QUANTIFYING PSEUDOKARST HYDROGEOLOGICAL CONTROLS IN A PERMIAN SANDSTONE SILTSTONE AQUIFER, OKLAHOMA

The removal of the subsurface aquifer occurs from both dissolution and piping of aquifer material resulting in features that can be observed in both karst and soil landscapes. Pseduokarst represents the intermediate zone of the weathering spectrum where dissolution (karst) and piping (soil gully) processes represent its end members. Between the endmember sections, an interplay between the weathering processes of dissolution and piping result in the formation of karst-like (pseudokarst) landforms.

Much of the focus on pseudokarst formation has been centered around the dissolution of quartz arenite sandstone aquifers. As quartz sediment is relatively insoluble, a focus on the process of dissolution limits the understanding of pseudokarst formation to only one side of the weathering spectrum. This field study defined the hydrogeologic parameters required to form pseudokarst in the weakly bonded sandstone of the Garber Wellington group in Stillwater, Oklahoma. Analysis of hydrological, geophysical and land survey data showed the importance of vertical permeability variations in fine grained siltstone units and clay residual controlling the flowpaths which allow dissolution and piping from the system. The results demonstrate the importance of fine grain units and residual sediments as hydrogeologic controls of pseudokarst development.