--> --> Megaporosity Development within the Central Tennessee Basin: A Comparative Study of Karst in Middle-Upper Ordovician Strata

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Megaporosity Development within the Central Tennessee Basin: A Comparative Study of Karst in Middle-Upper Ordovician Strata

Abstract

Megaporosity occurs in outcrop in many locations along the Duck River through Central Tennessee within a variety of Ordovician age strata. Among these, Parsons Bend Cave is a rectilinear maze cave formed in Middle Ordovician limestone with a complex speleogenetic origin related to primary hypogene porosity development and secondary epigene overprinting coupled with the incision of the Duck River. The site provides the focus area for development of diagenetic model for large-scale porosity development within the Nashville Group of the Central Tennessee Basin. This karst feature is located on the edge of the East Highland Rim Escarpment and the Cumberland Plateau and is part of a larger speleogenetic province that hosts isolated megaporosity development throughout the region.

Using the Parson's Bend Cave as a point of comparison to other karst features in the area, a diagenetic model has been developed and is begin refined through correlation with other known karst porosity within the region. Data gathered from eight other cave features in the area, including geomorphic maps detailing spatial footprints of megaporosity development coupled with lithological characterization and geographic information system (GIS)-based spatial interpolation are providing insight into the speleogenetic evolution associated with the Duck River. This data includes variations in carbonate depositional environments and changes in lithology which are compared to analyze the sedimentological controls favorable for karst development.

The macroconduits that these features represent are of crucial importance in understanding fluid flow within the region as well as developing models for similar karst development within more deeply buried strata that may be associated with hydrocarbon reservoirs.