Palynology of the Springfield Coal of the Illinois Basin (Middle Pennsylvanian) with quantitative comparison of spore floras and coal-ball peats and implications for paleoecological studies
Willard, Debra Ann
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https://hdl.handle.net/2142/21544
Description
Title
Palynology of the Springfield Coal of the Illinois Basin (Middle Pennsylvanian) with quantitative comparison of spore floras and coal-ball peats and implications for paleoecological studies
Author(s)
Willard, Debra Ann
Issue Date
1990
Doctoral Committee Chair(s)
Phillips, T.L.
Department of Study
Plant Biology
Discipline
Plant Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Paleobotany
Palynology
Language
eng
Abstract
Spores and coal balls from profiles in the Springfield Coal of the Illinois Basin were analysed to determine how quantitative spore floras can be used in paleoecological interpretations of Pennsylvanian-age coals. Laterally extensive sampling of spore profiles also was designed to evaluate lateral and vertical floristic variation related to proximity to contemporaneous paleochannels, overbank deposits, and the coal margin. Thirteen spore profiles and three coal-ball profiles formed the basis for comparison of plant abundance in spore floras and in coal-ball peats. Tree-fern spores dominate the Springfield Coal spore flora, and lycopod spores are subdominant. In coal-ball peats, however, lycopods are the dominant biomass producers, and tree ferns usually rank second. The disparities in the two records were evaluated using R-values, ratios of the abundance of a taxon in the spore record to its abundance in coal balls. Although R-values are too variable among zones in profiles to accurately reconstruct the peat, they provide an estimate of how over- or under-represented each taxon is in the spore record. Generally, in the Springfield Coal, tree ferns are two to three times and lycopods one-half to three-fourths as abundant in the spore record as in the peat.
Spore profiles record different plant assemblages near paleochannels than are seen near the margin of the coal. Near the Galatia paleochannel, tree-fern spores are dominant, and four species (Laevigatosporites globosus, L. minimus, Punctatosporites minutus, and Thymospora pseudothiesseni) share dominance throughout the profile. Lycospora is subdominant. Near the coal margin, Thymospora pseudothiesseni dominates the lower three-fourths of the seam, and Laevigatosporites golobosus dominates the upper part of the seam. Lycospora is at its most abundant in the lower one-fourth of the coal, and Anacanthotriletes spinosus is abundant in the middle of the seam.
Even though spore abundance and peat biovolume do not correspond one-to-one, qualitative inferences about abundance and distribution of source plants can be derived from the spore record. Such comparison of the two records greatly extends our ability to make inferences about vegetational abundance in parts of the coal lacking coal balls and improves the resolution of paleoecological interpretations.
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