Glaciation and saline-freshwater mixing as a possible cause of cave formation in the eastern midcontinent region of the United States: A conceptual model

Abstract

We present a hypothesis for the formation of caves and associated karst features near the southern margins of the Illinois, Michigan, and Appalachian basins. Spatial and temporal relations among intracratonic basins, karstic terrain, and continental glaciation suggest that Pleistocene glaciation may have initiated the discharge of saline waters from the margins of these basins. Glaciation-induced discharge of saline waters could result from the consolidation of sediments due to the overlying pressure of glacial ice, and flushing of underlying aquifers as a result of bottom melting in recharge areas of basic aquifers. The upward migration of basin-derived saline waters into near-surface aquifers would result in the mixing of saline waters with infiltrating glacial meltwater and meteoric water. The development of a vertically restricted zone of mixing of saline and fresh water in limestone aquifers would result in the dissolution of limestone; this mechanism could be responsible for the formation, or at least the initiation of, some caves and associated karst features in the midcontinent region.