Many upper Middle Pennsylvanian coal beds can be readily identified and correlated by palynological methods on both an intrabasinal and an interbasinal scale. Coal palynology is also very useful in helping to reconstruct the vegetational composition of ancient mire floras, because the parent plants of most palynomorphs are known. As such, palynological analyses allow us to positively identify and trace upper Middle Pennsylvanian coal beds over large distances, while at the same time documenting changes in mire floras geographically. This paper discusses the criteria by which upper Middle Pennsylvanian coal beds can be palynologically identified and correlated. The role of palynology in helping to reconstruct the ecology of the ancient mires are also discussed, because plants are very sensitive indicators of local climatic, hydrologic, and edaphic conditions. One bed, the Lower Kittanning coal of the northern Appalachian Basin, is discussed in detail.
The Lower Kittanning coal bed has been correlated by both palynologic and lithostratigraphic methods across three coal basins (Appalachian, Eastern Interior, and Western Interior). Results indicate that the Lower Kittanning is equivalent with the Princess #6 of northeastern Kentucky, the No. 5 coal of southeastern Ohio, and the No. 6 Block of southern West Virginia. In the Eastern Interior (Illinois) Basin, it is equivalent with the Colchester (No. 2) coal, and in the Western Interior Basin it is equivalent with the Croweburg/Henryetta coal of Oklahoma, Kansas, and Missouri, and the Whitebreast coal of Iowa.
The palynofloras of the Lower Kittanning coal and correlative coals in the Eastern Interior and Western Interior Basins are similar in overall composition. Lycospora and tree fern spores co-dominate the palynofloras, with calamite and small lycopsid spores, and cordaite pollen, being locally abundant. Temporal patterns in all three basins are similar as well. Lycospora typically dominates the bottom third of the bed and is co-dominant with tree fern spores in the middle third. In the top third of the bed increased percentages of accessory taxa are seen, which include Calamospora, Laevigatosporites, Endosporites, Florinites, and Densosporites. Geographical differences include more abundant Densosporites in the Lower Kittanning coal of Ohio and Pennsylvania, and higher percentages of Florinites in the Croweburg coal of Oklahoma.
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Climate Controls on Stratigraphy
The role of climate as a primary control on stratigraphy is the cornerstone of this volume. The emphasis on climate is in distinct contrast to most previous studies, in which stratigraphic variability has been related to changes in sea level and in tectonic activity. Furthermore, the findings, derived from several years of detailed study of modern and ancient key geologic sections around the world, indicate that traditional depositional models generally do not fully explain the origin of fossil fuels. Although the results of the studies presented in this volume are intended to contribute to the disciplines of sedimentary geology and stratigraphy, the contributors recognize that their results may also contribute to a better understanding of global climate change. The theoretical background of climate control on sediment supply and stratigraphy is presented in the volume. With this background in place, detailed documentation and analysis of climate control on the lithologic variation of a single Middle Pennsylvanian.