GEOPHYSICAL IMAGING OF THE FRANKLINTON DIKE SWARM

The Franklinton Dike Swarm (FDS) traverses the northcentral portion of North Carolina and intrudes the western edge of the Rolesville Batholith, a portion of the Rolesville/Raleigh Terrain. A 5-kilometer long segment of the N12W trending mafic dike swarm was mapped using a proton-precession magnetometer (PPM) and a Very Low Frequency (VLF) meter. Both tools imaged the magnetite-rich intrusive; however, the VLF provided a dip angle to the dike based upon a statistical algorithm. Further, the VLF data set provided a more precise surface location for these dikes than the PPM.

The FDS consists of 2 members that are separated by approximately 300 meters. The western dike swarm consists of numerous en echelon dikes; whereas the eastern dike mapped as a single 5-kilometer long lineament. Both members have near vertical attitudes with high-angle dip to the northeast. The age ot the dike swarm is Mesozoic, however, no cross-cutting relationships offered any insite as to the age of the FDS. Groundwater tends to exploit dike swarms thus the FDS can have an impact on the shallow groundwater regime in northcentral North Carolina.