Plains and channels in the Lunae Planum—Chryse Planitia Region of Mars

Abstract

The Lunae Planum-Chryse Planitia region provides the opportunity to study a sequence of channeling events and to determine their temporal and genetic relationships to plains units in the northern hemisphere of Mars. Two sets of small channels and four major channel systems can be divided into four periods of channeling by superposition and contact relationships to the plains. All of the channels are considered to have formed by water erosion. The first two channeling events occurred early in the history of this area and formed small, narrow channels within the old rugged terrain. These channel events were separated by deposition of a mantle unit. The small channels probably formed by runoff of surface water or by a sapping process. These channels preceded the emplacement of vast volcanic plains in both Lunae Planum and Chryse Planitia. Channels postdating the plains are Vedra, Maumee, Bahram, and Maja valles; the first three of these deposited a sedimentary unit on the western slope of Chryse Planitia that was eroded by Maja Vallis. These large-scale channels were probably formed predominantly by catastrophic floods and may represent two periods of water release from Juventae Chasma. The origin of Bahram Vallis remains uncertain. Geomorphology Regional SettingLunae Planum is an elevated plains in the northern hemisphere of Mars (Figure 1), characterized by relatively low albedo and a ridged texture. Immediately east ofLunae Planum but separated from it by a zone of rugged terrain is Chryse Planitia, a large asymmetric basin of smooth plains. The total relief from the center of the plateau to the lowest part of the basin, one of the lowest points on Mars, is about 8 km. A series of channels including small unnamed channels and Vedra, Maumee, Bahram, and Maja valles extend from Lunae Planum into the basin. To the north, Chryse Planitia grades into Acidalia Planitia, part of the extensive northern plains. A scarp separates Lunae Planum from the Tharsis volcanic plains to the west. To the south the area ends at a series of troughs and canyons which are the western end of the equatorial Vallis Marineris system. One channel originating in this area extends along the base of the western scarp and then turns eastward, forming Kasei Vallis, the northern boundary of Lunae Planum. Smooth Plains Lunae Planum was described by Milton [1974] as an area of predominantly smooth plains with scattered craters and lunadike wrinkle ridges. The smooth plains in Chryse Planitia were distinguished from these by their featureless appearance and relatively smaller crater population [Milton, 1974; Wilhelms, 1976]. Higher-resolution Viking images have revealed a diverse surface in Chryse Planitia with wrinkle ridges, areas modified by an erosional process, channeling, and fields of knobs [Greeley'et al., 1977]. On the plateau the increased image resolution reveals a mottled surface with numerous distinct wrinkle ridges, high-albedo areas with a 7994

Rootless cones on Mars: a consequence of lava-ground ice interaction

“…Carr et al 1977;Gault & Greeley 1978;Mouginis-Mark 1987), and are characterized by a lobate ejecta blanket; and (iii) pingoes, which are ice-cored sediment mounds formed in periglacial lake or permafrost environments (Theilig & Greeley 1979;Lucchitta 1981;Rossbacher & Judson 1981;Cabrol et al 2000). In many cases, the morphological and stratigraphic characteristics of candidate martian rootless cones rule out a non-volcanic origin (although in others, image resolution precludes a confident interpretation).…”

Related Magma–Ice Interactions: Possible Origins of Chasmata, Chaos, and Surface Materials in Xanthe, Margaritifer, and Meridiani Terrae, Mars

“…Stratigraphic relations and geomorphic features indicate that the Kasei and Maja Valles systems have had at least two episodes of erosion (Neukum and Hiller 1981, Chapman and Scott 1989, Chapman et al 1991, Tanaka and Chapman 1992, Baker 1982, Theilig and Greeley 1979). Some of the major channel surfaces have similar crater densities and may have been active simulta- neously, whereas others have distinctly separate ages (Rotto and Tanaka 1995).…”

Possible pingos and a periglacial landscape in northwest Utopia Planitia

“…in the planetary science literature have been brief (De Hon, 1997;Greeley and Guest, 1987;Seibert and Kargel, 2001;Lucchitta, 1981Lucchitta, , 1993Parker and Banerdt, 1999;Rice et al, 2002;Theilig and Greeley, 1979) and/or based upon Viking imagery (Cabrol et al, 1997(Cabrol et al, , 2000Grin and Cabrol, 1998).…”

“…On Mars, landscapes that include small, elongate to circular mounds hypothesised to be pingos, as well as other possible periglacial features have been identified in three areas: (1) the vast northern plains (Kargel and Costard, 1993;Parker and Banerdt, 1999;Seibert and Kargel, 2001) encompassing Acadilia (Lucchitta, 1981), Chryse (Theilig and Greeley, 1979), Elysium (De Hon, 1997;Rice et al, 2002), and Utopia Planitiae (Tanaka et al, 2000;Seibert and Kargel, 2001; Thomson and Head, 2001); (2) Vastitas Borealis (Greeley and Guest, 1987); and (3) the Gusev crater (Cabrol et al, 1997(Cabrol et al, , 2000Grin and Cabrol, 1998). Water is thought to have played an important role in the landscape evolution of each area.…”