PALYNOLOGIC, PETROGRAPHIC AND GEOCHEMICAL CHARACTERISTICS OF THE MANCHESTER COAL BED IN EASTERN KENTUCKY

The Manchester coal bed in eastern Kentucky is the stratigraphically l owest coal in Kentucky that is both laterally continuous and of consis tent mineable thickness. The Manchester coal bed occurs in the lower p art of the Breathitt Formation, in an interval between the underlying Corbin Sandstone and the overlying Betsie Shale, both of which are als o aerially widespread units. The Manchester is early Middle Pennsylvan ian in age and is equivalent with the middle Morrowan of the Eastern I nterior Basin and the late Westphalian A of western Europe. Increment samples were collected from the western and eastern outcrop and mining areas of the Eastern Kentucky Coal Field and were analyzed palynologi cally, petrographically and geochemically to compare and contrast the two areas.In the western part of the Eastern Kentucky Coal Field, the Manchester coal bed is uniform in occurrence and composition. The bed is consistently 0.61-0.92 m (2-3 ft) thick, and generally is devoid of inorganic partings. Palynologically, the coal in this area is largely dominated by Lycospora, the dispersed spore of many of the large lyco psid trees (e.g., Lepidodendron and Lepidophloios) and, to a lesser ex tent, Granasporites medius (representing Diaphorodendron and Synchysid endron). Petrographically, the coal contains high percentages of vitri nite macerals and correspondingly low percentages of liptinite and ine rtinite macerals. Most of the increments from this area studied are ge nerally low in ash yield (>5%) and sulfur content (<1%), although term inal coal layers are frequently higher in ash (>10%) and occasionally sulfur (>1%). In the eastern part of the coal field the Manchester coa l bed is typically thicker (>3 ft, 1 m), but usually occurs as a coal zone with intercalated coal beds and elastic units, Palynologically, t he coal in this area contains increased percentages of small lycopsid, small (seed?) ferns, calamites, and cordaites. Petrographically, the coal is higher overall in liptinite and inertinite macerals. Ash yield s in the eastern sample area are generally low (<10%), an exception be ing some high-ash durain bands. Overall sulfur contents also are low ( typically <1%). The western samples are interpreted as having formed i n a well protected, generally flooded, mire. A consistent water cover would provide a favorable environment for arboreous lycopsid growth an d proliferation, and also inhibit oxidation of the peat surface, thus promoting the formation of a high vitrinite content coal. The eastern samples are also interpreted as having formed in a mire that was well protected most of the time, giving rise to thick sequences of low-ash, low-sulfur coal. Intermittent inundation by extra-swamp waters, carry ing sediment in this area, resulted in the development of a multiple c oal zone (i.e., several peat-forming events with intervening elastic d eposition), in contrast to a single peat-forming event in the western area. Surficial peat exposure was more frequent in the eastern area, w hich allowed for increased microbial degradation of the peat and subse quent formation of inertinite macerals upon conversion to bituminous c oal. This condition might also accelerate charring of the peat surface by wildfire.