AN INTRODUCTION TO THE STRATIGRAPHIC PALYNOLOGY OF THE CHEROKEE GROUP (PENNSYLVANIAN) COALS OF IOWA

R.L. Ravn


Iowa Geological Survey
Technical Paper No. 6, 1979, 117 p.

ABSTRACT


The Cherokee Group of southern Iowa consists of a complex sequence of sediments including numerous coals. Lateral relationships of the coal seams are unclear on the basis of lithologic evidence alone. Preliminary palynological studies suggested the need for detailed examination of vertical variability of miospore populations within selected coals seams as a supplement to routine channel sample analyses for biostratigraphic correlation. A thick coal of uncertain stratigraphic relations, designated CP-19-4, was sampled to test the utility of detailed miospore profile evaluation..

CP-19-4 yielded a diverse, well-preserved miospore population with marked vertical variation, appearing to relate closely to gross petrologic variability of coal lithotypes. Three major miospore associations were distinguished, dividing the seam into nearly equal sub-units; - a lower interval, dominated by gymnospermous prepollen and pollen grains, designated the Florinites interval; a middle interval, characterized by an abundance of lycopsid-related spores, designated the Densosporites-Crassispora interval; and an upper interval, dominated by the arborescent lycopsid spore Lycospora granulata, designated the Lycospora interval. The overall miospore assemblage is equivalent in age to that of the Pople Creek Coal of the Illinois Basin.

A paleoecologic reconstruction of the coal swamp depositional history is suggested on the basis of the miospore profile. The distribution of specific miospores within the seam indicates a series of depositional events, evidence of which may be traceable laterally and useful for correlation. A comparison with coals obtained from other cores illustrates the utility of the approach in complex stratigraphic sections.

Formal taxonomic information is provided for 171 miospore species; eight new genera, 13 new species and 4 new combinations are proposed. Additionally, diagnoses of 3 species are formally emended, and 1 new name is proposed to replace a previous name found to be a junior homonym under provisions of the International Code of Botanical Nomenclature (1978). New taxonomic names proposed in this report are: Leiotriletes guennelii nom. nov. emend., Calamospora nebulosa sp. nov., Adelisporites multiplicatus gen. et sp. nov., Lophotriletes confertus sp. nov., Cuneisporites rigidus gen. et sp. nov., Tetanisporites granulatus gen. et sp. nov., Apiculatisporis saetiger (Peppers) comb. nov., Crassispora annulata sp. nov., Cirratriradites reticulatus sp. nov., Thysanites densus gen. et sp. nov., Vestispora luminata sp. nov., Diaphanospora parvigracila (Peppers) comb. nov., Potonieisporites solidus sp. nov., Wilsonites circularis (Guennel) comb. nov., Pseudoillinites diversiformis (Kosanke) gen. nov. et comb. nov. emend., Peppersites ellipticus gen. et sp. nov., Wappellites variabilis gen. et sp. nov., and Phillipsites tenuis gen. et sp. nov. Reinschospora triangularis (Kosanke, 1950) is emended.


Reference:

Kosanke, R.M., 1950, Pennsylvanian spores of Illinois and their use in correlation: Illinois Geological Survey Bulletin 74, 128 p.