- Title
- Evolution of fluvial meander-belt deposits and implications for the completeness of the stratigraphic record
- Creator
- Durkin, Paul R.; Hubbard, Stephen M.; Holbrook, John; Boyd, Ron
- Relation
- Bulletin of the Geological Society of America Vol. 130, Issue 5-6, p. 721-739
- Publisher Link
- http://dx.doi.org/10.1130/B31699.1
- Publisher
- Geological Society of America
- Resource Type
- journal article
- Date
- 2018
- Description
- The fragmentary nature of the stratigraphic record is particularly evident with respect to fluvial deposits, which are characterized by a hierarchy of depositional units deposited over a wide range of time scales and sedimentation rates. We quantified stratigraphic completeness in meander-belt deposits through deducing the total area of bar sedimentation versus what is ultimately preserved in the depositional record, using area as a surrogate metric for sediment volume. Data sets were evaluated for a numerical model, the modern Mississippi River valley, and the Cretaceous McMurray Formation. In each data set, the evolutionary history of a series of meander-belt elements was discerned. Migrated area between successive reconstructed paleochannel positions was measured, representing: total area of net bar migration (MA), the area of bar preserved (PA), and percent of bar preserved (PA/MA), at the accretion package, bar, and meanderbelt scale. Results of our analysis show that the average preservation percent ranges from 27.3% to 67.8% for an accretion package, 35.0% to 85.1% for a bar, and 38.2% to 67.6% for a meander belt. The processes that lead to a decrease in preservation include intra-meanderbend erosion (due to downstream translation or bar rotation), and increasing meanderbend sinuosity and eventual cutoff (neck and chute), as well as inter-meander-bend erosion due to avulsion and subsequent migration of the meandering channel. The results of this study document a decrease in preservation over time that follows a natural logarithmic function of decay; we have termed this the "survivability" curve. The results presented here document a systematic, monotonic decrease in preservation over time, which is consistent regardless of the spatial or temporal scale and agrees with probabilities of preservation at long time scales proposed by previous workers. A comparison between data sets allows for an estimation of the time span represented by meander-belt deposits in the deep time record.
- Subject
- fluvial deposits; stratigraphic record; channel migration; erosion
- Identifier
- http://hdl.handle.net/1959.13/1387185
- Identifier
- uon:32550
- Identifier
- ISSN:0016-7606
- Rights
- © 2017 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license.
- Language
- eng
- Full Text
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