Accumulation of trace elements in coals from various basins of Russia

The average concentrations of trace elements in coals from the South Fergana, North Sos’va, Kizelovsk, South Yakutian, Transbaikalia, Pechora, and Zyryansk deposits and some deposits of the Kuznetsk and Primor’e Basins are compared. The degrees of trace element concentration were calculated both on a total coal weight basis (Qi) for individual basins and on a mineral matter basis (QiA) with reference to Clarke numbers in clay rocks. Ratios between the concentrations of typomorphic trace elements on a coal mineral matter basis were calculated for the deposits of basins with different geologic-geochemical formation conditions (XiA); the concentration ratios between the pairs of typomorphic trace elements in the considered coal basins (Zi) were also calculated. Typomorphic elements are the trace elements with Qi > 1.4 or QiA > 2. Coal basins of different origin have different numbers of typomorphic trace elements calculated in terms of the parameter Qi and, to a lesser degree, the parameter QiA. Coal basins differ considerably from each other in both the ratios between the average concentrations of the same trace element in the mineral matter of coal (parameter XiA) and the ratios between the concentrations of two different trace elements (parameter Zi). In the basins under discussion, the mineral matter of coals from formations created in areal rift genesis regions, in particular, Triassic-Jurassic coals and, to a lesser degree, Carboniferous coals, are enriched in trace elements to the greatest extent. Coals from subgeosynclinal formations have a maximum number of typomorphic trace elements (in terms of the average concentrations in the mineral matter), practically the majority of the test elements with the exception of Nb, Sn, Ni, and Sc. Coals from young mobile platforms are characterized by a similar number of typomorphic trace elements with the exception of Nb, Zn, Y, and Yb. Coals from geosynclinal formations have a somewhat smaller set of typomorphic trace elements, whereas a minimum number of typomorphic elements is characteristic of coals from platform basins.