Effects of contemporaneous orogenesis on sedimentation in the Late Cretaceous Western Interior Basin, northern Utah and southwestern Wyoming
Abstract
Northern Utah and southwestern Wyoming were subject to the effects of Sevier and Laramide-style deformation. Deformation from the Sevier Orogeny began in the Jurassic and resulted in the eastward propagation of thrust sheets and associated flexural foredeeps. Late Cretaceous Laramide tectonism resulted in tectonic partitioning of the Sevier foreland basin by exhumation of basement-cored uplifts within the precursor foreland. Lastly, long-wavelength dynamic subsidence is indicated by regional isopach patterns, which display an eastward shift in deposition, and major transgressions. The study interval from the Coniacian to Maastrichtian records a complex interplay of these deformational patterns.
Differential rates of subsidence and uplift throughout the Western Interior Basin have affected depositional environments and sediment routing patterns. The details of how variable uplift and subsidence affect sediment routing, however, are not fully understood. For example, the stratigraphic relationship between proximal wedge top sediments in the fold belt and the cyclic marine strata of the foreland is uncertain because of poor age control. This study uses outcrop lithofacies observations, paleocurrent measurements, chronology and provenance information from detrital zircons, and integrated outcrop/well log correlation combined with biostratigraphy to better define source to sink relationships. Detrital zircon data indicate varying sediment sources from proximal to distal parts of the basin, with distal samples demonstrating a provenance shift related to the transition from axial to transverse drainage pathways. We interpret this as due to Laramide partitioning. Three Maastrichtian uplifts have been identified based on thickening associated with flexure. Detrital zircon maximum depositional ages and biostratigraphy support that the proximal Hams Fork Conglomerate is deposited on the same Moxa Unconformity associated with the distal Ericson Formation fluvial sandstones. The Hams Fork, however, is ~2 m.y. younger than the upper Ericson. Therefore, the hiatus associated with the Moxa Unconformity extends into the early Maastrichtian.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP31C2302D
- Keywords:
-
- 1815 Erosion;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS;
- 8177 Tectonics and climatic interactions;
- TECTONOPHYSICS