Inverted fluvial features in the Aeolis/Zephyria Plana region, Mars: Formation mechanism and initial paleodischarge estimates

Abstract

[1] A subset of the sinuous ridges (SRs) in the Aeolis/Zephyria Plana (AZP) region of Mars has been previously hypothesized to be inverted fluvial features, although the precise induration and erosion mechanisms were not specified. Morphological observations and thermal inertia data presented here support this hypothesis. A variety of mechanisms can cause inversion, and identification of the specific events that lead to fluvial SR formation can provide insights into the sedimentological, geochemical, and climatic processes of the region. Reconnaissance of two terrestrial lava-capped ridges suggests some criteria that may be used to identify inverted fluvial features formed by lava infill on Mars, but these criteria are not satisfied by the majority of the AZP fluvial SRs. Armoring also appears inconsistent with terrestrial analogs. Layering and surface textures of fluvial SRs indicate that the most likely induration mechanism was geochemical cementation of fluvial sediments, and that the primary erosional mechanism that exposed the fluvial SRs was aeolian abrasion. This analysis of formation mechanism provides a foundation for estimating paleodischarge using an empirical form-discharge approach, to which we have applied scaling, for Martian gravity. For those fluvial SRs meeting a set of criteria for accurate paleodischarge estimates, paleodischarge values generally range between 10 1 and 10 3 m 3 s −1. The largest of these initial estimates are comparable to paleodischarge estimates for some late-stage Noachian fluvial channels on Mars, and provide a constraint on the atmospheric conditions at this equatorial location during the late Hesperian to early Amazonian time frame.

Sedimentology and climatic environment of alluvial fans in the martian Saheki crater and a comparison with terrestrial fans in the Atacama Desert

“…7), as suggested by Moore and Howard (2005). Similar inverted features interpreted as scroll bars occur on the Eberswalde crater delta (Malin and Edgett, 2003;Moore et al, 2003) and sinuous channels in the Aeolis-Zephyria region (Burr et al, 2009(Burr et al, , 2010. It is likely that flow did not occupy the entire width of these broad expanses at any given time.…”

“…The aeolian erosion that inverts the distributaries serves to expose the channels, but may also narrow them as a result of lateral backwasting of the channel edges by mass wasting triggered by aeolian erosion of weaker surrounding layers. Burr et al (2010) conclude that many inverted meandering channels in the Aeolis Dorsa/Zephyria Plana region have been significantly narrowed because of an observed meander wavelength to preserved ridge width that significantly exceeds the typical terrestrial value of about 10-14 (Knighton, 1998, p. 215). In some environments, however, wavelength/width ratios can reach 20-25, as along the low gradient, mud-bank Quinn River in Nevada (Matsubara et al, 2012).…”

“…Limited HiRISE coverage over other fans in the vicinity of Saheki ( Fig. 1) and the lack of additional well-preserved flat-topped ridges in other fan systems prevents a thorough assessment of channel widths elsewhere, though channel widths appear to be qualitatively similar (Burr et al, 2010;Grant and Wilson, 2012).…”

Plateaus and sinuous ridges as the fingerprints of lava flow inflation in the Eastern Tharsis Plains of Mars

“…Sinuous ridges found elsewhere across the surface of Mars are interpreted as inverted fluvial channels (Malin and Edgett, 2003;Mangold et al, 2004;Moore and Howard, 2005;Pain et al, 2007;Burr et al, 2009Burr et al, , 2010Williams et al, 2009;Anderson and Bell, 2010;Zimbelman and Griffin, 2010;Le Deit et al, 2010;Weitz et al, 2010;Newsom et al, 2010;Thomson et al, 2011;Ansan et al, 2011;Lefort et al, 2012), eskers (Baker, 2001;Head and Pratt, 2001;Bleacher et al, 2003;Ghatan and Head, 2004;Banks et al, 2009;Williams et al, 2013), or eroded remnants of subsurface dikes (Head et al, 2006). The development of inverted fluvial channels and eskers involves flowing water, and all three of these proposed processes require significant erosion and regional deflation.…”

Fluvial Landforms and the Post-Noachian Environment on Mars

“…Some investigations, however, suggest valleys required at least regionally extensive precipitation, either producing direct runoff or melting of accumulated snow and ice Mangold et al, 2004Mangold et al, , 2008Burr et al, 2010;]. At present, evidence for Amazonian-Hesperian paleolakes that are contemporaneous with fluvial valley formation is limited, but previous studies include examples from Tempe Terra along the dichotomy boundary (35.6°N 305.3°E) , the region near Ares Vallis (0-17°N, 330-350°E) , Eberswalde crater [e.g., as summarized in and Gorgonum basin (37°S, 189°E) .…”