Surficial Evidence of Tectonic Activity and Erosion Rates, Palestine, Keechi, and Oakwood Salt Domes, East Texas

Surficial geologic investigations at Palestine, Keechi, and Oakwood salt domes have provided information necessary for evaluating these domes as nuclear waste repositories. Diapir growth uplifted sediments to form domes and created complex radial faulting. Cretaceous rocks crop out at Palestine and Keechi Domes, whereas only Eocene Claiborne sediments are exposed over Oakwood Dome. Annular drainage patterns at Oakwood and Palestine Domes reflect the domal structure. Holocene deposition is occurring over the center of all three domes in topographic depressions; these topographic lows suggest that minor subsidence has occurred. At Palestine Dome, recent sinkholes caused by abandoned brining operations indicate that the dome is unsuitable as a repository site. All three diapirs are located within the central Trinity River drainage basin. Depths to salt at Palestine, Keechi, and Oakwood Domes are 37 m, 133 m, and 351 m, respectively. Quaternary terraces of the Trinity River reveal no evidence of warping caused by domal or regional uplift. The average denudation rate in East Texas is calculated to be 8.85 cm/1,000 yr. Incision by the Trinity River into the bedrock is 15 m beneath the present floodplain near the domes. Geomorphic studies of denudation and river entrenchment in the Trinity River drainage basin indicate that it is unlikely that Oakwood or Keechi Domes would be breached by erosion during the life of a potential repository.