About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)


Journal of Sedimentary Research
Vol. 85 (2015), No. 5. (May), Pages 544-561
Research Articles

Quantification of a Distributive Fluvial System: The Salt Wash DFS of the Morrison Formation, SW U.S.A.

Amanda Owen, Gary J. Nichols, Adrian J. Hartley, Gary S. Weissmann, Louis A. Scuderi


Recent analysis of modern aggradational continental sedimentary basins reveals that sedimentation patterns are dominated by distributive fluvial systems (DFSs). The Salt Wash Member of the Late Jurassic Morrison Formation has previously been described as a fan-shaped fluvial system. This study characterizes facies variations across the Salt Wash DFS to quantitatively test predicted trends in conceptual DFS models. Notable proximal-to-distal trends include a change in total thickness of the fluvial succession from 174 m to 40 m, and an average grain size from coarse sand to silt, while the percentage of sand decreased from 70% in the proximal region to 8% in the distal region. The proportion of amalgamated channel-belt deposits decreased from 67% to 0%, while floodplain facies and lacustrine deposits increase (38% to 94% and 0.1% to 7% respectively). A downstream decrease in average channel-belt thickness (15 m to 3.8 m, from thickest to thinnest) and average story thickness (7.7 m to 2.3 m, from thickest to thinnest) is also recorded. Significant downstream changes in deposit architecture were also noted, with proximal regions dominated by stacked channel-belt deposits with a high degree of amalgamation. Distal deposits are dominated by floodplain muds and sheet sandstones and sparse ribbon channels, with little to no amalgamation of channel deposits. This study provides quantified information for an ancient DFSs with the aim of providing a dataset that can be used for objective comparison between different DFSs, as well as providing numerical data to aid resource exploration and modelling efforts.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24