Assessment of the geological evidence for karst in the Rustler Formation at the WIPP site
John C. Lorenz
This paper assesses the geological evidence that has been offered for the presence of karst in the subsurface at the Waste Isolation Pilot Plant (WIPP) site. Most of this evidence has been used uncritically and out of context, and does not form a mutually supporting, scientifically defensible framework. Plausible evidence for subsurface dissolution is limited to the water bearing Magenta Member in drillhole WIPP-33. The remaining evidence is more readily interpreted as primary sedimentary features. Thinning and thickening of Rustler strata, and lateral lithologic variations from halite to mudstone, are primary depositional patterns related to lateral sedimentary facies changes across the WIPP site rather than evidence for postdepositional dissolution. Some of the evidence offered in support of dissolution is inherited from early interpretations made prior to the knowledge of modern evaporite depositional environments, and prior to the existence of definitive exposures of the rock in the WIPP shafts which show undissolved, primary depositional features. Holes drilled to investigate the subsurface strata at the sites of proposed sinkholes do not support karsting of the Rustler Formation. Extrapolation of the known karst features in Nash Draw eastward to the WIPP site is unwarranted.
- Lorenz, John C., 2006, Assessment of the geological evidence for karst in the Rustler Formation at the WIPP site, in: Caves and karst of southeastern New Mexico, Land, Lewis; Lueth, Virgil W.; Raatz, William; Boston, Penny; Love, David L., New Mexico Geological Society, Guidebook, 57th Field Conference, pp. 243-251.