Geophysical Characteristics of Shale Domes


Seismic		Shale domes are readily located by conventional reflection seismic methods. They may be distinguished from salt domes 1) by conventional Dt analysis because the interval velocities in shale are lower than in salt and 2) by the crestal sag as suggested in the seismic line shown below.
Gravity		Gravity surveys are less definitive because newly emplaced shale generally have low densities but older shale bodies which have dewatered are usually much more dense than the surrounding rocks. Thus, shale domes may cause gravity minima, gravity maxima or no discernible anomalies. The diagram below demonstrates this phenomena. The cylinders represent shale diapirs.
Table of Contents		Other Effects on Shale Structure