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Published October 2022 | metadata_only
Journal Article

Paleogeographic Reconstructions of an Ocean Margin on Mars Based on Deltaic Sedimentology at Aeolis Dorsa


The evidence for an ancient ocean in Mars' northern hemispheric basin during the Noachian/Hesperian is contentious. Much of the work is based on the modern topography by assuming that erosion has not significantly reshaped the Martian surface over the last 3.5 billion years, despite evidence to the contrary. Here, we provide new evidence for a northern ocean or large sea based on stratigraphic analysis of sedimentary basin fill exposed at Aeolis Dorsa. We mapped over 6,500 km of fluvial ridges, grouped them into 20 systems, and present evidence that they are the eroded remnants of river deltas or submarine-channel belts, together defining the stratigraphy of an ancient ocean margin. We used Context Camera stereo-pair elevation models to measure the stratigraphic positions of each system and used branching directions to determine paleoflow directions. By grouping landforms based on stratigraphic position and paleoflow directions, we reconstructed the paleogeography at Aeolis Dorsa over 5 timesteps; all cases differ from the modern topography. We tracked the initial regression and later transgression of a shoreline during at least 900 m of sea-level rise, a scale consistent with a northern ocean on a warm and wet early Mars.

Additional Information

The authors thank Editor Bradley Thomson and Associate Editor Joel Davis for the handling of our manuscript, and two reviewers whose comments helped improve the text. The authors also acknowledge Alistair Hayden and Jay Dickson for CTX DEM processing, and Jay Dickson for assistance in Caltech's Bruce Murray Laboratory for Planetary Visualization (http://murray-lab.caltech.edu/) where all mapping and analyses were performed. John Grotzinger, Chris Paola, Paul Myrow, and Woody Fischer are acknowledged for helpful discussions. MPL acknowledges funding from NASA grant NNX16AQ81G1960. Data Availability Statement Shapefiles and Python scripts upon which all analysis was based can be found on the CaltechDATA repository (Cardenas, 2022). CTX DEMs can be found on Zenodo (Cardenas et al., 2022), and were processed from CTX images (Malin, 2007). The CTX seamless global mosaic can be accessed through Caltech's Murray Lab for Planetary Visualization: http://murray-lab.caltech.edu/CTX/index.html. The Northern Gulf of Mexico deepwater bathymetry grid from 3D seismic produced by the US Department of the Interior's Bureau of Ocean Energy Management (Bureau of Ocean Energy Management, 2017) can be downloaded here: https://www.boem.gov/oil-gas-energy/mapping-and-data/map-gallery/northern-gom-deepwater-bathymetry-grid-3d-seismic

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August 22, 2023
September 11, 2023