10 



In correlation studies of the Illinois Basin, because of the wide variation in compo- 

 sition of spore assemblages through short stratigraphic intervals, the relative abundance 

 of small spore genera and species in coal appears to be of more value than their abundance 

 in other lithologies. However, if careful consideration is given to type of lithology, deposi- 

 tion of older reworked strata, and factors related to spore dispersal, spore assemblages of 

 non-coal lithologies may prove useful in correlating strata in areas where coals pinch out, 

 are poorly developed, or are essentially barren of spores, and where spore assemblages 

 from two or more coals are not easily differentiated. 



INTRODUCTION 



Plant microfossil assemblages from Penn- 

 sylvanian coals have been extensively re- 

 ported, but relatively little has been published 

 on the palynology of other Pennsylvanian 

 strata. This report is concerned with the in- 

 vestigation of small spores found in coal, ma- 

 rine, and nonmarine strata of several late 

 Pennsylvanian cyclothems within the Mc- 

 Leansboro Group of Illinois and equivalent 

 strata of western Kentucky (text fig. 1). A 

 fairly complete sequence of spore assemblages 

 was derived from strata of the Fithian Cy- 

 clothem in the Bond Formation and strata of 

 the Trivoli Cyclothem in the Modesto For- 

 mation (text fig. 2) . Samples of various lith- 

 ologies from at least three cyclothems in the 

 Henshaw Formation of western Kentucky 

 yielded spores at relatively widely spaced 

 vertical intervals. 



Henshow Formation 

 maceration 1122 



Fithian Cyclothem, 

 maceration 1170 



Trivoli Cyclothe 

 maceration 1128 



Trivoli Cyclothem, 

 mocerotion 1175 



FIG. 1 — Location of stratigraphic sections sampled 

 in Illinois and Kentucky. 



The first purpose of this study was to in- 

 vestigate the possibility of using plant spores 

 from lithologies other than coal for correla- 

 tion of Pennsylvanian strata in the Illinois 

 Basin where coals are absent or contain poor- 

 ly preserved spores. It was first necessary to 

 record and describe spores from a wide range 

 of lithologies from Pennsylvanian strata. As 

 most of the plant microfossils found in non- 

 coal sediments were produced by plants liv- 

 ing under paleoecologic conditions different 

 from those operating in the coal swamp 

 environment, palynologic investigations of 

 shales, limestones, siltstones, and underclays 

 were expected to reveal many spore genera 

 and species not previously reported from the 

 Illinois Basin. 



The second aim was to determine the rela- 

 tive abundance and variety of spore taxa 

 throughout several sequences of different 

 lithologies so that vertical ranges of spore 

 genera and species could be ascertained. Cer- 

 tain spore genera, such as Densosporites and 

 Lycospora, are known to be present in strata 

 above the limits determined for these genera 

 by coal macerations. 



A third purpose of this study was to de- 

 termine whether or not bisaccate gymno- 

 spermic pollen and prepollen grains, which 

 became such a conspicuous element of plant 

 microfossil assemblages in Permian strata, are 

 present in upper Pennsylvanian strata of the 

 Illinois Basin. Diamond drill core samples 

 from part of the Henshaw Formation of west- 

 ern Kentucky were selected for this purpose 

 because the sampled section is probably 

 younger than any other part of the Pennsyl- 

 vanian that has been described from the Illi- 

 nois Basin. 



Acknowledgments 



I am indebted to Dr. Robert M. Kosanke, 

 U. S. Geological Survey, for his advice on the 



