Carboniferous palynology in Midcontinent North America

摘要

Palynofloras derived mainly from coal beds in the Illinois and Midcontinent basins show distinct trends in taxonomic composition and dominance up through the succession, with only minor differences between the basins. The few studied Upper Mississippian (Chesterian) coals are dominated by Lycospora, with other genera represented, including Schulzospora. Morrowan coals are dominated by several species of Lycospora, with many other genera and species represented, including first appearances of Laevigatosporites and Florinites, and the last occurrence of Schulzospora. Atokan coals are also dominated by various species of Lycospora, but are characterized by the appearance of many new taxa, including Endosporites globiformis and Microreticulatisporites nobilis at the base. Desmoinesian coals show decreasing spore diversity and decreasing dominance of Lycospora, with some coals dominated by fern spores, including the first appearance of species of Thymospora at the base. Missourian and Virgilian coals show an abrupt decrease in diversity at the Desmoinesian-Missourian boundary, with disappearance of Granasporites and near disappearance of Lycospora, which dominated miospore assemblages in the Early and Middle Pennsylvanian. Seed fern and tree fern spores became the most abundant miospores in the Late Pennsylvanian.