Chatanooga shale investigations along the Sequatchie anticline of Tennessee and Alabama

Abstract

In 1953 the Chattanooga shale in the Sequatchie anticline was tested for its uranium content by seven diamond drill cores. Concurrent with the drilling, geologic field work was done to determine the distribution, thickness, and structural setting of the shale. The results of this investigation indicate that the Chattanooga shale in the Sequatchie Valley has a higher uranium content than the shale along the Eastern Highland Rim but is more folded and faulted. For the purposes of these investigations the anticline is roughly divisible into three subequal parts, designated as northern, central, and southern. In the northern part the Gassaway member of the Chattanoooga shale is 13 to 21 feet thick and probably contains from 0.0060 to 0.0076 percent uranium. An unusual thickness of the phosphatic interval in one core suggests some duplication of strata. Similar deformation could cause erratic distirbution of the more uraniferous beds. In the central part of the anticline the Dowelltown member of the shale is overlapped by the Gassaway member so that only the latter is present in the central and southern parts of the anticline. The Gassaway is thin and poorly exposed between the State line and Guntersville, Ala., but southward it thickens again to about 40 feet near Blountsville. In the southern part the uranium content of the shale, as determined from three drill cores, is surprisingly low when compared with analyses of 1952 outcrop samples from three sides of the area. On the basis of available data, 20 feet of shale in the area between hole AL-66, 3 miles southwest of Blountsville, and locality 4G-1 at Blount Springs may contain between 0.0057 and 0.0070 percent uranium, but more drilling would have to be done to check the higher figure, which is based on outcrop samples. Data are too sparse to permit reliable estimates of grade and tonnage. More geologic work and drilling are needed to block out the most favorable areas.