Petrography and geochemistry of carboniferous coal seams in the Donets Basin (Ukraine): implications for paleoecology

economically important seams from the (south)western Donets Basin are studied using organic petrographical, inorganic geochemical, and organic geochemical techniques. The main aim of the study is the reconstruction of peat facies of Serpukhovian (Mississippian) and Moscovian (Middle Pennsylvanian) coals. Formation of major coal seams commenced during Serpukhovian times. Early Serpukhovian coal accumulated in a relatively narrow shore-zone and is rich in inertinite and liptinite. Very low ash yields, low to moderate sulphur contents, and upward increasing inertinite contents suggest coal deposition in raised mires. Moscovian coal has a significantly wider lateral extension and is generally rich in vitrinite. Coal properties vary widely in response to different peat facies. Low-sulphur, low-ash k(7) coal was formed in a raised mire or in a low-lying mire without detrital input. l(1) and l(3) seams containing several fluvial partings were formed in low-lying mires. Both seams are more than 2 m thick. Seams m(2) and m(3) contain high-sulphur coal, a consequence of deposition in a peat with marine influence. In contrast, I upper syngenetic sulphur content is low in the m(5)(1) (upper) seam, which was formed in a lacustrine setting. The late Moscovian n(1) seam, up to 2.4 m thick, accumulated in a swamp with a vegetation rich in bryophytes and pteridophytes. The properties of the n(1) seam are transitional between those of Serpukhovian and other Moscovian seams. Differences in maceral composition between Serpukhovian and Moscovian coals probably reflect changes in climate and vegetation type. Tuff layers are observed in the l(1), l(3), and m(3) seams. The l(3) and m(3) seams contain abundant authigenic quartz. Trace element contents are high in many seams. As contents are especially high in seams c(10)(2), k(7), l(3) and m(3). Ash in the l(3) seam contains up to 8000 ppm As. Co is enriched near the base of several seams. Maxima up to 2400 ppm occur in the ash of the k(7) and l(3) seams. Cd contents in ash are frequently as high as 30 or 40 ppm. (C) 2003 Elsevier B.V All rights reserved.