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

The Cretaceous Cordilleran foreland basin strata exposed in the Book Cliffs of eastern Utah and western Colorado have motivated important concepts linking thrust belt deformation and foreland basin evolution largely on the basis of sequence stratigraphy, stratal architecture, and sediment provenance evolution. However, these methods and approaches generally cannot provide critical insights into the temporal or causal linkages between foreland basin architecture and thrust belt deformation. This is in part due to discrepancies in age resolution and lack of evidence with which to directly couple sediment supply and basin-fill evolution to thrust belt unroofing. New detrital zircon (DZ) geothermochronometric data from Upper Cretaceous proximal to distal foreland basin strata in the Book Cliffs provide new quantitative insights into sediment origin and dispersal in relation to thrust belt deformation and exhu­mation. Detailed DZ U-Pb and (U-Th)/He double dating reveals that the Book Cliffs foredeep detritus was mainly delivered by transverse routing systems from two major sources: (1) Neoproterozoic and Lower Paleozoic strata from the central Utah Sevier thrust belt, and (2) Permian–Jurassic and synorogenic Cretaceous strata recycled from the frontal part of the thrust belt. A dramatic increase in Sierran magmatic arc and Yavapai-Mazatzal DZ U-Pb ages, as well as Paleozoic DZ He ages, in the deeper marine portions of the foreland basin points to axial fluvial and littoral sediment input from the Sierran magmatic arc and Mogollon highland sources. Both transverse and axial transport sys­tems acted contemporaneously during eastward propagation of the Late Cretaceous thrust belt. DZ He depositional lag time estimates reveal three distinct exhumation pulses in the Sevier thrust belt in the Cenomanian and Campanian. The exhumation pulses correlate with shifts in sediment prove­nance, dispersal style, and progradation rates in the foreland basin. These new data support conceptual models that temporally and causally link accelerated exhumation and unroofing in the thrust belt to increases in sediment supply and rapid clastic progradation in the foreland basin.

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

<div>Table S1 contains sample locations and formation names. Tables S2 and S3 contain the isotopic data for all samples DZ U-Pb (Table S2) and DZHe ages (Table S3). Table S4a-b shows the K‐S test p and D values between all Book Cliffs DZ U‐Pb samples before and after excluding volcanic grains. Table S4c shows K‐S test p and D values between all the DZ U‐Pb age populations from the Book Cliffs (this study), Sevier fold-and-thrust belt, and proximal strata (Pujols et al., 2020).<br></div>

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

<div>Table S1 contains sample locations and formation names. Tables S2 and S3 contain the isotopic data for all samples DZ U-Pb (Table S2) and DZHe ages (Table S3). Table S4a-b shows the K‐S test p and D values between all Book Cliffs DZ U‐Pb samples before and after excluding volcanic grains. Table S4c shows K‐S test p and D values between all the DZ U‐Pb age populations from the Book Cliffs (this study), Sevier fold-and-thrust belt, and proximal strata (Pujols et al., 2020).<br></div>