The Springfield Coal Member (Carbondale Group, Petersburg Formation of Indiana) is split locally in Warrick and Gibson Counties, Indiana, by clastic rocks of the Folsomville Member (Carbondale Group, Petersburg Formation) that represent the Leslie Cemetery paleochannel, part of a large, interconnected paleochannel system in the Springfield coal bed. This study incorporated analysis of miospore and megaspore assemblages, coal petrography, plant compression fossils and conodonts from the coal and clastic split to document changes in the swamp and its vegetation in response to the activity of the Leslie Cemetery paleochannel. Palynological and petrographic data indicate that environmental conditions and vegetation in the lower bench of coal near the Leslie Cemetery paleochannel were similar to those found in profiles through the coal bed at sites near the larger, more extensive Galatia paleochannel. Miospore floras of the high-vitrinite, lower bench of coal were dominated by tree-fern miospores, with those of lycopsids ranking second in abundance; megaspore assemblages were dominated by lycopsid megaspores. Near the contacy between the lower bench of coal and clastic split, medullosan prepollen increases in abundance and fusain bands are more common, which may indicate the occurrence of fire, either within or outside the swamp. Vegetation in the Folsomville Member and upper bench of coal differ markedly from that of the lower bench of coal. Plant megafossils from the Folsomville Member indicate dominance by pteridosperms and/or lycopsids and Folsomville Member miospore assemblages are dominated by lycopsid miospores most typically found in mudstones, including Lycospora torquifer and higher than normal abundances of Granasporites medius. In the transition from clastic rocks of the Folsomville Member to the upper bench of coal, miospores of 'ecotonal' lycopsids (Paralycopodites) reach their peak abundance, pteridosperms dominate megafossil assemblages and inertinite levels are relatively high. At higher levels of the upper bench of coal, vitrinite levels are higher and miospore assemblages are dominated by lycopsid miospores typical of coal swamps (Lycospora granulata, L. pusilla). The presence of conodonts in coalballs in the upper bench of coal and spirorbid worms in the split indicate that the paleoswamp may have received some marine or brackish water influence. Higher than normal salinity levels may explain the vegetational changes observed in the upper bench of coal near the Leslie Cemetery paleochannel.
|Number of pages||40|
|Journal||International Journal of Coal Geology|
|State||Published - Jan 1995|
Bibliographical noteFunding Information:
We thank the AMAX, Peabody, Old Ben and Solar Sources Coal Companies for allowing us access to working mines. Tom L. Phillips, Nelson Shaffer and John Nelson provided field assistance and much useful discussion. ACS undertook this work while on sabbatical leave in the Laboratory of Tom L. Phillips, who is thanked. Faith Fiene provided field assistance and mineralogic studies. We thank Mark Barnhill, Marc Bustin, C. Blaine Cecil, Walter Hasenmueller, Robert M. Kosanke, Rob Stamm, Christopher Wnuk and an anonymous reviewer for helpful comments on the manuscript. The research was supported in part by a Geological Society of America Research Grant to DAW, grants to ACS from the Royal Society of London and the Central Research Fund of the University of London, and National Science Foundation Grant 83-13094 to Tom L. Phillips. We thank James Ferrigno, National Museum of Natural History, for providing photographs of the plant compression fossils and Tom Servais and Mike Bosco, U.S. Geological Survey, for providing computer-generated figures. W.A. DiMichele notes the support of the Evolution of Terrestrial Ecosystem program of the National Museum of Natural History, from which this is publication number 10.
ASJC Scopus subject areas
- Fuel Technology
- Economic Geology