THE PETROGRAPHIC CONTROLS ON GYPSUM KARST SPELEOGENESIS IN SOUTHCENTRAL KANSAS

The Permian Blaine Formation is known as a significant evaporite karst unit in Oklahoma and as a major fresh water aquifer in Texas; however, there have been limited documented karst studies in Kansas. The physiographic region of southcentral Kansas is colloquially known as the Red Hills, or the Gypsum Hills, due to the gypsum-capped buttes and mesas and the underlying iron-oxide-coated siliciclastics. Previous work in southcentral Kansas has compared lithologies from core and outcrop to determine the effects of late-stage dissolution and that the correlation of stratigraphic units were problematic. Late-stage near-surface dissolution of evaporites along carbonate contacts may provide insight into the geomorphology of the region.

Karst features from two properties in southcentral Kansas include caves, sinkholes, springs, losing streams, and other surficial features. Caves have been hypothesized to form along the Cedar Springs Dolomite, which is found at the geologic contact between the Medicine Lodge Gypsum and the Flowerpot Shale. This study further refines the premise that caves form along the Cedar Springs Dolomite, specifically investigating the nature of the lithologic variations of this subunit.

Samples were collected from outcrops and cave passages. Elevations of samples were recorded by a handheld GPS unit for use in a relational geodatabase. These elevations help determine if samples are from the Cedar Springs Dolomite or if the samples are from other subunits within the Flowerpot Shale. Petrographic observations revealed varying lithologies ranging from dolomicrites to peldolomicrite/oodolomicrites. Future work will continue to refine the stratigraphic control on karst development on these properties to develop a larger regional model for karstification.