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 ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Characterizing an early stage <strong>of</strong> active piercement is the development <strong>of</strong> thick sediment<br />
covering the salt with a normal fault bounding one side <strong>of</strong> the rising salt. As the diapir<br />
rises an elongate anticline forms on the footwall side <strong>of</strong> the fault in response to the<br />
intruding salt. As the dome continues to grow radial faulting will develop on the footwall<br />
side with subparallel faulting on the hanging wall side (Figure 10). Passive piercement or<br />
down building is characterized by structures that result from salt withdrawal. A common<br />
feature forms from the dragging due to sediment compaction around the dome and as a<br />
result, the dip <strong>of</strong> sediment beds around passive domes tends to be less than seen around<br />
active domes. Passive domes tend to form circular geometries as they develop. Faults<br />
around passive domes radiate out at high angles and tend to be largest near the salt<br />
(Figure 11). Radial faults forming in this manner are a response to the relative uplift <strong>of</strong><br />
the sediments flanking the dome. Relative uplift is a response to the combination <strong>of</strong> the<br />
withdrawal <strong>of</strong> salt from its source layer, relative rise <strong>of</strong> the salt with respect to the source,<br />
and compaction and subsidence <strong>of</strong> sediments around the salt plug. Extensional stresses<br />
generated by the relative uplift around the circular plug tend to be oriented parallel to the<br />
salt sediment interface. Resulting faults that formed in response to this stress are<br />
perpendicular to this interface. If an active piercement structure phases into a passive<br />
piercement structure, the radial faults that develop in the passive phase generally have<br />
their footwalls toward the withdrawal flank that developed during the active phase<br />
(Nelson, 1991).<br />
20