Influence of paleotopography and superimposed pedogenic conditions on an Upper Pennsylvanian paleosol complex; Round Knob shale (Pittsburgh Reds), eastern Ohio

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5688165

Caudill, M R; Driese, S G; Mora, C I ^[1]; Fastovsky, D E ^[2]

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1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences
2. Univ. of Rhode Island, Kingston, RI (United States). Dept. of Geology

Vertically stacked paleosol profiles in the Round Knob (RK) shale are exposed in road cuts near Steubenville, OH. This unit overlies an interdistributary bay-fill type coarsening-upward sequence and is overlain by the Harlem coal. The RK characteristically possesses hackly soil-like structure and red coloration. The clay mineral assemblage consists of mixed-layer illite/smectite, illite, kaolinite, and chlorite. Immediately north of Steubenville and RK shale is dominated by strong gleying and gray-green coloration. Paleosols comprising the complex contain small slickensides, root races, complex carbonate nodules, and rhizoconcretions. Intersecting large curved slickensides and parallelepipeds are present and indicate that portions of the complex had a vertic affinity. The thickness of the paleosol complex varies laterally with changes in the lithology of subjacent strata. In general, the complex thins where it overlies fluvio-deltaic sandstone bodies and thickens away from them. This trend occurs at the expense of a locally-developed red basal unit, which appears to have occupied paleo-lows in the interchannel area. Vertical and subvertical, downward-branching root mottles are present throughout most of the complex and suggest the paleosols were once well-drained, or at least above the water table. The dominantly gleyed part of the paleosol complex records perching of the water table as the Harlem coal swamp encroached on the area. A zone of large, diffuse, subvertical gray-green mottles at the top of the basal red unit approximates the base of the water table. Arrival of the coal swamp brought with it a new set of soil forming conditions, which resulted in extensive leaching in the uppermost portion of the complex and led to partial removal of carbonate nodules to a depth of 1 meter. It is probable that many underclays formed from portions of precursor soils which were subsequently modified by pedogenic processes associated with superimposed coal swamps.

• OSTI ID: 5688165
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

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