About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 68 (1984)

Issue: 4. (April)

First Page: 401

Last Page: 416

Title: Structural Geology of Stewart Peak Culmination, Idaho-Wyoming Thrust Belt

Author(s): David R. Lageson (2)

Article Type: Meeting abstract


A structural culmination is the highest point along a structural axis or fold system, away from which the folds plunge. Structural culminations are an important and predictable component of foreland fold-thrust belts, and are prime targets for oil and gas accumulations. The Stewart Peak culmination is a doubly plunging anticlinorium in the Absaroka thrust sheet of western Wyoming, located in the northern Salt River Range.

Major thrust faults in the Stewart Peak culmination comprise a large-scale duplex fault zone. The "roof fault" of the duplex is the Absaroka thrust, the "floor fault" is the basal or regional decollement, and the intervening Murphy and Firetrail thrusts are trailing-edge imbricate faults in the Darby plate that have locally uplifted and deformed the Absaroka into an asymmetric, breached anticlinorium or culmination. In addition, these major thrust faults subdivide the culmination into fault-bound structural horses, each with a characteristic style of deformation as a function of its stratigraphic and structural level in the duplex.

A recent exploratory test of the culmination provided data which suggest that the Absaroka thrust fault locally cuts downsection in the transport direction. This may be explained by initial folding and breaching of the Firetrail anticline, followed by main motion on the Absaroka thrust which overrode the fold.

The available data suggest that the Stewart Peak culmination is the result of (1) polyphase uplift or arching of the Absaroka thrust sheet by the Murphy and Firetrail thrust sheets, (2) lateral imbrication and ramping, and (3) arching of the Precambrian basement complex beneath the northern Salt River Range. In addition, a basic kinematic model of deformation applicable to structural culminations includes emplacement of an allochthonous mass over a parautochthonous substratum, closely followed by, or contemporaneous with, deformation and translation of the footwall section to produce a duplex fault zone that folds the overlying allochthon.

The Stewart Peak culmination bears many similarities in structural style and origin to polyphase folded-fault domes in the Canadian Rocky Mountains. Specifically, the Stewart Peak area is compared to the Savanna Creek and Moose Mountain culminations.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Protected Document: $10
Internal PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].