Sevier orogeny

[8] In southwestern Utah, Sevier thrusts may have remained active until the Eocene,[7][6] while Laramide deformation began in the Late Cretaceous.

[8] In general the Sevier orogeny defines an older, more western compressional event that took advantage of weak bedding planes in overlying Paleozoic and Mesozoic sedimentary rock.

As the crust was shortened, pressure was transferred eastward along the weak sedimentary layers, producing “thin-skinned” thrust faults that generally get younger to the east.

[9] These thin skinned thrusts moved late Precambrian to Mesozoic age rock of the Cordilleran passive margin east.

They are comparable because the younger Laramide faults and structures were a geometric response to the shallow dipping Sevier thrusts.

[4] The Sevier belt left behind many distinctive geologic features in the Wyoming and Utah region, namely recesses and salients.

In the Sevier-Laramide orogenic events evidence for interior plate deformation includes folds, cleavage and joint fabrics, distorted fossils, persistent faulting, and calcite twinning.

[17] Metamorphism due to the crustal heating and thickening is prevalent between 90 and 70 Ma in the present Great Basin region.

[12] The Basin and Range Province extending across Nevada, into western Utah, and south into Mexico now consists of N-S normal faulting due to crustal extension.

If these normal faults show any extension in late Eocene to early Miocene, this could be evidence the Sevier orogenic event collapsing after deactivation.

[10] Thickening of the crust due to Sevier and Laramide faulting is thought to have led to current Basin and Range extension throughout the Cenozoic.

[12] The results were interpreted to support the Charleston transverse zone forming during the Sevier orogeny to accommodate geometric changes along strike of the thrusts.

[10] Results also support the Uinta recess forming during the Sevier orogeny due to similar geometric crustal accommodation.

Displacement on Sevier aged thrust faults caused the shaping of the curvature of the Uinta recess prior to uplift of the Uinta/Cottonwood arch.

This correlation provides evidence that the Sevier thrust belt was a result of compression moving eastward through the North American plate.

[11] Thinning of the Cordilleran has previously been thought to be evidence and reason for flat subduction in the Sevier and Laramide orogenic events.

Differential stress magnitudes determined from calcite twinning showed a decreasing trend exponentially toward the craton.

Sevier shortening has been recorded throughout much of the western United States as far east as Minnesota in the Cretaceous Greenhorn Limestone as preserved by calcite twinning.

The E-W shortening shown in calcite twinning of the Sevier is parallel to today's principal stresses in the western interior of the North American plate.

Volcanic activity can be observed at modern subduction zones, (such as along the west coast of South America) like the one that caused the Sevier Orogeny.

[1] Volcanic centers migrated generally eastward during the progression of the Sevier[1] and the transition to Laramide deformation, and by the late Cretaceous volcanism related to Farallon Plate subduction could be found as far east as the Colorado Mineral Belt, east of the leading edge of the Sevier fold and thrust belt.

Location of the Sevier Fold and Thrust Belt (highlighted in red). After Yonkee and Weil (2015). [ 1 ]
Map from U.S.G.S. showing the Basin and Range Province in the United States. Basin and Range includes the western portion of Utah, essentially all of Nevada - the central heart of the Great Basin itself - bits of southern Oregon and Idaho, southern Arizona, New Mexico and far west Texas, and the eastern fringe and southeastern desert region of California. It also extends into Baja California and other areas of northwestern Mexico.
This is a diagram showing how transverse zones often connect thrust faults in a fold and thrust belt.
This is a cross section of a typical ocean–continent subduction zone, showing the major geologic features that accompanied the Sevier orogeny.