Rivers and Lakes in Western Arabia Terra: The Fluvial Catchment of the
ExoMars 2022 rover landing site
Abstract
Oxia Planum, the landing site for the ExoMars rover mission, is a
shallow basin on the southern margin of Chryse Planitia that hosts
remnants of sediment fans associated with the ancient channel system
Coogoon Vallis. This indicates runoff from a catchment in Arabia Terra
has transported material into the landing site. To explore this fluvial
system we created a model catchment for Oxia Planum and, using 6 m/pixel
ConTeXt camera (CTX) orbital remote sensing image data, we digitised the
fluvial and lacustrine landforms in Western Arabia Terra in and around
this catchment. We find: (1) The catchment has a minimum area of
~2.1×105 km2 and has
been episodically deformed by tectonic activity; (2) There were at least
two phases of fluvial activity. The first created a mature landscape
associated with Coogoon Vallis, which may have deposited alluvial or
deltaic deposits in the Oxia Basin. After a substantial hiatus, a second
phase of activity incised u-section channels into the pre-existing
landscape and channel systems; and (3) Evidence for numerous possible
paleolake deposits within the catchment. These are not well connected to
the fluvial system and were probably sustained by ground water activity
contemporaneous with both phases of fluvial activity. This groundwater
might have modified the geochemistry of Oxia Planum. Oxia Planum
probably experienced an alluvial or distal deltaic/lacustrine
depositional environment during the mid Noachian, which was later
overprinted by a younger phase of fluvial activity.