| Summary |
This study will ascertain the joint system that is conducive to the hydrothermal discharge at Jefferson Springs of the Warm Springs Township, Bath County, Virginia, by the use of fracture and geophysical analysis. The temperatures of Jefferson Springs are, 35.2°C at 11.7 1/sec at the Ladies pool and 35.7°C at 28.4 1/sec at the Men's pool. The use of resistivity data will help resolve the anisotropic nature of the rock material of the hydrothermal springs. The lineament study uses ground measurements, digital elevation models, and LANDSAT 5 images that shows joint structures (a plumbing system) conducive to hydrothermal discharge. The use of gravity, ground magnetic profiling, and aeromagnetic survey data will determine the presence and association of possible igneous intrusive bodies with the hydrothermal spring at Jefferson Springs. Fracture data collected at outcrops within watergaps, exposed outcrops of anticlines, mountain ridges, and mountain passes (watergaps) along with processed LANDSAT 5 imagery of the greater Warm Springs area show lineations that support the northwest and northeast trend determined by resistivity. Analysis of gravity data shows that northwest trending gradient is a basement feature of the Martinsburg Trough and that the northeast trending grain is due to the carbonates and sandstones of the Warm Springs anticline. Northeast and northwest trending fractures (seen in LANDSAT 5, DEM images, and determined from resistivity) govern the hydrothermal springs (Jefferson Springs) of Warm Springs, Bath County, Virginia. The "plumbing system" determines the flow paths of the hydrothermal water (fracture planes that form prismatic, cubic, and trigonal blocks) where that system provides higher vertical hydraulic conductivity than the horizontal hydraulic conductivity. The hydrothermal area of Warm Springs has an apparent resistivity of 300-500 ohm-meter in a northwesterly direction and a 1600-3100 ohm-meter in the northeasterly direction. The lower apparent resistivity in the northwest direction shows that current flow prefers this direction due to increased fracture porosity. Magnetic anomalies of the ground magnetic profile in this study match some of the anomalies in the aeromagnetic data. The magnetic anomalies may be due to plutons of unknown composition. Highland County (the county just north of Bath County) has exposed basaltic and alkaline andesitic dikes of Eocene age about 30 miles north. The builders of a hydro-electric dam about 20 miles to the northwest in Bath County reported andesite dikes of Eocene age. The gravity and magnetic anomalies indicate that there may be bodies of rock that are different in density then the sedimentary strata and contain ferro-magnetic minerals. If these are unexposed plutons, then the joint system must reach basement rock (~8 km), thus giving the hydrothermal water more than enough vertical distance to achieve their temperatures. |
