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