Geology of Chryse Planitia

Abstract

On July 20, 1976, Viking 1 made the first successful landing on Mars in Chryse Planitia, a plains covered basin in the northern hemisphere. Viking orbiter pictures reveal more surface detail of the area and show the basin to be more complex than was seen on Mariner 9 images. The plains consist of areas with smooth and relatively uniform surfaces with prominent lunarlike mare ridges, mesas and plateaus, surfaces that appear to be ‘etched,’ fields of knobs, low shields that may be volcanic, and vast areas that have been subjected to channel‐forming processes. At least two sets of channels, originating from distant sources, terminate in Chryse Planitia. The four major units of the basin are basal hilly and cratered terrain, plateau material which can be divided into upper and lower units, lower smooth plains, and upper smooth plains. There is no evidence for the origin of the basin. Deposition of the plateau‐forming material to the east followed the period of bombardment, and since that time the history of the basin includes eruptions of flood lavas, channel formation, and deposition with at least two channel‐forming events. The later history of the basin includes possible local volcanic events, etching, and aeolian activity.

Episodes of fluvial and volcanic activity in Mangala Valles, Mars

“…Most plateaued knobs are between 150 and 300 m in height, while the more rounded knobs tend to be less than 150 m in height. The stepped/terraced topographic profile of these landforms suggests that these features more likely represent streamlined erosion of layered bedrock rather than depositional bars (Baker and Kochel, 1979;Milton, 1974;Greeley et al, 1977). .…”

Sedimentary history and mass flow structures of Chryse and Acidalia Planitiae, Mars

“…Investigations have focused on (1) channel history [e.g., Milton, 1974 Thus far, geologic maps of Chryse and Acidalia Planitiae (CAP) have been either detailed but limited in coverage [Greeley et al, 1977;Crumpler, 1995] …”

Martian paleolakes and waterways: Exobiological implications

“…This possible connection is not indicated by regional topography (U.S. Geological Survey, 1989), but it can be inferred to exist along the corridor of low-lying plains of the Arcadia Formation (see Scott and Tanaka, 1986;Tanaka and Scott, 1987). Previous work in the Chryse basin region (Greeley et al, 1977) mentioned albedo patterns that could represent fluvial deposits. Large-scale mapping (J.…”

“…Although Carr's estimate is larger than those obtained by other, less direct methods, it may be conservative; the aquifers providing discharge to cut the outflow channel may not have been completely drained in the process, and more than one flood episode probably occurred. Greeley et al (1977) recognized the probability of recurrent flooding elsewhere in the Chryse region. More recent studies Scott and Dohm, 1990) showed that multiple flood episodes probably occurred within Kasei Valles, one of the largest channel systems of the Chryse basin, as well as within large outflow channels in other areas .…”