PALYNOLOGY, ORGANIC PETROLOGY AND GEOCHEMISTRY OF THE BELL COAL BED IN WESTERN KENTUCKY, EASTERN INTERIOR (ILLINOIS) BASIN, USA

The Bell coal bed is one of the stratigraphically oldest coals (early Middle Pennsylvanian, Atokan, Duckmantian) in the Eastern Interior (Illinois) Basin that has been commercially mined. Unlike younger (late Middle Pennsylvanian, Desmoinesian, Asturian) coals in the basin, which are thicker and more extensive in occurrence, the Bell coal occurs as a series of discontinuous pods that vary significantly in thickness and extent. Samples of coal and carbonaceous shale, collected from surface mines, drill cores and outcrops, were analyzed geochemically, petrographically, and palynologically to ascertain the origin of the Bell coal bed in western Kentucky.

The Bell coal exhibits a great deal of compositional variability, both temporally and spatially. Geochemically, the Bell coal consists of intercalated layers of coal (≤25 % ash), impure coal (>25 to <50 % ash), and carbonaceous shale (≥50 % ash). Petrographically, the Bell coal is mainly a high vitrinite coal (>80 %, mmf), with telovitrinite occurring more frequently than detrovitrinite and gelovitrinite. Certain layers, however, contain elevated amounts of liptinite and inertinite. Among the inertinite macerals, examples of both fire (e.g., fusinite) and degradation (e.g., macrinite) origin are evident.

Palynologically, the Bell coal is dominated by arborescent lycopod spores (avg. >70 %), primarily as Lycospora, with some samples containing increased proportions of spores and pollen from other Pennsylvanian plant groups. Samples with more heterogenous palynofloras commonly have elevated ash yields.

Collectively, the Bell coal is interpreted to have formed from a series of small, disconnected paleomires that formed in topographically low areas on the early Middle Pennsylvanian landscape. The mires are interpreted to have been planar and topogenous. Accumulating peat, principally from arborescent lycopod source material, was mainly well-preserved, but punctuated with intervals marked by sediment contamination, and degradation and oxidation of the surficial peat by both biologic (decay) and abiotic (fire) processes.