Paper No. 8
Presentation Time: 4:00 PM
CHRONO-GEOMORPHIC MAPPING OF DOLINE FIELD EVOLUTION: POTENTIAL FOR DATING KARST TERRANES
Recent work has shown that initiation and evolution of doline populations can be modeled with a family of functions known as logistic growth functions. As an outgrowth of this work, new insights provide an opportunity to map in chronologic context the spatial evolution of a large doline population from the Western Highland Rim(TN) and contiguous Pennyroyal Plain(KY). Initiation and evolution of a doline population begin with parent dolines developing at sites of maximum systematic joint-intersection loci. Parent doline initiation provides the geomorphic and hydrogeologic conditions conducive to initiation and development of one or more daughter dolines clustered around each parent doline within its respective karst- influence field. Daughter dolines develop within the karst- influence field of a parent doline at sites where fewer systematic joints intersect. Doline initiation and enlargement are density dependent mechanisms and involve a negative feedback mechanism in which number and size of daughter dolines reflect this dependency.
Parent doline initiation rates increased as the Cumberland River incised its valley and attendant ground-water hydraulic gradients increased with valley relief. Daughter doline initiation rates increased as the distance to the Cumberland River valley wall decreased, reflecting increased local hydraulic gradients. Both doline subpopulations (parent and daughter) reached steady-state conditions rates of valley incision decreased and fluvial steady-state equilibrium occurred.
Limited radiometric dating and logistic growth analysis of parent and daughter doline subpopulations allow chronospatial mapping of karst terrane evolution using isochrons based on parent and daughter doline initiation rates and estimated times to reach steady-state conditions.