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	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)	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

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

External links

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