ABSTRACT 



The alga Botryococcus was observed in coal macerations 

 from twelve coal beds in the Tradewater Formation 

 (Lower and lower Middle Pennsylvanian) in the Illinois 

 Basin. In Illinois, Botryococcus occurs in the Bell, Del- 

 wood, Lewisport, New Burnside, and Reynoldsburg 

 Coal Beds, in the Brush, Hermon, Murphysboro, and 

 Tarter Coal Members, and in an unnamed coal bed; in 

 Indiana it occurs in the St. Meinrad, Lower Block, and 

 Buffaloville Coal Members and an unnamed coal bed; 

 and in Kentucky it occurs in the Bancroft(?), Bell, Breck- 

 inridge, Lewisport, and Delwood coal beds. Some 

 names identify the same coal, whose designation may 

 vary by state. 



Although Botryococcus is rare at most of the 43 sam- 

 ple sites where it was found, it is abundant at two sites in 

 the Lewisport and at one site each in the Reynoldsburg, 

 New Burnside, Delwood, and Brush Coals and Breckin- 

 ridge coal bed. It is common at two sites in the Delwood 

 and one site in the Tarter and Mariah Hill Coals. Botryo- 

 coccus has been found more commonly (14 sites) in the 

 Delwood than in any other coal. A distribution pattern 

 of Botryococcus abundance is not apparent because of 

 the small number of sites of each of the coals containing 

 the alga. Although Botryococcus is still a living genus, it 

 has not been observed in coals in the Illinois Basin 

 above the lower Middle Pennsylvanian, even though 

 hundreds of samples of the most extensive coal seams 

 in the basin, which occur in the upper Middle Pennsyl- 

 vanian, have been examined. 



The Lewisport coal and overlying and underlying 

 strata at one sample site were macerated to compare the 

 abundance of Botryococcus with the lithology and com- 

 position of the spore assemblages. The alga is most 

 abundant in the coal and overlying coaly shale in which 

 Lycospora, produced by large lycopod trees, is most 

 abundant. Botryococcus is least abundant in the under- 



day and gray shale that overlies the coaly shale in 

 which fern spores are most abundant; Granasporites 

 medius, representing the arborescent lycopods Dia- 

 phorodendron and Synchysidendron, is most abundant in 

 the gray shale. Sphenopsid spores are abundant in the 

 coal, underclay, and some intervals of gray shale over- 

 lying the coal. As with the Lewisport, coal beds in 

 which Botryococcus is abundant also contain an abun- 

 dance of Lycospora. 



Petrographic analyses of selected samples indicate 

 an average of 0.5 to 3.2 volume percent of Botryococcus 

 in coals bearing this type of alginite (liptinite group of 

 macerals). The Botryococcus occurs in irregularly 

 shaped colonies. These colonies are embedded in a 

 matrix of desmocollinite vitrinite along with small 

 sporinite {Lycospora) and to a lesser extent other macer- 

 als that are common in coals of bituminous rank. Up to 

 60% or more of some ultra-thin coal layers consists of 

 algae colonies. Such layers or bands are properly 

 termed torbanite. Microscopical (optical and scanning 

 electron microscope) studies suggest that the colonies 

 of Botryococcus have not been permanently compressed 

 from their original morphology during subsequent 

 coalification. 



Because Botryococcus lived in fresh to brackish 

 water, the association of abundant algae and Lycospora 

 reinforces evidence from earlier paleobotanical studies 

 that coal swamp lycopod trees grew in the parts of the 

 swamps that were very wet and periodically flooded. 



A knowledge of the distribution of abundant 

 Botryococcus may aid in outlining lower-sulfur content 

 areas within coal beds. High-sulfur coal is more closely 

 associated with coal swamps that were near shore and 

 drowned by marine water than with swamps that were 

 higher on the delta plain and drowned by freshwater 

 stream deposits. 



INTRODUCTION 



Algae in coal in the Illinois Basin were first reported by 

 Kosanke in 1951. He compared the fossil algae in the 

 top several inches of the Tarter Coal Member from an 

 outcrop in Fulton County with the living alga Botryococ- 

 cus. We have subsequently observed Botryococcus in 

 several other coal beds in the Illinois Basin during rou- 

 tine palynological analyses. In most samples, algae are 

 rare, but in several samples they are abundant. 



One of the purposes of this study was to identify 

 the extent and stratigraphic occurrence of the coals that 

 contain Botryococcus and to determine whether there is 

 a pattern in the distribution and abundance of the alga. 

 A related goal was to determine whether the alga's 

 presence could be used in biostratigraphic correlations. 

 The study also sought to provide clues concerning the 

 environments of deposition of the coals, which could 

 aid in identifying coal with relatively low sulfur con- 

 tent. Finally, we wanted to determine the alga's distri- 



bution in coal and to characterize its morphology in 

 coal after compaction. 



Palynology of the Lewisport coal and overlying 

 and underlying strata in an outcrop in Union County, 

 Kentucky, was studied in detail to determine the rela- 

 tion of spore abundance to Botryococcus abundance. 

 This relationship clarifies the paleoecology of ancient 

 Pennsylvanian peat swamp plants because the ecology 

 of living Botryococcus is known. In addition, spore 

 analysis of several coal samples of different ages that 

 contain abundant Botryococcus indicates the kinds of 

 vascular plants most common in the coal swamps that 

 supported the growth of algae. 



Petrographic analyses of several coal samples con- 

 taining abundant Botryococcus were made, including a 

 scanning electron microscope (SEM) study that charac- 

 terized Botryococcus morphology. Petrography also re- 

 vealed the relative abundance and relationship of 



