Abstract
Speleogenesis in carbonate bedrock occurs when water, acidified by CO2 , dissolves calcium carbonate (CaCO3) in rocks to form voids and dissolutional conduits. The near surface geology of the Water Sinks area is dominated by Silurian–Devonian limestones, accommodating numerous karst features including sinkholes, caves, and springs. Groundwater flow and cave development in the area is thought to be guided primarily by geologic structure (folds, bedding, and joints) and low-permeability layers. In this study, we use electrical resistivity methods to detect and characterize conduits and water flow paths in the subsurface. We collect dipole-dipole and Schlumberger array data along seven transects at various locations throughout the study area using a multielectrode geoelectrical imaging setup. We then compute inverted resistivity models for the subsurface (from dipole-dipole, Schlumberger, and merged datasets) with varying smoothness and noise thresholds using a 2D inversion modeling software. The inverted resistivity sections confirm known void spaces near major caves in the area, while also revealing previously unknown void spaces, including evidence of a previously unknown maze cave complex. We interpret the resistivity sections within the framework of the local geology to enhance the existing narrative of the speleogenetic history and karst hydrogeology of the Water Sinks study area, with future studies and expeditions focusing on the newfound cave system.
DOI
https://doi.org/10.5038/9781967518012.1021
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Constraining the Groundwater Pathways Driving Cave Formation in the Water Sinks Area in Highland County, Virginia, USA Using Electrical Resistivity Imaging
Speleogenesis in carbonate bedrock occurs when water, acidified by CO2 , dissolves calcium carbonate (CaCO3) in rocks to form voids and dissolutional conduits. The near surface geology of the Water Sinks area is dominated by Silurian–Devonian limestones, accommodating numerous karst features including sinkholes, caves, and springs. Groundwater flow and cave development in the area is thought to be guided primarily by geologic structure (folds, bedding, and joints) and low-permeability layers. In this study, we use electrical resistivity methods to detect and characterize conduits and water flow paths in the subsurface. We collect dipole-dipole and Schlumberger array data along seven transects at various locations throughout the study area using a multielectrode geoelectrical imaging setup. We then compute inverted resistivity models for the subsurface (from dipole-dipole, Schlumberger, and merged datasets) with varying smoothness and noise thresholds using a 2D inversion modeling software. The inverted resistivity sections confirm known void spaces near major caves in the area, while also revealing previously unknown void spaces, including evidence of a previously unknown maze cave complex. We interpret the resistivity sections within the framework of the local geology to enhance the existing narrative of the speleogenetic history and karst hydrogeology of the Water Sinks study area, with future studies and expeditions focusing on the newfound cave system.