SPORES IN STRATA OF LATE PENNSYLVANIAN 

 CYCLOTHEMS IN THE ILLINOIS BASIN 



R. A. Peppers 



ABSTRACT 



Vertical variation in relative abundance and variety of small spore genera and species 

 that might be useful for correlation of strata was examined in various marine and non- 

 marine units of cyclothems in the McLeansboro Group (late Pennsylvanian) of Illinois 

 and in equivalent strata of western Kentucky. Sixty-one samples of various lithologies 

 were macerated from two fairly complete sections of the Trivoli Cyclothem in the Modesto 

 Formation of Illinois, from the Fithian Cyclothem in the Bond Formation of Illinois, and 

 from several cyclothems in the Henshaw Formation of Kentucky. Forty of the samples 

 yielded identifiable spores. Nearly all shale samples contained some spores, but most 

 limestones, underclays, and siltstones below underclays were either barren of plant micro- 

 fossils or contained relatively few, poorly preserved spores. 



Of the 200 species of spores recorded, 33 are formally described as new. New taxa 

 include 15 species of Punctatisporites, three of Granulatisporites , three of Laevigatosporites, 

 two of Calamospora, and one species each of Raistrickia, Cadiospora, Crassispora, Secari- 

 sporites, Ahrensisporites, Indospora, Lundbladispora, Trivolites, Latipulvinites, and 

 Columinisporites. The last three, which are new genera, are formally described. Sixty-five 

 additional spore taxa are described briefly, but specific names are not assigned to them 

 because not enough specimens of each taxon were found. Scolecodonts and three forms of 

 hystrichospheres also are noted. Centonites, a new microfossil genus of uncertain origin, 

 is described. 



A comparison of several cyclothems revealed no consistent pattern in the vertical 

 succession of small spore assemblages. In both sections of the Trivoli Cyclothem and in 

 one of the cyclothems of the Henshaw Formation, the abundance of Florinites increased 

 upward in strata above the coal. Florinites and a small number of other bladder-equipped 

 pollen grains found in several shales overlying coal possibly were dispersed from the 

 upland flora, which was relatively undisturbed during invasion of the sea and the re- 

 sultant drowning of the coal swamp flora. 



Some shales and siltstones yielded small numbers of Densosporites and Lycospora 

 above the vertical ranges indicated for these fossils in North America by previous spore 

 studies of coals. Such occurrences probably resulted from the reworking of older sedi- 

 ments. Densosporites produced by small herbaceous lycopods also could have survived in 

 non-coal-swamp environments after the Densosporites-hearing lycopods of the coal swamps 

 became extinct. 



Within a single cyclothem, most spore genera range through a wide variety of 

 lithologies, but their relative abundance may vary considerably. Some spqre species persist 

 through several successive lithologies in a single cyclothem, but others are more erratic 

 in distribution. 



