A Deterministic Evaluation of eismic Fidelity using Velocity Modeling ...

sedimentation is the second major event, a depositional hiatus producing an unconformity
updip from the Vinton Dome area. Continuation of the lower Frio deposition after a
marine transgression and deepening of marine environment was the third event. A
bathyal environment along the continental slope is an interpretation of the primarily shale
upper portion of the lower Frio (Figure 16). Uplift, folding, and erosion resulted in the
formation of the pre-Hackberry unconformity that marks the fourth major stage of the
Vicksberg-Frio-Anahuac events along the northwestern Gulf of Mexico Basin. Possibly
related to this stage is the movement of salt resulting in the uplift and folding.
The pre-Hackberry unconformity represents a depositional hiatus making downcutting of
channels into the pre-lower Hackberry possible and the truncation of these beds over
local salt domes (Figure 17). There are two mechanisms used to explain subcropping of
lower Frio and older sections interpreted from well data. One is due to domal uplift
resulting in non-deposition of Vicksburg through middle Frio and the other is uplift and
truncation following deposition of the base of the middle Frio. Either mechanism
indicates that closely spaced salt masses became loaded by contrasting sediment densities
that caused passive diapirism to produce salt domes. Contemporaneous to the passive
diapirism was the formation of rim synclines and interdomal withdrawl basins as the salt
pushed basinward, creating depressions in the pre-Hackberry surface (Figure 18) (LeVie,
1986). These topographic differences of interdomal ponds and salt domes can account
for the presence submarine canyons formed by turbidity currents channeled through the
interdomal areas (LeVie, 1986). Erosion renewed after tilting of the unconformity
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