Geometric analysis of faulted rollovers: Contrasting styles of extensional growth folding in the Gulf of Mexico and Offshore Trinidad
- Amoco Corp., Houston, TX (United States)
Rapid sedimentation rates combined with the presences of seaward-dipping detachment levels in both the U.S. Gulf of Mexico (GOM) and the Columbus Basin (Offshore Trinidad) have facilitated the development of large extensional growth faults and their associated hanging-wall rollover folds. While detachment in the GOM is often associated with salt and/or overpresurred shale, shale is believed to be responsible for detachment and translation of large structural blocks within the Columbus Basin. Although, gravity-driven extension seems to be the primary mechanism driving structural development in both regions, the detailed structural geometries and deformational mechanisms present seem to be quite different. In the Columbus Basin, extensional rollovers are generally dominated by the presence of pervasive synthetic faults. Restoration of these structures suggests that these synthetic faults are accomodating the bulk hanging-wall deformation as the hanging-wall slides basinwards above an underlying listric fault surface. This synthetic simple shear deformation is not typically observed in Gulf of Mexico rollovers. In contrast, although synthetic faults are present, often observed in Gulf of Mexico rollovers. In contrast, although synthetic faults are present, often spatially associated with the master growth fault, antithetic or mixed antithetic/synthetic faulting dominates the crest of the structures. An antithetic simple shear deformation is borne out by simple geometric modeling and restoration. The synthetic faulting seem in Trinidadian rollovers to be influenced by the presence of important vertical pressure seals (major unconformities) that may act as internal detachment levels within the larger folds. Synthetic faults are often observed to sole or die downwards into these intervals. Generally, lateral closure of rollover anticlines in the GOM is controlled by the underlying scoop-like shape of the major listric growth faults.
- OSTI ID:
- 425426
- Report Number(s):
- CONF-960527--
- Country of Publication:
- United States
- Language:
- English
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