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ABSTRACT: Distribution of Organic Sulfur in Macerals of the Herrin Coal Under Marine and Transitional to Nonmarine Shales

HARVEY, RICHARD D., and ILHAM DEMIR, Illinois State Geological Survey, Champaign, IL

Both total sulfur and the organic form of sulfur are known from bulk analyses to be more concentrated in whole coal that underlies marine strata than in those under nonmarine strata. However, the amounts of organic sulfur in the various macerals of coal overlain by these two different types of strata are not known. Our goal was to determine if the relative sulfur concentrations observed for whole coal are also maintained in each of the maceral types. Spot analyses of organic sulfur in macerals were determined by SEM-EDX methods in many layers of the Herrin (No. 6) Coal at two nearby sites in southern Illinois. One set of samples represents 2.5 m of coal at a site where the overlying strata are black shale (Anna Shale) deposited in a marine environment. The other sample set represents .3 m of coal where the overlying strata are gray shale (Energy Shale) deposited in an environment that was transitional to nonmarine.

The results show that the organic sulfur contents are distinctly variable within a given maceral type and in different layers of the seam. With minor exceptions, average values of each type are significantly higher in macerals overlain by the marine shale than in those overlain by the transitional shale. Furthermore, the mean organic sulfur contents are highest in sporinite, intermediate in vitrinite and resinite, and lowest in fusinite in nearly every layer of the seam at both sites. These results support the theory that sulfur levels above about 1 to 2% in the coal were introduced during the late stage of peat formation when it was saturated with marine (sulfur-bearing) water during one or more transgressive events.

 

AAPG Search and Discovery Article #91013©1992 AAPG Eastern Section Meeting, Champaign, Illinois, September 20-22, 1992 (2009)