PALYNOLOGY AND PETROGRAPHY OF A 

 MIDDLE DEVONIAN COAL IN ILLINOIS 



R. A. Peppers and H. H. Damberger 



ABSTRACT 



Samples of a carbonaceous sediment, varying from 

 coal to coaly shale and less than 1 to 2 inches thick, were 

 obtained from three diamond drill cores of the Wapsipini- 

 con Limestone in McLean and northern DeWitt Counties , 

 Illinois. This is the only known occurrence of Devonian 

 coal in Illinois. 



Microscopic examination of polished samples in 

 reflected light reveals that the coal is only partly lamina- 

 ted. The nonlaminated, less coaly portion may represent 

 reworked material. Spores account for about 12 percent of 

 the laminated coal and only 3 percent of the nonlaminated 

 portion. The rest of the coal consists of the maceral vit- 

 rinite. Mineral matter includes pyrite, limestone, quartz, 

 dolomite, calcite, and very fine-grained argillaceous car- 

 bonates. 



The macerated coal constituents consist of small, 

 irregularly shaped plant fragments, unornamented circular 

 bodies that are perhaps algal in origin, and plant spores. 

 Of the 28 species and 13 genera of small spores that were 

 identified, 6 species are named and described as new. The 

 most frequently encountered spore genera, in decreasing a - 

 bundance, are Apicu lat a s porite s , Retusotriletes , Spino - 

 zonotriletes , Ac anthotrilete s , Lycospora , Emphanispor - 

 ites, and Rhabdosporites . Plant microfossils of marine ori- 

 gin — Tasmanites, Leiosphaeridia , and Veryhachium — were 

 also observed in the macerations. The spore assemblage 

 does not resemble any previously described Devonian as- 

 semblage. 



The coal was deposited along the northern flank of 

 the Sangamon Arch, which was essentially standing above 

 sea level during most of the Devonian Period. Most of the 



1 



