Stratigraphic Architecture and Lithofacies of High-Frequency Deltaic Sequences: Virtual Outcrop Analysis of the Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale, South-Central Utah, USA
Christopher R. Fielding
Date of this Version
Horton, C.J., 2017, Stratigraphic Architecture and Lithofacies of High-Frequency Deltaic Sequences: Virtual Outcrop Analysis of the Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale, South-Central Utah, USA [MS thesis], Lincoln, University of Nebraska-Lincoln, 99 p.
Sequence stratigraphic models for low-accommodation settings are not well-formulated and lack documented examples illustrating lithofacies stratal stacking pattern complexities. Presented herein is a detailed stratigraphic analysis of the Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale Formation; a fluvial-deltaic succession that primarily accumulated under forced-regressive, falling stage systems tracts during decreasing accommodation. The small (4 km2) study area is located at the connecting point of a 67 km long, depositional strike-oriented and a 30 km long, depositional-dip transect within the western-limb of the Henry Mountains Syncline. Detailed outcrop sections and digital Light Detection and Ranging (LiDAR) derived Virtual Outcrop Models (VOM) analysis are used to define and characterize the stratigraphic architecture. Correlation of all bodies within the stratigraphic interval display the anatomy of a prograding deltaic system composed of crudely coarsening-upward cycles. This paper focuses on the ‘Critical Interval’, athick, cyclic succession of entrenched distributary channels, reworked delta plain, and transgressive shoreface sandstones that lies above a regionally extensive sequence boundary and separates the lower and upper Ferron members. The moderately incised (<5 >m), relatively small (150-300 m wide) channel bodies and locally preserved delta plain deposits are interpreted to record two individual sea-level cycles. The incomplete sequences and the facies were influenced by marine-processes and the low-amplitude and high-frequency nature of sea-level fluctuations that characterize Ferron Sandstone Member accumulation. This study provides detailed facies characterization and illustrations of the stratigraphic architecture with implications for deltaic sequences deposited in a low accommodation setting.
Adviser: Christopher R. Fielding