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The several proposed models for the evolution of the Gulf of Mexico suggest different types of movement on the Mexia fault zone. One recent model suggests that the Yucatan Peninsula, in the Gulf at the beginning of the Jurassic, moved southwest to its present position during the Jurassic. This requires major right-lateral strike-slip movement with minor divergence in the vicinity of the Mexia fault zone. This fault zone trends north-south, consists of en echelon horsts and grabens striking about 30° east of the zone's trend, and was active from the Jurassic through the Eocene. The presence of the grabens, their orientation and en echelon arrangement, and the age of movement are all consistent with divergent strike-slip movement.
Hydrocarbons are generally produced from the basin side of the fault zone but have also been produced from fault traps within the grabens. Theoretical models, physical models, and field examples of strike-slip faults suggest the presence of en echelon anticlinal traps along the fault zone, and development of smaller antiformal structures where the en echelon grabens overlap. Such structures have not been described along the Mexia fault and may be important new structural plays, particularly for oil in the Smackover.
Post-Jurassic movement on the fault zone enhanced the structural relief of the grabens and probably was related to the mobilization of the Louann salts. Traps in the Cretaceous which produce most of the hydrocarbons are due to this later movement.
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