Response of Soils and Soil Ecosystems to the Pennsylvanian–Permian Climate Transition in the Upper Fluvial Plain of the Dunkard Basin, Southeastern Ohio, USA

Abstract

Direct exposure of paleosols to the atmosphere during formation make them ideal for reconstructing paleoclimate. Paleosol and ichnofossil properties are dependently linked making it important to study them in tandem, to avoid errors in interpretation. Small scale studies (<1 km) yield high resolution data that can be used to assess allogenic processes through comparison of spatial and temporal trends. This study used field and laboratory analyses to gather data from Late Pennsylvanian to Early Permian Upper Monongahela and Lower Dunkard group paleosols on Ohio Route 33 in Meigs County, OH, USA. The physical and geochemical properties of the paleosols from the field sites indicate that channel migration was the primary control on paleosol formation in the study area, however, a clear climate signal was observed. The change in paleosol type and calculated mean annual precipitation (MAP) values indicate that the climate became more strongly seasonal and drier over the course of the Pennsylvanian-Permian transition with a temporary excursion to a more ever-wet climate with higher MAP, marked by the occurrence of the Waynesburg Coal at the Pennsylvanian-Permian boundary.

Analysis of climate and landscape change through the Pennsylvanian and Permian Monongahela and Dunkard Groups, Southeastern Ohio, USA

“…A transition to a more stable, seasonally dry environment then occurred through the rest of the Monongahela Group followed by seasonally wet conditions at the base to middle of the Lower Dunkard Group, with small scale fluctuations in between, before a switch to seasonally dry conditions at the top. These climatic trends generally agreed with local studies on correlative strata conducted by Hembree and Bowen (2017) and Hembree and Carnes (2018).…”

“…Hembree and Bowen's (2017) study of Upper Monongahela and Lower Dunkard group paleosols yielded an upward trend of decreasing mean annual precipitation (MAP) and increasing seasonality. This same transition was recognized by Hembree and Carnes (2018) in three Upper Monongahela and Lower Dunkard group outcrops. A third study conducted by Hembree and Blair (2016) on outcrops of the Washington Formation revealed thick, repeating successions of calcareous Vertisols characteristic of dry and seasonal conditions.…”

“…These small-scale lateral changes along the same horizon are clear examples of autogenic controls such as topography and proximity to active channels, on soil development (Aslan and Autin 1998;Kraus 1999). A study of the Monongahela Group on outcrops ~ 30 km south of this study area classified upper Monongahela Group paleosols as Vertisols with better-drained soil conditions (Hembree and Carnes 2018). These large-scale differences were attributed to regional variation in topography; the localities of Hembree and Carnes (2018) were on the upper fluvial plain, whereas localities in this study were on the lower fluvial plain (e.g., Martin 1998).…”

“…This study involved the investigation of short-term climate variability and related changes in terrestrial paleolandscapes of the Appalachian Basin during the Late Paleozoic climate transition through the study of paleosols and ichnofossils of the Monongahela and Lower Dunkard groups in southeastern Ohio. The Upper Pennsylvanian to Lower Permian Monongahela and Dunkard groups consist of fluvial and lacustrine sediments deposited during a transition from a largely wet-seasonal to dry-seasonal climate (Driese and Ober 2005;King 2008;Fedorko and Skema 2013;Montañez and Cecil 2013;Hembree and Carnes 2018). Several studies conducted in the western United States have utilized paleosols to investigate the Late Paleozoic climatic transition…”