Topographic influences on development of Martian valley networks

Abstract

[1] Some morphometric differences between terrestrial and Martian valley networks may reflect the precursor topography on Mars, particularly impact basins or tectonic slopes. To evaluate these possible influences, we mapped highland watersheds in nine study areas that sample a range of geographic and topographic settings. We collected data including latitude, longitude, watershed length, divide and terminal elevations, watershed relief and slope, slope orientation, and qualitative descriptors including whether a drainage basin was open or closed. The longest valley networks and most overflowed basins occur on preexisting intercrater slopes of 0.1-1°, particularly on north facing slopes associated with the crustal dichotomy. The control of watershed length by earlier Noachian topographic features, which the relict networks did not significantly modify, suggests that the Early to Middle Noachian geomorphic environment was nominally much drier than the later Noachian to Hesperian transition. The distribution of fluvial valleys and likely orographic effects created by the crustal dichotomy suggest that evaporation from the northern lowlands was an important source of atmospheric humidity over short time scales. Much of the highland plateau consists of smaller enclosed watersheds, which (along with cooler temperatures) detained surface water at high elevations, lengthening or impeding the global water cycle. Ponding and evaporation may have partly offset a continentality effect of the highland landmass. Prolonged modification of the intercrater geomorphic surface prior to incision of valley networks included substantial weathering, reduction of relief, and gravity-driven sediment transport, indicating a long-term role for surface water in a transport-limited, arid to hyperarid Noachian paleoclimate.

Paleohydrology of Eberswalde crater, Mars

“…Degradation of impact craters throughout the Noachian Period and into the Hesperian Period required a more effective geomorphic regime than is found currently on Mars (Craddock and Maxwell, 1993;Grant and Schultz, 1993a;Craddock et al, 1997;Forsberg-Taylor et al, 2004;Golombek et al, 2006). The multibasin landscape with numerous impact craters and undissected areas between tributaries is, however, inconsistent with high long-term rates of erosion under sustained humid conditions, relative to Earth (e.g., Pieri, 1980;Carr and Malin, 2000;Irwin et al, 2011).…”

Glaciation in the Late Noachian Icy Highlands: Ice accumulation, distribution, flow rates, basal melting, and top-down melting rates and patterns

“…The existence of liquid water that flowed across the surface (Carr, 1995); Irwin et al, 2005;Fassett and Head, 2008a; Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/pss 2010) as well as open-and closed-basin lakes (Fassett and Head, 2008b) has led many to suggest that early Mars was "warm and wet" with rainfall (pluvial) activity (Masursky et al, 1977;Craddock and Maxwell, 1990;Craddock and Maxwell, 1993;Craddock et al, 1997;Clifford and Parker, 2001;Hynek and Phillips, 2001;Craddock and Howard, 2002;Pondrelli et al, 2008;Achille and Hynek, 2010). Furthermore, many studies suggest prolonged periods of rainfall in amounts at least comparable to that occurring in Earth's arid or semiarid regions (Barnhart et al, 2009;Hoke et al, 2011;Howard, 2007;Irwin et al, 2011;Matsubara et al, 2013). Associated lakes, deltas, and alluvial fans show complex histories of fluctuating water and sediment discharges (Malin and Edgett, 2003;Moore and Howard, 2005;Di Achille et al, 2006;Head, 2005, 2008; Di Achille and Hynek, 2010;Ponderelli et al, 2010;Grant et al, 2011;Buhler et al, 2011Buhler et al, , 2014Hoke et al, 2014), and these have often been interpreted to imply extended periods of precipitation and runoff (Moore et al, 2003;Jerolmack et al, 2004;Matsubara et al, 2011).…”

Global drainage patterns and the origins of topographic relief on Earth, Mars, and Titan

“…This topography may have been generated through basin-scale impacts (4) or through other unknown processes. Geomorphic mapping suggests that valley networks were strongly influenced by ancient topographic gradients, but that younger NoachianHesperian cratering did modify and disrupt some river paths (2,23).…”