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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 and Louis A. Scuderi
Quantification of a distributive fluvial system; the Salt Wash DFS of the Morrison Formation, SW U.S.A.
Journal of Sedimentary Research (May 2015) 85 (5): 544-561

Abstract

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.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 85
Serial Issue: 5
Title: Quantification of a distributive fluvial system; the Salt Wash DFS of the Morrison Formation, SW U.S.A.
Affiliation: University of London, Department of Earth Sciences, London, United Kingdom
Pages: 544-561
Published: 20150520
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 95
Accession Number: 2015-058295
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., sketch map
N37°00'00" - N41°00'00", W109°00'00" - W102°00'00"
N26°00'00" - N37°00'00", W114°45'00" - W93°30'00"
N37°00'00" - N42°00'00", W114°04'60" - W109°04'60"
Secondary Affiliation: University of Aberdeen, GBR, United KingdomUniversity of New Mexico, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201526
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