Journal of Sedimentary Research, 2013, v. 83, 606–636 Research Article DOI: 10.2110/jsr.2013.50 POLYGENETIC HISTORY OF PALEOSOLS IN MIDDLE–UPPER PENNSYLVANIAN CYCLOTHEMS OF THE ILLINOIS BASIN, U.S.A.: PART I. CHARACTERIZATION OF PALEOSOL TYPES AND INTERPRETATION OF PEDOGENIC PROCESSES 1 1 2 2 NICHOLAS A. ROSENAU, NEIL J. TABOR, SCOTT D. ELRICK, AND W. JOHN NELSON 1Roy M. Huffington Department of Earth Sciences, Southern Methodist University, 3225 Daniel Avenue, Dallas, Texas 75275-0395, U.S.A. 2Illinois State Geological Survey, 615 East Peabody, Champaign, Illinois 61820, U.S.A. e-mail:
[email protected] ABSTRACT: The morphology, mineralogy, and stratigraphic and lateral distribution of paleosols in Pennsylvanian (Moscovian–Gzhelian; Atokan–Virgilian) mixed marine and terrestrial coal-bearing strata (i.e., cyclothems) in the Illinois basin (IB) are presented in order to determine the dominant pedogenic processes within a cyclic sedimentary depositional framework. Paleosol morphologies range from weakly developed horizons with evidence of rooting and little to no pedogenic structure, to horizons with well-developed pedogenic slickensides, angular blocky structure, and carbonate nodules and tubules. The majority of paleosols in strata from the basin interior preserve (1) low chroma (gley) colors, (2) identifiable fossil plant organic matter that increases in abundance upward in the profiles toward the interpreted paleo-surface, and (3) calcite, sphaerosiderite, and pyrite cements and nodules. In contrast, paleosols in strata from the northern