Element Geochemistry of Cherokee Group Coals ( middle Pennsylvanian) from South-Central and Southeastern Iowa: Technical Paper No. 5, 1984

(1984) Element Geochemistry of Cherokee Group Coals ( middle Pennsylvanian) from South-Central and Southeastern Iowa: Technical Paper No. 5, 1984. University of Iowa

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Abstract

Middle Pennsylvanian Cherokee Group coals from southcentral and southeastern Iowa are typical highsulfur, high-ash coals. These coals have an arithmetic mean sulfur content of S.R percent and a mean ash content of 15.9 percent. Apparent rank for most samples is high-volatile C bituminous coal. The relatively high contents of sulfur and 23 other elements in Iowa Cherokee Group coals are related to near neutral pH conditions (6-8) in the depositional and early diagenetic environments, and to postdepositional epigenetic sphalerite/calcite/pyrite/ kaolinite/barite mineralization. Changes from an aluminosilicate- to a sulfide-alement association for U, Mo, Cr, and V, and an increase in element content for U, Mo, Cr, V, Na, Mg, and K in stratigraphically higher coals are thought to be related to differences in depositional environments of the coal-associated rocks, which change from predominantly terrestrial in the lower Cherokee Group, to predominantly marine in the upper part of the Upper Cherokee Group.