Elemental Affinities in Coals from the Southern Qinshui Basin, North China

摘要

The occurrence and distribution of major, trace and rare earth elements have been investigated in two coal-bearing units in the Qinshui Basin, northern China: the Carboniferous and Permian coals. The arithmetic means of concentrations for most elements in the Carboniferous and Permian coal samples, although in a relatively low level, is present in the range of the world concentrations. The coals in the Late Carboniferous Formation are enriched in Ca, Fe, Mg and Cd, while the coals in the Early Permian are enriched in P, Ti, Ba and Nb. There are no distinct differences of Al, Na, Be and other elements in these two strata. Five groups of the elements in the Carboniferous and seven groups of the elements in the Permian may be classified according to the mode of occurrence in coals. Major differences found between the Carboniferous and Permian coals are probably related to the different depositional setting, given that the Carboniferous coals were deposited on a tidal flat, and the Permian coals were accumulated in delta plain environment.