Bauxite Deposits in China; High Aluminous Shale

Abstract

Many bauxite deposits, high aluminous shales, are distributed in Sino-Korean and Yangtze paraplatforms in China. Most of them cover unconformably the Ordovician and Silurian systems, and are stratigraphically correlated to the middle to upper Carboniferous age.
The bauxite ores in Jiaozuo and Xiaoguan areas, Henan province, are composed mainly of diaspore, in association with 2M type sericite, pyrophyllite and kaolinite. Fe/Mg chlorites, geothite and hematite are dominant in the lower part of the bauxite layers and in the ferrugineous clay beds accumulated on karst sinkholes. The occurrence of ore deposits and their mineral association suggest that the bauxite were formed under a low pH and low Eh condition in the large-scale karst basins consisting mainly of the Ordovician limestones.