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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typical <strong>of</strong> the shelf margin. Because <strong>of</strong> the strong extensional component <strong>of</strong> the faults and<br />
the movement <strong>of</strong> salt, the geometry as described by Nelson, 1991 (Figure 10) indicates<br />
that during Hackberry deposition Vinton Dome continued to form as an active diapir.<br />
Active diapirism could have resulted from the prograding margin pushing salt basinward<br />
initiating faulting. As the fault developed in response to salt movement, the salt pushed<br />
upward into the zone <strong>of</strong> weakness.<br />
Finally, the eighth and last event was the deposition <strong>of</strong> the remaining Frio and the early<br />
Anahuac (Paine, 1968). Upper Frio represents a regressive phase and lowering <strong>of</strong> sea<br />
level as is evident from the numerous sand sequences found in the upper Frio (Figure 23).<br />
Mapping <strong>of</strong> two <strong>of</strong> these sand units on 3-D PSTM (Figure 24) data indicate that a<br />
transition from active to passive diapirism as described by Nelson (1991), Figures 10 and<br />
11 began by the upper Frio. Anahuac sedimentation represents a late Oligocene<br />
transgression when the shelf margin was probably mud dominated (Figure 25) (Winker,<br />
1982). Structural interpretation <strong>of</strong> 3-D PSTM surface s<strong>eismic</strong> data (Figure 26) indicate<br />
that diapirism continued to be passive at the end <strong>of</strong> Anahuac deposition based on the<br />
interpretation <strong>of</strong> radial faulting and the lack <strong>of</strong> a major growth fault <strong>using</strong> Nelson’s model<br />
Figure 11.<br />
Miocene deposition shifted to a deltaic environment and back to a broad sandy strand<br />
plain (Figure 27) (Galloway et al., 2000). The early Miocene shelf-margin depocenter<br />
located in southwestern Louisiana remained active through the Quaternary and<br />
26