Fault trap regime

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Exploring for Oil and Gas Traps
Series Treatise in Petroleum Geology
Part Traps, trap types, and the petroleum system
Chapter Classification of exploration traps
Author Richard R. Vincelette, Edward A. Beaumont, Norman H. Foster
Link Web page
Store AAPG Store

Classes and definitions

There are four classes in the fault trap regime: normal fault, reverse fault, thrust fault, and wrench fault]. The outline below shows definitions and examples for the classes and subclasses of these traps or trapping elements.

Regime Class Subclass
Fault trap; Fault(s) forms part or all of the closure of the trap by sealing the reservoir either laterally and/or from the top (after Biddle and Wielchowsky[1]) Normal fault trap; One or more form all or part of lateral closure by sealing the reservoir. Tilted fault block; Block of rock bounded on one or more sides by normal faults. Rotation traps hydrocarbons along edges or in corners.
Horst; Block of rock bounded on all sides by normal faults.
Listric fault trap; All or part of closure formed by a fault whose plane curves downward and is concave upward.
Reverse fault trap; One or more faults form all or part of the closure by sealing the reservoir.
Thrust fault trap; Forms all or part of the closure by sealing the reservoir either laterally or from the top or bottom. Overthrust; Forms all or part of the closure by sealing the reservoir laterally.
Subthrust; Forms all or part of the closure by sealing the reservoir laterally or from the top.
Wrench fault trap; Forms all or part of the closure by sealing the reservoir laterally or from the top. Flower structure; Opposing reverse faults diverge upward, forming a fan or flower cross section pattern. Develop along wrench fault zones.

Families

Based on the genesis of the bounding faults, traps classified as fault traps can be divided into tectonic and nontectonic superfamilies. The outline below presents examples of trap families for several common fault traps. Similar trap families and subfamilies can be defined for most fault traps when the genesis of the trap is understood fully.

Regime Class Subclass Superfamily Family Subfamily Variety
Fault traps Normal faults Tilted fault block Tectonic; Normal fault, resulting from deformation by tectonic processes, forms all or part of the closure. Extensional; Fault, resulting from extensional deformation, forms all or part of the closure. Rift basin
Basin and range
Growth fault
Reverse faults Thrust faults Tectonic; Thrust fault, resulting from tectonic deformation by tectonic processes, forms all or part of the closure. Compressional; Fault, resulting from tectonic compressional deformation, forms all or part of the closure. Regional thrust belt
Foreland fold fault
Forearc basin
Wrench faults Subclass: Flower structures Superfamily: Tectonic; Normal fault, resulting from tectonic deformation by tectonic processes, forms all or part of the closure. Transpressional; Fault, resulting from tectonic transpressional deformation, forms all or part of the closure. Regional wrench system Inverted
Normal faults Nontectonic; Result from deformation by nontectonic processes such as uplift by intrusion or diapirism, differential compaction, salt withdrawal, salt solution, or meteoric impact. Extensional; Fault, resulting from nontectonic extensional deformation, forms all or part of the closure.
Family: Vertical uplift
Family: Vertical subsidence Subfamily: Salt solution
Subfamily: Salt withdrawal

See also

References

  1. Biddle, K. T., and C. C. Weilchowsky, 1994, Hydrocarbon traps, in L. B. Magoon and W. G. Dow, eds., The Petroleum System—from Source to Trap: AAPG Memoir 60, p. 219–235.

External links

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Fault trap regime
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