Donald R. Chesnut

Comparison of the Eastern and Western Kentucky coal fields (Pennsylvanian), USA—why are coal distribution patterns and sulfur contents so different in these coal fields?

Abstract More than 130 Mt of Pennsylvanian coal is produced annually from two coal fields in Kentucky. The Western Kentucky Coal Field occurs in part of the Illinois Basin, an intercratonic basin, and the Eastern Kentucky Coal Field occurs in the Central Appalachian Basin, a foreland basin. The basins are only separated by 140 km, but mined western Kentucky coal beds exhibit significantly higher sulfur values than eastern Kentucky coals. Higher-sulfur coal beds in western Kentucky have generally been inferred to be caused by more marine influences than for eastern Kentucky coals. Comparison of strata in the two coal fields shows that more strata and more coal beds accumulated in the Eastern than Western Kentucky Coal Field in the Early and Middle Pennsylvanian, inferred to represent greater generation of tectonic accommodation in the foreland basin. Eastern Kentucky coal beds exhibit a greater tendency toward splitting and occurring in zones than time-equivalent western Kentucky coal beds, which is also inferred to represent foreland accommodation influences, overprinted by autogenic sedimentation effects. Western Kentucky coal beds exhibit higher sulfur values than their eastern counterparts, but western Kentucky coals occurring in Langsettian through Bolsovian strata can be low in sulfur content. Eastern Kentucky coal beds may increase in sulfur content beneath marine zones, but generally are still lower in sulfur than mined Western Kentucky coal beds, indicating that controls other than purely marine influences must have influenced coal quality. The bulk of production in the Eastern Kentucky Coal Field is from Duckmantian and Bolsovian coal beds, whereas production in the Western Kentucky Coal Field is from Westphalian D coals. Langsettian through Bolsovian paleoclimates in eastern Kentucky were favorable for peat doming, so numerous low-sulfur coals accumulated. These coals tend to occur in zones and are prone to lateral splitting because of foreland tectonic and sedimentation influences. In contrast, Westphalian D coal beds of western Kentucky accumulated during low differential tectonic accommodation, and therefore tend to be widespread and uniform in characteristics, but exhibit higher sulfur values because they accumulated in seasonally drier paleoclimates that were unfavorable for peat doming. Hence, basin analyses indicate that many differences between the mined coals of Kentuckys two coal fields are related to temporal changes in paleoclimate and tectonic accommodation, rather than solely being a function of marine influences.

REPTILE TRACKWAY FROM THE LEE FORMATION (LOWER PENNSYLVANIAN) OF SOUTH-CENTRAL KENTUCKY

ABSTRAcr-An Early Pennsylvanian tetrapod trackway, referred to Notalacerta missouriensis Butts, was found in the Rockcastle Sandstone Member (Westphalian A, Upper Carboniferous) of the Lee Formation in McCreary County, Kentucky. Terrestrial characteristics of the trackway, such as digit length, claw marks, gait, and tail drag, suggest that it was made by a member of the primitive reptile family Protorothyrididae. If identified correctly, this is the oldest known reptile trackway in North America. The animal that made the trackway was approximately 0.4 m in length. The pes tracks are slightly larger and set slightly wider than the manus tracks; digits are elongated and slender, and the fourth digit of the pes is the longest. Whereas the slender, long toes indicate a terrestrial form, the gait was more advanced than the sprawling gait typical of the most primitive tetrapods.

An in situ occurrence of coal balls in the Amburgy coal bed, Pikeville Formation (Duckmantian), central Appalachian Basin, USA

Carbonate concretions containing permineralized peat, commonly called coal balls, were encountered in the Amburgy coal, a generally low-ash (9.4%), but commonly high-sulfur (3.6%), Middle Pennsylvanian coal of the Eastern Kentucky Coal Field. These are the first coal balls from the Amburgy coal, and one of only a few reported occurrences from the central Appalachian Basin. The coal balls occur in the upper part of the coal, between two paleochannel cutouts at the top of the Pikeville Formation, and immediately beneath a scour with a marine fossil lag at the base of the Kendrick Shale Member, Hyden Formation. The coal is thickest (1.3 m) in a narrow (<300 m), elongate depression between the bounding paleochannels, and thins toward the occurrence of coal balls. Total biovolume as measured from acetate peels of coal balls indicates cordaites or lycopsid (36.1% each) dominance. Vertical sampling through one coal-ball aggregate shows zoning from a lower cordaites-dominant (88.7%) assemblage, to a middle, degraded, sphenopsid-rich assemblage, to an upper lycopsid-dominant (88.6%) assemblage. Beneath the coal balls, palynologic and petrographic analyses indicate the basal and middle portions of the bed are dominated by arborescent lycopsid spores and cordaites pollen, and by vitrinite macerals. The top part of the bed, above the coal balls, contains increased inertinite macerals, increased percentages of small fern spores, and variable ash yield (5-21%). Thickening of the Amburgy coal along a structural low, in combination with basal high-ash yields, vitrinite-dominance, and heterogeneous palynoflora, indicate paleotopographic control on initial peat accumulation. Abundant lycopsid spores in the basal and middle part of the coal reflect rheotrophic conditions consistent with accumulation in a paleotopographic depression. Apparent zonation preserved in one of the coal-ball masses may document plant successions in response to flooding. Similar percentages of cordaites and lycopods, respectively, in the zones above and below the degraded incursion interval reflect development of a mixed, successional pattern in response to the flooding. Coal-ball formation may have been facilitated by channeling along the Kendrick ravinement, within a paleotopgraphic depression, at the split margin of the Amburgy peat, either through direct transmittal of carbonates and marine waters into the peat, or through degassing of the peat beneath the scour.

Color-banded gastropods from the Kendrick Shale Member (Middle Pennsylvanian, Westphalian B) of eastern Kentucky

Very well preserved gastropods, with preserved color banding, are common in a newly discovered site in the Eastern Kentucky Coal Field. The fossils occur in calcareous silty shales of the Middle Pennsylvanian Kendrick Shale Member of the Breathitt Formation. Three genera of gastropods, Bellerophon, Straparollus , and Ianthanopsis , have been found with preserved color patterns.

Sedimentology of Pennsylvanian Sandstone from Bedding-Plane Exposures, Laurel Dam Spillway, Eastern Kentucky Coalfield: ABSTRACT

Exposures of bedding planes in a coarsening-upward sequence of the Breathitt Formation at the Laurel Dam spillway in Whitley County, Kentucky, were analyzed by surveying a 250,000-ft{sup 2} area on a 10-ft grid and mapping within grids.