FRACTURE MAP OF HARDIN COUNTY, KENTUCKY

New field mapping of joints combined with previously published joint and fault locations result in fracture orientations within map units for counties in Kentucky at 1:125,000-scale. These fracture maps can be used as a critical data source for hydrological, karst or geotechnical applications. Joint orientations were measured in 2009, and from 2022 to 2023, and are combined with joint and fault locations for Hardin County, Kentucky from 1:24,000-scale USGS geologic quadrangle maps that were published from 1962 to 1977. The geologic quadrangle maps for the county were digitized from 2002 to 2007. Field notes for the U.S. Geological Survey quadrangle maps were not available during the digitization process. Joint orientations were calculated by a DOS-based ArcInfo script written to determine the azimuth orientation when digitizing the “strike” of the joint symbol on the original geologic map.

The geology of Hardin County consists of Upper Devonian New Albany Shale overlain by Lower to Upper Mississippian-age sequences of limestone, dolomite, sandstone and shale. These units were juxtaposed by normal faulting after the Late Pennsylvanian. Dominant joint orientations for all map units trend 0-20, and 70-80 degrees, with minor orientations trending 40-50 and 290-310 degrees, with many joint orientations parallel to subparallel to nearby faults. Most joint orientations were measured in the Middle Mississippian St. Louis and Ste. Genevieve Limestones, which are the most extensive rock units in the study area. These joint orientations can be viewed online on the Kentucky Geological Survey map service (https://kgs.uky.edu/kygeode/geomap/).