Geophysical and Geologic Characteristics of Fracture Zones in the Carbonate Floridan Aquifer

摘要

Fracture traces in the carbonate bedrock of west-central Florida can have very distinctive geophysical responses. The responses over the fracture zones are associated with increased depth and thickness of the geoelectric layers, microgravity lows, resistivity lows, and conductivity highs. Closely-spaced vertical electrical soundings yield the most information on the stratigraphy and geometry of the fracture zone and aid in interpretation of the character of the fractured limestone. The tri-potential method detected isolated fractures not directly associated with the principal fracture zone. The geologic character of the two fracture zones is very different. Although photolinears often represent vertical fracture zones, many hydrogeologically important fractures may exist that are not expressed on aerial photos or the land surface.