Occurrence mode of selected elements of coal in the Ordos Basin

High concentrations of Al, Li, Ga, rare earth elements and yttrium, U and Ba in the Ordos Basin have been reported separately by lots of authors. These elements have even formed coal-associated deposits in some coalfields. The purpose of this review paper is to summarize their accumulation mechanisms and set up a mode of occurrence of these elements in the entire Ordos Basin. The Al and rare elements show different patterns of distribution and affinity relationships with organic and inorganic matter. The strong peraluminous granites and moyite from the Yinshan Oldland and Lüliang Peninsula may be the main source of the Al and rare elements in the coals. The carriers of barium are witherite and strontianite, both of which are of epigenetic origin. It is inferred that the barium was originated from the Ba-ore deposits in the black shales in the Qinling Mountains, located to the south of the Ordos Basin. Uranium deposits occur near the margin of the basin and are mainly hosted in sandstones of the Jurassic.