Thermochronological and Geochronological Constraints on Late Cretaceous Unroofing and Proximal Sedimentation in the Sevier Orogenic Belt, Utah

Abstract

A source‐to‐sink analysis incorporating geochronometric and thermochronometric data from the Sevier fold‐thrust belt (SFTB) and proximal synorogenic strata of the Canyon Range Conglomerate (CRC) and Indianola Group (IG) provides new insights into orogenic exhumation, erosional unroofing, and the interplay between thrusting and coarse clastic deposition in the Cretaceous Cordilleran foreland basin of western North America. Zircon (U‐Th)/He ages from the Pavant and Nebo thrust sheets record significant Cenomanian cooling indicative of synchronous exhumation and thrusting along a large segment of the SFTB in central and northern Utah. Detrital zircon (U‐Th)/He (DZHe) ages indistinguishable from depositional ages from the Cenomanian Dakota Formation and lower CRC also record rapid unroofing of the SFTB and synchronous deposition. DZHe data from wedge‐top deposits of the CRC record two significant unroofing episodes: Albo‐Cenomanian exhumation of the Pavant thrust and progressive unroofing of the Canyon Range culmination. For the IG, the presence of Paleozoic DZHe ages along with Paleozoic‐Mesozoic DZ U‐Pb ages in the Cenomanian Sanpete Formation suggests derivation from Paleozoic to Jurassic strata exhumed in the frontal Pavant and Nebo thrust sheets. After the Cenomanian episode of rapid exhumation, proximal foredeep strata recorded a widespread DZ provenance shift in the Turonian. Short DZHe lag time values from Campanian CRC and IG deposits reveal rapid exhumation of the SFTB during the Campanian. The synchroneity of major shortening and Campanian and Cenomanian changes in foreland basin architecture and provenance supports models proposing that active shortening in the fold‐thrust belt coincides with coarse clastic influx in foreland basins.

The Role of Shortening in the Sevier Hinterland Within the U.S. Cordilleran Retroarc Thrust System: Insights From the Cretaceous Newark Canyon Formation in Central Nevada

“…Numbers correspond to supporting studies compiled on Table 1. Timing constraints for the East Sierran thrust belt (from Walker et al., 1995; Dunne & Walker, 1993; 2004), Luning‐Fencemaker thrust belt (summarized in Wyld, 2002), and the western and eastern thrust systems of the Sevier fold‐thrust belt are shown (from DeCelles & Coogan, 2006; Giallorenzo et al., 2018; Pujols et al., 2020; Yonkee et al., 2019); see text for discussion.…”

“…After ∼85 Ma, deformation migrated eastward into smaller‐scale foreland thrust systems that were active until ∼66 Ma (e.g., Lawton et al., 1993). In west‐central Utah (∼39°N), the western thrust system is represented by the Canyon Range and Pavant thrusts (which both carry Neoproterozoic‐Paleozoic rocks that were deposited to the west of the Wasatch Hingeline; DeCelles & Coogan, 2006), which were emplaced between ∼130–125 Ma (Pujols et al., 2020) and ∼93 Ma (DeCelles & Coogan, 2006) (Figure 14b). The eastern thrust system at this latitude consists of the Pavant footwall duplex, Paxton thrust, and Gunnison thrust, which were emplaced between ∼93 and ∼66 Ma (DeCelles & Coogan, 2006).…”

Zircon (U-Th)/(He-Pb) double-dating constraints on the interplay between thrust deformation and foreland basin architecture, Sevier foreland basin, Utah

“…Progressive unroofing of the Canyon Range, Pavant, and Nebo thrust sheets is also reflected in the DZ U-Pb and DZ He age trends recorded in the Indianola Group (Pujols et al, 2020). The Sanpete and Funk Valley Formations (lower Indianola Group) are characterized by sediment mixing of Neoproterozoic to Mesozoic strata, likely sourced from Neoproterozoic-Paleozoic sections in the Canyon Range thrust sheet and Mesozoic-Paleozoic strata in the easternmost Pavant and Nebo thrust sheets (Pujols et al, 2020). Moving up section into the Sixmile Canyon Formation, the DZ U-Pb age spectra become dominated by Neoproterozoic-Paleozoic DZ U-Pb ages in response to unroofing of Neoproterozoic-Paleozoic strata of the Canyon Range and potentially the Sheeprock and Tintic thrust sheets in central and northern Utah, respectively (Pujols et al, 2020).…”

“…Progressive unroofing of the Canyon Range, Pavant, and Nebo thrust sheets is also reflected in the DZ U-Pb and DZ He age trends recorded in the Indianola Group (Pujols et al, 2020). The Sanpete and Funk Valley Formations (lower Indianola Group) are characterized by sediment mixing of Neoproterozoic to Mesozoic strata, likely sourced from Neoproterozoic-Paleozoic sections in the Canyon Range thrust sheet and Mesozoic-Paleozoic strata in the easternmost Pavant and Nebo thrust sheets (Pujols et al, 2020).…”

Detrital zircon provenance record of the Zagros mountain building from the Neotethys obduction to the Arabia-Eurasia collision, NW Zagros fold-thrust belt, Kurdistan region of Iraq

“…The zircon (U-Th)/He ages were acquired following the methodology described in Wolfe and Stockli (2010). For detailed laboratory and data reduction processes please refer to Thomson et al (2017), Xu et al (2017), and Pujols et al (2020).…”