Colombera, L orcid.org/0000-0001-9116-1800 and Mountney, NP orcid.org/0000-0002-8356-9889 (2019) The lithofacies organization of fluvial channel deposits: a meta-analysis of modern rivers. Sedimentary Geology, 383. pp. 16-40. ISSN 0037-0738
Abstract
Environmental interpretations of subsurface fluvial successions are commonly based on facies observations from core and are often attempted by generalist geologists by reference to classic facies models. However, for fluvial channel deposits, the value of observations on lithofacies proportions for interpretations of depositional environment has yet to be assessed quantitatively. Here, a test is presented that is based on a comparative study of facies data from 77 reaches of 46 modern rivers. The analysis is undertaken on datasets from published case studies stored in a sedimentological database, with consideration of causes for observational bias, and with particular attention paid to sandy lithofacies. The observed variability in the proportion of facies assemblages in the channel deposits of sandy river systems is quantified for classes of environments categorized according to channel pattern (braided, low sinuosity, meandering), climatic setting (arid to perhumid), and discharge regime (ephemeral to perennial). By capturing the variability in facies organization within fluvial systems of certain types, these outputs serve as facies models that provide a measure of uncertainty to sedimentological interpretations. Concurrently, the statistical analysis presented enables a test of the significance of relationships between the relative proportions of channel lithofacies and parameters that either represent controlling factors (e.g., water-discharge characteristics) or covariates (e.g., channel pattern). For classes of river systems grouped by channel pattern, climate, and discharge regime, emerging features of facies organization can be identified. Statistically, it is observed that relationships exist (i) between channel pattern and the frequency of the preserved expression of bedforms, and (ii) between controls on river hydrology (climate, discharge regime and seasonal variability) and the record of upper and lower flow-regime conditions. Thus, the results corroborate existing qualitative facies models in some respects. However, observations of the relative dominance of facies in channel deposits demonstrate limited value for interpretations or predictions in subsurface or outcrop studies, as variability within each type of depositional system is significant. Corehole data of fluvial channel deposits may be commonly overinterpreted.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 Elsevier B.V. This is an author produced version of a paper published in Sedimentary Geology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | fluvial facies models; channel pattern; braided; meandering; low sinuosity; discharge variability |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute for Applied Geosciences (IAG) (Leeds) |
Funding Information: | Funder Grant number NERC NE/N017218/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 05 Feb 2019 11:20 |
Last Modified: | 01 Feb 2020 01:38 |
Status: | Published |
Publisher: | Elsevier BV |
Identification Number: | 10.1016/j.sedgeo.2019.01.011 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:141823 |
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