Abstract Middle Pennsylvanian coal-measure sequences of the eastern Kentucky coal field, central Appalachian basin, occur in ordered groupings of five to six fourth-order coal-clastic cycles, between third-order marine flooding surfaces. Lower Pennsylvanian coal measures also are present, but are laterally truncated by at least four, 60舑80-km (37舑50-mi)-wide belts of quartz-pebble-bearing quartzarenites that were deposited in a longitudinal drainage system. Successive quartzarenite belts are truncated updip by the next youngest belt. Each belt consists of at least a pair of vertically stacked, composite sandstones separated by a coal bed and estuarine or marine shale facies. Although less marine than their middle Pennsylvanian counterparts, the base of these lower Pennsylvanian midformation shales also represents marine flooding surfaces, or the updip equivalents of flooding surfaces. Therefore, lower Pennsylvanian third-order genetic sequences can be defined that include both marginward quartzarenites and basinward coal-measure facies. Changes in foreland-basin subsidence, sedimentation patterns, climate, and marine influences affected depositional sequences from the early to middle Penn-sylvanian. The westward shift of the longitudinal drainage belt was accompanied by a westward shift in basinward coal measures, resulting in increasingly more extensive coals with time. Increasing expanse and uniformity of coal measures was accompanied by decreasing foreland accommodation. In each third-order sequence, the greatest accommodation appears to occur in the regressive parts of the brackish to marine shales that bound each sequence. The greatest spatial changes in sequence thickness occur across the northern hinge line of the basin and along the basinward limit of successive quartzarenite belts. Foreland-basin subsidence influenced the stacking of successive lower Pennsylvanian quartzarenites, the westward overlap of successive quartzarenite belts, basinward increases in the number of coal beds, development of coal zones in third-order sequences, and basinward increases in the thickness of coal beds.

Abstract The potential of polar compound compositions from electrospray ionization ultra-high resolution mass spectrometry (FT-ICR-MS) to characterize petroleum fluids as well as petroleum system processes is shown in the example of the Eagle Ford Formation in Texas, USA. A set of six black oil and nine source-rock bitumen samples is investigated with respect to its organic nitrogen-, sulphur- and oxygen-compound inventory in order to assess maturity, depositional environment, lithofacies and retention and migration behaviour. Compared to conventional geochemical tools based on molecular parameters from gas chromatographic analyses, FT-ICR-MS enables a maturity assessment from immature to late mature stage, which is barely influenced by source or depositional environment. Due to the increased molecular mass and polarity range of its target compounds, FT-ICR-MS is the most convincing tool to describe the retention and fractionation of polar compounds in a petroleum system.