Neogene Flowstones of the Interior Low Plateau of Kentucky: Isotopic, Geochemical, and Petrographic Constraints on Near-Surface Hydrology and Climate

Flowstones exposed in quarries and caves within the Interior Low Plateau of Kentucky and neighboring regions preserve a record of near-surface hydrologic conditions that potentially spans the late Cenozoic pre-glacial and glacial periods. Detailed isotopic (δ ¹³C, δ ¹⁸O), geochemical (Mg, Sr, Ba, Fe, Mn), and petrographic analysis of flowstone sequences recovered from across the region may provide unique insight into the characteristics of climate shifts and may ultimately provide a temporal framework for regional climate change. Analytical results will be presented from several flowstones. Preliminary results from a flowstone preserved in a quarry at Rocky Knob, Casey County, Kentucky, indicate a dynamic range for both δ ¹⁸O (-7 to -2.5 ‰ V-PDB) and δ ¹³C (-13 to -7 ‰ V-PDB). Much of the 18 cm-thick flowstone records relatively wet conditions. The upper 3 cm of record preserve evaporation-dominated conditions, defined by trace-metal anomalies and significantly higher enrichment in isotopic compositions that are linearly correlated on a δ ¹⁸O vs. δ ¹³C plot. Linkages between trace-metal concentrations, crystal growth and morphology, and isotopic compositions will be explored and interpreted.