Episodic flood inundations of the northern plains of Mars

Abstract

Throughout the recorded history of Mars, liquid water has distinctly shaped its landscape, including the prominent circum-Chryse and the northwestern slope valleys outflow channel systems, and the extremely flat northern plains topography at the distal reaches of these outflow channel systems. Paleotopographic reconstructions of the Tharsis magmatic complex reveal the existence of an Europe-sized Noachian drainage basin and subsequent aquifer system in eastern Tharsis. This basin is proposed to have sourced outburst floodwaters that sculpted the outflow channels, and ponded to form various hypothesized oceans, seas, and lakes episodically through time. These floodwaters decreased in volume with time due to inadequate groundwater recharge of the Tharsis aquifer system. Martian topography, as observed from the Mars Orbiter Laser Altimeter, corresponds well to these ancient flood inundations, including the approximated shorelines that have been proposed for the northern plains. Stratigraphy, geomorphology, and topography record at least one great Noachian-Early Hesperian northern plains ocean, a Late Hesperian sea inset within the margin of the high water marks of the previous ocean, and a number of widely distributed minor lakes that may represent a reduced Late Hesperian sea, or ponded waters in the deepest reaches of the northern plains related to minor Tharsis-and Elysium-induced Amazonian flooding.

New evidence for a magmatic influence on the origin of Valles Marineris, Mars

“…The use of a "standard" wet diabase for the Martian crust is consistent with extensive evidence for water-related geologic activity in early Mars (e.g., Fairén et al, 2003). For strain rates, we use values of 10 − 16 s − 1 and 10 − 19 s − 1 , a range usually considered for Mars (e.g., McGovern et al, 2004;Ruiz et al, 2008).…”

Reduced albedo on early Mars does not solve the climate paradox under a faint young Sun

“…Geologic evidence of flowing and ponding liquid water on the surface of ancient Mars appears abundantly across most of the Martian landscape (Baker et al 1991;Parker et al 1993;Head et al 1998;Clifford & Parker 2001;Fairén et al 2003;Malin & Edgett 2003;Squyres et al 2004;Irwin et al 2005;Pain et al 2007;Di Achille & Hynek 2010), indicating that liquid water has been present in variable amounts and for long periods of time on and/or near the surface at different moments of Mars' history. Early Mars appears to have been "wet".…”

Thermal isostasy and deformation of possible paleoshorelines on Mars

“…Though it is not our intention to discuss in detail the many factors that may have contributed to the modification of an equipotential surface here, we do highlight some of the possibilities, which may include modification by wind, water, cratering, tectonic, and volcanic processes (e.g., Clifford and Parker, 2001;Faire´n et al, 2003), rebound of the lithosphere due to dissipation of a water body (Leverington and Ghent, 2004; for a review of isostatic and flexural effects related to changes in sea level, see Watts, 2001), flexure and/or (non-thermal) isostasy due to surface loading or erosion, or subsurface magmatic intrusions. In fact, both endogenic-driven geologic activity (probably implying vertical movements) and exogenic activity clearly postdate the possible paleoshorelines in Arabia Terra and in Tharsis and Elysium magmatic complexes (e.g., Scott and Tanaka, 1986;Greeley and Guest, 1987;Head et al, 1999;Anderson et al, 2001).…”

“…Several investigators have proposed the possible existence of large bodies of water in the northern plains of Mars that range from oceans (Parker et al, 1989(Parker et al, , 1993Clifford and Parker, 2001) to lakes (Scott et al, 1995), and several paleoshorelines have been proposed. While Edgett (1999, 2001) indicate that there is not sufficient evidence to support the shoreline hypothesis through analysis of high-resolution MOC imagery targeted in specific putative shoreline localities, other investigators present arguments that dispute these findings Clifford and Parker, 2001;Faire´n et al, 2003). Similarly, an origin for the putative Deuteronilus shoreline related to coastal processes is considered unclear (Carr and Head, 2003) or likely (Webb and McGill, 2003), based on geologic and elevation relations along this feature.…”

“…Elevation in this possible paleoshoreline is roughly similar to that of the Arabia shoreline in northeast Arabia, Utopia (not taking into account the Isidis basin), Elysium, and Amazonis regions. Thus, a paleoshoreline through these regions and the Meridiani shoreline Faire´n et al, 2003) is a better candidate to represent a paleoequipotential surface than the Arabia shoreline; their elevation range, although not specifically examined, would be mostly about 2 km (from À1 to À3 km; as a reference see the elevation profile along the Arabia shoreline in Fig. 5 in Carr and Head, 2003).…”