Fault trap regime

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: 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, 1995).

Class: Normal fault trap

One or more form all or part of lateral closure by sealing the reservoir.

Subclass: Tilted fault block

Block of rock bounded on one or more sides by normal faults. Rotation traps hydrocarbons along edges or in corners.

Subclass: Horst

Block of rock bounded on all sides by normal faults.

Subclass: Listric fault trap

All or part of closure formed by a fault whose plane curves downward and is concave upward.

Class: Reverse fault trap

One or more faults form all or part of the closure by sealing the reservoir.

Class: Thrust fault trap

Forms all or part of the closure by sealing the reservoir either laterally or from the top or bottom.

Subclass: Overthrust

Forms all or part of the closure by sealing the reservoir laterally.

Subclass: Subthrust

Forms all or part of the closure by sealing the reservoir laterally or from the top.

Class: Wrench fault trap

Forms all or part of the closure by sealing the reservoir laterally or from the top.

Subclass: 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: Fault traps

Class: Normal faults

Subclass: Tilted fault block

Superfamily: Tectonic

Normal fault, resulting from deformation by tectonic processes, forms all or part of the closure.

Family: Extensional

Fault, resulting from extensional deformation, forms all or part of the closure.

Subfamily: Rift basin

Subfamily: Basin and range

Subfamily: Growth fault

Class: Reverse faults

Subclass: Thrust faults

Superfamily: Tectonic

Thrust fault, resulting from tectonic deformation by tectonic processes, forms all or part of the closure.

Family: Compressional

Fault, resulting from tectonic compressional deformation, forms all or part of the closure.

Subfamily: Regional thrust belt

Subfamily: Foreland fold fault

Subfamily: Forearc basin

Class: Wrench faults

Subclass: Flower structures

Superfamily: Tectonic

Normal fault, resulting from tectonic deformation by tectonic processes, forms all or part of the closure.

Family: Transpressional

Fault, resulting from tectonic transpressional deformation, forms all or part of the closure.

Subfamily: Regional wrench system

Variety: Inverted

Class: Normal faults

Superfamily: Nontectonic

Result from deformation by nontectonic processes such as uplift by intrusion or diapirism, differential compaction, salt withdrawal, salt solution, or meteoric impact.

Family: 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

• Structural trap system
• Fold trap regime
• Fracture traps
• Fracture trap regime

External links

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