Internal Structure of the Grand Saline Salt Dome, Van Zandt County, Texas

Since 1947, the Morton Salt Company’s Kleer mine in the Grand Saline salt dome has more than doubled in size. Balk’s mapping of the salt structures in the pre-1947 workings showed that (1) the layers of salt near the southeastern border of the dome dip steeply southeast and south, presumably parallel with the dome border. Elsewhere the layers form intricate systems of folds. (2) The axes of all folds plunge nearly vertically. (3) Anhydrite and halite are elongated parallel to the nearest fold axis. (4) The absence of any fractures, faults, cross-cutting salt layers, foreign inclusions, and brine indicates an undisturbed evolution of the deformation structure in a nearly homogeneous, layered salt mass. The present study [1959] includes the new workings and contains a composite map of Balk’s study and this one. In addition to confirming Balk’s conclusions, this study demonstrates that (1) the structure of this dome is not symmetrical; consequently, this dome probably rose as a series of spines. (2) Radical changes in strike of the trace of the axial planes at the mine levels occur along east-trending planes, which possibly represent zones of failure in the overburden. (3) Attenuation of folds is observed as the perimeter of the dome is approached. (4) Beds of giant salt crystals exhibit cleavage faces several feet on a side.