Discontinuity detection in Eocene sediments of east Texas: Employing a cesium magnetometer and a ground conductivity meter

A cesium magnetometer and a ground conductivity meter were used to detect geological discontinuities in the alternating sands and shales of the Eocene of east Texas. Survey locations were chosen across accessible faults from the Palestine Sheet. A total of six surveys were conducted in five separate locations. Three surveys were conducted along a northeast trending fault located in Nacogdoches County. The other three surveys were conducted along the eastward trending Mount Enterprise Fault Zone: one in Rusk County, two in Cherokee County.; Data were analyzed for abrupt changes in the earth's magnetic field and ground conductivity values. These variations occur when the geophysical instruments cross an abrupt lithologic change, like sand to shale. The cesium magnetometer detects the amounts of magnetically susceptible minerals in each lithology recording a magnetic signature across the discontinuity. This magnetic signature can then be interpreted as a fault. The ground conductivity meter detects the ability of the earth to conduct an electric current. Shale has a greater capacity to conduct electricity than sand; therefore, discontinuities can be detected when they occur between sands and shales.