(U-Th)/He and U-Pb double dating constraints on the interplay between thrust deformation and basin evolution

Despite several decades of evolving concepts for thrust belt mechanics and foreland basin evolution, an in-depth understanding of key process linkages and dynamic connectivity between foreland basins and thrust belts remain elusive. In particular, temporal aspects of thrust deformation, detrital provenance, flexural basin subsidence, and stratigraphic architecture, remain debated. This study provides an unprecedented systematic U-Pb and (U-Th)/He (He) detrital zircon (DZ) double dating provenance record for the classic Sevier fold-thrust belt (SFTB) and foreland basin in north-central Utah, to elucidate the temporal linkage between thrust deformation, hinterland unroofing and foreland basin sedimentation through improved isotopic provenance analysis. The zircon (U-Th)/(He-Pb) data in the SFTB and foreland basin allowed constraining distinct episodes of cooling, indicative of major Cenomanian and Campanian thrusting and denudation in the SFTB. The temporal synchronicity between deformation, exhumation and coarse clastic strata indicates that rapid hinterland deformation triggers episodes of major coarse clastic sedimentation and dispersal beyond the proximal foreland basin margin. Moreover, DZHe depositional lag time and DZ U-Pb provenance analyses at the one-myr chronostratigraphic resolution strongly suggest that discrepancies in stacking pattern, shoreline trajectory and progradation rates in the foreland basin can in fact be explained by distinct episodes of major hinterland exhumation. This high-density DZ data set, additionally establish an unequivocal temporal link between major retroarc shortening and voluminous arc magmatism, challenging current conceptual Cordilleran orogenic models that invoke temporal delays between retroarc shortening and voluminous arc magma generation. Both arc magmatic fluxes and retroarc shortening episodes appear to be driven by plate boundary convergence rates. Hence, this study proposes a new model where rate increases in subduction and/or overriding plate motion control both retroarc contraction and arc-magma cyclicity. Other aspects of this investigation explore the influenced of tectonics on continental-scale drainage reorganization in western North America and the Neuquén Basin, Argentina.
In summary, the integration of these zircon geo-thermochronometric data in the proper SFTB and foreland basin architectural context helped improve (1) conceptual models that relate temporal, thermal, and spatial aspects of thrust activity to sediment dispersal patterns and (2) shed light into the spatiotemporal feedbacks between upper-crustal deformation and convergent-margin magmatism in Cordilleran orogenic systems.