Relationships between trace element abundances and depositional environments of coals from the Zhangji coal mine, Anhui Province, China

Coal characteristic and trace elements of 254 coal samples from Zhangji Coal Mine, Anhui Province, China were studied. Compared with average concentrations of trace elements in Chinese, U.S. and world coals, the coals from Zhangji mine contains a higher concentrations of Co, Cu, Sr and Sc and lower concentrations of Ba, Bi, Mn, Cd, Mo and Zn. The concentrations of B and the Sr/Ba ratios showed that the Permian coal-bearing sequences of the coal mine were developed from a brackish-water influenced lower delta plain (No. 6-2 coal) to a freshwater influenced fluvial upper delta plain (No. 9-1 coal) and suffered frequent marine transgression and regression, which may cause many thin and unstable coal seams. The vertical variations of trace elements in different coal seams indicate that the concentrations of most trace elements in coals are significantly related with depositional environments. Some trace elements could be utilized in coal seam correlation.