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The AAPG/Datapages Combined Publications Database

AAPG Special Volumes

Abstract


Pub. Id: A155 (1986)

First Page: 281

Last Page: 307

Book Title: M 41: Paleotectonics and Sedimentation in the Rocky Mountain Region, United States

Article/Chapter: Thrusting and Synorogenic Sedimentation in Central Utah: Part III. Middle Rocky Mountains

Subject Group: Structure, Tectonics, Paleostructure

Spec. Pub. Type: Memoir

Pub. Year: 1986

Author(s): A. Villien (1), R. M. Kligfield

Abstract:

New paleontologic data on detrital lithostratigraphic units in central Utah, which are inferred to represent the synorogenic products of compressive deformation, provide a basis for dating the times of transport of each of several thrust sheets. The thrust belt in central Utah can be divided geometrically into four major thrust systems from west to east: the Canyon Range, Pavant, Gunnison, and Wasatch thrust systems. Biostratigraphic correlations and constraints imposed by the geometry of thrust systems suggest the following ages for thrusting events: late Albian for the Pavant 1 thrust, late Santonian-early Campanian for the Pavant 2 thrust, middle to late Campanian for the late Canyon Range thrust, late Maestrichtian for the Gunnison thrust system, and late Paleocene fo the Wasatch thrust system.

In the hinterland, a combination of structural, stratigraphic, and chronologic evidence suggests that shortening was accommodated by the development of a Previous HitbackwardNext Hit-breaking thrust sequence: Pavant 1 thrust, Pavant 2 thrust, and (late) Canyon thrust. This led to the formation of successive overlapping unconformities of late Cenomanian, early to middle Campanian, and late Campanian age. In the foreland, the Gunnison thrust system has a ramp-flat geometry; a series of blind, splay, imbricate faults are associated with a major ramp beneath Sevier and Sanpete valleys. Late Cretaceous and Paleocene unconformities coincide with the development of an imbricate fan structure, which was subsequently deformed during late Paleocene time by formation of a deeper duplex structure within the Wasatch hrust system. Associated back thrusts accommodated shortening toward the surface at the west side of the Wasatch Plateau.

Tectonic loading produced a foreland basin and a correlative forebulge located east of the toes of the major thrust sheets. The times of superimposed thrusting phases, when compared with eustatic episodes recorded in the Cretaceous seaway, indicate that episodes of continental tectonism were approximately synchronous with eustatic rises in central Utah. Overall structural zonation and sedimentation patterns in central Utah can be correlated in a general sense with similar features in the Wyoming thrust belt salient farther north, but some significant differences are that some of the compressive stresses in central Utah were accommodated by such Previous HitbackwardTop-breaking thrusts as the Pavant 2 fault.

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