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Formation of sinuous ridges by inversion of river-channel belts in Utah, USA, with implications for Mars

Hayden, Alistair T. and Lamb, Michael P. and Fischer, Woodward W. and Ewing, Ryan C. and McElroy, Brandon J. and Williams, Rebecca M. E. (2019) Formation of sinuous ridges by inversion of river-channel belts in Utah, USA, with implications for Mars. Icarus, 332 . pp. 92-110. ISSN 0019-1035. https://resolver.caltech.edu/CaltechAUTHORS:20190423-094241490

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Abstract

Sinuous ridges are important landforms on the surface of Mars that show promise for quantifying ancient martian surface hydrology. Morphological similarity of these ridges to river channels in planform led to a hypothesis that ridges are topographically inverted river channels, or “inverted channels”, formed due to an erosion-resistant channel-filling material that preserved a snapshot of the channel geometry in inverted relief due to differential erosion. An alternative deposit-inversion hypothesis proposes that ridges represent exhumed river-channel belts, with geometries that reflect the lateral migration and vertical aggradation of rivers over significant geologic time, rather than the original channel geometry. To investigate these hypotheses we studied sinuous ridges within the Cretaceous Cedar Mountain Formation near Green River, Utah, USA. Ridges in Utah extend for hundreds of meters, are up to 120 m wide, and stand up to 39 m above the surrounding plain. Ridges are capped by sandstone bodies 3–10 m thick that contain dune- and bar-scale inclined stratification, which we interpret as eroded remnants of channel belts that record the migration and aggradation of single-thread, sand-bedded rivers, rather than channel fills that can preserve the original channel geometry. Caprocks overlie mudstones and thinner sandstone beds that are interpreted as floodplain deposits, and in cases additional channel-belt sandstones are present lower in the ridge stratigraphy. Apparent networks from branching ridges typically represent discrete sandstone bodies that cross at different stratigraphic levels rather than a coeval river network. Ridge-forming sandstone bodies also have been narrowed during exhumation by cliff retreat and bisected by fluvial erosion. Using a large compilation of channel-belt geometries on Earth and our measurements of ridges in Utah, we propose that caprock thickness is the most reliable indicator of paleo-channel geometry, and can be used to reconstruct river depth and discharge. In contrast, channel lateral migration and caprock erosion during exhumation make ridge breadth an uncertain proxy for channel width. An example in Aeolis Dorsa, Mars, illustrates that river discharge estimates based solely on caprock width may differ significantly from estimates based on caprock thickness. Overall, our study suggests that sinuous ridges are not inverted channel fills, but rather reflect exhumation of a thick stratigraphic package of stacked channel belts and overbank deposits formed from depositional rivers over significant geologic time.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.icarus.2019.04.019DOIArticle
ORCID:
AuthorORCID
Lamb, Michael P.0000-0002-5701-0504
Fischer, Woodward W.0000-0002-8836-3054
Ewing, Ryan C.0000-0001-6337-610X
Additional Information:© 2019 Published by Elsevier. Received 31 August 2018, Revised 15 February 2019, Accepted 18 April 2019, Available online 22 April 2019. Field data collection was aided by the 2015 field classes of Texas A&M, University of Wyoming, and Caltech. This work was supported by NASA (grant NNX16AQ81G to Caltech and NNX13AG83G to RMEW), Caltech's Terrestrial Hazard Observation and Reporting program, and the Donors of the American Chemical Society Petroleum Research Fund (53544DNI8 to RCE). ATH acknowledges graduate fellowship support from NASA (80NSSC17K0492) and NSF (1144469). We also thank two anonymous reviewers for their helpful comments. Declaration of interests: None.
Funders:
Funding AgencyGrant Number
NASANNX16AQ81G
NASANNX13AG83G
Terrestrial Hazard Observation and Reporting CenterUNSPECIFIED
American Chemical Society Petroleum Research Fund53544DNI8
NASA Graduate Student Research Fellowship80NSSC17K0492
NSF Graduate Research FellowshipDGE-1144469
Subject Keywords:Mars, surface; Mars; Earth; Geological processes
Record Number:CaltechAUTHORS:20190423-094241490
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190423-094241490
Official Citation:Alistair T. Hayden, Michael P. Lamb, Woodward W. Fischer, Ryan C. Ewing, Brandon J. McElroy, Rebecca M.E. Williams, Formation of sinuous ridges by inversion of river-channel belts in Utah, USA, with implications for Mars, Icarus, Volume 332, 2019, Pages 92-110, ISSN 0019-1035, https://doi.org/10.1016/j.icarus.2019.04.019. (http://www.sciencedirect.com/science/article/pii/S0019103518305803)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94886
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:23 Apr 2019 16:55
Last Modified:03 Oct 2019 21:08

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