Balancing salt dome uplift and withdrawal basin subsidence in cross-section

Abstract

Idealized geometric models are presented for cases of cross-sections drawn perpendicular to elongate salt domes, where a two-dimensional model is adequate, and cross-sections drawn through the center of hemispherical salt domes, where a three-dimensional model is needed. Primary attention is devoted to domes during the salt pillow stage of uplift; however, a simple model is provided for the piercement stage as well. Mathematical relationships are derived between the cross-sectional area of the dome and the cross-sectional area of the associated withdrawal basin. Relationships are also derived relating non-dimensional dome uplift to non-dimensional basin subsidence. These relationships must be taken into account when constructing and restoring cross-sections of salt domes. Failure to do so can result in significant errors in estimating the amount of salt lost to dissolution. In addition, the relationships in this paper imply that there is a change in either salt dome height or withdrawal basin depth near the ends of an elongate dome, and predict that restored cross-sections of mini-basins developed on thick layers of salt typically will contain more salt than the present-day section.