Thrust timing, growth of structural culminations, and synorogenic sedimentation in the type Sevier orogenic belt, western United States

Abstract

Most of the regional shortening in the type area of the Sevier orogenic belt in central Utah was accommodated by displacement on the Canyon Range (Neocomian-Aptian), Pavant (Aptian-Albian), Paxton (Cenomanian-Campanian), and Gunnison (late Campanian–Paleocene) thrust systems. Inception of each thrust system generated synorogenic sediment associated with frontal thrust-tip anticlines or triangle zones and older thrust sheets that were elevated above major ramps farther toward the hinterland. The Sevier culmination, a large antiformal duplex cored by crystalline basement rocks, developed during Paxton and Gunnison thrusting west of and structurally beneath the Canyon Range and Pavant thrusts. Growth of the Sevier culmination was coeval with reactivation of the Canyon Range and Pavant thrust systems and produced a second culmination in Proterozoic–Lower Cambrian rocks in the Canyon Range. These structural highs provided much of the sediment to the adjacent foreland basin from late Cenomanian to late Paleocene time, and may have helped to maintain critical taper in the thrust belt.