Deltaic deposits at Aeolis Dorsa: Sedimentary evidence for a standing body of water on the northern plains of Mars

Roman A. DiBiase, Ajay B. Limaye, Joel S. Scheingross, Woodward W. Fischer, Michael P. Lamb

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

A fundamental long-standing question regarding Mars history is whether the flat and low-lying northern plains ever hosted an ocean. The best opportunity to solve this problem is provided by stratigraphic observations of sedimentary deposits onlapping the crustal dichotomy. Here, we use high-resolution imagery and topography to analyze a branching network of inverted channel and channel lobe deposits in the Aeolis Dorsa region, just north of the dichotomy boundary. Observations of stacked, cross-cutting channel bodies and stratal geometries indicate that these landforms represent exhumed distributary channel deposits. Observations of depositional trunk feeder channel bodies, a lack of evidence for past topographic confinement, channel avulsions at similar elevations, and the presence of a strong break in dip slope between topset and foreset beds suggest that this distributary system was most likely a delta, rather than an alluvial fan or submarine fan. Sediment transport calculations using both measured and derived channel geometries indicate a minimum delta deposition time on the order of 400 years. The location of this delta within a thick and widespread clastic wedge abutting the crustal dichotomy boundary, unconfined by any observable craters, suggests a standing body of water potentially 105 km 2 in extent or greater and is spatially consistent with hypotheses for a northern ocean. Key Points Stratigraphic analysis reveals paleoflow direction of branching channel networksBackwater scaling relationships enable flow reconstructions of deltaic depositsDeltaic deposits at Aeolis Dorsa support the presence of a past unconfined sea

Original languageEnglish (US)
Pages (from-to)1285-1302
Number of pages18
JournalJournal of Geophysical Research E: Planets
Volume118
Issue number6
DOIs
StatePublished - 2013

Keywords

  • Mars
  • delta
  • inverted topography
  • ocean
  • river

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