论广西平果铝土矿成因与沉积相的关系

Relationship between Sedimentary Facies and Genesis of the Bauxit Deposits in Pingguo,Guangxi

摘要: 被列为我国九大有色金属基地之一的广西平果铝土矿(图1),以品位高,规模大著称。

Abstract: The bauxite deposits in the Pingguo area, Guangxi may be classified into two types: primary sedimentary or karst sedimentary. The former tends to be governed by sedimentary facies. During the Permian, an isolated sedimentary system of carbonate platform was developed in the area. The Permian sedimentary facies on the ancient Pingguo carbonate platform appear to fall into the central platform facies, Platform margin facies and slope-intraplatformal trough facies. During Early Permian, bioclastic grainstones were developed in the central platform facies, organic reefs in the platform margin facies and siliceous rocks and calcirudites in the slope-intraplatformal trough facies, re-spectively.
The carbonate platform was once uplifted and exposed to the surface during the Dongwu Movement. Later in Late Permian, the mineral bauxite was transported by storm currents and became concentrated to form the deposits in the central platform facies as a result of transgression. The graded bedding and flow structure have been found in the bauxite deposits in pingguo. It is impossible for the bauxite deposits to form in the platform margin and slope-intraplatformal trough facies.
Volcanic matter may serve as one of the sources for aluminium from the bauxite deposits in Pingguo.