Mesozoic Tectonics of the Northern Wasatch Range, Utah

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Contribution to Book

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Field Guide to Geologic Excursions in Utah and Adjacent Areas of Nevada, Idaho, and Wyoming


JR Wilson


Utah Geological Survey

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The geometry and chronological development of regional structures in the Idaho-northern Utah-Wyoming fold and thrust belt are well constrained (Armstrong and Oriel, 1965; Royse and others, 1975; Dixon 1982; Lamerson, 1982; Wiltschko and Dorr, 1983; Oriel, 1986), making this an excellent area to study kinematics of thrust systems. Major thrusts cut up section to the east and transported Paleozoic and Mesozoic shelf and miogeoclinal strata relatively eastward above a regional decollement. Large-scale fault-bend and fault-propagation folds with concentric and kind geometries are associated with the thrusts. Synorogenic conglomerates record the successive emplacement of thrust sheets from west to east during the Mesozoic to early Tertiary Sevier orogeny. The fold and thrust belt forms a salient convex to the east, and is separated from thrust systems in central Utah by the Cottonwood and Uinta arches. The four major thrust systems exposed in northern Utah are from west to east the Willard, Ogden, Crawford, and Absaroka systems (Figs. 1 and 2). The frontal Hogsback thrust is exposed to the east in Wyoming. Basement rocks are absent in the frontal thrust sheets but are incorporated into thrust sheets in the Wasatch Range (Bell, 1951; Bruhn and Beck, 1981; Yonkee, 1990) and farther west (Snoke and Miller, 9188). The frontal thrust sheets are unmetamorphosed, but metamorphic grade locally reaches greenschist facies in the Wasatch Range (Yonkee, 1990), and increases in overall grade to the west (Snoke and Miller, 1988).


Originally published by the Utah Geological Survey. Limited preview available through remote link. This publication can be purchased through the publisher.