REE-rich rock series; Late Permian; Guizhou